The Effect of Dielectric Constants on Noble Metal/Semiconductor SERS Enhancement: FDTD Simulation and Experiment Validation of Ag/Ge and Ag/Si Substrates

PubMed Central

Wang, Tao; Zhang, Zhaoshun; Liao, Fan; Cai, Qian; Li, Yanqing; Lee, Shuit-Tong; Shao, Mingwang

2014-01-01

The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 109) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 107 and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones. PMID:24514430

InGaP solar cell on Ge-on-Si virtual substrate for novel solar power conversion

NASA Astrophysics Data System (ADS)

Kim, T. W.; Albert, B. R.; Kimerling, L. C.; Michel, J.

2018-02-01

InGaP single-junction solar cells are grown on lattice-matched Ge-on-Si virtual substrates using metal-organic chemical vapor deposition. Optoelectronic simulation results indicate that the optimal collection length for InGaP single-junction solar cells with a carrier lifetime range of 2-5 ns is wider than approximately 1 μm. Electron beam-induced current measurements reveal that the threading dislocation density (TDD) of InGaP solar cells fabricated on Ge and Ge-on-Si substrates is in the range of 104-3 × 107 cm-2. We demonstrate that the open circuit voltage (Voc) of InGaP solar cells is not significantly influenced by TDDs less than 2 × 106 cm-2. Fabricated InGaP solar cells grown on a Ge-on-Si virtual substrate and a Ge substrate exhibit Voc in the range of 0.96 to 1.43 V under an equivalent illumination in the range of ˜0.5 Sun. The estimated efficiency of the InGaP solar cell fabricated on the Ge-on-Si virtual substrate (Ge substrate) at room temperature for the limited incident spectrum spanning the photon energy range of 1.9-2.4 eV varies from 16.6% to 34.3%.

The effect of dielectric constants on noble metal/semiconductor SERS enhancement: FDTD simulation and experiment validation of Ag/Ge and Ag/Si substrates.

PubMed

Wang, Tao; Zhang, Zhaoshun; Liao, Fan; Cai, Qian; Li, Yanqing; Lee, Shuit-Tong; Shao, Mingwang

2014-02-11

The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 10(9)) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 10(7) and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones.

Growth of BaSi2 film on Ge(100) by vacuum evaporation and its photoresponse properties

NASA Astrophysics Data System (ADS)

Trinh, Cham Thi; Nakagawa, Yoshihiko; Hara, Kosuke O.; Kurokawa, Yasuyoshi; Takabe, Ryota; Suemasu, Takashi; Usami, Noritaka

2017-05-01

We have successfully grown a polycrystalline orthorhombic BaSi2 film on a Ge(100) substrate by an evaporation method. Deposition of an amorphous Si (a-Si) film on the Ge substrate prior to BaSi2 evaporation plays a critical role in obtaining a high-quality BaSi2 film. By controlling substrate temperature and the thickness of the a-Si film, a crack-free and single-phase polycrystalline orthorhombic BaSi2 film with a long carrier lifetime of 1.5 µs was obtained on Ge substrates. The photoresponse property of the ITO/BaSi2/Ge/Al structure was clearly observed, and photoresponsivity was found to increase with increasing substrate temperature during deposition of a-Si. Furthermore, the BaSi2 film grown on Ge showed a higher photoresponsivity than that grown on Si, indicating the potential application of evaporated BaSi2 on Ge to thin-film solar cells.

Atomic structure of self-organizing iridium induced nanowires on Ge(001)

NASA Astrophysics Data System (ADS)

Kabanov, N. S.; Heimbuch, R.; Zandvliet, H. J. W.; Saletsky, A. M.; Klavsyuk, A. L.

2017-05-01

The atomic structure of self-organizing iridium (Ir) induced nanowires on Ge(001) is studied by density functional theory (DFT) calculations and variable-temperature scanning tunneling microscopy. The Ir induced nanowires are aligned in a direction perpendicular to the Ge(001) substrate dimer rows, have a width of two atoms and are completely kink-less. Density functional theory calculations show that the Ir atoms prefer to dive into the Ge(001) substrate and push up the neighboring Ge substrate atoms. The nanowires are composed of Ge atoms and not Ir atoms as previously assumed. The regions in the vicinity of the nanowires are very dynamic, even at temperatures as low as 77 K. Time-resolved scanning tunneling microscopy measurements reveal that this dynamics is caused by buckled Ge substrate dimers that flip back and forth between their two buckled configurations.

High performance Ω-gated Ge nanowire MOSFET with quasi-metallic source/drain contacts.

PubMed

Burchhart, T; Zeiner, C; Hyun, Y J; Lugstein, A; Hochleitner, G; Bertagnolli, E

2010-10-29

Ge nanowires (NWs) about 2 µm long and 35 nm in diameter are grown heteroepitaxially on Si(111) substrates in a hot wall low-pressure chemical vapor deposition (LP-CVD) system using Au as a catalyst and GeH(4) as precursor. Individual NWs are contacted to Cu pads via e-beam lithography, thermal evaporation and lift-off techniques. Self-aligned and atomically sharp quasi-metallic copper-germanide source/drain contacts are achieved by a thermal activated phase formation process. The Cu(3)Ge segments emerge from the Cu contact pads through axial diffusion of Cu which was controlled in situ by SEM, thus the active channel length of the MOSFET is adjusted without any restrictions from a lithographic process. Finally the conductivity of the channel is enhanced by Ga(+) implantation leading to a high performance Ω-gated Ge-NW MOSFET with saturation currents of a few microamperes.

Characterization of High Ge Content SiGe Heterostructures and Graded Alloy Layers Using Spectroscopic Ellipsometry

NASA Technical Reports Server (NTRS)

Heyd, A. R.; Alterovitz, S. A.; Croke, E. T.

1995-01-01

Si(x)Ge(1-x)heterostructures on Si substrates have been widely studied due to the maturity of Si technology. However, work on Si(x)Ge)1-x) heterostructures on Ge substrates has not received much attention. A Si(x)Ge(1-x) layer on a Si substrate is under compressive strain while Si(x)Ge(1-x) on Ge is under tensile strain; thus the critical points will behave differently. In order to accurately characterize high Ge content Si(x)Ge(1-x) layers the energy shift algorithm used to calculate alloy compositions, has been modified. These results have been used along with variable angle spectroscopic ellipsometry (VASE) measurements to characterize Si(x)Ge(1-x)/Ge superlattices grown on Ge substrates. The results agree closely with high resolution x-ray diffraction measurements made on the same samples. The modified energy shift algorithm also allows the VASE analysis to be upgraded in order to characterize linearly graded layers. In this work VASE has been used to characterize graded Si(x)Ge(1-x) layers in terms of the total thickness, and the start and end alloy composition. Results are presented for a 1 micrometer Si(x)Ge(1-x) layer linearly graded in the range 0.5 less than or equal to x less than or equal to 1.0.

Controllable growth of GeSi nanostructures by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Ma, Yingjie; Zhou, Tong; Zhong, Zhenyang; Jiang, Zuimin

2018-06-01

We present an overview on the recent progress achieved on the controllable growth of diverse GeSi alloy nanostructures by molecular beam epitaxy. Prevailing theories for controlled growth of Ge nanostructures on patterned as well as inclined Si surfaces are outlined firstly, followed by reviews on the preferential growth of Ge nanoislands on patterned Si substrates, Ge nanowires and high density nanoislands grown on inclined Si surfaces, and the readily tunable Ge nanostructures on Si nanopillars. Ge nanostructures with controlled geometries, spatial distributions and densities, including two-dimensional ordered nanoislands, three-dimensional ordered quantum dot crystals, ordered nanorings, coupled quantum dot molecules, ordered nanowires and nanopillar alloys, are discussed in detail. A single Ge quantum dot-photonic crystal microcavity coupled optical emission device demonstration fabricated by using the preferentially grown Ge nanoisland technique is also introduced. Finally, we summarize the current technology status with a look at the future development trends and application challenges for controllable growth of Ge nanostructures. Project supports by the Natural Science Foundation of China (Nos. 61605232, 61674039) and the Open Research Project of State Key Laboratory of Surface Physics from Fudan University (Nos. KF2016_15s, KF2017_05).

Nucleation Of Ge 3D-islands On Pit-patterned Si Substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novikov, P. L.; Smagina, J. V.; Vlasov, D. Yu.

2011-12-23

Joint experimental and theoretical study of Ge nanoislands growth on pit-patterned Si substrate is carried out. Si substrates that have been templated by means of electron beam lithography and reactive ion etching have been used to grow Ge by molecular-beam epitaxy. Atomic-force-microscopy studies show that at Si(100) substrate temperature 550 deg. C, Ge nanoislands are formed at the pits' edges, rather than between the pits. The effect is interpreted in terms of energy barrier, that is formed near the edge of a pit and prevents Ge transport inside the pit. By molecular dynamics calculations the value of the energy barriermore » 0.9 eV was obtained.« less

Germanium-Assisted Direct Growth of Graphene on Arbitrary Dielectric Substrates for Heating Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ziwen; Xue, Zhongying; Zhang, Miao

Direct growth of graphene on dielectric substrates is a prerequsite for the development of graphene-based electronic and optoelectronic devices. However, the current graphene synthesis directly on dielectric substrates always involves metal contamination problem, and the direct production of graphene patterns still remains unattainable and challenging. We propose herein a semiconducting Ge-assisted chemical vapor deposition approach to directly grow monolayer graphene on arbitrary dielectric substrates. By pre-patterning of catalytic Ge layer, the graphene with desired pattern can be achieved with extreme ease. Due to the catalysis of Ge, monolayer graphene is able to form on Ge covered dielectric substrates including SiOmore » 2/Si, quartz glass and sapphire substrates. Optimization of the process parameters leads to the complete sublimation of catalytic Ge layer during or immediately after monolayer graphene formation, thus resulting in direct deposition of large-area continuous graphene on dielectric substrates. The large-area, highly conductive graphene synthesized on transparent dielectric substrate using the proposed approach has exhibited wide applications, e.g., in defogger and in thermochromic displays, with both devices possessing excellent performances.« less

Germanium-Assisted Direct Growth of Graphene on Arbitrary Dielectric Substrates for Heating Devices

DOE PAGES

Wang, Ziwen; Xue, Zhongying; Zhang, Miao; ...

2017-05-31

Direct growth of graphene on dielectric substrates is a prerequsite for the development of graphene-based electronic and optoelectronic devices. However, the current graphene synthesis directly on dielectric substrates always involves metal contamination problem, and the direct production of graphene patterns still remains unattainable and challenging. We propose herein a semiconducting Ge-assisted chemical vapor deposition approach to directly grow monolayer graphene on arbitrary dielectric substrates. By pre-patterning of catalytic Ge layer, the graphene with desired pattern can be achieved with extreme ease. Due to the catalysis of Ge, monolayer graphene is able to form on Ge covered dielectric substrates including SiOmore » 2/Si, quartz glass and sapphire substrates. Optimization of the process parameters leads to the complete sublimation of catalytic Ge layer during or immediately after monolayer graphene formation, thus resulting in direct deposition of large-area continuous graphene on dielectric substrates. The large-area, highly conductive graphene synthesized on transparent dielectric substrate using the proposed approach has exhibited wide applications, e.g., in defogger and in thermochromic displays, with both devices possessing excellent performances.« less

Selective growth of Ge nanowires by low-temperature thermal evaporation.

PubMed

Sutter, Eli; Ozturk, Birol; Sutter, Peter

2008-10-29

High-quality single-crystalline Ge nanowires with electrical properties comparable to those of bulk Ge have been synthesized by vapor-liquid-solid growth using Au growth seeds on SiO(2)/Si(100) substrates and evaporation from solid Ge powder in a low-temperature process at crucible temperatures down to 700 °C. High nanowire growth rates at these low source temperatures have been identified as being due to sublimation of GeO from substantial amounts of GeO(2) on the powder. The Ge nanowire synthesis from GeO is highly selective at our substrate temperatures (420-500 °C), i.e., occurs only on Au vapor-liquid-solid growth seeds. For growth of nanowires of 10-20 µm length on Au particles, an upper bound of 0.5 nm Ge deposition was determined in areas of bare SiO(2)/Si substrate without Au nanoparticles.

Epitaxial Ge Solar Cells Directly Grown on Si (001) by MOCVD Using Isobutylgermane

NASA Astrophysics Data System (ADS)

Kim, Youngjo; Kim, Kangho; Lee, Jaejin; Kim, Chang Zoo; Kang, Ho Kwan; Park, Won-Kyu

2018-03-01

Epitaxial Ge layers have been grown on Si (001) substrates by metalorganic chemical vapor deposition (MOCVD) using an isobutylgermane (IBuGe) metalorganic source. Low and high temperature two-step growth and post annealing techniques are employed to overcome the lattice mismatch problem between Ge and Si. It is demonstrated that high quality Ge epitaxial layers can be grown on Si (001) by using IBuGe with surface RMS roughness of 2 nm and an estimated threading dislocation density of 4.9 × 107 cm -2. Furthermore, single-junction Ge solar cells have been directly grown on Si substrates with an in situ MOCVD growth. The epitaxial Ge p- n junction structures are investigated with transmission electron microscopy and electrochemical C- V measurements. As a result, a power conversion efficiency of 1.69% was achieved for the Ge solar cell directly grown on Si substrate under AM1.5G condition.

Texture analysis of CoGe2 alloy films grown heteroepitaxially on GaAs(100) using partially ionized beam deposition

NASA Astrophysics Data System (ADS)

Mello, K. E.; Murarka, S. P.; Lu, T.-M.; Lee, S. L.

1997-06-01

Reflection x-ray pole figure analysis techniques were used to study the heteroepitaxial relationships of the cobalt germanide CoGe2 to GaAs(100). The alloy films were grown using the partially ionized beam deposition technique, in which low energy Ge+ ions are employed to alter the heteroepitaxial orientation of the CoGe2 deposits. The CoGe2[001](100)∥GaAs[100](001) orientation, which has the smallest lattice mismatch, was found to occur for depositions performed at a substrate temperature around 280 °C and with ˜1200 eV Ge+ ions. Lowering the substrate temperature or reducing the Ge+ ion energy leads to CoGe2(100) orientation domination with CoGe2[100](010)∥GaAs[100](001) and CoGe2[100](001)∥GaAs[100](001). Substrate temperature alone was seen to produce only the CoGe2(100) orientation. For CoGe2(001) films, additional energy was required from Ge+ ions in the evaporant stream.

X-ray characterization of Ge dots epitaxially grown on nanostructured Si islands on silicon-on-insulator substrates.

PubMed

Zaumseil, Peter; Kozlowski, Grzegorz; Yamamoto, Yuji; Schubert, Markus Andreas; Schroeder, Thomas

2013-08-01

On the way to integrate lattice mismatched semiconductors on Si(001), the Ge/Si heterosystem was used as a case study for the concept of compliant substrate effects that offer the vision to be able to integrate defect-free alternative semiconductor structures on Si. Ge nanoclusters were selectively grown by chemical vapour deposition on Si nano-islands on silicon-on-insulator (SOI) substrates. The strain states of Ge clusters and Si islands were measured by grazing-incidence diffraction using a laboratory-based X-ray diffraction technique. A tensile strain of up to 0.5% was detected in the Si islands after direct Ge deposition. Using a thin (∼10 nm) SiGe buffer layer between Si and Ge the tensile strain increases to 1.8%. Transmission electron microscopy studies confirm the absence of a regular grid of misfit dislocations in such structures. This clear experimental evidence for the compliance of Si nano-islands on SOI substrates opens a new integration concept that is not only limited to Ge but also extendable to semiconductors like III-V and II-VI materials.

Interface Engineering for Atomic Layer Deposited Alumina Gate Dielectric on SiGe Substrates.

PubMed

Zhang, Liangliang; Guo, Yuzheng; Hassan, Vinayak Vishwanath; Tang, Kechao; Foad, Majeed A; Woicik, Joseph C; Pianetta, Piero; Robertson, John; McIntyre, Paul C

2016-07-27

Optimization of the interface between high-k dielectrics and SiGe substrates is a challenging topic due to the complexity arising from the coexistence of Si and Ge interfacial oxides. Defective high-k/SiGe interfaces limit future applications of SiGe as a channel material for electronic devices. In this paper, we identify the surface layer structure of as-received SiGe and Al2O3/SiGe structures based on soft and hard X-ray photoelectron spectroscopy. As-received SiGe substrates have native SiOx/GeOx surface layers, where the GeOx-rich layer is beneath a SiOx-rich surface. Silicon oxide regrows on the SiGe surface during Al2O3 atomic layer deposition, and both SiOx and GeOx regrow during forming gas anneal in the presence of a Pt gate metal. The resulting mixed SiOx-GeOx interface layer causes large interface trap densities (Dit) due to distorted Ge-O bonds across the interface. In contrast, we observe that oxygen-scavenging Al top gates decompose the underlying SiOx/GeOx, in a selective fashion, leaving an ultrathin SiOx interfacial layer that exhibits dramatically reduced Dit.

Thin SiGe virtual substrates for Ge heterostructures integration on silicon

NASA Astrophysics Data System (ADS)

Cecchi, S.; Gatti, E.; Chrastina, D.; Frigerio, J.; Müller Gubler, E.; Paul, D. J.; Guzzi, M.; Isella, G.

2014-03-01

The possibility to reduce the thickness of the SiGe virtual substrate, required for the integration of Ge heterostructures on Si, without heavily affecting the crystal quality is becoming fundamental in several applications. In this work, we present 1 μm thick Si1-xGex buffers (with x > 0.7) having different designs which could be suitable for applications requiring a thin virtual substrate. The rationale is to reduce the lattice mismatch at the interface with the Si substrate by introducing composition steps and/or partial grading. The relatively low growth temperature (475 °C) makes this approach appealing for complementary metal-oxide-semiconductor integration. For all the investigated designs, a reduction of the threading dislocation density compared to constant composition Si1-xGex layers was observed. The best buffer in terms of defects reduction was used as a virtual substrate for the deposition of a Ge/SiGe multiple quantum well structure. Room temperature optical absorption and photoluminescence analysis performed on nominally identical quantum wells grown on both a thick graded virtual substrate and the selected thin buffer demonstrates a comparable optical quality, confirming the effectiveness of the proposed approach.

Controlled Spalling in (100)-Oriented Germanium by Electroplating

NASA Astrophysics Data System (ADS)

Crouse, Dustin Ray

This work investigates controlled spalling as a method to exfoliate thin films of various thickness from rigid, crystalline germanium (Ge) substrates and to enable substrate reuse for III-V single junction photovoltaic devices. Technological limitations impeding wide-spread adoption of flexible electronics and high-material-cost photovoltaic devices have motivated significant interest in a method to remove devices from their substrates. DC magnetron sputtering has been previously utilized to remove semiconductor devices of various thicknesses from Ge substrates, but this method is expensive and time-consuming. Controlled spalling via high-speed electrodeposition is a fast, inexpensive exfoliation method that utilizes a tensile-stressed metal layer deposited on a (100)-oriented Ge substrate and an external force to mechanically propagate a crack parallel to the surface at a desired depth in the substrate material. Suo and Hutchinson's quantitative models describe critical combinations of film thickness and strain mismatch between a film and substrate at which a stressed bilayer system spontaneously spalls; however, fine control over a wide steady-state spall depth range has been limited by the ability to experimentally tailor strain mismatch caused by residual stress within deposited stressor layers. This work investigates the effect of tuning electroplating current density and electrolyte chemistry on the residual stress in a nickel stressor film and their impact on the achievable spall depth range. Steady-state spall depth is found to increase with increasing stressor layer thickness and decrease with increasing residual stress. By tailoring residual stress through adjusting plating conditions and the electrolyte's phosphorous concentration, wide control over spall depth within Ge substrates from sub-micron to 76microm-thicknesses were achieved. To assess the viability of utilizing controlled spalling for substrate reuse, this dissertation demonstrates the first III-V solar cells (GaInAsP, Eg 1.7 eV) grown directly on a spalled-Ge substrate without any additional surface preparation. Widespread adoption of high-efficiency III-V solar cells has been limited by expensive deposition processes and high material cost of substrates. Substrate reuse offers a promising route towards enabling III-V devices to become cost-competitive for one-sun terrestrial applications. In this study, the quality of spalled Ge surfaces is characterized to assess lattice matching capability between the device layer materials and the substrate. GaAs films grown on spalled Ge substrates by hydride vapor phase epitaxy were single-crystal in nature. III-V solar cells grown on spalled and pristine Ge substrates show nearly equivalent efficiency of 8%, despite the roughness of the spalled-Ge substrate. Principles of fractography were used to deduce that surface roughness originated from non-uniform crack propagation and mixed-mode loading during the spalling process.

Low Temperature Rhombohedral Single Crystal SiGe Epitaxy on c-plane Sapphire

NASA Technical Reports Server (NTRS)

Duzik, Adam J.; Choi, Sang H.

2016-01-01

Current best practice in epitaxial growth of rhombohedral SiGe onto (0001) sapphire (Al2O3) substrate surfaces requires extreme conditions to grow a single crystal SiGe film. Previous models described the sapphire surface reconstruction as the overriding factor in rhombohedral epitaxy, requiring a high temperature Al-terminated surface for high quality films. Temperatures in the 850-1100 C range were thought to be necessary to get SiGe to form coherent atomic matching between the (111) SiGe plane and the (0001) sapphire surface. Such fabrication conditions are difficult and uneconomical, hindering widespread application. This work proposes an alternative model that considers the bulk sapphire structure and determines how the SiGe film nucleates and grows. Accounting for thermal expansion effects, calculations using this new model show that both pure Ge and SiGe can form single crystal films in the 450-550 C temperature range. Experimental results confirm these predictions, where x-ray diffraction and atomic force microscopy show the films fabricated at low temperature rival the high temperature films in crystallographic and surface quality. Finally, an explanation is provided for why films of comparable high quality can be produced in either temperature range.

Aluminum induced crystallization of amorphous Ge thin films on insulating substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Ch. Kishan, E-mail: kisn@igcar.gov.in; Tah, T.; Sunitha, D. T.

2016-05-23

Aluminium (metal) induced crystallization of amorphous Ge in bilayer and multilayer Ge/Al thin films deposited on quartz substrate at temperature well below the crystallization temperature of bulk Ge is reported. The crystallization of poly-Ge proceeds via formations of dendritic crystalline Ge grains in the Al matrix. The observed phases were characterized by Raman spectroscopy and X-ray diffraction. The microstructure of Al thin film layer was found to have a profound influence on such crystallization process and formation of dendritic grains.

Auger electron diffraction study of the initial stage of Ge heteroepitaxy on Si(001)

NASA Astrophysics Data System (ADS)

Sasaki, M.; Abukawa, T.; Yeom, H. W.; Yamada, M.; Suzuki, S.; Sato, S.; Kono, S.

1994-12-01

The initial stage of pure and surfactant (Sb)-assisted Ge growth on a Si(001) surface has been studied by Auger electron diffraction (AED) and X-ray photoelectron diffraction (XPD). A single-domain Si(001)2 × 1 substrate was used to avoid the ambiguity arising from the usual double-domain substrate. For the pure Ge growth, 1 monolayer of Ge was deposited onto the room temperature substrate followed by annealing at 350°C-600°C, which appeared to have (1 × 2) periodicity by LEED. Ge LMM AED patterns were measured to find that a substantial amount of Ge atoms diffuse to the bulk Si positions up to the fourth layer at least. For the Sb-assisted Ge growth, a Sb(1 × 2)/Si(001) surface was first prepared and Sb 3d XPD patterns were measured to find that Sb forms dimers on the substrate. 1 ML of Ge was deposited onto the Sb(1 × 2)/Si(001) surface and then the surface was annealed at 600°C. Ge LMM AED and Sb 3d XPD patterns measured for this surface showed that surfactant Sb atoms are indeed present on the first layer forming dimers and that Ge atoms are present mainly on the second layer with a substantial amount of Ge diffused into the third and fourth layers.

Dramatically enhanced self-assembly of GeSi quantum dots with superior photoluminescence induced by the substrate misorientation

NASA Astrophysics Data System (ADS)

Zhou, Tong; Zhong, Zhenyang

2014-02-01

A dramatically enhanced self-assembly of GeSi quantum dots (QDs) is disclosed on slightly miscut Si (001) substrates, leading to extremely dense QDs and even a growth mode transition. The inherent mechanism is addressed in combination of the thermodynamics and the growth kinetics both affected by steps on the vicinal surface. Moreover, temperature-dependent photoluminescence spectra from dense GeSi QDs on the miscut substrate demonstrate a rather strong peak persistent up to 300 K, which is attributed to the well confinement of excitons in the dense GeSi QDs due to the absence of the wetting layer on the miscut substrate.

Fabrication of tensile-strained single-crystalline GeSn on transparent substrate by nucleation-controlled liquid-phase crystallization

NASA Astrophysics Data System (ADS)

Oka, Hiroshi; Amamoto, Takashi; Koyama, Masahiro; Imai, Yasuhiko; Kimura, Shigeru; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2017-01-01

We developed a method of forming single-crystalline germanium-tin (GeSn) alloy on transparent substrates that is based on liquid-phase crystallization. By controlling and designing nucleation during the melting growth process, a highly tensile-strained single-crystalline GeSn layer was grown on a quartz substrate without using any crystal-seeds or catalysts. The peak field-effect hole mobility of 423 cm2/V s was obtained for a top-gate single-crystalline GeSn MOSFET on a quartz substrate with a Sn content of 2.6%, indicating excellent crystal quality and mobility enhancement due to Sn incorporation and tensile strain.

High Quality GaAs Growth by MBE on Si Using GeSi Buffers and Prospects for Space Photovoltaics

NASA Technical Reports Server (NTRS)

Carlin, J. A.; Ringel, S. A.; Fitzgerald, E. A.; Bulsara, M.

2005-01-01

III-V solar cells on Si substrates are of interest for space photovoltaics since this would combine high performance space cells with a strong, lightweight and inexpensive substrate. However, the primary obstacles blocking III-V/Si cells from achieving high performance to date have been fundamental materials incompatabilities, namely the 4% lattice mismatch between GaAs and Si, and the large mismatch in thermal expansion coefficient. In this paper, we report on the molecular beam epitaxial (MBE) growth and properties of GaAs layers and single junction GaAs cells on Si wafers which utilize compositionally graded GeSi Intermediate buffers grown by ultra-high vacuum chemical vapor deposition (UHVCVD) to mitigate the large lattice mismatch between GaAs and Si. Ga As cell structures were found to incorporate a threading dislocation density of 0.9-1.5 x 10 (exp 6) per square centimeter, identical to the underlying relaxed Ge cap of the graded buffer, via a combination of transmission electron microscopy, electron beam induced current, and etch pit density measurements. AlGaAs/GaAs double heterostructures wre grown on the GeSi/Si substrates for time-resolved photoluminescence measurements, which revealed a bulk GaAs minority carrier lifetime in excess of 10 ns, the highest lifetime ever reported for GaAs on Si. A series of growth were performed to ass3ss the impact of a GaAs buffer to a thickness of only 0.1 micrometer. Secondary ion mass spectroscopy studies revealed that there is negligible cross diffusion of Ga, As and Ge at he III-V/Ge interface, identical to our earlier findings for GaAs grown on Ge wafers using MBE. This indicates that there is no need for a buffer to "bury" regions of high autodopjing,a nd that either pn or np configuration cells are easily accomodated by these substrates. Preliminary diodes and single junction Al Ga As heteroface cells were grown and fabricated on the Ge/GeSi/Si substrates for the first time. Diodes fabricated on GaAs, Ge and Ge/GeSi/Si substrate show nearly identical I-V characteristics in both forward and reverse bias regions. External quantum efficiencies of AlGaAs/GaAs cell structures grown on Ge/GeSi/Si and Ge substrates demonstrated nearly identical photoresponse, which indicates that high lifetimes, diffusion lengths and efficient minority carrier collection is maintained after complete cell processing.

Towards rhombohedral SiGe epitaxy on 150mm c-plane sapphire substrates

NASA Astrophysics Data System (ADS)

Duzik, Adam J.; Park, Yeonjoon; Choi, Sang H.

2015-04-01

Previous work demonstrated for the first time the ability to epitaxially grow uniform single crystal diamond cubic SiGe (111) films on trigonal sapphire (0001) substrates. While SiGe (111) forms two possible crystallographic twins on sapphire (0001), films consisting primarily of one twin were produced on up to 99.95% of the total wafer area. This permits new bandgap engineering possibilities and improved group IV based devices that can exploit the higher carrier mobility in Ge compared to Si. Models are proposed on the epitaxy of such dissimilar crystal structures based on the energetic favorability of crystallographic twins and surface reconstructions. This new method permits Ge (111) on sapphire (0001) epitaxy, rendering Ge an economically feasible replacement for Si in some applications, including higher efficiency Si/Ge/Si quantum well solar cells. Epitaxial SiGe films on sapphire showed a 280% increase in electron mobility and a 500% increase in hole mobility over single crystal Si. Moreover, Ge possesses a wider bandgap for solar spectrum conversion than Si, while the transparent sapphire substrate permits an inverted device structure, increasing the total efficiency to an estimated 30-40%, much higher than traditional Si solar cells. Hall Effect mobility measurements of the Ge layer in the Si/Ge/Si quantum well structure were performed to demonstrate the advantage in carrier mobility over a pure Si solar cell. Another application comes in the use of microelectromechanical devices technology, where high-resistivity Si is currently used as a substrate. Sapphire is a more resistive substrate and offers better performance via lower parasitic capacitance and higher film carrier mobility over the current Si-based technology.

X-ray characterization of Ge dots epitaxially grown on nanostructured Si islands on silicon-on-insulator substrates

PubMed Central

Zaumseil, Peter; Kozlowski, Grzegorz; Yamamoto, Yuji; Schubert, Markus Andreas; Schroeder, Thomas

2013-01-01

On the way to integrate lattice mismatched semiconductors on Si(001), the Ge/Si heterosystem was used as a case study for the concept of compliant substrate effects that offer the vision to be able to integrate defect-free alternative semiconductor structures on Si. Ge nanoclusters were selectively grown by chemical vapour deposition on Si nano-islands on silicon-on-insulator (SOI) substrates. The strain states of Ge clusters and Si islands were measured by grazing-incidence diffraction using a laboratory-based X-ray diffraction technique. A tensile strain of up to 0.5% was detected in the Si islands after direct Ge deposition. Using a thin (∼10 nm) SiGe buffer layer between Si and Ge the tensile strain increases to 1.8%. Transmission electron microscopy studies confirm the absence of a regular grid of misfit dislocations in such structures. This clear experimental evidence for the compliance of Si nano-islands on SOI substrates opens a new integration concept that is not only limited to Ge but also extendable to semiconductors like III–V and II–VI materials. PMID:24046490

Ge-rich islands grown on patterned Si substrates by low-energy plasma-enhanced chemical vapour deposition.

PubMed

Bollani, M; Chrastina, D; Fedorov, A; Sordan, R; Picco, A; Bonera, E

2010-11-26

Si(1-x)Ge(x) islands grown on Si patterned substrates have received considerable attention during the last decade for potential applications in microelectronics and optoelectronics. In this work we propose a new methodology to grow Ge-rich islands using a chemical vapour deposition technique. Electron-beam lithography is used to pre-pattern Si substrates, creating material traps. Epitaxial deposition of thin Ge films by low-energy plasma-enhanced chemical vapour deposition then leads to the formation of Ge-rich Si(1-x)Ge(x) islands (x > 0.8) with a homogeneous size distribution, precisely positioned with respect to the substrate pattern. The island morphology was characterized by atomic force microscopy, and the Ge content and strain in the islands was studied by μRaman spectroscopy. This characterization indicates a uniform distribution of islands with high Ge content and low strain: this suggests that the relatively high growth rate (0.1 nm s(-1)) and low temperature (650 °C) used is able to limit Si intermixing, while maintaining a long enough adatom diffusion length to prevent nucleation of islands outside pits. This offers the novel possibility of using these Ge-rich islands to induce strain in a Si cap.

Method of using a germanium layer transfer to Si for photovoltaic applications and heterostructure made thereby

DOEpatents

Atwater, Jr., Harry A.; Zahler, James M.

2006-11-28

Ge/Si and other nonsilicon film heterostructures are formed by hydrogen-induced exfoliation of the Ge film which is wafer bonded to a cheaper substrate, such as Si. A thin, single-crystal layer of Ge is transferred to Si substrate. The bond at the interface of the Ge/Si heterostructures is covalent to ensure good thermal contact, mechanical strength, and to enable the formation of an ohmic contact between the Si substrate and Ge layers. To accomplish this type of bond, hydrophobic wafer bonding is used, because as the invention demonstrates the hydrogen-surface-terminating species that facilitate van der Waals bonding evolves at temperatures above 600.degree. C. into covalent bonding in hydrophobically bound Ge/Si layer transferred systems.

One-step Ge/Si epitaxial growth.

PubMed

Wu, Hung-Chi; Lin, Bi-Hsuan; Chen, Huang-Chin; Chen, Po-Chin; Sheu, Hwo-Shuenn; Lin, I-Nan; Chiu, Hsin-Tien; Lee, Chi-Young

2011-07-01

Fabricating a low-cost virtual germanium (Ge) template by epitaxial growth of Ge films on silicon wafer with a Ge(x)Si(1-x) (0 < x < 1) graded buffer layer was demonstrated through a facile chemical vapor deposition method in one step by decomposing a hazardousless GeO(2) powder under hydrogen atmosphere without ultra-high vacuum condition and then depositing in a low-temperature region. X-ray diffraction analysis shows that the Ge film with an epitaxial relationship is along the in-plane direction of Si. The successful growth of epitaxial Ge films on Si substrate demonstrates the feasibility of integrating various functional devices on the Ge/Si substrates.

Very thin, high Ge content Si 0.3Ge 0.7 relaxed buffer grown by MBE on SOI(0 0 1) substrate

NASA Astrophysics Data System (ADS)

Myronov, M.; Shiraki, Y.

2007-04-01

Growth procedure and excellent properties of very thin 240 nm thick, 95% relaxed, high Ge content Si 0.3Ge 0.7 buffer grown on SOI(0 0 1) substrate are demonstrated. All epilayers of the newly developed Si 0.3Ge 0.7/SOI(0 0 1) variable-temperature virtual substrate were grown in a single process by solid-source molecular beam epitaxy. Surface analysis of grown samples revealed smooth, cross-hatch free surface with low root mean square surface roughness of 0.9 nm and low threading dislocations density of 5×10 4 cm -2.

Towards III-V solar cells on Si: Improvement in the crystalline quality of Ge-on-Si virtual substrates through low porosity porous silicon buffer layer and annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calabrese, Gabriele; Baricordi, Stefano; Bernardoni, Paolo

2014-09-26

A comparison between the crystalline quality of Ge grown on bulk Si and on a low porosity porous Si (pSi) buffer layer using low energy plasma enhanced chemical vapor deposition is reported. Omega/2Theta coupled scans around the Ge and Si (004) diffraction peaks show a reduction of the Ge full-width at half maximum (FWHM) of 22.4% in presence of the pSi buffer layer, indicating it is effective in improving the epilayer crystalline quality. At the same time atomic force microscopy analysis shows an increase in root means square roughness for Ge grown on pSi from 38.5 nm to 48.0 nm,more » as a consequence of the larger surface roughness of pSi compared to bulk Si. The effect of 20 minutes vacuum annealing at 580°C is also investigated. The annealing leads to a FWHM reduction of 23% for Ge grown on Si and of 36.5% for Ge on pSi, resulting in a FWHM of 101 arcsec in the latter case. At the same time, the RMS roughness is reduced of 8.8% and of 46.5% for Ge grown on bulk Si and on pSi, respectively. The biggest improvement in the crystalline quality of Ge grown on pSi with respect to Ge grown on bulk Si observed after annealing is a consequence of the simultaneous reorganization of the Ge epilayer and the buffer layer driven by energy minimization. A low porosity buffer layer can thus be used for the growth of low defect density Ge on Si virtual substrates for the successive integration of III-V multijunction solar cells on Si. The suggested approach is simple and fast –thus allowing for high throughput-, moreover is cost effective and fully compatible with subsequent wafer processing. Finally it does not introduce new chemicals in the solar cell fabrication process and can be scaled to large area silicon wafers.« less

Controlled formation of GeSi nanostructures on pillar-patterned Si substrate

NASA Astrophysics Data System (ADS)

Zhou, Tong; Zeng, Ceng; Fan, Yongliang; Jiang, Zuimin; Xia, Jinsong; Zhong, Zhenyang; Fudan University Team; Huazhong University of Science; Technology Collaboration

2015-03-01

GeSi quantum nanostructures (QNs) have potential applications in optoelectronic devices due to their unique properties and compatibility with the sophisticated Si technology. However, the disadvantages of poor quantum efficiency of the GeSi QNs on flat Si (001) substrates hinder their optoelectronic applications. Today, numerous growth strategies have been proposed to control the formation of GeSi QNs in hope of improving the optoelectronic performances. One of the ways is to fabricate GeSi QNs on patterned substrates, where the GeSi QNs can be greatly manipulated in aspects of size, shape, composition, orientation and arrangement. Here, self-assembled GeSi QNs on periodic Si (001) sub-micro pillars (SPMs) are systematically studied. By controlling the growth conditions and the diameters of the SPMs, different GeSi QNs, including circularly arranged quantum dots (QDs), quantum rings (QRs), and quantum dot molecules (QDMs), are realized at the top edge of SMPs. Meanwhile, fourfold symmetric GeSi QDMs can be also obtained at the base edges of the SPMs. The promising features of self-assembled GeSi QNs are explained in terms of the surface chemical potential, which disclose the critical effect of surface morphology on the diffusion and the aggregation of Ge adatoms.

Thermal annealing studies of GeTe-Sb2Te3 alloys with multiple interfaces

NASA Astrophysics Data System (ADS)

Bragaglia, Valeria; Mio, Antonio M.; Calarco, Raffaella

2017-08-01

A high degree of vacancy ordering is obtained by annealing amorphous GeTe-Sb2Te3 (GST) alloys deposited on a crystalline substrate, which acts as a template for the crystallization. Under annealing the material evolves from amorphous to disordered rocksalt, to ordered rocksalt with vacancies arranged into (111) oriented layers, and finally converts into the stable trigonal phase. The role of the interface in respect to the formation of an ordered crystalline phase is studied by comparing the transformation stages of crystalline GST with and without a capping layer. The capping layer offers another crystallization interface, which harms the overall crystalline quality.

Straight single-crystalline germanium nanowires and their patterns grown on sol gel prepared gold/silica substrates

NASA Astrophysics Data System (ADS)

Pan, Zheng Wei; Dai, Sheng; Lowndes, Douglas H.

2005-04-01

Straight single-crystalline Ge nanowires with a uniform diameter distribution of 50-80 nm and lengths up to tens of micrometers were grown in a high yield on sol-gel prepared gold/silica substrates by using Ge powder as the Ge source. Detailed electron microscopy analyses show that the nanowires grow through a vapor-liquid-solid growth mechanism with gold nanoparticles located at the nanowire tips. By using transmission electron microscope grids as the shadow mask, the sol-gel technique can be readily adapted to prepare patterned film-like gold/silica substrates, so that regular micropatterns of Ge nanowires were obtained, which could facilitate the integration of Ge nanowires for characterization and devices.

High efficiency epitaxial GaAs/GaAs and GaAs/Ge solar cell technology using OM/CVD

NASA Technical Reports Server (NTRS)

Wang, K. L.; Yeh, Y. C. M.; Stirn, R. J.; Swerdling, S.

1980-01-01

A technology for fabricating high efficiency, thin film GaAs solar cells on substrates appropriate for space and/or terrestrial applications was developed. The approach adopted utilizes organometallic chemical vapor deposition (OM-CVD) to form a GaAs layer epitaxially on a suitably prepared Ge epi-interlayer deposited on a substrate, especially a light weight silicon substrate which can lead to a 300 watt per kilogram array technology for space. The proposed cell structure is described. The GaAs epilayer growth on single crystal GaAs and Ge wafer substrates were investigated.

Vertical epitaxial wire-on-wire growth of Ge/Si on Si(100) substrate.

PubMed

Shimizu, Tomohiro; Zhang, Zhang; Shingubara, Shoso; Senz, Stephan; Gösele, Ulrich

2009-04-01

Vertically aligned epitaxial Ge/Si heterostructure nanowire arrays on Si(100) substrates were prepared by a two-step chemical vapor deposition method in anodic aluminum oxide templates. n-Butylgermane vapor was employed as new safer precursor for Ge nanowire growth instead of germane. First a Si nanowire was grown by the vapor liquid solid growth mechanism using Au as catalyst and silane. The second step was the growth of Ge nanowires on top of the Si nanowires. The method presented will allow preparing epitaxially grown vertical heterostructure nanowires consisting of multiple materials on an arbitrary substrate avoiding undesired lateral growth.

SiGe derivatization by spontaneous reduction of aryl diazonium salts

NASA Astrophysics Data System (ADS)

Girard, A.; Geneste, F.; Coulon, N.; Cardinaud, C.; Mohammed-Brahim, T.

2013-10-01

Germanium semiconductors have interesting properties for FET-based biosensor applications since they possess high surface roughness allowing the immobilization of a high amount of receptors on a small surface area. Since SiGe combined low cost of Si and intrinsic properties of Ge with high mobility carriers, we focused the study on this particularly interesting material. The comparison of the efficiency of a functionalization process involving the spontaneous reduction of diazonium salts is studied on Si(1 0 0), SiGe and Ge semiconductors. XPS analysis of the functionalized surfaces reveals the presence of a covalent grafted layer on all the substrates that was confirmed by AFM. Interestingly, the modified Ge derivatives have still higher surface roughness after derivatization. To support the estimated thickness by XPS, a step measurement of the organic layers is done by AFM or by profilometer technique after a O2 plasma etching of the functionalized layer. This original method is well-adapted to measure the thickness of thin organic films on rough substrates such as germanium. The analyses show a higher chemical grafting on SiGe substrates compared with Si and Ge semiconductors.

The effect of Ge precursor on the heteroepitaxy of Ge1-x Sn x epilayers on a Si (001) substrate

NASA Astrophysics Data System (ADS)

Jahandar, Pedram; Weisshaupt, David; Colston, Gerard; Allred, Phil; Schulze, Jorg; Myronov, Maksym

2018-03-01

The heteroepitaxial growth of Ge1-x Sn x on a Si (001) substrate, via a relaxed Ge buffer, has been studied using two commonly available commercial Ge precursors, Germane (GeH4) and Digermane (Ge2H6), by means of chemical vapour deposition at reduced pressures (RP-CVD). Both precursors demonstrate growth of strained and relaxed Ge1-x Sn x epilayers, however Sn incorporation is significantly higher when using the more reactive Ge2H6 precursor. As Ge2H6 is significantly more expensive, difficult to handle or store than GeH4, developing high Sn content epilayers using the latter precursor is of great interest. This study demonstrates the key differences between the two precursors and offers routes to process optimisation which will enable high Sn content alloys at relatively low cost.

Homogeneity of Ge-rich nanostructures as characterized by chemical etching and transmission electron microscopy.

PubMed

Bollani, Monica; Chrastina, Daniel; Montuori, Valeria; Terziotti, Daniela; Bonera, Emiliano; Vanacore, Giovanni M; Tagliaferri, Alberto; Sordan, Roman; Spinella, Corrado; Nicotra, Giuseppe

2012-02-03

The extension of SiGe technology towards new electronic and optoelectronic applications on the Si platform requires that Ge-rich nanostructures be obtained in a well-controlled manner. Ge deposition on Si substrates usually creates SiGe nanostructures with relatively low and inhomogeneous Ge content. We have realized SiGe nanostructures with a very high (up to 90%) Ge content. Using substrate patterning, a regular array of nanostructures is obtained. We report that electron microscopy reveals an abrupt change in Ge content of about 20% between the filled pit and the island, which has not been observed in other Ge island systems. Dislocations are mainly found within the filled pit and only rarely in the island. Selective chemical etching and electron energy-loss spectroscopy reveal that the island itself is homogeneous. These Ge-rich islands are possible candidates for electronic applications requiring locally induced stress, and optoelectronic applications which exploit the Ge-like band structure of Ge-rich SiGe.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Taehoon; Jung, Yong Chan; Seong, Sejong

The metal gate electrodes of Ni, W, and Pt have been investigated for their scavenging effect: a reduction of the GeO{sub x} interfacial layer (IL) between HfO{sub 2} dielectric and Ge substrate in metal/HfO{sub 2}/GeO{sub x}/Ge capacitors. All the capacitors were fabricated using the same process except for the material used in the metal electrodes. Capacitance-voltage measurements, scanning transmission electron microscopy, and electron energy loss spectroscopy were conducted to confirm the scavenging of GeO{sub x} IL. Interestingly, these metals are observed to remotely scavenge the interfacial layer, reducing its thickness in the order of Ni, W, and then Pt. Themore » capacitance equivalent thickness of these capacitors with Ni, W, and Pt electrodes are evaluated to be 2.7 nm, 3.0 nm, and 3.5 nm, and each final remnant physical thickness of GeO{sub x} IL layer is 1.1 nm 1.4 nm, and 1.9 nm, respectively. It is suggested that the scavenging effect induced by the metal electrodes is related to the concentration of oxygen vacancies generated by oxidation reaction at the metal/HfO{sub 2} interface.« less

Fabrication of Nanostructured Mesoporous Germanium for Application in Laser Desorption Ionization Mass Spectrometry.

PubMed

Abdelmaksoud, Hazem H; Guinan, Taryn M; Voelcker, Nicolas H

2017-02-15

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a high-throughput analytical technique ideally suited for small-molecule detection from different bodily fluids (e.g., saliva, urine, and blood plasma). Many SALDI-MS substrates require complex fabrication processes and further surface modifications. Furthermore, some substrates show instability upon exposure to ambient conditions and need to be kept under special inert conditions. We have successfully optimized mesoporous germanium (meso-pGe) using bipolar electrochemical etching and efficiently applied meso-pGe as a SALDI-MS substrate for the detection of illicit drugs such as in the context of workplace, roadside, and antiaddictive drug compliance. Argon plasma treatment improved the meso-pGe efficiency as a SALDI-MS substrate and eliminated the need for surface functionalization. The resulting substrate showed a precise surface geometry tuning by altering the etching parameters, and an outstanding performance for illicit drug detection with a limit of detection in Milli-Q water of 1.7 ng/mL and in spiked saliva as low as 5.3 ng/mL for cocaine. The meso-pGe substrate had a demonstrated stability over 56 days stored in ambient conditions. This proof-of-principle study demonstrates that meso-pGe can be reproducibly fabricated and applied as an analytical SALDI-MS substrate which opens the door for further analytical and forensic high-throughput applications.

Three-stage nucleation and growth of Ge self-assembled quantum dots grown on partially relaxed SiGe buffer layers

NASA Astrophysics Data System (ADS)

Kim, H. J.; Zhao, Z. M.; Xie, Y. H.

2003-11-01

Three-stage nucleation and growth of Ge self-assembled quantum dots (SAQDs) on a relaxed SiGe buffer layer has been studied. Plastic relaxation of the SiGe buffer layer is associated with a network of buried 60° dislocations leading to an undulating strain field. As a result, the surface possesses three different types of sites for the nucleation and growth of Ge SAQDs: over the intersection of two perpendicular buried dislocations, over a single dislocation line, and in the region beyond one diffusion length away from any dislocation. Ge SAQDs are observed to nucleate exclusively over the dislocation intersections first, followed by over single dislocation lines, and finally in the region far away from dislocations. By increasing the Ge coverage at a slow rate, the prenucleation stage at the various sites is observed. It appears that the varying strain field has a significant effect on both the diffusion of Ge adatoms before SAQD nucleation, as well as the shape evolution of the SAQDs after they form. Moreover, two distinctly different self-assembly mechanisms are observed at different sites. There exist denuded zones free of Ge SAQDs adjacent to dislocation lines. The width of the denuded zone can be used to make direct determination of the Ge adatom diffusion lengths. The partially relaxed substrate provides a useful experimental vehicle for the in-depth understanding of the formation mechanism of SAQDs grown epitaxially in the Stranski-Krastanov growth mode.

LWIR HgCdTe Detectors Grown on Ge Substrates

NASA Astrophysics Data System (ADS)

Vilela, M. F.; Lofgreen, D. D.; Smith, E. P. G.; Newton, M. D.; Venzor, G. M.; Peterson, J. M.; Franklin, J. J.; Reddy, M.; Thai, Y.; Patten, E. A.; Johnson, S. M.; Tidrow, M. Z.

2008-09-01

Long-wavelength infrared (LWIR) HgCdTe p-on- n double-layer heterojunctions (DLHJs) for infrared detector applications have been grown on 100 mm Ge (112) substrates by molecular beam epitaxy (MBE). The objective of this current work was to grow our baseline p-on- n DLHJ detector structure (used earlier on Si substrates) on 100 mm Ge substrates in the 10 μm to 11 μm LWIR spectral region, evaluate the material properties, and obtain some preliminary detector performance data. Material characterization techniques included are X-ray rocking curves, etch pit density (EPD) measurements, compositional uniformity determined from Fourier-transform infrared (FTIR) transmission, and doping concentrations determined from secondary-ion mass spectroscopy (SIMS). Detector properties include resistance-area product (RoA), spectral response, and quantum efficiency. Results of LWIR HgCdTe detectors and test structure arrays (TSA) fabricated on both Ge and silicon (Si) substrates are presented and compared. Material properties demonstrated include X-ray full-width of half-maximum (FWHM) as low as 77 arcsec, typical etch pit densities in mid 106 cm-2 and wavelength cutoff maximum/minimum variation <2% across the full wafer. Detector characteristics were found to be nearly identical for HgCdTe grown on either Ge or Si substrates.

Growth of single-layer graphene on Ge (1 0 0) by chemical vapor deposition

NASA Astrophysics Data System (ADS)

Mendoza, C. D.; Caldas, P. G.; Freire, F. L.; Maia da Costa, M. E. H.

2018-07-01

The integration of graphene into nanoelectronic devices is dependent on the availability of direct deposition processes, which can provide uniform, large-area and high-quality graphene on semiconductor substrates such as Ge or Si. In this work, we synthesised graphene directly on p-type Ge (1 0 0) substrates by chemical vapour deposition. The influence of the CH4:H2 flow ratio on the graphene growth was investigated. Raman Spectroscopy, Raman mapping, Scanning Electron Microscopy, Atomic Force Microscopy and Scanning Tunnelling Microscopy/Scanning Tunnelling Spectroscopy results showed that good quality and homogeneous monolayer graphene over a large area can be achieved on Ge substrates directly with optimal growth conditions.

Fabrication of Ge-on-insulator wafers by Smart-CutTM with thermal management for undamaged donor Ge wafers

NASA Astrophysics Data System (ADS)

Kim, Munho; Cho, Sang June; Jayeshbhai Dave, Yash; Mi, Hongyi; Mikael, Solomon; Seo, Jung-Hun; Yoon, Jung U.; Ma, Zhenqiang

2018-01-01

Newly engineered substrates consisting of semiconductor-on-insulator are gaining much attention as starting materials for the subsequent transfer of semiconductor nanomembranes via selective etching of the insulating layer. Germanium-on-insulator (GeOI) substrates are critically important because of the versatile applications of Ge nanomembranes (Ge NMs) toward electronic and optoelectronic devices. Among various fabrication techniques, the Smart-CutTM technique is more attractive than other methods because a high temperature annealing process can be avoided. Another advantage of Smart-CutTM is the reusability of the donor Ge wafer. However, it is very difficult to realize an undamaged Ge wafer because there exists a large mismatch in the coefficient of thermal expansion among the layers. Although an undamaged donor Ge wafer is a prerequisite for its reuse, research related to this issue has not yet been reported. Here we report the fabrication of 4-inch GeOI substrates using the direct wafer bonding and Smart-CutTM process with a low thermal budget. In addition, a thermo-mechanical simulation of GeOI was performed by COMSOL to analyze induced thermal stress in each layer of GeOI. Crack-free donor Ge wafers were obtained by annealing at 250 °C for 10 h. Raman spectroscopy and x-ray diffraction (XRD) indicated similarly favorable crystalline quality of the Ge layer in GeOI compared to that of bulk Ge. In addition, Ge p-n diodes using transferred Ge NM indicate a clear rectifying behavior with an on and off current ratio of 500 at ±1 V. This demonstration offers great promise for high performance transferrable Ge NM-based device applications.

Nucleation sites of Ge nanoislands grown on pit-patterned Si substrate prepared by electron-beam lithography

NASA Astrophysics Data System (ADS)

Smagina, Zh. V.; Zinovyev, V. A.; Rudin, S. A.; Novikov, P. L.; Rodyakina, E. E.; Dvurechenskii, A. V.

2018-04-01

Regular pit-patterned Si(001) substrates were prepared by electron-beam lithography followed by plasma chemical etching. The geometry of the pits was controlled by varying the etching conditions and the electron-beam exposure duration. It was shown that the location of three-dimensional (3D) Ge nanoislands subsequently grown on the pit-patterned Si substrates depends on the shape of the pit bottom. In the case of pits having a sharp bottom, 3D Ge islands nucleate inside the pits. For pits with a wide flat bottom, the 3D Ge island nucleation takes place at the pit periphery. This effect is attributed to the strain relaxation depending not only on the initial pit shape, but also on its evolution during the Ge wetting layer deposition. It was shown by Monte Carlo simulations that in the case of a pit with a pointed bottom, the relaxation is most effective inside the pit, while for a pit with a wide bottom, the most relaxed area migrates during Ge deposition from the pit bottom to its edges, where 3D Ge islands nucleate.

A promising routine to fabricate GeSi nanowires via self-assembly on miscut Si (001) substrates.

PubMed

Zhong, Zhenyang; Gong, Hua; Ma, Yingjie; Fan, Yongliang; Jiang, Zuimin

2011-04-11

: Very small and compactly arranged GeSi nanowires could self-assembled on vicinal Si (001) substrates with ~8° off toward ⟨110⟩ during Ge deposition. The nanowires were all oriented along the miscut direction. The small ration of height over width of the nanowire indicated that the nanowires were bordered partly with {1 0 5} facets. These self-assembled small nanowires were remarkably influenced by the growth conditions and the miscut angle of substrates in comparison with large dome-like islands obtained after sufficient Ge deposition. These results proposed that the formation of the nanowire was energetically driven under growth kinetic assistance. Three-dimensionally self-assembled GeSi nanowires were first realized via multilayer Ge growth separated with Si spacers. These GeSi nanowires were readily embedded in Si matrix and compatible with the sophisticated Si technology, which suggested a feasible strategy to fabricate nanowires for fundamental studies and a wide variety of applications.PACS: 81.07.Gf, 81.16.Dn, 68.65.-k, 68.37.Ps.

Strain-Engineered Nanomembrane Substrates for Si/SiGe Heterostructures

NASA Astrophysics Data System (ADS)

Sookchoo, Pornsatit

For Group IV materials, including silicon, germanium, and their alloys, although they are most widely used in the electronics industry, the development of photonic devices is hindered by indirect band gaps and large lattice mismatches. Thus, any heterostructures involving Si and Ge (4.17% lattice mismatch) are subject to plastic relaxation by dislocation formation in the heterolayers. These defects make many devices impossible and at minimum degrade the performance of those that are possible. Fabrication using elastic strain engineering in Si/SiGe nanomembranes (NMs) is an approach that is showing promise to overcome this limitation. A key advantage of such NM substrates over conventional bulk substrates is that they are relaxed elastically and therefore free of dislocations that occur in the conventional fabrication of SiGe substrates, which are transferred to the epilayers and roughen film interfaces. In this thesis, I use the strain engineering of NMs or NM stacks to fabricate substrates for the epitaxial growth of many repeating units of Si/SiGe heterostructure, known as a 'superlattice', by the elastic strain sharing of a few periods of the repeating unit of Si/SiGe heterolayers or a Si/SiGe/Si tri-layer structure. In both cases, the process begins with the epitaxial growth of Si/SiGe heterolayers on silicon-on-insulator (SOI), where each layer thickness is designed to stay below its kinetic critical thickness for the formation of dislocations. The heterostructure NMs are then released by etching of the SiO2 sacrificial layer in hydrofluoric acid. The resulting freestanding NMs are elastically relaxed by the sharing of strain between the heterolayers. The NMs can be bonded in-place to their host substrate or transferred to another host substrate for the subsequent growth of many periods of superlattice film. The magnitude of strain sharing in these freestanding NMs is influenced by their layer thicknesses and layer compositions. As illustrated in this dissertation, strain-engineering of such NMs can provide the enabling basis for improved Group IV optoelectronic devices.

Heteroepitaxial growth of Ge films on (100) GaAs by pyrolysis of digermane

NASA Astrophysics Data System (ADS)

Eres, Djula; Lowndes, Douglas H.; Tischler, J. Z.; Sharp, J. W.; Geohegan, D. B.; Pennycook, S. J.

1989-08-01

Pyrolysis of high-purity digermane (Ge2 H6 ) has been used to grow epitaxial Ge films of high crystalline quality on (100) GaAs substrates in a low-pressure environment. X-ray double-crystal diffractometry shows that fully commensurate, coherently strained epitaxial Ge films can be grown on (100) GaAs at digermane partial pressures of 0.05-40 mTorr for substrate temperatures of 380-600 °C. Amorphous films also were deposited. Information about the crystalline films surface morphology, growth mode, and microstructure was obtained from scanning electron microscopy, cross-section transmission electron microscopy, and in situ reflectivity measurements. The amorphous-to-crystalline transition temperature and the morphology of the crystalline films were both found to depend on deposition conditions (primarily the incidence rate of Ge-bearing species and the substrate temperature). Epitaxial growth rates using digermane were found to be about two orders of magnitude higher than rates using germane (GeH4 ) under similar experimental conditions.

STM studies of GeSi thin layers epitaxially grown on Si(111)

NASA Astrophysics Data System (ADS)

Motta, N.; Sgarlata, A.; De Crescenzi, M.; Derrien, J.

1996-08-01

Ge/Si alloys were prepared in UHV by solid phase epitaxy on Si(111) substrates. The alloy formation, as a function of the evaporation rate and the Ge layer thickness has been followed in situ by RHEED and scanning tunneling microscopy. The 5 × 5 surface reconstruction appeared after annealing at 450°C Ge layers (up to 10 Å thick), obtained from a low rate Knudsen cell evaporator. In this case a nearly flat and uniform layer of reconstructed alloy was observed. When using an e-gun high rate evaporator we needed to anneal the Ge layer up to 780°C to obtain a 5 × 5 reconstruction. The grown layer was not flat, with many steps and Ge clusters; at high coverages (10 Å and more) large Ge islands appeared. Moreover, we then succeeded in visualizing at atomic resolution the top of some of these Ge islands which displayed a 2 × 1 reconstruction, probably induced from the high compressive strain due to the lattice mismatch with the substrate. We suggest that this unusual behavior could be connected to the high evaporation rate, which helped the direct formation of Ge microcrystals on the Si substrate during the deposition process.

Formation of Si and Ge films and micropatterns by wet process using laser direct writing method

NASA Astrophysics Data System (ADS)

Watanabe, Akira

2011-03-01

The studies toward the formation of Si and Ge films and micropatterns by wet process using laser direct writing method are reported. First is the the formation of Si film by laser scanning irradiation to Si nano- or micro-particle dispersed films. By using organogermanium nanocluster (OrGe) as a dispersion medium of Si particles, a homogeneous Si film was formed by laser scanning irradiation on a Si particle/OrGe composite film. The micro-Raman spectra showed the formation of the polycrystalline Ge and SiGe alloy during the fusion of the Si particles by laser irradiation. The second is the formation of the Si and Ge micropatterns by LLDW (liquid phase laser direct writing) method. Micro-Raman spectra showed the formation of polycrystalline Si and Ge micropatterns by laser irradiation on the interfaces of SiCl4/substrate and GeCl4/substrate, respectively.

Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe by solid-liquid-coexisting annealing of a-GeSn/c-Si structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadoh, Taizoh, E-mail: sadoh@ed.kyushu-u.ac.jp; Chikita, Hironori; Miyao, Masanobu

2015-09-07

Ultra-low temperature (≤300 °C) growth of Ge-rich SiGe on Si substrates is strongly desired to realize advanced electronic and optical devices, which can be merged onto Si large-scale integrated circuits (LSI). To achieve this, annealing characteristics of a-GeSn/c-Si structures are investigated under wide ranges of the initial Sn concentrations (0%–26%) and annealing conditions (300–1000 °C, 1 s–48 h). Epitaxial growth triggered by SiGe mixing is observed after annealing, where the annealing temperatures necessary for epitaxial growth significantly decrease with increasing initial Sn concentration and/or annealing time. As a result, Ge-rich (∼80%) SiGe layers with Sn concentrations of ∼2% are realized by ultra-low temperature annealingmore » (300 °C, 48 h) for a sample with the initial Sn concentration of 26%. The annealing temperature (300 °C) is in the solid-liquid coexisting temperature region of the phase diagram for Ge-Sn system. From detailed analysis of crystallization characteristics and composition profiles in grown layers, it is suggested that SiGe mixing is generated by a liquid-phase reaction even at ultra-low temperatures far below the melting temperature of a-GeSn. This ultra-low-temperature growth technique of Ge-rich SiGe on Si substrates is expected to be useful to realize next-generation LSI, where various multi-functional devices are integrated on Si substrates.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drozdov, Yu. N., E-mail: drozdyu@ipmras.ru; Drozdov, M. N.; Yunin, P. A.

It is demonstrated using X-ray diffraction and atomic force microscopy that elastic stresses in GeSi layers on Si (115) substrates relax more effectively than in the same layers on Si (001) substrates. This fact is attributed to the predominant contribution of one of the (111) slip planes on the (115) cut. The atomicforce-microscopy image of the GeSi/Si(115) surface reveals unidirectional slip planes, while the GeSi/Si(001) image contains a grid of orthogonal lines and defects at the points of their intersection. As a result, thick GeSi layers on Si (115) have a reduced surface roughness. A technique for calculating the parametersmore » of relaxation of the layer on the Si (115) substrate using X-ray diffraction data is discussed.« less

Superconducting articles of manufacture and method of producing same

DOEpatents

Newkirk, Lawrence R.; Valencia, Flavio A.

1980-01-01

Bulk coatings of Nb.sub.3 Ge with high superconducting transition temperatures bonded to metallic substrates and a chemical vapor deposition method for producing such coatings on metallic substrates are disclosed. In accordance with the method, a Nb.sub.3 Ge coating having a transition temperature in excess of 21.5 K may be tightly bonded to a copper substrate.

Mid-infrared intersubband absorption from p-Ge quantum wells grown on Si substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gallacher, K.; Millar, R. W.; Paul, D. J., E-mail: Douglas.Paul@glasgow.ac.uk

2016-02-29

Mid-infrared intersubband absorption from p-Ge quantum wells with Si{sub 0.5}Ge{sub 0.5} barriers grown on a Si substrate is demonstrated from 6 to 9 μm wavelength at room temperature and can be tuned by adjusting the quantum well thickness. Fourier transform infra-red transmission and photoluminescence measurements demonstrate clear absorption peaks corresponding to intersubband transitions among confined hole states. The work indicates an approach that will allow quantum well intersubband photodetectors to be realized on Si substrates in the important atmospheric transmission window of 8–13 μm.

Substrate effects on the epitaxial growth of ZnGeP2 thin films by open tube organometallic chemical vapor deposition

NASA Technical Reports Server (NTRS)

Xing, G. C.; Bachmann, K. J.; Posthill, J. B.; Timmons, M. L.

1991-01-01

Epitaxial ZnGeP2-Ge films have been grown on (111)GaP substrates using MOCVD. The films grown with dimethylzinc to germane flow rate ratio R greater than 10 show mirror-smooth surface morphology. Films grown with R less than 10 show a high density of twinning, including both double position and growth twins. Compared to films grown on (001) GaP substrates, the layers on (111) GaP generally show a higher density of microstructural defects. TEM electron diffraction patterns show that the films grown on (111) GaP substrates are more disordered than films grown on (001) GaP under comparable conditions. The growth rate on (111) GaP substrates is about 2.5 times slower than that on (001) GaP, and films grown on Si substrates show extensive twinning formation. Both TEM and SEM examinations indicate that smooth epitaxial overgrowth may be easier on (111) Si substrates than on (001) Si.

Misfit-guided self-organization of anticorrelated Ge quantum dot arrays on Si nanowires.

PubMed

Kwon, Soonshin; Chen, Zack C Y; Kim, Ji-Hun; Xiang, Jie

2012-09-12

Misfit-strain guided growth of periodic quantum dot (QD) arrays in planar thin film epitaxy has been a popular nanostructure fabrication method. Engineering misfit-guided QD growth on a nanoscale substrate such as the small curvature surface of a nanowire represents a new approach to self-organized nanostructure preparation. Perhaps more profoundly, the periodic stress underlying each QD and the resulting modulation of electro-optical properties inside the nanowire backbone promise to provide a new platform for novel mechano-electronic, thermoelectronic, and optoelectronic devices. Herein, we report a first experimental demonstration of self-organized and self-limited growth of coherent, periodic Ge QDs on a one-dimensional Si nanowire substrate. Systematic characterizations reveal several distinctively different modes of Ge QD ordering on the Si nanowire substrate depending on the core diameter. In particular, Ge QD arrays on Si nanowires of around 20 nm diameter predominantly exhibit an anticorrelated pattern whose wavelength agrees with theoretical predictions. The correlated pattern can be attributed to propagation and correlation of misfit strain across the diameter of the thin nanowire substrate. The QD array growth is self-limited as the wavelength of the QDs remains unchanged even after prolonged Ge deposition. Furthermore, we demonstrate a direct kinetic transformation from a uniform Ge shell layer to discrete QD arrays by a postgrowth annealing process.

Graded Index Silicon Geranium on Lattice Matched Silicon Geranium Semiconductor Alloy

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Elliott, James R., Jr. (Inventor); Stoakley, Diane M. (Inventor)

2009-01-01

A lattice matched silicon germanium (SiGe) semiconductive alloy is formed when a {111} crystal plane of a cubic diamond structure SiGe is grown on the {0001} C-plane of a single crystalline Al2O3 substrate such that a <110> orientation of the cubic diamond structure SiGe is aligned with a <1,0,-1,0> orientation of the {0001} C-plane. A lattice match between the substrate and the SiGe is achieved by using a SiGe composition that is 0.7223 atomic percent silicon and 0.2777 atomic percent germanium. A layer of Si(1-x), ,Ge(x) is formed on the cubic diamond structure SiGe. The value of X (i) defines an atomic percent of germanium satisfying 0.2277

Characteristics of Ge-Sb-Te films prepared by cyclic pulsed plasma-enhanced chemical vapor deposition.

PubMed

Suk, Kyung-Suk; Jung, Ha-Na; Woo, Hee-Gweon; Park, Don-Hee; Kim, Do-Heyoung

2010-05-01

Ge-Sb-Te (GST) thin films were deposited on TiN, SiO2, and Si substrates by cyclic-pulsed plasma-enhanced chemical vapor deposition (PECVD) using Ge{N(CH3)(C2H5)}, Sb(C3H7)3, Te(C3H7)3 as precursors in a vertical flow reactor. Plasma activated H2 was used as the reducing agent. The growth behavior was strongly dependent on the type of substrate. GST grew as a continuous film on TiN regardless of the substrate temperature. However, GST formed only small crystalline aggregates on Si and SiO2 substrates, not a continuous film, at substrate temperatures > or = 200 degrees C. The effects of the deposition temperature on the surface morphology, roughness, resistivity, crystallinity, and composition of the GST films were examined.

Selective epitaxial growth of Ge1-xSnx on Si by using metal-organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Washizu, Tomoya; Ike, Shinichi; Inuzuka, Yuki; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

2017-06-01

Selective epitaxial growth of Ge and Ge1-xSnx layers on Si substrates was performed by using metal-organic chemical vapor deposition (MOCVD) with precursors of tertiary-butyl-germane (t-BGe) and tri-butyl-vinyl-tin (TBVSn). We investigated the effects of growth temperature and total pressure during growth on the selectivity and the crystallinity of the Ge and Ge1-xSnx epitaxial layers. Under low total pressure growth conditions, the dominant mechanism of the selective growth of Ge epitaxial layers is the desorption of the Ge precursors. At a high total pressure case, it is needed to control the surface migration of precursors to realize the selectivity because the desorption of Ge precursors was suppressed. The selectivity of Ge growth was improved by diffusion of the Ge precursors on the SiO2 surfaces when patterned substrates were used at a high total pressure. The selective epitaxial growth of Ge1-xSnx layer was also realized using MOCVD. We found that the Sn precursors less likely to desorb from the SiO2 surfaces than the Ge precursors.

DC heating induced shape transformation of Ge structures on ultraclean Si(5 5 12) surfaces.

PubMed

Dash, J K; Rath, A; Juluri, R R; Raman, P Santhana; Müller, K; Rosenauer, A; Satyam, P V

2011-04-06

We report the growth of Ge nanostructures and microstructures on ultraclean, high vicinal angle silicon surfaces and show that self-assembled growth at optimum thickness of the overlayer leads to interesting shape transformations, namely from nanoparticle to trapezoidal structures, at higher thickness values. Thin films of Ge of varying thickness from 3 to 12 ML were grown under ultrahigh vacuum conditions on a Si(5 5 12) substrate while keeping the substrate at a temperature of 600 °C. The substrate heating was achieved by two methods: (i) by heating a filament under the substrate (radiative heating, RH) and (ii) by passing direct current through the samples in three directions (perpendicular, parallel and at 45° to the (110) direction of the substrate). We find irregular, more spherical-like island structures under RH conditions. The shape transformations have been found under DC heating conditions and for Ge deposition more than 8 ML thick. The longer sides of the trapezoid structures are found to be along (110) irrespective of the DC current direction. We also show the absence of such a shape transformation in the case of Ge deposition on Si(111) substrates. Scanning transmission electron microscopy measurements suggested the mixing of Ge and Si. This has been confirmed with a quantitative estimation of the intermixing using Rutherford backscattering spectrometry (RBS) measurements. The role of DC heating in the formation of aligned structures is discussed. Although the RBS simulations show the presence of a possible SiO(x) layer, under the experimental conditions of the present study, the oxide layer would not play a role in determining the formation of the various structures that were reported here.

The role of Ag buffer layer in Fe islands growth on Ge (111) surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Tsu-Yi, E-mail: phtifu@phy.ntnu.edu.tw; Wu, Jia-Yuan; Jhou, Ming-Kuan

2015-05-07

Sub-monolayer iron atoms were deposited at room temperature on Ge (111)-c(2 × 8) substrates with and without Ag buffer layers. The behavior of Fe islands growth was investigated by using scanning tunneling microscope (STM) after different annealing temperatures. STM images show that iron atoms will cause defects and holes on substrates at room temperature. As the annealing temperature rises, iron atoms pull out germanium to form various kinds of alloyed islands. However, the silver layer can protect the Ag/Ge(111)-(√3×√3) reconstruction from forming defects. The phase diagram shows that ring, dot, and triangular defects were only found on Ge (111)-c(2 × 8) substrates. The kindsmore » of islands found in Fe/Ge system are similar to Fe/Ag/Ge system. It indicates that Ge atoms were pulled out to form islands at high annealing temperatures whether there was a Ag layer or not. But a few differences in big pyramidal or strip islands show that the silver layer affects the development of islands by changing the surface symmetry and diffusion coefficient. The structure characters of various islands are also discussed.« less

Selective growth of Ge1- x Sn x epitaxial layer on patterned SiO2/Si substrate by metal-organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Takeuchi, Wakana; Washizu, Tomoya; Ike, Shinichi; Nakatsuka, Osamu; Zaima, Shigeaki

2018-01-01

We have investigated the selective growth of a Ge1- x Sn x epitaxial layer on a line/space-patterned SiO2/Si substrate by metal-organic chemical vapor deposition. We examined the behavior of a Sn precursor of tributyl(vinyl)tin (TBVSn) during the growth on Si and SiO2 substrates and investigated the effect of the Sn precursor on the selective growth. The selective growth of the Ge1- x Sn x epitaxial layer was performed under various total pressures and growth temperatures of 300 and 350 °C. The selective growth of the Ge1- x Sn x epitaxial layer on the patterned Si region is achieved at a low total pressure without Ge1- x Sn x growth on the SiO2 region. In addition, we found that the Sn content in the Ge1- x Sn x epitaxial layer increases with width of the SiO2 region for a fixed Si width even with low total pressure. To control the Sn content in the selective growth of the Ge1- x Sn x epitaxial layer, it is important to suppress the decomposition and migration of Sn and Ge precursors.

Germanium growth on electron beam lithography patterned Si3N4/Si(001) substrate using molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Sarkar, Subhendu Sinha; Katiyar, Ajit K.; Sarkar, Arijit; Dhar, Achintya; Rudra, Arun; Khatri, Ravinder K.; Ray, Samit Kumar

2018-04-01

It is important to investigate the growth dynamics of Ge adatoms under different surface stress regimes of the patterned dielectric to control the selective growth of self-assembled Ge nanostructures on silicon. In the present work, we have studied the growth of Ge by molecular beam epitaxy on nanometer scale patterned Si3N4/Si(001) substrates generated using electron beam lithography. The pitch of the patterns has been varied to investigate its effect on the growth of Ge in comparison to un-patterned Si3N4. For the patterned Si3N4 film, Ge did not desorbed completely from the Si3N4 film and hence no site selective growth pattern is observed. Instead, depending upon the pitch, Ge growth has occurred in different growth modes around the openings in the Si3N4. For the un-patterned substrate, the morphology exhibits the occurrence of uniform 3D clustering of Ge adatoms on Si3N4 film. This variation in the growth modes of Ge is attributed to the variation of residual stress in the Si3N4 film for different pitch of holes, which has been confirmed theoretically through Comsol Multiphysics simulation. The variation in stress for different pitches resulted in modulation of surface energy of the Si3N4 film leading to the different growth modes of Ge.

New Cu(GeNx) film in barrierless metallization for LED heat dissipation

NASA Astrophysics Data System (ADS)

Lin, Chon-Hsin

2015-05-01

In this study, we explore new Cu(Ge) and Cu(GeNx) films for LED heat dissipation. The films are Cu-alloy seed layers, fabricated by co-sputtering Cu and Ge in an Ar or N2 atmosphere on either Ta/Al2O3 or polyimide substrates. The Cu alloy films are then annealed at 600 and 730 °C, respectively, for 1 h without notable Cu oxide formation at the Cu-Ta/Al2O3 interface. No Cu oxide is formed at the Cu-polyimide interface either after annealing the films at 310 °C for 1 h. The film formed atop an Al2O3 substrate contains a trace amount of GeNx and is thermally stable up to 730 °C, and the film formed atop a polyimide substrate is thermally stable up to 310 °C, both exhibiting a low resistivity and a high thermal conductivity. Such a thermal feature makes the Cu(GeNx) film a good candidate material in barrierless metallization for many industrial applications, such as LED heat sinks.

High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate.

PubMed

Li, Chong; Xue, ChunLai; Liu, Zhi; Cong, Hui; Cheng, Buwen; Hu, Zonghai; Guo, Xia; Liu, Wuming

2016-06-09

Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effect is overcome and the thermal effects is suppressed. High current is beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in many applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. When the transmission of the monolayer anti-reflection coating was maximum, the maximum absorption efficiency of the devices was 1.45 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer.

Initial growth processes in the epitaxy of Ge with GeH{sub 4} on oxidized Si substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angermeier, D.; Kuhn, W.S.; Druihle, R.

1997-02-01

The heteroepitaxial growth of Ge on (100) Si in a horizontal, atmospheric pressure metallorganic vapor-phase epitaxy reactor is reported using germane GeH{sub 4} (0.1% in H{sub 2}). A particularly crucial parameter for germanium deposition on silicon is the time for the onset of epitaxial growth, the incubation time. The time was measured at substrate temperatures between 450 and 600{degree}C. At a substrate temperature of 450{degree}C an incubation time of 520 s was found and for the subsequent epitaxy growth rates of 50 nm/min were determined by Nomarski microscopy and electron diffraction. The existence of residual oxide in the reactor chambermore » forming an in situ SiO{sub 2} layer was evaluated by x-ray photoemission spectroscopy. To obtain a more thorough understanding of the gas- and solid-phase composition of Ge, Si, and oxygen the Gibbs energy of the system was calculated for various growth temperatures. It was concluded that SiO{sub 2} molecules are reduced by GeH{sub 4} molecules during the incubation period.« less

High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate

PubMed Central

Li, Chong; Xue, ChunLai; Liu, Zhi; Cong, Hui; Cheng, Buwen; Hu, Zonghai; Guo, Xia; Liu, Wuming

2016-01-01

Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effect is overcome and the thermal effects is suppressed. High current is beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in many applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. When the transmission of the monolayer anti-reflection coating was maximum, the maximum absorption efficiency of the devices was 1.45 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer. PMID:27279426

Silver photo-diffusion and photo-induced macroscopic surface deformation of Ge{sub 33}S{sub 67}/Ag/Si substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakaguchi, Y., E-mail: y-sakaguchi@cross.or.jp; Asaoka, H.; Uozumi, Y.

2016-08-07

Ge-chalcogenide films show various photo-induced changes, and silver photo-diffusion is one of them which attracts lots of interest. In this paper, we report how silver and Ge-chalcogenide layers in Ge{sub 33}S{sub 67}/Ag/Si substrate stacks change under light exposure in the depth by measuring time-resolved neutron reflectivity. It was found from the measurement that Ag ions diffuse all over the matrix Ge{sub 33}S{sub 67} layer once Ag dissolves into the layer. We also found that the surface was macroscopically deformed by the extended light exposure. Its structural origin was investigated by a scanning electron microscopy.

Disentangling nonradiative recombination processes in Ge micro-crystals on Si substrates

NASA Astrophysics Data System (ADS)

Pezzoli, Fabio; Giorgioni, Anna; Gallacher, Kevin; Isa, Fabio; Biagioni, Paolo; Millar, Ross W.; Gatti, Eleonora; Grilli, Emanuele; Bonera, Emiliano; Isella, Giovanni; Paul, Douglas J.; Miglio, Leo

2016-06-01

We address nonradiative recombination pathways by leveraging surface passivation and dislocation management in μm-scale arrays of Ge crystals grown on deeply patterned Si substrates. The time decay photoluminescence (PL) at cryogenic temperatures discloses carrier lifetimes approaching 45 ns in band-gap engineered Ge micro-crystals. This investigation provides compelling information about the competitive interplay between the radiative band-edge transitions and the trapping of carriers by dislocations and free surfaces. Furthermore, an in-depth analysis of the temperature dependence of the PL, combined with capacitance data and finite difference time domain modeling, demonstrates the effectiveness of GeO2 in passivating the surface of Ge and thus in enhancing the room temperature PL emission.

Black GE based on crystalline/amorphous core/shell nanoneedle arrays

DOEpatents

Javey, Ali; Chueh, Yu-Lun; Fan, Zhiyong

2014-03-04

Direct growth of black Ge on low-temperature substrates, including plastics and rubber is reported. The material is based on highly dense, crystalline/amorphous core/shell Ge nanoneedle arrays with ultrasharp tips (.about.4 nm) enabled by the Ni catalyzed vapor-solid-solid growth process. Ge nanoneedle arrays exhibit remarkable optical properties. Specifically, minimal optical reflectance (<1%) is observed, even for high angles of incidence (.about.75.degree.) and for relatively short nanoneedle lengths (.about.1 .mu.m). Furthermore, the material exhibits high optical absorption efficiency with an effective band gap of .about.1 eV. The reported black Ge can have important practical implications for efficient photovoltaic and photodetector applications on nonconventional substrates.

Metabolic inactivation of five glycidyl ethers in lung and liver of humans, rats and mice in vitro.

PubMed

Boogaard, P J; de Kloe, K P; Bierau, J; Kuiken, G; Borkulo, P E; Watson, W P; van Sittert, N J

2000-05-01

1. Some glycidyl ethers (GE) have been shown to be direct mutagens in short-term in vitro tests and consequently GE are considered to be potentially mutagenic in vivo. However, GE may be metabolically inactivated in the body by two different enzymatic routes: conjugation of the epoxide moiety with the endogenous tripeptide glutathione (GSH) catalysed by glutathione S-transferase (GST) or hydrolysis of the epoxide moiety catalysed by epoxide hydrolase (EH). 2. The metabolic inactivation of five different GE, the diglycidyl ethers of bisphenol A (BADGE), 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl (Epikote YX4000) and 1,6-hexanediol (HDDGE) and the GE of 1-dodecanol (C12GE) and o-cresol (o-CGE), has been studied in subcellular fractions of human, C3H mouse and F344 rat liver and lung. 3. All GE were chemically very stable and resistant to aqueous hydrolysis, but were rapidly hydrolysed by EH in cytosolic and microsomal fractions of liver and lung. The aromatic GE were very good substrates for EH. In general, microsomal EH is more efficient than cytosolic EH in hydrolysis of GE, and human microsomes are more efficient than rodent microsomes. 4. The more water-soluble GE, o-CGE and HDDGE, were good substrates for GST whereas the more lipophilic GE, YX4000 and C12GE, were poor substrates for GST. In general, rodents are more efficient in GSH conjugation of GE than humans. 5. In general, the epoxide groups of YX4000 are the most and those of HDDGE the least efficiently inactivated of the five GE under study. For the other three GE no general trend was observed: the relative efficiency of inactivation varied with organ and species. 6. The large variation in metabolism observed with five representative GE indicate that GE have variable individual properties and should not be considered as a single, homogenous class of compounds.

Zn2GeO4 nanowires as efficient electron injection material for electroluminescent devices.

PubMed

Wang, Jiangxin; Yan, Chaoyi; Magdassi, Shlomo; Lee, Pooi See

2013-08-14

Pure phase Zn2GeO4 nanowires (NWs) were grown by the chemical vapor transport method on p-GaN: Mg/Al2O3 substrate. The as-grown Zn2GeO4 NWs exhibited n-type characteristic due to native defects and formed a p-n heterojunction with the p-GaN substrate. The unique energy level of Zn2GeO4 NWs promotes electron injection into GaN active region while suppressing hole injection into Zn2GeO4 NWs. The device exhibited an emission centered at 426 nm and a low turn-on voltage around 4 V. Zn2GeO4 NWs are first reported in this paper as promising electron transport and injection material for electroluminescent devices.

Enhanced photoluminescence of multilayer Ge quantum dots on Si(001) substrates by increased overgrowth temperature.

PubMed

Liu, Zhi; Cheng, Buwen; Hu, Weixuan; Su, Shaojian; Li, Chuanbo; Wang, Qiming

2012-07-11

Four-bilayer Ge quantum dots (QDs) with Si spacers were grown on Si(001) substrates by ultrahigh vacuum chemical vapor deposition. In three samples, all Ge QDs were grown at 520 °C, while Si spacers were grown at various temperatures (520 °C, 550 °C, and 580 °C). Enhancement and redshift of room temperature photoluminescence (PL) were observed from the samples in which Si spacers were grown at a higher temperature. The enhancement of PL is explained by higher effective electrons capturing in the larger size Ge QDs. Quantum confinement of the Ge QDs is responsible for the redshift of PL spectra. The Ge QDs' size and content were investigated by atomic force microscopy and Raman scattering measurements.

Formation of ultrathin Ni germanides: solid-phase reaction, morphology and texture

NASA Astrophysics Data System (ADS)

van Stiphout, K.; Geenen, F. A.; De Schutter, B.; Santos, N. M.; Miranda, S. M. C.; Joly, V.; Detavernier, C.; Pereira, L. M. C.; Temst, K.; Vantomme, A.

2017-11-01

The solid-phase reaction of ultrathin (⩽10 nm) Ni films with different Ge substrates (single-crystalline (1 0 0), polycrystalline, and amorphous) was studied. As thickness goes down, thin film texture becomes a dominant factor in both the film’s phase formation and morphological evolution. As a consequence, certain metastable microstructures are epitaxially stabilized on crystalline substrates, such as the ɛ-Ni5Ge3 phase or a strained NiGe crystal structure on the single-crystalline substrates. Similarly, the destabilizing effect of axiotaxial texture on the film’s morphology becomes more pronounced as film thicknesses become smaller. These effects are contrasted by the evolution of germanide films on amorphous substrates, on which neither epitaxy nor axiotaxy can form, i.e. none of the (de)stabilizing effects of texture are observed. The crystallization of such amorphous substrates however, drives the film breakup.

Structural and optical characteristics of GaAs films grown on Si/Ge substrates

NASA Astrophysics Data System (ADS)

Rykov, A. V.; Dorokhin, M. V.; Vergeles, P. S.; Baidus, N. V.; Kovalskiy, V. A.; Yakimov, E. B.; Soltanovich, O. A.

2018-03-01

A GaAs/AlAs heterostructure and a GaAs film grown on Si/Ge substrates have been fabricated and studied. A Ge buffer on a silicon substrate was fabricated using the MBE process. A3B5 films were grown by MOCVD at low pressures. Photoluminescence spectroscopy was used to define the optical quality of A3B5 films. Structural properties were investigated using the electron beam induced current method. It was established that despite a rather high density of dislocations on the epitaxial layers, the detected photoluminescence radiation of layers indicates the acceptable crystalline quality of the top GaAs layer.

Ag-NP@Ge-nanotaper/Si-micropillar ordered arrays as ultrasensitive and uniform surface enhanced Raman scattering substrates

NASA Astrophysics Data System (ADS)

Liu, Jing; Meng, Guowen; Li, Zhongbo; Huang, Zhulin; Li, Xiangdong

2015-10-01

Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment.Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) ``hot spots'' created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10-7 M and 10-5 M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06001j

Local epitaxial growth of ZrO2 on Ge (100) substrates by atomic layer epitaxy

NASA Astrophysics Data System (ADS)

Kim, Hyoungsub; Chui, Chi On; Saraswat, Krishna C.; McIntyre, Paul C.

2003-09-01

High-k dielectric deposition processes for gate dielectric preparation on Si surfaces usually result in the unavoidable and uncontrolled formation of a thin interfacial oxide layer. Atomic layer deposition of ˜55-Å ZrO2 film on a Ge (100) substrate using ZrCl4 and H2O at 300 °C was found to produce local epitaxial growth [(001) Ge//(001) ZrO2 and [100] Ge//[100] ZrO2] without a distinct interfacial layer, unlike the situation observed when ZrO2 is deposited using the same method on Si. Relatively large lattice mismatch (˜10%) between ZrO2 and Ge produced a high areal density of interfacial misfit dislocations. Large hysteresis (>200 mV) and high frequency dispersion were observed in capacitance-voltage measurements due to the high density of interface states. However, a low leakage current density, comparable to values obtained on Si substrates, was observed with the same capacitance density regardless of the high defect density.

Evaluation of four inch diameter VGF-Ge substrates used for manufacturing multi-junction solar cell

NASA Astrophysics Data System (ADS)

Kewei, Cao; Tong, Liu; Jingming, Liu; Hui, Xie; Dongyan, Tao; Youwen, Zhao; Zhiyuan, Dong; Feng, Hui

2016-06-01

Low dislocation density Ge wafers grown by a vertical gradient freeze (VGF) method used for the fabrication of multi-junction photovoltaic cells (MJC) have been studied by a whole wafer scale measurement of the lattice parameter, X-ray rocking curves, etch pit density (EPD), impurities concentration, minority carrier lifetime and residual stress. Impurity content in the VGF-Ge wafers, including that of B, is quite low although B2O3 encapsulation is used in the growth process. An obvious difference exists across the whole wafer regarding the distribution of etch pit density, lattice parameter, full width at half maximum (FWHM) of the X-ray rocking curve and residual stress measured by Raman spectra. These are in contrast to a reference Ge substrate wafer grown by the Cz method. The influence of the VGF-Ge substrate on the performance of the MJC is analyzed and evaluated by a comparison of the statistical results of cell parameters. Project supported by the National Natural Science Foundation of China (No. 61474104).

High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation

NASA Technical Reports Server (NTRS)

Alterovitz, S. A.; Mueller, C. H.; Croke, E. T.

2003-01-01

High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.

GaAs/Ge crystals grown on Si substrates patterned down to the micron scale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taboada, A. G., E-mail: gonzalez@phys.ethz.ch; Kreiliger, T.; Falub, C. V.

Monolithic integration of III-V compounds into high density Si integrated circuits is a key technological challenge for the next generation of optoelectronic devices. In this work, we report on the metal organic vapor phase epitaxy growth of strain-free GaAs crystals on Si substrates patterned down to the micron scale. The differences in thermal expansion coefficient and lattice parameter are adapted by a 2-μm-thick intermediate Ge layer grown by low-energy plasma enhanced chemical vapor deposition. The GaAs crystals evolve during growth towards a pyramidal shape, with lateral facets composed of (111) planes and an apex formed by (137) and (001) surfaces.more » The influence of the anisotropic GaAs growth kinetics on the final morphology is highlighted by means of scanning and transmission electron microscopy measurements. The effect of the Si pattern geometry, substrate orientation, and crystal aspect ratio on the GaAs structural properties was investigated by means of high resolution X-ray diffraction. The thermal strain relaxation process of GaAs crystals with different aspect ratio is discussed within the framework of linear elasticity theory by Finite Element Method simulations based on realistic geometries extracted from cross-sectional scanning electron microscopy images.« less

Atomic Layer Deposition of HfO2 and Si Nitride on Ge Substrates

NASA Astrophysics Data System (ADS)

Zhu, Shiyang; Nakajima, Anri

2007-12-01

Hafnium oxide (HfO2) thin films were deposited on Ge substrates at 300 °C using atomic layer deposition (ALD) with tetrakis(diethylamino)hafnium (termed as TDEAH) as a precursor and water as an oxidant. The deposition rate was estimated to be 0.09 nm/cycle and the deposited HfO2 films have a smooth surface and an almost stoichiometric composition, indicating that the growth follows a layer-by-layer kinetics, similarly to that on Si substrates. Si nitride thin films were also deposited on Ge by ALD using SiCl4 as a precursor and NH3 as an oxidant. Si nitride has a smaller deposition rate of about 0.055 nm/cycle and a larger gate leakage current than HfO2 deposited on Ge by ALD.

Growth of InN on Ge substrate by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Trybus, Elaissa; Namkoong, Gon; Henderson, Walter; Doolittle, W. Alan; Liu, Rong; Mei, Jin; Ponce, Fernando; Cheung, Maurice; Chen, Fei; Furis, Madalina; Cartwright, Alexander

2005-06-01

InN epitaxial growth on a (1 1 1)-oriented, Ga-doped germanium substrate using molecular beam epitaxy is described. X-ray diffraction and transmission electron microscopy investigations have shown that the InN epitaxial layer consists of a wurtzite structure, which has the epitaxial relationship of (0 0 0 1) InN∥(1 1 1) Ge. Transmission electron microscopy shows an intermediate layer at the interface between the InN/Ge substrate. Consistent with recent reports implying a narrow bandgap of InN [Phys. Stat Sol. B 229 (2002) R1, Appl. Phys. Lett. 80 (2002) 3967], a strong photoluminescence with peak energy of 0.69 eV at 15 K was observed for this InN epilayer, in contrast to the peak energy of 0.71 eV for Ga-doped Ge under the same measurement conditions.

Promising features of low-temperature grown Ge nanostructures on Si(001) substrates

NASA Astrophysics Data System (ADS)

Wang, Ze; Wang, Shuguang; Yin, Yefei; Liu, Tao; Lin, Dongdong; Li, De-hui; Yang, Xinju; Jiang, Zuimin; Zhong, Zhenyang

2017-03-01

High-quality Ge nanostructures are obtained by molecular beam epitaxy of Ge on Si(001) substrates at 200 °C and ex situ annealing at 400 °C. Their structural properties are comprehensively characterized by atomic force microscopy, transmission electron microscopy and Raman spectroscopy. It is disclosed that they are almost defect free except for some defects at the Ge/Si interface and in the subsequent Si capping layer. The misfit strain in the nanostructure is substantially relaxed. Dramatically strong photoluminescence (PL) from the Ge nanostructures is observed. Detailed analyses on the power- and temperature-dependent PL spectra, together with a self-consistent calculation, indicate the confinement and the high quantum efficiency of excitons within the Ge nanostructures. Our results demonstrate that the Ge nanostructures obtained via the present feasible route may have great potential in optoelectronic devices for monolithic optical-electronic integration circuits.

Misfit-guided self-organization of anti-correlated Ge quantum dot arrays on Si nanowires

PubMed Central

Kwon, Soonshin; Chen, Zack C.Y.; Kim, Ji-Hun; Xiang, Jie

2012-01-01

Misfit-strain guided growth of periodic quantum dot (QD) arrays in planar thin film epitaxy has been a popular nanostructure fabrication method. Engineering misfit-guided QD growth on a nanoscale substrate such as the small curvature surface of a nanowire represents a new approach to self-organized nanostructure preparation. Perhaps more profoundly, the periodic stress underlying each QD and the resulting modulation of electro-optical properties inside the nanowire backbone promise to provide a new platform for novel mechano-electronic, thermoelectronic, and optoelectronic devices. Herein, we report a first experimental demonstration of self-organized and self-limited growth of coherent, periodic Ge QDs on a one dimensional Si nanowire substrate. Systematic characterizations reveal several distinctively different modes of Ge QD ordering on the Si nanowire substrate depending on the core diameter. In particular, Ge QD arrays on Si nanowires of around 20 nm diameter predominantly exhibit an anti-correlated pattern whose wavelength agrees with theoretical predictions. The correlated pattern can be attributed to propagation and correlation of misfit strain across the diameter of the thin nanowire substrate. The QD array growth is self-limited as the wavelength of the QDs remains unchanged even after prolonged Ge deposition. Furthermore, we demonstrate a direct kinetic transformation from a uniform Ge shell layer to discrete QD arrays by a post-growth annealing process. PMID:22889063

Crystallization of silicon-germanium by aluminum-induced layer exchange

NASA Astrophysics Data System (ADS)

Isomura, Masao; Yajima, Masahiro; Nakamura, Isao

2018-02-01

We have studied the crystallization of amorphous silicon-germanium (a-SiGe) by aluminum (Al)-induced layer exchange (ALILE) with a starting structure of glass/Al/Al oxide/a-SiGe. We examined ALILE at 450 °C, which is slightly higher than the eutectic temperature of Ge and Al, in order to shorten the ALILE time. We successfully produced c-SiGe films oriented in the (111) direction for 16 h without significant alloying. The thickness of Al layers should be 2800 Å or more to complete the ALILE for the a-SiGe layers of 2000-2800 Å thickness. When the Al layer is as thick as the a-SiGe layer, almost uniform c-SiGe is formed on the glass substrate. On the other hand, the islands of c-SiGe are formed on the glass substrate when the Al layer is thicker than the a-SiGe layer. The islands become smaller with thicker Al layers because more excess Al remains between the SiGe islands. The results indicate that the configuration of c-SiGe can be altered from a uniform structure to island structures of various sizes by changing the ratio of a-SiGe thickness to Al thickness.

Strain Relaxation in Si{sub 1-x}Ge{sub x} Thin Films on Si(100) Substrates: Modeling and Comparisons with Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolluri, K; Zepeda-Ruiz, L A; Murthy, C S

2005-03-22

Strained semiconductor thin films grown epitaxially on semiconductor substrates of different composition, such as Si{sub 1-x}Ge{sub x}/Si, are becoming increasingly important in modern microelectronic technologies. In this paper, we report a hierarchical computational approach for analysis of dislocation formation, glide motion, multiplication, and annihilation in Si{sub 1-x}Ge{sub x} epitaxial thin films on Si substrates. Specifically, a condition is developed for determining the critical film thickness with respect to misfit dislocation generation as a function of overall film composition, film compositional grading, and (compliant) substrate thickness. In addition, the kinetics of strain relaxation in the epitaxial film during growth or thermalmore » annealing (including post-implantation annealing) is analyzed using a properly parameterized dislocation mean-field theoretical model, which describes plastic deformation dynamics due to threading dislocation propagation. The theoretical results for Si{sub 1-x}Ge{sub x} epitaxial thin films grown on Si (100) substrates are compared with experimental measurements and are used to discuss film growth and thermal processing protocols toward optimizing the mechanical response of the epitaxial film.« less

High-performance Ge p-i-n photodetector on Si substrate

NASA Astrophysics Data System (ADS)

Chen, Li-qun; Huang, Xiang-ying; Li, Min; Huang, Yan-hua; Wang, Yue-yun; Yan, Guang-ming; Li, Cheng

2015-05-01

High-performance and tensile-strained germanium (Ge) p-i-n photodetector is demonstrated on Si substrate. The epitaxial Ge layers were prepared in an ultrahigh vacuum chemical vapor deposition (UHV-CVD) system using low temperature Ge buffer technique. The devices were fabricated by in situ doping and using Si as passivation layer between Ge and metal, which can improve the ohmic contact and realize the high doping. The results show that the dark current of the photodetector with diameter of 24 μm is about 2.5×10-7 μA at the bias voltage of -1 V, and the optical responsivity is 0.1 A/W at wavelength of 1.55 μm. The 3 dB bandwidth (BW) of 4 GHz is obtained for the photodetector with diameter of 24 μm at reverse bias voltage of 1 V. The long diffusion time of minority carrier in n-type Ge and the large contact resistance in metal/Ge contacts both affect the performance of Ge photodetectors.

Strain field mapping of dislocations in a Ge/Si heterostructure.

PubMed

Liu, Quanlong; Zhao, Chunwang; Su, Shaojian; Li, Jijun; Xing, Yongming; Cheng, Buwen

2013-01-01

Ge/Si heterostructure with fully strain-relaxed Ge film was grown on a Si (001) substrate by using a two-step process by ultra-high vacuum chemical vapor deposition. The dislocations in the Ge/Si heterostructure were experimentally investigated by high-resolution transmission electron microscopy (HRTEM). The dislocations at the Ge/Si interface were identified to be 90° full-edge dislocations, which are the most efficient way for obtaining a fully relaxed Ge film. The only defect found in the Ge epitaxial film was a 60° dislocation. The nanoscale strain field of the dislocations was mapped by geometric phase analysis technique from the HRTEM image. The strain field around the edge component of the 60° dislocation core was compared with those of the Peierls-Nabarro and Foreman dislocation models. Comparison results show that the Foreman model with a = 1.5 can describe appropriately the strain field around the edge component of a 60° dislocation core in a relaxed Ge film on a Si substrate.

Magnetic properties influenced by interfaces in ultrathin Co/Ge(1 0 0) and Co/Ge(1 1 1) films

NASA Astrophysics Data System (ADS)

Tsay, J. S.; Yao, Y. D.; Cheng, W. C.; Tseng, T. K.; Wang, K. C.; Yang, C. S.

2003-10-01

Magnetic properties influenced by interfaces in ultrathin Co/Ge(1 0 0) and Co/Ge(1 1 1) films with thickness below 28 monolayers (ML) have been studied using the surface magneto-optic Kerr effect (SMOKE) technique. In both systems, the nonferromagnetic layer, as an interface between Co and Ge, plays an important role during annealing. In general, ultrathin Co films with fixed total thickness but fabricated at different temperatures on the same substrate, their Kerr hysteresis loops disappear roughly at the same temperature. This suggests that the thickness of the interfacial layer could inversely prevent the diffusion between Co and Ge substrate. From the annealing studies for both systems with total film thickness of 28 monolayers, we have found that Kerr signal disappears at 375 K for Co/Ge(1 1 1) and 425 K for Co/Ge(1 0 0) films. This suggests that Co/Ge(1 1 1) films possess a lower thermal stability than that of the Co/Ge(1 0 0) films. Our experimental data could be explained by different interfacial condition between Ge(1 0 0) and Ge(1 1 1), the different onset of interdiffusion, and the surface structure condition of Ge(1 0 0) and Ge(1 1 1).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasanah, Lilik, E-mail: lilikhasanah@upi.edu; Suhendi, Endi; Tayubi, Yuyu Rahmat

In this work we discuss the surface roughness of Si interface impact to the tunneling current of the Si/Si{sub 1-x}Ge{sub x}/Si heterojunction bipolar transistor. The Si interface surface roughness can be analyzed from electrical characteristics through the transversal electron velocity obtained as fitting parameter factor. The results showed that surface roughness increase as Ge content of virtual substrate increase This model can be used to investigate the effect of Ge content of the virtual substrate to the interface surface condition through current-voltage characteristic.

Alignment of Ge nanoislands on Si(111) by Ga-induced substrate self-patterning.

PubMed

Schmidt, Th; Flege, J I; Gangopadhyay, S; Clausen, T; Locatelli, A; Heun, S; Falta, J

2007-02-09

A novel mechanism is described which enables the selective formation of three-dimensional Ge islands. Submonolayer adsorption of Ga on Si(111) at high temperature leads to a self-organized two-dimensional pattern formation by separation of the 7 x 7 substrate and Ga/Si(111)-(square root[3] x square root[3])-R30 degrees domains. The latter evolve at step edges and domain boundaries of the initial substrate reconstruction. Subsequent Ge deposition results in the growth of 3D islands which are aligned at the boundaries between bare and Ga-covered domains. This result is explained in terms of preferential nucleation conditions due to a modulation of the surface chemical potential.

Investigation on high-efficiency Ga0.51In0.49P/In0.01Ga0.99As/Ge triple-junction solar cells for space applications

NASA Astrophysics Data System (ADS)

Zhang, Lei; Niu, Pingjuan; Li, Yuqiang; Song, Minghui; Zhang, Jianxin; Ning, Pingfan; Chen, Peizhuan

2017-12-01

Ga0.51In0.49P/In0.01Ga0.99As/Ge triple-junction solar cells for space applications were grown on 4 inch Ge substrates by metal organic chemical vapor deposition methods. The triple-junction solar cells were obtained by optimizing the subcell structure, showing a high open-circuit voltage of 2.77 V and a high conversion efficiency of 31% with 30.15 cm2 area under the AM0 spectrum at 25 °C. In addition, the In0.01Ga0.99As middle subcell structure was focused by optimizing in order to improve the anti radiation ability of triple-junction solar cells, and the remaining factor of conversion efficiency for middle subcell structure was enhanced from 84% to 92%. Finally, the remaining factor of external quantum efficiency for triple-junction solar cells was increased from 80% to 85.5%.

Ag-NP@Ge-nanotaper/Si-micropillar ordered arrays as ultrasensitive and uniform surface enhanced Raman scattering substrates.

PubMed

Liu, Jing; Meng, Guowen; Li, Zhongbo; Huang, Zhulin; Li, Xiangdong

2015-11-21

Surface-enhanced Raman scattering (SERS) is considered to be an excellent candidate for analytical detection schemes, because of its molecular specificity, rapid response and high sensitivity. Here, SERS-substrates of Ag-nanoparticle (Ag-NP) decorated Ge-nanotapers grafted on hexagonally ordered Si-micropillar (denoted as Ag-NP@Ge-nanotaper/Si-micropillar) arrays are fabricated via a combinatorial process of two-step etching to achieve hexagonal Si-micropillar arrays, chemical vapor deposition of flocky Ge-nanotapers on each Si-micropillar and decoration of Ag-NPs onto the Ge-nanotapers through galvanic displacement. With high density three-dimensional (3D) "hot spots" created from the large quantities of the neighboring Ag-NPs and large-scale uniform morphology, the hierarchical Ag-NP@Ge-nanotaper/Si-micropillar arrays exhibit strong and reproducible SERS activity. Using our hierarchical 3D SERS-substrates, both methyl parathion (a commonly used pesticide) and PCB-2 (one congener of highly toxic polychlorinated biphenyls) with concentrations down to 10(-7) M and 10(-5) M have been detected respectively, showing great potential in SERS-based rapid trace-level detection of toxic organic pollutants in the environment.

A new Cu(GeNx) alloy film for industrial applications

NASA Astrophysics Data System (ADS)

Lin, Chon-Hsin

2014-11-01

In this study, a copper alloy [Cu(GeNx)] film is developed for industrial applications by cosputtering Cu and Ge targets on a barrierless Si substrate within a vacuum chamber sparsely filled with N2 gas. Through extensive tests conducted in this study, the alloy film shows good thermal stability and adhesion to the substrate with no noticeable interactions between the film and the substrate after annealing at 720 °C for 1 h. The new Cu(GeNx) alloy film also renders adequate wetting for solders, shows good solderability, and has a dissolution rate lower than pure Cu by at least one order of magnitude, in addition to having a comparable consumption rate to Ni. The alloy film seems suitable for industrial applications in, e.g., barrierless Si metallization, interconnect manufacture and, the replacement of the wetting and diffusion layers for flip-chip solder joints in conventional metallurgy.

Direct growth of Ge quantum dots on a graphene/SiO2/Si structure using ion beam sputtering deposition.

PubMed

Zhang, Z; Wang, R F; Zhang, J; Li, H S; Zhang, J; Qiu, F; Yang, J; Wang, C; Yang, Y

2016-07-29

The growth of Ge quantum dots (QDs) using the ion beam sputtering deposition technique has been successfully conducted directly on single-layer graphene supported by SiO2/Si substrate. The results show that the morphology and size of Ge QDs on graphene can be modulated by tuning the Ge coverage. Charge transfer behavior, i.e. doping effect in graphene has been demonstrated at the interface of Ge/graphene. Compared with that of traditional Ge dots grown on Si substrate, the positions of both corresponding photoluminescence (PL) peaks of Ge QDs/graphene hybrid structure undergo a large red-shift, which can probably be attributed to the lack of atomic intermixing and the existence of surface states in this hybrid material. According to first-principles calculations, the Ge growth on the graphene should follow the so-called Volmer-Weber mode instead of the Stranski-Krastanow one which is observed generally in the traditional Ge QDs/Si system. The calculations also suggest that the interaction between Ge and graphene layer can be enhanced with the decrease of the Ge coverage. Our results may supply a prototype for fabricating novel optoelectronic devices based on a QDs/graphene hybrid nanostructure.

Low temperature thermal ALD of a SiNx interfacial diffusion barrier and interface passivation layer on SixGe1- x(001) and SixGe1- x(110)

NASA Astrophysics Data System (ADS)

Edmonds, Mary; Sardashti, Kasra; Wolf, Steven; Chagarov, Evgueni; Clemons, Max; Kent, Tyler; Park, Jun Hong; Tang, Kechao; McIntyre, Paul C.; Yoshida, Naomi; Dong, Lin; Holmes, Russell; Alvarez, Daniel; Kummel, Andrew C.

2017-02-01

Atomic layer deposition of a silicon rich SiNx layer on Si0.7Ge0.3(001), Si0.5Ge0.5(001), and Si0.5Ge0.5(110) surfaces has been achieved by sequential pulsing of Si2Cl6 and N2H4 precursors at a substrate temperature of 285 °C. XPS spectra show a higher binding energy shoulder peak on Si 2p indicative of SiOxNyClz bonding while Ge 2p and Ge 3d peaks show only a small amount of higher binding energy components consistent with only interfacial bonds, indicating the growth of SiOxNy on the SiGe surface with negligible subsurface reactions. Scanning tunneling spectroscopy measurements confirm that the SiNx interfacial layer forms an electrically passive surface on p-type Si0.70Ge0.30(001), Si0.50Ge0.50(110), and Si0.50Ge0.50(001) substrates as the surface Fermi level is unpinned and the electronic structure is free of states in the band gap. DFT calculations show that a Si rich a-SiO0.4N0,4 interlayer can produce lower interfacial defect density than stoichiometric a-SiO0.8N0.8, substoichiometric a-Si3N2, or stoichiometric a-Si3N4 interlayers by minimizing strain and bond breaking in the SiGe by the interlayer. Metal-oxide-semiconductor capacitors devices were fabricated on p-type Si0.7Ge0.3(001) and Si0.5Ge0.5(001) substrates with and without the insertion of an ALD SiOxNy interfacial layer, and the SiOxNy layer resulted in a decrease in interface state density near midgap with a comparable Cmax value.

Reduced-Pressure Chemical Vapor Deposition Growth of Isolated Ge Crystals and Suspended Layers on Micrometric Si Pillars.

PubMed

Skibitzki, Oliver; Capellini, Giovanni; Yamamoto, Yuji; Zaumseil, Peter; Schubert, Markus Andreas; Schroeder, Thomas; Ballabio, Andrea; Bergamaschini, Roberto; Salvalaglio, Marco; Miglio, Leo; Montalenti, Francesco

2016-10-05

In this work, we demonstrate the growth of Ge crystals and suspended continuous layers on Si(001) substrates deeply patterned in high aspect-ratio pillars. The material deposition was carried out in a commercial reduced-pressure chemical vapor deposition reactor, thus extending the "vertical-heteroepitaxy" technique developed by using the peculiar low-energy plasma-enhanced chemical vapor deposition reactor, to widely available epitaxial tools. The growth process was thoroughly analyzed, from the formation of small initial seeds to the final coalescence into a continuous suspended layer, by means of scanning and transmission electron microscopy, X-ray diffraction, and μ-Raman spectroscopy. The preoxidation of the Si pillar sidewalls and the addition of hydrochloric gas in the reactants proved to be key to achieve highly selective Ge growth on the pillars top only, which, in turn, is needed to promote the formation of a continuous Ge layer. Thanks to continuum growth models, we were able to single out the different roles played by thermodynamics and kinetics in the deposition dynamics. We believe that our findings will open the way to the low-cost realization of tens of micrometers thick heteroepitaxial layer (e.g., Ge, SiC, and GaAs) on Si having high crystal quality.

Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

NASA Technical Reports Server (NTRS)

Choi, Sang; King, Glen; Park, Yeonjoon

2009-01-01

SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations. This innovation utilizes newly developed rhombohedral epitaxy of cubic semiconductors on trigonal substrates in order to solve the lattice mismatch problem of SiGe by using trigonal single crystals like sapphire (Al2O3) as substrate to give a unique growth-orientation to the SiGe layer, which is automatically controlled at the interface upon sapphire (0001). This technology is different from previous silicon on insulator (SOI) or SGOI (SiGe on insulator) technologies that use amorphous SiO2 as the growth plane. A cubic semiconductor crystal is a special case of a rhombohedron with the inter-planar angle, alpha = 90 deg. With a mathematical transformation, all rhombohedrons can be described by trigonal crystal lattice structures. Therefore, all cubic lattice constants and crystal planes (hkl) s can be transformed into those of trigonal crystal parameters. These unique alignments enable a new opportunity of perfect lattice matching conditions, which can eliminate misfit dislocations. Previously, these atomic alignments were thought to be impossible or very difficult. With the invention of a new x-ray diffraction measurement method here, growth of cubic semiconductors on trigonal crystals became possible. This epitaxy and lattice-matching condition can be applied not only to SiGe (111)/sapphire (0001) substrate relations, but also to other crystal structures and other materials, including similar crystal structures which have pointgroup rotational symmetries by 120 because the cubic (111) direction has 120 rotational symmetry. The use of slightly miscut (less than plus or minus 10 deg.) sapphire (0001) substrate can be used to improve epitaxial relationships better by providing attractive atomic steps in the epitaxial process.

Photo-sensitive Ge nanocrystal based films controlled by substrate deposition temperature

NASA Astrophysics Data System (ADS)

Stavarache, Ionel; Maraloiu, Valentin Adrian; Negrila, Catalin; Prepelita, Petronela; Gruia, Ion; Iordache, Gheorghe

2017-10-01

Lowering the temperature of crystallization by deposition of thin films on a heated substrate represents the easiest way to find new means to develop and improve new working devices based on nanocrystals embedded in thin films. The improvements are strongly related with the increasing of operation speed, substantially decreasing the energy consumption and reducing unit fabrication costs of the respective semiconductor devices. This approach avoids major problems, such as those related to diffusion or difficulties in controlling nanocrystallites size, which appear during thermal treatments at high temperatures after deposition. This article reports on a significant progress given by structuring Ge nanocrystals (Ge-NCs) embedded in silicon dioxide (SiO2) thin films by heating the substrate at 400 °C during co-deposition of Ge and SiO2 by magnetron sputtering. As a proof-of-concept, a Si/Ge-NCs:SiO2 photo-sensitive structure was fabricated thereof and characterized. The structure shows superior performance on broad operation bandwidth from visible to near-infrared, as strong rectification properties in dark, significant current rise in the inversion mode when illuminated, high responsivity, high photo-detectivity of 1014 Jones, quick response and significant conversion efficiency with peak value reaching 850% at -1 V and about 1000 nm. This simple preparation approach brings an important contribution to the effort of structuring Ge nanocrystallites in SiO2 thin films at a lower temperature for the purpose of using these materials for devices in optoelectronics, solar cells and electronics on flexible substrates.

GaAs Solar Cells Grown on Unpolished, Spalled Ge Substrates: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cavalli, Alessandro; Johnston, Steven; Sulas, Dana

Decreasing the cost of single-crystal substrates by wafer reuse techniques has long been sought for III-V solar cells. Controlled spalling of III-V devices is a possible pathway for epitaxial liftoff, which would help reduce costs, but chemo- mechanical polishing after liftoff tends to limit the potential cost savings. Growth on an unpolished spalled surface would be an additional step toward lower costs, but it is crucial to show high efficiency solar cell devices on these unprocessed substrates. In this study, we spalled 2-inch Ge wafers using a Ni stressor layer, and then grew GaAs solar cells by HVPE on themore » spalled Ge surface without any other surface treatment. We show a 12.8% efficient single-junction device, without anti-reflection coating, with quantum efficiency very close to identical devices grown by HVPE on non-spalled GaAs substrates. Demonstrating a high carrier collection on unpolished spalled wafers is a step toward reducing substrate-related liftoff and reuse costs.« less

Development of Si(1-x)Ge(x) technology for microwave sensing applications

NASA Technical Reports Server (NTRS)

Mena, Rafael A.; Taub, Susan R.; Alterovitz, Samuel A.; Young, Paul E.; Simons, Rainee N.; Rosenfeld, David

1993-01-01

The progress for the first year of the work done under the Director's Discretionary Fund (DDF) research project entitled, 'Development of Si(1-x)Ge(x) Technology for Microwave Sensing Applications.' This project includes basic material characterization studies of silicon-germanium (SiGe), device processing on both silicon (Si) and SiGe substrates, and microwave characterization of transmission lines on silicon substrates. The material characterization studies consisted of ellipsometric and magneto-transport measurements and theoretical calculations of the SiGe band-structure. The device fabrication efforts consisted of establishing SiGe device processing capabilities in the Lewis cleanroom. The characterization of microwave transmission lines included studying the losses of various coplanar transmission lines and the development of transitions on silicon. Each part of the project is discussed individually and the findings for each part are presented. Future directions are also discussed.

Low-temperature formation of crystalline Si:H/Ge:H heterostructures by plasma-enhanced CVD in combination with Ni-nanodots seeding nucleation

NASA Astrophysics Data System (ADS)

Lu, Yimin; Makihara, Katsunori; Takeuchi, Daichi; Ikeda, Mitsuhisa; Ohta, Akio; Miyazaki, Seiichi

2017-06-01

Hydrogenated microcrystalline (µc) Si/Ge heterostructures were prepared on quartz substrates by plasma-enhanced chemical vapor deposition (CVD) from VHF inductively coupled plasma of SiH4 just after GeH4 employing Ni nanodots (NDs) as seeds for crystalline nucleation. The crystallinity of the films and the progress of grain growth were characterized by Raman scattering spectroscopy and atomic force microscopy (AFM), respectively. When the Ge films were grown on Ni-NDs at 250 °C, the growth of µc-Ge films with crystallinity as high as 80% was realized without an amorphous phase near the Ge film/quartz substrate interface. After the subsequent Si film deposition at 250 °C, fine grains were formed in the early stages of film growth on µc-Ge films with compositional mixing (µc-Si0.85Ge0.15:H) caused by the release of large lattice mismatch between c-Si and c-Ge. With further increase in Si:H film thickness, the formation of large grain structures accompanied by fine grains was promoted. These results suggest that crystalline Si/Ge heterojunctions can be used for efficient carrier collection in solar cell application.

Strong room temperature electroluminescence from lateral p-SiGe/i-Ge/n-SiGe heterojunction diodes on silicon-on-insulator substrate

NASA Astrophysics Data System (ADS)

Lin, Guangyang; Yi, Xiaohui; Li, Cheng; Chen, Ningli; Zhang, Lu; Chen, Songyan; Huang, Wei; Wang, Jianyuan; Xiong, Xihuan; Sun, Jiaming

2016-10-01

A lateral p-Si0.05Ge0.95/i-Ge/n-Si0.05Ge0.95 heterojunction light emitting diode on a silicon-on-insulator (SOI) substrate was proposed, which is profitable to achieve higher luminous extraction compared to vertical junctions. Due to the high carrier injection ratio of heterostructures and optical reflection at the SiO2/Si interface of the SOI, strong room temperature electroluminescence (EL) at around 1600 nm from the direct bandgap of i-Ge with 0.30% tensile strain was observed. The EL peak intensity of the lateral heterojunction is enhanced by ˜4 folds with a larger peak energy than that of the vertical Ge p-i-n homojunction, suggesting that the light emitting efficiency of the lateral heterojunction is effectively improved. The EL peak intensity of the lateral heterojunction, which increases quadratically with injection current density, becomes stronger for diodes with a wider i-Ge region. The CMOS compatible fabrication process of the lateral heterojunctions paves the way for the integration of the light source with the Ge metal-oxide-semiconductor field-effect-transistor.

Enzymatic degradation of lignin-carbohydrate complexes (LCCs): model studies using a fungal glucuronoyl esterase from Cerrena unicolor.

PubMed

d'Errico, Clotilde; Jørgensen, Jonas O; Krogh, Kristian B R M; Spodsberg, Nikolaj; Madsen, Robert; Monrad, Rune Nygaard

2015-05-01

Lignin-carbohydrate complexes (LCCs) are believed to influence the recalcitrance of lignocellulosic plant material preventing optimal utilization of biomass in e.g. forestry, feed and biofuel applications. The recently emerged carbohydrate esterase (CE) 15 family of glucuronoyl esterases (GEs) has been proposed to degrade ester LCC bonds between glucuronic acids in xylans and lignin alcohols thereby potentially improving delignification of lignocellulosic biomass when applied in conjunction with other cellulases, hemicellulases and oxidoreductases. Herein, we report the synthesis of four new GE model substrates comprising α- and ɣ-arylalkyl esters representative of the lignin part of naturally occurring ester LCCs as well as the cloning and purification of a novel GE from Cerrena unicolor (CuGE). Together with a known GE from Schizophyllum commune (ScGE), CuGE was biochemically characterized by means of Michaelis-Menten kinetics with respect to substrate specificity using the synthesized compounds. For both enzymes, a strong preference for 4-O-methyl glucuronoyl esters rather than unsubstituted glucuronoyl esters was observed. Moreover, we found that α-arylalkyl esters of methyl α-D-glucuronic acid are more easily cleaved by GEs than their corresponding ɣ-arylalkyl esters. Furthermore, our results suggest a preference of CuGE for glucuronoyl esters of bulky alcohols supporting the suggested biological action of GEs on LCCs. The synthesis of relevant GE model substrates presented here may provide a valuable tool for the screening, selection and development of industrially relevant GEs for delignification of biomass. © 2014 Wiley Periodicals, Inc.

van der Waals epitaxy of Ge films on mica

NASA Astrophysics Data System (ADS)

Littlejohn, A. J.; Xiang, Y.; Rauch, E.; Lu, T.-M.; Wang, G.-C.

2017-11-01

To date, many materials have been successfully grown on substrates through van der Waals epitaxy without adhering to the constraint of lattice matching as is required for traditional chemical epitaxy. However, for elemental semiconductors such as Ge, this has been challenging and therefore it has not been achieved thus far. In this paper, we report the observation of Ge epitaxially grown on mica at a narrow substrate temperature range around 425 °C. Despite the large lattice mismatch (23%) and the lack of high in-plane symmetry in the mica surface, an epitaxial Ge film with [111] out-of-plane orientation is observed. Crystallinity and electrical properties degrade upon deviation from the ideal growth temperature, as shown by Raman spectroscopy, X-ray diffraction, and Hall effect measurements. X-ray pole figure analysis reveals that there exist multiple rotational domains in the epitaxial Ge film with dominant in-plane orientations between Ge [" separators="|1 ¯10 ] and mica[100] of (20 n )°, where n = 0, 1, 2, 3, 4, 5. A superlattice area mismatch model was used to account for the likelihood of the in-plane orientation formation and was found to be qualitatively consistent with the observed dominant orientations. Our observation of Ge epitaxy with one out-of-plane growth direction through van der Waals forces is a step toward the growth of single crystal Ge films without the constraint in the lattice and symmetry matches with the substrates.

Investigation of structural and electrical properties on substrate material for high frequency metal-oxide-semiconductor (MOS) devices

NASA Astrophysics Data System (ADS)

Kumar, M.; Yang, Sung-Hyun; Janardhan Reddy, K.; JagadeeshChandra, S. V.

2017-04-01

Hafnium oxide (HfO2) thin films were grown on cleaned P-type <1 0 0> Ge and Si substrates by using atomic layer deposition technique (ALD) with thickness of 8 nm. The composition analysis of as-deposited and annealed HfO2 films was characterized by XPS, further electrical measurements; we fabricated the metal-oxide-semiconductor (MOS) devices with Pt electrode. Post deposition annealing in O2 ambient at 500 °C for 30 min was carried out on both Ge and Si devices. Capacitance-voltage (C-V) and conductance-voltage (G-V) curves measured at 1 MHz. The Ge MOS devices showed improved interfacial and electrical properties, high dielectric constant (~19), smaller EOT value (0.7 nm), and smaller D it value as Si MOS devices. The C-V curves shown significantly high accumulation capacitance values from Ge devices, relatively when compare with the Si MOS devices before and after annealing. It could be due to the presence of very thin interfacial layer at HfO2/Ge stacks than HfO2/Si stacks conformed by the HRTEM images. Besides, from current-voltage (I-V) curves of the Ge devices exhibited similar leakage current as Si devices. Therefore, Ge might be a reliable substrate material for structural, electrical and high frequency applications.

Flexible radio-frequency single-crystal germanium switch on plastic substrates

NASA Astrophysics Data System (ADS)

Qin, Guoxuan; Cai, Tianhao; Yuan, Hao-Chih; Seo, Jung-Hun; Ma, Jianguo; Ma, Zhenqiang

2014-04-01

This Letter presents the realization and characterizations of the flexible radio-frequency (RF)/microwave switches on plastic substrates employing single-crystal germanium (Ge) nanomembranes. The fabricated flexible Ge single-pole, single-throw (SPST) switches display high frequency responses (e.g., insertion loss of <1.3 dB at up to 30 GHz and isolation >10 dB at up to ˜13 GHz). RF performance tradeoff exists for the flexible Ge switches and the major affecting parameters are determined. The flexible Ge SPST switch shows better RF property to that of the flexible Si SPST switch. Underlying mechanism is investigated by theoretical analysis and modeling of switches with different structures.

Photonic metasurface made of array of lens-like SiGe Mie resonators formed on (100) Si substrate via dewetting

NASA Astrophysics Data System (ADS)

Poborchii, Vladimir; Shklyaev, Alexander; Bolotov, Leonid; Uchida, Noriyuki; Tada, Tetsuya; Utegulov, Zhandos N.

2017-12-01

Metasurfaces consisting of arrays of high-index Mie resonators concentrating/redirecting light are important for integrated optics, photodetectors, and solar cells. Herein, we report the optical properties of low-Ge-content SiGe lens-like Mie resonator island arrays fabricated via dewetting during Ge deposition on a Si(100) surface at approximately 900 °C. We observe enhancement of the Si interaction with light owing to the efficient island-induced light concentration in the submicron-depth Si layer, which is mediated by both near-field Mie resonance leaking into the substrate and far-field light focusing. Such metasurfaces can improve the Si photodetector and solar-cell performance.

Temperature dependence of the interband critical points of bulk Ge and strained Ge on Si

NASA Astrophysics Data System (ADS)

Fernando, Nalin S.; Nunley, T. Nathan; Ghosh, Ayana; Nelson, Cayla M.; Cooke, Jacqueline A.; Medina, Amber A.; Zollner, Stefan; Xu, Chi; Menendez, Jose; Kouvetakis, John

2017-11-01

Epitaxial Ge layers on a Si substrate experience a tensile biaxial stress due to the difference between the thermal expansion coefficients of the Ge epilayer and the Si substrate, which can be measured using asymmetric X-ray diffraction reciprocal space maps. This stress depends on temperature and affects the band structure, interband critical points, and optical spectra. This manuscripts reports careful measurements of the temperature dependence of the dielectric function and the interband critical point parameters of bulk Ge and Ge epilayers on Si using spectroscopic ellipsometry from 80 to 780 K and from 0.8 to 6.5 eV. The authors find a temperature-dependent redshift of the E1 and E1 + Δ1 critical points in Ge on Si (relative to bulk Ge). This redshift can be described well with a model based on thermal expansion coefficients, continuum elasticity theory, and the deformation potential theory for interband transitions. The interband transitions leading to E0‧ and E2 critical points have lower symmetry and therefore are not affected by the stress.

Study of low dimensional SiGe island on Si for potential visible Metal-Semiconductor-Metal photodetector

NASA Astrophysics Data System (ADS)

Rahim, Alhan Farhanah Abd; Zainal Badri, Nur'Amirah; Radzali, Rosfariza; Mahmood, Ainorkhilah

2017-11-01

In this paper, an investigation of design and simulation of silicon germanium (SiGe) islands on silicon (Si) was presented for potential visible metal semiconductor metal (MSM) photodetector. The characterization of the performances in term of the structural, optical and electrical properties of the structures was analyzed from the simulation results. The project involves simulation using SILVACO Technology Computer Aided Design (TCAD) tools. The different structures of the silicon germanium (SiGe) island on silicon substrate were created, which were large SiGe, small SiGe, combination SiGe and bulk Ge. All the structures were tested for potential Metal Semiconductor Metal (MSM) photodetector. The extracted data such as current versus voltage characteristic, current gain and spectral response were obtained using ATLAS SILVACO tools. The performance of SiGe island structures and bulk Ge on Si substrate as (MSM) photodetector was evaluated by photo and dark current-voltage (I-V) characteristics. It was found that SiGe islands exhibited higher energy band gap compared to bulk Ge. The SiGe islands current-voltage characteristics showed improved current gain compared to bulk Ge. Specifically the enhancement of the islands gain was contributed by the enhanced photo currents and lower dark currents. The spectral responses of the SiGe islands showed peak response at 590 nm (yellow) which is at the visible wavelength. This shows the feasibility of the SiGe islands to be utilized for visible photodetections.

Ion beam modification of structural and optical properties of GeO2 thin films deposited at various substrate temperatures using pulsed laser deposition

NASA Astrophysics Data System (ADS)

Rathore, Mahendra Singh; Vinod, Arun; Angalakurthi, Rambabu; Pathak, A. P.; Singh, Fouran; Thatikonda, Santhosh Kumar; Nelamarri, Srinivasa Rao

2017-11-01

High energy heavy ion irradiation-induced modification of high quality crystalline GeO2 thin films grown at different substrate temperatures ranging from 100 to 500 °C using pulsed laser deposition has been investigated. The pristine films were irradiated with 100 MeV Ag7+ ions at fixed fluence of 1 × 1013 ions/cm2. These pristine and irradiated films have been characterized using X-ray diffraction, atomic force microscopy, Raman spectroscopy, Fourier transform infrared and photoluminescence spectroscopy. The XRD and Raman results of pristine films confirm the formation of hexagonal structure of GeO2 films, whereas the irradiation eliminates all the peaks except major GeO2 peak of (101) plane. It is evident from the XRD results that crystallite size changes with substrate temperature and SHI irradiation. The surface morphology of films was studied by AFM. The functional group of pristine and irradiated films was investigated by IR transmission spectra. Pristine films exhibited strong photoluminescence around 342 and 470 nm due to oxygen defects and a red shift in the PL bands is observed after irradiation. Possible mechanism of tuning structural and optical properties of pristine as well as irradiated GeO2 films with substrate temperature and ion beam irradiation has been reported in detail.

The role of SiGe buffer in growth and relaxation of Ge on free-standing Si(001) nano-pillars.

PubMed

Zaumseil, P; Kozlowski, G; Schubert, M A; Yamamoto, Y; Bauer, J; Schülli, T U; Tillack, B; Schroeder, T

2012-09-07

We study the growth and relaxation processes of Ge nano-clusters selectively grown by chemical vapor deposition on free-standing 90 nm wide Si(001) nano-pillars with a thin Si(0.23)Ge(0.77) buffer layer. We found that the dome-shaped SiGe layer with a height of about 28 nm as well as the Ge dot deposited on top of it partially relaxes, mainly by elastic lattice bending. The Si nano-pillar shows a clear compliance behavior-an elastic response of the substrate on the growing film-with the tensile strained top part of the pillar. Additional annealing at 800 °C leads to the generation of misfit dislocation and reduces the compliance effect significantly. This example demonstrates that despite the compressive strain generated due to the surrounding SiO(2) growth mask it is possible to realize an overall tensile strain in the Si nano-pillar and following a compliant substrate effect by using a SiGe buffer layer. We further show that the SiGe buffer is able to improve the structural quality of the Ge nano-dot.

Single Junction InGaP/GaAs Solar Cells Grown on Si Substrates using SiGe Buffer Layers

NASA Technical Reports Server (NTRS)

Ringel, S. A.; Carlin, J. A.; Andre, C. L.; Hudait, M. K.; Gonzalez, M.; Wilt, D. M.; Clark, E. B.; Jenkins, P.; Scheiman, D.; Allerman, A.

2002-01-01

Single junction InGaP/GaAs solar cells displaying high efficiency and record high open circuit voltage values have been grown by metalorganic chemical vapor deposition on Ge/graded SiGe/Si substrates. Open circuit voltages as high as 980 mV under AM0 conditions have been verified to result from a single GaAs junction, with no evidence of Ge-related sub-cell photoresponse. Current AM0 efficiencies of close to 16% have been measured for a large number of small area cells, whose performance is limited by non-fundamental current losses due to significant surface reflection resulting from greater than 10% front surface metal coverage and wafer handling during the growth sequence for these prototype cells. It is shown that at the material quality currently achieved for GaAs grown on Ge/SiGe/Si substrates, namely a 10 nanosecond minority carrier lifetime that results from complete elimination of anti-phase domains and maintaining a threading dislocation density of approximately 8 x 10(exp 5) per square centimeter, 19-20% AM0 single junction GaAs cells are imminent. Experiments show that the high performance is not degraded for larger area cells, with identical open circuit voltages and higher short circuit current (due to reduced front metal coverage) values being demonstrated, indicating that large area scaling is possible in the near term. Comparison to a simple model indicates that the voltage output of these GaAs on Si cells follows ideal behavior expected for lattice mismatched devices, demonstrating that unaccounted for defects and issues that have plagued other methods to epitaxially integrate III-V cells with Si are resolved using SiGe buffers and proper GaAs nucleation methods. These early results already show the enormous and realistic potential of the virtual SiGe substrate approach for generating high efficiency, lightweight and strong III-V solar cells.

Germanium films by polymer-assisted deposition

DOEpatents

Jia, Quanxi; Burrell, Anthony K.; Bauer, Eve; Ronning, Filip; McCleskey, Thomas Mark; Zou, Guifu

2013-01-15

Highly ordered Ge films are prepared directly on single crystal Si substrates by applying an aqueous coating solution having Ge-bound polymer onto the substrate and then heating in a hydrogen-containing atmosphere. A coating solution was prepared by mixing water, a germanium compound, ethylenediaminetetraacetic acid, and polyethyleneimine to form a first aqueous solution and then subjecting the first aqueous solution to ultrafiltration.

GaAs Photovoltaics on Polycrystalline Ge Substrates

NASA Technical Reports Server (NTRS)

Wilt, David M.; Pal, AnnaMaria T.; McNatt, Jeremiah S.; Wolford, David S.; Landis, Geoffrey A.; Smith, Mark A.; Scheiman, David; Jenkins, Phillip P.; McElroy Bruce

2007-01-01

High efficiency III-V multijunction solar cells deposited on metal foil or even polymer substrates can provide tremendous advantages in mass and stowage, particularly for planetary missions. As a first step towards that goal, poly-crystalline p/i/n GaAs solar cells are under development on polycrystalline Ge substrates. Organo Metallic Vapor Phase Epitaxy (OMVPE) parameters for pre-growth bake, nucleation and deposition have been examined. Single junction p/i/n GaAs photovoltaic devices, incorporating InGaP front and back window layers, have been grown and processed. Device performance has shown a dependence upon the thickness of a GaAs buffer layer deposited between the Ge substrate and the active device structure. A thick (2 m) GaAs buffer provides for both increased average device performance as well as reduced sensitivity to variations in grain size and orientation. Illumination under IR light (lambda > 1 micron), the cells showed a Voc, demonstrating the presence of an unintended photoactive junction at the GaAs/Ge interface. The presence of this junction limited the efficiency to approx.13% (estimated with an anti-refection coating) due to the current mismatch and lack of tunnel junction interconnect.

Unusual island formations of Ir on Ge (111) studied by STM

NASA Astrophysics Data System (ADS)

van Zijll, M.; Huffman, E.; Lovinger, D. J.; Chiang, S.

2017-12-01

Island formation on the Ir/Ge(111) surface is studied using ultrahigh vacuum scanning tunneling microscopy. Ir was deposited at room temperature onto a Ge (111) substrate with coverages between 0.5 and 2.0 monolayers (ML). The samples were annealed to temperatures between 550 and 800 K, and then cooled prior to imaging. With 1.0 ML Ir coverage, at annealing temperatures 650-750 K, round islands form at locations where domain boundaries of the substrate reconstruction intersect. Both the substrate and the islands display a (√{ 3} x√{ 3}) R30∘ reconstruction. Additionally, a novel surface formation is observed where the Ir gathers along the antiphase domain boundaries between competing surface domains of the Ge surface reconstruction. This gives the appearance of the Ir in the domain boundaries forming pathways between different islands. The islands formed at higher annealing temperatures resulted in larger island sizes, which is evidence of Ostwald ripening. We present a model for the islands and the pathways which is consistent with our observations.

Nanogrids and Beehive-Like Nanostructures Formed by Plasma Etching the Self-Organized SiGe Islands

NASA Astrophysics Data System (ADS)

Chang, Yuan-Ming; Jian, Sheng-Rui; Juang, Jenh-Yih

2010-09-01

A lithography-free method for fabricating the nanogrids and quasi-beehive nanostructures on Si substrates is developed. It combines sequential treatments of thermal annealing with reactive ion etching (RIE) on SiGe thin films grown on (100)-Si substrates. The SiGe thin films deposited by ultrahigh vacuum chemical vapor deposition form self-assembled nanoislands via the strain-induced surface roughening (Asaro-Tiller-Grinfeld instability) during thermal annealing, which, in turn, serve as patterned sacrifice regions for subsequent RIE process carried out for fabricating nanogrids and beehive-like nanostructures on Si substrates. The scanning electron microscopy and atomic force microscopy observations confirmed that the resultant pattern of the obtained structures can be manipulated by tuning the treatment conditions, suggesting an interesting alternative route of producing self-organized nanostructures.

Effect of n-type doping level on direct band gap electroluminescence intensity for asymmetric metal/Ge/metal diodes

NASA Astrophysics Data System (ADS)

Maekura, T.; Tanaka, K.; Motoyama, C.; Yoneda, R.; Yamamoto, K.; Nakashima, H.; Wang, D.

2017-10-01

The direct band gap electroluminescence (EL) intensity was investigated for asymmetric metal/Ge/metal diodes fabricated on n-type Ge with doping levels in the range of 4.0 × 1013-3.1 × 1018 cm-3. Up to a doping level of 1016 cm-3 order, commercially available (100) n-Ge substrates were used. To obtain a doping level higher than 1017 cm-3 order, which is commercially unavailable, n+-Ge/p-Ge structures were fabricated by Sb doping on p-type (100) Ge substrates with an in-diffusion at 600 °C followed by a push-diffusion at 700 °C-850 °C. The EL intensity was increased with increasing doping level up to 1.0 × 1018 cm-3. After that, it was decreased with a further increase in n-type doping level. This EL intensity decrease is explained by the decreased number of holes in the active region. One reason is the difficulty in hole injection through the PtGe/n-Ge contact due to the occurring of tunneling electron current. Another reason is the loss of holes caused by both the small thickness of n+-Ge layer and the existence of n+p junction.

Heteroepitaxial Growth of Ferromagnetic MnSb(0001) Films on Ge/Si(111) Virtual Substrates.

PubMed

Burrows, Christopher W; Dobbie, Andrew; Myronov, Maksym; Hase, Thomas P A; Wilkins, Stuart B; Walker, Marc; Mudd, James J; Maskery, Ian; Lees, Martin R; McConville, Christopher F; Leadley, David R; Bell, Gavin R

2013-11-06

Molecular beam epitaxial growth of ferromagnetic MnSb(0001) has been achieved on high quality, fully relaxed Ge(111)/Si(111) virtual substrates grown by reduced pressure chemical vapor deposition. The epilayers were characterized using reflection high energy electron diffraction, synchrotron hard X-ray diffraction, X-ray photoemission spectroscopy, and magnetometry. The surface reconstructions, magnetic properties, crystalline quality, and strain relaxation behavior of the MnSb films are similar to those of MnSb grown on GaAs(111). In contrast to GaAs substrates, segregation of substrate atoms through the MnSb film does not occur, and alternative polymorphs of MnSb are absent.

Ge auto-doping and out-diffusion in InGaP grown on Ge substrate and their effects on the ordering of InGaP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Hong-Ming; Ho, Hao-I; Tsai, Shi-Jane

2016-03-21

We report on the Ge auto-doping and out-diffusion in InGaP epilayer with Cu-Pt ordering grown on 4-in. Ge substrate. Ge profiles determined from secondary ion mass spectrometry indicate that the Ge out-diffusion depth is within 100 nm. However, the edge of the wafer suffers from stronger Ge gas-phase auto-doping than the center, leading to ordering deterioration in the InGaP epilayer. In the edge, we observed a residual Cu-Pt ordering layer left beneath the surface, suggesting that the ordering deterioration takes place after the deposition rather than during the deposition and In/Ga inter-diffusion enhanced by Ge vapor-phase auto-doping is responsible for themore » deterioration. We thus propose a di-vacancy diffusion model, in which the amphoteric Ge increases the di-vacancy density, resulting in a Ge density dependent diffusion. In the model, the In/Ga inter-diffusion and Ge out-diffusion are realized by the random hopping of In/Ga host atoms and Ge atoms to di-vacancies, respectively. Simulation based on this model well fits the Ge out-diffusion profiles, suggesting its validity. By comparing the Ge diffusion coefficient obtained from the fitting and the characteristic time constant of ordering deterioration estimated from the residual ordering layer, we found that the hopping rates of Ge and the host atoms are in the same order of magnitude, indicating that di-vacancies are bound in the vicinity of Ge atoms.« less

Interfacial kinetics in nanosized Au/Ge films: An in situ TEM study

NASA Astrophysics Data System (ADS)

Kryshtal, Aleksandr P.; Minenkov, Alexey A.; Ferreira, Paulo J.

2017-07-01

We investigate the morphology and crystalline structure of Au/Ge films in a wide range of temperatures by in situ TEM heating. Au/Ge films with Au mass thickness of 0.2-0.3 nm and Ge thickness of 5 nm were produced in vacuum by the sequential deposition of components on a carbon substrate at room temperature. It has been shown that particles with an average size of 4 nm, formed by Au film de-wetting, melt on the germanium substrate at temperatures 110-160 °C, which are below the eutectic temperature for the bulk. The effect of crystallization-induced capillary motion of liquid eutectic particles over Ge surface has been found in this work. Formation of metastable fcc phase of Ge has been observed at the liquid-germanium interface and behind the moving particle. Formation of a liquid phase with its subsequent crystallization at the metal-semiconductor interface seems to play a key role in the metal-induced crystallization effect.

Comparative Study of HfTa-based gate-dielectric Ge metal-oxide-semiconductor capacitors with and without AlON interlayer

NASA Astrophysics Data System (ADS)

Xu, J. P.; Zhang, X. F.; Li, C. X.; Chan, C. L.; Lai, P. T.

2010-04-01

The electrical properties and high-field reliability of HfTa-based gate-dielectric metal-oxide-semiconductor (MOS) devices with and without AlON interlayer on Ge substrate are investigated. Experimental results show that the MOS capacitor with HfTaON/AlON stack gate dielectric exhibits low interface-state/oxide-charge densities, low gate leakage, small capacitance equivalent thickness (˜1.1 nm), and high dielectric constant (˜20). All of these should be attributed to the blocking role of the ultrathin AlON interlayer against interdiffusions of Ge, Hf, and Ta and penetration of O into the Ge substrate, with the latter effectively suppressing the unintentional formation of unstable poor-quality low- k GeO x and giving a superior AlON/Ge interface. Moreover, incorporation of N into both the interlayer and high- k dielectric further improves the device reliability under high-field stress through the formation of strong N-related bonds.

Investigation of Room temperature Ferromagnetism in Mn doped Ge

NASA Astrophysics Data System (ADS)

Colakerol Arslan, Leyla; Toydemir, Burcu; Onel, Aykut Can; Ertas, Merve; Doganay, Hatice; Gebze Inst of Tech Collaboration; Research Center Julich Collaboration

2014-03-01

We present a systematic investigation of structural, magnetic and electronic properties of MnxGe1 -x single crystals. MnxGe1-x films were grown by sequential deposition of Ge and Mn by molecular-beam epitaxy at low substrate temperatures in order to avoid precipitation of ferromagnetic Ge-Mn intermetallic compounds. Reflected high energy electron diffraction and x-ray diffraction observations revealed that films are epitaxially grown on Si (001) substrates from the initial stage without any other phase formation. Magnetic measurements carried out using a physical property measurement system showed that all samples exhibited ferromagnetism at room temperature. Electron spin resonance indicates the presence of magnetically ordered localized spins of divalent Mn ions. X-ray absorption measurements at the Mn L-edge confirm significant substitutional doping of Mn into Ge-sites. The ferromagnetism was mainly induced by Mn substitution for Ge site, and indirect exchange interaction of these magnetic ions with the intrinsic charge carriers is the origin of ferromagnetism. The magnetic interactions were better understood by codoping with nonmagnetic impurities. This work was supported by Marie-Curie Reintegration Grant (PIRG08-GA-2010-276973).

Structural, optical, and spin properties of hydrogenated amorphous silicon-germanium alloys

NASA Astrophysics Data System (ADS)

Stutzmann, M.; Street, R. A.; Tsai, C. C.; Boyce, J. B.; Ready, S. E.

1989-07-01

We report on a detailed study of structural and electronic properties of hydrogenated amorphous silicon-germanium alloys deposited by rf glow discharge from SiH4 and GeH4 in a diode reactor. The chemical composition of the alloys is related to the deposition conditions, with special emphasis on preferential incorporation of Ge into the solid phase and on the role of inert dilutant gases. Hydrogen bonding in the alloys is investigated with nuclear magnetic resonance and vibrational (Raman and infrared) spectroscopy. The optical properties of a-SiGe:H samples deposited under optimal conditions are analyzed with the help of subgap absorption measurements and band-tail luminescence for the entire range of alloy composi-tions. A large part of the article describes an investigation of the electron-spin-resonance response of undoped alloys. The spin density associated with dangling bond defects localized on Si and Ge atoms has been measured as a function of alloy composition for optimized material. In addition, the dependence of the two defect densities on the detailed deposition conditions (rf power, substrate temperature, and dilution) has been determined in a systematic way for alloys deposited from a plasma with a fixed SiH4/GeH4ratio. The results of this study, especially the preferential creation of Ge dangling bonds, are discussed in the context of our structural data. Furthermore, spin resonance is employed to investigate the light-induced degradation (Staebler-Wronski effect) of a-SiGe:H. Finally, the changes of the spin-resonance spectra of a-Si0.7 Ge0.3 :H upon substitutional doping with phosphorus and boron have been obtained experimentally, and are used to construct a model for the electronic density of states in this material.

High-resolution electron microscope observation of voids in amorphous Ge.

NASA Technical Reports Server (NTRS)

Donovan, T. M.; Heinemann, K.

1971-01-01

Electron micrographs have been obtained which clearly show the existence of a void network in amorphous Ge films formed at substrate temperatures of 25 and 150 C, and the absence of a void network in films formed at higher substrate temperatures of 200 and 250 C. These results correlate quite well with density measurements and predictions of void densities by indirect methods.

Large-area ordered Ge-Si compound quantum dot molecules on dot-patterned Si (001) substrates

NASA Astrophysics Data System (ADS)

Lei, Hui; Zhou, Tong; Wang, Shuguang; Fan, Yongliang; Zhong, Zhenyang

2014-08-01

We report on the formation of large-area ordered Ge-Si compound quantum dot molecules (CQDMs) in a combination of nanosphere lithography and self-assembly. Truncated-pyramid-like Si dots with {11n} facets are readily formed, which are spatially ordered in a large area with controlled period and size. Each Si dot induces four self-assembled Ge-rich dots at its base edges that can be fourfold symmetric along <110> directions. A model based on surface chemical potential accounts well for these phenomena. Our results disclose the critical effect of surface curvature on the diffusion and the aggregation of Ge adatoms and shed new light on the unique features and the inherent mechanism of self-assembled QDs on patterned substrates. Such a configuration of one Si QD surrounded by fourfold symmetric Ge-rich QDs can be seen as a CQDM with unique features, which will have potential applications in novel devices.

Improved interfacial and electrical properties of atomic layer deposition HfO2 films on Ge with La2O3 passivation

NASA Astrophysics Data System (ADS)

Li, Xue-Fei; Liu, Xiao-Jie; Cao, Yan-Qiang; Li, Ai-Dong; Li, Hui; Wu, Di

2013-01-01

We report the characteristics of HfO2 films deposited on Ge substrates with and without La2O3 passivation at 250 °C by atomic layer deposition (ALD) using La[N(SiMe3)2]3 and Hf[N(CH3)(C2H5)]4 as the precursors. The HfO2 is observed to form defective HfGeOx at its interface during 500 °C postdeposition annealing. The insertion of an ultrathin La2O3 interfacial passivation layer effectively prevents the Ge outdiffusion and improves interfacial and electrical properties. Capacitance equivalent thickness (CET) of 1.35 nm with leakage current density JA of 8.3 × 10-4 A/cm2 at Vg = 1 V is achieved for the HfO2/La2O3 gate stacks on Ge substrates.

Effect of substrate baking temperature on zinc sulfide and germanium thin films optical parameters

NASA Astrophysics Data System (ADS)

Liu, Fang; Gao, Jiaobo; Yang, Chongmin; Zhang, Jianfu; Liu, Yongqiang; Liu, Qinglong; Wang, Songlin; Mi, Gaoyuan; Wang, Huina

2016-10-01

ZnS and Ge are very normal optical thin film materials in Infrared wave. Studying the influence of different substrate baking temperature to refractive index and actual deposition rates is very important to promote optical thin film quality. In the same vacuum level, monitoring thickness and evaporation rate, we use hot evaporation to deposit ZnS thin film materials and use ion-assisted electron beam to deposit Ge thin film materials with different baking temperature. We measure the spectral transmittance with the spectrophotometer and calculate the actual deposition rates and the refractive index in different temperature. With the higher and higher temperature in a particular range, ZnS and Ge refractive index become higher and actual deposition rates become smaller. The refractive index of Ge film material change with baking temperature is more sensitive than ZnS. However, ZnS film actual deposition rates change with baking temperature is more sensitive than Ge.

Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate

PubMed Central

Lin, Guangyang; Chen, Ningli; Zhang, Lu; Huang, Zhiwei; Huang, Wei; Wang, Jianyuan; Xu, Jianfang; Chen, Songyan; Li, Cheng

2016-01-01

Direct band electroluminescence (EL) from tensile-strained Si0.13Ge0.87/Ge multiple quantum wells (MQWs) on a Ge virtual substrate (VS) at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300–1400 nm and 1600–1700 nm, respectively. The peak energy of EL shifted to the lower energy side superquadratically with an increase of injection current density as a result of the Joule heating effect. During the elevation of environmental temperature, EL intensity increased due to a reduction of energy between L and Γ valleys of Ge. Empirical fitting of the relationship between the integrated intensity of EL (L) and injection current density (J) with L~Jm shows that the m factor increased with injection current density, suggesting higher light emitting efficiency of the diode at larger injection current densities, which can be attributed to larger carrier occupations in the Γ valley and the heavy hole (HH) valance band at higher temperatures. PMID:28773923

Room Temperature Electroluminescence from Tensile-Strained Si0.13Ge0.87/Ge Multiple Quantum Wells on a Ge Virtual Substrate.

PubMed

Lin, Guangyang; Chen, Ningli; Zhang, Lu; Huang, Zhiwei; Huang, Wei; Wang, Jianyuan; Xu, Jianfang; Chen, Songyan; Li, Cheng

2016-09-27

Direct band electroluminescence (EL) from tensile-strained Si 0.13 Ge 0.87 /Ge multiple quantum wells (MQWs) on a Ge virtual substrate (VS) at room temperature is reported herein. Due to the competitive result of quantum confinement Stark effect and bandgap narrowing induced by tensile strain in Ge wells, electroluminescence from Γ1-HH1 transition in 12-nm Ge wells was observed at around 1550 nm. As injection current density increases, additional emission shoulders from Γ2-HH2 transition in Ge wells and Ge VS appeared at around 1300-1400 nm and 1600-1700 nm, respectively. The peak energy of EL shifted to the lower energy side superquadratically with an increase of injection current density as a result of the Joule heating effect. During the elevation of environmental temperature, EL intensity increased due to a reduction of energy between L and Γ valleys of Ge. Empirical fitting of the relationship between the integrated intensity of EL ( L ) and injection current density ( J ) with L ~ J m shows that the m factor increased with injection current density, suggesting higher light emitting efficiency of the diode at larger injection current densities, which can be attributed to larger carrier occupations in the Γ valley and the heavy hole (HH) valance band at higher temperatures.

Characterization of SiGe/Ge heterostructures and graded layers using variable angle spectroscopic ellipsometry

NASA Technical Reports Server (NTRS)

Croke, E. T.; Wang, K. L.; Heyd, A. R.; Alterovitz, S. A.; Lee, C. H.

1996-01-01

Variable angle spectroscopic ellipsometry (VASE) has been used to characterize Si(x)Ge(1-x)/Ge superlattices (SLs) grown on Ge substrates and thick Si(x)Ge(1-x)/Ge heterostructures grown on Si substrates. Our VASE analysis yielded the thicknesses and alloy compositions of all layers within the optical penetration depth of the surface. In addition, strain effects were observed in the VASE results for layers under both compressive and tensile strain. Results for the SL structures were found to be in close agreement with high resolution x-ray diffraction measurements made on the same samples. The VASE analysis has been upgraded to characterize linearly graded Si(x)Ge(1-x) buffer layers. The algorithm has been used to determine the total thickness of the buffer layer along with the start and end alloy composition by breaking the total thickness into many (typically more than 20) equal layers. Our ellipsometric results for 1 (mu)m buffer layers graded in the ranges 0.7 less than or = x less than or = 1.0, and 0.5 less than or = x less than or = 1.0 are presented, and compare favorably with the nominal values.

Determination of the Wetting Angle of Germanium and Germanium-Silicon Melts on Different Substrate Materials

NASA Technical Reports Server (NTRS)

Kaiser, Natalie; Croell, Arne; Szofran, F. R.; Cobb. S. D.; Dold, P.; Benz, K. W.

1999-01-01

During Bridgman growth of semiconductors detachment of the crystal and the melt meniscus has occasionally been observed, mainly under microgravity (microg) conditions. An important factor for detached growth is the wetting angle of the melt with the crucible material. High contact angles are more likely to result in detachment of the growing crystal from the ampoule wall. In order to achieve detached growth of germanium (Ge) and germanium-silicon (GeSi) crystals under 1g and microg conditions, sessile drop measurements were performed to determine the most suitable ampoule material as well as temperature dependence of the surface tension for GeSi. Sapphire, fused quartz, glassy carbon, graphite, SiC, pyrolytic Boron Nitride (pBN), AIN, and diamond were used as substrates. Furthermore, different cleaning procedures and surface treatments (etching, sandblasting, etc.) of the same substrate material and their effect on the wetting behavior were studied during these experiments. pBN and AIN substrates exhibited the highest contact angles with values around 170 deg.

Growth of high quality germanium films on patterned silicon substrates and applications

NASA Astrophysics Data System (ADS)

Vanamu, Ganesh

The principal objective of this work is to determine optimal pattern structures for highest quality (defect free) heteroepitaxial growth. High quality films of Ge on Si are of significant importance and can be used in high electron mobility devices, photodetectors for optical communications (1.3mum or 1.55mum) and integrating III-V optoelectronic devices. However, a 4% lattice mismatch and ˜ 50% thermal expansion mismatch between Ge and Si create three major challenges in growing high quality Ge films on Si, (a) high surface roughness due to a pronounced <110> crosshatch pattern, (b) high dislocation densities in Ge films and (c) high density of microcracks and wafer bending. A common way of reducing lattice and thermal expansion mismatch is to form a "virtual substrate (VS)" by growing a graded composition followed by a uniform layer of the desired epitaxial film on a defect-free Si substrate. Virtual graded layers could not decrease the dislocation densities to the numbers acceptable for most of the devices. Mathews et al. first proposed that limiting the lateral dimensions of the sample prior to growth could reduce the dislocation density. Later On Fitzgerald proposed that patterning decreases the dislocation density in the films. In this work we show high quality crosshatch-free Ge films with dislocation density ˜ 105 cm-2 on the nano-patterned Si and also high quality GaAs films on the Ge/Si virtual substrate. The first step in this research was to perform a systematic study to identify the role of pattern width on the quality of Ge growth. We investigated micrometer and submicrometer scale patterns. We demonstrated that the quality of the heteroepitaxial layers improves as the pattern width decreases. Then we have decreased the pattern width to nanometer-scale dimensions. Significant improvement of the Ge film quality was observed. We used novel interferometric lithography techniques combined with reactive ion and wet chemical etching to fabricate Si structures. The patterning was done using standard photomask based lithography. We analyzed the quality of the Ge films using high resolution x-ray diffraction, TEM and SEM. We performed etch pit density (EPD) measurements by counting the pits formed using a Nomarski optical microscope. In order to correlate characterization with device performance, we designed an inter-digitated pattern to form Ge based metal semiconductor metal photodetector and measured the photoresponse of the Ge films. Preliminary results were very promising. We then grew 4 mum GaAs on the Ge/Si using MBE (0.5 mum/hr and 570°C) and analyzed the GaAs film quality. We also performed modeling to calculate strain energy density and wafer bending in multi-layer films grown epitaxially on planar Si substrates. We have also compared the models with experiments. (Abstract shortened by UMI.)

Ion-beam mixed ultra-thin cobalt suicide (CoSi2) films by cobalt sputtering and rapid thermal annealing

NASA Astrophysics Data System (ADS)

Kal, S.; Kasko, I.; Ryssel, H.

1995-10-01

The influence of ion-beam mixing on ultra-thin cobalt silicide (CoSi2) formation was investigated by characterizing the ion-beam mixed and unmixed CoSi2 films. A Ge+ ion-implantation through the Co film prior to silicidation causes an interface mixing of the cobalt film with the silicon substrate and results in improved silicide-to-silicon interface roughness. Rapid thermal annealing was used to form Ge+ ion mixed and unmixed thin CoSi2 layer from 10 nm sputter deposited Co film. The silicide films were characterized by secondary neutral mass spectroscopy, x-ray diffraction, tunneling electron microscopy (TEM), Rutherford backscattering, and sheet resistance measurements. The experi-mental results indicate that the final rapid thermal annealing temperature should not exceed 800°C for thin (<50 nm) CoSi2 preparation. A comparison of the plan-view and cross-section TEM micrographs of the ion-beam mixed and unmixed CoSi2 films reveals that Ge+ ion mixing (45 keV, 1 × 1015 cm-2) produces homogeneous silicide with smooth silicide-to-silicon interface.

Gastric emptying and orocaecal transit time of meals containing lactulose or inulin in men.

PubMed

Clegg, Miriam; Shafat, Amir

2010-08-01

The H(2) breath test is ideal for orocaecal transit time (OCTT) measurement, as it is non-invasive and inexpensive. Indigestible substrates added to a test meal are metabolised by the colonic bacteria, resulting in the production of H(2) which is detected in end-exhalation breath. However, the substrates themselves can alter the transit times in the gastrointestinal tract. The aim of the present study is to compare OCTT and gastric emptying (GE) when lactulose in liquid (L-L), solid lactulose (L-S) and solid inulin (IN-S) are added to a test meal, and subsequently, to examine if inulin alters GE. Firstly, ten male volunteers were tested on three occasions. Volunteers ate a pancake breakfast containing 100 mg of (13)C-octanoic acid and either 12 g of L-L, 12 g of L-S or 12 g of IN-S in a randomised order. Secondly, seven male volunteers were tested twice with meals containing either 12 g of IN-S or no substrate (NO-S). L-L induced the shortest OCTT (85.3 (sd 42.8) min) compared with L-S (162.4 (sd 62.6) min) and inulin (292.4 (sd 66.7) min; P = 0.007). GE half-time and lag phase (L-L: 61 (sd 9); L-S: 57 (sd 10); IN-S: 52 (sd 10) min; P = 0.005) were also affected, with L-L being the slowest. Thirdly, inulin reduced GE lag and latency phases (P < 0.05) compared with NO-S. Lactulose accelerates OCTT but delays GE compared with inulin. Inulin accelerates the onset of stomach emptying, but it has no effect on GE half-time. For these reasons, inulin is the preferred substrate for the H(2) breath test.

Progress toward thin-film GaAs solar cells using a single-crystal Si substrate with a Ge interlayer

NASA Technical Reports Server (NTRS)

Yeh, Y. C. M.; Wang, K. L.; Zwerdling, S.

1982-01-01

Development of a technology for fabricating light-weight, high-efficiency, radiation-resistant solar cells for space applications is reported. The approaches currently adopted are to fabricate shallow homojunction n(+)/p as well as p/n AlGaAs-heteroface GaAs solar cells by organometallic chemical vapor deposition (OM-CVD) on single-crystal Si substrates using in each case, a thin Ge epi-interlayer first grown by CVD. This approach maintains the advantages of the low specific gravity of Si as well as the high efficiency and radiation-resistant properties of the GaAs solar cell which can lead to greatly improved specific power for a solar array. The growth of single-crystal GaAs epilayers on Ge epi-interlayers on Si substrates is investigated. Related solar cell fabrication is reviewed.

Optoelectronic Characterization of Infrared Photodetector Fabricated on Ge-on-Si Substrate.

PubMed

Khurelbaatar, Zagarzusem; Kil, Yeon-Ho; Kim, Taek Sung; Shim, Kyu-Hwan; Hong, Hyobong; Choi, Chel-Jong

2015-10-01

We report on the optoelectronic characterization of Ge p-i-n infrared photodetector fabricated on Ge-on-Si substrate using rapid thermal chemical vapor deposition (RTCVD). The phosphorous doping concentration and the root mean square (RMS) surface roughness of epitaxial layer was estimated to be 2 x 10(18) cm(-3) and 1.2 nm, respectively. The photodetector were characterized with respect to their dark, photocurrent and responsivities in the wavelength range of 1530-1630 nm. At 1550 nm wavelength, responsivity of 0.32 A/W was measured for a reverse bias of 1 V, corresponding to 25% external quantum efficiency, without an optimal antireflection coating. Responsivity drastically reduced from 1560 nm wavelength which could be attributed to decreased absorption of Ge at room temperature.

Germanium Nanocrystal Solar Cells

NASA Astrophysics Data System (ADS)

Holman, Zachary Charles

Greenhouse gas concentrations in the atmosphere are approaching historically unprecedented levels from burning fossil fuels to meet the ever-increasing world energy demand. A rapid transition to clean energy sources is necessary to avoid the potentially catastrophic consequences of global warming. The sun provides more than enough energy to power the world, and solar cells that convert sunlight to electricity are commercially available. However, the high cost and low efficiency of current solar cells prevent their widespread implementation, and grid parity is not anticipated to be reached for at least 15 years without breakthrough technologies. Semiconductor nanocrystals (NCs) show promise for cheap multi-junction photovoltaic devices. To compete with photovoltaic materials that are currently commercially available, NCs need to be inexpensively cast into dense thin films with bulk-like electrical mobilities and absorption spectra that can be tuned by altering the NC size. The Group II-VI and IV-VI NC communities have had some success in achieving this goal by drying and then chemically treating colloidal particles, but the more abundant and less toxic Group IV NCs have proven more challenging. This thesis reports thin films of plasma-synthesized Ge NCs deposited using three different techniques, and preliminary solar cells based on these films. Germanium tetrachloride is dissociated in the presence of hydrogen in a nonthermal plasma to nucleate Ge NCs. Transmission electron microscopy and X-ray diffraction indicate that the particles are nearly monodisperse (standard deviations of 10-15% the mean particle diameter) and the mean diameter can be tuned from 4-15 nm by changing the residence time of the Ge NCs in the plasma. In the first deposition scheme, a Ge NC colloid is formed by reacting nanocrystalline powder with 1-dodecene and dispersing the functionalized NCs in a solvent. Films are then formed on substrates by drop-casting the colloid and allowing it to dry. As-deposited films are electrically insulating due to the long hydrocarbon molecules separating neighboring particles; however, mass spectrometry shows that annealing treatments successfully decompose these molecules. After annealing at 250 °C, Ge NC films exhibit conductivities as large as 10-6 S/cm. In the second film deposition scheme, a Ge NC colloid is formed by dispersing Ge NCs in select solvents without further surface modification. While these "bare" NCs quickly agglomerate and flocculate in nearly all non-polar solvents, they remain stable in benzonitrile and 1,2-dichlorobenzene, among others. Thin-film field-effect transistors have been fabricated by spinning Ge NC colloids onto substrates and the films have been subjected to various annealing procedures. The devices show n-type, p -type, or ambipolar behavior depending on the annealing conditions, with Ge NC films annealed at 300°C exhibiting electron saturation mobilities greater than 10-2 cm2/Vs and on-to-off ratios of 104. The final film deposition scheme involves the impaction of Ge NCs onto substrates downstream of the synthesis plasma via acceleration of the NCs through an orifice. This technique produces highly uniform films with densities greater than 50% of the density of bulk Ge. By varying the size of the Ge NCs, we have measured films with band gaps ranging from the bulk value of 0.7 eV to over 1.1 eV for films of 4 nm Ge NCs. Having deposited dense thin films with tunable band gaps and respectable mobilities, we have begun fabricating bilayer solar cells consisting of heterojunctions between Ge NC films and P3HT, Si NCs, or Si wafers. Preliminary devices exhibit opencircuit voltages and short-circuit currents as large as 0.3 V and 4 mA/cm 2, respectively.

Interfacial band alignment and structural properties of nanoscale TiO2 thin films for integration with epitaxial crystallographic oriented germanium

NASA Astrophysics Data System (ADS)

Jain, N.; Zhu, Y.; Maurya, D.; Varghese, R.; Priya, S.; Hudait, M. K.

2014-01-01

We have investigated the structural and band alignment properties of nanoscale titanium dioxide (TiO2) thin films deposited on epitaxial crystallographic oriented Ge layers grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy. The TiO2 thin films deposited at low temperature by physical vapor deposition were found to be amorphous in nature, and high-resolution transmission electron microscopy confirmed a sharp heterointerface between the TiO2 thin film and the epitaxially grown Ge with no traceable interfacial layer. A comprehensive assessment on the effect of substrate orientation on the band alignment at the TiO2/Ge heterointerface is presented by utilizing x-ray photoelectron spectroscopy and spectroscopic ellipsometry. A band-gap of 3.33 ± 0.02 eV was determined for the amorphous TiO2 thin film from the Tauc plot. Irrespective of the crystallographic orientation of the epitaxial Ge layer, a sufficient valence band-offset of greater than 2 eV was obtained at the TiO2/Ge heterointerface while the corresponding conduction band-offsets for the aforementioned TiO2/Ge system were found to be smaller than 1 eV. A comparative assessment on the effect of Ge substrate orientation revealed a valence band-offset relation of ΔEV(100) > ΔEV(111) > ΔEV(110) and a conduction band-offset relation of ΔEC(110) > ΔEC(111) > ΔEC(100). These band-offset parameters are of critical importance and will provide key insight for the design and performance analysis of TiO2 for potential high-κ dielectric integration and for future metal-insulator-semiconductor contact applications with next generation of Ge based metal-oxide field-effect transistors.

Material gain engineering in GeSn/Ge quantum wells integrated with an Si platform

NASA Astrophysics Data System (ADS)

Mączko, H. S.; Kudrawiec, R.; Gladysiewicz, M.

2016-09-01

It is shown that compressively strained Ge1-xSnx/Ge quantum wells (QWs) grown on a Ge substrate with 0.1 ≤ x ≤ 0.2 and width of 8 nm ≤ d ≤ 14 nm are a very promising gain medium for lasers integrated with an Si platform. Such QWs are type-I QWs with a direct bandgap and positive transverse electric mode of material gain, i.e. the modal gain. The electronic band structure near the center of Brillouin zone has been calculated for various Ge1-xSnx/Ge QWs with use of the 8-band kp Hamiltonian. To calculate the material gain for these QWs, occupation of the L valley in Ge barriers has been taken into account. It is clearly shown that this occupation has a lot of influence on the material gain in the QWs with low Sn concentrations (Sn < 15%) and is less important for QWs with larger Sn concentration (Sn > 15%). However, for QWs with Sn > 20% the critical thickness of a GeSn layer deposited on a Ge substrate starts to play an important role. Reduction in the QW width shifts up the ground electron subband in the QW and increases occupation of the L valley in the barriers instead of the Γ valley in the QW region.

The Au modified Ge(1 1 0) surface

NASA Astrophysics Data System (ADS)

Zhang, L.; Kabanov, N. S.; Bampoulis, P.; Saletsky, A. M.; Zandvliet, H. J. W.; Klavsyuk, A. L.

2018-05-01

The pristine Ge(1 1 0) surface is composed of Ge pentagons, which are arranged in relatively large (16 × 2) and c(8 × 10) unit cells. The deposition of sub-monolayer amounts of Au and mild annealing results into de-reconstructed Ge(1 1 0) regions completely free of Ge pentagons and regions composed of nanowires that are aligned along the high symmetry [ 1 1 bar 0 ] direction of the Ge(1 1 0) surface. The de-reconstructed Ge(1 1 0) regions consist of atomic rows that are aligned along the [ 1 1 bar 0 ] direction. A substantial fraction of these substrate rows are straight and resemble the atom rows of the unreconstructed, i.e. bulk terminated, Ge(1 1 0) surface, whereas the other substrate rows have a meandering appearance. These meandering atom rows are comprised of two types of atoms, one type that appears dim, whereas the other type appears bright in filled-state scanning tunneling microscopy images. Using density functional theory calculations, we have tested more than 20 different atomic models for the meandering atom rows. The density functional theory calculations reveal that it is energetically favorable for the deposited Au atoms to exchange position with Ge atoms in the first layer. Based on these findings we conclude that the bright atoms are Ge atoms, whereas the dim atoms are Au atoms.

Evaluation of GeO desorption behavior in the metalGeO(2)Ge structure and its improvement of the electrical characteristics.

PubMed

Oniki, Yusuke; Koumo, Hideo; Iwazaki, Yoshitaka; Ueno, Tomo

2010-06-15

The relation between germanium monoxide (GeO) desorption and either improvement or deterioration in electrical characteristics of metalGeO(2)Ge capacitors fabricated by thermal oxidation has been investigated. In the metalGeO(2)Ge stack, two processes of GeO desorption at different sites and at different temperatures were observed by thermal desorption spectroscopy measurements. The electrical characteristics of as-oxidized metalGeO(2)Ge capacitors shows a large flat-band voltage shift and minority carrier generation due to the GeO desorption from the GeO(2)Ge interface during oxidation of Ge substrates. On the other hand, the electrical properties were drastically improved by a postmetallization annealing at low temperature resulting in a metal catalyzed GeO desorption from the top interface.

Organometallic chemical vapor deposition and characterization of ZnGeP2/GaP multiple heterostructures on GaP substrates

NASA Technical Reports Server (NTRS)

Xing, G. C.; Bachmann, Klaus J.

1993-01-01

The growth of ZnGeP2/GaP double and multiple heterostructures on GaP substrates by organometallic chemical vapor deposition is reported. These epitaxial films were deposited at a temperature of 580 C using dimethylzinc, trimethylgallium, germane, and phosphine as source gases. With appropriate deposition conditions, mirror smooth epitaxial GaP/ZnGeP2 multiple heterostructures were obtained on (001) GaP substrates. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS) studies of the films showed that the interfaces are sharp and smooth. Etching study of the films showed dislocation density on the order of 5x10(exp 4)cm(sup -2). The growth rates of the GaP layers depend linearly on the flow rates of trimethylgallium. While the GaP layers crystallize in zinc-blende structure, the ZnGeP2 layers crystallize in the chalcopyrite structure as determined by (010) electron diffraction pattern. This is the first time that multiple heterostructures combining these two crystal structures were made.

Growth of Bi2Se3 topological insulator thin film on Ge(1 1 1) substrate

NASA Astrophysics Data System (ADS)

Kim, Seungyeon; Lee, Sangsoo; Woo, Jeongseok; Lee, Geunseop

2018-02-01

Atomically smooth, single crystalline Bi2Se3 thin films were grown on a Ge(1 1 1) substrate using molecular beam epitaxy. Crystallinities of both the surface and the bulk as well as the stoichiometry of the grown film were characterized by using low-energy electron diffraction, scanning tunneling microscopy, X-ray diffraction, and photoelectron spectroscopies. Hexagonal atomic structures, quintuple layer steps observed in STM images confirmed that the Bi2Se3 film with a (0 0 0 1) surface was grown. Diffraction peak positions as well as the chemical composition determined from the core-level photoelectron spectra coincide well with those expected for the Bi2Se3 crystal. The surface state with a Dirac cone was observed in the valence photoelectron spectra, which also support that a high-quality Bi2Se3 film was grown on the Ge(1 1 1) substrate. The interface between Ge(1 1 1) and Bi2Se3(0 0 0 1) is expected to be abrupt due to the small lattice between them.

Misfit dislocation gettering by substrate pit-patterning in SiGe films on Si(001)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grydlik, Martyna; Groiss, Heiko; Brehm, Moritz

2012-07-02

We show that suitable pit-patterning of a Si(001) substrate can strongly influence the nucleation and the propagation of dislocations during epitaxial deposition of Si-rich Si{sub 1-x}Ge{sub x} alloys, preferentially gettering misfit segments along pit rows. In particular, for a 250 nm layer deposited by molecular beam epitaxy at x{sub Ge} = 15%, extended film regions appear free of dislocations, by atomic force microscopy, as confirmed by transmission electron microscopy sampling. This result is quite general, as explained by dislocation dynamics simulations, which reveal the key role of the inhomogeneous distribution in stress produced by the pit-patterning.

Self-assembly of tin wires via phase transformation of heteroepitaxial germanium-tin on germanium substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei; Li, Lingzi; Yeo, Yee-Chia, E-mail: yeo@ieee.org

This work demonstrates and describes for the first time an unusual strain-relaxation mechanism by the formation and self-assembly of well-ordered tin wires during the thermal annealing of epitaxial Ge{sub 0.83}Sn{sub 0.17}-on-Ge(001) substrate. Fully strained germanium-tin alloys (Ge{sub 0.83}Sn{sub 0.17}) were epitaxially grown on Ge(001) substrate by molecular beam epitaxy. The morphological and compositional evolution of Ge{sub 0.83}Sn{sub 0.17} during thermal annealing is studied by atomic force microscopy, X-ray diffraction, transmission electron microscopy. Under certain annealing conditions, the Ge{sub 0.83}Sn{sub 0.17} layer decomposes into two stable phases, and well-defined Sn wires that are preferentially oriented along two orthogonal 〈100〉 azimuths aremore » formed. The formation of the Sn wires is related to the annealing temperature and the Ge{sub 0.83}Sn{sub 0.17} thickness, and can be explained by the nucleation of a grain with Sn islands on the outer front, followed by grain boundary migration. The Sn wire formation process is found to be thermally activated, and an activation enthalpy (E{sub c}) of 0.41 eV is extracted. This thermally activated phase transformation, i.e., 2D epitaxial layer to 3D wires, occurs via a mechanism akin to “cellular precipitation.” This synthesis route of Sn wires opens new possibilities for creation of nanoscale patterns at high-throughput without the need for lithography.« less

A review of molecular beam epitaxy of ferroelectric BaTiO3 films on Si, Ge and GaAs substrates and their applications

PubMed Central

Mazet, Lucie; Yang, Sang Mo; Kalinin, Sergei V; Schamm-Chardon, Sylvie; Dubourdieu, Catherine

2015-01-01

SrTiO3 epitaxial growth by molecular beam epitaxy (MBE) on silicon has opened up the route to the monolithic integration of various complex oxides on the complementary metal-oxide–semiconductor silicon platform. Among functional oxides, ferroelectric perovskite oxides offer promising perspectives to improve or add functionalities on-chip. We review the growth by MBE of the ferroelectric compound BaTiO3 on silicon (Si), germanium (Ge) and gallium arsenide (GaAs) and we discuss the film properties in terms of crystalline structure, microstructure and ferroelectricity. Finally, we review the last developments in two areas of interest for the applications of BaTiO3 films on silicon, namely integrated photonics, which benefits from the large Pockels effect of BaTiO3, and low power logic devices, which may benefit from the negative capacitance of the ferroelectric. PMID:27877816

Advanced germanium layer transfer for ultra thin body on insulator structure

NASA Astrophysics Data System (ADS)

Maeda, Tatsuro; Chang, Wen-Hsin; Irisawa, Toshifumi; Ishii, Hiroyuki; Hattori, Hiroyuki; Poborchii, Vladimir; Kurashima, Yuuichi; Takagi, Hideki; Uchida, Noriyuki

2016-12-01

We present the HEtero-Layer Lift-Off (HELLO) technique to obtain ultra thin body (UTB) Ge on insulator (GeOI) substrates. The transferred ultra thin Ge layers are characterized by the Raman spectroscopy measurements down to the thickness of ˜1 nm, observing a strong Raman intensity enhancement for high quality GeOI structure in ultra thin regime due to quantum size effect. This advanced Ge layer transfer technique enabled us to demonstrate UTB-GeOI nMOSFETs with the body thickness of only 4 nm.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Surface diffusion of Si, Ge and C adatoms on Si (001) substrate studied by the molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Chen, Zhi-Hui; Yu, Zhong-Yuan; Lu, Peng-Fei; Liu, Yu-Min

2009-10-01

Depositions of Si, Ge and C atoms onto a preliminary Si (001) substrate at different temperatures are investigated by using the molecular dynamics method. The mechanism of atomic self-assembling occurring locally on the flat terraces between steps is suggested. Diffusion and arrangement patterns of adatoms at different temperatures are observed. At 900 K, the deposited atoms are more likely to form dimers in the perpendicular [110] direction due to the more favourable movement along the perpendicular [110] direction. C adatoms are more likely to break or reconstruct the dimers on the substrate surface and have larger diffusion distances than Ge and Si adatoms. Exchange between C adatoms and substrate atoms are obvious and the epitaxial thickness is small. Total potential energies of adatoms and substrate atoms involved in the simulation cell are computed. When a newly arrived adatom reaches the stable position, the potential energy of the system will decrease and the curves turns into a ladder-like shape. It is found that C adatoms can lead to more reduction of the system energy and the potential energy of the system will increase as temperature increases.

Sublattice reversal in GaAs/Ge/GaAs (113)B heterostructures and its application to THz emitting devices based on a coupled multilayer cavity

NASA Astrophysics Data System (ADS)

Lu, Xiangmeng; Kumagai, Naoto; Minami, Yasuo; Kitada, Takahiro

2018-04-01

We fabricated a coupled multilayer cavity with a GaAs/Ge/GaAs sublattice reversal structure for terahertz emission application. Sublattice reversal in GaAs/Ge/GaAs was confirmed by comparing the anisotropic etching profile of an epitaxial sample with those of reference (113)A and (113)B GaAs substrates. The interfaces of GaAs/Ge/GaAs were evaluated at the atomic level by scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX) mapping. Defect-free GaAs/Ge/GaAs heterostructures were observed in STEM images and the sublattice lattice was directly seen through atomic arrangements in EDX mapping. A GaAs/AlAs coupled multilayer cavity with a sublattice reversal structure was grown on the (113)B GaAs substrate after the confirmation of sublattice reversal. Smooth GaAs/AlAs interfaces were formed over the entire region of the coupled multilayer cavity structure both below and above the Ge layer. Two cavity modes with a frequency difference of 2.9 THz were clearly observed.

Dislocation-free strained silicon-on-silicon by in-place bonding

NASA Astrophysics Data System (ADS)

Cohen, G. M.; Mooney, P. M.; Paruchuri, V. K.; Hovel, H. J.

2005-06-01

In-place bonding is a technique where silicon-on-insulator (SOI) slabs are bonded by hydrophobic attraction to the underlying silicon substrate when the buried oxide is undercut in dilute HF. The bonding between the exposed surfaces of the SOI slab and the substrate propagates simultaneously with the buried oxide etching. As a result, the slabs maintain their registration and are referred to as "bonded in-place". We report the fabrication of dislocation-free strained silicon slabs from pseudomorphic trilayer Si/SiGe/SOI by in-place bonding. Removal of the buried oxide allows the compressively strained SiGe film to relax elastically and induce tensile strain in the top and bottom silicon films. The slabs remain bonded to the substrate by van der Waals forces when the wafer is dried. Subsequent annealing forms a covalent bond such that when the upper Si and the SiGe layer are removed, the bonded silicon slab remains strained.

Development of Mid-infrared GeSn Light Emitting Diodes on a Silicon Substrate

DTIC Science & Technology

2015-04-22

Materials, Heterostrucuture Semiconductor, Light Emitting Devices, Molecular Beam Epitaxy 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT...LED) structure. Optimization of traditional and hetero- P-i-N structures designed and grown on Ge-buffer Si (001) wafers using molecular beam epitaxy ...designed structures were grown on Ge-buffer Si (001) wafers using molecular beam epitaxy (MBE) with the low-temperature growth technique. (The Ge-buffer

Evaluation of GeO desorption behavior in the metal∕GeO2∕Ge structure and its improvement of the electrical characteristics

PubMed Central

Oniki, Yusuke; Koumo, Hideo; Iwazaki, Yoshitaka; Ueno, Tomo

2010-01-01

The relation between germanium monoxide (GeO) desorption and either improvement or deterioration in electrical characteristics of metal∕GeO2∕Ge capacitors fabricated by thermal oxidation has been investigated. In the metal∕GeO2∕Ge stack, two processes of GeO desorption at different sites and at different temperatures were observed by thermal desorption spectroscopy measurements. The electrical characteristics of as-oxidized metal∕GeO2∕Ge capacitors shows a large flat-band voltage shift and minority carrier generation due to the GeO desorption from the GeO2∕Ge interface during oxidation of Ge substrates. On the other hand, the electrical properties were drastically improved by a postmetallization annealing at low temperature resulting in a metal catalyzed GeO desorption from the top interface. PMID:20644659

Growth of strained Si/relaxed SiGe heterostructures on Si(110) substrates using solid-source molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Arimoto, Keisuke; Nakazawa, Hiroki; Mitsui, Shohei; Utsuyama, Naoto; Yamanaka, Junji; Hara, Kosuke O.; Usami, Noritaka; Nakagawa, Kiyokazu

2017-11-01

A strained Si/relaxed SiGe heterostructure grown on Si(110) substrate is attractive as a platform for high-hole-mobility Si-based electronic devices. To improve the electrical property, a smoother surface is desirable. In this study, we investigated surface morphology and microstructural aspects of strained Si/relaxed SiGe/Si(110) heterostructures grown by solid-source (SS) molecular beam epitaxy (MBE). It was revealed that SSMBE provides a way to grow strained Si/relaxed SiGe heterostructures with smooth surfaces. In addition, it was found that the strain in the SiGe layer of the SSMBE-grown sample is highly anisotropic whereas that of the GSMBE-grown sample is almost biaxially relaxed. Along with the surface morphology, the symmetry in degree of strain relaxation has implications for the electrical property. Results of a calculation shows that anisotropic strain is preferable for device application since it confines holes solely in the strained Si layer where hole mobility is enhanced.

Magnetic, Optical and Magneto-optical Properties of Ni2MnGe Alloy Films

NASA Astrophysics Data System (ADS)

Kim, R. J.; Kudryavtsev, Y. V.; Kim, K. W.

2005-03-01

The influence of atomic ordering on the magnetic, the optical and the magneto-optical (MO) properties of Ni2MnGe Heusler alloy (HA) films was investigated. The bulk Ni2MnGe HA was prepared by arc melting, and the films were deposited by flash evaporation onto glass substrates at several substrate temperatures from 150 to 730 K. The bulk Ni2MnGe HA exhibits the cubic L21 structure with a = b = c = 0.5761 nm, and the annealed (at 573 K) bulk alloy is in the tetragonal structure with a = b = 0.5720 nm and c = 0.5865 nm. While the films deposited at 720 K show a well-ordered L21 structure, the deposition at 150 K < T < 710 K results in the formation of a nanocrystalline or an amorphous microstructure. It was found the structural disorder in Ni2MnGe films induces lack of the ferromagnetic order and noticeable changes in the optical and MO response.

Effects of annealing on arrays of Ge nanocolumns formed by glancing angle deposition

NASA Astrophysics Data System (ADS)

Khare, C.; Gerlach, J. W.; Höche, T.; Fuhrmann, B.; Leipner, H. S.; Rauschenbach, B.

2012-10-01

Post-deposition thermal annealing of glancing angle deposited Ge nanocolumn arrays was carried out in a continuous Ar-flow at temperatures ranging from TA = 300 to 800 °C for different annealing durations. Morphological alterations and the recrystallization process induced by the thermal annealing treatment were investigated for the Ge nanocolumns deposited on planar and pre-patterned Si substrates. From X-ray diffraction (XRD) measurements, the films annealed at TA ≥ 500 °C were found to be polycrystalline. On planar Si substrates, at TA = 600 °C nanocolumns exhibited strong coarsening and merging, while a complete disintegration of the nanocolumns was detected at TA = 700 °C. The morphology of nanostructures deposited on pre-patterned substrates differs substantially, where the merging or column-disintegration effect was absent at elevated annealing temperatures. The two-arm-chevron nanostructures grown on pre-patterned substrates retained their complex shape and morphology, after extended annealing intervals. Investigations by transmission electron microscopy revealed nanocrystalline domains of the order of 5-30 nm (in diameter) present within the chevron structures after the annealing treatment.

High quality, giant crystalline-Ge stripes on insulating substrate by rapid-thermal-annealing of Sn-doped amorphous-Ge in solid-liquid coexisting region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumura, Ryo; JSPS Research Fellow, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083; Kai, Yuki

Formation of large-grain (≥30 μm) Ge crystals on insulating substrates is strongly desired to achieve high-speed thin-film transistors. For this purpose, we propose the methods of Sn-doping into amorphous-Ge combined with rapid-thermal-annealing (RTA) in the solid-liquid coexisting temperature region for the Ge-Sn alloy system. The densities of micro-crystal-nuclei formed in this temperature region become low by tuning the RTA temperature close to the liquidus curve, which enhances the lateral growth of GeSn. Thanks to the very small segregation coefficient of Sn, almost all Sn atoms segregate toward edges of the stripes during growth. Agglomeration of GeSn degrades the surface morphologies;more » however, it is significantly improved by lowering the initial Sn concentration. As a result, pure Ge with large crystal grains (∼40 μm) with smooth surface are obtained by optimizing the initial Sn concentration as low as 3 ∼ 5%. Lateral growth lengths are further increased through decreasing the number of nuclei in stripes by narrowing stripe width. In this way, high-crystallinity giant Ge crystals (∼200 μm) are obtained for the stripe width of 3 μm. This “Si-seed free” technique for formation of large-grain pure Ge crystals is very useful to realize high-performance thin-film devices on insulator.« less

Toward a III-V Multijunction Space Cell Technology on Si

NASA Technical Reports Server (NTRS)

Ringel, S. A.; Lueck, M. R.; Andre, C. L.; Fitzgerald, E. A.; Wilt, D. M.; Scheiman, D.

2007-01-01

High efficiency compound semiconductor solar cells grown on Si substrates are of growing interest in the photovoltaics community for both terrestrial and space applications. As a potential substrate for III-V compound photovoltaics, Si has many advantages over traditional Ge and GaAs substrates that include higher thermal conductivity, lower weight, lower material costs, and the potential to leverage the extensive manufacturing base of the Si industry. Such a technology that would retain high solar conversion efficiency at reduced weight and cost would result in space solar cells that simultaneously possess high specific power (W/kg) and high power density (W/m2). For terrestrial solar cells this would result in high efficiency III-V concentrators with improved thermal conductivity, reduced cost, and via the use of SiGe graded interlayers as active component layers the possibility of integrating low bandgap sub-cells that could provide for extremely high conversion efficiency.1 In addition to photovoltaics, there has been an historical interest in III-V/Si integration to provide optical interconnects in Si electronics, which has become of even greater relevance recently due to impending bottlenecks in CMOS based circuitry. As a result, numerous strategies to integrate GaAs with Si have been explored with the primary issue being the approx.4% lattice mismatch between GaAs and Si. Among these efforts, relaxed, compositionally-graded SiGe buffer layers where the substrate lattice constant is effectively tuned from Si to that of Ge so that a close lattice match to subsequent GaAs overlayers have shown great promise. With this approach, threading dislocation densities (TDDs) of approx.1 x 10(exp 6)/sq cm have been uniformly achieved in relaxed Ge layers on Si,5 leading to GaAs on Si with minority carrier lifetimes greater than 10 ns,6 GaAs single junction solar cells on Si with efficiencies greater than 18%,7 InGaAs CW laser diodes on Si,8 and room temperature GaInP red laser diodes on Si.9 Here we report on the first high performance dual junction GaInP/GaAs solar cells grown on Si using this promising SiGe engineered substrate approach.

Fabrication of multilayered Ge nanocrystals embedded in SiO xGeN y films

NASA Astrophysics Data System (ADS)

Gao, Fei; Green, Martin A.; Conibeer, Gavin; Cho, Eun-Chel; Huang, Yidan; Perez-Wurfl, Ivan; Flynn, Chris

2008-09-01

Multilayered Ge nanocrystals embedded in SiO xGeN y films have been fabricated on Si substrate by a (Ge + SiO 2)/SiO xGeN y superlattice approach, using a rf magnetron sputtering technique with a Ge + SiO 2 composite target and subsequent thermal annealing in N 2 ambient at 750 °C for 30 min. X-ray diffraction (XRD) measurement indicated the formation of Ge nanocrystals with an average size estimated to be 5.4 nm. Raman scattering spectra showed a peak of the Ge-Ge vibrational mode downward shifted to 299.4 cm -1, which was caused by quantum confinement of phonons in the Ge nanocrystals. Transmission electron microscopy (TEM) revealed that Ge nanocrystals were confined in (Ge + SiO 2) layers. This superlattice approach significantly improved both the size uniformity of Ge nanocrystals and their uniformity of spacing on the 'Z' growth direction.

Near infrared group IV optoelectronics and novel pre-cursors for CVD epitaxy

NASA Astrophysics Data System (ADS)

Hazbun, Ramsey Michael

Near infrared and mid infrared optoelectronic devices have become increasingly important for the telecommunications, security, and medical imaging industries. The addition of nitrogen to III-V alloys has been widely studied as a method of modifying the band gap for mid infrared (IR) applications. In xGa1-xSb1-y Ny/InAs strained-layer superlattices with type-II (staggered) energy offsets on GaSb substrates, were modeled using eight-band k˙p simulations to analyze the superlattice miniband energies. Three different zero-stress strain balance conditions are reported: fixed superlattice period thickness, fixed InAs well thickness, and fixed InxGa1-xSb 1-yNy barrier thickness. Optoelectronics have traditionally been the realm of III-V semiconductors due to their direct band gap, while integrated circuit chips have been the realm of Group IV semiconductors such as silicon because of its relative abundance and ease of use. Recently the alloying of Sn with Ge and Si has been shown to allow direct band-gap light emission. This presents the exciting prospect of integrating optoelectronics into current Group IV chip fabrication facilities. However, new approaches for low temperature growth are needed to realize these new SiGeSn alloys. Silicon-germanium epitaxy via ultra-high vacuum chemical vapor deposition has the advantage of allowing low process temperatures. Deposition processes are sensitive to substrate surface preparation and the time delay between oxide removal and epitaxial growth. A new monitoring process utilizing doped substrates and defect decoration etching is demonstrated to have controllable and unique sensitivity to interfacial contaminants. Doped substrates were prepared and subjected to various loading conditions prior to the growth of typical Si/SiGe bilayers. The defect densities were correlated to the concentration of interfacial oxygen suggesting this monitoring process may be an effective complement to monitoring via secondary ion mass spectrometry measurements. The deposition of silicon using tetrasilane as a vapor pre-cursor is described for an ultra-high vacuum chemical vapor deposition tool. The growth rates and morphology of the Si epitaxial layers over a range of temperatures and pressures are presented. In order to understand the suitability of tetrasilane for the growth of SiGe and SiGeSn alloys, the layers were characterized using transmission electron microscopy, x-ray diffraction, spectroscopic ellipsometry, atomic force microscopy, and secondary ion mass spectrometry. To date no n-type doping has been demonstrated in GeSn alloys grown via MBE. A GaP decomposition source was used to grow n-type phosphorus doped GeSn layers on p- Ge substrates. Doping concentrations were calibrated using SIMS measurements. GeSn/Ge heterojunction diodes were grown and fabricated into mesa devices. Diode parameters were extracted from current-voltage measurements. The effects of P and Sn concentrations, metallization, and mesa geometry on device performance are all discussed.

Trap density of GeNx/Ge interface fabricated by electron-cyclotron-resonance plasma nitridation

NASA Astrophysics Data System (ADS)

Fukuda, Yukio; Otani, Yohei; Toyota, Hiroshi; Ono, Toshiro

2011-07-01

We have investigated GeNx/Ge interface properties using Si3N4(7 nm)/GeNx(2 nm)/Ge metal-insulator-semiconductor structures fabricated by the plasma nitridation of Ge substrates using an electron-cyclotron-resonance-generated nitrogen plasma. The interface trap density (Dit) measured by the conductance method is found to be distributed symmetrically in the Ge band gap with a minimum Dit value lower than 3 × 1011 cm-2eV-1 near the midgap. This result may lead to the development of processes for the fabrication of p- and n-Ge Schottky-barrier (SB) source/drain metal-insulator-semiconductor field-effect transistors using chemically and thermally robust GeNx dielectrics as interlayers for SB source/drain contacts and high-κ gate dielectrics.

Sub-5 nm, globally aligned graphene nanoribbons on Ge(001)

DOE PAGES

Kiraly, Brian; Mannix, Andrew J.; Jacobberger, Robert M.; ...

2016-05-23

Graphene nanoribbons (GNRs) hold great promise for future electronics because of their edge and width dependent electronic bandgaps and exceptional transport properties. While significant progress toward such devices has been made, the field has been limited by difficulties achieving narrow widths, global alignment, and atomically pristine GNR edges on technologically relevant substrates. A recent advance has challenged these limits by using Ge(001) substrates to direct the bottom-up growth of GNRs with nearly pristine armchair edges and widths near ~10 nm via atmospheric pressure chemical vapor deposition. In this work, we extend the growth of GNRs on Ge(001) to ultra-high vacuummore » conditions and realize GNRs narrower than 5 nm. Armchair graphene nanoribbons directed along the Ge <110> surface directions are achieved with excellent width control and relatively large bandgaps. As a result, the bandgap magnitude and electronic uniformity make these new materials excellent candidates for future developments in nanoelectronics.« less

Rational design of monocrystalline (InP)(y)Ge(5-2y)/Ge/Si(100) semiconductors: synthesis and optical properties.

PubMed

Sims, Patrick E; Chizmeshya, Andrew V G; Jiang, Liying; Beeler, Richard T; Poweleit, Christian D; Gallagher, James; Smith, David J; Menéndez, José; Kouvetakis, John

2013-08-21

In this work, we extend our strategy previously developed to synthesize functional, crystalline Si(5-2y)(AlX)y {X = N,P,As} semiconductors to a new class of Ge-III-V hybrid compounds, leading to the creation of (InP)(y)Ge(5-2y) analogues. The compounds are grown directly on Ge-buffered Si(100) substrates using gas source MBE by tuning the interaction between Ge-based P(GeH3)3 precursors and In atoms to yield nanoscale "In-P-Ge3" building blocks, which then confer their molecular structure and composition to form the target solids via complete elimination of H2. The collateral production of reactive germylene (GeH2), via partial decomposition of P(GeH3)3, is achieved by simple adjustment of the deposition conditions, leading to controlled Ge enrichment of the solid product relative to the stoichiometric InPGe3 composition. High resolution XRD, XTEM, EDX, and RBS indicate that the resultant monocrystalline (InP)(y)Ge(5-2y) alloys with y = 0.3-0.7 are tetragonally strained and fully coherent with the substrate and possess a cubic diamond-like structure. Molecular and solid-state ab initio density functional theory (DFT) simulations support the viability of "In-P-Ge3" building-block assembly of the proposed crystal structures, which consist of a Ge parent crystal in which the P atoms form a third-nearest-neighbor sublattice and "In-P" dimers are oriented to exclude energetically unfavorable In-In bonding. The observed InP concentration dependence of the lattice constant is closely reproduced by DFT simulation of these model structures. Raman spectroscopy and ellipsometry are also consistent with the "In-P-Ge3" building-block interpretation of the crystal structure, while the observation of photoluminescence suggests that (InP)(y)Ge(5-2y) may have important optoelectronic applications.

Structural properties of templated Ge quantum dot arrays: impact of growth and pre-pattern parameters

NASA Astrophysics Data System (ADS)

Tempeler, J.; Danylyuk, S.; Brose, S.; Loosen, P.; Juschkin, L.

2018-07-01

In this study we analyze the impact of process and growth parameters on the structural properties of germanium (Ge) quantum dot (QD) arrays. The arrays were deposited by molecular-beam epitaxy on pre-patterned silicon (Si) substrates. Periodic arrays of pits with diameters between 120 and 20 nm and pitches ranging from 200 nm down to 40 nm were etched into the substrate prior to growth. The structural perfection of the two-dimensional QD arrays was evaluated based on SEM images. The impact of two processing steps on the directed self-assembly of Ge QD arrays is investigated. First, a thin Si buffer layer grown on a pre-patterned substrate reshapes the pre-pattern pits and determines the nucleation and initial shape of the QDs. Subsequently, the deposition parameters of the Ge define the overall shape and uniformity of the QDs. In particular, the growth temperature and the deposition rate are relevant and need to be optimized according to the design of the pre-pattern. Applying this knowledge, we are able to fabricate regular arrays of pyramid shaped QDs with dot densities up to 7.2 × 1010 cm‑2.

Structural properties of templated Ge quantum dot arrays: impact of growth and pre-pattern parameters.

PubMed

Tempeler, J; Danylyuk, S; Brose, S; Loosen, P; Juschkin, L

2018-07-06

In this study we analyze the impact of process and growth parameters on the structural properties of germanium (Ge) quantum dot (QD) arrays. The arrays were deposited by molecular-beam epitaxy on pre-patterned silicon (Si) substrates. Periodic arrays of pits with diameters between 120 and 20 nm and pitches ranging from 200 nm down to 40 nm were etched into the substrate prior to growth. The structural perfection of the two-dimensional QD arrays was evaluated based on SEM images. The impact of two processing steps on the directed self-assembly of Ge QD arrays is investigated. First, a thin Si buffer layer grown on a pre-patterned substrate reshapes the pre-pattern pits and determines the nucleation and initial shape of the QDs. Subsequently, the deposition parameters of the Ge define the overall shape and uniformity of the QDs. In particular, the growth temperature and the deposition rate are relevant and need to be optimized according to the design of the pre-pattern. Applying this knowledge, we are able to fabricate regular arrays of pyramid shaped QDs with dot densities up to 7.2 × 10 10 cm -2 .

Coated semiconductor devices for neutron detection

DOEpatents

Klann, Raymond T.; McGregor, Douglas S.

2002-01-01

A device for detecting neutrons includes a semi-insulated bulk semiconductor substrate having opposed polished surfaces. A blocking Schottky contact comprised of a series of metals such as Ti, Pt, Au, Ge, Pd, and Ni is formed on a first polished surface of the semiconductor substrate, while a low resistivity ("ohmic") contact comprised of metals such as Au, Ge, and Ni is formed on a second, opposed polished surface of the substrate. In one embodiment, n-type low resistivity pinout contacts comprised of an Au/Ge based eutectic alloy or multi-layered Pd/Ge/Ti/Au are also formed on the opposed polished surfaces and in contact with the Schottky and ohmic contacts. Disposed on the Schottky contact is a neutron reactive film, or coating, for detecting neutrons. The coating is comprised of a hydrogen rich polymer, such as a polyolefin or paraffin; lithium or lithium fluoride; or a heavy metal fissionable material. By varying the coating thickness and electrical settings, neutrons at specific energies can be detected. The coated neutron detector is capable of performing real-time neutron radiography in high gamma fields, digital fast neutron radiography, fissile material identification, and basic neutron detection particularly in high radiation fields.

Adhesion of Germanium Electrode on Nickel Substrate for Lithium Ion Battery Applications

NASA Astrophysics Data System (ADS)

Jeyaranjan, Aadithya

Lithium ion batteries (LIBs) have gained increasing popularity due to their high potential, low self-discharge, zero priming and minimal memory effect. However, the emergence of electrical vehicles and hybrid electrical vehicles in the automobile industry, where LIBs are predominantly in use, instilled a need to improve LIB batteries by experimenting with new materials. Graphite, the commonly used anode material for LIBs suffers from low theoretical capacity (372 mA h g-1) and torpid rate performance. Germanium (Ge) seems to be a promising substitute of carbon due to its high theoretical capacity, high Li+ diffusivity and electrical conductivity. However, Ge undergoes large volumetric change (+/-370%). This causes deboning of the thin film Ge electrode from the substrate current collector, causing a rapid decrease in the electrolytic performance. The process of ion beam mixing claims to have overcome this problem. In our current study, the adhesion strength of Ge thin film over Nickel (Ni) substrate (with and without ion beam mixing) is being measured using nanoindentation and the superlayer indentation test. Nanoindentation is one of the popular techniques to measure the mechanical properties and adhesion of thin film coatings. In this technique, a very small indenter of a desired geometry indents the film/substrate pair and the work of adhesion is calculated by knowing the plastic depth of indentation and the radius of indentation. Superlayer indentation is analogous to normal indentation but with a highly stressed superlayer on top to restrict the out-of-plane displacements, it reduces the plastic pile up around the indenter tip. The results from our study strongly suggest the possibility of dramatically increasing the adhesion strength by ion bombardment, which can be achieved by atomic level intermixing of the film/substrate pair. These, in turn, suggest that Ge could be an effective successor to graphite in the near future.

Contact Angles and Surface Tension of Germanium-Silicon Melts

NASA Technical Reports Server (NTRS)

Croell, A.; Kaiser, N.; Cobb, S.; Szofran, F. R.; Volz, M.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Precise knowledge of material parameters is more and more important for improving crystal growth processes. Two important parameters are the contact (wetting) angle and the surface tension, determining meniscus shapes and surface-tension driven flows in a variety of methods (Czochralski, EFG, floating-zone, detached Bridgman growth). The sessile drop technique allows the measurement of both parameters simultaneously and has been used to measure the contact angles and the surface tension of Ge(1-x)Si(x) (0 less than or equal to x less than or equal to 1.3) alloys on various substrate materials. Fused quartz, Sapphire, glassy carbon, graphite, SiC, carbon-based aerogel, pyrolytic boron nitride (pBN), AIN, Si3N4, and polycrystalline CVD diamond were used as substrate materials. In addition, the effect of different cleaning procedures and surface treatments on the wetting behavior were investigated. Measurements were performed both under dynamic vacuum and gas atmospheres (argon or forming gas), with temperatures up to 1100 C. In some experiments, the sample was processed for longer times, up to a week, to investigate any changes of the contact angle and/or surface tension due to slow reactions with the substrate. For pure Ge, stable contact angles were found for carbon-based substrates and for pBN, for Ge(1-x)Si(x) only for pBN. The highest wetting angles were found for pBN substrates with angles around 170deg. For the surface tension of Ge, the most reliable values resulted in gamma(T) = (591- 0.077 (T-T(sub m)) 10(exp -3)N/m. The temperature dependence of the surface tension showed similar values for Ge(1-x)Si(x), around -0.08 x 10(exp -3)N/m K, and a compositional dependence of 2.2 x 10(exp -3)N/m at%Si.

Electrical and structural properties of In-implanted Si 1–xGe x alloys

DOE PAGES

Feng, Ruixing; Kremer, F.; Sprouster, D. J.; ...

2016-01-14

Here, we report on the effects of dopant concentration and substrate stoichiometry on the electrical and structural properties of In-implanted Si 1–xGe x alloys. Correlating the fraction of electrically active In atoms from Hall Effect measurements with the In atomic environment determined by X-ray absorption spectroscopy, we observed the transition from electrically active, substitutional In at low In concentration to electrically inactive metallic In at high In concentration. The In solid-solubility limit has been quantified and was dependent on the Si 1–xGe x alloy stoichiometry; the solid-solubility limit increased as the Ge fraction increased. This result was consistent with densitymore » functional theory calculations of two In atoms in a Si 1–xGe x supercell that demonstrated that In–In pairing was energetically favorable for x ≲ 0.7 and energetically unfavorable for x ≳ 0.7. Transmission electron microscopy imaging further complemented the results described earlier with the In concentration and Si 1–xGe x alloy stoichiometry dependencies readily visible. We have demonstrated that low resistivity values can be achieved with In implantation in Si 1–xGe x alloys, and this combination of dopant and substrate represents an effective doping protocol.« less

Defect and interface analyses of non-stoichiometric n-type GaSb thin films grown on Ge(100) substrates by rapid thermal annealing

NASA Astrophysics Data System (ADS)

Nishimoto, Naoki; Fujihara, Junko; Yoshino, Katsumi

2018-05-01

In this study, Ga0.6Sb0.4 thin films were grown on quartz and Ge(100) 1° off-axis substrates by RF magnetron sputtering at 500 °C. Ga0.6Sb0.4/Ge(100) shows n-type conductivity at room temperature (RT) and p-type conductivity at low temperatures, whereas undoped GaSb thin films exhibit p-type conductivity, irrespective of their growth methods and conditions. Their electrical properties were determined by rapid thermal annealing, which revealed that Ga0.6Sb0.4/Ge(100) contains two types of acceptors and two types of donors. The acceptors are considered to be GaSb and electrically active sites on dislocations originating at the Ga0.6Sb0.4/Ge(100) interface, while donors are believed to be Gai and electrically active sites originating at the Ga0.6Sb0.4/Ge(100) interface. In these acceptors and donors, the shallow donor concentration is higher than the shallow acceptor concentration, and the shallow donor level is deeper than the shallow acceptor level. Thus, we concluded that Ga0.6Sb0.4/Ge(100) shows n-type conductivity at RT due to electrically active sites originating at the Ga0.6Sb0.4/Ge(100) interface and native defects originating from excess Ga.

Heterostructure solar cells

NASA Technical Reports Server (NTRS)

Chang, K. I.; Yeh, Y. C. M.; Iles, P. A.; Morris, R. K.

1987-01-01

The performance of gallium arsenide solar cells grown on Ge substrates is discussed. In some cases the substrate was thinned to reduce overall cell weight with good ruggedness. The conversion efficiency of 2 by 2 cm cells under AMO reached 17.1 percent with a cell thickness of 6 mils. The work described forms the basis for future cascade cell structures, where similar interconnecting problems between the top cell and the bottom cell must be solved. Applications of the GaAs/Ge solar cell in space and the expected payoffs are discussed.

Effects of patterning induced stress relaxation in strained SOI/SiGe layers and substrate

NASA Astrophysics Data System (ADS)

Hermann, P.; Hecker, M.; Renn, F.; Rölke, M.; Kolanek, K.; Rinderknecht, J.; Eng, L. M.

2011-06-01

Local stress fields in strained silicon structures important for CMOS technology are essentially related to size effects and properties of involved materials. In the present investigation, Raman spectroscopy was utilized to analyze the stress distribution within strained silicon (sSi) and silicon-germanium (SiGe) island structures. As a result of the structuring of initially unpatterned strained films, a size-dependent relaxation of the intrinsic film stresses was obtained in agreement with model calculations. This changed stress state in the features also results in the appearance of opposing stresses in the substrate underneath the islands. Even for strained island structures on top of silicon-on-insulator (SOI) wafers, corresponding stresses in the silicon substrate underneath the oxide were detected. Within structures, the stress relaxation is more pronounced for islands on SOI substrates as compared to those on bulk silicon substrates.

Si-Based Germanium Tin Semiconductor Lasers for Optoelectronic Applications

NASA Astrophysics Data System (ADS)

Al-Kabi, Sattar H. Sweilim

Silicon-based materials and optoelectronic devices are of great interest as they could be monolithically integrated in the current Si complementary metal-oxide-semiconductor (CMOS) processes. The integration of optoelectronic components on the CMOS platform has long been limited due to the unavailability of Si-based laser sources. A Si-based monolithic laser is highly desirable for full integration of Si photonics chip. In this work, Si-based germanium-tin (GeSn) lasers have been demonstrated as direct bandgap group-IV laser sources. This opens a completely new avenue from the traditional III-V integration approach. In this work, the material and optical properties of GeSn alloys were comprehensively studied. The GeSn films were grown on Ge-buffered Si substrates in a reduced pressure chemical vapor deposition system with low-cost SnCl4 and GeH4 precursors. A systematic study was done for thin GeSn films (thickness 400 nm) with Sn composition 5 to 17.5%. The room temperature photoluminescence (PL) spectra were measured that showed a gradual shift of emission peaks towards longer wavelength as Sn composition increases. Strong PL intensity and low defect density indicated high material quality. Moreover, the PL study of n-doped samples showed bandgap narrowing compared to the unintentionally p-doped (boron) thin films with similar Sn compositions. Finally, optically pumped GeSn lasers on Si with broad wavelength coverage from 2 to 3 mum were demonstrated using high-quality GeSn films with Sn compositions up to 17.5%. The achieved maximum Sn composition of 17.5% broke the acknowledged Sn incorporation limit using similar deposition chemistry. The highest lasing temperature was measured at 180 K with an active layer thickness as thin as 270 nm. The unprecedented lasing performance is due to the achievement of high material quality and a robust fabrication process. The results reported in this work show a major advancement towards Si-based electrically pumped mid-infrared laser sources for integrated photonics.

Croissance epitaxiale de GaAs sur substrats de Ge par epitaxie par faisceaux chimiques

NASA Astrophysics Data System (ADS)

Belanger, Simon

La situation energetique et les enjeux environnementaux auxquels la societe est confrontee entrainent un interet grandissant pour la production d'electricite a partir de l'energie solaire. Parmi les technologies actuellement disponibles, la filiere du photovoltaique a concentrateur solaire (CPV pour concentrator photovoltaics) possede un rendement superieur et mi potentiel interessant a condition que ses couts de production soient competitifs. La methode d'epitaxie par faisceaux chimiques (CBE pour chemical beam epitaxy) possede plusieurs caracteristiques qui la rendent interessante pour la production a grande echelle de cellules photovoltaiques a jonctions multiples a base de semi-conducteurs III-V. Ce type de cellule possede la meilleure efficacite atteinte a ce jour et est utilise sur les satellites et les systemes photovoltaiques a concentrateur solaire (CPV) les plus efficaces. Une des principales forces de la technique CBE se trouve dans son potentiel d'efficacite d'utilisation des materiaux source qui est superieur a celui de la technique d'epitaxie qui est couramment utilisee pour la production a grande echelle de ces cellules. Ce memoire de maitrise presente les travaux effectues dans le but d'evaluer le potentiel de la technique CBE pour realiser la croissance de couches de GaAs sur des substrats de Ge. Cette croissance constitue la premiere etape de fabrication de nombreux modeles de cellules solaires a haute performance decrites plus haut. La realisation de ce projet a necessite le developpement d'un procede de preparation de surface pour les substrats de germanium, la realisation de nombreuses sceances de croissance epitaxiale et la caracterisation des materiaux obtenus par microscopie optique, microscopie a force atomique (AFM), diffraction des rayons-X a haute resolution (HRXRD), microscopie electronique a transmission (TEM), photoluminescence a basse temperature (LTPL) et spectrometrie de masse des ions secondaires (SIMS). Les experiences ont permis de confirmer l'efficacite du procede de preparation de surface et d'identifier les conditions de croissance optimales. Les resultats de caracterisation indiquent que les materiaux obtenus presentent une tres faible rugosite de surface, une bonne qualite cristalline et un dopage residuel relativement important. De plus, l'interface GaAs/Ge possede une faible densite de defauts. Finalement, la diffusion d'arsenic dans le substrat de germanium est comparable aux valeurs trouvees dans la litterature pour la croissance a basse temperature avec les autres procedes d'epitaxie courants. Ces resultats confirment que la technique d'epitaxie par faisceaux chimiques (CBE) permet de produire des couches de GaAs sur Ge de qualite adequate pour la fabrication de cellules solaires a haute performance. L'apport a la communaute scientifique a ete maximise par le biais de la redaction d'un article soumis a la revue Journal of Crystal Growth et la presentation des travaux a la conference Photovoltaics Canada 2010 . Mots-cles : Epitaxie par jets chimiques, Chemical beam epitaxy, CBE, MOMBE, Germanium, GaAs, Ge

Electronic structures of GeSi nanoislands grown on pit-patterned Si(001) substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Han, E-mail: Dabombyh@aliyun.com; Yu, Zhongyuan

2014-11-15

Patterning pit on Si(001) substrate prior to Ge deposition is an important approach to achieve GeSi nanoislands with high ordering and size uniformity. In present work, the electronic structures of realistic uncapped pyramid, dome, barn and cupola nanoislands grown in (105) pits are systematically investigated by solving Schrödinger equation for heavy-hole, which resorts to inhomogeneous strain distribution and nonlinear composition-dependent band parameters. Uniform, partitioned and equilibrium composition profile (CP) in nanoisland and inverted pyramid structure are simulated separately. We demonstrate the huge impact of composition profile on localization of heavy-hole: wave function of ground state is confined near pit facetsmore » for uniform CP, at bottom of nanoisland for partitioned CP and at top of nanoisland for equilibrium CP. Moreover, such localization is gradually compromised by the size effect as pit filling ratio or pit size decreases. The results pave the fundamental guideline of designing nanoislands on pit-patterned substrates for desired applications.« less

Graphene growth on Ge(100)/Si(100) substrates by CVD method.

PubMed

Pasternak, Iwona; Wesolowski, Marek; Jozwik, Iwona; Lukosius, Mindaugas; Lupina, Grzegorz; Dabrowski, Pawel; Baranowski, Jacek M; Strupinski, Wlodek

2016-02-22

The successful integration of graphene into microelectronic devices is strongly dependent on the availability of direct deposition processes, which can provide uniform, large area and high quality graphene on nonmetallic substrates. As of today the dominant technology is based on Si and obtaining graphene with Si is treated as the most advantageous solution. However, the formation of carbide during the growth process makes manufacturing graphene on Si wafers extremely challenging. To overcome these difficulties and reach the set goals, we proposed growth of high quality graphene layers by the CVD method on Ge(100)/Si(100) wafers. In addition, a stochastic model was applied in order to describe the graphene growth process on the Ge(100)/Si(100) substrate and to determine the direction of further processes. As a result, high quality graphene was grown, which was proved by Raman spectroscopy results, showing uniform monolayer films with FWHM of the 2D band of 32 cm(-1).

Thermodynamic analysis of vapor-phase epitaxial growth of GaAsN on Ge

NASA Astrophysics Data System (ADS)

Kawano, Jun; Kangawa, Yoshihiro; Ito, Tomonori; Kakimoto, Koichi; Koukitu, Akinori

2012-03-01

In this paper, we use thermodynamic analysis to determine how the nitrogen (N) ratio in the source gases affects the solid composition of coherently grown GaAs1-xNx(x˜0.03). The source gases for Ga, As, and N are trimethylgallium ((CH3)3Ga), arsine (AsH3), and ammonia (NH3), respectively. The growth occurs on a Ge substrate, and the analysis includes the stress from the substrate-crystal lattice mismatch. Calculation results indicate that to have just a few percent N incorporation into the grown solid, the V/III ratio in the source gases should be several thousands and the input-gas partial-pressure ratio NH3/(NH3+AsH3) should exceed 0.99. We also find that the lattice mismatch stress from the Ge substrate increases the V/III source-gas ratio required for stable growth, whereas an increase in input Ga partial pressure ratio has the opposite effect.

X-ray photoelectron-diffraction study of intermixing and morphology at the Ge/Si(001) and Ge/Sb/Si(001) interface

NASA Astrophysics Data System (ADS)

Gunnella, R.; Castrucci, P.; Pinto, N.; Davoli, I.; Sébilleau, D.; de Crescenzi, M.

1996-09-01

We used the XPD (x-ray photoelectron diffraction) and AED (Auger electron diffraction) from Ge core levels to probe the crystalline structure of 3 and 6 ML of Ge epitaxially grown by molecular-beam epitaxy on the Si(001) surface. In order to check the film tetragonal distortion and the pseudomorphic growth morphology, we used two different temperatures of the substrate during the deposition: room temperature and 400 °C. Evidence for an interfacial intermixing has been found by means of the observation of the angular behavior of the intensity of the emitted electrons. We also investigated the effects of Sb as a surfactant on such an interface. In this case indications of a laminar growth of strained Ge overlayer with reduced intermixing is obtained when 1 ML of Sb is predeposited on the substrate. Furthermore making use of a multiple-scattering approach to reproduce the experimental XPD patterns, a higher amount of accessible information on the morphology of the interface, beyond the determination of the strain content, is obtained.

Response of single junction GaAs/GaAs and GaAs/Ge solar cells to multiple doses of 1 MeV electrons

NASA Technical Reports Server (NTRS)

Meier, D. L.; Szedon, J. R.; Bartko, J.; Chung, M. A.

1989-01-01

A comparison of the radiation tolerance of MOCVD-grown GaAs cells and GaAs/Ge cells was undertaken using 1 MeV electrons. The GaAs/Ge cells are somewhat more tolerant of 1 MeV electron irradiation and more responsive to annealing than are the GaAs/GaAs cells examined in this study. However, both types of cells suffer a greater degradation in efficiency than has been observed in other recent studies. The reason for this is not certain, but it may be associated with an emitter thickness which appears to be greater than desired. The deep level transient spectroscopy (DLTS) spectra following irradiation are not significantly different for the GaAs/Ge and the GaAs/GaAs cells, with each having just two peaks. The annealing behavior of these peaks is also similar in the two samples examined. It appears that no penalty in radiation tolerance, and perhaps some benefit, is associated with fabricating MOCVD GaAs cells on Ge substrates rather than GaAs substrates.

(113) Facets of Si-Ge/Si Islands; Atomic Scale Simulation

NASA Astrophysics Data System (ADS)

Kassem, Hassan

We have studied, by computer simulation, some static and vibrationnal proprieties of SiGe/Si islands. We have used a Valence Force Field combined to Monte Carlo technique to study the growth of Ge and SiGe on (001)Si substrates. We have focalised on the case of large pyramidal islands presenting (113) facets on the free (001)Si surface with various non uniform composition inside the islands. The deformation inside the islands and Raman spectroscopy are discussed.

Nucleation-controlled low-temperature solid-phase crystallization for Sn-doped polycrystalline-Ge film on insulator with high carrier mobility (˜550 cm2/V s)

NASA Astrophysics Data System (ADS)

Xu, Chang; Gao, Hongmiao; Sugino, Takayuki; Miyao, Masanobu; Sadoh, Taizoh

2018-06-01

High-speed thin-film transistors (TFTs) are required to develop the next generation of electronics, such as three-dimensional large-scale integrated circuits and advanced system-in-displays. For this purpose, high-carrier-mobility semiconductor films on insulator structures should be fabricated with low-temperature processing conditions (≤500 °C). To achieve this, we investigate solid-phase crystallization of amorphous-GeSn (a-GeSn) films (Sn concentration: 2% and thickness: 50-200 nm) on insulating substrates, where thin a-Si under-layers (thickness: 0-20 nm) are introduced between a-GeSn films and insulating substrates. The GeSn films are polycrystallized by annealing (450 °C, 20 h) for all samples irrespective of a-GeSn and a-Si thickness conditions, while the Si films remain amorphous. Analysis of crystal structures of GeSn films (thickness: 50 nm) reveals that grain sizes decrease from ˜10 μm to 2-3 μm by the introduction of a-Si under-layers (thickness: 3-20 nm). This phenomenon is attributed to the change in dominant nucleation sites from the interface to the bulk, which significantly decreases grain-boundary scattering of carriers through a decrease in the barrier heights at grain boundaries. Bulk-nucleation further becomes dominant by increasing the GeSn film thickness. As a result, a high carrier mobility of ˜550 cm2/V s is realized for GeSn films (thickness: 100 nm) grown with a-Si under-layers. This mobility is the largest among ever reported data for Ge and GeSn grown on an insulator. This technique will facilitate realization of high-speed TFTs for use in the next generation of electronics.

Density-functional theory molecular dynamics simulations of a-HfO2/a-SiO2/SiGe and a-HfO2/a-SiO2/Ge with a-SiO2 and a-SiO suboxide interfacial layers

NASA Astrophysics Data System (ADS)

Chagarov, Evgueni A.; Kavrik, Mahmut S.; Fang, Ziwei; Tsai, Wilman; Kummel, Andrew C.

2018-06-01

Comprehensive Density-Functional Theory (DFT) Molecular Dynamics (MD) simulations were performed to investigate interfaces between a-HfO2 and SiGe or Ge semiconductors with fully-stoichiometric a-SiO2 or sub-oxide SiO interlayers. The electronic structure of the selected stacks was calculated with a HSE06 hybrid functional. Simulations were performed before and after hydrogen passivation of residual interlayer defects. For the SiGe substrate with Ge termination prior to H passivation, the stacks with a-SiO suboxide interlayer (a-HfO2/a-SiO/SiGe) demonstrate superior electronic properties and wider band-gaps than the stacks with fully coordinated a-SiO2 interlayers (a-HfO2/a-SiO2/SiGe). After H passivation, most of the a-HfO2/a-SiO2/SiGe defects are passivated. To investigate effect of random placement of Si and Ge atoms additional simulations with a randomized SiGe slab were performed demonstrating improvement of electronic structure. For Ge substrates, before H passivation, the stacks with a SiO suboxide interlayer (a-HfO2/a-SiO/Ge) also demonstrate wider band-gaps than the stacks with fully coordinated a-SiO2 interlayers (a-HfO2/a-SiO2/Ge). However, even for a-HfO2/a-SiO/Ge, the Fermi level is shifted close to the conduction band edge (CBM) consistent with Fermi level pinning. Again, after H passivation, most of the a-HfO2/a-SiO2/Ge defects are passivated. The stacks with fully coordinated a-SiO2 interlayers have much stronger deformation and irregularity in the semiconductor (SiGe or Ge) upper layers leading to multiple under-coordinated atoms which create band-edge states and decrease the band-gap prior to H passivation.

Strained multilayer structures with pseudomorphic GeSiSn layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timofeev, V. A., E-mail: Vyacheslav.t@isp.nsc.ru; Nikiforov, A. I.; Tuktamyshev, A. R.

2016-12-15

The temperature and composition dependences of the critical thickness of the 2D–3D transition for a GeSiSn film on Si(100) have been studied. The regularities of the formation of multilayer structures with pseudomorphic GeSiSn layers directly on a Si substrate, without relaxed buffer layers, were investigated for the first time. The possibility of forming multilayer structures based on pseudomorphic GeSiSn layers has been shown and the lattice parameters have been determined using transmission electron microscopy. The grown structures demonstrate photoluminescence for Sn contents from 3.5 to 5% in GeSiSn layers.

Self-diffusion in compressively strained Ge

NASA Astrophysics Data System (ADS)

Kawamura, Yoko; Uematsu, Masashi; Hoshi, Yusuke; Sawano, Kentarou; Myronov, Maksym; Shiraki, Yasuhiro; Haller, Eugene E.; Itoh, Kohei M.

2011-08-01

Under a compressive biaxial strain of ˜ 0.71%, Ge self-diffusion has been measured using an isotopically controlled Ge single-crystal layer grown on a relaxed Si0.2Ge0.8 virtual substrate. The self-diffusivity is enhanced by the compressive strain and its behavior is fully consistent with a theoretical prediction of a generalized activation volume model of a simple vacancy mediated diffusion, reported by Aziz et al. [Phys. Rev. B 73, 054101 (2006)]. The activation volume of (-0.65±0.21) times the Ge atomic volume quantitatively describes the observed enhancement due to the compressive biaxial strain very well.

Atomistics of Ge deposition on Si(100) by atomic layer epitaxy.

PubMed

Lin, D S; Wu, J L; Pan, S Y; Chiang, T C

2003-01-31

Chlorine termination of mixed Ge/Si(100) surfaces substantially enhances the contrast between Ge and Si sites in scanning tunneling microscopy observations. This finding enables a detailed investigation of the spatial distribution of Ge atoms deposited on Si(100) by atomic layer epitaxy. The results are corroborated by photoemission measurements aided by an unusually large chemical shift between Cl adsorbed on Si and Ge. Adsorbate-substrate atomic exchange during growth is shown to be important. The resulting interface is thus graded, but characterized by a very short length scale of about one monolayer.

Single-layer dual germanene phases on Ag(111)

NASA Astrophysics Data System (ADS)

Lin, Chung-Huang; Huang, Angus; Pai, Woei Wu; Chen, Wei-Chuan; Chen, Ting-Yu; Chang, Tay-Rong; Yukawa, Ryu; Cheng, Cheng-Maw; Mou, Chung-Yu; Matsuda, Iwao; Chiang, T.-C.; Jeng, H.-T.; Tang, S.-J.

2018-02-01

Two-dimensional (2D) honeycomb lattices beyond graphene promise new physical properties such as quantum spin Hall effect. While there have been claims of growth of such lattices (silicene, germanene, stanene), their existence needs further support and their preparation and characterization remain a difficult challenge. Our findings suggest that two distinct phases associated with germanene, the analog of graphene made of germanium (Ge) instead of carbon, can be grown on Ag(111) as observed by scanning tunneling microscopy, low-energy electron diffraction, and angle-resolved photoemission spectroscopy. One such germanene exhibits an atom-resolved alternatively buckled full honeycomb lattice, which is tensile strained and partially commensurate with the substrate to form a striped phase (SP). The other, a quasifreestanding phase (QP), is also consistent with a honeycomb lattice with a lattice constant incommensurate with the substrate but very close to the theoretical value for freestanding germanene. The SP, with a lower atomic density, can be driven into the QP and coexist with the QP by additional Ge deposition. Band mapping and first-principles calculations with proposed SP and QP models reveal an interface state exists only in the SP but the characteristic σ band of freestanding germanene emerges only in the QP—this leads to an important conclusion that adlayer-substrate commensurability plays a key role to affect the electronic structure of germanene. The evolution of the dual germanene phases manifests the competitive formation of Ge-Ge covalent and Ge-Ag interfacial bonds.

Growth of high-Sn content (28%) GeSn alloy films by sputtering epitaxy

NASA Astrophysics Data System (ADS)

Zheng, Jun; Liu, Zhi; Zhang, Yongwang; Zuo, Yuhua; Li, Chuanbo; Xue, Chunlai; Cheng, Buwen; Wang, Qiming

2018-06-01

Crystalline GeSn thin films with Sn content up to 0.28 were deposited on Sn graded GeSn buffer on a Ge substrate at low temperatures by sputtering epitaxy. The structural properties of the high-Sn content GeSn alloy films were characterized by high resolution transmission electron microscopy and X-ray diffraction. The effect of annealing on the segregation of Sn in the high-Sn content GeSn film was investigated, and both the Ge0.72Sn0.28 and the Ge0.8Sn0.2 films were found to be stable after annealing at temperatures below 400 °C, which meets the needs of thermal budget for future photonic devices fabrication. The present results indicate that sputtering epitaxy is cost-effective method for growing high-Sn GeSn films.

Water-vapor-enhanced growth of Ge GeOx core shell nanowires and Si1-xGexOy nanowires

NASA Astrophysics Data System (ADS)

Hsu, Ting-Jui; Ko, Chih-Yuan; Lin, Wen-Tai

2007-09-01

The effects of moist Ar on the growth of Ge-GeOx core-shell nanowires (Ge-GeOx NWs) and Si1-xGexOy nanowires (SiGeONWs) on Si substrates without adding a metal catalyst via the carbothermal reduction of GeO2 powders at 1100 °C were studied. No significant nanowires were grown in dry Ar at a flow rate of 100-300 sccm until a bit of water in the range of 0.5-2 ml was loaded into the furnace. More water suppressed the growth of nanowires because of the exhaustion of more graphite powder. The growth of Ge-GeOx NWs and SiGeONWs follows the vapor-solid and vapor-liquid-solid processes, respectively. The present study showed that the water vapor serves as an oxidizer as well as a reducer at 1100 °C in enhancing the growth of SiGeONWs and Ge-GeOx NWs, respectively. The growth mechanisms of Ge-GeOx NWs and SiGeONWs are also discussed.

The Physical Electronics of Graphene on Germanium

NASA Astrophysics Data System (ADS)

Rojas Delgado, Richard

The properties of graphene make it an outstanding candidate for electronic-device applications, especially those that require no band gap but a high conductance. The conductance, involving both carrier mobility and carrier concentration, will depend critically on the substrate to which graphene is transferred. I demonstrate an exceptionally high conductance in graphene transferred to Ge(001) and provide an understanding of the mechanism. Essential in this understanding is an interfacial chemistry consisting of Ge oxide and suboxide layers that provide the necessary charges to dope the graphene sheet, and whose chemical behavior is such that one can obtain long-term stability in the conductance. In contrast, when high-quality graphene is grown directly on Ge (100), (111), or (110), the conductance is unexceptional, but oxidation of the surface is significantly delayed and slowed, relative to both clean Ge and Ge with graphene transferred to its surface. [2,3] I fabricate Hall bars in graphene transferred to Ge(001) and graphene grown on Ge(001) using atmospheric-pressure chemical vapor deposition (CVD) with methane precursors, and measure the sheet resistance and Hall effect from 300K to 10K. Values of mobility and carrier concentration are extracted. I obtain the highest combination of mobility and carrier concentration yet reported in graphene (suspended or supported) for temperatures from 10 to 300K. The implication is that the primary mechanisms for scattering charge in the graphene, roughness and a non-uniform electrostatic potential due to fixed charges, have limited effect when the substrate is oxidized Ge.

Metal-insulator transition characteristics of VO2 thin films grown on Ge(100) single crystals

NASA Astrophysics Data System (ADS)

Yang, Z.; Ko, C.; Ramanathan, S.

2010-10-01

Phase transitions exhibited by correlated oxides could be of potential relevance to the emerging field of oxide electronics. We report on the synthesis of high-quality VO2 thin films grown on single crystal Ge(100) substrates by physical vapor deposition and their metal-insulator transition (MIT) properties. Thermally triggered MIT is demonstrated with nearly three orders of magnitude resistance change across the MIT with transition temperatures of 67 °C (heating) and 61 °C (cooling). Voltage-triggered hysteretic MIT is observed at room temperature at threshold voltage of ˜2.1 V for ˜100 nm thickness VO2 films. Activation energies for electron transport in the insulating and conducting states are obtained from variable temperature resistance measurements. We further compare the properties of VO2 thin films grown under identical conditions on Si(100) single crystals. The VO2 thin films grown on Ge substrate show higher degree of crystallinity, slightly reduced compressive strain, larger resistance change across MIT compared to those grown on Si. Depth-dependent x-ray photoelectron spectroscopy measurements were performed to provide information on compositional variation trends in the two cases. These results suggest Ge could be a suitable substrate for further explorations of switching phenomena and devices for thin film functional oxides.

The curious case of exploding quantum dots: anomalous migration and growth behaviors of Ge under Si oxidation

PubMed Central

2013-01-01

We have previously demonstrated the unique migration behavior of Ge quantum dots (QDs) through Si3N4 layers during high-temperature oxidation. Penetration of these QDs into the underlying Si substrate however, leads to a completely different behavior: the Ge QDs ‘explode,’ regressing back almost to their origins as individual Ge nuclei as formed during the oxidation of the original nanopatterned SiGe structures used for their generation. A kinetics-based model is proposed to explain the anomalous migration behavior and morphology changes of the Ge QDs based on the Si flux generated during the oxidation of Si-containing layers. PMID:23618165

Nanoheteroepitaxy of gallium arsenide on strain-compliant silicon-germanium nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chin, Hock-Chun; Gong, Xiao; Yeo, Yee-Chia

Heterogeneous integration of high-quality GaAs on Si-based substrates using a selective migration-enhanced epitaxy (MEE) of GaAs on strain-compliant SiGe nanowires was demonstrated for the first time. The physics of compliance in nanoscale heterostructures was captured and studied using finite-element simulation. It is shown that nanostructures can provide additional substrate compliance for strain relief and therefore contribute to the formation of defect-free GaAs on SiGe. Extensive characterization using scanning electron microscopy and cross-sectional transmission electron microscopy was performed to illustrate the successful growth of GaAs on SiGe nanowire. Raman and Auger electron spectroscopy measurements further confirmed the quality of the GaAsmore » grown and the high growth selectivity of the MEE process.« less

Photoluminescence and electroluminescence from Ge/strained GeSn/Ge quantum wells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Chung-Yi; Chang, Chih-Chiang; Huang, Chih-Hsiung

2016-08-29

Ge/strained GeSn/Ge quantum wells are grown on a 300 mm Si substrate by chemical vapor deposition. The direct bandgap emission from strained GeSn is observed in the photoluminescence spectra and is enhanced by Al{sub 2}O{sub 3}/SiO{sub 2} passivation due to the field effect. The electroluminescence of the direct bandgap emission of strained GeSn is also observed from the Ni/Al{sub 2}O{sub 3}/GeSn metal-insulator-semiconductor tunneling diodes. Electroluminescence is a good indicator of GeSn material quality, since defects in GeSn layers degrade the electroluminescence intensity significantly. At the accumulation bias, the holes in the Ni gate electrode tunnel to the strained n-type GeSn layermore » through the ultrathin Al{sub 2}O{sub 3} and recombine radiatively with electrons. The emission wavelength of photoluminescence and electroluminescence can be tuned by the Sn content.« less

III-V compound semiconductor growth on silicon via germanium buffer and surface passivation for CMOS technology

NASA Astrophysics Data System (ADS)

Choi, Donghun

Integration of III-V compound semiconductors on silicon substrates has recently received much attention for the development of optoelectronic and high speed electronic devices. However, it is well known that there are some key challenges for the realization of III-V device fabrication on Si substrates: (i) the large lattice mismatch (in case of GaAs: 4.1%), and (ii) the formation of antiphase domain (APD) due to the polar compound semiconductor growth on non-polar elemental structure. Besides these growth issues, the lack of a useful surface passivation technology for compound semiconductors has precluded development of metal-oxide-semiconductor (MOS) devices and causes high surface recombination parasitics in scaled devices. This work demonstrates the growth of high quality III-V materials on Si via an intermediate Ge buffer layer and some surface passivation methods to reduce interface defect density for the fabrication of MOS devices. The initial goal was to achieve both low threading dislocation density (TDD) and low surface roughness on Ge-on-Si heterostructure growth. This was achieved by repeating a deposition-annealing cycle consisting of low temperature deposition + high temperature-high rate deposition + high temperature hydrogen annealing, using reduced-pressure chemical-vapor deposition (CVD). We then grew III-V materials on the Ge/Si virtual substrates using molecular-beam epitaxy (MBE). The relationship between initial Ge surface configuration and antiphase boundary formation was investigated using surface reflection high-energy electron diffraction (RHEED) patterns and atomic force microscopy (AFM) image analysis. In addition, some MBE growth techniques, such as migration enhanced epitaxy (MEE) and low temperature GaAs growth, were adopted to improve surface roughness and solve the Ge self-doping problem. Finally, an Al2O3 gate oxide layer was deposited using atomic-layer-deposition (ALD) system after HCl native oxide etching and ALD in-situ pre-annealing at 400 °C. A 100 nm thick aluminum layer was deposited to form the gate contact for a MOS device fabrication. C-V measurement results show very small frequency dispersion and 200-300 mV hysteresis, comparable to our best results for InGaAs/GaAs MOS structures on GaAs substrate. Most notably, the quasi-static C-V curve demonstrates clear inversion layer formation. I-V curves show a reasonable leakage current level. The inferred midgap interface state density, Dit, of 2.4 x 1012 eV-1cm-2 was calculated by combined high-low frequency capacitance method. In addition, we investigated the interface properties of amorphous LaAlO 3/GaAs MOS capacitors fabricated on GaAs substrate. The surface was protected during sample transfer between III-V and oxide molecular beam deposition (MBD) chambers by a thick arsenic-capping layer. An annealing method, a low temperature-short time RTA followed by a high temperature RTA, was developed, yielding extremely small hysteresis (˜ 30 mV), frequency dispersion (˜ 60 mV), and interface trap density (mid 1010 eV-1cm -2). We used capacitance-voltage (C-V) and current-voltage (I-V) measurements for electrical characterization of MOS devices, tapping-mode AFM for surface morphology analysis, X-ray photoelectron spectroscopy (XPS) for chemical elements analysis of interface, cross section transmission-electron microscopy (TEM), X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), and photoluminescence (PL) measurement for film quality characterization. This successful growth and appropriate surface treatments of III-V materials provides a first step for the fabrication of III-V optical and electrical devices on the same Si-based electronic circuits.

On the crystallization of amorphous germanium films

NASA Astrophysics Data System (ADS)

Edelman, F.; Komem, Y.; Bendayan, M.; Beserman, R.

1993-06-01

The incubation time for crystallization of amorphous Ge (a-Ge) films, deposited by e-gun, was studied as a function of temperature between 150 and 500°C by means of both in situ transmission electron microscopy and Raman scattering spectroscopy. The temperature dependence of t0 follows an Arrhenius curve with an activation energy of 2.0 eV for free-sustained a-Ge films. In the case where the a-Ge films were on Si 3N 4 substrate, the activation energy of the incubation process was 1.3 eV.

Kirkendall void formation in reverse step graded Si1-xGex/Ge/Si(001) virtual substrates

NASA Astrophysics Data System (ADS)

Sivadasan, Vineet; Rhead, Stephen; Leadley, David; Myronov, Maksym

2018-02-01

Formation of Kirkendall voids is demonstrated in the Ge underlayer of reverse step graded Si1-xGex/Ge buffer layers grown on Si(001) using reduced pressure chemical vapour deposition (RP-CVD). This phenomenon is seen when the constant composition Si1-xGex layer is grown at high temperatures and for x ≤ 0.7. The density and size of the spherical voids can be tuned by changing Ge content in the Si1-xGex and other growth parameters.

Thermal Improvement and Stability of Si3N4/GeNx/p- and n-Ge Structures Prepared by Electron-Cyclotron-Resonance Plasma Nitridation and Sputtering at Room Temperature

NASA Astrophysics Data System (ADS)

Fukuda, Yukio; Okamoto, Hiroshi; Iwasaki, Takuro; Izumi, Kohei; Otani, Yohei; Ishizaki, Hiroki; Ono, Toshiro

2012-09-01

This paper reports on the thermal improvement of Si3N4/GeNx/Ge structures. After the Si3N4 (5 nm)/GeNx (2 nm) stacks were prepared on Ge substrates by electron-cyclotron-resonance plasma nitridation and sputtering at room temperature, they were thermally annealed in atmospheric N2 + 10% H2 ambient at temperatures from 400 to 600 °C. It was demonstrated that the electronic properties of the GeNx/Ge interfaces were thermally improved at temperatures of up to 500 °C with a minimum interface trap density (Dit) of ˜1×1011 cm-2 eV-1 near the Ge midgap, whereas the interface properties were slightly degraded after annealing at 600 °C with a minimum Dit value of ˜4×1011 cm-2 eV-1.

Room Temperature Ferromagnetic, Anisotropic, Germanium Rich FeGe(001) Alloys

PubMed Central

Lungu, George A.; Apostol, Nicoleta G.; Stoflea, Laura E.; Costescu, Ruxandra M.; Popescu, Dana G.; Teodorescu, Cristian M.

2013-01-01

Ferromagnetic FexGe1−x with x = 2%–9% are obtained by Fe deposition onto Ge(001) at high temperatures (500 °C). Low energy electron diffraction (LEED) investigation evidenced the preservation of the (1 × 1) surface structure of Ge(001) with Fe deposition. X-ray photoelectron spectroscopy (XPS) at Ge 3d and Fe 2p core levels evidenced strong Fe diffusion into the Ge substrate and formation of Ge-rich compounds, from FeGe3 to approximately FeGe2, depending on the amount of Fe deposited. Room temperature magneto-optical Kerr effect (MOKE) evidenced ferromagnetic ordering at room temperature, with about 0.1 Bohr magnetons per Fe atom, and also a clear uniaxial magnetic anisotropy with the in-plane [110] easy magnetization axis. This compound is a good candidate for promising applications in the field of semiconductor spintronics. PMID:28809330

Quantum-confined Stark effect at 1.3 μm in Ge/Si(0.35)Ge(0.65) quantum-well structure.

PubMed

Rouifed, Mohamed Said; Chaisakul, Papichaya; Marris-Morini, Delphine; Frigerio, Jacopo; Isella, Giovanni; Chrastina, Daniel; Edmond, Samson; Le Roux, Xavier; Coudevylle, Jean-René; Vivien, Laurent

2012-10-01

Room-temperature quantum-confined Stark effect in a Ge/SiGe quantum-well structure is reported at the wavelength of 1.3 μm. The operating wavelength is tuned by the use of strain engineering. Low-energy plasma-enhanced chemical vapor deposition is used to grow 20 periods of strain-compensated quantum wells (8 nm Ge well and 12 nm Si(0.35)Ge(0.65) barrier) on Si(0.21)Ge(0.79) virtual substrate. The fraction of light absorbed per well allows for a strong modulation around 1.3 μm. The half-width at half-maximum of the excitonic peak of only 12 meV allows for a discussion on physical mechanisms limiting the performances of such devices.

Alleviation of Fermi level pinning at metal/n-Ge interface with lattice-matched Si x Ge1‑ x ‑ y Sn y ternary alloy interlayer on Ge

NASA Astrophysics Data System (ADS)

Suzuki, Akihiro; Nakatsuka, Osamu; Sakashita, Mitsuo; Zaima, Shigeaki

2018-06-01

The impact of a silicon germanium tin (Si x Ge1‑ x ‑ y Sn y ) ternary alloy interlayer on the Schottky barrier height (SBH) of metal/Ge contacts with various metal work functions has been investigated. Lattice matching at the Si x Ge1‑ x ‑ y Sn y /Ge heterointerface is a key factor for controlling Fermi level pinning (FLP) at the metal/Ge interface. The Si x Ge1‑ x ‑ y Sn y ternary alloy interlayer having a small lattice mismatch with the Ge substrate can alleviate FLP at the metal/Ge interface significantly. A Si0.11Ge0.86Sn0.03 interlayer increases the slope parameter for the work function dependence of the SBH to 0.4. An ohmic behavior with an SBH below 0.15 eV can be obtained with Zr and Al/Si0.11Ge0.86Sn0.03/n-Ge contacts at room temperature.

Performance, defect behavior and carrier enhancement in low energy, proton irradiated p+nn+ InP solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

1994-01-01

The highest AMO efficiency (19.1 percent) InP solar cell consisted of an n+pp+ structure epitaxially grown on a p+ InP substrate. However, the high cost and relative fragility of InP served as motivation for research efforts directed at heteroepitaxial growth of InP on more viable substrates. The highest AMO efficiency (13.7 percent) for this type of cell was achieved using a GaAs substrate. Considering only cost and fracture toughness, Si would be the preferred substrate. The fact that Si is a donor in InP introduces complexities which are necessary in order to avoid the formation of an efficiency limiting counterdiode. One method used to overcome this problem lies in employing an n+p+ tunnel junction in contact with the cell's p region. A simpler method consists of using an n+ substrate and processing the cell in the p+ nn+ configuration. This eliminates the need for a tunnel junction. Unfortunately, the p/n configuration has received relatively little attention the best cell with this geometry having achieved an efficiency of 17 percent. Irradiation of these homoepitaxial cells, with 1 Mev electrons, showed that they were slightly more radiation resistant than diffused junction n/p cells. Additional p/n InP cells have been processed by some activity aimed at diffusion. Currently, there has been some activity aimed at producing heteroepitaxial p+nn+ InP cells using n+ Ge substrates. Since, like Si, Ge is an n-dopant in InP, use of this configuration obviates the need for a tunnel junction. Obviously, before attempting to process heteroepitaxial cells, one must produce a reasonably good homoepitaxial cell. In the present case we focus our attention on homoepitaxially on an n+ Ge substrate.

Role of surface energy on the morphology and optical properties of GaP micro & nano structures grown on polar and non-polar substrates

NASA Astrophysics Data System (ADS)

Roychowdhury, R.; Kumar, Shailendra; Wadikar, A.; Mukherjee, C.; Rajiv, K.; Sharma, T. K.; Dixit, V. K.

2017-10-01

Role of surface energy on the morphology, crystalline quality, electronic structure and optical properties of GaP layer grown on Si (001), Si (111), Ge (111) and GaAs (001) is investigated. GaP layers are grown on four different substrates under identical growth kinetics by metal organic vapour phase epitaxy. The atomic force microscopy images show that GaP layer completely covers the surface of GaAs substrate. On the other hand, the surfaces of Si (001), Si (111), Ge (111) substrates are partially covered with crystallographically morphed GaP island type micro and nano-structures. Origin of these crystallographically morphed GaP island is explained by the theoretical calculation of surface energy of the layer and corresponding substrates respectively. The nature of GaP island type micro and nano-structures and layers are single crystalline with existence of rotational twins on Si and Ge (111) substrates which is confirmed by the phi, omega and omega/2theta scans of high resolution x-ray diffraction. The electronic valence band offsets between the GaP and substrates have been determined from the valence band spectra of ultraviolet photoelectron spectroscopy. The valence electron plasmon of GaP are investigated by studying the energy values of Ga (3d) core level along with loss peaks in the energy dependent photoelectron spectra. The peak observed within the range of 3-6 eV from the Ga (3d) core level in the photoelectron spectra are associated to inter band transitions as their energy values are estimated from the pseudo dielectric function by the spectroscopic ellipsometry.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moto, Kenta; Sadoh, Taizoh; Miyao, Masanobu, E-mail: miyao@ed.kyushu-u.ac.jp

Crystalline GeSn-on-insulator structures with high Sn concentration (>8%), which exceeds thermal equilibrium solid-solubility (∼2%) of Sn in Ge, are essential to achieve high-speed thin film transistors and high-efficiency optical devices. We investigate non-thermal equilibrium growth of Ge{sub 1−x}Sn{sub x} (0 ≤ x ≤ 0.2) on quartz substrates by using pulsed laser annealing (PLA). The window of laser fluence enabling complete crystallization without film ablation is drastically expanded (∼5 times) by Sn doping above 5% into Ge. Substitutional Sn concentration in grown layers is found to be increased with decreasing irradiation pulse number. This phenomenon can be explained on the basis of significant thermal non-equilibriummore » growth achieved by higher cooling rate after PLA with a lower pulse number. As a result, GeSn crystals with substitutional Sn concentration of ∼12% are realized at pulse irradiation of single shot for the samples with the initial Sn concentration of 15%. Raman spectroscopy and electron microscopy measurements reveal the high quality of the grown layer. This technique will be useful to fabricate high-speed thin film transistors and high-efficiency optical devices on insulating substrates.« less

High-efficiency thin-film GaAs solar cells, phase2

NASA Technical Reports Server (NTRS)

Yeh, Y. C. M.

1981-01-01

Thin GaAs epi-layers with good crystallographic quality were grown using a (100) Si-substrate on which a thin Ge epi-interlayer was grown by CVD from germane. Both antireflection-coated metal oxide semiconductor (AMOS) and n(+)/p homojunction structures were studied. The AMOS cells were fabricated on undoped-GaAs epi-layers deposited on bulk poly-Ge substrates using organo-metallic CVD film-growth, with the best achieved AM1 conversion efficiency being 9.1%. Both p-type and n(+)-type GaAs growth were optimized using 50 ppm dimethyl zinc and 1% hydrogen sulfide, respectively. A direct GaAs deposition method in fabricating ultra-thin top layer, epitaxial n(+)/p shallow homojunction solar cells on (100) GaAs substrates (without anodic thinning) was developed to produce large area (1 sq/cm) cells, with 19.4% AM1 conversion efficiency achieved. Additionally, an AM1 conversion efficiency of 18.4% (17.5% with 5% grid coverage) was achieved for a single crystal GaAs n(+)/p cell grown by OM-CVD on a Ge wafer.

76 FR 14437 - Economic Simplified Boiling Water Reactor Standard Design: GE Hitachi Nuclear Energy; Issuance of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-16

... NUCLEAR REGULATORY COMMISSION [NRC-2011-0055] Economic Simplified Boiling Water Reactor Standard Design: GE Hitachi Nuclear Energy; Issuance of Final Design Approval The U.S. Nuclear Regulatory Commission has issued a final design approval (FDA) to GE Hitachi Nuclear Energy (GEH) for the economic...

Antiphase boundaries on low-energy-ion bombarded Ge(001)

NASA Astrophysics Data System (ADS)

Zandvliet, H. J. W.; de Groot, E.

1997-01-01

Surface vacancy and adatom clusters have been created on Ge(001) by bombarding the surface with 800 eV argon ions at various substrate temperatures ranging from room temperature to 600 K. The vacancies preferentially annihilate at the ends rather than at the sides of the dimer rows, resulting in monolayer deep vacancy islands which are elongated in a direction of the dimer rows of the upper terrace. As vacancy islands nucleate and expand, the dimer rows in neighbouring vacancy islands need not, in general, align with each other. An antiphase boundary will develop if two growing vacancy islands meet, but their internal dimer rows are not in the same registry. In contrast to Si(001), where only one type of antiphase boundary is found, we have found three different types of antiphase boundaries on Ge(001). Higher dose (> several monolayers) room temperature ion bombardment followed by annealing at temperatures in the range 400-500 K results in a surface which contains a high density of valleys. In addition to the preference for the annihilation of dimer vacancies at descending versus ascending steps we also suggest that the development of antiphase boundaries drives the roughening of this surface. Finally, several atomic rearrangement events, which might be induced by the tunneling process, are observed after low-dose ion bombardment at room temperature.

Determination of the rate of crystal growth from the gas phase under conditions of turbulent free convection

NASA Astrophysics Data System (ADS)

Alad'Ev, S. I.

1987-04-01

Crystal growth in vertical and horizontal cylindrical vials, with the substrate and the source serving as the vial ends, is investigated analytically, assuming that the medium consists of a binary mixture of an active and an inert gas. The active gas is made up of the gaseous products of reactions taking place at the substrate and at the source. It is shown that turbulent free convection leads to an increase in crystal growth rate. All other conditions being equal, crystal growth in vertical vials is greater than that in horizontal ones; in both cases crystal growth rate increases with the vial radius, temperature gradient in the gas phase, and gas phase density. The results are compared with experimental data on the growth of Ge crystals in the Ge-GeI4 system.

Control of interfacial properties of Pr-oxide/Ge gate stack structure by introduction of nitrogen

NASA Astrophysics Data System (ADS)

Kato, Kimihiko; Kondo, Hiroki; Sakashita, Mitsuo; Nakatsuka, Osamu; Zaima, Shigeaki

2011-06-01

We have demonstrated the control of interfacial properties of Pr-oxide/Ge gate stack structure by the introduction of nitrogen. From C- V characteristics of Al/Pr-oxide/Ge 3N 4/Ge MOS capacitors, the interface state density decreases without the change of the accumulation capacitance after annealing. The TEM and TED measurements reveal that the crystallization of Pr-oxide is enhanced with annealing and the columnar structure of cubic-Pr 2O 3 is formed after annealing. From the depth profiles measured using XPS with Ar sputtering for the Pr-oxide/Ge 3N 4/Ge stack structure, the increase in the Ge component is not observed in a Pr-oxide film and near the interface between a Pr-oxide film and a Ge substrate. In addition, the N component segregates near the interface region, amorphous Pr-oxynitride (PrON) is formed at the interface. As a result, Pr-oxide/PrON/Ge stacked structure without the Ge-oxynitride interlayer is formed.

Fabrication of Ta2O5/GeNx gate insulator stack for Ge metal-insulator-semiconductor structures by electron-cyclotron-resonance plasma nitridation and sputtering deposition techniques

NASA Astrophysics Data System (ADS)

Otani, Yohei; Itayama, Yasuhiro; Tanaka, Takuo; Fukuda, Yukio; Toyota, Hiroshi; Ono, Toshiro; Mitsui, Minoru; Nakagawa, Kiyokazu

2007-04-01

The authors have fabricated germanium (Ge) metal-insulator-semiconductor (MIS) structures with a 7-nm-thick tantalum pentaoxide (Ta2O5)/2-nm-thick germanium nitride (GeNx) gate insulator stack by electron-cyclotron-resonance plasma nitridation and sputtering deposition. They found that pure GeNx ultrathin layers can be formed by the direct plasma nitridation of the Ge surface without substrate heating. X-ray photoelectron spectroscopy revealed no oxidation of the GeNx layer after the Ta2O5 sputtering deposition. The fabricated MIS capacitor with a capacitance equivalent thickness of 4.3nm showed excellent leakage current characteristics. The interface trap density obtained by the modified conductance method was 4×1011cm-2eV-1 at the midgap.

Room Temperature Ferromagnetic, Anisotropic, Germanium Rich FeGe(001) Alloys.

PubMed

Lungu, George A; Apostol, Nicoleta G; Stoflea, Laura E; Costescu, Ruxandra M; Popescu, Dana G; Teodorescu, Cristian M

2013-02-21

Ferromagnetic Fe x Ge 1- x with x = 2%-9% are obtained by Fe deposition onto Ge(001) at high temperatures (500 °C). Low energy electron diffraction (LEED) investigation evidenced the preservation of the (1 × 1) surface structure of Ge(001) with Fe deposition. X-ray photoelectron spectroscopy (XPS) at Ge 3d and Fe 2p core levels evidenced strong Fe diffusion into the Ge substrate and formation of Ge-rich compounds, from FeGe₃ to approximately FeGe₂, depending on the amount of Fe deposited. Room temperature magneto-optical Kerr effect (MOKE) evidenced ferromagnetic ordering at room temperature, with about 0.1 Bohr magnetons per Fe atom, and also a clear uniaxial magnetic anisotropy with the in-plane easy magnetization axis. This compound is a good candidate for promising applications in the field of semiconductor spintronics.

Large grain growth of Ge-rich Ge1-xSnx (x ≈ 0.02) on insulating surfaces using pulsed laser annealing in flowing water

NASA Astrophysics Data System (ADS)

Kurosawa, Masashi; Taoka, Noriyuki; Ikenoue, Hiroshi; Nakatsuka, Osamu; Zaima, Shigeaki

2014-02-01

We investigate Sn incorporation effects on the growth characteristics of Ge-rich Ge1-xSnx (x < 0.02) on SiO2 crystallized by pulsed laser annealing (PLA) in air and water. Despite the very low Sn content of 2%, Sn atoms within the GeSn layers play a role in preventing ablation and aggregation of the layers during these PLA. Raman and electron backscatter diffraction measurements demonstrate achievement of large-grain (˜800 nmϕ) growth of Ge0.98Sn0.02 polycrystals by using PLA in water. These polycrystals also show a tensile-strain of ˜0.68%. This result opens up the possibility for developing GeSn-based devices fabricated on flexible substrates as well as Si platforms.

One-dimensional ordering of Ge nanoclusters along atomically straight steps of Si(111)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sekiguchi, Takeharu; Yoshida, Shunji; Itoh, Kohei M.

2007-01-01

Ge nanostructures grown by molecular beam epitaxy on a vicinal Si(111) surface with atomically well-defined steps are studied by means of scanning tunneling microscopy and spectroscopy. When the substrate temperature during deposition is around 250 degree sign C, Ge nanoclusters of diameters less than 2.0 nm form a one-dimensional array of the periodicity 2.7 nm along each step. This self-organization is due to preferential nucleation of Ge on the unfaulted 7x7 half-unit cells at the upper step edges. Scanning tunneling spectroscopy reveals localized electronic states of the nanoclusters.

Band bending at magnetic Ni/Ge(001) interface investigated by X-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Bocîrnea, Amelia Elena; Tănase, Liviu Cristian; Costescu, Ruxandra Maria; Apostol, Nicoleta Georgiana; Teodorescu, Cristian Mihail

2017-12-01

We report the molecular beam epitaxy growth of Ni on a clean Ge(001) surface with an intermediate NiGe layer forming at the interface at room temperature. The crystallinity of the substrate is lost after the deposition of more than 2 Ni monolayers. The Schottky barrier formation is investigated by X-ray photoelectron spectroscopy. The method allows us to infer a 0.39-0.45 eV band bending at the interface between the compound and Ge(001). Magneto-optical Kerr effect measurements were conclusive in detecting the ferromagnetic ordering of Ni outermost layers.

One-step aluminium-assisted crystallization of Ge epitaxy on Si by magnetron sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Ziheng, E-mail: ziheng.liu@unsw.edu.au; Hao, Xiaojing; Ho-Baillie, Anita

In this work, one-step aluminium-assisted crystallization of Ge on Si is achieved via magnetron sputtering by applying an in-situ low temperature (50 °C to 150 °C) heat treatment in between Al and Ge depositions. The effect of heat treatment on film properties and the growth mechanism of Ge epitaxy on Si are studied via X-ray diffraction, Raman and transmission electron microscopy analyses. Compared with the conventional two-step process, the one-step aluminium-assisted crystallization requires much lower thermal budget and results in pure Ge epitaxial layer, which may be suitable for use as a virtual substrate for the fabrication of III-V solar cells.

Ge{sub 1-y}Sn{sub y} (y = 0.01-0.10) alloys on Ge-buffered Si: Synthesis, microstructure, and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Senaratne, C. L.; Kouvetakis, J.; Gallagher, J. D.

Novel hydride chemistries are employed to deposit light-emitting Ge{sub 1-y}Sn{sub y} alloys with y ≤ 0.1 by Ultra-High Vacuum Chemical Vapor Deposition (UHV-CVD) on Ge-buffered Si wafers. The properties of the resultant materials are systematically compared with similar alloys grown directly on Si wafers. The fundamental difference between the two systems is a fivefold (and higher) decrease in lattice mismatch between film and virtual substrate, allowing direct integration of bulk-like crystals with planar surfaces and relatively low dislocation densities. For y ≤ 0.06, the CVD precursors used were digermane Ge₂H₆ and deuterated stannane SnD₄. For y ≥ 0.06, the Gemore » precursor was changed to trigermane Ge₃H₈, whose higher reactivity enabled the fabrication of supersaturated samples with the target film parameters. In all cases, the Ge wafers were produced using tetragermane Ge₄H₁₀ as the Ge source. The photoluminescence intensity from Ge{sub 1–y}Sn{sub y}/Ge films is expected to increase relative to Ge{sub 1–y}Sn{sub y}/Si due to the less defected interface with the virtual substrate. However, while Ge{sub 1–y}Sn{sub y}/Si films are largely relaxed, a significant amount of compressive strain may be present in the Ge{sub 1–y}Sn{sub y}/Ge case. This compressive strain can reduce the emission intensity by increasing the separation between the direct and indirect edges. In this context, it is shown here that the proposed CVD approach to Ge{sub 1–y}Sn{sub y}/Ge makes it possible to approach film thicknesses of about 1 μm, for which the strain is mostly relaxed and the photoluminescence intensity increases by one order of magnitude relative to Ge{sub 1–y}Sn{sub y}/Si films. The observed strain relaxation is shown to be consistent with predictions from strain-relaxation models first developed for the Si{sub 1–x}Ge{sub x}/Si system. The defect structure and atomic distributions in the films are studied in detail using advanced electron-microscopy techniques, including aberration corrected STEM imaging and EELS mapping of the average diamond–cubic lattice.« less

Organometallic chemical vapor deposition and characterization of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates

NASA Technical Reports Server (NTRS)

Xing, G. C.; Bachmann, K. J.; Posthill, J. B.; Timmons, M. L.

1991-01-01

In this paper, we report the epitaxial growth of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates by open tube OMCVD. The chemical composition of the alloys characterized by energy dispersive X-ray spectroscopy shows that alloys with x up to 0.13 can be deposited on (001) GaP. Epitaxial growth with mirror smooth surface morphology has been achieved for x less than or equals to 0.05. Selected area electron diffraction pattern of the alloy shows that the epitaxial layer crystallizes in the chalcopyrite structure with relatively weak superlattice reflections indicating certain degree of randomness in the cation sublattice. Hall measurements show that the alloys are p-type, like the unalloyed films; the carrier concentration, however, dropped about 10 times from 2 x 10 exp 18 to 2 x 10 exp 17/cu cm. Absorption measurements indicate that the band tailing in the absorption spectra of the alloy has been shifted about 0.04 eV towards shorter wavelength as compared to the unalloyed material.

Design of Strain-Engineered GeSn/GeSiSn Quantum Dots for Mid-IR Direct Bandgap Emission on Si Substrate

NASA Astrophysics Data System (ADS)

Al-Saigh, Reem; Baira, Mourad; Salem, Bassem; Ilahi, Bouraoui

2018-06-01

Strain-engineered self-assembled GeSn/GeSiSn quantum dots in Ge matrix have been numerically investigated aiming to study their potentiality towards direct bandgap emission in the mid-IR range. The use of GeSiSn alloy as surrounding media for GeSn quantum dots (QD) allows adjusting the strain around the QD through the variation of Si and/or Sn composition. Accordingly, the lattice mismatch between the GeSn quantum dots and the GeSiSn surrounding layer has been tuned between - 2.3 and - 4.5% through the variation of the Sn barrier composition for different dome-shaped QD sizes. The obtained results show that the emission wavelength, fulfilling the specific QD directness criteria, can be successively tuned over a broad mid-IR range from 3 up to7 μm opening new perspectives for group IV laser sources fully integrated in Si photonic systems for sensing applications.

Structural and chemical ordering of Heusler Co xMn yGe z epitaxial films on Ge (111). Quantitative study using traditional and anomalous x-ray diffraction techniques

DOE PAGES

Collins, B. A.; Chu, Y.; He, L.; ...

2015-12-14

We found that epitaxial films of Co xMn yGe z grown on Ge (111) substrates by molecular-beam-epitaxy techniques have been investigated as a continuous function of composition using combinatorial synchrotron x-ray diffraction (XRD) and x-ray fluorescence (XRF) spectroscopy techniques. A high-resolution ternary epitaxial phase diagram is obtained, revealing a small number of structural phases stabilized over large compositional regions. Ordering of the constituent elements in the compositional region near the full Heusler alloy Co 2MnGe has been examined in detail using both traditional XRD and a new multiple-edge anomalous diffraction (MEAD) technique. Multiple-edge anomalous diffraction involves analyzing the energy dependencemore » of multiple reflections across each constituent absorption edge in order to detect and quantify the elemental distribution of occupation in specific lattice sites. Results of this paper show that structural and chemical ordering are very sensitive to the Co : Mn atomic ratio, such that the ordering is the highest at an atomic ratio of 2 but significantly reduced even a few percent off this ratio. The in-plane lattice is nearly coherent with that of the Ge substrate, while the approximately 2% lattice mismatch is accommodated by the out-of-plane tetragonal strain. Furthermore, the quantitative MEAD analysis reveals no detectable amount (<0.5%) of Co-Mn site swapping, but instead high levels (26%) of Mn-Ge site swapping. Increasing Ge concentration above the Heusler stoichiometry (Co 0.5 Mn 0.25 Ge 0.25 ) is shown to correlate with increased lattice vacancies, antisites, and stacking faults, but reduced lattice relaxation. The highest degree of chemical ordering is observed off the Heusler stoichiometry with a Ge enrichment of 5 at.%.« less

Alternate electrode materials for the SP100 reactor

NASA Astrophysics Data System (ADS)

Randich, E.

1992-05-01

This work was performed in response to a request by the Astro-Space Division of the General Electric Co. to develop alternate electrodes materials for the electrodes of the PD2 modules to be used in the SP100 thermoelectric power conversion system. Initially, the project consisted of four tasks: (1) development of a ZrB2 (C) CVD coating on SiMo substrates; (2) development of a ZrB2 (C) CVD coating on SiGe substrates; (3) development of CVI W for porous graphite electrodes; and (4) technology transfer of pertinent developed processes. The project evolved initially into developing only ZrB2 coatings on SiGe and graphite substrates, and later into developing ZrB2 coatings only on graphite substrates. Several sizes of graphite and pyrolytic carbon-coated graphite substrates were coated with ZrB2 during the project. For budgetary reasons, the project was terminated after half the allotted time had passed. Apart from the production of coated specimens for evaluation, the major accomplishment of the project was the development of the CVD processing to produce the desired coatings.

Structural and chemical ordering of Heusler C o x M n y G e z epitaxial films on Ge (111): Quantitative study using traditional and anomalous x-ray diffraction techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, B. A.; Chu, Y. S.; He, L.

2015-12-01

Epitaxial films of CoxMnyGez grown on Ge (111) substrates by molecular-beam-epitaxy techniques have been investigated as a continuous function of composition using combinatorial synchrotron x-ray diffraction (XRD) and x-ray fluorescence (XRF) spectroscopy techniques. A high-resolution ternary epitaxial phase diagram is obtained, revealing a small number of structural phases stabilized over large compositional regions. Ordering of the constituent elements in the compositional region near the full Heusler alloy Co2MnGe has been examined in detail using both traditional XRD and a new multiple-edge anomalous diffraction (MEAD) technique. Multiple-edge anomalous diffraction involves analyzing the energy dependence of multiple reflections across each constituent absorptionmore » edge in order to detect and quantify the elemental distribution of occupation in specific lattice sites. Results of this paper show that structural and chemical ordering are very sensitive to the Co : Mn atomic ratio, such that the ordering is the highest at an atomic ratio of 2 but significantly reduced even a few percent off this ratio. The in-plane lattice is nearly coherent with that of the Ge substrate, while the approximately 2% lattice mismatch is accommodated by the out-of-plane tetragonal strain. The quantitative MEAD analysis further reveals no detectable amount (< 0.5%) of Co-Mn site swapping, but instead high levels (26%) of Mn-Ge site swapping. Increasing Ge concentration above the Heusler stoichiometry (Co0.5Mn0.25Ge0.25) is shown to correlate with increased lattice vacancies, antisites, and stacking faults, but reduced lattice relaxation. The highest degree of chemical ordering is observed off the Heusler stoichiometry with a Ge enrichment of 5 at.%.« less

Metal-Free CVD Graphene Synthesis on 200 mm Ge/Si(001) Substrates.

PubMed

Lukosius, M; Dabrowski, J; Kitzmann, J; Fursenko, O; Akhtar, F; Lisker, M; Lippert, G; Schulze, S; Yamamoto, Y; Schubert, M A; Krause, H M; Wolff, A; Mai, A; Schroeder, T; Lupina, G

2016-12-14

Good quality, complementary-metal-oxide-semiconductor (CMOS) technology compatible, 200 mm graphene was obtained on Ge(001)/Si(001) wafers in this work. Chemical vapor depositions were carried out at the deposition temperatures of 885 °C using CH 4 as carbon source on epitaxial Ge(100) layers, which were grown on Si(100), prior to the graphene synthesis. Graphene layer with the 2D/G ratio ∼3 and low D mode (i.e., low concentration of defects) was measured over the entire 200 mm wafer by Raman spectroscopy. A typical full-width-at-half-maximum value of 39 cm -1 was extracted for the 2D mode, further indicating that graphene of good structural quality was produced. The study also revealed that the lack of interfacial oxide correlates with superior properties of graphene. In order to evaluate electrical properties of graphene, its 2 × 2 cm 2 pieces were transferred onto SiO 2 /Si substrates from Ge/Si wafers. The extracted sheet resistance and mobility values of transferred graphene layers were ∼1500 ± 100 Ω/sq and μ ≈ 400 ± 20 cm 2 /V s, respectively. The transferred graphene was free of metallic contaminations or mechanical damage. On the basis of results of DFT calculations, we attribute the high structural quality of graphene grown by CVD on Ge to hydrogen-induced reduction of nucleation probability, explain the appearance of graphene-induced facets on Ge(001) as a kinetic effect caused by surface step pinning at linear graphene nuclei, and clarify the orientation of graphene domains on Ge(001) as resulting from good lattice matching between Ge(001) and graphene nucleated on such nuclei.

Heavy Ion Current Transients in SiGe HBTs

NASA Technical Reports Server (NTRS)

Pellish, Jonathan A.; Reed, Robert A.; Vizkelethy, Gyorgy; McMorrow, Dale; Ferlet-Cavrois, Veronique; Baggio, Jacques; Paillet, Philipe; Duhanel, Olivier; Phillips, Stanley D.; Sutton, Akil K.;

Structural and thermochemical Aspects of (III-V)IV3 Material Assembly from First Principles

NASA Astrophysics Data System (ADS)

Chizmeshya, Andrew; Kouvetakis, John

2014-03-01

Alloys with (III-V)-(IV) compositions, including Si3(AlP), Si5-2y(AlP)y, Si3Al(As1-xNx), Si5-2yAl(P1-xNx)y and Ge5-2y(InP)y and have recently been synthesized as mono-crystalline films on Si substrates, using a synthesis route specifically designed to avoid phase separation between the III-V and IV constituents. Molecular ``building blocks'' containing group-V-centered III-V-IV3 cores, formed via interactions of group-III atoms and reactive silyly/germyl hydride precursors of desired composition (e.g, P(SiH3)3 , P(GeH3)3 , etc), assemble to form stable, covalent, diamond-like materials with the inherent tetrahedral symmetry and composition of the III-V-IV3 units. The resulting systems may provide access to a broad range of new semiconductor systems with extended optoelectronic properties, provided that the required molecular sources are available, the thermodynamic processes are viable, and the resulting alloy composition can be tuned to lattice-match the growth substrate. Molecular/solid-state simulations are used to identify promising synthetic pathways and guide the epitaxial creation of new (III-V)-(IV) materials. The thermodynamics of gas phase synthesis reactions, energetic stability of the alloys, and their epitaxial/chemical compatibility with the substrate are combined to form a global figure of merit. The latter corroborates the synthesis of known systems and predicts that formation of GaPSi3/Si(100), GaAsSi3/SiGe(100), AlPGe3/Ge(100) and InAsSi3/Ge(100) may also be favorable. Supported by NSF-DMR under SusChEM award #1309090.

Structural and electrical properties of Ge-on-Si(0 0 1) layers with ultra heavy n-type doping grown by MBE

NASA Astrophysics Data System (ADS)

Yurasov, D. V.; Antonov, A. V.; Drozdov, M. N.; Yunin, P. A.; Andreev, B. A.; Bushuykin, P. A.; Baydakova, N. A.; Novikov, A. V.

2018-06-01

In this paper we report about the formation of ultra heavy doped n-Ge layers on Si(0 0 1) substrates by molecular beam epitaxy and their characterization by different independent techniques. Combined study of structural and electrical properties of fabricated layers using secondary ion mass spectroscopy, X-ray diffraction, Hall effect and reflection measurements was carried out and it has revealed the achievable charge carrier densities exceeding 1020 cm-3 without deterioration of crystalline quality of such doped layers. It was also shown that X-ray analysis can be used as a fast, reliable and non-destructive method for evaluation of the electrically active Sb concentration in heavy doped Ge layers. The appropriate set of doping density allowed to adjust the plasmonic resonance position in Ge:Sb layers in a rather wide range reaching the wavelength of 3.6 μm for the highest doping concentration. Room temperature photoluminescence confirmed the high crystalline quality of such doped layers. Our results indicated the attainability of high electron concentration in Ge:Sb layers grown on Si substrates without crystalline quality deterioration which may find potential applications in the fields of Si-based photonics and mid-IR plasmonics.

Low-temperature photoluminescence study of thin epitaxial GaAs films on Ge substrates

NASA Astrophysics Data System (ADS)

Brammertz, Guy; Mols, Yves; Degroote, Stefan; Motsnyi, Vasyl; Leys, Maarten; Borghs, Gustaaf; Caymax, Matty

2006-05-01

Thin epitaxial GaAs films, with thickness varying from 140 to 1000 nm and different Si doping levels, were grown at 650 °C by organometallic vapor phase epitaxy on Ge substrates and analyzed by low-temperature photoluminescence (PL) spectroscopy. All spectra of thin GaAs on Ge show two different structures, one narrow band-to-band (B2B) structure at an energy of ~1.5 eV and a broad inner-band-gap (IB) structure at an energy of ~1.1 eV. Small strain in the thin GaAs films causes the B2B structure to be separated into a light-hole and a heavy-hole peak. At 2.5 K the good structural quality of the thin GaAs films on Ge can be observed from the narrow excitonic peaks. Peak widths of less than 1 meV are measured. GaAs films with thickness smaller than 200 nm show B2B PL spectra with characteristics of an n-type doping level of approximately 1018 at./cm3. This is caused by heavy Ge diffusion from the substrate into the GaAs at the heterointerface between the two materials. The IB structure observed in all films consists of two Gaussian peaks with energies of 1.04 and 1.17 eV. These deep trapping states arise from Ge-based complexes formed within the GaAs at the Ge-GaAs heterointerface, due to strong diffusion of Ge atoms into the GaAs. Because of similarities with Si-based complexes, the peak at 1.04 eV was identified to be due to a GeGa-GeAs complex, whereas the peak at 1.17 eV was attributed to the GeGa-VGa complex. The intensity of the IB structure decreases strongly as the GaAs film thickness is increased. PL intensity of undoped GaAs films containing antiphase domains (APDs) is four orders of magnitude lower than for similar films without APDs. This reduction in intensity is due to the electrically active Ga-Ga and As-As bonds at the boundaries between the different APDs. When the Si doping level is increased, the PL intensity of the APD-containing films is increased again as well. A film containing APDs with a Si doping level of ~1018 at./cm3 has only a factor 10 reduced intensity. We tentatively explain this observation by Si or Ge clustering at antiphase boundaries, which eliminates the effects of the Ga-Ga and As-As bonds. This assumption is confirmed by the fact that, at 77 K, the ratio between the intensity of the IB peak at 1.17 eV to the intensity of the peak at 1.04 eV is smaller than 1.4 for all films containing APDs, whereas it is larger than 1.4 for all films without APDs. This shows stronger clustering of Si or Ge in the material with APDs. For future electronic applications, Ge diffusion into the GaAs will have to be reduced. PL analysis will be a rapid tool for studying the Ge diffusion into the GaAs thin films.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponath, Patrick; O’Hara, Andrew; Cao, Hai-Xia

The growth of Co-substituted BaTiO 3 (BTO) films on Ge(001) substrates by molecular beam epitaxy is demonstrated in this paper. Energy-dispersive x-ray spectroscopy and transmission electron microscopy images confirm the uniform Co distribution. However, no evidence of magnetic ordering is observed in samples grown for Co concentrations between 2% and 40%. Piezoresponse force microscopy measurements show that a 5% Co-substituted BTO sample exhibits ferroelectric behavior. First-principles calculations indicate that while Co atoms couple ferromagnetically in the absence of oxygen vacancies, the occurrence of oxygen vacancies leads to locally antiferromagnetically coupled complexes with relatively strong spin coupling. Finally, the presence ofmore » a significant amount of oxygen vacancies is suggested by x-ray photoelectron spectroscopy measurements.« less

Vapor-solid-solid grown Ge nanowires at integrated circuit compatible temperature by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Zhu, Zhongyunshen; Song, Yuxin; Zhang, Zhenpu; Sun, Hao; Han, Yi; Li, Yaoyao; Zhang, Liyao; Xue, Zhongying; Di, Zengfeng; Wang, Shumin

2017-09-01

We demonstrate Au-assisted vapor-solid-solid (VSS) growth of Ge nanowires (NWs) by molecular beam epitaxy at the substrate temperature of ˜180 °C, which is compatible with the temperature window for Si-based integrated circuit. Low temperature grown Ge NWs hold a smaller size, similar uniformity, and better fit with Au tips in diameter, in contrast to Ge NWs grown at around or above the eutectic temperature of Au-Ge alloy in the vapor-liquid-solid (VLS) growth. Six ⟨110⟩ growth orientations were observed on Ge (110) by the VSS growth at ˜180 °C, differing from only one vertical growth direction of Ge NWs by the VLS growth at a high temperature. The evolution of NWs dimension and morphology from the VLS growth to the VSS growth is qualitatively explained by analyzing the mechanism of the two growth modes.

Segregation of Sb in Ge epitaxial layers and its usage for the selective doping of Ge-based structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antonov, A. V.; Drozdov, M. N.; Novikov, A. V., E-mail: anov@ipmras.ru

2015-11-15

The segregation of Sb in Ge epitaxial layers grown by the method of molecular beam epitaxy on Ge (001) substrates is investigated. For a growth temperature range of 180–325°C, the temperature dependence is determined for the segregation ratio of Sb in Ge, which shows a sharp increase (by more than three orders of magnitude) with increasing temperature. The strong dependence of the segregation properties of Sb on the growth temperature makes it possible to adapt a method based on the controlled use of segregation developed previously for the doping of Si structures for the selective doping of Ge structures withmore » a donor impurity. Using this method selectively doped Ge:Sb structures, in which the bulk impurity concentration varies by an order of magnitude at distances of 3–5 nm, are obtained.« less

Wet cleaning and surface characterization of Si 1- xGe x virtual substrates after a CMP step

NASA Astrophysics Data System (ADS)

Abbadie, A.; Hartmann, J. M.; Besson, P.; Rouchon, D.; Martinez, E.; Holliger, P.; Di Nardo, C.; Campidelli, Y.; Billon, T.

2008-08-01

New reactants such as ozone dissolved in ultra-pure water have been widely used the last few years instead of the original Radio Corporation of America (RCA) cleaning (which is a combination of the Standard Cleaning 1 (SC1) and the Standard Cleaning 2 (SC2)). In a first part of the study (Microelectron. Eng. 83 (2006) 1986), we had quantified the efficiency of a new cleaning sequence (that calls upon HF and H 2O/O 3 solutions) on polished Si 1- xGe x virtual substrates ( x = 0.2-0.5). We are discussing here the surface morphology and wetability together with the oxide thickness and structure typically obtained after this so-called "DDC-SiGe" wet cleaning. Flat surface morphologies are found after cleaning whatever the Ge content (from 20 to 50%). Typical root mean square roughness is around 0.4 nm. We have used X-ray Photoelectron Spectroscopy to determine the characteristics of the surface termination after this "DDC-SiGe" cleaning. An oxide mainly composed of SiO 2 is formed, with a low fraction of Ge sub-oxide and GeO 2. The distribution of chemical species is not that different from the one obtained after the use of a SC1 cleaning. However, the chemical oxide formed is slightly thicker. Such a HF/O 3 cleaning leads, when used on thick Ge layers grown on Si, to the formation of a really thin Ge sub-oxide. Our oxidation model assumes a competition in O 3 solutions between the oxidation rates of Si and Ge atoms (faster for Si) and the dissolution of the Ge oxide formed in solution. This mechanism, which implies the formation of a slightly porous oxide, is different from the one seeming to occur in SC1-based solutions. Indeed, the addition of surfactant in a SC1 solution modifies the oxidation rate compared to standard SC1 or O 3-based solutions, suggesting a diffusion of reactants towards the interface between the SiGe and the oxide in formation, assisted by the reactions of species within the cleaning solutions.

Solar cell circuit and method for manufacturing solar cells

NASA Technical Reports Server (NTRS)

Mardesich, Nick (Inventor)

2010-01-01

The invention is a novel manufacturing method for making multi-junction solar cell circuits that addresses current problems associated with such circuits by allowing the formation of integral diodes in the cells and allows for a large number of circuits to readily be placed on a single silicon wafer substrate. The standard Ge wafer used as the base for multi-junction solar cells is replaced with a thinner layer of Ge or a II-V semiconductor material on a silicon/silicon dioxide substrate. This allows high-voltage cells with multiple multi-junction circuits to be manufactured on a single wafer, resulting in less array assembly mass and simplified power management.

Preparation and performance of broadband antireflective sub-wavelength structures on Ge substrate

NASA Astrophysics Data System (ADS)

Shen, Xiang-Wei; Liu, Zheng-Tang; Li, Yang-Ping; Lu, Hong-Cheng; Xu, Qi-Yuan; Liu, Wen-Ting

2009-01-01

Sub-wavelength structures (SWS) were prepared on Ge substrates through photolithography and reactive ion etching (RIE) technology for broadband antireflective purposes in the long wave infrared (LWIR) waveband of 8-12 μm. Topography of the etched patterns was observed using high resolution optical microscope and atomic force microscope (AFM). Infrared transmission performance of the SWS was investigated by Fourier transform infrared (FTIR) spectrometer. Results show that the etched patterns were of high uniformity and fidelity, the SWS exhibited a good broadband antireflective performance with the increment of the average transmittance which is over 8-12 μm up to 8%.

High Electron Mobility in SiGe/Si n-MODFET Structures on Sapphire Substrates

NASA Technical Reports Server (NTRS)

Mueller, Carl H.; Croke, Edward T.; Alterovitz, Samuel A.

2003-01-01

For the first time, SiGe/Si n-Modulation Doped Field Effect Transistors (n-MODFET) structures have been grown on sapphire substrates. Room temperature electron mobility value of 1271 square centimeters N-sec at an electron carrier density (n(sub e) = 1.33x10(exp 12) per square centimeter)) of 1.6 x 10(exp 12) per square centimeter was obtained. At 250 mK, the mobility increases to 13,313 square centimeters/V-sec (n(sub e)=1.33x10(exp 12) per square centimeter)) and Shubnikov-de Haas oscillations appear, showing excellent confinement of the two-dimensional electron gas.

Low-temperature reduction of Ge oxide by Si and SiH4 in low-pressure H2 and Ar environment

NASA Astrophysics Data System (ADS)

Minami, Kaichiro; Moriya, Atsushi; Yuasa, Kazuhiro; Maeda, Kiyohiko; Yamada, Masayuki; Kunii, Yasuo; Niwano, Michio; Murota, Junichi

2015-08-01

Introduction of Ge into ULSIs has become increasingly attractive because of the higher carrier mobility of Ge. Since Ge native oxide is formed easily in cleanroom air, the control of formation and reduction of the Ge oxide is requested for the introduction of Ge layers into Si process. Here, the reactions between gas phase Ge oxide and Si substrate and between the Ge oxide on Ge epitaxial layer and SiH4 are investigated. The native-oxidized Ge amount is obtained by calculating from chemically shifted peak intensity of Ge 3d measured by X-ray photoelectron spectroscopy. By the adsorption of the Ge oxide on Si(1 0 0) surface, pure Ge and Si oxide are formed on the Si surface even at 350 °C and the formed Ge amount tends to correspond to the oxidized Si amount, independently of the heat-treatment environment of H2 and Ar under the condition that Si oxide is not reduced by H2. By SiH4 treatment, the amount of the oxidized Ge on the Ge layer decreases drastically even at 350 °C and Si oxide is formed on the Ge layer. From these results, it is suggested that the Ge oxide is reduced even at 350 °C by Si or SiH4, and the Si oxide and the pure Ge are formed.

Beneficial defects: exploiting the intrinsic polishing-induced wafer roughness for the catalyst-free growth of Ge in-plane nanowires.

PubMed

Persichetti, Luca; Sgarlata, Anna; Mori, Stefano; Notarianni, Marco; Cherubini, Valeria; Fanfoni, Massimo; Motta, Nunzio; Balzarotti, Adalberto

2014-01-01

We outline a metal-free fabrication route of in-plane Ge nanowires on Ge(001) substrates. By positively exploiting the polishing-induced defects of standard-quality commercial Ge(001) wafers, micrometer-length wires are grown by physical vapor deposition in ultra-high-vacuum environment. The shape of the wires can be tailored by the epitaxial strain induced by subsequent Si deposition, determining a progressive transformation of the wires in SiGe faceted quantum dots. This shape transition is described by finite element simulations of continuous elasticity and gives hints on the equilibrium shape of nanocrystals in the presence of tensile epitaxial strain. 81.07.Gf; 68.35.bg; 68.35.bj; 62.23.Eg.

The Role of Surface Passivation in Controlling Ge Nanowire Faceting.

PubMed

Gamalski, A D; Tersoff, J; Kodambaka, S; Zakharov, D N; Ross, F M; Stach, E A

2015-12-09

In situ transmission electron microscopy observations of nanowire morphologies indicate that during Au-catalyzed Ge nanowire growth, Ge facets can rapidly form along the nanowire sidewalls when the source gas (here, digermane) flux is decreased or the temperature is increased. This sidewall faceting is accompanied by continuous catalyst loss as Au diffuses from the droplet to the wire surface. We suggest that high digermane flux and low temperatures promote effective surface passivation of Ge nanowires with H or other digermane fragments inhibiting diffusion and attachment of Au and Ge on the sidewalls. These results illustrate the essential roles of the precursor gas and substrate temperature in maintaining nanowire sidewall passivation, necessary to ensure the growth of straight, untapered, ⟨111⟩-oriented nanowires.

Phase separation in SiGe nanocrystals embedded in SiO{sub 2} matrix during high temperature annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mogaddam, N. A. P.; Turan, R.; Alagoz, A. S.

2008-12-15

SiGe nanocrystals have been formed in SiO{sub 2} matrix by cosputtering Si, Ge, and SiO{sub 2} independently on Si substrate. Effects of the annealing time and temperature on structural and compositional properties are studied by transmission electron microscopy, x-ray diffraction (XRD), and Raman spectroscopy measurements. It is observed that Ge-rich Si{sub (1-x)}Ge{sub x} nanocrystals do not hold their compositional uniformity when annealed at high temperatures for enough long time. A segregation process leading to separation of Ge and Si atoms from each other takes place. This process has been evidenced by a double peak formation in the XRD and Ramanmore » spectra. We attributed this phase separation to the differences in atomic size, surface energy, and surface diffusion disparity between Si and Ge atoms leading to the formation of nonhomogenous structure consist of a Si-rich SiGe core covered by a Ge-rich SiGe shell. This experimental observation is consistent with the result of reported theoretical and simulation methods.« less

Franz-Keldysh effect in GeSn pin photodetectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oehme, M., E-mail: oehme@iht.uni-stuttgart.de; Kostecki, K.; Schmid, M.

2014-04-21

The optical properties and the Franz-Keldysh effect at the direct band gap of GeSn alloys with Sn concentrations up to 4.2% at room temperature were investigated. The GeSn material was embedded in the intrinsic region of a Ge heterojunction photodetector on Si substrates. The layer structure was grown by means of ultra-low temperature molecular beam epitaxy. The absorption coefficient as function of photon energy and the direct bandgap energies were determined. In all investigated samples, the Franz-Keldysh effect can be observed. A maximum absorption ratio of 1.5 was determined for 2% Sn for a voltage swing of 3 V.

Three-State Quantum Dot Gate FETs Using ZnS-ZnMgS Lattice-Matched Gate Insulator on Silicon

NASA Astrophysics Data System (ADS)

Karmakar, Supriya; Suarez, Ernesto; Jain, Faquir C.

2011-08-01

This paper presents the three-state behavior of quantum dot gate field-effect transistors (FETs). GeO x -cladded Ge quantum dots (QDs) are site-specifically self-assembled over lattice-matched ZnS-ZnMgS high- κ gate insulator layers grown by metalorganic chemical vapor deposition (MOCVD) on silicon substrates. A model of three-state behavior manifested in the transfer characteristics due to the quantum dot gate is also presented. The model is based on the transfer of carriers from the inversion channel to two layers of cladded GeO x -Ge quantum dots.

Search for massive colored scalars in four-jet final states in $$\\sqrt{s}=7~\\mbox{TeV}$$ proton–proton collisions with the ATLAS detector

DOE PAGES

Aad, G.; Abbott, B.; Abdallah, J.; ...

2011-12-17

A search for pair-produced scalar particles decaying to a four-jet final state is presented. The analysis is performed using an integrated luminosity of 34 pb -1 recorded by the ATLAS detector in 2010. No deviation from the Standard Model is observed. For a scalar mass of 100 GeV (190 GeV) the limit on the scalar gluon pair production cross section at 95% confidence level is 1 nb (0.28 nb). When these results are interpreted as mass limits, scalar-gluons (hyperpions) with masses of 100 to 185 GeV (100 to 155 GeV) are excluded at 95% confidence level with the exception ofmore » a mass window of width about 5 GeV (15 GeV) around 140 GeV.« less

Multi-junction, monolithic solar cell using low-band-gap materials lattice matched to GaAs or Ge

DOEpatents

Olson, Jerry M.; Kurtz, Sarah R.; Friedman, Daniel J.

2001-01-01

A multi-junction, monolithic, photovoltaic solar cell device is provided for converting solar radiation to photocurrent and photovoltage with improved efficiency. The solar cell device comprises a plurality of semiconductor cells, i.e., active p/n junctions, connected in tandem and deposited on a substrate fabricated from GaAs or Ge. To increase efficiency, each semiconductor cell is fabricated from a crystalline material with a lattice constant substantially equivalent to the lattice constant of the substrate material. Additionally, the semiconductor cells are selected with appropriate band gaps to efficiently create photovoltage from a larger portion of the solar spectrum. In this regard, one semiconductor cell in each embodiment of the solar cell device has a band gap between that of Ge and GaAs. To achieve desired band gaps and lattice constants, the semiconductor cells may be fabricated from a number of materials including Ge, GaInP, GaAs, GaInAsP, GaInAsN, GaAsGe, BGaInAs, (GaAs)Ge, CuInSSe, CuAsSSe, and GaInAsNP. To further increase efficiency, the thickness of each semiconductor cell is controlled to match the photocurrent generated in each cell. To facilitate photocurrent flow, a plurality of tunnel junctions of low-resistivity material are included between each adjacent semiconductor cell. The conductivity or direction of photocurrent in the solar cell device may be selected by controlling the specific p-type or n-type characteristics for each active junction.

The Effects of Annealing Temperatures on Composition and Strain in SixGe1−x Obtained by Melting Growth of Electrodeposited Ge on Si (100)

PubMed Central

Abidin, Mastura Shafinaz Zainal; Morshed, Tahsin; Chikita, Hironori; Kinoshita, Yuki; Muta, Shunpei; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Matsumura, Ryo; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

2014-01-01

The effects of annealing temperatures on composition and strain in SixGe1−x, obtained by rapid melting growth of electrodeposited Ge on Si (100) substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 and 1100°C for 1 s. All annealed samples show single crystalline structure in (100) orientation. A significant appearance of Si-Ge vibration mode peak at ~00 cm−1 confirms the existence of Si-Ge intermixing due to out-diffusion of Si into Ge region. On a rapid melting process, Ge melts and reaches the thermal equilibrium in short time. Si at Ge/Si interface begins to dissolve once in contact with the molten Ge to produce Si-Ge intermixing. The Si fraction in Si-Ge intermixing was calculated by taking into account the intensity ratio of Ge-Ge and Si-Ge vibration mode peaks and was found to increase with the annealing temperatures. It is found that the strain turns from tensile to compressive as the annealing temperature increases. The Si fraction dependent thermal expansion coefficient of SixGe1−x is a possible cause to generate such strain behavior. The understanding of compositional and strain characteristics is important in Ge/Si heterostructure as these properties seem to give significant effects in device performance. PMID:28788521

The Effects of Annealing Temperatures on Composition and Strain in Si x Ge1-x Obtained by Melting Growth of Electrodeposited Ge on Si (100).

PubMed

Abidin, Mastura Shafinaz Zainal; Morshed, Tahsin; Chikita, Hironori; Kinoshita, Yuki; Muta, Shunpei; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Matsumura, Ryo; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

2014-02-24

The effects of annealing temperatures on composition and strain in Si x Ge 1- x , obtained by rapid melting growth of electrodeposited Ge on Si (100) substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 and 1100 °C for 1 s. All annealed samples show single crystalline structure in (100) orientation. A significant appearance of Si-Ge vibration mode peak at ~400 cm -1 confirms the existence of Si-Ge intermixing due to out-diffusion of Si into Ge region. On a rapid melting process, Ge melts and reaches the thermal equilibrium in short time. Si at Ge/Si interface begins to dissolve once in contact with the molten Ge to produce Si-Ge intermixing. The Si fraction in Si-Ge intermixing was calculated by taking into account the intensity ratio of Ge-Ge and Si-Ge vibration mode peaks and was found to increase with the annealing temperatures. It is found that the strain turns from tensile to compressive as the annealing temperature increases. The Si fraction dependent thermal expansion coefficient of Si x Ge 1- x is a possible cause to generate such strain behavior. The understanding of compositional and strain characteristics is important in Ge/Si heterostructure as these properties seem to give significant effects in device performance.

Plateau-Rayleigh Crystal Growth of Nanowire Heterostructures: Strain-Modified Surface Chemistry and Morphological Control in One, Two, and Three Dimensions.

PubMed

Day, Robert W; Mankin, Max N; Lieber, Charles M

2016-04-13

One-dimensional (1D) structures offer unique opportunities for materials synthesis since crystal phases and morphologies that are difficult or impossible to achieve in macroscopic crystals can be synthesized as 1D nanowires (NWs). Recently, we demonstrated one such phenomenon unique to growth on a 1D substrate, termed Plateau-Rayleigh (P-R) crystal growth, where periodic shells develop along a NW core to form diameter-modulated NW homostructures with tunable morphologies. Here we report a novel extension of the P-R crystal growth concept with the synthesis of heterostructures in which Ge (Si) is deposited on Si (Ge) 1D cores to generate complex NW morphologies in 1, 2, or 3D. Depositing Ge on 50 nm Si cores with a constant GeH4 pressure yields a single set of periodic shells, while sequential variation of GeH4 pressure can yield multimodulated 1D NWs with two distinct sets of shell periodicities. P-R crystal growth on 30 nm cores also produces 2D loop structures, where Ge (Si) shells lie primarily on the outside (inside) of a highly curved Si (Ge) core. Systematic investigation of shell morphology as a function of growth time indicates that Ge shells grow in length along positive curvature Si cores faster than along straight Si cores by an order of magnitude. Short Ge deposition times reveal that shells develop on opposite sides of 50 and 100 nm Si cores to form straight 1D morphologies but that shells develop on the same side of 20 nm cores to produce 2D loop and 3D spring structures. These results suggest that strain mediates the formation of 2 and 3D morphologies by altering the NW's surface chemistry and that surface diffusion of heteroatoms on flexible freestanding 1D substrates can facilitate this strain-mediated mechanism.

Low temperature growth of heavy boron-doped hydrogenated Ge epilayers and its application in Ge/Si photodetectors

NASA Astrophysics Data System (ADS)

Kuo, Wei-Cheng; Lee, Ming Jay; Wu, Mount-Learn; Lee, Chien-Chieh; Tsao, I.-Yu; Chang, Jenq-Yang

2017-04-01

In this study, heavily boron-doped hydrogenated Ge epilayers are grown on Si substrates at a low growth temperature (220 °C). The quality of the boron-doped epilayers is dependent on the hydrogen flow rate. The optical emission spectroscopic, X-ray diffraction and Hall measurement results demonstrate that better quality boron-doped Ge epilayers can be obtained at low hydrogen flow rates (0 sccm). This reduction in quality is due to an excess of hydrogen in the source gas, which breaks one of the Ge-Ge bonds on the Ge surface, leading to the formation of unnecessary dangling bonds. The structure of the boron doped Ge epilayers is analyzed by transmission electron microscopy and atomic force microscopy. In addition, the performance, based on the I-V characteristics, of Ge/Si photodetectors fabricated with boron doped Ge epilayers produced under different hydrogen flow rates was examined. The photodetectors with boron doped Ge epilayers produced with a low hydrogen flow rate (0 sccm) exhibited a higher responsivity of 0.144 A/W and a lower dark current of 5.33 × 10-7 A at a reverse bias of 1 V.

Inspecting the microstructure of electrically active defects at the Ge/GeOx interface

NASA Astrophysics Data System (ADS)

Fanciulli, Marco; Baldovino, Silvia; Molle, Alessandro

2012-02-01

High mobility substrates are important key elements in the development of advanced devices targeting a vast range of functionalities. Among them, Ge showed promising properties promoting it as valid candidate to replace Si in CMOS technology. However, the electrical quality of the Ge/oxide interface is still a problematic issue, in particular for the observed inversion of the n-type Ge surface, attributed to the presence of dangling bonds inducing a severe band bending [1]. In this scenario, the identification of electrically active defects present at the Ge/oxide interface and the capability to passivate or anneal them becomes a mandatory issue aiming at an electrically optimized interface. We report on the application of highly sensitive electrically detected magnetic resonance (EDMR) techniques in the investigation of defects at the interface between Ge and GeO2 (or GeOx), including Ge dangling bonds and defects in the oxide [2]. In particular we will investigate how different surface orientations, e.g. the (001) against the (111) Ge surface, impacts the microstructure of the interface defects. [1] P. Tsipas and A. Dimoulas, Appl. Phys. Lett. 94, 012114 (2009) [2] S. Baldovino, A. Molle, and M. Fanciulli, Appl. Phys. Lett. 96, 222110 (2010)

Morphology and chemical composition of cobalt germanide islands on Ge(001).

PubMed

Ewert, M; Schmidt, Th; Flege, J I; Heidmann, I; Grzela, T; Klesse, W M; Foerster, M; Aballe, L; Schroeder, T; Falta, J

2016-08-12

The reactive growth of cobalt germanide on Ge(001) was investigated by means of in situ x-ray absorption spectroscopy photoemission electron microscopy (XAS-PEEM), micro-illumination low-energy electron diffraction (μ-LEED), and ex situ atomic force microscopy (AFM). At a Co deposition temperature of 670 °C, a rich morphology with different island shapes and dimensions is observed, and a correlation between island morphology and stoichiometry is found. By combining XAS-PEEM and μ-LEED, we were able to identify a large part of the islands to consist of CoGe2, with many of them having an unusual epitaxial relationship: CoGe2 [Formula: see text] [Formula: see text] Ge [Formula: see text]. Side facets with (112) and (113) orientation have been found for such islands. However, two additional phases were observed, most likely Co5Ge7 and CoGe. Comparing growth on Ge(001) single crystals and on Ge(001)/Si(001) epilayer substrates, the occurrence of these intermediate phases seems to be promoted by defects or residual strain.

Engineered unique elastic modes at a BaTiO 3/2x1-Ge(001) interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumah, D. P.; Dogan, M.; Ngai, J. H.

Here, the strong interaction at an interface between a substrate and thin film leads to epitaxy and provides a means of inducing structural changes in the epitaxial film. These induced material phases often exhibit technologically relevant electronic, magnetic, and functional properties. The 2×1 surface of a Ge(001) substrate applies a unique type of epitaxial constraint on thin films of the perovskite oxide BaTiO 3 where a change in bonding and symmetry at the interface leads to a non-bulk-like crystal structure of the BaTiO 3. While the complex crystal structure is predicted using first-principles theory, it is further shown that themore » details of the structure are a consequence of hidden phases found in the bulk elastic response of the BaTiO 3 induced by the symmetry of forces exerted by the germanium substrate.« less

Engineered Unique Elastic Modes at a BaTiO 3 / ( 2 × 1 ) - Ge ( 001 ) Interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumah, D. P.; Dogan, M.; Ngai, J. H.

The strong interaction at an interface between a substrate and thin film leads to epitaxy and provides a means of inducing structural changes in the epitaxial film. These induced material phases often exhibit technologically relevant electronic, magnetic, and functional properties. The 2×1 surface of a Ge(001) substrate applies a unique type of epitaxial constraint on thin films of the perovskite oxide BaTiO3 where a change in bonding and symmetry at the interface leads to a non-bulk-like crystal structure of the BaTiO3. While the complex crystal structure is predicted using first-principles theory, it is further shown that the details of themore » structure are a consequence of hidden phases found in the bulk elastic response of the BaTiO3 induced by the symmetry of forces exerted by the germanium substrate.« less

Engineered unique elastic modes at a BaTiO 3/2x1-Ge(001) interface

DOE PAGES

Kumah, D. P.; Dogan, M.; Ngai, J. H.; ...

2016-03-07

Here, the strong interaction at an interface between a substrate and thin film leads to epitaxy and provides a means of inducing structural changes in the epitaxial film. These induced material phases often exhibit technologically relevant electronic, magnetic, and functional properties. The 2×1 surface of a Ge(001) substrate applies a unique type of epitaxial constraint on thin films of the perovskite oxide BaTiO 3 where a change in bonding and symmetry at the interface leads to a non-bulk-like crystal structure of the BaTiO 3. While the complex crystal structure is predicted using first-principles theory, it is further shown that themore » details of the structure are a consequence of hidden phases found in the bulk elastic response of the BaTiO 3 induced by the symmetry of forces exerted by the germanium substrate.« less

Ge growth on vicinal si(001) surfaces: island's shape and pair interaction versus miscut angle.

PubMed

Persichetti, L; Sgarlata, A; Fanfoni, M; Balzarotti, A

2011-10-01

A complete description of Ge growth on vicinal Si(001) surfaces is provided. The distinctive mechanisms of the epitaxial growth process on vicinal surfaces are clarified from the very early stages of Ge deposition to the nucleation of 3D islands. By interpolating high-resolution scanning tunneling microscopy measurements with continuum elasticity modeling, we assess the dependence of island's shape and elastic interaction on the substrate misorientation. Our results confirm that vicinal surfaces offer an additional degree of control over the shape and symmetry of self-assembled nanostructures.

Real-time spectro-ellipsometric approach to distinguish between two-dimensional Ge layer growth and Ge dot formation on SiO2 substrates

NASA Astrophysics Data System (ADS)

Akazawa, Housei

2018-04-01

Morphological evolution of Ge layers on SiO2 substrates grown by photo-excited chemical vapor deposition from GeH4 was monitored in real time by recording (Ψ, Δ) angles of spectroscopic ellipsometry and ex-situ analyzed by atomic force microscopy (AFM). Distinct Ψ-Δ trajectory shapes were demonstrated to discriminate the two-dimensional (2D) and three-dimensional (3D) growth modes. While the trajectory of 2D growth is characterized by a one-turn spiral, that of 3D growth consisted of three sections corresponding to initial wetting of the SiO2 surface, creation of nucleation centers, and dot growth. The critical point where the system turns into 2D or 3D growth can be in situ identified in terms of the directions of the Ψ-Δ trajectories. AFM images revealed characteristic changes in the microstructure, including self-assembling dots and dots merging with one another. While the root-mean-square surface roughness increased linearly against film thickness, the maximum peak-to-valley height deviated once from linear dependence and later returned back to it, which reflected coarsening of dots and embedding of valleys between dots.

Biaxially oriented CdTe films on glass substrate through nanostructured Ge/CaF2 buffer layers

NASA Astrophysics Data System (ADS)

Lord, R. J.; Su, P.-Y.; Bhat, I.; Zhang, S. B.; Lu, T.-M.; Wang, G.-C.

2015-09-01

Heteroepitaxial CdTe films were grown by metal organic chemical vapor deposition on glass substrates through nanostructured Ge/CaF2 buffer layers which were biaxially oriented. It allows us to explore the structural properties of multilayer biaxial semiconductor films which possess small angle grain boundaries and to test the principle of a solar cell made of such low-cost, low-growth-temperature semiconductor films. Through the x-ray diffraction and x-ray pole figure analysis, the heteroepitaxial relationships of the mutilayered films are determined as [111] in the out-of-plane direction and <1\\bar{1}0>CdTe//<1\\bar{1}0>Ge//{< \\bar{1}10> }{{{CaF}}2} in the in-plane direction. The I-V curves measured from an ITO/CdS/CdTe/Ge/CaF2/glass solar cell test structure shows a power conversion efficiency of ˜η = 1.26%, illustrating the initial success of such an approach. The observed non-ideal efficiency is believed to be due to a low shunt resistance and high series resistance as well as some residual large-angle grain boundary effects, leaving room for significant further improvement.

The role of surface passivation in controlling Ge nanowire faceting

DOE PAGES

Gamalski, A. D.; Tersoff, J.; Kodambaka, S.; ...

2015-11-05

In situ transmission electron microscopy observations of nanowire morphologies indicate that during Au-catalyzed Ge nanowire growth, Ge facets can rapidly form along the nanowire sidewalls when the source gas (here, digermane) flux is decreased or the temperature is increased. This sidewall faceting is accompanied by continuous catalyst loss as Au diffuses from the droplet to the wire surface. We suggest that high digermane flux and low temperatures promote effective surface passivation of Ge nanowires with H or other digermane fragments inhibiting diffusion and attachment of Au and Ge on the sidewalls. Furthermore, these results illustrate the essential roles of themore » precursor gas and substrate temperature in maintaining nanowire sidewall passivation, necessary to ensure the growth of straight, untapered, <111>-oriented nanowires.« less

Growth strategies to control tapering in Ge nanowires

NASA Astrophysics Data System (ADS)

Periwal, P.; Baron, T.; Gentile, P.; Salem, B.; Bassani, F.

2014-04-01

We report the effect of PH3 on the morphology of Au catalyzed Ge nanowires (NWs). Ge NWs were grown on Si (111) substrate at 400 °C in the presence of PH3, using vapor-liquid-solid method by chemical vapor deposition. We show that high PH3/GeH4 ratio causes passivation at NW surface. At high PH3 concentration phosphorous atoms attach itself on NW surface and form a self-protection coating that prevents conformal growth and leads to taper free nanostructures. However, in case of low PH3 flux the combination of axial and radial growth mechanism occurs resulting in conical structure. We have also investigated axial PH3-intrinsic junctions in Ge NWs. The unusual NW shape is attributed to a combination of catalyzed, uncatalyzed and diffusion induced growth.

Elemental boron-doped p(+)-SiGe layers grown by molecular beam epitaxy for infrared detector applications

NASA Technical Reports Server (NTRS)

Lin, T. L.; George, T.; Jones, E. W.; Ksendzov, A.; Huberman, M. L.

1992-01-01

SiGe/Si heterojunction internal photoemission (HIP) detectors have been fabricated utilizing molecular beam epitaxy of p(+)-SiGe layers on p(-)-Si substrates. Elemental boron from a high-temperature effusion cell was used as the dopant source during MBE growth, and high doping concentrations have been achieved. Strong infrared absorption, mainly by free-carrier absorption, was observed for the degenerately doped SiGe layers. The use of elemental boron as the dopant source allows a low MBE growth temperature, resulting in improved crystalline quality and smooth surface morphology of the Si(0.7)Ge(0.3) layers. Nearly ideal thermionic emission dark current characteristics have been obtained. Photoresponse of the HIP detectors in the long-wavelength infrared regime has been demonstrated.

Beneficial defects: exploiting the intrinsic polishing-induced wafer roughness for the catalyst-free growth of Ge in-plane nanowires

PubMed Central

2014-01-01

We outline a metal-free fabrication route of in-plane Ge nanowires on Ge(001) substrates. By positively exploiting the polishing-induced defects of standard-quality commercial Ge(001) wafers, micrometer-length wires are grown by physical vapor deposition in ultra-high-vacuum environment. The shape of the wires can be tailored by the epitaxial strain induced by subsequent Si deposition, determining a progressive transformation of the wires in SiGe faceted quantum dots. This shape transition is described by finite element simulations of continuous elasticity and gives hints on the equilibrium shape of nanocrystals in the presence of tensile epitaxial strain. PACS 81.07.Gf; 68.35.bg; 68.35.bj; 62.23.Eg PMID:25114649

High carrier mobility of Sn-doped polycrystalline-Ge films on insulators by thickness-dependent low-temperature solid-phase crystallization

NASA Astrophysics Data System (ADS)

Sadoh, Taizoh; Kai, Yuki; Matsumura, Ryo; Moto, Kenta; Miyao, Masanobu

2016-12-01

To realize the advanced thin-film transistors (TFTs), high-carrier-mobility semiconductor films on insulator structures should be fabricated with low-temperature processing conditions (≤500 °C). To achieve this, we investigated the solid-phase crystallization of amorphous-GeSn films on insulating substrates under a wide range of Sn concentrations (0%-20%), film thicknesses (30-500 nm), and annealing temperatures (380-500 °C). Our results reveal that a Sn concentration close to the solid solubility of Sn in Ge (˜2%) is effective in increasing the grain-size of poly-GeSn. In addition, we discovered that the carrier mobility depends on the film thickness, where the mobilities are determined by the counterbalance between two different carrier scattering mechanisms. Here, vacancy-related defects dominate the carrier scattering near the insulating substrates (≤˜120 nm), and grain-size determined by bulk nucleation dominates the grain-boundary scattering of thick films (≥˜200 nm). Consequently, we obtained the maximum mobilities in samples with a Sn concentration of 2% and a film thickness of 200 nm. The effect of increasing the grain-size of poly-GeSn by lowering the annealing temperature was also clarified. By combining these results, a very high carrier mobility of 320 cm2/Vs was obtained at a low temperature of 380 °C. This mobility is about 2.5 times as high as previously reported data for Ge and GeSn films grown at low temperatures (≤500 °C). Our technique therefore opens up the possibility of high-speed TFTs for use in the next generation of electronics.

Modulation of Cytochrome P450 Metabolism and Transport across Intestinal Epithelial Barrier by Ginger Biophenolics

PubMed Central

Yang, Chunhua; Donthamsetty, Shashikiran; Cantuaria, Guilherme; Jadhav, Gajanan R.; Vangala, Subrahmanyam; Reid, Michelle D.; Aneja, Ritu

2014-01-01

Natural and complementary therapies in conjunction with mainstream cancer care are steadily gaining popularity. Ginger extract (GE) confers significant health-promoting benefits owing to complex additive and/or synergistic interactions between its bioactive constituents. Recently, we showed that preservation of natural “milieu” confers superior anticancer activity on GE over its constituent phytochemicals, 6-gingerol (6G), 8-gingerol (8G), 10-gingerol (10G) and 6-shogaol (6S), through enterohepatic recirculation. Here we further evaluate and compare the effects of GE and its major bioactive constituents on cytochrome P450 (CYP) enzyme activity in human liver microsomes by monitoring metabolites of CYP-specific substrates using LC/MS/MS detection methods. Our data demonstrate that individual gingerols are potent inhibitors of CYP isozymes, whereas GE exhibits a much higher half-maximal inhibition value, indicating no possible herb-drug interactions. However, GE's inhibition of CYP1A2 and CYP2C8 reflects additive interactions among the constituents. In addition, studies performed to evaluate transporter-mediated intestinal efflux using Caco-2 cells revealed that GE and its phenolics are not substrates of P-glycoprotein (Pgp). Intriguingly, however, 10G and 6S were not detected in the receiver compartment, indicating possible biotransformation across the Caco-2 monolayer. These data strengthen the notion that an interplay of complex interactions among ginger phytochemicals when fed as whole extract dictates its bioactivity highlighting the importance of consuming whole foods over single agents. Our study substantiates the need for an in-depth analysis of hepatic biotransformation events and distribution profiles of GE and its active phenolics for the design of safe regimens. PMID:25251219

Room temperature direct band gap emission characteristics of surfactant mediated grown compressively strained Ge films

NASA Astrophysics Data System (ADS)

Katiyar, Ajit K.; Grimm, Andreas; Bar, R.; Schmidt, Jan; Wietler, Tobias; Joerg Osten, H.; Ray, Samit K.

2016-10-01

Compressively strained Ge films have been grown on relaxed Si0.45Ge0.55 virtual substrates using molecular beam epitaxy in the presence of Sb as a surfactant. Structural characterization has shown that films grown in the presence of surfactant exhibit very smooth surfaces with a relatively higher strain value in comparison to those grown without any surfactant. The variation of strain with increasing Ge layer thickness was analyzed using Raman spectroscopy. The strain is found to be reduced with increasing film thickness due to the onset of island nucleation following Stranski-Krastanov growth mechanism. No phonon assisted direct band gap photoluminescence from compressively strained Ge films grown on relaxed Si0.45Ge0.55 has been achieved up to room temperature. Excitation power and temperature dependent photoluminescence have been studied in details to investigate the origin of different emission sub-bands.

Conduction band offset at GeO{sub 2}/Ge interface determined by internal photoemission and charge-corrected x-ray photoelectron spectroscopies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, W. F.; Nishimula, T.; Nagashio, K.

2013-03-11

We report a consistent conduction band offset (CBO) at a GeO{sub 2}/Ge interface determined by internal photoemission spectroscopy (IPE) and charge-corrected X-ray photoelectron spectroscopy (XPS). IPE results showed that the CBO value was larger than 1.5 eV irrespective of metal electrode and substrate type variance, while an accurate determination of valence band offset (VBO) by XPS requires a careful correction of differential charging phenomena. The VBO value was determined to be 3.60 {+-} 0.2 eV by XPS after charge correction, thus yielding a CBO (1.60 {+-} 0.2 eV) in excellent agreement with the IPE results. Such a large CBO (>1.5more » eV) confirmed here is promising in terms of using GeO{sub 2} as a potential passivation layer for future Ge-based scaled CMOS devices.« less

Ge nanopillar solar cells epitaxially grown by metalorganic chemical vapor deposition

PubMed Central

Kim, Youngjo; Lam, Nguyen Dinh; Kim, Kangho; Park, Won-Kyu; Lee, Jaejin

2017-01-01

Radial junction solar cells with vertically aligned wire arrays have been widely studied to improve the power conversion efficiency. In this work, we report the first Ge nanopillar solar cell. Nanopillar arrays are selectively patterned on p-type Ge (100) substrates using nanosphere lithography and deep reactive ion etching processes. Nanoscale radial and planar junctions are realized by an n-type Ge emitter layer which is epitaxially grown by MOCVD using isobutylgermane. In situ epitaxial surface passivation is employed using an InGaP layer to avoid high surface recombination rates and Fermi level pinning. High quality n-ohmic contact is realized by protecting the top contact area during the nanopillar patterning. The short circuit current density and the power conversion efficiency of the Ge nanopillar solar cell are demonstrated to be improved up to 18 and 30%, respectively, compared to those of the Ge solar cell with a planar surface. PMID:28209964

Interfacial processes in the Pd/a-Ge:H system

NASA Astrophysics Data System (ADS)

Edelman, F.; Cytermann, C.; Brener, R.; Eizenberg, M.; Weil, R.; Beyer, W.

1993-06-01

The kinetics of phase transformation has been studied in a two-layer structure of Pd/a-Ge:H after vacuum annealing at temperatures from 180 to 500°C. The a-Ge:H was deposited at 250°C on both c-Si and cleaved NaCl substrates in an RF glow discharge from a GeH 4/H 2 mixture. It was found that, similarly to the Pd/c-Ge and the Pd/a-Ge (e-gun deposited) systems, in the case of 0.15-0.2 μm Pd/0.6-1.0 μm a-Ge:H interfacial germanides formed first through the production of Pd 2Ge (plus a small amount of PdGe), and then PdGe was produced. The growth of both compounds was found to be diffusion-controlled. The nonreacted a-Ge:H layer beneath the germanide overlayer crystallized at 400-500°C. A reverse sequence of germanides formation was revealed in the case of 50 nm Pd/30 nm a-Ge:H, studied by in situ heat treatment in the TEM utilizing non-supported samples. The first germanide detected was PdGe and then, as a result of PdGe and Ge reaction or the PdGe decomposition, Pd 2Ge formed. The temperature dependence of the incubation time before the first ˜ 10 nm PdGe grains formed, followed an Arrhenius curve with an activation energy of 1.45 eV.

Electron Transport Properties of Ge nanowires

NASA Astrophysics Data System (ADS)

Hanrath, Tobias; Khondaker, Saiful I.; Yao, Zhen; Korgel, Brian A.

2003-03-01

Electron Transport Properties of Ge nanowires Tobias Hanrath*, Saiful I. Khondaker, Zhen Yao, Brian A. Korgel* *Dept. of Chemical Engineering, Dept. of Physics, Texas Materials Institute, and Center for Nano- and Molecular Science and Technology University of Texas at Austin, Austin, Texas 78712-1062 e-mail: korgel@mail.che.utexas.edu Germanium (Ge) nanowires with diameters ranging from 6 to 50 nm and several micrometer in length were grown via a supercritical fluid-liquid-solid synthesis. Parallel electron energy loss spectroscopy (PEELS) was employed to study the band structure and electron density in the Ge nanowires. The observed increase in plasmon peak energy and peak width with decreasing nanowire diameter is attributed to quantum confinement effects. For electrical characterization, Ge nanowires were deposited onto a patterned Si/SiO2 substrate. E-beam lithography was then used to form electrode contacts to individual nanowires. The influence of nanowire diameter, surface chemistry and crystallographic defects on electron transport properties were investigated and the comparison of Ge nanowire conductivity with respect to bulk, intrinsic Ge will be presented.

Impacts of excimer laser annealing on Ge epilayer on Si

NASA Astrophysics Data System (ADS)

Huang, Zhiwei; Mao, Yichen; Yi, Xiaohui; Lin, Guangyang; Li, Cheng; Chen, Songyan; Huang, Wei; Wang, Jianyuan

2017-02-01

The impacts of excimer laser annealing on the crystallinity of Ge epilayers on Si substrate grown by low- and high-temperature two-step approach in an ultra-high vacuum chemical vapor deposition system were investigated. The samples were treated by excimer laser annealing (ELA) at various laser power densities with the temperature above the melting point of Ge, while below that of Si, resulting in effective reduction of point defects and dislocations in the Ge layer with smooth surface. The full-width at half-maximum (FWHM) of X-ray diffraction patterns of the low-temperature Ge epilayer decreases with the increase in laser power density, indicating the crystalline improvement and negligible effect of Ge-Si intermixing during ELA processes. The short laser pulse time and large cooling rate cause quick melting and recrystallization of Ge epilayer on Si in the non-thermal equilibrium process, rendering tensile strain in Ge epilayer as calculated quantitatively with thermal mismatch between Si and Ge. The FWHM of X-ray diffraction patterns is significantly reduced for the two-step grown samples after treated by a combination of ELA and conventional furnace thermal annealing, indicating that the crystalline of Ge epilayer is improved more effectively with pre- annealing by excimer laser.

Self-assembled antireflection coatings for light trapping based on SiGe random metasurfaces

NASA Astrophysics Data System (ADS)

Bouabdellaoui, Mohammed; Checcucci, Simona; Wood, Thomas; Naffouti, Meher; Sena, Robert Paria; Liu, Kailang; Ruiz, Carmen M.; Duche, David; le Rouzo, Judikael; Escoubas, Ludovic; Berginc, Gerard; Bonod, Nicolas; Zazoui, Mimoun; Favre, Luc; Metayer, Leo; Ronda, Antoine; Berbezier, Isabelle; Grosso, David; Gurioli, Massimo; Abbarchi, Marco

2018-03-01

We demonstrate a simple self-assembly method based on solid state dewetting of ultrathin silicon films and germanium deposition for the fabrication of efficient antireflection coatings on silicon for light trapping. We fabricate SiGe islands with a high surface density, randomly positioned and broadly varied in size. This allows one to reduce the reflectance to low values in a broad spectral range (from 500 nm to 2500 nm) and a broad angle (up to 55°) and to trap within the wafer a large portion of the impinging light (˜40 % ) also below the band gap, where the Si substrate is nonabsorbing. Theoretical simulations agree with the experimental results, showing that the efficient light coupling into the substrate is mediated by Mie resonances formed within the SiGe islands. This lithography-free method can be implemented on arbitrarily thick or thin SiO2 layers and its duration only depends on the sample thickness and on the annealing temperature.

Direct Growth of Graphene Film on Germanium Substrate

PubMed Central

Wang, Gang; Zhang, Miao; Zhu, Yun; Ding, Guqiao; Jiang, Da; Guo, Qinglei; Liu, Su; Xie, Xiaoming; Chu, Paul K.; Di, Zengfeng; Wang, Xi

2013-01-01

Graphene has been predicted to play a role in post-silicon electronics due to the extraordinary carrier mobility. Chemical vapor deposition of graphene on transition metals has been considered as a major step towards commercial realization of graphene. However, fabrication based on transition metals involves an inevitable transfer step which can be as complicated as the deposition of graphene itself. By ambient-pressure chemical vapor deposition, we demonstrate large-scale and uniform depositon of high-quality graphene directly on a Ge substrate which is wafer scale and has been considered to replace conventional Si for the next generation of high-performance metal-oxide-semiconductor field-effect transistors (MOSFETs). The immiscible Ge-C system under equilibrium conditions dictates graphene depositon on Ge via a self-limiting and surface-mediated process rather than a precipitation process as observed from other metals with high carbon solubility. Our technique is compatible with modern microelectronics technology thus allowing integration with high-volume production of complementary metal-oxide-semiconductors (CMOS). PMID:23955352

Formation of nickel germanides from Ni layers with thickness below 10 nm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jablonka, Lukas; Kubart, Tomas; Primetzhofer, Daniel

2017-03-01

The authors have studied the reaction between a Ge (100) substrate and thin layers of Ni ranging from 2 to 10 nm in thickness. The formation of metal-rich Ni5Ge3Ni5Ge3 was found to precede that of the monogermanide NiGe by means of real-time in situ x-ray diffraction during ramp-annealing and ex situ x-ray pole figure analyses for phase identification. The observed sequential growth of Ni5Ge3Ni5Ge3 and NiGe with such thin Ni layers is different from the previously reported simultaneous growth with thicker Ni layers. The phase transformation from Ni5Ge3Ni5Ge3 to NiGe was found to be nucleation-controlled for Ni thicknesses <5 nm<5more » nm, which is well supported by thermodynamic considerations. Specifically, the temperature for the NiGe formation increased with decreasing Ni (rather Ni5Ge3Ni5Ge3) thickness below 5 nm. In combination with sheet resistance measurement and microscopic surface inspection of samples annealed with a standard rapid thermal processing, the temperature range for achieving morphologically stable NiGe layers was identified for this standard annealing process. As expected, it was found to be strongly dependent on the initial Ni thickness« less

Crystallization of Electrodeposited Germanium Thin Film on Silicon (100).

PubMed

Abidin, Mastura Shafinaz Zainal; Matsumura, Ryo; Anisuzzaman, Mohammad; Park, Jong-Hyeok; Muta, Shunpei; Mahmood, Mohamad Rusop; Sadoh, Taizoh; Hashim, Abdul Manaf

2013-11-06

We report the crystallization of electrodeposited germanium (Ge) thin films on n-silicon (Si) (100) by rapid melting process. The electrodeposition was carried out in germanium (IV) chloride: propylene glycol (GeCl₄:C₃H₈O₂) electrolyte with constant current of 50 mA for 30 min. The measured Raman spectra and electron backscattering diffraction (EBSD) images show that the as-deposited Ge thin film was amorphous. The crystallization of deposited Ge was achieved by rapid thermal annealing (RTA) at 980 °C for 1 s. The EBSD images confirm that the orientations of the annealed Ge are similar to that of the Si substrate. The highly intense peak of Raman spectra at 300 cm -1 corresponding to Ge-Ge vibration mode was observed, indicating good crystal quality of Ge. An additional sub peak near to 390 cm -1 corresponding to the Si-Ge vibration mode was also observed, indicating the Ge-Si mixing at Ge/Si interface. Auger electron spectroscopy (AES) reveals that the intermixing depth was around 60 nm. The calculated Si fraction from Raman spectra was found to be in good agreement with the value estimated from Ge-Si equilibrium phase diagram. The proposed technique is expected to be an effective way to crystallize Ge films for various device applications as well as to create strain at the Ge-Si interface for enhancement of mobility.

Organometallic chemical vapor deposition and characterization of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates

NASA Technical Reports Server (NTRS)

Xing, G. C.; Bachmann, Klaus J.; Posthill, J. B.; Timmons, M. L.

1993-01-01

The epitaxial growth of ZnGe(1-x)Si(x)P2-Ge alloys on GaP substrates by open tube organometallic chemical vapor deposition (OMCVD) is reported. The chemical composition of the alloys characterized by energy dispersive X-ray spectroscopy shows that alloys with x up to 0.13 can be deposited on (001) GaP. Epitaxial growth with mirror smooth surface morphology was achieved for x less than or equal to 0.05. Transmission electron microscopy (TEM) micrographs of these alloys show specular epitaxy and the absence of microstructural defects indicating a defect density of less than 10(exp 7) cm(sup -2). Selected area electron diffraction pattern of the alloy shows that the epitaxial layer crystallizes in the chalcopyrite structure with relatively weak superlattice reflections indicating certain degree of randomness in the cation sublattice. Hall measurements show that the alloys are p-type, like the unalloyed films; the carrier concentration, however, dropped about 10 times from 2 x 10(exp 18) to 2 x 10(exp 17) cm(sup -3). Absorption measurements indicate that the band tailing in the absorption spectra of the alloy was shifted about 0.04 eV towards shorter wavelength as compared to the unalloyed material. Diodes fabricated from the n(+)-GaP/p-ZnSiP2-ZnGeP2-Ge heterostructure at x = 0.05 have a reverse break-down voltage of -10.8 V and a reverse saturation current density of approximately 6 x 10(exp -8) A/sq cm.

K-Band Si/SiGe HBT MMIC Amplifiers Using Lumped Passive Components with a Micromachined Structure

NASA Technical Reports Server (NTRS)

Lu, Liang-Hung; Rieh, Jae-Sung; Bhattacharya, Pallab; Katechi, Linda P. B.; Croke, E. T.; Ponchak, George E.; Alterovitz, Samuel A.

2000-01-01

Using Si/SiGe heterojunction bipolar transistors with a maximum oscillation frequency of 52 GHz and a novel structure for passive components, a two-stage K-band lumped-element amplifier has been designed and fabricated on high-resistivity Si substrates. The chip size including biasing and RF chokes is 0.92 x 0.67 sq mm.

GeSn/Si Avalanche Photodetectors on Si substrates

DTIC Science & Technology

2016-09-16

of processes for different photo detectors. In-depth of study has been conducted for GeSn photo conductors and photodiodes. A summary of the...The material growth mechanism was in-depth studied; secondly, the material and optical characterizations have been conducted , including SEM, TEM, XRD...investigated. The material growth mechanism was in-depth studied; secondly, the material and optical characterizations have been conducted , including

High-aspect-ratio and high-flatness Cu3(SiGe) nanoplatelets prepared by chemical vapor deposition.

PubMed

Klementová, Mariana; Palatinus, Lukás; Novotný, Filip; Fajgar, Radek; Subrt, Jan; Drínek, Vladislav

2013-06-01

Cu3(SiGe) nanoplatelets were synthesized by low-pressure chemical vapor deposition of a SiH3C2H5/Ge2(CH3)6 mixture on a Cu-substrate at 500 degrees C, total pressure of 110-115 Pa, and Ge/Si molar ratio of 22. The nanoplatelets with composition Cu76Si15Ge12 are formed by the 4'-phase, and they are flattened perpendicular to the [001] direction. Their lateral dimensions reach several tens of micrometers in size, but they are only about 50 nm thick. Their surface is extremely flat, with measured root mean square roughness R(q) below 0.2 nm. The nanoplatelets grow via the non-catalytic vapor-solid mechanism and surface growth. In addition, nanowires and nanorods of various Cu-Si-Ge alloys were also obtained depending on the experimental conditions. Morphology of the resulting Cu-Si-Ge nanoobjects is very sensitive to the experimental parameters. The formation of nanoplatelets is associated with increased amount of Ge in the alloy.

Fabrication and ferromagnetism of Si-SiGe/MnGe core-shell nanopillars.

PubMed

Wang, Liming; Liu, Tao; Wang, Shuguang; Zhong, Zhenyang; Jia, Quanjie; Jiang, Zuimin

2016-10-07

Si-Si0.5Ge0.5/Mn0.08Ge0.92 core-shell nanopillar samples were fabricated on ordered Si nanopillar patterned substrates by molecular beam epitaxy at low temperatures. The magnetic properties of the samples are found to depend heavily on the growth temperature of the MnGe layer. The sample grown at a moderate temperature of 300 °C has the highest Curie temperature of 240 K as well as the strongest ferromagnetic signals. On the basis of the microstructural results, the ferromagnetic properties of the samples are believed to come from the intrinsic Mn-doped amorphous or crystalline Ge ferromagnetic phase rather than any intermetallic ferromagnetic compounds of Mn and Ge. After being annealed at a temperature of 500 °C, all the samples exhibit the same Curie temperature of 220 K, which is in sharp contrast to the different Curie temperature for the as-grown samples, and the ferromagnetism for the annealed samples comes from Mn5GeSi2 compounds which are formed during the annealing.

Effect of Boron Doping on High-Resolution X-Ray Diffraction Metrology

NASA Astrophysics Data System (ADS)

Faheem, M.; Zhang, Y.; Dai, X.

2018-03-01

The effect of boron (B) doping on high-resolution X-ray diffraction (HXRD) metrology has been investigated. Twelve samples of Si1-xGex films were epitaxially grown on Si (100) substrates with different thicknesses, germanium (Ge) concentrations and with/without B dopants. Secondary ion mass spectroscopy (SIMS) and HXRD were employed for measurements of B doping, Ge concentration, strain, and thickness of the layers. The SIMS results show the absence of B in two samples while the rest of the samples have B doping in the range of 8.40 × 1018-8.7 × 1020 atoms/cm3 with Ge concentration of 13.3-55.2 at.%. The HXRD measurements indicate the layers thickness of 7.07-108.13 nm along with Ge concentration of 12.82-49.09 at.%. The difference in the Ge concentration measured by SIMS and HXRD was found to deend on B doping. For the undoped samples, the difference is 0.5 at.% and increases with B doping but with no linear proportionality. The difference in the Ge concentration was 7.11 at.% for the highly B-doped (8.7 × 1020 atoms/cm3) sample. The B doping influences the Si1-xGex structure, causing a change in the lattice parameter and producing tensile strains shifting Si1-xGex peaks towards Si (100) substrate peaks in the HXRD diffraction patterns. As a result, Vegard's law is no longer effective and makes a high impact on the HXRD measurement. The comparison between symmetric (004) and asymmetric (+113, +224) reciprocal space mappings (RSM) showed a slight difference in Ge concentration between the undoped and lower B-doped samples. However, there is a change of 0.21 at.% observed for the highly doped Si1-xGex samples. RSM's (+113) demonstrate the small SiGe peak broadening as B doping increases, which indicates a minor crystal distortion.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidtbauer, Jan; Bansen, Roman; Heimburger, Robert

Germanium nanowires (NWs) were grown onto Ge(111) substrates by the vapor-liquid-solid process using gold droplets. The growth was carried out in a molecular beam epitaxy chamber at substrate temperatures between 370 Degree-Sign C and 510 Degree-Sign C. The resulting nanowire growth rate turns out to be highly dependent on the substrate temperature exhibiting the maximum at T = 430 Degree-Sign C. The temperature dependence of growth rate can be attributed to surface diffusion both along the substrate and nanowire sidewalls. Analyzing the diffusive material transport yields a diffusion length of 126 nm at a substrate temperature of 430 Degree-Sign C.

Superthin Solar Cells Based on AIIIBV/Ge Heterostructures

NASA Astrophysics Data System (ADS)

Pakhanov, N. A.; Pchelyakov, O. P.; Vladimirov, V. M.

2017-11-01

A comparative analysis of the prospects of creating superthin, light-weight, and highly efficient solar cells based on AIIIBV/InGaAs and AIIIBV/Ge heterostructures is performed. Technological problems and prospects of each variant are discussed. A method of thinning of AIIIBV/Ge heterostructures with the use of an effective temporary carrier is proposed. The method allows the process to be performed almost with no risk of heterostructure fracture, thinning of the Ge junction down to several tens of micrometers (or even several micrometers), significant enhancement of the yield of good structures, and also convenient and reliable transfer of thinned solar cells to an arbitrary light and flexible substrate. Such a technology offers a possibility of creating high-efficiency thin and light solar cells for space vehicles on the basis of mass-produced AIIIBV/Ge heterostructures.

High-performance flexible resistive memory devices based on Al2O3:GeOx composite

NASA Astrophysics Data System (ADS)

Behera, Bhagaban; Maity, Sarmistha; Katiyar, Ajit K.; Das, Samaresh

2018-05-01

In this study a resistive switching random access memory device using Al2O3:GeOx composite thin films on flexible substrate is presented. A bipolar switching characteristic was observed for the co-sputter deposited Al2O3:GeOx composite thin films. Al/Al2O3:GeOx/ITO/PET memory device shows excellent ON/OFF ratio (∼104) and endurance (>500 cycles). GeOx nanocrystals embedded in the Al2O3 matrix have been found to play a significant role in enhancing the switching characteristics by facilitating oxygen vacancy formation. Mechanical endurance was retained even after several bending. The conduction mechanism of the device was qualitatively discussed by considering Ohmic and SCLC conduction. This flexible device is a potential candidate for next-generation electronics device.

Ge nanocrystals formed by furnace annealing of Ge(x)[SiO2](1-x) films: structure and optical properties

NASA Astrophysics Data System (ADS)

Volodin, V. A.; Cherkov, A. G.; Antonenko, A. Kh; Stoffel, M.; Rinnert, H.; Vergnat, M.

2017-07-01

Ge(x)[SiO2](1-x) (0.1  ⩽  x  ⩽  0.4) films were deposited onto Si(0 0 1) or fused quartz substrates using co-evaporation of both Ge and SiO2 in high vacuum. Germanium nanocrystals were synthesized in the SiO2 matrix by furnace annealing of Ge x [SiO2](1-x) films with x  ⩾  0.2. According to electron microscopy and Raman spectroscopy data, the average size of the nanocrystals depends weakly on the annealing temperature (700, 800, or 900 °C) and on the Ge concentration in the films. Neither amorphous Ge clusters nor Ge nanocrystals were observed in as-deposited and annealed Ge0.1[SiO2]0.9 films. Infrared absorption spectroscopy measurements show that the studied films do not contain a noticeable amount of GeO x clusters. After annealing at 900 °C intermixing of germanium and silicon atoms was still negligible thus preventing the formation of GeSi nanocrystals. For annealed samples, we report the observation of infrared photoluminescence at low temperatures, which can be explained by exciton recombination in Ge nanocrystals. Moreover, we report strong photoluminescence in the visible range at room temperature, which is certainly due to Ge-related defect-induced radiative transitions.

Impact of dislocation densities on n+/p and p+/n junction GaAs diodes and solar cells on SiGe virtual substrates

NASA Astrophysics Data System (ADS)

Andre, C. L.; Wilt, D. M.; Pitera, A. J.; Lee, M. L.; Fitzgerald, E. A.; Ringel, S. A.

2005-07-01

Recent experimental measurements have shown that in GaAs with elevated threading dislocation densities (TDDs) the electron lifetime is much lower than the hole lifetime [C. L. Andre, J. J. Boeckl, D. M. Wilt, A. J. Pitera, M. L. Lee, E. A. Fitzgerald, B. M. Keyes, and S. A. Ringel, Appl. Phys. Lett. 84, 3884 (2004)]. This lower electron lifetime suggests an increase in depletion region recombination and thus in the reverse saturation current (J0 for an n+/p diode compared with a p+/n diode at a given TDD. To confirm this, GaAs diodes of both polarities were grown on compositionally graded Ge /Si1-xGex/Si (SiGe) substrates with a TDD of 1×106cm-2. It is shown that the ratio of measured J0 values is consistent with the inverse ratio of the expected lifetimes. Using a TDD-dependent lifetime in solar cell current-voltage models we found that the Voc, for a given short-circuit current, also exhibits a poorer TDD tolerance for GaAs n+/p solar cells compared with GaAs p+/n solar cells. Experimentally, the open-circuit voltage (Voc) for the n+/p GaAs solar cell grown on a SiGe substrate with a TDD of ˜1×106cm-2 was ˜880mV which was significantly lower than the ˜980mV measured for a p+/n GaAs solar cell grown on SiGe at the same TDD and was consistent with the solar cell modeling results reported in this paper. We conclude that p+/n polarity GaAs junctions demonstrate superior dislocation tolerance than n+/p configured GaAs junctions, which is important for optimization of lattice-mismatched III-V devices.

Quantum dot formation by molecular beam epitaxy of Ge on Si(100)

NASA Astrophysics Data System (ADS)

Chaparro, Sergio Arturo

1999-11-01

A new technique for producing electron systems with quantum confinement in three dimensions, quantum dots, has been studied. These quantum dots are coherent islands spontaneously formed at the early stages of Ge/Si(100) epitaxy due to the misfit of the system. Our goal is to gain understanding and control of the growth process so uniform quantum dot ensembles can be created for possible use in optoelectronic devices. A UHV Molecular Beam Epitaxy (MBE) growth system was built and calibrated to grow our samples. The samples were prepared by depositing Ge onto a Si(100) surface cleaned by flash desorption of the native oxides. Varying the growth rates from 0.6 ML/min to 4.0 ML/min, the substrate temperature from 450°C to 600°C, and the coverage from 3.5 ML to 14 ML produces different sample morphologies. After growth, the samples were analyzed both in situ and ex situ. The in situ analysis consisted of Auger electron spectroscopy for elemental analysis and reflection high energy electron diffraction, for surface structure analysis. The ex situ analysis included atomic force microscopy (AFM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM). Many digital images were obtained from the microscope analysis. A novel, computer based, analysis was developed to extract the islands parameters from the microscope images. This data, which includes island area and average height for each island on every image, was used for a statistical analysis. Also from the data, island size distributions (histograms of island size) were generated. These measurements confirm that islands form after growth of a 3 ML wetting layer and that islands evolve as they grow. As more Ge is deposited these islands grow and as they grow they evolve from huts, square based pyramids, to domes, truncated pyramids, to dislocated domes. Our results show that the substrate temperature, deposition rate, and amount of deposited material are factors that affect the growth evolution. Higher growth temperature affects the size at which islands evolve from one type of island to another, also introduces new strain release mechanisms such as alloying and trench formation that compete with dislocation formation. Finally a detailed morphological characterization of the observed islands was done.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akatsu, T.; Bourdelle, K.K.; Richtarch, C.

Extended defects formed after hydrogen implantation into Si and Ge (100) substrates and subsequent thermal anneals were investigated by transmission electron microscopy. The majority of the extended defects formed in both materials were platelet-like structures lying on {l_brace}100{r_brace} and {l_brace}111{r_brace} planes. We found {l_brace}100{r_brace} platelets not only parallel but also perpendicular to the surface. In Ge wafers, high density of {l_brace}311{r_brace} defects and nanobubbles with the average size of 2 nm were observed. The difference between two materials can be attributed to the weaker strength of Ge-H bond.

Structural and electrical investigations of MBE-grown SiGe nanoislands

NASA Astrophysics Data System (ADS)

Şeker, İsa; Karatutlu, Ali; Gürbüz, Osman; Yanık, Serhat; Bakış, Yakup; Karakız, Mehmet

2018-01-01

SiGe nanoislands were grown by Molecular Beam Epitaxy (MBE) method on Si (100) substrates with comparative growth parameters such as annealing temperature, top Ge content and layer-by-layer annealing (LBLA). XRD and Raman data suggest that annealing temperature, top Ge content and layer-by-layer annealing (LBLA) can overall give a control not only over the amorphous content but also over yielding the strained Ge layer formation in addition to mostly Ge crystallites. Depending on the layer design and growth conditions, size of the crystallites was observed to be changed. Four Point Probe (FPP) Method via Semiconductor Analyzer shows that 100 °C rise in annealing temperature of the samples with Si0.25Ge0.75 top layers caused rougher islands with vacancies which further resulted in the formation of laterally higher resistive thin film sheets. However, vertically performed I-AFM analysis produced higher I-V values which suggest that the vertical and horizantal conductance mechanisms appear to be different. Ge top-layered samples gained greater crystalline structure and better surface conductivity where LBLA resulted in the formation of Ge nucleation and tight 2D stacking resulting in enhanced current values.

Influence of Ge addition on the optical properties of As40Se50Ge10 thin film probed by spectroscopy techniques

NASA Astrophysics Data System (ADS)

Naik, Ramakanta; Pradhan, Jagnaseni; Sripan, Chinnaiyah; Ganesan, R.

2018-05-01

The thin films of As40Se60 and As40Se50Ge10 were prepared on glass substrates by thermal evaporation method with thickness 1000 nm. The prepared films were amorphous in nature which was confirmed through X-ray diffraction. The chemical composition and the surface picture were obtained from energy dispersive X-ray analysis and Scanning Electron Microscopy analysis. The transmission data of the two films were collected in the wavelength range 400-1000 nm. The transmission percentage is found to be decreased whereas the absorption coefficient is increased with the Ge addition. The addition of Ge into As40Se60 is found to increase the refractive index and the extinction coefficient of As40Se50Ge10 thin film. The decrease in optical band gap is explained on the basis of increase in density of states and disorderness due to Ge addition. The optical absorption in the film is due to allowed indirect transition, and the homopolar bond density is increased with Ge addition. The Raman shift observed in the two films clearly supports the optical changes due to Ge addition.

High Mobility SiGe/Si n-Type Structures and Field Effect Transistors on Sapphire Substrates

NASA Technical Reports Server (NTRS)

Alterovitz, Samuel A.; Ponchak, George E.; Mueller, Carl H.; Croke, Edward T.

2004-01-01

SiGe/Si n-type modulation doped field effect transistors (MODFETs) fabricated on sapphire substrates have been characterized at microwave frequencies for the first time. The highest measured room temperature electron mobility is 1380 sq cm/V-sec at a carrier density of 1.8 x 10(exp 12)/sq cm for a MODFET structure, and 900 sq cm/V-sec at a carrier density of 1.3 x 10/sq cm for a phosphorus ion implanted sample. A two finger, 2 x 200 micron gate n-MODFET has a peak transconductance of 37 mS/mm at a drain to source voltage of 2.5 V and a transducer gain of 6.4 dB at 1 GHz.

Observation of hole accumulation in Ge/Si core/shell nanowires using off-axis electron holography.

PubMed

Li, Luying; Smith, David J; Dailey, Eric; Madras, Prashanth; Drucker, Jeff; McCartney, Martha R

2011-02-09

Hole accumulation in Ge/Si core/shell nanowires (NWs) has been observed and quantified using off-axis electron holography and other electron microscopy techniques. The epitaxial [110]-oriented Ge/Si core/shell NWs were grown on Si (111) substrates by chemical vapor deposition through the vapor-liquid-solid growth mechanism. High-angle annular-dark-field scanning transmission electron microscopy images and off-axis electron holograms were obtained from specific NWs. The excess phase shifts measured by electron holography across the NWs indicated the presence of holes inside the Ge cores. Calculations based on a simplified coaxial cylindrical model gave hole densities of (0.4 ± 0.2) /nm(3) in the core regions.

Interface doping of conjugated organic films by means of diffusion of atomic components from the surfaces of semiconductors and of metal oxides.

PubMed

Komolov, A S; Akhremtchik, S N; Lazneva, E F

2011-08-15

The paper reports the results on the interface formation of 5-10 nm thick conjugated layers of Cu-phthalocyanine (CuPc) with a number of solid surfaces: polycrystalline Au, (SiO(2))n-Si, ZnO(0 0 0 1), Si(1 0 0), Ge(1 1 1), CdS(0 0 0 1) and GaAs(1 0 0). The results were obtained using Auger electron spectroscopy (AES) and low-energy target current electron spectroscopy (TCS). The organic overlayers were thermally deposited in situ in UHV onto substrate surfaces. The island-like organic deposits were excluded from the analysis so that only uniform organic deposits were considered. In the cases of polycrystalline Au, Si(1 0 0) and Ge(1 1 1) substrates the AES peaks of the substrate material attenuated down to the zero noise level upon the increase of the CuPc film thickness of 8-10 nm. The peaks corresponding to oxygen atoms in the case of SiO(2) substrate, and to atoms from the ZnO, GaAs and CdS substrates were clearly registered in the AES spectra of the 8-10 nm thick CuPc deposits. The relative concentration of the substrate atomic components diffused into the film was different from their relative concentration at the pure substrate surface. The concentration of the substrate dopant atoms in the CuPc film was estimated as one atom per one CuPc molecule. Using the target current electron spectroscopy, it was shown that the substrate atoms admixed in the CuPc film account for the appearance of a new peak in the density of unoccupied electronic states. Formation of intermediate TCS spectra until the CuPc deposit reaches 2-3 nm was observed in the cases of GaAs(1 0 0), ZnO(0 0 0 1), Ge(1 1 1) surfaces. The intermediate spectra show a less pronounced peak structure different from the one typical for the CuPc films. It was suggested that the intermediate layer was formed by the CuPc molecules fully or partially decomposed due to the interaction with the relatively reactive semiconductor surfaces. Copyright © 2010 Elsevier B.V. All rights reserved.

Impurity measurements in semiconductor materials using trace element accelerator mass spectrometry

NASA Astrophysics Data System (ADS)

McDaniel, F. D.; Datar, S. A.; Nigam, M.; Ravi Prasad, G. V.

2002-05-01

Accelerator mass spectrometry (AMS) is commonly used to determine the abundance ratios of long-lived isotopes such as 10B, 14C, 36Cl, 129I, etc. to their stable counterparts at levels as low as 10 -16. Secondary ion mass spectrometry (SIMS) is routinely used to determine impurity levels in materials by depth profiling techniques. Trace-element accelerator mass spectrometry (TEAMS) is a combination of AMS and SIMS, presently being used at the University of North Texas, for high-sensitivity (ppb) impurity analyses of stable isotopes in semiconductor materials. The molecular break-up characteristics of AMS are used with TEAMS to remove the molecular interferences present in SIMS. Measurements made with different substrate/impurity combinations demonstrate that TEAMS has higher sensitivity for many elements than other techniques such as SIMS and can assist with materials characterization issues. For example, measurements of implanted As in the presence of Ge in Ge xSi 1- x/Si is difficult with SIMS because of molecular interferences from 74GeH, 29Si 30Si 16O, etc. With TEAMS, the molecular interferences are removed and higher sensitivities are obtained. Measured substrates include Si, SiGe, CoSi 2, GaAs and GaN. Measured impurities include B, N, F, Mg, P, Cl, Cr, Fe, Ni, Co, Cu, Zn, Ge, As, Se, Mo, Sn and Sb. A number of measurements will be presented to illustrate the range and power of TEAMS.

Understanding the growth mechanism of graphene on Ge/Si(001) surfaces

NASA Astrophysics Data System (ADS)

Dabrowski, J.; Lippert, G.; Avila, J.; Baringhaus, J.; Colambo, I.; Dedkov, Yu S.; Herziger, F.; Lupina, G.; Maultzsch, J.; Schaffus, T.; Schroeder, T.; Kot, M.; Tegenkamp, C.; Vignaud, D.; Asensio, M.-C.

2016-08-01

The practical difficulties to use graphene in microelectronics and optoelectronics is that the available methods to grow graphene are not easily integrated in the mainstream technologies. A growth method that could overcome at least some of these problems is chemical vapour deposition (CVD) of graphene directly on semiconducting (Si or Ge) substrates. Here we report on the comparison of the CVD and molecular beam epitaxy (MBE) growth of graphene on the technologically relevant Ge(001)/Si(001) substrate from ethene (C2H4) precursor and describe the physical properties of the films as well as we discuss the surface reaction and diffusion processes that may be responsible for the observed behavior. Using nano angle resolved photoemission (nanoARPES) complemented by transport studies and Raman spectroscopy as well as density functional theory (DFT) calculations, we report the direct observation of massless Dirac particles in monolayer graphene, providing a comprehensive mapping of their low-hole doped Dirac electron bands. The micrometric graphene flakes are oriented along two predominant directions rotated by 30° with respect to each other. The growth mode is attributed to the mechanism when small graphene “molecules” nucleate on the Ge(001) surface and it is found that hydrogen plays a significant role in this process.

Factors influencing epitaxial growth of three-dimensional Ge quantum dot crystals on pit-patterned Si substrate.

PubMed

Ma, Y J; Zhong, Z; Yang, X J; Fan, Y L; Jiang, Z M

2013-01-11

We investigated the molecular beam epitaxy growth of three-dimensional (3D) Ge quantum dot crystals (QDCs) on periodically pit-patterned Si substrates. A series of factors influencing the growth of QDCs were investigated in detail and the optimized growth conditions were found. The growth of the Si buffer layer and the first quantum dot (QD) layer play a key role in the growth of QDCs. The pit facet inclination angle decreased with increasing buffer layer thickness, and its optimized value was found to be around 21°, ensuring that all the QDs in the first layer nucleate within the pits. A large Ge deposition amount in the first QD layer favors strain build-up by QDs, size uniformity of QDs and hence periodicity of the strain distribution; a thin Si spacer layer favors strain correlation along the growth direction; both effects contribute to the vertical ordering of the QDCs. Results obtained by atomic force microscopy and cross-sectional transmission electron microscopy showed that 3D ordering was achieved in the Ge QDCs with the highest ever areal dot density of 1.2 × 10(10) cm(-2), and that the lateral and the vertical interdot spacing were ~10 and ~2.5 nm, respectively.

Understanding the growth mechanism of graphene on Ge/Si(001) surfaces

PubMed Central

Dabrowski, J.; Lippert, G.; Avila, J.; Baringhaus, J.; Colambo, I.; Dedkov, Yu S.; Herziger, F.; Lupina, G.; Maultzsch, J.; Schaffus, T.; Schroeder, T.; Kot, M.; Tegenkamp, C.; Vignaud, D.; Asensio, M.-C.

2016-01-01

The practical difficulties to use graphene in microelectronics and optoelectronics is that the available methods to grow graphene are not easily integrated in the mainstream technologies. A growth method that could overcome at least some of these problems is chemical vapour deposition (CVD) of graphene directly on semiconducting (Si or Ge) substrates. Here we report on the comparison of the CVD and molecular beam epitaxy (MBE) growth of graphene on the technologically relevant Ge(001)/Si(001) substrate from ethene (C2H4) precursor and describe the physical properties of the films as well as we discuss the surface reaction and diffusion processes that may be responsible for the observed behavior. Using nano angle resolved photoemission (nanoARPES) complemented by transport studies and Raman spectroscopy as well as density functional theory (DFT) calculations, we report the direct observation of massless Dirac particles in monolayer graphene, providing a comprehensive mapping of their low-hole doped Dirac electron bands. The micrometric graphene flakes are oriented along two predominant directions rotated by 30° with respect to each other. The growth mode is attributed to the mechanism when small graphene “molecules” nucleate on the Ge(001) surface and it is found that hydrogen plays a significant role in this process. PMID:27531322

Understanding the growth mechanism of graphene on Ge/Si(001) surfaces.

PubMed

Dabrowski, J; Lippert, G; Avila, J; Baringhaus, J; Colambo, I; Dedkov, Yu S; Herziger, F; Lupina, G; Maultzsch, J; Schaffus, T; Schroeder, T; Kot, M; Tegenkamp, C; Vignaud, D; Asensio, M-C

2016-08-17

The practical difficulties to use graphene in microelectronics and optoelectronics is that the available methods to grow graphene are not easily integrated in the mainstream technologies. A growth method that could overcome at least some of these problems is chemical vapour deposition (CVD) of graphene directly on semiconducting (Si or Ge) substrates. Here we report on the comparison of the CVD and molecular beam epitaxy (MBE) growth of graphene on the technologically relevant Ge(001)/Si(001) substrate from ethene (C2H4) precursor and describe the physical properties of the films as well as we discuss the surface reaction and diffusion processes that may be responsible for the observed behavior. Using nano angle resolved photoemission (nanoARPES) complemented by transport studies and Raman spectroscopy as well as density functional theory (DFT) calculations, we report the direct observation of massless Dirac particles in monolayer graphene, providing a comprehensive mapping of their low-hole doped Dirac electron bands. The micrometric graphene flakes are oriented along two predominant directions rotated by 30° with respect to each other. The growth mode is attributed to the mechanism when small graphene "molecules" nucleate on the Ge(001) surface and it is found that hydrogen plays a significant role in this process.

The reduction of critical H implantation dose for ion cut by incorporating B-doped SiGe/Si superlattice into Si substrate

NASA Astrophysics Data System (ADS)

Xue, Zhongying; Chen, Da; Jia, Pengfei; Wei, Xing; Di, Zengfeng; Zhang, Miao

2016-11-01

An approach to achieve Si or SiGe film exfoliation with as low as 3 × 1016/cm2 H implantation dose was investigated. Two intrinsic Si0.75Ge0.25/Si samples, merged with B-doped Si0.75Ge0.25 layer and B-doped Si0.75Ge0.25/Si superlattice (SL) layer respectively, were used to study the formation of crack after 3 × 1016/cm2 H implantation and annealing. For the sample into which B doped Si0.75Ge0.25 layer is incorporated, only few discrete cracks are observed along both sides of the B doped Si0.75Ge0.25 layer; on the contrary, a continuous (100) oriented crack is formed in the B-doped Si0.75Ge0.25/Si SL layer, which means ion cut can be achieved using this material with 3 × 1016/cm2 H implantation. As the SIMS profiles confirm that hydrogen tends to be trapped at B-doped SiGe/Si interface, the formation of continuous crack in SL layer can be ascribed to the more efficient hydrogen trapping by the multiple B-doped SiGe/Si interfaces.

Al203 thin films on Silicon and Germanium substrates for CMOS and flash memory applications

NASA Astrophysics Data System (ADS)

Gopalan, Sundararaman; Dutta, Shibesh; Ramesh, Sivaramakrishnan; Prathapan, Ragesh; Sreehari G., S.

2017-07-01

As scaling of device dimensions has continued, it has become necessary to replace traditional SiO2 with high dielectric constant materials in the conventional CMOS devices. In addition, use of metal gate electrodes and Germanium substrates may have to be used in order to address leakage and mobility issues. Al2O3 is one of the potential candidates both for CMOS and as a blocking dielectric for Flash memory applications owing to its low leakage. In this study, the effects of sputtering conditions and post-deposition annealing conditions on the electrical and reliability characteristics of MOS capacitors using Al2O3 films on Si and Ge substrates with Aluminium gate electrodes have been presented. It was observed that higher sputtering power resulted in larger flat-band voltage (Vfb) shifts, more hysteresis, higher interface state density (Dit) and a poorer reliability. Wit was also found that while a short duration high temperature annealing improves film characteristics, a long duration anneal even at 800C was found to be detrimental to MOS characteristics. Finally, the electronic conduction mechanism in Al2O3 films was also studied. It was observed that the conduction mechanism varied depending on the annealing condition, thickness of film and electric field.

Ultra-low specific contact resistivity (1.4 × 10-9 Ω.cm2) for metal contacts on in-situ Ga-doped Ge0.95Sn0.05 film

NASA Astrophysics Data System (ADS)

Wu, Ying; Luo, Sheng; Wang, Wei; Masudy-Panah, Saeid; Lei, Dian; Liang, Gengchiau; Gong, Xiao; Yeo, Yee-Chia

2017-12-01

A heavily Ga-doped Ge0.95Sn0.05 layer was grown on the Ge (100) substrate by molecular beam epitaxy (MBE), achieving an active doping concentration of 1.6 × 1020 cm-3 without the use of ion implantation and high temperature annealing that could cause Sn precipitation or surface segregation. An advanced nano-scale transfer length method was used to extract the specific contact resistivity ρc between the metal and the heavily doped p-Ge0.95Sn0.05 layer. By incorporating Sn into Ge and in-situ Ga doping during the MBE growth, an ultra-low ρc of 1.4 × 10-9 Ω.cm2 was achieved, which is 50% lower than the ρc of p+-Ge control and is also the lowest value obtained for metal/p-type semiconductor contacts.

Systematic study of Si-based GeSn photodiodes with 2.6 µm detector cutoff for short-wave infrared detection.

PubMed

Pham, Thach; Du, Wei; Tran, Huong; Margetis, Joe; Tolle, John; Sun, Greg; Soref, Richard A; Naseem, Hameed A; Li, Baohua; Yu, Shui-Qing

2016-03-07

Normal-incidence Ge 1-x Sn x photodiode detectors with Sn compositions of 7 and 10% have been demonstrated. Such detectors were based on Ge/Ge 1-x Sn x /Ge double heterostructures grown directly on a Si substrate via a chemical vapor deposition system. A temperature-dependence study of these detectors was conducted using both electrical and optical characterizations from 300 to 77 K. Spectral response up to 2.6 µm was achieved for a 10% Sn device at room temperature. The peak responsivity and specific detectivity (D*) were measured to be 0.3 A/W and 4 × 10 9 cmHz 1/2 W -1 at 1.55 µm, respectively. The spectral D* of a 7% Sn device at 77 K was only one order-of-magnitude lower than that of an extended-InGaAs photodiode operating in the same wavelength range, indicating the promising future of GeSn-based photodetectors.

Alloyed surfaces: New substrates for graphene growth

NASA Astrophysics Data System (ADS)

Tresca, C.; Verbitskiy, N. I.; Fedorov, A.; Grüneis, A.; Profeta, G.

2017-11-01

We report a systematic ab-initio density functional theory investigation of Ni(111) surface alloyed with elements of group IV (Si, Ge and Sn), demonstrating the possibility to use it to grow high quality graphene. Ni(111) surface represents an ideal substrate for graphene, due to its catalytic properties and perfect matching with the graphene lattice constant. However, Dirac bands of graphene growth on Ni(111) are completely destroyed due to the strong hybridization between carbon pz and Ni d orbitals. Group IV atoms, namely Si, Ge and Sn, once deposited on Ni(111) surface, form an ordered alloyed surface with √{ 3} ×√{ 3} -R30° reconstruction. We demonstrate that, at variance with the pure Ni(111) surface, alloyed surfaces effectively decouple graphene from the substrate, resulting unstrained due to the nearly perfect lattice matching and preserves linear Dirac bands without the strong hybridization with Ni d states. The proposed surfaces can be prepared before graphene growth without resorting on post-growth processes which necessarily alter the electronic and structural properties of graphene.

Ultra-wideband Ge-rich silicon germanium integrated Mach-Zehnder interferometer for mid-infrared spectroscopy.

PubMed

Vakarin, Vladyslav; Ramírez, Joan Manel; Frigerio, Jacopo; Ballabio, Andrea; Le Roux, Xavier; Liu, Qiankun; Bouville, David; Vivien, Laurent; Isella, Giovanni; Marris-Morini, Delphine

2017-09-01

This Letter explores the use of Ge-rich Si 0.2 Ge 0.8 waveguides on graded Si 1-x Ge x substrate for the demonstration of ultra-wideband photonic integrated circuits in the mid-infrared (mid-IR) wavelength range. We designed, fabricated, and characterized broadband Mach-Zehnder interferometers fully covering a range of 3 μm in the mid-IR band. The fabricated devices operate indistinctly in quasi-TE and quasi-TM polarizations, and have an extinction ratio higher than 10 dB over the entire operating wavelength range. The obtained results are in good correlation with theoretical predictions, while numerical simulations indicate that the device bandwidth can reach one octave with low additional losses. This Letter paves the way for further realization of mid-IR integrated spectrometers using low-index-contrast Si 1-x Ge x waveguides with high germanium concentration.

Local Anodic Oxidation of Thin GeO Films and Formation of Nanostructures Based on Them

NASA Astrophysics Data System (ADS)

Astankova, K. N.; Kozhukhov, A. S.; Azarov, I. A.; Gorokhov, E. B.; Sheglov, D. V.; Latyshev, A. V.

2018-04-01

The process of local anodic oxidation of thin GeO films has been studied using an atomic force microscope. The electron-probe microanalysis showed that oxidized areas of a GeO film were germanium dioxide. The effect of the voltage pulse duration applied to the probe-substrate system and the atmospheric humidity on the height of the oxide structures has been studied. The kinetics of the local anodic oxidation (LAO) in a semi-contact mode obeys the Cabrera-Mott model for large times. The initial growth rate of the oxide ( R 0) significantly increases and the time of starting the oxidation ( t 0) decreases as the atmospheric humidity increases by 20%, which is related to an increase in the concentration of oxygen-containing ions at the surface of the oxidized GeO film. It was shown that nanostructures in thin GeO layers can be formed by the LAO method.

Isolation and Characterization of a Geobacillus thermoleovorans Strain from an Ultra-Deep South African Gold Mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deflaun, Mary F.; Fredrickson, Jim K.; Dong, Hailiang

2007-03-08

A thermophilic, facultative bacterium was isolated from a depth of 3.1 km below ground surface in an ultradeep gold mine in South Africa. This isolate, designated GE-7, was cultivated from pH 8.0, 600C fissure water. GE-7 grows optimally at 650C, pH 6.5 on a wide range of carbon substrates including GE-7 is a long rod-shaped bacterium (4-6 µm long x 0.5 wide) with terminal endospores and flagella, in addition to O2, can also utilize nitrate as an electron acceptor. Phylogenetic analysis of GE-7 16S rDNA sequence revealed high sequence similarity with G. thermoleovorans DSM 5366T (99.6%), however, certain phenotypic characteristicsmore » of GE-7 were distinct from this and other strains of G. thermoleovorans previously described.« less

Ge nanocrystals embedded in ultrathin Si3N4 multilayers with SiO2 barriers

NASA Astrophysics Data System (ADS)

Bahariqushchi, R.; Gundogdu, Sinan; Aydinli, A.

2017-04-01

Multilayers of germanium nanocrystals (NCs) embedded in thin films of silicon nitride matrix separated with SiO2 barriers have been fabricated using plasma enhanced chemical vapor deposition (PECVD). SiGeN/SiO2 alternating bilayers have been grown on quartz and Si substrates followed by post annealing in Ar ambient from 600 to 900 °C. High resolution transmission electron microscopy (HRTEM) as well as Raman spectroscopy show good crystallinity of Ge confined to SiGeN layers in samples annealed at 900 °C. Strong compressive stress for SiGeN/SiO2 structures were observed through Raman spectroscopy. Size, as well as NC-NC distance were controlled along the growth direction for multilayer samples by varying the thickness of bilayers. Visible photoluminescence (PL) at 2.3 and 3.1 eV with NC size dependent intensity is observed and possible origin of PL is discussed.

III-V/Ge MOS device technologies for low power integrated systems

NASA Astrophysics Data System (ADS)

Takagi, S.; Noguchi, M.; Kim, M.; Kim, S.-H.; Chang, C.-Y.; Yokoyama, M.; Nishi, K.; Zhang, R.; Ke, M.; Takenaka, M.

2016-11-01

CMOS utilizing high mobility III-V/Ge channels on Si substrates is expected to be one of the promising devices for high performance and low power integrated systems in the future technology nodes, because of the enhanced carrier transport properties. In addition, Tunneling-FETs (TFETs) using Ge/III-V materials are regarded as one of the most important steep slope devices for the ultra-low power applications. In this paper, we address the device and process technologies of Ge/III-V MOSFETs and TFETs on the Si CMOS platform. The channel formation, source/drain (S/D) formation and gate stack engineering are introduced for satisfying the device requirements. The plasma post oxidation to form GeOx interfacial layers is a key gate stack technology for Ge CMOS. Also, direct wafer bonding of ultrathin body quantum well III-V-OI channels, combined with Tri-gate structures, realizes high performance III-V n-MOSFETs on Si. We also demonstrate planar-type InGaAs and Ge/strained SOI TFETs. The defect-less p+-n source junction formation with steep impurity profiles is a key for high performance TFET operation.

CGP 55398, a liposomal Ge(IV) phthalocyanine bearing two axially ligated cholesterol moieties: a new potential agent for photodynamic therapy of tumours.

PubMed Central

Segalla, A.; Milanesi, C.; Jori, G.; Capraro, H. G.; Isele, U.; Schieweck, K.

1994-01-01

Ge(IV) phthalocyanine (GePc) with two axially ligated cholesterol moieties was prepared by chemical synthesis and incorporated in a monomeric state into small unilamellar liposomes (CGP 55398). Upon photoexcitation with light wavelengths around its intense absorption peak at 680 nm, GePc shows an efficient photosensitising activity towards biological substrates through a mechanism which largely involves the intermediacy of singlet oxygen. GePc injected systemically into mice bearing an intramuscularly implanted MS-2 fibrosarcoma is quantitatively transferred to serum lipoproteins and localises in the tumour tissue with good efficiency: at 24 h post injection the GePc content in the tumour is 0.74 and 1.87 micrograms per g of tissue with a tumour/peritumoral ratio of 4.35 and 5.67 for injected doses of 0.76 and 1.52 mg kg-1 respectively. At this time the red-light irradiation of the GePc-loaded fibrosarcoma causes a fast and massive tumour necrosis involving both malignant cells and blood vessels. Images Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 PMID:8180009

Characterization of strain relaxation behavior in Si1- x Ge x epitaxial layers by dry oxidation

NASA Astrophysics Data System (ADS)

Jang, Hyunchul; Kim, Byongju; Koo, Sangmo; Park, Seran; Ko, Dae-Hong

2017-11-01

We fabricated fully strained Si0.77Ge0.23 epitaxial layers on Si substrates and investigated their strain relaxation behaviors under dry oxidation and the effect of oxidation temperatures and times. After the oxidation process, a Ge-rich layer was formed between the oxide and the remaining Si0.77Ge0.23 layer. Using reciprocal space mapping measurements, we confirmed that the strain of the Si0.77Ge0.23 layers was efficiently relaxed after oxidation, with a maximum relaxation value of 70% after oxidation at 850 °C for 120 min. The surface of Si0.77Ge0.23 layer after strain relaxation by dry oxidation was smoother than a thick Si0.77Ge0.23 layer, which achieved a similar strain relaxation value by increasing the film thickness. Additionally, N2 annealing was performed in order to compare its effect on the relaxation compared to dry oxidation and to identify relaxation mechanisms, other than the thermally driven ones, occurring during dry oxidation.

Systematic study of GeSn heterostructure-based light-emitting diodes towards mid-infrared applications

NASA Astrophysics Data System (ADS)

Zhou, Yiyin; Dou, Wei; Du, Wei; Pham, Thach; Ghetmiri, Seyed Amir; Al-Kabi, Sattar; Mosleh, Aboozar; Alher, Murtadha; Margetis, Joe; Tolle, John; Sun, Greg; Soref, Richard; Li, Baohua; Mortazavi, Mansour; Naseem, Hameed; Yu, Shui-Qing

2016-07-01

Temperature-dependent characteristics of GeSn light-emitting diodes with Sn composition up to 9.2% have been systematically studied. Such diodes were based on Ge/GeSn/Ge double heterostructures (DHS) that were grown directly on a Si substrate via a chemical vapor deposition system. Both photoluminescence and electroluminescence spectra have been characterized at temperatures from 300 to 77 K. Based on our theoretical calculation, all GeSn alloys in this study are indirect bandgap materials. However, due to the small energy separation between direct and indirect bandgap, and the fact that radiative recombination rate greater than non-radiative, the emissions are mainly from the direct Γ-valley to valence band transitions. The electroluminescence emissions under current injection levels from 102 to 357 A/cm2 were investigated at 300 K. The monotonic increase of the integrated electroluminescence intensity was observed for each sample. Moreover, the electronic band structures of the DHS were discussed. Despite the indirect GeSn bandgap owing to the compressive strain, type-I band alignment was achieved with the barrier heights ranging from 11 to 47 meV.

Strong quantum-confined Stark effect in a lattice-matched GeSiSn/GeSn multi-quantum-well structure

NASA Astrophysics Data System (ADS)

Peng, Ruizhi; Chunfuzhang; Han, Genquan; Hao, Yue

2017-06-01

This paper presents modeling and simulation of a multiple quantum well structure formed with Ge0.95Sn0.05 quantum wells separated by Ge0.51Si0.35Sn0.14 barriers for the applications. These alloy compositions are chosen to satisfy two conditions simultaneously: type-I band alignment between Ge0.95Sn0.05/Ge0.51Si0.35Sn0.14 and a lattice match between wells and barriers. This lattice match ensures that the strain-free structure can be grown upon a relaxed Ge0.51Si0.35Sn0.14 buffer on a silicon substrate - a CMOS compatible process. A electro-absorption modulator with the Ge0.95Sn0.05/Ge0.51Si0.35Sn0.14 multiple quantum well structure based on quantum-confined Stark effect(QCSE) is demonstrated in theory. The energy band diagrams of the GeSiSn/GeSn multi-quantum-well structure at 0 and 0.5V bias are calculated, respectively. And the corresponding absorption coefficients as a function of cut-off energy for this multiple quantum well structure at 0 and 0.5Vbias are also obtained, respectively. The reduction of cut-off energy is observed with the applying of the external electric field, indicating a strong QCSE in the structure.

A Facile Method to In-Situ Synthesize Porous Ni₂GeO₄ Nano-Sheets on Nickel Foam as Advanced Anode Electrodes for Li-Ion Batteries.

PubMed

Ma, Delong; Shi, Xiaomin; Hu, Anming

2016-11-19

A strategy for growth of porous Ni₂GeO₄ nanosheets on conductive nickel (Ni) foam with robust adhesion as a high-performance electrode for Li-ion batteries is proposed and realized, through a facile two-step method. It involves the low temperature hydro-thermal synthesis of bimetallic (Ni, Ge) hydroxide nanosheets precursor on Ni foam substrates and subsequent thermal transformation to porous Ni₂GeO₄ nanosheets. The as-prepared Ni₂GeO₄ nanosheets possess many interparticle mesopores with a size range from 5 to 15 nm. The hierarchical structure of porous Ni₂GeO₄ nanosheets supported by Ni foam promises fast electron and ion transport, large electroactive surface area, and excellent structural stability. The efficacy of the specially designed structure is demonstrated by the superior electrochemical performance of the generated Ni₂GeO₄ nanosheets including a high capacity of 1.8 mA·h·cm -2 at a current density of 50 μA·cm -2 , good cycle stability, and high power capability at room temperature. Because of simple conditions, this fabrication strategy may be easily extended to other mixed metal oxides (M x GeO y ).

Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ceylan, Abdullah, E-mail: aceylanabd@yahoo.com; Ozcan, Yusuf; Orujalipoor, Ilghar

2016-06-07

In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactivemore » growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron microscopy observations but also provide additional information on the large scale size and shape distribution of the nanostructured components.« less

Raman and photoluminescence spectroscopy of SiGe layer evolution on Si(100) induced by dewetting

NASA Astrophysics Data System (ADS)

Shklyaev, A. A.; Volodin, V. A.; Stoffel, M.; Rinnert, H.; Vergnat, M.

2018-01-01

High temperature annealing of thick (40-100 nm) Ge layers deposited on Si(100) at ˜400 °C leads to the formation of continuous films prior to their transformation into porous-like films due to dewetting. The evolution of Si-Ge composition, lattice strain, and surface morphology caused by dewetting is analyzed using scanning electron microscopy, Raman, and photoluminescence (PL) spectroscopies. The Raman data reveal that the transformation from the continuous to porous film proceeds through strong Si-Ge interdiffusion, reducing the Ge content from 60% to about 20%, and changing the stress from compressive to tensile. We expect that Ge atoms migrate into the Si substrate occupying interstitial sites and providing thereby the compensation of the lattice mismatch. Annealing generates only one type of radiative recombination centers in SiGe resulting in a PL peak located at about 0.7 and 0.8 eV for continuous and porous film areas, respectively. Since annealing leads to the propagation of threading dislocations through the SiGe/Si interface, we can tentatively associate the observed PL peak to the well-known dislocation-related D1 band.

Photoluminescence of phosphorus atomic layer doped Ge grown on Si

NASA Astrophysics Data System (ADS)

Yamamoto, Yuji; Nien, Li-Wei; Capellini, Giovanni; Virgilio, Michele; Costina, Ioan; Schubert, Markus Andreas; Seifert, Winfried; Srinivasan, Ashwyn; Loo, Roger; Scappucci, Giordano; Sabbagh, Diego; Hesse, Anne; Murota, Junichi; Schroeder, Thomas; Tillack, Bernd

2017-10-01

Improvement of the photoluminescence (PL) of Phosphorus (P) doped Ge by P atomic layer doping (ALD) is investigated. Fifty P delta layers of 8 × 1013 cm-2 separated by 4 nm Ge spacer are selectively deposited at 300 °C on a 700 nm thick P-doped Ge buffer layer of 1.4 × 1019 cm-3 on SiO2 structured Si (100) substrate. A high P concentration region of 1.6 × 1020 cm-3 with abrupt P delta profiles is formed by the P-ALD process. Compared to the P-doped Ge buffer layer, a reduced PL intensity is observed, which might be caused by a higher density of point defects in the P delta doped Ge layer. The peak position is shifted by ˜0.1 eV towards lower energy, indicating an increased active carrier concentration in the P-delta doped Ge layer. By introducing annealing at 400 °C to 500 °C after each Ge spacer deposition, P desorption and diffusion is observed resulting in relatively uniform P profiles of ˜2 × 1019 cm-3. Increased PL intensity and red shift of the PL peak are observed due to improved crystallinity and higher active P concentration.

Control of Ge1-x-ySixSny layer lattice constant for energy band alignment in Ge1-xSnx/Ge1-x-ySixSny heterostructures

NASA Astrophysics Data System (ADS)

Fukuda, Masahiro; Watanabe, Kazuhiro; Sakashita, Mitsuo; Kurosawa, Masashi; Nakatsuka, Osamu; Zaima, Shigeaki

2017-10-01

The energy band alignment of Ge1-xSnx/Ge1-x-ySixSny heterostructures was investigated, and control of the valence band offset at the Ge1-xSnx/Ge1-x-ySixSny heterointerface was achieved by controlling the Si and Sn contents in the Ge1-x-ySixSny layer. The valence band offset in the Ge0.902Sn0.098/Ge0.41Si0.50Sn0.09 heterostructure was evaluated to be as high as 330 meV, and its conduction band offset was estimated to be 150 meV by considering the energy bandgap calculated from the theoretical prediction. In addition, the formation of the strain-relaxed Ge1-x-ySixSny layer was examined and the crystalline structure was characterized. The epitaxial growth of a strain-relaxed Ge0.64Si0.21Sn0.15 layer with the degree of strain relaxation of 55% was examined using a virtual Ge substrate. Moreover, enhancement of the strain relaxation was demonstrated by post-deposition annealing, where a degree of strain relaxation of 70% was achieved after annealing at 400 °C. These results indicate the possibility for enhancing the indirect-direct crossover with a strained and high-Sn-content Ge1-xSnx layer on a strain-relaxed Ge1-x-ySixSny layer, realizing preferable carrier confinement by type-I energy band alignment with high conduction and valence band offsets.

Surface electronic states of low-temperature H-plasma-exposed Ge(100)

NASA Astrophysics Data System (ADS)

Cho, Jaewon; Nemanich, R. J.

1992-11-01

The surface of low-temperature H-plasma-cleaned Ge(100) was studied by angle-resolved UV-photoemission spectroscopy and low-energy electron diffraction (LEED). The surface was prepared by an ex situ preclean followed by an in situ H-plasma exposure at a substrate temperature of 150-300 °C. Auger-electron spectroscopy indicated that the in situ H-plasma clean removed the surface contaminants (carbon and oxygen) from the Ge(100) surface. The LEED pattern varied from a 1×1 to a sharp 2×1, as the substrate temperature was increased. The H-induced surface state was identified at ~5.6 eV below EF, which was believed to be mainly due to the ordered or disordered monohydride phases. The annealing dependence of the spectra showed that the hydride started to dissociate at a temperature of 190 °C, and the dangling-bond surface state was identified. A spectral shift upon annealing indicated that the H-terminated surfaces were unpinned. After the H-plasma clean at 300 °C the dangling-bond surface state was also observed directly with no evidence of H-induced states.

Laser ultrasonic characterization of membranes for use as micro-electronic mechanical systems (MEMS)

NASA Astrophysics Data System (ADS)

Edwards, R. S.; Zhou, L. Q.; Pearce, M. J.; Prince, R. G.; Colston, G.; Myronov, M.; Leadley, D. R.; Trushkevych, O.

2017-02-01

Germanium (Ge) on Silicon (Si) has the potential to produce a wide variety of devices, including sensors, solar cells and transistors. Modification of these materials so that a suspended membrane layer is formed, through removing regions of the Si substrate, offers the potential for sensors with a more rapid response and higher sensitivity. Such membranes are a very simple micro-electronic mechanical system (MEMS). It is essential to ensure that the membranes are robust against shock and vibration, with well-characterised resonant frequencies, prior to any practical application. We present work using laser interferometry to characterise the resonant modes of membranes produced from Ge or silicon carbide (SiC) on a Si substrate, with the membranes typically having around 1 mm lateral dimensions. Two dimensional scanning of the sample enables visualisation of each mode. The stress measured from the resonant frequencies agrees well with that calculated from the growth conditions. SiC provides a more robust platform for electronics, while Ge offers better resonant properties. This offers a potential technique for characterising production quality or lifetime testing for the MEMS produced.

Tiered deposition of sub-5 nm ferroelectric Hf1-xZrxO2 films on metal and semiconductor substrates

NASA Astrophysics Data System (ADS)

Walters, Glen; Shekhawat, Aniruddh; Rudawski, Nicholas G.; Moghaddam, Saeed; Nishida, Toshikazu

2018-05-01

Using a tiered deposition approach, Hf1-xZrxO2 (HZO) films with varying atomic layer deposition (ALD) cycles from 36 to 52 cycles were grown on Ge, Ir, and TiN substrates in single runs and annealed at 500 °C. 40 ALD cycle films grown on Ir exhibit a switched polarization (Psw) of 13 μC/cm2, while those grown on Ge and TiN did not exhibit measurable Psw values until 44 and 52 ALD cycles, respectively. High-resolution cross-sectional transmission electron microscopy confirmed these results; the ferroelectric films are crystalline with defined lattice fringes, while non-ferroelectric films remain amorphous. 52 ALD cycle 1:1 HZO grown on Ge had the highest Psw of all the films fabricated at 39 μC/cm2, while the 1:1 HZO grown on TiN displayed continuous wake-up and no fatigue up to 1010 cycles with the Psw increasing from <1 μC/cm2 to 21 μC/cm2.

Electrical and Structural Analysis on the Formation of n-type Junction in Germanium

NASA Astrophysics Data System (ADS)

Aziz, Umar Abdul; Nadhirah Mohamad Rashid, Nur; Rahmah Aid, Siti; Centeno, Anthony; Ikenoue, Hiroshi; Xie, Fang

2017-05-01

Germanium (Ge) has re-emerged as a potential candidate to replace silicon (Si) as a substrate, due to its higher carrier mobility properties that are the key point for the realization of devices high drive current. However, the fabrication process of Ge is confronted with many problems such as low dopant electrical activation and the utilization of heavy n-type dopant atoms during ion implantation. These problems result in more damage and defects that can affect dopant activation. This paper reports the electrical and structural analysis on the formation of n-type junction in Ge substrate by ion implantation, followed by excimer laser annealing (ELA) using KrF laser. ELA parameters such as laser fluences were varied from 100 - 2000 mJ/cm2 and shot number between 1 - 1000 to obtain the optimized parameter of ELA with a high degree of damage and defect removal. Low resistance with a high degree of crystallinity is obtained for the samples annealed with less than five shot number. Higher shot number with high laser fluence, shows a high degree of ablation damage.

Structural and chemical ordering of Heusler C o x M n y G e z epitaxial films on Ge (111): Quantitative study using traditional and anomalous x-ray diffraction techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Collins, B. A.; Chu, Y. S.; He, L.

2015-12-14

Epitaxial films of C o x M n y G e z grown on Ge (111) substrates by molecular-beam-epitaxy techniques have been investigated as a continuous function of composition using combinatorial synchrotron x-ray diffraction (XRD) and x-ray fluorescence (XRF) spectroscopy techniques. A high-resolution ternary epitaxial phase diagram is obtained, revealing a small number of structural phases stabilized over large compositional regions. Ordering of the constituent elements in the compositional region near the full Heusler alloy C o 2 MnGe has been examined in detail using both traditional XRD and a new multiple-edge anomalous diffraction (MEAD) technique. Multiple-edge anomalous diffraction involvesmore » analyzing the energy dependence of multiple reflections across each constituent absorption edge in order to detect and quantify the elemental distribution of occupation in specific lattice sites. Results of this paper show that structural and chemical ordering are very sensitive to the Co : Mn atomic ratio, such that the ordering is the highest at an atomic ratio of 2 but significantly reduced even a few percent off this ratio. The in-plane lattice is nearly coherent with that of the Ge substrate, while the approximately 2% lattice mismatch is accommodated by the out-of-plane tetragonal strain. The quantitative MEAD analysis further reveals no detectable amount (<0.5%) of Co-Mn site swapping, but instead high levels (26%) of Mn-Ge site swapping. Increasing Ge concentration above the Heusler stoichiometry ( C o 0.5 M n 0.25 G e 0.25 ) is shown to correlate with increased lattice vacancies, antisites, and stacking faults, but reduced lattice relaxation. The highest degree of chemical ordering is observed off the Heusler stoichiometry with a Ge enrichment of 5 at.%.« less

Innovative Ge Quantum Dot Functional Sensing and Metrology Devices

DTIC Science & Technology

2017-08-21

information latency and power consumption . In contrast, optical interconnects have shown tremendous promise for replacing electrical wires thanks to...single oxidation step of Si0.85Ge0.15 nano-pillars patterned over a buffer layer of Si3N4 on top of the n-Si substrate. During the high- temperature ...exquisitely-controlled dynamic balance between the fluxes of oxygen and silicon interstitials. Results and Discussion: 1. Self-organized, gate

Contradictory nature of Co doping in ferroelectric BaTi O 3

DOE PAGES

Ponath, Patrick; O’Hara, Andrew; Cao, Hai-Xia; ...

2016-11-11

The growth of Co-substituted BaTiO 3 (BTO) films on Ge(001) substrates by molecular beam epitaxy is demonstrated in this paper. Energy-dispersive x-ray spectroscopy and transmission electron microscopy images confirm the uniform Co distribution. However, no evidence of magnetic ordering is observed in samples grown for Co concentrations between 2% and 40%. Piezoresponse force microscopy measurements show that a 5% Co-substituted BTO sample exhibits ferroelectric behavior. First-principles calculations indicate that while Co atoms couple ferromagnetically in the absence of oxygen vacancies, the occurrence of oxygen vacancies leads to locally antiferromagnetically coupled complexes with relatively strong spin coupling. Finally, the presence ofmore » a significant amount of oxygen vacancies is suggested by x-ray photoelectron spectroscopy measurements.« less

Quantum ballistic transport in strained epitaxial germanium

NASA Astrophysics Data System (ADS)

Gul, Y.; Holmes, S. N.; Newton, P. J.; Ellis, D. J. P.; Morrison, C.; Pepper, M.; Barnes, C. H. W.; Myronov, M.

2017-12-01

Large scale fabrication using Complementary Metal Oxide Semiconductor compatible technology of semiconductor nanostructures that operate on the principles of quantum transport is an exciting possibility now due to the recent development of ultra-high mobility hole gases in epitaxial germanium grown on standard silicon substrates. We present here a ballistic transport study of patterned surface gates on strained Ge quantum wells with SiGe barriers, which confirms the quantum characteristics of the Ge heavy hole valence band structure in 1-dimension. Quantised conductance at multiples of 2e2/h is a universal feature of hole transport in Ge up to 10 × (2e2/h). The behaviour of ballistic plateaus with finite source-drain bias and applied magnetic field is elucidated. In addition, a reordering of the ground state is observed.

Enhancing elastic stress relaxation in SiGe/Si heterostructures by Si pillar necking

NASA Astrophysics Data System (ADS)

Isa, F.; Salvalaglio, M.; Arroyo Rojas Dasilva, Y.; Jung, A.; Isella, G.; Erni, R.; Timotijevic, B.; Niedermann, P.; Gröning, P.; Montalenti, F.; von Känel, H.

2016-10-01

We demonstrate that the elastic stress relaxation mechanism in micrometre-sized, highly mismatched heterostructures may be enhanced by employing patterned substrates in the form of necked pillars, resulting in a significant reduction of the dislocation density. Compositionally graded Si1-xGex crystals were grown by low energy plasma enhanced chemical vapour deposition, resulting in tens of micrometres tall, three-dimensional heterostructures. The patterned Si(001) substrates consist of micrometre-sized Si pillars either with the vertical {110} or isotropically under-etched sidewalls resulting in narrow necks. The structural properties of these heterostructures were investigated by defect etching and transmission electron microscopy. We show that the dislocation density, and hence the competition between elastic and plastic stress relaxation, is highly influenced by the shape of the substrate necks and their proximity to the mismatched epitaxial material. The SiGe dislocation density increases monotonically with the crystal width but is significantly reduced by the substrate under-etching. The drop in dislocation density is interpreted as a direct effect of the enhanced compliance of the under-etched Si pillars, as confirmed by the three-dimensional finite element method simulations of the elastic energy distribution.

Shaping Ge islands on Si(001) surfaces with misorientation angle.

PubMed

Persichetti, L; Sgarlata, A; Fanfoni, M; Balzarotti, A

2010-01-22

A complete description of Ge growth on vicinal Si(001) surfaces in the angular miscut range 0 degrees -8 degrees is presented. The key role of substrate vicinality is clarified from the very early stages of Ge deposition up to the nucleation of 3D islands. By a systematic scanning tunneling microscopy investigation we are able to explain the competition between step-flow growth and 2D nucleation and the progressive elongation of the 3D islands along the miscut direction [110]. Using finite element calculations, we find a strict correlation between the morphological evolution and the energetic factors which govern the {105} faceting at atomic scale.

Exceptional cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si heterostructures

NASA Astrophysics Data System (ADS)

Chen, Da; Wang, Dadi; Chang, Yongwei; Li, Ya; Ding, Rui; Li, Jiurong; Chen, Xiao; Wang, Gang; Guo, Qinglei

2018-01-01

The cracking behavior in H-implanted Si/B-doped Si0.70Ge0.30/Si structures after thermal annealing was investigated. The crack formation position is found to closely correlate with the thickness of the buried Si0.70Ge0.30 layer. For H-implanted Si containing a buried 3-nm-thick B-doped Si0.70Ge0.30 layer, localized continuous cracking occurs at the interfaces on both sides of the Si0.70Ge0.30 interlayer. Once the thickness of the buried Si0.70Ge0.30 layer increases to 15 and 70 nm, however, a continuous sharp crack is individually observed along the interface between the Si substrate and the B-doped Si0.70Ge0.30 interlayer. We attribute this exceptional cracking behavior to the existence of shear stress on both sides of the buried Si0.70Ge0.30 layer and the subsequent trapping of hydrogen, which leads to a crack in a well-controlled manner. This work may pave the way for high-quality Si or SiGe membrane transfer in a feasible manner, thus expediting its potential applications to ultrathin silicon-on-insulator (SOI) or silicon-germanium-on-insulator (SGOI) production.

Dense Ge nanocrystals embedded in TiO2 with exponentially increased photoconduction by field effect.

PubMed

Lepadatu, A-M; Slav, A; Palade, C; Dascalescu, I; Enculescu, M; Iftimie, S; Lazanu, S; Teodorescu, V S; Ciurea, M L; Stoica, T

2018-03-20

Si and Ge nanocrystals in oxides are of a large interest for photo-effect applications due to the fine-tuning of the optical bandgap by quantum confinement in nanocrystals. In this work, dense Ge nanocrystals suitable for enhanced photoconduction were fabricated from 60% Ge in TiO 2 amorphous layers by low temperature rapid thermal annealing at 550 °C. An exponential increase of the photocurrent with the applied voltage was observed in coplanar structure of Ge nanocrystals composite films deposited on oxidized Si wafers. The behaviour was explained by field effect control of the Fermi level at the Ge nanocrystals-TiO 2 layer/substrate interfaces. The blue-shift of the absorption gap from bulk Ge value to 1.14 eV was evidenced in both photocurrent spectra and optical reflection-transmission experiments, in good agreement with quantum confinement induced bandgap broadening in Ge nanocrystal with sizes of about 5 nm as found from HRTEM and XRD investigations. A nonmonotonic spectral dependence of the refractive index is associated to the Ge nanocrystals formation. The nanocrystal morphology is also in good agreement with the Coulomb gap hopping mechanism of T -1/2 -type explaining the temperature dependence of the dark conduction.

Room Temperature Ferromagnetic Mn:Ge(001)

PubMed Central

Lungu, George Adrian; Stoflea, Laura Elena; Tanase, Liviu Cristian; Bucur, Ioana Cristina; Răduţoiu, Nicoleta; Vasiliu, Florin; Mercioniu, Ionel; Kuncser, Victor; Teodorescu, Cristian-Mihail

2014-01-01

We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001), heated at relatively high temperature (starting with 250 °C). The samples were characterized by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID), and magneto-optical Kerr effect (MOKE). Samples deposited at relatively elevated temperature (350 °C) exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001) crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm) deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001). The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed. PMID:28788444

Low-temperature amorphous boron nitride on Si0.7Ge0.3(001), Cu, and HOPG from sequential exposures of N2H4 and BCl3

NASA Astrophysics Data System (ADS)

Wolf, Steven; Edmonds, Mary; Sardashti, Kasra; Clemons, Max; Park, Jun Hong; Yoshida, Naomi; Dong, Lin; Nemani, Srinivas; Yieh, Ellie; Holmes, Russell; Alvarez, Daniel; Kummel, Andrew C.

2018-05-01

Low-temperature sequential exposures of N2H4 and BCl3 have been performed on Si0.3Ge0.7(001), Cu, and HOPG surfaces at 350 °C. A novel BN ALD process has been achieved on Si0.3Ge0.7(001) with 60 cycles of BN ALD producing a uniform, pinhole-free thin film with low contamination, as characterized with XPS and AFM. On Cu and Si0.3Ge0.7(001), XPS spectra indicated a near stoichiometric BN film. While AFM imaging indicated the deposition on Cu yielded nanometer-scale etching, conformal deposition was observed on Si0.3Ge0.7(001). The BN ALD also nucleated on inert HOPG via step edges. In situ STM imaging showed that cyclic exposures at 350 °C were able to decorate step edges with features ∼2 nm tall and ∼200 nm wide, indicating the propensity for BN to grow in the planar direction. The N2H4 and BCl3 ALD allows for the deposition of low oxygen, low carbon films, but to avoid etching, the growth should be nucleated by N2H4, since exposure to BCl3 can result in the formation of volatile Cl-containing surface species on many substrates. Therefore, the formation of a stable surface nitride prior to BCl3 exposure is necessary to prevent formation and desorption of volatile species from the substrate.

Vertical nanowire heterojunction devices based on a clean Si/Ge interface.

PubMed

Chen, Lin; Fung, Wayne Y; Lu, Wei

2013-01-01

Different vertical nanowire heterojunction devices were fabricated and tested based on vertical Ge nanowires grown epitaxially at low temperatures on (111) Si substrates with a sharp and clean Si/Ge interface. The nearly ideal Si/Ge heterojuctions with controlled and abrupt doping profiles were verified through material analysis and electrical characterizations. In the nSi/pGe heterojunction diode, an ideality factor of 1.16, subpicoampere reverse saturation current, and rectifying ratio of 10(6) were obtained, while the n+Si/p+Ge structure leads to Esaki tunnel diodes with a high peak tunneling current of 4.57 kA/cm(2) and negative differential resistance at room temperature. The large valence band discontinuity between the Ge and Si in the nanowire heterojunctions was further verified in the p+Si/pGe structure, which shows a rectifying behavior instead of an Ohmic contact and raises an important issue in making Ohmic contacts to heterogeneously integrated materials. A raised Si/Ge structure was further developed using a self-aligned etch process, allowing greater freedom in device design for applications such as the tunneling field-effect transistor (TFET). All measurement data can be well-explained and fitted with theoretical models with known bulk properties, suggesting that the Si/Ge nanowire system offers a very clean heterojunction interface with low defect density, and holds great potential as a platform for future high-density and high-performance electronics.

Al{sub 2}O{sub 3}/GeO{sub x}/Ge gate stacks with low interface trap density fabricated by electron cyclotron resonance plasma postoxidation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, R.; Iwasaki, T.; Taoka, N.

2011-03-14

An electron cyclotron resonance (ECR) plasma postoxidation method has been employed for forming Al{sub 2}O{sub 3}/GeO{sub x}/Ge metal-oxide-semiconductor (MOS) structures. X-ray photoelectron spectroscopy and transmission electron microscope characterizations have revealed that a GeO{sub x} layer is formed beneath the Al{sub 2}O{sub 3} capping layer by exposing the Al{sub 2}O{sub 3}/Ge structures to ECR oxygen plasma. The interface trap density (D{sub it}) of Au/Al{sub 2}O{sub 3}/GeO{sub x}/Ge MOS capacitors is found to be significantly suppressed down to lower than 10{sup 11} cm{sup -2} eV{sup -1}. Especially, a plasma postoxidation time of as short as 10 s is sufficient to reduce D{submore » it} with maintaining the equivalent oxide thickness (EOT). As a result, the minimum D{sub it} values and EOT of 5x10{sup 10} cm{sup -2} eV{sup -1} and 1.67 nm, and 6x10{sup 10} cm{sup -2} eV{sup -1} and 1.83 nm have been realized for Al{sub 2}O{sub 3}/GeO{sub x}/Ge MOS structures with p- and n-type substrates, respectively.« less

MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection

DTIC Science & Technology

2012-09-01

MSM) photodectors fabricated using black silicon-germanium on silicon substrate (Si1–xGex//Si) for I-V, optical response, external quantum ...material for Si for many applications in low-power and high-speed semiconductor device technologies (4, 5). It is a promising material for quantum well ...MSM-Metal Semiconductor Metal Photo-detector Using Black Silicon Germanium (SiGe) for Extended Wavelength Near Infrared Detection by Fred

Formation of the low-resistivity compound Cu{sub 3}Ge by low-temperature treatment in an atomic hydrogen flux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erofeev, E. V., E-mail: erofeev@micran.ru; Kazimirov, A. I.; Fedin, I. V.

The systematic features of the formation of the low-resistivity compound Cu{sub 3}Ge by low-temperature treatment of a Cu/Ge two-layer system in an atomic hydrogen flux are studied. The Cu/Ge two-layer system is deposited onto an i-GaAs substrate. Treatment of the Cu/Ge/i-GaAs system, in which the layer thicknesses are, correspondingly, 122 and 78 nm, in atomic hydrogen with a flux density of 10{sup 15} at cm{sup 2} s{sup –1} for 2.5–10 min at room temperature induces the interdiffusion of Cu and Ge, with the formation of a polycrystalline film containing the stoichiometric Cu{sub 3}Ge phase. The film consists of vertically orientedmore » grains 100–150 nm in size and exhibits a minimum resistivity of 4.5 µΩ cm. Variations in the time of treatment of the Cu/Ge/i-GaAs samples in atomic hydrogen affect the Cu and Ge depth distribution, the phase composition of the films, and their resistivity. Experimental observation of the synthesis of the Cu{sub 3}Ge compound at room temperature suggests that treatment in atomic hydrogen has a stimulating effect on both the diffusion of Cu and Ge and the chemical reaction of Cu{sub 3}Ge-compound formation. These processes can be activated by the energy released upon the recombination of hydrogen atoms adsorbed at the surface of the Cu/Ge/i-GaAs sample.« less

Room Temperature Ferromagnetic Mn:Ge(001).

PubMed

Lungu, George Adrian; Stoflea, Laura Elena; Tanase, Liviu Cristian; Bucur, Ioana Cristina; Răduţoiu, Nicoleta; Vasiliu, Florin; Mercioniu, Ionel; Kuncser, Victor; Teodorescu, Cristian-Mihail

2013-12-27

We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001), heated at relatively high temperature (starting with 250 °C). The samples were characterized by low energy electron diffraction (LEED), scanning tunneling microscopy (STM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), superconducting quantum interference device (SQUID), and magneto-optical Kerr effect (MOKE). Samples deposited at relatively elevated temperature (350 °C) exhibited the formation of ~5-8 nm diameter Mn₅Ge₃ and Mn 11 Ge₈ agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe ~2.5 phase, or manganese diluted into the Ge(001) crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm) deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge-Ge dimers on Ge(001). The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.

Characterization and Fabrication of High k dielectric-High Mobility Channel Transistors

NASA Astrophysics Data System (ADS)

Sun, Xiao

As the conventional scaling of Si-based MOSFETs would bring negligible or even negative merits for IC's beyond the 7-nm CMOS technology node, many perceive the use of high-mobility channels to be one of the most likely principle changes, in order to achieve higher performance and lower power. However, interface and oxide traps have become a major obstacle for high-mobility semiconductors (such as Ge, InGaAs, GaSb, GaN...) to replace Si CMOS technology. In this thesis, the distinct properties of the traps in the high-k dielectric/high-mobility substrate system is discussed, as well as the challenges to characterize and passivate them. By modifying certain conventional gate admittance methods, both the fast and slow traps in Ge MOS gate stacks is investigated. In addition, a novel ac-transconductance method originated at Yale is introduced and demonstrated with several advanced transistors provided by collaborating groups, such as ultra-thin-body & box SO1 MOSFETs (CEA-LETI), InGaAs MOSFETs (IMEC, UT Austin, Purdue), and GaN MOS-HEMT (MIT). By use of the aforementioned characterization techniques, several effective passivation techniques on high mobility substrates (Ge, InGaAs, GaSb, GeSn, etc.) are evaluated, including a novel Ba sub-monolayer passivation of Ge surface. The key factors that need to be considered in passivating high mobility substrates are revealed. The techniques that we have established for characterizing traps in advanced field-effect transistors, as well as the knowledge gained about these traps by the use of these techniques, have been applied to the study of ionizing radiation effects in high-mobility-channel transistors, because it is very important to understand such effects as these devices are likely to be exposed to radiation-harsh environments, such as in outer space, nuclear plants, and during X-ray or UHV lithography. In this thesis, the total ionizing dose (TD) radiation effects of InGaAs-based MOSFETs and GaN-based MOS-HEMT are studied, and the results help to reveal the underlying mechanisms and inspire ideas for minimizing the TID radiation effects.

Agglomeration dynamics of germanium islands on a silicon oxide substrate: A grazing incidence small-angle x-ray scattering study

NASA Astrophysics Data System (ADS)

Cheynis, F.; Leroy, F.; Passanante, T.; Müller, P.

2013-04-01

Grazing-incidence small-angle X-ray scattering (GISAXS) and grazing-incidence X-ray diffraction techniques are used to characterise the thermally induced solid-state dewetting of Ge(001) thin films leading to the formation of 3D Ge islands. A quantitative analysis based on the Kolmogorov-Johnson-Mehl-Avrami model is derived. The main physical parameters controlling the dewetting (activation energy and kinetic pre-factors) are determined. Assuming that the dewetting is driven by surface/interface minimisation and limited by surface diffusion, the Ge surface self-diffusion reads as Ds ,0c0 e-Ea/(kBT) ˜3×1018 e-2.6±0.3eV/(kBT) nm2/s. GISAXS technique enables to reconstruct the mean Ge-island shape, including facets.

Modified Stranski-Krastanov growth in Ge/Si heterostructures via nanostenciled pulsed laser deposition.

PubMed

MacLeod, J M; Cojocaru, C V; Ratto, F; Harnagea, C; Bernardi, A; Alonso, M I; Rosei, F

2012-02-17

The combination of nanostenciling with pulsed laser deposition (PLD) provides a flexible, fast approach for patterning the growth of Ge on Si. Within each stencilled site, the morphological evolution of the Ge structures with deposition follows a modified Stranski-Krastanov (SK) growth mode. By systematically varying the PLD parameters (laser repetition rate and number of pulses) on two different substrate orientations (111 and 100), we have observed corresponding changes in growth morphology, strain and elemental composition using scanning electron microscopy, atomic force microscopy and μ-Raman spectroscopy. The growth behaviour is well predicted within a classical SK scheme, although the Si(100) growth exhibits significant relaxation and ripening with increasing coverage. Other novel aspects of the growth include the increased thickness of the wetting layer and the kinetic control of Si/Ge intermixing via the PLD repetition rate.

A general lithography-free method of microscale/nanoscale fabrication and patterning on Si and Ge surfaces

PubMed Central

2012-01-01

Here, we introduce and give an overview of a general lithography-free method to fabricate silicide and germanide micro-/nanostructures on Si and Ge surfaces through metal-vapor-initiated endoepitaxial growth. Excellent controls on shape and orientation are achieved by adjusting the substrate orientation and growth parameters. Furthermore, micro-/nanoscale pits with controlled morphologies can also be successfully fabricated on Si and Ge surfaces by taking advantage of the sublimation of silicides/germanides. The aim of this brief report is to illustrate the concept of lithography-free synthesis and patterning on surfaces of elemental semiconductors, and the differences and the challenges associated with the Si and the Ge surfaces will be discussed. Our results suggest that this low-cost bottom-up approach is promising for applications in functional nanodevices. PMID:22315969

Anisotropy of Seebeck coefficient in Si/Ge composite quantum dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsin, Cheng-Lun, E-mail: clhsin@ee.ncu.edu.tw; Tsai, Yue-Yun; Lee, Sheng-Wei

2016-08-22

In this report, Si{sub 5}Ge{sub 5} alloy and Si/Ge composite quantum dots (CQDs) layers were grown on Si substrates. Seebeck coefficient (S) of Si and Ge wafers, as well as these two samples, were patterned and measured from 60 to 180 °C in [110] and [010] directions. For Si, Ge, and Si{sub 5}Ge{sub 5}, the S of each is a constant in this temperature range. However, the S of the CQDs at 60–80 °C is anomalous and much higher than the others. The behavior of the voltage difference is linear to the temperature difference even as large as 50 °C, except for CQDsmore » at 60–80 °C. This result indicates that a narrow distribution of carriers energy with a sharp change in density of state near Fermi-level and selective carrier scattering in the miniband at Si/Ge interface make the discrepancy of charge transport enhanced. The CQDs can be a good candidate for temperature sensing and thermoelectric applications due to their high S and low thermal conductivity near room temperature.« less

Formation of uniform high-density and small-size Ge/Si quantum dots by scanning pulsed laser annealing of pre-deposited Ge/Si film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qayyum, Hamza; Chen, Szu-yuan, E-mail: sychen@ltl.iams.sinica.edu.tw; Department of Physics, National Central University, Zhongli, Taoyuan 320, Taiwan

2016-05-15

The capability to fabricate Ge/Si quantum dots with small dot size and high dot density uniformly over a large area is crucial for many applications. In this work, we demonstrate that this can be achieved by scanning a pre-deposited Ge thin layer on Si substrate with a line-focused pulsed laser beam to induce formation of quantum dots. With suitable setting, Ge/Si quantum dots with a mean height of 2.9 nm, a mean diameter of 25 nm, and a dot density of 6×10{sup 10} cm{sup −2} could be formed over an area larger than 4 mm{sup 2}. The average size ofmore » the laser-induced quantum dots is smaller while their density is higher than that of quantum dots grown by using Stranski-Krastanov growth mode. Based on the dependence of the characteristics of quantum dots on the laser parameters, a model consisting of laser-induced strain, surface diffusion, and Ostwald ripening is proposed for the mechanism underlying the formation of the Ge/Si quantum dots. The technique demonstrated could be applicable to other materials besides Ge/Si.« less

Atomic-order thermal nitridation of group IV semiconductors for ultra-large-scale integration

NASA Astrophysics Data System (ADS)

Murota, Junichi; Le Thanh, Vinh

2015-03-01

One of the main requirements for ultra-large-scale integration (ULSI) is atomic-order control of process technology. Our concept of atomically controlled processing for group IV semiconductors is based on atomic-order surface reaction control in Si-based CVD epitaxial growth. On the atomic-order surface nitridation of a few nm-thick Ge/about 4 nm-thick Si0.5Ge0.5/Si(100) by NH3, it is found that N atoms diffuse through nm-order thick Ge layer into Si0.5Ge0.5/Si(100) substrate and form Si nitride, even at 500 °C. By subsequent H2 heat treatment, although N atomic amount in Ge layer is reduced drastically, the reduction of the Si nitride is slight. It is suggested that N diffusion in Ge layer is suppressed by the formation of Si nitride and that Ge/atomic-order N layer/Si1-xGex/Si (100) heterostructure is formed. These results demonstrate the capability of CVD technology for atomically controlled nitridation of group IV semiconductors for ultra-large-scale integration. Invited talk at the 7th International Workshop on Advanced Materials Science and Nanotechnology IWAMSN2014, 2-6 November, 2014, Ha Long, Vietnam.

Growth and evolution of nickel germanide nanostructures on Ge(001).

PubMed

Grzela, T; Capellini, G; Koczorowski, W; Schubert, M A; Czajka, R; Curson, N J; Heidmann, I; Schmidt, Th; Falta, J; Schroeder, T

2015-09-25

Nickel germanide is deemed an excellent material system for low resistance contact formation for future Ge device modules integrated into mainstream, Si-based integrated circuit technologies. In this study, we present a multi-technique experimental study on the formation processes of nickel germanides on Ge(001). We demonstrate that room temperature deposition of ∼1 nm of Ni on Ge(001) is realized in the Volmer-Weber growth mode. Subsequent thermal annealing results first in the formation of a continuous NixGey wetting layer featuring well-defined terrace morphology. Upon increasing the annealing temperature to 300 °C, we observed the onset of a de-wetting process, characterized by the appearance of voids on the NixGey terraces. Annealing above 300 °C enhances this de-wetting process and the surface evolves gradually towards the formation of well-ordered, rectangular NixGey 3D nanostructures. Annealing up to 500 °C induces an Ostwald ripening phenomenon, with smaller nanoislands disappearing and larger ones increasing their size. Subsequent annealing to higher temperatures drives the Ni-germanide diffusion into the bulk and the consequent formation of highly ordered, {111} faceted Ni-Ge nanocrystals featuring an epitaxial relationship with the substrate Ni-Ge (101); (010) || Ge(001); (110).

Si0.7Ge0.3 Nanorings Mediated By Ag Nanodots: Structural Evolution and Enhanced Photoluminescence Properties

NASA Astrophysics Data System (ADS)

Ho, Chih; -Hau He, Cheng-Ying Chen, Jr.

2009-03-01

Currently nanorings (NRs) are attractive because there is a great deal of interest in nanostructures from theoretical, experimental, and device perspectives. The feasible NR fabrication is demanded in the field of electronic and optoelectronic devices at the nanoscale. In the present study, the growth of high-density Si0.7Ge0.3 NRs has been achieved on ultrathin Ag films on Si0.7Ge0.3 substrate. In situ ultrahigh-vacuum transmission electron microscopy revealed that the formation of nanorings involves a mechanism mediated by Ag NDs and evaporation of Ag-Si-Ge eutectic liquid at high temperature. Si0.7Ge0.3 NRs exhibit the enhanced PL intensity over Si0.7Ge0.3 thin film due to quantum size effects. The luminescence efficiency as a function of the size of Si0.7Ge0.3 NRs has been investigated. Power-dependent PL demonstrates that the NR mediated by Ag NDs is type-I band alignment. The process promising the availability of type-I Si1-xGex NRs can serve as a useful platform for the fundamental understanding and future practical applications of NRs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yiyin; Dou, Wei; Pham, Thach

Temperature-dependent characteristics of GeSn light-emitting diodes with Sn composition up to 9.2% have been systematically studied. Such diodes were based on Ge/GeSn/Ge double heterostructures (DHS) that were grown directly on a Si substrate via a chemical vapor deposition system. Both photoluminescence and electroluminescence spectra have been characterized at temperatures from 300 to 77 K. Based on our theoretical calculation, all GeSn alloys in this study are indirect bandgap materials. However, due to the small energy separation between direct and indirect bandgap, and the fact that radiative recombination rate greater than non-radiative, the emissions are mainly from the direct Γ-valley to valencemore » band transitions. The electroluminescence emissions under current injection levels from 102 to 357 A/cm{sup 2} were investigated at 300 K. The monotonic increase of the integrated electroluminescence intensity was observed for each sample. Moreover, the electronic band structures of the DHS were discussed. Despite the indirect GeSn bandgap owing to the compressive strain, type-I band alignment was achieved with the barrier heights ranging from 11 to 47 meV.« less

Extending the evaluation of Genia Event task toward knowledge base construction and comparison to Gene Regulation Ontology task

PubMed Central

2015-01-01

Background The third edition of the BioNLP Shared Task was held with the grand theme "knowledge base construction (KB)". The Genia Event (GE) task was re-designed and implemented in light of this theme. For its final report, the participating systems were evaluated from a perspective of annotation. To further explore the grand theme, we extended the evaluation from a perspective of KB construction. Also, the Gene Regulation Ontology (GRO) task was newly introduced in the third edition. The final evaluation of the participating systems resulted in relatively low performance. The reason was attributed to the large size and complex semantic representation of the ontology. To investigate potential benefits of resource exchange between the presumably similar tasks, we measured the overlap between the datasets of the two tasks, and tested whether the dataset for one task can be used to enhance performance on the other. Results We report an extended evaluation on all the participating systems in the GE task, incoporating a KB perspective. For the evaluation, the final submission of each participant was converted to RDF statements, and evaluated using 8 queries that were formulated in SPARQL. The results suggest that the evaluation may be concluded differently between the two different perspectives, annotation vs. KB. We also provide a comparison of the GE and GRO tasks by converting their datasets into each other's format. More than 90% of the GE data could be converted into the GRO task format, while only half of the GRO data could be mapped to the GE task format. The imbalance in conversion indicates that the GRO is a comprehensive extension of the GE task ontology. We further used the converted GRO data as additional training data for the GE task, which helped improve GE task participant system performance. However, the converted GE data did not help GRO task participants, due to overfitting and the ontology gap. PMID:26202680

Near Edge X-Ray Absorption and X-Ray Photoelectron Diffraction Studies of the Structural Environment of Ge-Si Systems

NASA Astrophysics Data System (ADS)

Castrucci, P.; Gunnella, R.; Pinto, N.; Bernardini, R.; de Crescenzi, M.; Sacchi, M.

Near edge X-ray absorption spectroscopy (XAS), X-ray photoelectron diffraction (XPD) and Auger electron diffraction (AED) are powerful techniques for the qualitative study of the structural and electronic properties of several systems. The recent development of a multiple scattering approach to simulating experimental spectra opened a friendly way to the study of structural environments of solids and surfaces. This article reviews recent X-ray absorption experiments using synchrotron radiation which were performed at Ge L edges and core level electron diffraction measurements obtained using a traditional X-ray source from Ge core levels for ultrathin Ge films deposited on silicon substrates. Thermodynamics and surface reconstruction have been found to play a crucial role in the first stages of Ge growth on Si(001) and Si(111) surfaces. Both techniques show the occurrence of intermixing processes even for room-temperature-grown Ge/Si(001) samples and give a straightforward measurement of the overlayer tetragonal distortion. The effects of Sb as a surfactant on the Ge/Si(001) interface have also been investigated. In this case, evidence of layer-by-layer growth of the fully strained Ge overlayer with a reduced intermixing is obtained when one monolayer of Sb is predeposited on the surface.

Dislocation-free Ge Nano-crystals via Pattern Independent Selective Ge Heteroepitaxy on Si Nano-Tip Wafers.

PubMed

Niu, Gang; Capellini, Giovanni; Schubert, Markus Andreas; Niermann, Tore; Zaumseil, Peter; Katzer, Jens; Krause, Hans-Michael; Skibitzki, Oliver; Lehmann, Michael; Xie, Ya-Hong; von Känel, Hans; Schroeder, Thomas

2016-03-04

The integration of dislocation-free Ge nano-islands was realized via selective molecular beam epitaxy on Si nano-tip patterned substrates. The Si-tip wafers feature a rectangular array of nanometer sized Si tips with (001) facet exposed among a SiO2 matrix. These wafers were fabricated by complementary metal-oxide-semiconductor (CMOS) compatible nanotechnology. Calculations based on nucleation theory predict that the selective growth occurs close to thermodynamic equilibrium, where condensation of Ge adatoms on SiO2 is disfavored due to the extremely short re-evaporation time and diffusion length. The growth selectivity is ensured by the desorption-limited growth regime leading to the observed pattern independence, i.e. the absence of loading effect commonly encountered in chemical vapor deposition. The growth condition of high temperature and low deposition rate is responsible for the observed high crystalline quality of the Ge islands which is also associated with negligible Si-Ge intermixing owing to geometric hindrance by the Si nano-tip approach. Single island as well as area-averaged characterization methods demonstrate that Ge islands are dislocation-free and heteroepitaxial strain is fully relaxed. Such well-ordered high quality Ge islands present a step towards the achievement of materials suitable for optical applications.

Dislocation-free Ge Nano-crystals via Pattern Independent Selective Ge Heteroepitaxy on Si Nano-Tip Wafers

PubMed Central

Niu, Gang; Capellini, Giovanni; Schubert, Markus Andreas; Niermann, Tore; Zaumseil, Peter; Katzer, Jens; Krause, Hans-Michael; Skibitzki, Oliver; Lehmann, Michael; Xie, Ya-Hong; von Känel, Hans; Schroeder, Thomas

2016-01-01

The integration of dislocation-free Ge nano-islands was realized via selective molecular beam epitaxy on Si nano-tip patterned substrates. The Si-tip wafers feature a rectangular array of nanometer sized Si tips with (001) facet exposed among a SiO2 matrix. These wafers were fabricated by complementary metal-oxide-semiconductor (CMOS) compatible nanotechnology. Calculations based on nucleation theory predict that the selective growth occurs close to thermodynamic equilibrium, where condensation of Ge adatoms on SiO2 is disfavored due to the extremely short re-evaporation time and diffusion length. The growth selectivity is ensured by the desorption-limited growth regime leading to the observed pattern independence, i.e. the absence of loading effect commonly encountered in chemical vapor deposition. The growth condition of high temperature and low deposition rate is responsible for the observed high crystalline quality of the Ge islands which is also associated with negligible Si-Ge intermixing owing to geometric hindrance by the Si nano-tip approach. Single island as well as area-averaged characterization methods demonstrate that Ge islands are dislocation-free and heteroepitaxial strain is fully relaxed. Such well-ordered high quality Ge islands present a step towards the achievement of materials suitable for optical applications. PMID:26940260

InN: A material with photovoltaic promise and challenges

NASA Astrophysics Data System (ADS)

Trybus, Elaissa; Namkoong, Gon; Henderson, Walter; Burnham, Shawn; Doolittle, W. Alan; Cheung, Maurice; Cartwright, Alexander

2006-03-01

The potential of InN as a photovoltaic material is described. For solar applications, several key developments such as p-type doping and solid-state rectifying junctions have yet to be demonstrated. However, the ability of InGaN materials to optimally span the solar spectrum offers a tantalizing solution for high-efficiency photovoltaics albeit in an inherently lattice mismatched material system. For this reason, the characteristics of InN grown on (1 1 1)-oriented germanium and (0 0 0 1)-plane sapphire substrates via molecular beam epitaxy for the application of InN solar cells is described. To provide an efficient sub-cell interconnect for tandem solar cells, epitaxial Al was deposited on a germanium substrate with InN grown on this epitaxial aluminum layer. Consistent with previous results, the electrical characteristics of n-InN/p-Ge, n-InN/n-Ge, and n-InN/Al/Ge were measured and showed no rectifying behavior. As evidenced by X-ray diffraction, minute amounts of unintentional oxygen incorporation during InN growth forms a secondary phase, tentatively assigned to an indium oxynitride, InON x, phase. Photoluminescence measurements of the InN/InON x show spectral peaks at ˜0.7 and ˜3.8 eV consistent with the bulk excitonic bandgap of the two materials. Photoluminescence was also found at ˜1.7 eV and shown to be related to emission from the sapphire substrates.

Crystallization kinetics of GeTe phase-change thin films grown by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Sun, Xinxing; Thelander, Erik; Gerlach, Jürgen W.; Decker, Ulrich; Rauschenbach, Bernd

2015-07-01

Pulsed laser deposition was employed to the growth of GeTe thin films on Silicon substrates. X-ray diffraction measurements reveal that the critical crystallization temperature lies between 220 and 240 °C. Differential scanning calorimetry was used to investigate the crystallization kinetics of the as-deposited films, determining the activation energy to be 3.14 eV. Optical reflectivity and in situ resistance measurements exhibited a high reflectivity contrast of ~21% and 3-4 orders of magnitude drop in resistivity of the films upon crystallization. The results show that pulsed laser deposited GeTe films can be a promising candidate for phase-change applications.

Controlled drive-in and precipitation of hydrogen during plasma hydrogenation of silicon using a thin compressively strained SiGe layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okba, F.; Departement Optique et Mecanique de Precision, Faculte des Sciences de l'Ingenieur, Universite Ferhat Abbas, Setif 19000; Cherkashin, N.

2010-07-19

We have quantitatively studied by transmission electron microscopy the growth kinetics of platelets formed during the continuous hydrogenation of a Si substrate/SiGe/Si heterostructure. We have evidenced and explained the massive transfer of hydrogen from a population of platelets initially generated in the upper Si layer by plasma hydrogenation towards a population of larger platelets located in the SiGe layer. We demonstrate that this type of process can be used not only to precisely localize the micro-cracks, then the fracture line at a given depth but also to 'clean' the top layer from pre-existing defects.

Novel Quantum Dot Gate FETs and Nonvolatile Memories Using Lattice-Matched II-VI Gate Insulators

NASA Astrophysics Data System (ADS)

Jain, F. C.; Suarez, E.; Gogna, M.; Alamoody, F.; Butkiewicus, D.; Hohner, R.; Liaskas, T.; Karmakar, S.; Chan, P.-Y.; Miller, B.; Chandy, J.; Heller, E.

2009-08-01

This paper presents the successful use of ZnS/ZnMgS and other II-VI layers (lattice-matched or pseudomorphic) as high- k gate dielectrics in the fabrication of quantum dot (QD) gate Si field-effect transistors (FETs) and nonvolatile memory structures. Quantum dot gate FETs and nonvolatile memories have been fabricated in two basic configurations: (1) monodispersed cladded Ge nanocrystals (e.g., GeO x -cladded-Ge quantum dots) site-specifically self-assembled over the lattice-matched ZnMgS gate insulator in the channel region, and (2) ZnTe-ZnMgTe quantum dots formed by self-organization, using metalorganic chemical vapor-phase deposition (MOCVD), on ZnS-ZnMgS gate insulator layers grown epitaxially on Si substrates. Self-assembled GeO x -cladded Ge QD gate FETs, exhibiting three-state behavior, are also described. Preliminary results on InGaAs-on-InP FETs, using ZnMgSeTe/ZnSe gate insulator layers, are presented.

Wet oxidation of GeSi strained layers by rapid thermal processing

NASA Astrophysics Data System (ADS)

Nayak, D. K.; Kamjoo, K.; Park, J. S.; Woo, J. C. S.; Wang, K. L.

1990-07-01

A cold-wall rapid thermal processor is used for the wet oxidation of the commensurately grown GexSi1-x layers on Si substrates. The rate of oxidation of the GexSi1-x layer is found to be significantly higher than that of pure Si, and the oxidation rate increases with the increase in the Ge content in GexSi1-x layer. The oxidation rate of GexSi1-x appears to decrease with increasing oxidation time for the time-temperature cycles considered here. Employing high-frequency and quasi-static capacitance-voltage measurements, it is found that a fixed negative oxide charge density in the range of 1011- 1012/cm2 and the interface trap level density (in the mid-gap region) of about 1012/cm2 eV are present. Further, the density of this fixed interface charge at the SiO2/GeSi interface is found to increase with the Ge concentration in the commensurately grown GeSi layers.

Carrier Density Modulation in Ge Heterostructure by Ferroelectric Switching

DOE PAGES

Ponath, Patrick; Fredrickson, Kurt; Posadas, Agham B.; ...

2015-01-14

The development of nonvolatile logic through direct coupling of spontaneous ferroelectric polarization with semiconductor charge carriers is nontrivial, with many issues, including epitaxial ferroelectric growth, demonstration of ferroelectric switching, and measurable semiconductor modulation. Here we report a true ferroelectric field effect carrier density modulation in an underlying Ge(001) substrate by switching of the ferroelectric polarization in the epitaxial c-axis-oriented BaTiO3 (BTO) grown by molecular beam epitaxy (MBE) on Ge. Using density functional theory, we demonstrate that switching of BTO polarization results in a large electric potential change in Ge. Aberration-corrected electron microscopy confirms the interface sharpness, and BTO tetragonality. Electron-energy-lossmore » spectroscopy (EELS) indicates the absence of any low permittivity interlayer at the interface with Ge. Using piezoelectric force microscopy (PFM), we confirm the presence of fully switchable, stable ferroelectric polarization in BTO that appears to be single domain. Using microwave impedance microscopy (MIM), we clearly demonstrate a ferroelectric field effect.« less

Impact of thickness on the structural properties of high tin content GeSn layers

NASA Astrophysics Data System (ADS)

Aubin, J.; Hartmann, J. M.; Gassenq, A.; Milord, L.; Pauc, N.; Reboud, V.; Calvo, V.

2017-09-01

We have grown various thicknesses of GeSn layers in a 200 mm industrial Reduced Pressure - Chemical Vapor Deposition cluster tool using digermane (Ge2H6) and tin tetrachloride (SnCl4). The growth pressure (100 Torr) and the F(Ge2H6)/F(SnCl4) mass-flow ratio were kept constant, and incorporation of tin in the range of 10-15% was achieved with a reduction in temperature: 325 °C for 10% to 301 °C for 15% of Sn. The layers were grown on 2.5 μm thick Ge Strain Relaxed Buffers, themselves on Si(0 0 1) substrates. We used X-ray Diffraction, Atomic Force Microscopy, Raman spectroscopy and Scanning Electron Microscopy to measure the Sn concentration, the strain state, the surface roughness and thickness as a function of growth duration. A dramatic degradation of the film was seen when the Sn concentration and layer thickness were too high resulting in rough/milky surfaces and significant Sn segregation.

Consecutive magnetic phase diagram of UCoGe-URhGe-UIrGe system

NASA Astrophysics Data System (ADS)

Pospíšil, Jiří; Haga, Yoshinori; Miyake, Atsushi; Kambe, Shinsaku; Tateiwa, Naoyuki; Tokunaga, Yo; Honda, Fuminori; Nakamura, Ai; Homma, Yoshiya; Tokunaga, Masashi; Aoki, Dai; Yamamoto, Etsuji

2018-05-01

We prepared single crystals in UCo1-xRhxGe and UIr1-xRhxGe systems to establish a complex dU-U-T (dU-U is the shortest interatomic uranium distance and T is temperature) magnetic phase diagram. This recognized a characteristic maximum in magnetic susceptibility at temperature Tmax along the b axis as an important parameter. Three magnetically ordered regions can be distinguished within this scope; first a ferromagnetic region with Curie temperature

Fluorescence X-ray absorption spectroscopy using a Ge pixel array detector: application to high-temperature superconducting thin-film single crystals.

PubMed

Oyanagi, H; Tsukada, A; Naito, M; Saini, N L; Lampert, M O; Gutknecht, D; Dressler, P; Ogawa, S; Kasai, K; Mohamed, S; Fukano, A

2006-07-01

A Ge pixel array detector with 100 segments was applied to fluorescence X-ray absorption spectroscopy, probing the local structure of high-temperature superconducting thin-film single crystals (100 nm in thickness). Independent monitoring of pixel signals allows real-time inspection of artifacts owing to substrate diffractions. By optimizing the grazing-incidence angle theta and adjusting the azimuthal angle phi, smooth extended X-ray absorption fine structure (EXAFS) oscillations were obtained for strained (La,Sr)2CuO4 thin-film single crystals grown by molecular beam epitaxy. The results of EXAFS data analysis show that the local structure (CuO6 octahedron) in (La,Sr)2CuO4 thin films grown on LaSrAlO4 and SrTiO3 substrates is uniaxially distorted changing the tetragonality by approximately 5 x 10(-3) in accordance with the crystallographic lattice mismatch. It is demonstrated that the local structure of thin-film single crystals can be probed with high accuracy at low temperature without interference from substrates.

Synergistic effects of semiconductor substrate and noble metal nano-particles on SERS effect both theoretical and experimental aspects

NASA Astrophysics Data System (ADS)

Yang, Chen; Liang, Pei; Tang, Lisha; Zhou, Yongfeng; Cao, Yanting; Wu, Yanxiong; Zhang, De; Dong, Qianmin; Huang, Jie; He, Peng

2018-04-01

As a means of chemical identification and analysis, Surface enhanced Raman spectroscopy (SERS), with the advantages of high sensitivity and selectivity, non-destructive, high repeatability and in situ detection etc., has important significance in the field of composition detection, environmental science, biological medicine etc. Physical model of coupling effect between different semiconductor substrates and noble metal particles were investigated by using 3D-FDTD method. Mechanism and the effects of excitation wavelength, particle spacing and semiconductor substrate types on the SERS effect were discussed. The results showed that the optimal excitation wavelengths of three noble metals of Ag, Au, Cu, were located at 510, 600 and 630 nm, respectively; SERS effect of Ag, Au, Cu increases with the decreasing of the inter distance of particles, while the distance of the NPs reaches the critical value of 3 nm, the strength of SERS effect will be greatly enhanced. For the four different types of substrate of Ge, Si, SiO2 (glass) and Al2O3, the SERS effect of Ag on SiO2 > Ge > Al2O3 > Si. For Au and Cu nanoparticles, the SERS effect of them on oxide substrate is stronger than that on non-oxide substrate. In order to verify FDTD simulations, taking silver nanoparticles as an example, and silver nanoparticles prepared by chemical method were spinning coating on the four different substrates with R6G as probe molecules. The results show that the experimental results are consistent with FDTD theoretical simulations, and the SERS enhancement effect of Ag-SiO2 substrate is best. The results of this study have important theoretical significance to explain the variations of SERS enhancement on different noble metals, which is also an important guide for the preparation of SERS substrates, especially for the microfluidics. The better Raman effect can be realized by choosing proper substrate type, particle spacing and excitation wavelength, result in expanding the depth and width of SERS application.

DFT study of cyanide oxidation on surface of Ge-embedded carbon nanotube

NASA Astrophysics Data System (ADS)

Gao, Wei; Milad Abrishamifar, Seyyed; Ebrahimzadeh Rajaei, Gholamreza; Razavi, Razieh; Najafi, Meysam

2018-03-01

In recent years, the discovery of suitable catalyst to oxidation of the cyanide (CN) has high importance in the industry. In present study, in the first step, the carbon nanotube (CNT) with the Ge atom embedded and the surface of Ge-CNT via the O2 molecule activated. In second step, the oxidation of CN on surface of the Ge-CNT via the Langmuir Hinshelwood (LH) and the Eley Rideal (ER) mechanisms was investigated. Results show that O2-Ge-CNT oxidized the CN molecule via the Ge-CNT-O-O∗ + CN → Ge-CNT-O-O∗-CN → Ge-CNT-O∗ + OCN and the Ge-CNT-O∗ + CN → Ge-CNT + OCN reactions. Results show that oxidation of CN on surface of Ge-CNT via the LH mechanism has lower energy barrier than ER mechanism. Finally, calculated parameters reveal that Ge-CNT is acceptable catalyst with high performance for CN oxidation, form theoretical point of view.

Thermoelectric Figure-of-Merit of Nanostructured Silicon with a Low Concentration of Germanium

NASA Astrophysics Data System (ADS)

Zhu, Gaohua; Lee, Hohyun; Lan, Yucheng; Wang, Xiaowei; Joshi, Giri; Wang, Dezhi; Yang, Jian; Dresselhaus, Mildred; Chen, Gang; Ren, Zhifeng

2009-03-01

The thermoelectric properties of nanostructured silicon (Si) with a low concentration of germanium (Ge) are investigated. A low concentration of Ge leads to a significant cost reduction of the final product since Ge is at least 100 times more expensive than Si. By using only 5 atomic % Ge (Si95Ge5), we have achieved a thermoelectric figure-of-merit (ZT) of 0.95, similar to the ZT in the large grained Si80Ge20 alloy that is three times more expensive, and is almost four times that of the large grained bulk Si. The enhancement in the thermoelectric ZT for the nanostructured Si95Ge5 is mostly due to the reduced thermal conductivity caused by phonon scattering at the increased grain boundaries and the Ge alloying effect.

Search for the dark photon and the dark Higgs boson at belle.

PubMed

Jaegle, I; Adachi, I; Aihara, H; Al Said, S; Asner, D M; Aushev, T; Ayad, R; Bakich, A M; Bansal, V; Barrett, M; Bhuyan, B; Bozek, A; Bračko, M; Browder, T E; Červenkov, D; Chang, M-C; Cheon, B G; Chilikin, K; Cho, K; Chobanova, V; Choi, S-K; Choi, Y; Cinabro, D; Dalseno, J; Doležal, Z; Drásal, Z; Drutskoy, A; Dutta, D; Eidelman, S; Epifanov, D; Farhat, H; Fast, J E; Ferber, T; Frost, O; Gaur, V; Gabyshev, N; Ganguly, S; Garmash, A; Getzkow, D; Gillard, R; Goh, Y M; Golob, B; Grzymkowska, O; Hayasaka, K; Hayashii, H; He, X H; Hedges, M; Hou, W-S; Iijima, T; Inami, K; Ishikawa, A; Iwasaki, Y; Julius, T; Kang, K H; Kato, E; Kawasaki, T; Kim, D Y; Kim, J B; Kim, J H; Kim, S H; Kinoshita, K; Ko, B R; Kodyš, P; Korpar, S; Križan, P; Krokovny, P; Kuzmin, A; Kwon, Y-J; Lange, J S; Lee, I S; Lewis, P; Li Gioi, L; Libby, J; Liventsev, D; Matvienko, D; Miyata, H; Mizuk, R; Mohanty, G B; Moll, A; Mussa, R; Nakano, E; Nakao, M; Nisar, N K; Nishida, S; Ogawa, S; Pakhlov, P; Pakhlova, G; Park, H; Pedlar, T K; Pesántez, L; Petrič, M; Piilonen, L E; Ritter, M; Rostomyan, A; Sakai, Y; Sandilya, S; Santelj, L; Sanuki, T; Sato, Y; Savinov, V; Schneider, O; Schnell, G; Schwanda, C; Semmler, D; Senyo, K; Seon, O; Seong, I; Sevior, M E; Shebalin, V; Shibata, T-A; Shiu, J-G; Shwartz, B; Simon, F; Sinha, R; Sohn, Y-S; Starič, M; Sumihama, M; Sumisawa, K; Tamponi, U; Tatishvili, G; Teramoto, Y; Thorne, F; Uchida, M; Uehara, S; Unno, Y; Uno, S; Vahsen, S E; Van Hulse, C; Vanhoefer, P; Varner, G; Vinokurova, A; Wagner, M N; Wang, C H; Wang, M-Z; Wang, P; Wang, X L; Watanabe, M; Watanabe, Y; Williams, K M; Won, E; Yamaoka, J; Yashchenko, S; Yook, Y; Yusa, Y; Zhilich, V; Zhulanov, V; Zupanc, A

2015-05-29

The dark photon A^{'} and the dark Higgs boson h^{'} are hypothetical constituents featured in a number of recently proposed dark sector models. Assuming prompt decays of both dark particles, we search for their production in the so-called Higgstrahlung channel e^{+}e^{-}→A^{'}h^{'}, with h^{'}→A^{'}A^{'}. We investigate ten exclusive final states with A^{'}→e^{+}e^{-}, μ^{+}μ^{-}, or π^{+}π^{-} in the mass ranges 0.1  GeV/c^{2} 

Precise Nanoelectronics with Adatom Chains

NASA Technical Reports Server (NTRS)

Yamada, Toshishige

1999-01-01

Adatom chains on an atomically regulated substrate will be building components in future precise nanoelectronics. Adatoms need to be secured with chemical bonding, but then electronic isolation between the adatom and substrate systems is not guaranteed. A one-dimensional model shows that good isolation with existence of surface states is expected on an s-p crossing substrate such as Si, Ge, or GaAs, reflecting the bulk nature of the substrate. Isolation is better if adatoms are electronically similar to the substrate atoms, and can be manipulated by hydrogenation. Chain structures with group IV adatoms with two chemical bonds, or group III adatoms with one chemical bond, are semiconducting, reflecting the surface nature of the substrate. These structures are unintentionally doped due to the charge transfer across the chemical bonds. Physical properties of adatom chains have to be determined for the unified adatom-substrate system.

Material parameters from frequency dispersion simulation of floating gate memory with Ge nanocrystals in HfO2

NASA Astrophysics Data System (ADS)

Palade, C.; Lepadatu, A. M.; Slav, A.; Lazanu, S.; Teodorescu, V. S.; Stoica, T.; Ciurea, M. L.

2018-01-01

Trilayer memory capacitors with Ge nanocrystals (NCs) floating gate in HfO2 were obtained by magnetron sputtering deposition on p-type Si substrate followed by rapid thermal annealing at relatively low temperature of 600 °C. The frequency dispersion of capacitance and resistance was measured in accumulation regime of Al/HfO2 gate oxide/Ge NCs in HfO2 floating gate/HfO2 tunnel oxide/SiOx/p-Si/Al memory capacitors. For simulation of the frequency dispersion a complex circuit model was used considering an equivalent parallel RC circuit for each layer of the trilayer structure. A series resistance due to metallic contacts and Si substrate was necessary to be included in the model. A very good fit to the experimental data was obtained and the parameters of each layer in the memory capacitor, i.e. capacitances and resistances were determined and in turn the intrinsic material parameters, i.e. dielectric constants and resistivities of layers were evaluated. The results are very important for the study and optimization of the hysteresis behaviour of floating gate memories based on NCs embedded in oxide.

Development of Phase Change Materials for RF Switch Applications

NASA Astrophysics Data System (ADS)

King, Matthew Russell

For decades chalcogenide-based phase change materials (PCMs) have been reliably implemented in optical storage and digital memory platforms. Owing to the substantial differences in optical and electronic properties between crystalline and amorphous states, device architectures requiring a "1" and "0" or "ON" and "OFF" states are attainable with PCMs if a method for amorphizing and crystallizing the PCM is demonstrated. Taking advantage of more than just the binary nature of PCM electronic properties, recent reports have shown that the near-metallic resistivity of some PCMs allow one to manufacture high performance RF switches and related circuit technologies. One of the more promising RF switch technologies is the Inline Phase Change Switch (IPCS) which utilizes GeTe as the active material. Initial reports show that an electrically isolated, thermally coupled thin film heater can successfully convert GeTe between crystalline and amorphous states, and with proper design an RF figure of merit cutoff frequency (FCO) of 12.5 THz can be achieved. In order to realize such world class performance a significant development effort was undertaken to understand the relationship between fundamental GeTe properties, thin film deposition method and resultant device properties. Deposition pressure was found to be the most important deposition process parameter, as it was found to control Ge:Te ratio, oxygen content, Ar content, film density and surface roughness. Ultimately a first generation deposition process produced GeTe films with a crystalline resistivity of 3 ohm-mum. Upon implementing these films into IPCS devices, post-cycling morphological analysis was undertaken using STEM and related analyses. It was revealed that massive structural changes occur in the GeTe during switching, most notably the formation of an assembly of voids along the device centerline and large GeTe grains on either side of the so-called active region. Restructuring of this variety was tied to changes in ON-state resistance with increasing pulse number, where initially porous and granular GeTe was converted to large crystalline domains comprising the majority of the RF gap. A phenomenological model for this morphology was presented in which the OFF pulse melts a given width of GeTe and upon cooling the crystalline template outside the melt region acts as a template for an inward-propagating crystalline growth front. This model was further extended to explain observed morphology for ON pulses. The voids observed along the device centerline were connected to increasing OFF state resistance and a relatively stable ON state with increasing pulse number via a series resistance model. As a result of this analysis, OFF state resistance was suggested as an early indicator of device reliability. Finally, microstructural and electrical property observations were used as a basis for implementing improvements to the GeTe deposition process in the form of a heated substrate platform. It was shown that this provides a viable method for attaining stable as-deposited GeTe morphology and a substantially improved crystalline resistivity (2 ohm-mum). This body of work ultimately provides a blueprint which connects fundamental GeTe properties with deposition processes and device performance.

Silane and Germane Molecular Electronics.

PubMed

Su, Timothy A; Li, Haixing; Klausen, Rebekka S; Kim, Nathaniel T; Neupane, Madhav; Leighton, James L; Steigerwald, Michael L; Venkataraman, Latha; Nuckolls, Colin

2017-04-18

This Account provides an overview of our recent efforts to uncover the fundamental charge transport properties of Si-Si and Ge-Ge single bonds and introduce useful functions into group 14 molecular wires. We utilize the tools of chemical synthesis and a scanning tunneling microscopy-based break-junction technique to study the mechanism of charge transport in these molecular systems. We evaluated the fundamental ability of silicon, germanium, and carbon molecular wires to transport charge by comparing conductances within families of well-defined structures, the members of which differ only in the number of Si (or Ge or C) atoms in the wire. For each family, this procedure yielded a length-dependent conductance decay parameter, β. Comparison of the different β values demonstrates that Si-Si and Ge-Ge σ bonds are more conductive than the analogous C-C σ bonds. These molecular trends mirror what is seen in the bulk. The conductance decay of Si and Ge-based wires is similar in magnitude to those from π-based molecular wires such as paraphenylenes However, the chemistry of the linkers that attach the molecular wires to the electrodes has a large influence on the resulting β value. For example, Si- and Ge-based wires of many different lengths connected with a methyl-thiomethyl linker give β values of 0.36-0.39 Å -1 , whereas Si- and Ge-based wires connected with aryl-thiomethyl groups give drastically different β values for short and long wires. This observation inspired us to study molecular wires that are composed of both π- and σ-orbitals. The sequence and composition of group 14 atoms in the σ chain modulates the electronic coupling between the π end-groups and dictates the molecular conductance. The conductance behavior originates from the coupling between the subunits, which can be understood by considering periodic trends such as bond length, polarizability, and bond polarity. We found that the same periodic trends determine the electric field-induced breakdown properties of individual Si-Si, Ge-Ge, Si-O, Si-C, and C-C bonds. Building from these studies, we have prepared a system that has two different, alternative conductance pathways. In this wire, we can intentionally break a labile, strained silicon-silicon bond and thereby shunt the current through the secondary conduction pathway. This type of in situ bond-rupture provides a new tool to study single molecule reactions that are induced by electric fields. Moreover, these studies provide guidance for designing dielectric materials as well as molecular devices that require stability under high voltage bias. The fundamental studies on the structure/function relationships of the molecular wires have guided the design of new functional systems based on the Si- and Ge-based wires. For example, we exploited the principle of strain-induced Lewis acidity from reaction chemistry to design a single molecule switch that can be controllably switched between two conductive states by varying the distance between the tip and substrate electrodes. We found that the strain intrinsic to the disilaacenaphthene scaffold also creates two state conductance switching. Finally, we demonstrate the first example of a stereoelectronic conductance switch, and we demonstrate that the switching relies crucially on the electronic delocalization in Si-Si and Ge-Ge wire backbones. These studies illustrate the untapped potential in using Si- and Ge-based wires to design and control charge transport at the nanoscale and to allow quantum mechanics to be used as a tool to design ultraminiaturized switches.

Preparation and Characterization of Thin-Film Composite Membrane with Nanowire-Modified Support for Forward Osmosis Process

PubMed Central

Low, Ze-Xian; Liu, Qi; Shamsaei, Ezzatollah; Zhang, Xiwang; Wang, Huanting

2015-01-01

Internal concentration polarization (ICP) in forward osmosis (FO) process is a characteristic problem for asymmetric thin-film composite (TFC) FO membrane which leads to lower water flux. To mitigate the ICP effect, modification of the substrates’ properties has been one of the most effective methods. A new polyethersulfone-based ultrafiltration membrane with increased surface porosity and high water flux was recently produced by incorporating Zn2GeO4 nanowires. The composite membrane was used as a substrate for the fabrication of TFC FO membrane, by coating a thin layer of polyamide on top of the substrate. The substrate and the nanowires were characterized by a range of techniques such as SEM, XRD, and contact angle goniometry. The water permeability and molecular weight cut-offs (MWCO) of the substrate; and the FO performance of the TFC membrane were also determined. The Zn2GeO4-modified membrane showed ~45% increase in water permeability and NaCl salt rejection of 80% under RO mode. In FO mode, the ratio of water flux to reverse solute flux was also improved. However, lower FO flux was obtained which could be due to ICP. The result shows that Zn2GO4 nanowire may be used as a modifier to the substrate to improve the quality of the polyamide layer on the substrate to improve the flux and selectivity, but not as effective in reducing ICP. This work demonstrates that the incorporation of nanomaterials to the membrane substrate may be an alternative approach to improve the formation of polyamide skin layer to achieve better FO performance. PMID:25803239

Progress toward a 30 percent-efficient, monolithic, three-junction, two-terminal concentrator solar cell for space applications

NASA Technical Reports Server (NTRS)

Partain, L. D.; Chung, B.-C.; Virshup, G. F.; Schultz, J. C.; Macmillan, H. F.; Ristow, M. Ladle; Kuryla, M. S.; Bertness, K. A.

1991-01-01

Component efficiencies of 0.2/sq cm cells at approximately 100x AMO light concentration and 80 C temperatures are not at 15.3 percent for a 1.9 eV AlGaAs top cell, 9.9 percent for a 1.4 eV GaAs middle cell under a 1.9 eV AlGaAs filter, and 2.4 percent for a bottom 1.0 eV InGaAs cell under a GaAs substrate. The goal is to continue improvement in these performance levels and to sequentially grow these devices on a single substrate to give 30 percent efficient, monolithic, two-terminal, three-junction space concentrator cells. The broad objective is a 30 percent efficient monolithic two-terminal cell that can operate under 25 to 100x AMO light concentrations and at 75 to 100 C cell temperatures. Detailed modeling predicts that this requires three junctions. Two options are being pursued, and both use a 1.9 eV AlGaAs top junction and a 1.4 eV GaAs middle junction grown by a 1 atm OMVPE on a lattice matched substrate. Option 1 uses a low-doped GaAs substrate with a lattice mismatched 1.0 eV InGaAs cell formed on the back of the substrate. Option 2 uses a Ge substrate to which the AlGaAs and GaAs top junctions are lattice matched, with a bottom 0.7 eV Ge junction formed near the substrate interface with the GaAs growth. The projected efficiency contributions are near 16, 11, and 3 percent, respectively, from the top, middle, and bottom junctions.

Search for top squarks and dark matter particles in opposite-charge dilepton final states at √{s }=13 TeV

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Grossmann, J.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; Pree, E.; Rad, N.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Spanring, M.; Spitzbart, D.; Waltenberger, W.; Wittmann, J.; Wulz, C.-E.; Zarucki, M.; Chekhovsky, V.; Mossolov, V.; Suarez Gonzalez, J.; De Wolf, E. A.; Di Croce, D.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; De Bruyn, I.; De Clercq, J.; Deroover, K.; Flouris, G.; Lontkovskyi, D.; Lowette, S.; Marchesini, I.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Beghin, D.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Dorney, B.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Lenzi, T.; Luetic, J.; Maerschalk, T.; Marinov, A.; Seva, T.; Starling, E.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Roskas, C.; Salva, S.; Tytgat, M.; Verbeke, W.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caputo, C.; Caudron, A.; David, P.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Saggio, A.; Vidal Marono, M.; Wertz, S.; Zobec, J.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Coelho, E.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Melo De Almeida, M.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Sanchez Rosas, L. J.; Santoro, A.; Sznajder, A.; Thiel, M.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Misheva, M.; Rodozov, M.; Shopova, M.; Sultanov, G.; Dimitrov, A.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Gao, X.; Yuan, L.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Jiang, C. H.; Leggat, D.; Liao, H.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Yazgan, E.; Zhang, H.; Zhang, S.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Segura Delgado, M. A.; Courbon, B.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Starodumov, A.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; El-khateeb, E.; Elgammal, S.; Mohamed, A.; Dewanjee, R. K.; Kadastik, M.; Perrini, L.; Raidal, M.; Tiko, A.; Veelken, C.; Eerola, P.; Kirschenmann, H.; Pekkanen, J.; Voutilainen, M.; Havukainen, J.; Heikkilä, J. K.; Järvinen, T.; Karimäki, V.; Kinnunen, R.; Lampén, T.; Lassila-Perini, K.; Laurila, S.; Lehti, S.; Lindén, T.; Luukka, P.; Siikonen, H.; Tuominen, E.; Tuominiemi, J.; Tuuva, T.; Besancon, M.; Couderc, F.; Dejardin, M.; Denegri, D.; Faure, J. L.; Ferri, F.; Ganjour, S.; Ghosh, S.; Gras, P.; Hamel de Monchenault, G.; Jarry, P.; Kucher, I.; Leloup, C.; Locci, E.; Machet, M.; Malcles, J.; Negro, G.; Rander, J.; Rosowsky, A.; Sahin, M. Ö.; Titov, M.; Abdulsalam, A.; Amendola, C.; Antropov, I.; Baffioni, S.; Beaudette, F.; Busson, P.; Cadamuro, L.; Charlot, C.; Granier de Cassagnac, R.; Jo, M.; Lisniak, S.; Lobanov, A.; Martin Blanco, J.; Nguyen, M.; Ochando, C.; Ortona, G.; Paganini, P.; Pigard, P.; Salerno, R.; Sauvan, J. B.; Sirois, Y.; Stahl Leiton, A. G.; Strebler, T.; Yilmaz, Y.; Zabi, A.; Zghiche, A.; Agram, J.-L.; Andrea, J.; Bloch, D.; Brom, J.-M.; Buttignol, M.; Chabert, E. C.; Chanon, N.; Collard, C.; Conte, E.; Coubez, X.; Fontaine, J.-C.; Gelé, D.; Goerlach, U.; Jansová, M.; Le Bihan, A.-C.; Tonon, N.; Van Hove, P.; Gadrat, S.; Beauceron, S.; Bernet, C.; Boudoul, G.; Chierici, R.; Contardo, D.; Depasse, P.; El Mamouni, H.; Fay, J.; Finco, L.; Gascon, S.; Gouzevitch, M.; Grenier, G.; Ille, B.; Lagarde, F.; Laktineh, I. B.; Lethuillier, M.; Mirabito, L.; Pequegnot, A. L.; Perries, S.; Popov, A.; Sordini, V.; Vander Donckt, M.; Viret, S.; Khvedelidze, A.; Tsamalaidze, Z.; Autermann, C.; Feld, L.; Kiesel, M. K.; Klein, K.; Lipinski, M.; Preuten, M.; Schomakers, C.; Schulz, J.; Zhukov, V.; Albert, A.; Dietz-Laursonn, E.; Duchardt, D.; Endres, M.; Erdmann, M.; Erdweg, S.; Esch, T.; Fischer, R.; Güth, A.; Hamer, M.; Hebbeker, T.; Heidemann, C.; Hoepfner, K.; Knutzen, S.; Merschmeyer, M.; Meyer, A.; Millet, P.; Mukherjee, S.; Pook, T.; Radziej, M.; Reithler, H.; Rieger, M.; Scheuch, F.; Teyssier, D.; Thüer, S.; Flügge, G.; Kargoll, B.; Kress, T.; Künsken, A.; Müller, T.; Nehrkorn, A.; Nowack, A.; Pistone, C.; Pooth, O.; Stahl, A.; Aldaya Martin, M.; Arndt, T.; Asawatangtrakuldee, C.; Beernaert, K.; Behnke, O.; Behrens, U.; Bermúdez Martínez, A.; Bin Anuar, A. A.; Borras, K.; Botta, V.; Campbell, A.; Connor, P.; Contreras-Campana, C.; Costanza, F.; Diez Pardos, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Eren, E.; Gallo, E.; Garay Garcia, J.; Geiser, A.; Grados Luyando, J. M.; Grohsjean, A.; Gunnellini, P.; Guthoff, M.; Harb, A.; Hauk, J.; Hempel, M.; Jung, H.; Kasemann, M.; Keaveney, J.; Kleinwort, C.; Korol, I.; Krücker, D.; Lange, W.; Lelek, A.; Lenz, T.; Leonard, J.; Lipka, K.; Lohmann, W.; Mankel, R.; Melzer-Pellmann, I.-A.; Meyer, A. B.; Mittag, G.; Mnich, J.; Mussgiller, A.; Ntomari, E.; Pitzl, D.; Raspereza, A.; Savitskyi, M.; Saxena, P.; Shevchenko, R.; Spannagel, S.; Stefaniuk, N.; Van Onsem, G. P.; Walsh, R.; Wen, Y.; Wichmann, K.; Wissing, C.; Zenaiev, O.; Aggleton, R.; Bein, S.; Blobel, V.; Centis Vignali, M.; Dreyer, T.; Garutti, E.; Gonzalez, D.; Haller, J.; Hinzmann, A.; Hoffmann, M.; Karavdina, A.; Klanner, R.; Kogler, R.; Kovalchuk, N.; Kurz, S.; Lapsien, T.; Marconi, D.; Meyer, M.; Niedziela, M.; Nowatschin, D.; Pantaleo, F.; Peiffer, T.; Perieanu, A.; Scharf, C.; Schleper, P.; Schmidt, A.; Schumann, S.; Schwandt, J.; Sonneveld, J.; Stadie, H.; Steinbrück, G.; Stober, F. M.; Stöver, M.; Tholen, H.; Troendle, D.; Usai, E.; Vanhoefer, A.; Vormwald, B.; Akbiyik, M.; Barth, C.; Baselga, M.; Baur, S.; Butz, E.; Caspart, R.; Chwalek, T.; Colombo, F.; De Boer, W.; Dierlamm, A.; Faltermann, N.; Freund, B.; Friese, R.; Giffels, M.; Harrendorf, M. A.; Hartmann, F.; Heindl, S. M.; Husemann, U.; Kassel, F.; Kudella, S.; Mildner, H.; Mozer, M. U.; Müller, Th.; Plagge, M.; Quast, G.; Rabbertz, K.; Schröder, M.; Shvetsov, I.; Sieber, G.; Simonis, H. J.; Ulrich, R.; Wayand, S.; Weber, M.; Weiler, T.; Williamson, S.; Wöhrmann, C.; Wolf, R.; Anagnostou, G.; Daskalakis, G.; Geralis, T.; Kyriakis, A.; Loukas, D.; Topsis-Giotis, I.; Karathanasis, G.; Kesisoglou, S.; Panagiotou, A.; Saoulidou, N.; Kousouris, K.; Evangelou, I.; Foudas, C.; Kokkas, P.; Mallios, S.; Manthos, N.; Papadopoulos, I.; Paradas, E.; Strologas, J.; Triantis, F. A.; Csanad, M.; Filipovic, N.; Pasztor, G.; Surányi, O.; Veres, G. I.; Bencze, G.; Hajdu, C.; Horvath, D.; Hunyadi, Á.; Sikler, F.; Veszpremi, V.; Beni, N.; Czellar, S.; Karancsi, J.; Makovec, A.; Molnar, J.; Szillasi, Z.; Bartók, M.; Raics, P.; Trocsanyi, Z. L.; Ujvari, B.; Choudhury, S.; Komaragiri, J. R.; Bahinipati, S.; Bhowmik, S.; Mal, P.; Mandal, K.; Nayak, A.; Sahoo, D. K.; Sahoo, N.; Swain, S. K.; Bansal, S.; Beri, S. B.; Bhatnagar, V.; Chawla, R.; Dhingra, N.; Kalsi, A. K.; Kaur, A.; Kaur, M.; Kaur, S.; Kumar, R.; Kumari, P.; Mehta, A.; Singh, J. B.; Walia, G.; Kumar, Ashok; Shah, Aashaq; Bhardwaj, A.; Chauhan, S.; Choudhary, B. C.; Garg, R. B.; Keshri, S.; Kumar, A.; Malhotra, S.; Naimuddin, M.; Ranjan, K.; Sharma, R.; Bhardwaj, R.; Bhattacharya, R.; Bhattacharya, S.; Bhawandeep, U.; Dey, S.; Dutt, S.; Dutta, S.; Ghosh, S.; Majumdar, N.; Modak, A.; Mondal, K.; Mukhopadhyay, S.; Nandan, S.; Purohit, A.; Roy, A.; Roy Chowdhury, S.; Sarkar, S.; Sharan, M.; Thakur, S.; Behera, P. K.; Chudasama, R.; Dutta, D.; Jha, V.; Kumar, V.; Mohanty, A. K.; Netrakanti, P. K.; Pant, L. M.; Shukla, P.; Topkar, A.; Aziz, T.; Dugad, S.; Mahakud, B.; Mitra, S.; Mohanty, G. B.; Sur, N.; Sutar, B.; Banerjee, S.; Bhattacharya, S.; Chatterjee, S.; Das, P.; Guchait, M.; Jain, Sa.; Kumar, S.; Maity, M.; Majumder, G.; Mazumdar, K.; Sarkar, T.; Wickramage, N.; Chauhan, S.; Dube, S.; Hegde, V.; Kapoor, A.; Kothekar, K.; Pandey, S.; Rane, A.; Sharma, S.; Chenarani, S.; Eskandari Tadavani, E.; Etesami, S. M.; Khakzad, M.; Mohammadi Najafabadi, M.; Naseri, M.; Paktinat Mehdiabadi, S.; Rezaei Hosseinabadi, F.; Safarzadeh, B.; Zeinali, M.; Felcini, M.; Grunewald, M.; Abbrescia, M.; Calabria, C.; Colaleo, A.; Creanza, D.; Cristella, L.; De Filippis, N.; De Palma, M.; Errico, F.; Fiore, L.; Iaselli, G.; Lezki, S.; Maggi, G.; Maggi, M.; Miniello, G.; My, S.; Nuzzo, S.; Pompili, A.; Pugliese, G.; Radogna, R.; Ranieri, A.; Selvaggi, G.; Sharma, A.; Silvestris, L.; Venditti, R.; Verwilligen, P.; Abbiendi, G.; Battilana, C.; Bonacorsi, D.; Borgonovi, L.; Braibant-Giacomelli, S.; Campanini, R.; Capiluppi, P.; Castro, A.; Cavallo, F. R.; Chhibra, S. S.; Codispoti, G.; Cuffiani, M.; Dallavalle, G. M.; Fabbri, F.; Fanfani, A.; Fasanella, D.; Giacomelli, P.; Grandi, C.; Guiducci, L.; Marcellini, S.; Masetti, G.; Montanari, A.; Navarria, F. L.; Perrotta, A.; Rossi, A. M.; Rovelli, T.; Siroli, G. P.; Tosi, N.; Albergo, S.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Tricomi, A.; Tuve, C.; Barbagli, G.; Chatterjee, K.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Sguazzoni, G.; Strom, D.; Viliani, L.; Benussi, L.; Bianco, S.; Fabbri, F.; Piccolo, D.; Primavera, F.; Calvelli, V.; Ferro, F.; Robutti, E.; Tosi, S.; Benaglia, A.; Beschi, A.; Brianza, L.; Brivio, F.; Ciriolo, V.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Ghezzi, A.; Govoni, P.; Malberti, M.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Paganoni, M.; Pauwels, K.; Pedrini, D.; Pigazzini, S.; Ragazzi, S.; Tabarelli de Fatis, T.; Buontempo, S.; Cavallo, N.; Di Guida, S.; Fabozzi, F.; Fienga, F.; Iorio, A. O. M.; Khan, W. A.; Lista, L.; Meola, S.; Paolucci, P.; Sciacca, C.; Thyssen, F.; Azzi, P.; Bacchetta, N.; Benato, L.; Bisello, D.; Boletti, A.; Carlin, R.; Carvalho Antunes De Oliveira, A.; Checchia, P.; Dall'Osso, M.; De Castro Manzano, P.; Dorigo, T.; Dosselli, U.; Gasparini, F.; Gasparini, U.; Lacaprara, S.; Lujan, P.; Meneguzzo, A. T.; Pantano, D.; Pozzobon, N.; Ronchese, P.; Rossin, R.; Simonetto, F.; Torassa, E.; Zanetti, M.; Zotto, P.; Zumerle, G.; Braghieri, A.; Magnani, A.; Montagna, P.; Ratti, S. P.; Re, V.; Ressegotti, M.; Riccardi, C.; Salvini, P.; Vai, I.; Vitulo, P.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Ciangottini, D.; Fanò, L.; Lariccia, P.; Leonardi, R.; Manoni, E.; Mantovani, G.; Mariani, V.; Menichelli, M.; Rossi, A.; Santocchia, A.; Spiga, D.; Androsov, K.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Borrello, L.; Castaldi, R.; Ciocci, M. A.; Dell'Orso, R.; Fedi, G.; Giannini, L.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Manca, E.; Mandorli, G.; Messineo, A.; Palla, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Barone, L.; Cavallari, F.; Cipriani, M.; Daci, N.; Del Re, D.; Di Marco, E.; Diemoz, M.; Gelli, S.; Longo, E.; Margaroli, F.; Marzocchi, B.; Meridiani, P.; Organtini, G.; Paramatti, R.; Preiato, F.; Rahatlou, S.; Rovelli, C.; Santanastasio, F.; Amapane, N.; Arcidiacono, R.; Argiro, S.; Arneodo, M.; Bartosik, N.; Bellan, R.; Biino, C.; Cartiglia, N.; Cenna, F.; Costa, M.; Covarelli, R.; Degano, A.; Demaria, N.; Kiani, B.; Mariotti, C.; Maselli, S.; Migliore, E.; Monaco, V.; Monteil, E.; Monteno, M.; Obertino, M. M.; Pacher, L.; Pastrone, N.; Pelliccioni, M.; Pinna Angioni, G. L.; Ravera, F.; Romero, A.; Ruspa, M.; Sacchi, R.; Shchelina, K.; Sola, V.; Solano, A.; Staiano, A.; Traczyk, P.; Belforte, S.; Casarsa, M.; Cossutti, F.; Della Ricca, G.; Zanetti, A.; Kim, D. H.; Kim, G. N.; Kim, M. S.; Lee, J.; Lee, S.; Lee, S. W.; Moon, C. S.; Oh, Y. D.; Sekmen, S.; Son, D. C.; Yang, Y. C.; Lee, A.; Kim, H.; Moon, D. H.; Oh, G.; Brochero Cifuentes, J. A.; Goh, J.; Kim, T. J.; Cho, S.; Choi, S.; Go, Y.; Gyun, D.; Ha, S.; Hong, B.; Jo, Y.; Kim, Y.; Lee, K.; Lee, K. S.; Lee, S.; Lim, J.; Park, S. K.; Roh, Y.; Almond, J.; Kim, J.; Kim, J. S.; Lee, H.; Lee, K.; Nam, K.; Oh, S. B.; Radburn-Smith, B. C.; Seo, S. h.; Yang, U. K.; Yoo, H. D.; Yu, G. B.; Kim, H.; Kim, J. H.; Lee, J. S. H.; Park, I. C.; Choi, Y.; Hwang, C.; Lee, J.; Yu, I.; Dudenas, V.; Juodagalvis, A.; Vaitkus, J.; Ahmed, I.; Ibrahim, Z. A.; Md Ali, M. A. B.; Mohamad Idris, F.; Wan Abdullah, W. A. T.; Yusli, M. N.; Zolkapli, Z.; Reyes-Almanza, R.; Ramirez-Sanchez, G.; Duran-Osuna, M. C.; Castilla-Valdez, H.; De La Cruz-Burelo, E.; Heredia-De La Cruz, I.; Rabadan-Trejo, R. I.; Lopez-Fernandez, R.; Mejia Guisao, J.; Sanchez-Hernandez, A.; Carrillo Moreno, S.; Oropeza Barrera, C.; Vazquez Valencia, F.; Pedraza, I.; Salazar Ibarguen, H. A.; Uribe Estrada, C.; Morelos Pineda, A.; Krofcheck, D.; Butler, P. H.; Ahmad, A.; Ahmad, M.; Hassan, Q.; Hoorani, H. R.; Saddique, A.; Shah, M. A.; Shoaib, M.; Waqas, M.; Bialkowska, H.; Bluj, M.; Boimska, B.; Frueboes, T.; Górski, M.; Kazana, M.; Nawrocki, K.; Szleper, M.; Zalewski, P.; Bunkowski, K.; Byszuk, A.; Doroba, K.; Kalinowski, A.; Konecki, M.; Krolikowski, J.; Misiura, M.; Olszewski, M.; Pyskir, A.; Walczak, M.; Bargassa, P.; Beirão Da Cruz E Silva, C.; Di Francesco, A.; Faccioli, P.; Galinhas, B.; Gallinaro, M.; Hollar, J.; Leonardo, N.; Lloret Iglesias, L.; Nemallapudi, M. V.; Seixas, J.; Strong, G.; Toldaiev, O.; Vadruccio, D.; Varela, J.; Alexakhin, V.; Golunov, A.; Golutvin, I.; Gorbounov, N.; Gorbunov, I.; Kamenev, A.; Karjavin, V.; Lanev, A.; Malakhov, A.; Matveev, V.; Palichik, V.; Perelygin, V.; Savina, M.; Shmatov, S.; Shulha, S.; Skatchkov, N.; Smirnov, V.; Zarubin, A.; Ivanov, Y.; Kim, V.; Kuznetsova, E.; Levchenko, P.; Murzin, V.; Oreshkin, V.; Smirnov, I.; Sulimov, V.; Uvarov, L.; Vavilov, S.; Vorobyev, A.; Andreev, Yu.; Dermenev, A.; Gninenko, S.; Golubev, N.; Karneyeu, A.; Kirsanov, M.; Krasnikov, N.; Pashenkov, A.; Tlisov, D.; Toropin, A.; Epshteyn, V.; Gavrilov, V.; Lychkovskaya, N.; Popov, V.; Pozdnyakov, I.; Safronov, G.; Spiridonov, A.; Stepennov, A.; Toms, M.; Vlasov, E.; Zhokin, A.; Aushev, T.; Bylinkin, A.; Chistov, R.; Danilov, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Tarkovskii, E.; Andreev, V.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Terkulov, A.; Baskakov, A.; Belyaev, A.; Boos, E.; Bunichev, V.; Dubinin, M.; Dudko, L.; Ershov, A.; Gribushin, A.; Klyukhin, V.; Kodolova, O.; Lokhtin, I.; Miagkov, I.; Obraztsov, S.; Petrushanko, S.; Savrin, V.; Blinov, V.; Skovpen, Y.; Shtol, D.; Azhgirey, I.; Bayshev, I.; Bitioukov, S.; Elumakhov, D.; Kachanov, V.; Kalinin, A.; Konstantinov, D.; Mandrik, P.; Petrov, V.; Ryutin, R.; Sobol, A.; Troshin, S.; Tyurin, N.; Uzunian, A.; Volkov, A.; Adzic, P.; Cirkovic, P.; Devetak, D.; Dordevic, M.; Milosevic, J.; Rekovic, V.; Alcaraz Maestre, J.; Barrio Luna, M.; Cerrada, M.; Colino, N.; De La Cruz, B.; Delgado Peris, A.; Escalante Del Valle, A.; Fernandez Bedoya, C.; Fernández Ramos, J. P.; Flix, J.; Fouz, M. C.; Gonzalez Lopez, O.; Goy Lopez, S.; Hernandez, J. M.; Josa, M. I.; Moran, D.; Pérez-Calero Yzquierdo, A.; Puerta Pelayo, J.; Quintario Olmeda, A.; Redondo, I.; Romero, L.; Soares, M. S.; Álvarez Fernández, A.; Albajar, C.; de Trocóniz, J. F.; Missiroli, M.; Cuevas, J.; Erice, C.; Fernandez Menendez, J.; Gonzalez Caballero, I.; González Fernández, J. R.; Palencia Cortezon, E.; Sanchez Cruz, S.; Vischia, P.; Vizan Garcia, J. M.; Cabrillo, I. J.; Calderon, A.; Chazin Quero, B.; Curras, E.; Duarte Campderros, J.; Fernandez, M.; Garcia-Ferrero, J.; Gomez, G.; Lopez Virto, A.; Marco, J.; Martinez Rivero, C.; Martinez Ruiz del Arbol, P.; Matorras, F.; Piedra Gomez, J.; Rodrigo, T.; Ruiz-Jimeno, A.; Scodellaro, L.; Trevisani, N.; Vila, I.; Vilar Cortabitarte, R.; Abbaneo, D.; Akgun, B.; Auffray, E.; Baillon, P.; Ball, A. H.; Barney, D.; Bendavid, J.; Bianco, M.; Bloch, P.; Bocci, A.; Botta, C.; Camporesi, T.; Castello, R.; Cepeda, M.; Cerminara, G.; Chapon, E.; Chen, Y.; d'Enterria, D.; Dabrowski, A.; Daponte, V.; David, A.; De Gruttola, M.; De Roeck, A.; Deelen, N.; Dobson, M.; du Pree, T.; Dünser, M.; Dupont, N.; Elliott-Peisert, A.; Everaerts, P.; Fallavollita, F.; Franzoni, G.; Fulcher, J.; Funk, W.; Gigi, D.; Gilbert, A.; Gill, K.; Glege, F.; Gulhan, D.; Harris, P.; Hegeman, J.; Innocente, V.; Jafari, A.; Janot, P.; Karacheban, O.; Kieseler, J.; Knünz, V.; Kornmayer, A.; Kortelainen, M. J.; Krammer, M.; Lange, C.; Lecoq, P.; Lourenço, C.; Lucchini, M. T.; Malgeri, L.; Mannelli, M.; Martelli, A.; Meijers, F.; Merlin, J. A.; Mersi, S.; Meschi, E.; Milenovic, P.; Moortgat, F.; Mulders, M.; Neugebauer, H.; Ngadiuba, J.; Orfanelli, S.; Orsini, L.; Pape, L.; Perez, E.; Peruzzi, M.; Petrilli, A.; Petrucciani, G.; Pfeiffer, A.; Pierini, M.; Rabady, D.; Racz, A.; Reis, T.; Rolandi, G.; Rovere, M.; Sakulin, H.; Schäfer, C.; Schwick, C.; Seidel, M.; Selvaggi, M.; Sharma, A.; Silva, P.; Sphicas, P.; Stakia, A.; Steggemann, J.; Stoye, M.; Tosi, M.; Treille, D.; Triossi, A.; Tsirou, A.; Veckalns, V.; Verweij, M.; Zeuner, W. D.; Bertl, W.; Caminada, L.; Deiters, K.; Erdmann, W.; Horisberger, R.; Ingram, Q.; Kaestli, H. C.; Kotlinski, D.; Langenegger, U.; Rohe, T.; Wiederkehr, S. A.; Backhaus, M.; Bäni, L.; Berger, P.; Bianchini, L.; Casal, B.; Dissertori, G.; Dittmar, M.; Donegà, M.; Dorfer, C.; Grab, C.; Heidegger, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Klijnsma, T.; Lustermann, W.; Mangano, B.; Marionneau, M.; Meinhard, M. T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Reichmann, M.; Sanz Becerra, D. A.; Schönenberger, M.; Shchutska, L.; Tavolaro, V. R.; Theofilatos, K.; Vesterbacka Olsson, M. L.; Wallny, R.; Zhu, D. H.; Aarrestad, T. K.; Amsler, C.; Canelli, M. F.; De Cosa, A.; Del Burgo, R.; Donato, S.; Galloni, C.; Hreus, T.; Kilminster, B.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Schweiger, K.; Seitz, C.; Takahashi, Y.; Zucchetta, A.; Candelise, V.; Doan, T. H.; Jain, Sh.; Khurana, R.; Kuo, C. M.; Lin, W.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chao, Y.; Chen, K. F.; Chen, P. H.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Paganis, E.; Psallidas, A.; Steen, A.; Tsai, J. f.; Asavapibhop, B.; Kovitanggoon, K.; Singh, G.; Srimanobhas, N.; Bakirci, M. N.; Bat, A.; Boran, F.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. E.; Kara, O.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Ozturk, S.; Polatoz, A.; Tok, U. G.; Topakli, H.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Bilin, B.; Karapinar, G.; Ocalan, K.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Tekten, S.; Yetkin, E. A.; Agaras, M. N.; Atay, S.; Cakir, A.; Cankocak, K.; Köseoglu, I.; Grynyov, B.; Levchuk, L.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Davignon, O.; Flacher, H.; Goldstein, J.; Heath, G. P.; Heath, H. F.; Kreczko, L.; Newbold, D. M.; Paramesvaran, S.; Sakuma, T.; Seif El Nasr-storey, S.; Smith, D.; Smith, V. J.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Calligaris, L.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Linacre, J.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Auzinger, G.; Bainbridge, R.; Borg, J.; Breeze, S.; Buchmuller, O.; Bundock, A.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Elwood, A.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Matsushita, T.; Nash, J.; Nikitenko, A.; Palladino, V.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Shtipliyski, A.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wardle, N.; Winterbottom, D.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Teodorescu, L.; Turner, M.; Zahid, S.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Smith, C.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hadley, M.; Hakala, J.; Heintz, U.; Hogan, J. M.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Lee, J.; Mao, Z.; Narain, M.; Pazzini, J.; Piperov, S.; Sagir, S.; Syarif, R.; Yu, D.; Band, R.; Brainerd, C.; Breedon, R.; Burns, D.; Calderon De La Barca Sanchez, M.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Stolp, D.; Tos, K.; Tripathi, M.; Wang, Z.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Regnard, S.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Karapostoli, G.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Si, W.; Wang, L.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Gilbert, D.; Hashemi, B.; Holzner, A.; Klein, D.; Kole, G.; Krutelyov, V.; Letts, J.; Macneill, I.; Masciovecchio, M.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; Golf, F.; Gouskos, L.; Heller, R.; Incandela, J.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bornheim, A.; Lawhorn, J. M.; Newman, H. B.; Nguyen, T.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhang, Z.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Mudholkar, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Patterson, J. R.; Quach, D.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Abdullin, S.; Albrow, M.; Alyari, M.; Apollinari, G.; Apresyan, A.; Apyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cerati, G. B.; Cheung, H. W. K.; Chlebana, F.; Cremonesi, M.; Duarte, J.; Elvira, V. D.; Freeman, J.; Gecse, Z.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Schneider, B.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Field, R. D.; Furic, I. K.; Gleyzer, S. V.; Joshi, B. M.; Konigsberg, J.; Korytov, A.; Kotov, K.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Shi, K.; Sperka, D.; Terentyev, N.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Joshi, Y. R.; Linn, S.; Markowitz, P.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Martinez, G.; Perry, T.; Prosper, H.; Saha, A.; Santra, A.; Sharma, V.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Tonjes, M. B.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Royon, C.; Sanders, S.; Schmitz, E.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Eno, S. C.; Feng, Y.; Ferraioli, C.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Hu, M.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Hiltbrand, J.; Kalafut, S.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Turkewitz, J.; Wadud, M. A.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Li, W.; Loukas, N.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Siddireddy, P.; Smith, G.; Taroni, S.; Wayne, M.; Wightman, A.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Higginbotham, S.; Kalogeropoulos, A.; Lange, D.; Luo, J.; Marlow, D.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Malik, S.; Norberg, S.; Barker, A.; Barnes, V. E.; Das, S.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Peng, C. C.; Qiu, H.; Schulte, J. F.; Sun, J.; Wang, F.; Xie, W.; Cheng, T.; Parashar, N.; Stupak, J.; Adair, A.; Chen, Z.; Ecklund, K. M.; Freed, S.; Geurts, F. J. M.; Guilbaud, M.; Kilpatrick, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Shi, W.; Tu, Z.; Zabel, J.; Zhang, A.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Ciesielski, R.; Goulianos, K.; Mesropian, C.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Mengke, T.; Muthumuni, S.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Padeken, K.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Joyce, M.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Wang, Y.; Wolfe, E.; Xia, F.; Harr, R.; Karchin, P. E.; Poudyal, N.; Sturdy, J.; Thapa, P.; Zaleski, S.; Brodski, M.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.; CMS Collaboration

2018-02-01

A search for new physics is presented in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from b quarks, and missing transverse momentum (pTmiss). The search uses proton-proton collision data at √{s }=13 TeV amounting to 35.9 fb-1 of integrated luminosity collected using the CMS detector in 2016. Hypothetical signal events are efficiently separated from the dominant t t ¯ background with requirements on pTmiss and transverse-mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced top squarks. For top squarks, decaying exclusively to a top quark and a neutralino, exclusion limits are placed at 95% confidence level on the mass of the lightest top squark up to 800 GeV and on the lightest neutralino up to 360 GeV. These results, combined with searches in the single-lepton and all-jet final states, raise the exclusion limits up to 1050 GeV for the lightest top squark and up to 500 GeV for the lightest neutralino. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1300 GeV for top squarks and up to 800 GeV for the lightest neutralino. The results are also interpreted in a simplified model with a dark matter (DM) particle coupled to the top quark through a scalar or pseudoscalar mediator. For light DM, mediator masses up to 100 (50) GeV are excluded for scalar (pseudoscalar) mediators. The result for the scalar mediator achieves some of the most stringent limits to date in this model.

Elevated transition temperature in Ge doped VO2 thin films

NASA Astrophysics Data System (ADS)

Krammer, Anna; Magrez, Arnaud; Vitale, Wolfgang A.; Mocny, Piotr; Jeanneret, Patrick; Guibert, Edouard; Whitlow, Harry J.; Ionescu, Adrian M.; Schüler, Andreas

2017-07-01

Thermochromic GexV1-xO2+y thin films have been deposited on Si (100) substrates by means of reactive magnetron sputtering. The films were then characterized by Rutherford backscattering spectrometry (RBS), four-point probe electrical resistivity measurements, X-ray diffraction, and atomic force microscopy. From the temperature dependent resistivity measurements, the effect of Ge doping on the semiconductor-to-metal phase transition in vanadium oxide thin films was investigated. The transition temperature was shown to increase significantly upon Ge doping (˜95 °C), while the hysteresis width and resistivity contrast gradually decreased. The precise Ge concentration and the film thickness have been determined by RBS. The crystallinity of phase-pure VO2 monoclinic films was confirmed by XRD. These findings make the use of vanadium dioxide thin films in solar and electronic device applications—where higher critical temperatures than 68 °C of pristine VO2 are needed—a viable and promising solution.

Microstructural Characteristics of GeSbTe Thin Films Grown by RF Sputtering

NASA Astrophysics Data System (ADS)

Nelson, M. J.; Inglefield, C. E.; Olson, J. K.; Li, H.; Taylor, P. C.

2004-10-01

Thin films of GeSbTe are of interest due to their potential use in rewritable optical data storage media and reconfigurable electronics. The amorphous and crystalline phases of GeSbTe exhibit very different reflectivity and electrical conductivity. Films of nominally amorphous Ge_2Sb_2Te5 were grown to various thicknesses using RF sputtering on quartz substrates. The surfaces of the films were analyzed using Atomic Force Microscopy (AFM) and surface roughness measurements were taken. The thicker films had a truly isotropic surface while the thinnest films displayed crystalline features, such as angular steps. Conductivity measurements of the films in both coplanar and sandwich geometries correlate with the AFM data and indicate a high degree of crystallinity during the initial stages of growth. This work was supported by the Air Force Research Laboratory under grant number F29601-03-01-0229 and by Weber State University through the Phyllis Crosby Gardner fellowship.

Magnetic properties of ultrathin tetragonal Heusler D022-Mn3Ge perpendicular-magnetized films

NASA Astrophysics Data System (ADS)

Sugihara, A.; Suzuki, K. Z.; Miyazaki, T.; Mizukami, S.

2015-05-01

We investigated the crystal structure and magnetic properties of Manganese-germanium (Mn3Ge) films having the tetragonal D022 structure, with varied thicknesses (5-130 nm) prepared on chromium (Cr)-buffered single crystal MgO(001) substrates. A crystal lattice elongation in the in-plane direction, induced by the lattice mismatch between the D022-Mn3Ge and the Cr buffer layer, increased with decreasing thickness of the D022-Mn3Ge layer. The films exhibited clear magnetic hysteresis loops with a squareness ratio close to unity, and a step-like magnetization reversal even at a 5-nm thickness under an external field perpendicular to the film's plane. The uniaxial magnetic anisotropy constant of the films showed a reduction to less than 10 Merg/cm3 in the small thickness range (≤20 nm), likely due to the crystal lattice elongation in the in-plane direction.

Optical and electrical characterization of high resistivity semiconductors for constant-bias microbolometer devices

NASA Astrophysics Data System (ADS)

Saint John, David B.

The commercial market for uncooled infrared imaging devices has expanded in the last several decades, following the declassification of pulse-biased microbolometer-based focal plane arrays (FPAs) using vanadium oxide as the sensing material. In addition to uncooled imaging platforms based on vanadium oxide, several constant-bias microbolometer FPAs have been developed using doped hydrogenated amorphous silicon (a-Si:H) as the active sensing material. While a-Si:H and the broader Si1-xGex:H system have been studied within the context of photovoltaic (PV) devices, only recently have these materials been studied with the purpose of qualifying and optimizing them for potential use in microbolometer applications, which demand thinner films deposited onto substrates different than those used in PV. The behavior of Ge:H is of particular interest for microbolometers due to its intrinsically low resistivity without the introduction of dopants, which alter the growth behavior and frustrate any attempt to address the merits of protocrystalline a-Ge:H. This work reports the optical, microstructural, and electrical characterization and qualification of a variety of Si:H, Si1-xGex:H, and Ge:H films deposited using a plasma enhanced chemical vapor deposition (PECVD) process, including a-Ge:H films which exhibit high TCR (4-6 -%/K) and low 1/f noise at resistivities of interest for microbolometers (4000 -- 6000 O cm). Thin film deposition has been performed simultaneously with real-time optical characterization of the growth evolution dynamics, providing measurement of optical properties and surface roughness evolutions relevant to controlling the growth process for deliberate variations in film microstructure. Infrared spectroscopic ellipsometry has been used to characterize the Si-H and Ge-H absorption modes allowing assessment of the hydrogen content and local bonding behavior in thinner films than measured traditionally. This method allows IR absorption analysis of hydrogen bonding and other IR modes to be extended to arbitrary substrates, including absorbing and/or device-like substrate configurations not amenable to traditional methods of assessing hydrogen related absorption using infrared transmission measurements. In addition to novel optical assessments of hydrogen in Si1-xGe x:H films, the role of carrier type in a-Si:H has been studied, with n-type material providing a consistently higher TCR and 1/f noise character than p-type material for films of similar resistivity. As the introduction of dopant gas complicates microstructural growth, assessment of undoped material was performed, finding that only Ge-rich films possess suitable resitivities for electrical measurement. The inclusion of nanocrystalline material into otherwise amorphous films has been explored in both Si:H and Ge:H, finding that decreases in resistivity and TCR were not accompanied by a decrease in the 1/f noise character. This suggests that mixed (a+nc) Si1-xGex:H material may be less suitable for microbolometer applications than optimized amorphous material.

Progress toward the development of dual junction GaAs/Ge solar cells

NASA Technical Reports Server (NTRS)

Lillington, D. R.; Krut, D. D.; Cavicchi, B. T.; Ralph, E.; Chung, M.

1991-01-01

Large area GaAs/Ge cells offer substantial promise for increasing the power output from existing silicon solar array designs and for providing an enabled technology for missions hitherto impossible using silicon. Single junction GaAs/Ge cells offer substantial advantages in both size, weight, and cost compared to GaAs cells but the efficiency is limited to approximately 19.2 to 20 percent AMO. The thermal absorptance of GaAs/Ge cells is also worse than GaAs/GaAs cells (0.88 vs 0.81 typ.) due to the absorption in the Ge substrate. On the other hand dual junction GaAs/Ge cells offer efficiencies up to ultimately 24 percent AMO in sizes up to 8 x 8 cm but there are still technological issues remaining to achieve current matching in the GaAs and Ge cells. This can be achieved through tuned antireflection (AR) coatings, improved quality of the GaAs growth, improved quality Ge wafers and the use of a Back Surface Field (BSF)/Back Surface Reflector (BSR) in the Ge cell. Although the temperature coefficients of efficiency and voltage are higher for dual junction GaAs/Ge cells, it has been shown elsewhere that for typical 28 C cell efficiencies of 22 percent (dual junction) vs 18.5 percent (single junction) there is a positive power tradeoff up to temperatures as high as 120 C. Due to the potential ease of fabrication of GaAs/Ge dual junction cells there is likely to be only a small cost differential compared to single junction cells.

p-barp interactions at 2. 32 GeV/c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C.K.; Fields, T.; Rhines, D.S.

1978-01-01

A bubble-chamber experiment based on 304 000 events of p-barp interactions at 2.32 GeV/c is described. The film was automatically scanned and measured by the POLLY II system. Details of the data-analysis methods are given. We report results on cross sections for constrained final states, tests of C invariance, and inclusive pion and rho/sup 0/ multiplicity parameters for annihilation final states.

Numerical investigations of failure in EB-PVD thermal barrier coating systems

NASA Astrophysics Data System (ADS)

Glynn, Michael L.

Thermal barrier coating (TBC) systems are used in high temperature applications in turbine engines. TBCs are applied on superalloy substrates and are multilayered coatings comprised of a metallic bond coat, a thermally grown oxide (TGO) and a ceramic top coat. They provide thermal protection for the superalloy substrate and are considered to hold the greatest potential for increased operating temperatures. Failure of the TBC system most commonly occurs as a result of large scale buckling and spallation. The buckling is a consequence of many small-scale delaminations that arise in the top coat above local imperfections in the TGO, and durability of the TBC system is governed by a sequence of crack nucleation, propagation and coalescence. The numerical investigations that are employed in this dissertation are used to determine the stress development near the imperfections and are based on microstructural observations and measured material properties of TBC test buttons supplied by GE Aircraft Engines. The test buttons were subject to thermal cycling at GE and cycled to different percentages of TBC life. Numerical simulations of two different types of TBC tests are used to show that the top coat out-of-plane stress increases with a decrease of the substrate radius of curvature and a decrease in the heating rate. An inherent scaling parameter in the TBC system is identified and used to demonstrate that the stress developed in the top coat is governed by the evolution of an imperfection in the TGO. The effect of a martensitic phase transformation in the bond coat, related to a change in bond coat chemistry, is shown to significantly increase the top coat out-of-plane tensile stress. Finally, a subsurface crack is simulated in the top coat and used to determine the influence of the bond coat on failure of the TBC system. While the bond coat inelastic properties are the most important factors in determining the extent of the crack opening displacement, the bond coat martensitic phase transformation governs when the crack propagates. The crack propagates during heat-up when the martensitic phase transformation is included, and it propagates during cool-down when the transformation is not included.

Photoluminescence of Gallium Phosphide-Based Nanostructures with Germanium Quantum Dots, Grown by Liquid-Phase Epitaxy

NASA Astrophysics Data System (ADS)

Maronchuk, I. I.; Sanikovich, D. D.; Velchenko, A. A.

2017-11-01

We have used liquid-phase epitaxy with pulsed substrate cooling using two structural designs to grow samples of nanoheteroepitaxial structures with Ge quantum dots in a GaP matrix on Si substrates. We have measured the photoluminescence spectra of the samples at temperatures of 77 K and 300 K with excitation by laser emission at λ = 4880 Å and 5145 Å. We draw conclusions concerning the factors influencing the spectrum and intensity of emission for nanostructures with quantum dots. It was found that in order to reduce nonradiative recombination in multilayer p-n structures, we need to create quantum dot arrays inside p and n regions rather than in the central portion of the depletion layer of the p-n junction. We show that the theoretical energies for Ge quantum dots of the calculated sizes are comparable with the energies of their photoluminescence maxima.

Low-temperature magnetotransport in Si/SiGe heterostructures on 300 mm Si wafers

NASA Astrophysics Data System (ADS)

Scappucci, Giordano; Yeoh, L.; Sabbagh, D.; Sammak, A.; Boter, J.; Droulers, G.; Kalhor, N.; Brousse, D.; Veldhorst, M.; Vandersypen, L. M. K.; Thomas, N.; Roberts, J.; Pillarisetty, R.; Amin, P.; George, H. C.; Singh, K. J.; Clarke, J. S.

Undoped Si/SiGe heterostructures are a promising material stack for the development of spin qubits in silicon. To deploy a qubit into high volume manufacturing in a quantum computer requires stringent control over substrate uniformity and quality. Electron mobility and valley splitting are two key electrical metrics of substrate quality relevant for qubits. Here we present low-temperature magnetotransport measurements of strained Si quantum wells with mobilities in excess of 100000 cm2/Vs fabricated on 300 mm wafers within the framework of advanced semiconductor manufacturing. These results are benchmarked against the results obtained in Si quantum wells deposited on 100 mm Si wafers in an academic research environment. To ensure rapid progress in quantum wells quality we have implemented fast feedback loops from materials growth, to heterostructure FET fabrication, and low temperature characterisation. On this topic we will present recent progress in developing a cryogenic platform for high-throughput magnetotransport measurements.

Template-free preparation of crystalline Ge nanowire film electrodes via an electrochemical liquid-liquid-solid process in water at ambient pressure and temperature for energy storage.

PubMed

Gu, Junsi; Collins, Sean M; Carim, Azhar I; Hao, Xiaoguang; Bartlett, Bart M; Maldonado, Stephen

2012-09-12

The direct electrodeposition of crystalline germanium (Ge) nanowire film electrodes from an aqueous solution of dissolved GeO(2) using discrete 'flux' nanoparticles capable of dissolving Ge(s) has been demonstrated. Electrodeposition of Ge at inert electrode substrates decorated with small (<100 nm), discrete indium (In) nanoparticles resulted in crystalline Ge nanowire films with definable nanowire diameters and densities without the need for a physical or chemical template. The Ge nanowires exhibited strong polycrystalline character as-deposited, with approximate crystallite dimensions of 20 nm and a mixed orientation of the crystallites along the length of the nanowire. Energy dispersive spectroscopic elemental mapping of individual Ge nanowires showed that the In nanoparticles remained at the base of each nanowire, indicating good electrical communication between the Ge nanowire and the underlying conductive support. As-deposited Ge nanowire films prepared on Cu supports were used without further processing as Li(+) battery anodes. Cycling studies performed at 1 C (1624 mA g(-1)) indicated the native Ge nanowire films supported stable discharge capacities at the level of 973 mA h g(-1), higher than analogous Ge nanowire film electrodes prepared through an energy-intensive vapor-liquid-solid nanowire growth process. The cumulative data show that ec-LLS is a viable method for directly preparing a functional, high-activity nanomaterials-based device component. The work presented here is a step toward the realization of simple processes that make fully functional energy conversion/storage technologies based on crystalline inorganic semiconductors entirely through benchtop, aqueous chemistry and electrochemistry without time- or energy-intensive process steps.

Density functional theory study of dopant effect on formation energy of intrinsic point defects in germanium crystals

NASA Astrophysics Data System (ADS)

Yamaoka, S.; Kobayashi, K.; Sueoka, K.; Vanhellemont, J.

2017-09-01

During the last decade the use of single crystal germanium (Ge) layers and structures in combination with silicon (Si) substrates has led to a revival of defect research on Ge. Ge is used because of the much higher carrier mobility compared to Si, allowing to design devices operating at much higher frequencies. A major issue for the use of Ge single crystal wafers is the fact that all Czochralski-grown Ge (CZ-Ge) crystals are vacancy-rich and contain vacancy clusters that are much larger than the ones in Si. In contrast to Si, control of intrinsic point defect concentrations has not yet been realized at the same level in Ge crystals due to the lack of experimental data especially on dopant effects. In this study, we have evaluated with density functional theory (DFT) calculations the dopant effect on the formation energy (Ef) of the uncharged vacancy (V) and self-interstitial (I) in Ge and compared the results with those for Si. The dependence of the total thermal equilibrium concentrations of point defects (sum of free V or I and V or I paired with dopant atoms) at melting temperature on the type and concentration of various dopants is obtained. It was found that (1) Ge crystals will be more V-rich by Tl, In, Sb, Sn, As and P doping, (2) Ge crystals will be more I-rich by Ga, C and B doping, (3) Si doping has negligible impact. The dopant impact on Ef of V and I in Ge has a narrower range and is smaller than that in Si. The obtained results are useful to control grown-in V and I concentrations, and will perhaps also allow to develop defect-free ;perfect; Ge crystals.

Selective epitaxy using the gild process

DOEpatents

Weiner, Kurt H.

1992-01-01

The present invention comprises a method of selective epitaxy on a semiconductor substrate. The present invention provides a method of selectively forming high quality, thin GeSi layers in a silicon circuit, and a method for fabricating smaller semiconductor chips with a greater yield (more error free chips) at a lower cost. The method comprises forming an upper layer over a substrate, and depositing a reflectivity mask which is then removed over selected sections. Using a laser to melt the unmasked sections of the upper layer, the semiconductor material in the upper layer is heated and diffused into the substrate semiconductor material. By varying the amount of laser radiation, the epitaxial layer is formed to a controlled depth which may be very thin. When cooled, a single crystal epitaxial layer is formed over the patterned substrate. The present invention provides the ability to selectively grow layers of mixed semiconductors over patterned substrates such as a layer of Ge.sub.x Si.sub.1-x grown over silicon. Such a process may be used to manufacture small transistors that have a narrow base, heavy doping, and high gain. The narrowness allows a faster transistor, and the heavy doping reduces the resistance of the narrow layer. The process does not require high temperature annealing; therefore materials such as aluminum can be used. Furthermore, the process may be used to fabricate diodes that have a high reverse breakdown voltage and a low reverse leakage current.

(Tl, Sb) and (Tl, Bi) binary surface reconstructions on Ge(111) substrate

NASA Astrophysics Data System (ADS)

Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Yakovlev, A. A.; Mihalyuk, A. N.; Zotov, A. V.; Saranin, A. A.

2018-03-01

2D compounds made of Group-III and Group-V elements on the surface of silicon and germanium attract considerable attention due to prospects of creating III-V binary monolayers, which are predicted to hold advanced physical properties. In the present work, we have investigated two such systems, (Tl, Sb)/Ge(111) and (Tl, Bi)/Ge(111) using scanning tunneling microscopy, low energy electron diffraction observations and density-functional-theory calculations. In addition to the previously reported surface structures of 2D (Tl, Sb) and (Tl, Bi) compounds on Si(111), we found new ones, namely, √{ 7} × √{ 7} and 3 × 3. Formation processes and plausible models of their atomic arrangements are discussed.

Cooperative growth phenomena in silicon/germanium low-temperature epitaxy

NASA Astrophysics Data System (ADS)

Meyerson, Bernard S.; Uram, Kevin J.; LeGoues, Francoise K.

1988-12-01

A series of Si:Ge alloys and structures has been prepared by ultrahigh-vacuum chemical vapor deposition. Alloys of composition 0≤Ge/Si≤0.20 are readily deposited at T=550 °C. Commensurate, defect-free strained layers are deposited up to a critical thickness, whereupon the accumulated stress in the films is accommodated by the formation of dislocation networks in the substrate wafers. A cooperative growth phenomenon is observed where the addition of 10% germane to the gaseous deposition source accelerates silane's heterogeneous reaction rate by a factor of 25. A model is proposed where Ge acts as a desorption center for mobile hydrogen adatoms on the Si[100] surface, accelerating heterogeneous silane pyrolysis by the enhanced availability of chemisorption sites.

Electron mobility enhancement in epitaxial multilayer Si-Si/1-x/Ge/x/ alloy films on /100/Si

NASA Technical Reports Server (NTRS)

Manasevit, H. M.; Gergis, I. S.; Jones, A. B.

1982-01-01

Enhanced Hall-effect mobilities have been measured in epitaxial (100)-oriented multilayer n-type Si/Si(1-x)Ge(x) films grown on single-crystal Si substrates by chemical vapor deposition. Mobilities from 20 to 40% higher than that of epitaxial Si layers and about 100% higher than that of epitaxial SiGe layers on Si were measured for the doping range 8 x 10 to the 15th to 10 to the 17th/cu cm. No mobility enhancement was observed in multilayer p-type (100) films and n-type (111)-oriented films. Experimental studies included the effects upon film properties of layer composition, total film thickness, doping concentrations, layer thickness, and growth temperature.

Post-growth annealing of germanium-tin alloys using pulsed excimer laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lanxiang; Wang, Wei; Zhou, Qian

2015-07-14

We investigate the impact of pulsed excimer laser anneal on fully strained germanium-tin alloys (Ge{sub 1−x}Sn{sub x}) epitaxially grown on Ge substrate by molecular beam epitaxy. Using atomic force microscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, the morphological and compositional evolution of Ge{sub 1−x}Sn{sub x} with Sn content up to 17% after annealing using various conditions is studied. Ge{sub 0.83}Sn{sub 0.17} samples annealed at 80 mJ/cm{sup 2} or 150 mJ/cm{sup 2} have no observable changes with respect to the as-grown sample. However, Ge{sub 0.83}Sn{sub 0.17} samples annealed at 250 mJ/cm{sup 2} or 300 mJ/cm{sup 2} have Sn-richmore » islands on the surface, which is due to Sn segregation in the compressively strained epitaxial film. For Ge{sub 0.89}Sn{sub 0.11}, significant Sn redistribution occurs only when annealed at 300 mJ/cm{sup 2}, indicating that it has better thermal stability than Ge{sub 0.83}Sn{sub 0.17}. A mechanism is proposed to explain the formation of Sn-rich islands and Sn-depleted regions.« less

Atomic structures of B20 FeGe thin films grown on the Si(111) surface

NASA Astrophysics Data System (ADS)

Kim, Wondong; Noh, Seungkyun; Yoon, Jisoo; Kim, Young Heon; Lee, Inho; Kim, Jae-Sung; Hwang, Chanyong

We investigated the growth and atomic structures of FeGe thin films on the Si (111) surface by using scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). The 2 5nm- thick FeGe thin films were prepared on the clean Si(111) 7x7 surface by co-deposition of Fe and Ge from separated electron-beam evaporators. With direct deposition on the substrate at the temperature above 550 K, the surface of FeGe films was not smooth and consisted of coarse grains. By the combination of room-temperature annealing and post-annealing process around 800 K, the structure of FeGe thin films evolved into the well crystalized structures. Atom-resolved STM images revealed that there are at least four different surface terminations. We constructed atomic models for each surface terminations based on the bulk atomic arrangement of a B20 chiral structure and confirmed that the observed STM images are successfully reproduced by using computational simulations employing Vienna Ab Initio Simulation package (VASP) with a B20 chiral structure model. TEM cross-sectional images also support our atomic models by revealing clearly the characteristic zigzag features of B20 structures of FeGe(111) thin films.

Thermal transport through Ge-rich Ge/Si superlattices grown on Ge(0 0 1)

NASA Astrophysics Data System (ADS)

Thumfart, L.; Carrete, J.; Vermeersch, B.; Ye, N.; Truglas, T.; Feser, J.; Groiss, H.; Mingo, N.; Rastelli, A.

2018-01-01

The cross-plane thermal conductivities of Ge-rich Si/Ge superlattices have been measured using both time-domain thermoreflectance and the differential 3ω method. The superlattices were grown by molecular beam epitaxy on Ge(0 0 1) substrates. Crystal quality and structural information were investigated by x-ray diffractometry and transmission electron microscopy. The influence of segregation during growth on the composition profiles was modeled using the experimental growth temperatures and deposition rates. Those profiles were then employed to obtain parameter-free theoretical estimates of the thermal conductivity by combining first-principles calculations, Boltzmann transport theory and phonon Green’s functions. Good agreement between theory and experiment is observed. The thermal conductivity shows a strong dependence on the composition and the thickness of the samples. Moreover, the importance of the composition profile is reflected in the fact that the thermal conductivity of the superlattices is considerably lower than predicted values for alloys with the same average composition and thickness. Measurement on different samples with the same Si layer thickness and number of periods, but different Ge layer thickness, show that the thermal resistance is only weakly dependent on the Ge layers. We analyze this phenomenon based on the first-principles mode, and build an approximate parametrization showing that, in this regime, the resistivity of a SL is roughly linear on the amount of Si.

Rail integrity alert system (RIAS) feature discrimination : final report.

DOT National Transportation Integrated Search

2016-08-01

This report describes GE Global Researchs research, in partnership with GE Transportation, into developing and deploying : algorithms for a locomotive-based inductive sensing system that has a very high probability of detecting broken rails with v...

Search for pair-produced massive coloured scalars in four-jet final states with the ATLAS detector in proton–proton collisions at $$\\sqrt{s} = 7\\ \\mbox{TeV}$$

DOE PAGES

Aad, G.; Abajyan, T.; Abbott, B.; ...

2013-01-15

A search for pair-produced massive coloured scalar particles decaying to a four-jet final state is performed by the ATLAS experiment at the LHC in proton–proton collisions at √s = 7 TeV. The analysed data sample corresponds to an integrated luminosity of 4.6 fb -1. No deviation from the Standard Model is observed in the invariant mass spectrum of the two-jet pairs. A limit on the scalar gluon pair production cross section of 70 pb (10 pb) is obtained at the 95 % confidence level for a scalar gluon mass of 150 GeV (350 GeV). Lastly, interpreting these results as massmore » limits on scalar gluons, masses ranging from 150 GeV to 287 GeV are excluded at the 95 % confidence level.« less

Search for direct top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in sqrt[s] = 7 TeV pp collisions using 4.7 fb(-10 of ATLAS data.

PubMed

Aad, G; Abajyan, T; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdelalim, A A; Abdinov, O; Aben, R; Abi, B; Abolins, M; Abouzeid, O S; Abramowicz, H; Abreu, H; Acharya, B S; Adamczyk, L; Adams, D L; Addy, T N; Adelman, J; Adomeit, S; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, J A; Agustoni, M; Aharrouche, M; Ahlen, S P; Ahles, F; Ahmad, A; Ahsan, M; Aielli, G; Akdogan, T; Akesson, T P A; Akimoto, G; Akimov, A V; Alam, M S; Alam, M A; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Allbrooke, B M M; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alonso, F; Altheimer, A D; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amelung, C; Ammosov, V V; Amorim, A; Amram, N; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aoun, S; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Arfaoui, S; Arguin, J-F; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Arnault, C; Artamonov, A; Artoni, G; Arutinov, D; Asai, S; Asfandiyarov, R; Ask, S; Asman, B; Asquith, L; Assamagan, K; Astbury, A; Atkinson, M; Aubert, B; Auge, E; Augsten, K; Aurousseau, M; Avolio, G; Avramidou, R; Axen, D; Azuelos, G; Azuma, Y; Baak, M A; Baccaglioni, G; Bacci, C; Bach, A M; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Badescu, E; Bagnaia, P; Bahinipati, S; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, M D; Baker, S; Banas, E; Banerjee, P; Banerjee, Sw; Banfi, D; Bangert, A; Bansal, V; Bansil, H S; Barak, L; Baranov, S P; Barbaro Galtieri, A; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Barrillon, P; Bartoldus, R; Barton, A E; Bartsch, V; Basye, A; Bates, R L; Batkova, L; Batley, J R; Battaglia, A; Battistin, M; Bauer, F; Bawa, H S; Beale, S; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, A K; Becker, S; Beckingham, M; Becks, K H; Beddall, A J; Beddall, A; Bedikian, S; Bednyakov, V A; Bee, C P; Beemster, L J; Begel, M; Behar Harpaz, S; Beimforde, M; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellina, F; Bellomo, M; Belloni, A; Beloborodova, O; Belotskiy, K; Beltramello, O; Benary, O; Benchekroun, D; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Benoit, M; Bensinger, J R; Benslama, K; Bentvelsen, S; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernat, P; Bernhard, R; Bernius, C; Berry, T; Bertella, C; Bertin, A; Bertolucci, F; Besana, M I; Besjes, G J; Besson, N; Bethke, S; Bhimji, W; Bianchi, R M; Bianco, M; Biebel, O; Bieniek, S P; Bierwagen, K; Biesiada, J; Biglietti, M; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biscarat, C; Bittner, B; Black, K M; Blair, R E; Blanchard, J-B; Blanchot, G; Blazek, T; Bloch, I; Blocker, C; Blocki, J; Blondel, A; Blum, W; Blumenschein, U; Bobbink, G J; Bobrovnikov, V B; Bocchetta, S S; Bocci, A; Boddy, C R; Boehler, M; Boek, J; Boelaert, N; Bogaerts, J A; Bogdanchikov, A; Bogouch, A; Bohm, C; Bohm, J; Boisvert, V; Bold, T; Boldea, V; Bolnet, N M; Bomben, M; Bona, M; Boonekamp, M; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borjanovic, I; Borri, M; Borroni, S; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Boterenbrood, H; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Bousson, N; Boveia, A; Boyd, J; Boyko, I R; Bozovic-Jelisavcic, I; Bracinik, J; Branchini, P; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brazzale, S F; Brelier, B; Bremer, J; Brendlinger, K; Brenner, R; Bressler, S; Britton, D; Brochu, F M; Brock, I; Brock, R; Broggi, F; Bromberg, C; Bronner, J; Brooijmans, G; Brooks, T; Brooks, W K; Brown, G; Brown, H; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Buanes, T; Buat, Q; Bucci, F; Buchanan, J; Buchholz, P; Buckingham, R M; Buckley, A G; Buda, S I; Budagov, I A; Budick, B; Büscher, V; Bugge, L; Bulekov, O; Bundock, A C; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Bussey, P; Buszello, C P; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Buttinger, W; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G; Calfayan, P; Calkins, R; Caloba, L P; Caloi, R; Calvet, D; Calvet, S; Camacho Toro, R; Camarri, P; Cameron, D; Caminada, L M; Caminal Armadans, R; Campana, S; Campanelli, M; Canale, V; Canelli, F; Canepa, A; Cantero, J; Cantrill, R; Capasso, L; Capeans Garrido, M D M; Caprini, I; Caprini, M; Capriotti, D; Capua, M; Caputo, R; Cardarelli, R; Carli, T; Carlino, G; Carminati, L; Caron, B; Caron, S; Carquin, E; Carrillo Montoya, G D; Carter, A A; Carter, J R; Carvalho, J; Casadei, D; Casado, M P; Cascella, M; Caso, C; Castaneda Hernandez, A M; Castaneda-Miranda, E; Castillo Gimenez, V; Castro, N F; Cataldi, G; Catastini, P; Catinaccio, A; Catmore, J R; Cattai, A; Cattani, G; Caughron, S; Cavaliere, V; Cavalleri, P; Cavalli, D; Cavalli-Sforza, M; Cavasinni, V; Ceradini, F; Cerqueira, A S; Cerri, A; Cerrito, L; Cerutti, F; Cetin, S A; Chafaq, A; Chakraborty, D; Chalupkova, I; Chan, K; Chang, P; Chapleau, B; Chapman, J D; Chapman, J W; Chareyre, E; Charlton, D G; Chavda, V; Chavez Barajas, C A; Cheatham, S; Chekanov, S; Chekulaev, S V; Chelkov, G A; Chelstowska, M A; Chen, C; Chen, H; Chen, S; Chen, X; Chen, Y; Cheplakov, A; Cherkaoui El Moursli, R; Chernyatin, V; Cheu, E; Cheung, S L; Chevalier, L; Chiefari, G; Chikovani, L; Childers, J T; Chilingarov, A; Chiodini, G; Chisholm, A S; Chislett, R T; Chitan, A; Chizhov, M V; Choudalakis, G; Chouridou, S; Christidi, I A; Christov, A; Chromek-Burckhart, D; Chu, M L; Chudoba, J; Ciapetti, G; Ciftci, A K; Ciftci, R; Cinca, D; Cindro, V; Ciocca, C; Ciocio, A; Cirilli, M; Cirkovic, P; Citterio, M; Ciubancan, M; Clark, A; Clark, P J; Clarke, R N; Cleland, W; Clemens, J C; Clement, B; Clement, C; Coadou, Y; Cobal, M; Coccaro, A; Cochran, J; Coffey, L; Cogan, J G; Coggeshall, J; Cogneras, E; Colas, J; Cole, S; Colijn, A P; Collins, N J; Collins-Tooth, C; Collot, J; Colombo, T; Colon, G; Conde Muiño, P; Coniavitis, E; Conidi, M C; Consonni, S M; Consorti, V; Constantinescu, S; Conta, C; Conti, G; Conventi, F; Cooke, M; Cooper, B D; Cooper-Sarkar, A M; Copic, K; Cornelissen, T; Corradi, M; Corriveau, F; Cortes-Gonzalez, A; Cortiana, G; Costa, G; Costa, M J; Costanzo, D; Côté, D; Courneyea, L; Cowan, G; Cowden, C; Cox, B E; Cranmer, K; Crescioli, F; Cristinziani, M; Crosetti, G; Crépé-Renaudin, S; Cuciuc, C-M; Cuenca Almenar, C; Cuhadar Donszelmann, T; Curatolo, M; Curtis, C J; Cuthbert, C; Cwetanski, P; Czirr, H; Czodrowski, P; Czyczula, Z; D'Auria, S; D'Onofrio, M; D'Orazio, A; Da Cunha Sargedas De Sousa, M J; Da Via, C; Dabrowski, W; Dafinca, A; Dai, T; Dallapiccola, C; Dam, M; Dameri, M; Damiani, D S; Danielsson, H O; Dao, V; Darbo, G; Darlea, G L; Dassoulas, J A; Davey, W; Davidek, T; Davidson, N; Davidson, R; Davies, E; Davies, M; Davignon, O; Davison, A R; Davygora, Y; Dawe, E; Dawson, I; Daya-Ishmukhametova, R K; De, K; de Asmundis, R; De Castro, S; De Cecco, S; de Graat, J; De Groot, N; de Jong, P; De La Taille, C; De la Torre, H; De Lorenzi, F; de Mora, L; De Nooij, L; De Pedis, D; De Salvo, A; De Sanctis, U; De Santo, A; De Vivie De Regie, J B; De Zorzi, G; Dearnaley, W J; Debbe, R; Debenedetti, C; Dechenaux, B; Dedovich, D V; Degenhardt, J; Del Papa, C; Del Peso, J; Del Prete, T; Delemontex, T; Deliyergiyev, M; Dell'Acqua, A; Dell'Asta, L; Della Pietra, M; Della Volpe, D; Delmastro, M; Delsart, P A; Deluca, C; Demers, S; Demichev, M; Demirkoz, B; Deng, J; Denisov, S P; Derendarz, D; Derkaoui, J E; Derue, F; Dervan, P; Desch, K; Devetak, E; Deviveiros, P O; Dewhurst, A; Dewilde, B; Dhaliwal, S; Dhullipudi, R; Di Ciaccio, A; Di Ciaccio, L; Di Girolamo, A; Di Girolamo, B; Di Luise, S; Di Mattia, A; Di Micco, B; Di Nardo, R; Di Simone, A; Di Sipio, R; Diaz, M A; Diehl, E B; Dietrich, J; Dietzsch, T A; Diglio, S; Dindar Yagci, K; Dingfelder, J; Dinut, F; Dionisi, C; Dita, P; Dita, S; Dittus, F; Djama, F; Djobava, T; do Vale, M A B; Do Valle Wemans, A; Doan, T K O; Dobbs, M; Dobinson, R; Dobos, D; Dobson, E; Dodd, J; Doglioni, C; Doherty, T; Doi, Y; Dolejsi, J; Dolenc, I; Dolezal, Z; Dolgoshein, B A; Dohmae, T; Donadelli, M; Donini, J; Dopke, J; Doria, A; Dos Anjos, A; Dotti, A; Dova, M T; Doxiadis, A D; Doyle, A T; Dris, M; Dubbert, J; Dube, S; Duchovni, E; Duckeck, G; Duda, D; Dudarev, A; Dudziak, F; Dührssen, M; Duerdoth, I P; Duflot, L; Dufour, M-A; Duguid, L; Dunford, M; Duran Yildiz, H; Duxfield, R; Dwuznik, M; Dydak, F; Düren, M; Ebke, J; Eckweiler, S; Edmonds, K; Edson, W; Edwards, C A; Edwards, N C; Ehrenfeld, W; Eifert, T; Eigen, G; Einsweiler, K; Eisenhandler, E; Ekelof, T; El Kacimi, M; Ellert, M; Elles, S; Ellinghaus, F; Ellis, K; Ellis, N; Elmsheuser, J; Elsing, M; Emeliyanov, D; Engelmann, R; Engl, A; Epp, B; Erdmann, J; Ereditato, A; Eriksson, D; Ernst, J; Ernst, M; Ernwein, J; Errede, D; Errede, S; Ertel, E; Escalier, M; Esch, H; Escobar, C; Espinal Curull, X; Esposito, B; Etienne, F; Etienvre, A I; Etzion, E; Evangelakou, D; Evans, H; Fabbri, L; Fabre, C; Fakhrutdinov, R M; Falciano, S; Fang, Y; Fanti, M; Farbin, A; Farilla, A; Farley, J; Farooque, T; Farrell, S; Farrington, S M; Farthouat, P; Fassi, F; Fassnacht, P; Fassouliotis, D; Fatholahzadeh, B; Favareto, A; Fayard, L; Fazio, S; Febbraro, R; Federic, P; Fedin, O L; Fedorko, W; Fehling-Kaschek, M; Feligioni, L; Fellmann, D; Feng, C; Feng, E J; Fenyuk, A B; Ferencei, J; Fernando, W; Ferrag, S; Ferrando, J; Ferrara, V; Ferrari, A; Ferrari, P; Ferrari, R; Ferreira de Lima, D E; Ferrer, A; Ferrere, D; Ferretti, C; Ferretto Parodi, A; Fiascaris, M; Fiedler, F; Filipčič, A; Filthaut, F; Fincke-Keeler, M; Fiolhais, M C N; Fiorini, L; Firan, A; Fischer, G; Fisher, M J; Flechl, M; Fleck, I; Fleckner, J; Fleischmann, P; Fleischmann, S; Flick, T; Floderus, A; Flores Castillo, L R; Flowerdew, M J; Fonseca Martin, T; Formica, A; Forti, A; Fortin, D; Fournier, D; Fox, H; Francavilla, P; Franchini, M; Franchino, S; Francis, D; Frank, T; Franz, S; Fraternali, M; Fratina, S; French, S T; Friedrich, C; Friedrich, F; Froeschl, R; Froidevaux, D; Frost, J A; Fukunaga, C; Fullana Torregrosa, E; Fulsom, B G; Fuster, J; Gabaldon, C; Gabizon, O; Gadfort, T; Gadomski, S; Gagliardi, G; Gagnon, P; Galea, C; Gallas, E J; Gallo, V; Gallop, B J; Gallus, P; Gan, K K; Gao, Y S; Gaponenko, A; Garberson, F; Garcia-Sciveres, M; García, C; García Navarro, J E; Gardner, R W; Garelli, N; Garitaonandia, H; Garonne, V; Gatti, C; Gaudio, G; Gaur, B; Gauthier, L; Gauzzi, P; Gavrilenko, I L; Gay, C; Gaycken, G; Gazis, E N; Ge, P; Gecse, Z; Gee, C N P; Geerts, D A A; Geich-Gimbel, Ch; Gellerstedt, K; Gemme, C; Gemmell, A; Genest, M H; Gentile, S; George, M; George, S; Gerlach, P; Gershon, A; Geweniger, C; Ghazlane, H; Ghodbane, N; Giacobbe, B; Giagu, S; Giakoumopoulou, V; Giangiobbe, V; Gianotti, F; Gibbard, B; Gibson, A; Gibson, S M; Gillberg, D; Gillman, A R; Gingrich, D M; Ginzburg, J; Giokaris, N; Giordani, M P; Giordano, R; Giorgi, F M; Giovannini, P; Giraud, P F; Giugni, D; Giunta, M; Giusti, P; Gjelsten, B K; Gladilin, L K; Glasman, C; Glatzer, J; Glazov, A; Glitza, K W; Glonti, G L; Goddard, J R; Godfrey, J; Godlewski, J; Goebel, M; Göpfert, T; Goeringer, C; Gössling, C; Goldfarb, S; Golling, T; Gomes, A; Gomez Fajardo, L S; Gonçalo, R; Goncalves Pinto Firmino Da Costa, J; Gonella, L; González de la Hoz, S; Gonzalez Parra, G; Gonzalez Silva, M L; Gonzalez-Sevilla, S; Goodson, J J; Goossens, L; Gorbounov, P A; Gordon, H A; Gorelov, I; Gorfine, G; Gorini, B; Gorini, E; Gorišek, A; Gornicki, E; Gosdzik, B; Goshaw, A T; Gosselink, M; Gostkin, M I; Gough Eschrich, I; Gouighri, M; Goujdami, D; Goulette, M P; Goussiou, A G; Goy, C; Gozpinar, S; Grabowska-Bold, I; Grafström, P; Grahn, K-J; Grancagnolo, F; Grancagnolo, S; Grassi, V; Gratchev, V; Grau, N; Gray, H M; Gray, J A; Graziani, E; Grebenyuk, O G; Greenshaw, T; Greenwood, Z D; Gregersen, K; Gregor, I M; Grenier, P; Griffiths, J; Grigalashvili, N; Grillo, A A; Grinstein, S; Gris, Ph; Grishkevich, Y V; Grivaz, J-F; Gross, E; Grosse-Knetter, J; Groth-Jensen, J; Grybel, K; Guest, D; Guicheney, C; Guindon, S; Gul, U; Guler, H; Gunther, J; Guo, B; Guo, J; Gutierrez, P; Guttman, N; Gutzwiller, O; Guyot, C; Gwenlan, C; Gwilliam, C B; Haas, A; Haas, S; Haber, C; Hadavand, H K; Hadley, D R; Haefner, P; Hahn, F; Haider, S; Hajduk, Z; Hakobyan, H; Hall, D; Haller, J; Hamacher, K; Hamal, P; Hamer, M; Hamilton, A; Hamilton, S; Han, L; Hanagaki, K; Hanawa, K; Hance, M; Handel, C; Hanke, P; Hansen, J R; Hansen, J B; Hansen, J D; Hansen, P H; Hansson, P; Hara, K; Hare, G A; Harenberg, T; Harkusha, S; Harper, D; Harrington, R D; Harris, O M; Hartert, J; Hartjes, F; Haruyama, T; Harvey, A; Hasegawa, S; Hasegawa, Y; Hassani, S; Haug, S; Hauschild, M; Hauser, R; Havranek, M; Hawkes, C M; Hawkings, R J; Hawkins, A D; Hayakawa, T; Hayashi, T; Hayden, D; Hays, C P; Hayward, H S; Haywood, S J; Head, S J; Hedberg, V; Heelan, L; Heim, S; Heinemann, B; Heisterkamp, S; Helary, L; Heller, C; Heller, M; Hellman, S; Hellmich, D; Helsens, C; Henderson, R C W; Henke, M; Henrichs, A; Henriques Correia, A M; Henrot-Versille, S; Hensel, C; Henß, T; Hernandez, C M; Hernández Jiménez, Y; Herrberg, R; Herten, G; Hertenberger, R; Hervas, L; Hesketh, G G; Hessey, N P; Higón-Rodriguez, E; Hill, J C; Hiller, K H; Hillert, S; Hillier, S J; Hinchliffe, I; Hines, E; Hirose, M; Hirsch, F; Hirschbuehl, D; Hobbs, J; Hod, N; Hodgkinson, M C; Hodgson, P; Hoecker, A; Hoeferkamp, M R; Hoffman, J; Hoffmann, D; Hohlfeld, M; Holder, M; Holmgren, S O; Holy, T; Holzbauer, J L; Hong, T M; Hooft van Huysduynen, L; Horner, S; Hostachy, J-Y; Hou, S; Hoummada, A; Howard, J; Howarth, J; Hristova, I; Hrivnac, J; Hryn'ova, T; Hsu, P J; Hsu, S-C; Hu, D; Hubacek, Z; Hubaut, F; Huegging, F; Huettmann, A; Huffman, T B; Hughes, E W; Hughes, G; Huhtinen, M; Hurwitz, M; Husemann, U; Huseynov, N; Huston, J; Huth, J; Iacobucci, G; Iakovidis, G; Ibbotson, M; Ibragimov, I; Iconomidou-Fayard, L; Idarraga, J; Iengo, P; Igonkina, O; Ikegami, Y; Ikeno, M; Iliadis, D; Ilic, N; Ince, T; Inigo-Golfin, J; Ioannou, P; Iodice, M; Iordanidou, K; Ippolito, V; Irles Quiles, A; Isaksson, C; Ishino, M; Ishitsuka, M; Ishmukhametov, R; Issever, C; Istin, S; Ivashin, A V; Iwanski, W; Iwasaki, H; Izen, J M; Izzo, V; Jackson, B; Jackson, J N; Jackson, P; Jaekel, M R; Jain, V; Jakobs, K; Jakobsen, S; Jakoubek, T; Jakubek, J; Jana, D K; Jansen, E; Jansen, H; Jantsch, A; Janus, M; Jarlskog, G; Jeanty, L; Jen-La Plante, I; Jennens, D; Jenni, P; Loevschall-Jensen, A E; Jež, P; Jézéquel, S; Jha, M K; Ji, H; Ji, W; Jia, J; Jiang, Y; Jimenez Belenguer, M; Jin, S; Jinnouchi, O; Joergensen, M D; Joffe, D; Johansen, M; Johansson, K E; Johansson, P; Johnert, S; Johns, K A; Jon-And, K; Jones, G; Jones, R W L; Jones, T J; Joram, C; Jorge, P M; Joshi, K D; Jovicevic, J; Jovin, T; Ju, X; Jung, C A; Jungst, R M; Juranek, V; Jussel, P; Juste Rozas, A; Kabana, S; Kaci, M; Kaczmarska, A; Kadlecik, P; Kado, M; Kagan, H; Kagan, M; Kajomovitz, E; Kalinin, S; Kalinovskaya, L V; Kama, S; Kanaya, N; Kaneda, M; Kaneti, S; Kanno, T; Kantserov, V A; Kanzaki, J; Kaplan, B; Kapliy, A; Kaplon, J; Kar, D; Karagounis, M; Karakostas, K; Karnevskiy, M; Kartvelishvili, V; Karyukhin, A N; Kashif, L; Kasieczka, G; Kass, R D; Kastanas, A; Kataoka, M; Kataoka, Y; Katsoufis, E; Katzy, J; Kaushik, V; Kawagoe, K; Kawamoto, T; Kawamura, G; Kayl, M S; Kazama, S; Kazanin, V A; Kazarinov, M Y; Keeler, R; Kehoe, R; Keil, M; Kekelidze, G D; Keller, J S; Kenyon, M; Kepka, O; Kerschen, N; Kerševan, B P; Kersten, S; Kessoku, K; Keung, J; Khalil-Zada, F; Khandanyan, H; Khanov, A; Kharchenko, D; Khodinov, A; Khomich, A; Khoo, T J; Khoriauli, G; Khoroshilov, A; Khovanskiy, V; Khramov, E; Khubua, J; Kim, H; Kim, S H; Kimura, N; Kind, O; King, B T; King, M; King, R S B; Kirk, J; Kiryunin, A E; Kishimoto, T; Kisielewska, D; Kitamura, T; Kittelmann, T; Kiuchi, K; Kladiva, E; Klein, M; Klein, U; Kleinknecht, K; Klemetti, M; Klier, A; Klimek, P; Klimentov, A; Klingenberg, R; Klinger, J A; Klinkby, E B; Klioutchnikova, T; Klok, P F; Klous, S; Kluge, E-E; Kluge, T; Kluit, P; Kluth, S; Knecht, N S; Kneringer, E; Knoops, E B F G; Knue, A; Ko, B R; Kobayashi, T; Kobel, M; Kocian, M; Kodys, P; Köneke, K; König, A C; Koenig, S; Köpke, L; Koetsveld, F; Koevesarki, P; Koffas, T; Koffeman, E; Kogan, L A; Kohlmann, S; Kohn, F; Kohout, Z; Kohriki, T; Koi, T; Kolachev, G M; Kolanoski, H; Kolesnikov, V; Koletsou, I; Koll, J; Komar, A A; Komori, Y; Kondo, T; Kono, T; Kononov, A I; Konoplich, R; Konstantinidis, N; Koperny, S; Korcyl, K; Kordas, K; Korn, A; Korol, A; Korolkov, I; Korolkova, E V; Korotkov, V A; Kortner, O; Kortner, S; Kostyukhin, V V; Kotov, S; Kotov, V M; Kotwal, A; Kourkoumelis, C; Kouskoura, V; Koutsman, A; Kowalewski, R; Kowalski, T Z; Kozanecki, W; Kozhin, A S; Kral, V; Kramarenko, V A; Kramberger, G; Krasny, M W; Krasznahorkay, A; Kraus, J K; Kreiss, S; Krejci, F; Kretzschmar, J; Krieger, N; Krieger, P; Kroeninger, K; Kroha, H; Kroll, J; Kroseberg, J; Krstic, J; Kruchonak, U; Krüger, H; Kruker, T; Krumnack, N; Krumshteyn, Z V; Kubota, T; Kuday, S; Kuehn, S; Kugel, A; Kuhl, T; Kuhn, D; Kukhtin, V; Kulchitsky, Y; Kuleshov, S; Kummer, C; Kuna, M; Kunkle, J; Kupco, A; Kurashige, H; Kurata, M; Kurochkin, Y A; Kus, V; Kuwertz, E S; Kuze, M; Kvita, J; Kwee, R; La Rosa, A; La Rotonda, L; Labarga, L; Labbe, J; Lablak, S; Lacasta, C; Lacava, F; Lacker, H; Lacour, D; Lacuesta, V R; Ladygin, E; Lafaye, R; Laforge, B; Lagouri, T; Lai, S; Laisne, E; Lamanna, M; Lambourne, L; Lampen, C L; Lampl, W; Lancon, E; Landgraf, U; Landon, M P J; Lane, J L; Lang, V S; Lange, C; Lankford, A J; Lanni, F; Lantzsch, K; Laplace, S; Lapoire, C; Laporte, J F; Lari, T; Larner, A; Lassnig, M; Laurelli, P; Lavorini, V; Lavrijsen, W; Laycock, P; Le Dortz, O; Le Guirriec, E; Le Menedeu, E; Lecompte, T; Ledroit-Guillon, F; Lee, H; Lee, J S H; Lee, S C; Lee, L; Lefebvre, M; Legendre, M; Legger, F; Leggett, C; Lehmacher, M; Lehmann Miotto, G; Lei, X; Leite, M A L; Leitner, R; Lellouch, D; Lemmer, B; Lendermann, V; Leney, K J C; Lenz, T; Lenzen, G; Lenzi, B; Leonhardt, K; Leontsinis, S; Lepold, F; Leroy, C; Lessard, J-R; Lester, C G; Lester, C M; Levêque, J; Levin, D; Levinson, L J; Lewis, A; Lewis, G H; Leyko, A M; Leyton, M; Li, B; Li, H; Li, S; Li, X; Liang, Z; Liao, H; Liberti, B; Lichard, P; Lichtnecker, M; Lie, K; Liebig, W; Limbach, C; Limosani, A; Limper, M; Lin, S C; Linde, F; Linnemann, J T; Lipeles, E; Lipniacka, A; Liss, T M; Lissauer, D; Lister, A; Litke, A M; Liu, C; Liu, D; Liu, H; Liu, J B; Liu, L; Liu, M; Liu, Y; Livan, M; Livermore, S S A; Lleres, A; Llorente Merino, J; Lloyd, S L; Lobodzinska, E; Loch, P; Lockman, W S; Loddenkoetter, T; Loebinger, F K; Loginov, A; Loh, C W; Lohse, T; Lohwasser, K; Lokajicek, M; Lombardo, V P; Long, R E; Lopes, L; Lopez Mateos, D; Lorenz, J; Lorenzo Martinez, N; Losada, M; Loscutoff, P; Lo Sterzo, F; Losty, M J; Lou, X; Lounis, A; Loureiro, K F; Love, J; Love, P A; Lowe, A J; Lu, F; Lubatti, H J; Luci, C; Lucotte, A; Ludwig, A; Ludwig, D; Ludwig, I; Ludwig, J; Luehring, F; Luijckx, G; Lukas, W; Lumb, D; Luminari, L; Lund, E; Lund-Jensen, B; Lundberg, B; Lundberg, J; Lundberg, O; Lundquist, J; Lungwitz, M; Lynn, D; Lytken, E; Ma, H; Ma, L L; Maccarrone, G; Macchiolo, A; Maček, B; Machado Miguens, J; Mackeprang, R; Madaras, R J; Maddocks, H J; Mader, W F; Maenner, R; Maeno, T; Mättig, P; Mättig, S; Magnoni, L; Magradze, E; Mahboubi, K; Mahmoud, S; Mahout, G; Maiani, C; Maidantchik, C; Maio, A; Majewski, S; Makida, Y; Makovec, N; Mal, P; Malaescu, B; Malecki, Pa; Malecki, P; Maleev, V P; Malek, F; Mallik, U; Malon, D; Malone, C; Maltezos, S; Malyshev, V; Malyukov, S; Mameghani, R; Mamuzic, J; Manabe, A; Mandelli, L; Mandić, I; Mandrysch, R; Maneira, J; Manfredini, A; Mangeard, P S; Manhaes de Andrade Filho, L; Manjarres Ramos, J A; Mann, A; Manning, P M; Manousakis-Katsikakis, A; Mansoulie, B; Mapelli, A; Mapelli, L; March, L; Marchand, J F; Marchese, F; Marchiori, G; Marcisovsky, M; Marino, C P; Marroquim, F; Marshall, Z; Martens, F K; Marti, L F; Marti-Garcia, S; Martin, B; Martin, B; Martin, J P; Martin, T A; Martin, V J; Martin Dit Latour, B; Martin-Haugh, S; Martinez, M; Martinez Outschoorn, V; Martyniuk, A C; Marx, M; Marzano, F; Marzin, A; Masetti, L; Mashimo, T; Mashinistov, R; Masik, J; Maslennikov, A L; Massa, I; Massaro, G; Massol, N; Mastrandrea, P; Mastroberardino, A; Masubuchi, T; Matricon, P; Matsunaga, H; Matsushita, T; Mattravers, C; Maurer, J; Maxfield, S J; Mayne, A; Mazini, R; Mazur, M; Mazzaferro, L; Mazzanti, M; Mc Donald, J; Mc Kee, S P; McCarn, A; McCarthy, R L; McCarthy, T G; McCubbin, N A; McFarlane, K W; McFayden, J A; McHedlidze, G; McLaughlan, T; McMahon, S J; McPherson, R A; Meade, A; Mechnich, J; Mechtel, M; Medinnis, M; Meera-Lebbai, R; Meguro, T; Mehdiyev, R; Mehlhase, S; Mehta, A; Meier, K; Meirose, B; Melachrinos, C; Mellado Garcia, B R; Meloni, F; Mendoza Navas, L; Meng, Z; Mengarelli, A; Menke, S; Meoni, E; Mercurio, K M; Mermod, P; Merola, L; Meroni, C; Merritt, F S; Merritt, H; Messina, A; Metcalfe, J; Mete, A S; Meyer, C; Meyer, C; Meyer, J-P; Meyer, J; Meyer, J; Meyer, T C; Miao, J; Michal, S; Micu, L; Middleton, R P; Migas, S; Mijović, L; Mikenberg, G; Mikestikova, M; Mikuž, M; Miller, D W; Miller, R J; Mills, W J; Mills, C; Milov, A; Milstead, D A; Milstein, D; Minaenko, A A; Miñano Moya, M; Minashvili, I A; Mincer, A I; Mindur, B; Mineev, M; Ming, Y; Mir, L M; Mirabelli, G; Mitrevski, J; Mitsou, V A; Mitsui, S; Miyagawa, P S; Mjörnmark, J U; Moa, T; Moeller, V; Mönig, K; Möser, N; Mohapatra, S; Mohr, W; Moles-Valls, R; Monk, J; Monnier, E; Montejo Berlingen, J; Monticelli, F; Monzani, S; Moore, R W; Moorhead, G F; Mora Herrera, C; Moraes, A; Morange, N; Morel, J; Morello, G; Moreno, D; Moreno Llácer, M; Morettini, P; Morgenstern, M; Morii, M; Morley, A K; Mornacchi, G; Morris, J D; Morvaj, L; Moser, H G; Mosidze, M; Moss, J; Mount, R; Mountricha, E; Mouraviev, S V; Moyse, E J W; Mueller, F; Mueller, J; Mueller, K; Müller, T A; Mueller, T; Muenstermann, D; Munwes, Y; Murray, W J; Mussche, I; Musto, E; Myagkov, A G; Myska, M; Nadal, J; Nagai, K; Nagai, R; Nagano, K; Nagarkar, A; Nagasaka, Y; Nagel, M; Nairz, A M; Nakahama, Y; Nakamura, K; Nakamura, T; Nakano, I; Nanava, G; Napier, A; Narayan, R; Nash, M; Nattermann, T; Naumann, T; Navarro, G; Neal, H A; Nechaeva, P Yu; Neep, T J; Negri, A; Negri, G; Negrini, M; Nektarijevic, S; Nelson, A; Nelson, T K; Nemecek, S; Nemethy, P; Nepomuceno, A A; Nessi, M; Neubauer, M S; Neumann, M; Neusiedl, A; Neves, R M; Nevski, P; Newman, P R; Nguyen Thi Hong, V; Nickerson, R B; Nicolaidou, R; Nicquevert, B; Niedercorn, F; Nielsen, J; Nikiforou, N; Nikiforov, A; Nikolaenko, V; Nikolic-Audit, I; Nikolics, K; Nikolopoulos, K; Nilsen, H; Nilsson, P; Ninomiya, Y; Nisati, A; Nisius, R; Nobe, T; Nodulman, L; Nomachi, M; Nomidis, I; Norberg, S; Nordberg, M; Norton, P R; Novakova, J; Nozaki, M; Nozka, L; Nugent, I M; Nuncio-Quiroz, A-E; Nunes Hanninger, G; Nunnemann, T; Nurse, E; O'Brien, B J; O'Neil, D C; O'Shea, V; Oakes, L B; Oakham, F G; Oberlack, H; Ocariz, J; Ochi, A; Oda, S; Odaka, S; Odier, J; Ogren, H; Oh, A; Oh, S H; Ohm, C C; Ohshima, T; Okawa, H; Okumura, Y; Okuyama, T; Olariu, A; Olchevski, A G; Olivares Pino, S A; Oliveira, M; Oliveira Damazio, D; Oliver Garcia, E; Olivito, D; Olszewski, A; Olszowska, J; Onofre, A; Onyisi, P U E; Oram, C J; Oreglia, M J; Oren, Y; Orestano, D; Orlando, N; Orlov, I; Oropeza Barrera, C; Orr, R S; Osculati, B; Ospanov, R; Osuna, C; Otero Y Garzon, G; Ottersbach, J P; Ouchrif, M; Ouellette, E A; Ould-Saada, F; Ouraou, A; Ouyang, Q; Ovcharova, A; Owen, M; Owen, S; Ozcan, V E; Ozturk, N; Pacheco Pages, A; Padilla Aranda, C; Pagan Griso, S; Paganis, E; Pahl, C; Paige, F; Pais, P; Pajchel, K; Palacino, G; Paleari, C P; Palestini, S; Pallin, D; Palma, A; Palmer, J D; Pan, Y B; Panagiotopoulou, E; Pani, P; Panikashvili, N; Panitkin, S; Pantea, D; Papadelis, A; Papadopoulou, Th D; Paramonov, A; Paredes Hernandez, D; Park, W; Parker, M A; Parodi, F; Parsons, J A; Parzefall, U; Pashapour, S; Pasqualucci, E; Passaggio, S; Passeri, A; Pastore, F; Pastore, Fr; Pásztor, G; Pataraia, S; Patel, N; Pater, J R; Patricelli, S; Pauly, T; Pecsy, M; Pedraza Lopez, S; Pedraza Morales, M I; Peleganchuk, S V; Pelikan, D; Peng, H; Penning, B; Penson, A; Penwell, J; Perantoni, M; Perez, K; Perez Cavalcanti, T; Perez Codina, E; Pérez García-Estañ, M T; Perez Reale, V; Perini, L; Pernegger, H; Perrino, R; Perrodo, P; Peshekhonov, V D; Peters, K; Petersen, B A; Petersen, J; Petersen, T C; Petit, E; Petridis, A; Petridou, C; Petrolo, E; Petrucci, F; Petschull, D; Petteni, M; Pezoa, R; Phan, A; Phillips, P W; Piacquadio, G; Picazio, A; Piccaro, E; Piccinini, M; Piec, S M; Piegaia, R; Pignotti, D T; Pilcher, J E; Pilkington, A D; Pina, J; Pinamonti, M; Pinder, A; Pinfold, J L; Pinto, B; Pizio, C; Plamondon, M; Pleier, M-A; Plotnikova, E; Poblaguev, A; Poddar, S; Podlyski, F; Poggioli, L; Pohl, D; Pohl, M; Polesello, G; Policicchio, A; Polini, A; Poll, J; Polychronakos, V; Pomeroy, D; Pommès, K; Pontecorvo, L; Pope, B G; Popeneciu, G A; Popovic, D S; Poppleton, A; Portell Bueso, X; Pospelov, G E; Pospisil, S; Potrap, I N; Potter, C J; Potter, C T; Poulard, G; Poveda, J; Pozdnyakov, V; Prabhu, R; Pralavorio, P; Pranko, A; Prasad, S; Pravahan, R; Prell, S; Pretzl, K; Price, D; Price, J; Price, L E; Prieur, D; Primavera, M; Prokofiev, K; Prokoshin, F; Protopopescu, S; Proudfoot, J; Prudent, X; Przybycien, M; Przysiezniak, H; Psoroulas, S; Ptacek, E; Pueschel, E; Purdham, J; Purohit, M; Puzo, P; Pylypchenko, Y; Qian, J; Quadt, A; Quarrie, D R; Quayle, W B; Quinonez, F; Raas, M; Radescu, V; Radloff, P; Rador, T; Ragusa, F; Rahal, G; Rahimi, A M; Rahm, D; Rajagopalan, S; Rammensee, M; Rammes, M; Randle-Conde, A S; Randrianarivony, K; Rauscher, F; Rave, T C; Raymond, M; Read, A L; Rebuzzi, D M; Redelbach, A; Redlinger, G; Reece, R; Reeves, K; Reinherz-Aronis, E; Reinsch, A; Reisinger, I; Rembser, C; Ren, Z L; Renaud, A; Rescigno, M; Resconi, S; Resende, B; Reznicek, P; Rezvani, R; Richter, R; Richter-Was, E; Ridel, M; Rijpstra, M; Rijssenbeek, M; Rimoldi, A; Rinaldi, L; Rios, R R; Riu, I; Rivoltella, G; Rizatdinova, F; Rizvi, E; Robertson, S H; Robichaud-Veronneau, A; Robinson, D; Robinson, J E M; Robson, A; Rocha de Lima, J G; Roda, C; Roda Dos Santos, D; Roe, A; Roe, S; Røhne, O; Rolli, S; Romaniouk, A; Romano, M; Romeo, G; Romero Adam, E; Rompotis, N; Roos, L; Ros, E; Rosati, S; Rosbach, K; Rose, A; Rose, M; Rosenbaum, G A; Rosenberg, E I; Rosendahl, P L; Rosenthal, O; Rosselet, L; Rossetti, V; Rossi, E; Rossi, L P; Rotaru, M; Roth, I; Rothberg, J; Rousseau, D; Royon, C R; Rozanov, A; Rozen, Y; Ruan, X; Rubbo, F; Rubinskiy, I; Ruckstuhl, N; Rud, V I; Rudolph, C; Rudolph, G; Rühr, F; Ruiz-Martinez, A; Rumyantsev, L; Rurikova, Z; Rusakovich, N A; Rutherfoord, J P; Ruwiedel, C; Ruzicka, P; Ryabov, Y F; Rybar, M; Rybkin, G; Ryder, N C; Saavedra, A F; Sadeh, I; Sadrozinski, H F-W; Sadykov, R; Safai Tehrani, F; Sakamoto, H; Salamanna, G; Salamon, A; Saleem, M; Salek, D; Salihagic, D; Salnikov, A; Salt, J; Salvachua Ferrando, B M; Salvatore, D; Salvatore, F; Salvucci, A; Salzburger, A; Sampsonidis, D; Samset, B H; Sanchez, A; Sanchez Martinez, V; Sandaker, H; Sander, H G; Sanders, M P; Sandhoff, M; Sandoval, T; Sandoval, C; Sandstroem, R; Sankey, D P C; Sansoni, A; Santamarina Rios, C; Santoni, C; Santonico, R; Santos, H; Saraiva, J G; Sarangi, T; Sarkisyan-Grinbaum, E; Sarri, F; Sartisohn, G; Sasaki, O; Sasaki, Y; Sasao, N; Satsounkevitch, I; Sauvage, G; Sauvan, E; Sauvan, J B; Savard, P; Savinov, V; Savu, D O; Sawyer, L; Saxon, D H; Saxon, J; Sbarra, C; Sbrizzi, A; Scannicchio, D A; Scarcella, M; Schaarschmidt, J; Schacht, P; Schaefer, D; Schäfer, U; Schaepe, S; Schaetzel, S; Schaffer, A C; Schaile, D; Schamberger, R D; Schamov, A G; Scharf, V; Schegelsky, V A; Scheirich, D; Schernau, M; Scherzer, M I; Schiavi, C; Schieck, J; Schioppa, M; Schlenker, S; Schmidt, E; Schmieden, K; Schmitt, C; Schmitt, S; Schmitz, M; Schneider, B; Schnoor, U; Schoening, A; Schorlemmer, A L S; Schott, M; Schouten, D; Schovancova, J; Schram, M; Schroeder, C; Schroer, N; Schultens, M J; Schultes, J; Schultz-Coulon, H-C; Schulz, H; Schumacher, M; Schumm, B A; Schune, Ph; Schwanenberger, C; Schwartzman, A; Schwegler, Ph; Schwemling, Ph; Schwienhorst, R; Schwierz, R; Schwindling, J; Schwindt, T; Schwoerer, M; Sciolla, G; Scott, W G; Searcy, J; Sedov, G; Sedykh, E; Seidel, S C; Seiden, A; Seifert, F; Seixas, J M; Sekhniaidze, G; Sekula, S J; Selbach, K E; Seliverstov, D M; Sellden, B; Sellers, G; Seman, M; Semprini-Cesari, N; Serfon, C; Serin, L; Serkin, L; Seuster, R; Severini, H; Sfyrla, A; Shabalina, E; Shamim, M; Shan, L Y; Shank, J T; Shao, Q T; Shapiro, M; Shatalov, P B; Shaw, K; Sherman, D; Sherwood, P; Shibata, A; Shimizu, S; Shimojima, M; Shin, T; Shiyakova, M; Shmeleva, A; Shochet, M J; Short, D; Shrestha, S; Shulga, E; Shupe, M A; Sicho, P; Sidoti, A; Siegert, F; Sijacki, Dj; Silbert, O; Silva, J; Silver, Y; Silverstein, D; Silverstein, S B; Simak, V; Simard, O; Simic, Lj; Simion, S; Simioni, E; Simmons, B; Simoniello, R; Simonyan, M; Sinervo, P; Sinev, N B; Sipica, V; Siragusa, G; Sircar, A; Sisakyan, A N; Sivoklokov, S Yu; Sjölin, J; Sjursen, T B; Skinnari, L A; Skottowe, H P; Skovpen, K; Skubic, P; Slater, M; Slavicek, T; Sliwa, K; Smakhtin, V; Smart, B H; Smestad, S L; Smirnov, S Yu; Smirnov, Y; Smirnova, L N; Smirnova, O; Smith, B C; Smith, D; Smith, K M; Smizanska, M; Smolek, K; Snesarev, A A; Snow, S W; Snow, J; Snyder, S; Sobie, R; Sodomka, J; Soffer, A; Solans, C A; Solar, M; Solc, J; Soldatov, E Yu; Soldevila, U; Solfaroli Camillocci, E; Solodkov, A A; Solovyanov, O V; Solovyev, V; Soni, N; Sopko, V; Sopko, B; Sosebee, M; Soualah, R; Soukharev, A; Spagnolo, S; Spanò, F; Spighi, R; Spigo, G; Spiwoks, R; Spousta, M; Spreitzer, T; Spurlock, B; St Denis, R D; Stahlman, J; Stamen, R; Stanecka, E; Stanek, R W; Stanescu, C; Stanescu-Bellu, M; Stanitzki, M M; Stapnes, S; Starchenko, E A; Stark, J; Staroba, P; Starovoitov, P; Staszewski, R; Staude, A; Stavina, P; Steele, G; Steinbach, P; Steinberg, P; Stekl, I; Stelzer, B; Stelzer, H J; Stelzer-Chilton, O; Stenzel, H; Stern, S; Stewart, G A; Stillings, J A; Stockton, M C; Stoerig, K; Stoicea, G; Stonjek, S; Strachota, P; Stradling, A R; Straessner, A; Strandberg, J; Strandberg, S; Strandlie, A; Strang, M; Strauss, E; Strauss, M; Strizenec, P; Ströhmer, R; Strom, D M; Strong, J A; Stroynowski, R; Strube, J; Stugu, B; Stumer, I; Stupak, J; Sturm, P; Styles, N A; Soh, D A; Su, D; Subramania, Hs; Succurro, A; Sugaya, Y; Suhr, C; Suk, M; Sulin, V V; Sultansoy, S; Sumida, T; Sun, X; Sundermann, J E; Suruliz, K; Susinno, G; Sutton, M R; Suzuki, Y; Suzuki, Y; Svatos, M; Swedish, S; Sykora, I; Sykora, T; Sánchez, J; Ta, D; Tackmann, K; Taffard, A; Tafirout, R; Taiblum, N; Takahashi, Y; Takai, H; Takashima, R; Takeda, H; Takeshita, T; Takubo, Y; Talby, M; Talyshev, A; Tamsett, M C; Tanaka, J; Tanaka, R; Tanaka, S; Tanaka, S; Tanasijczuk, A J; Tani, K; Tannoury, N; Tapprogge, S; Tardif, D; Tarem, S; Tarrade, F; Tartarelli, G F; Tas, P; Tasevsky, M; Tassi, E; Tatarkhanov, M; Tayalati, Y; Taylor, C; Taylor, F E; Taylor, G N; Taylor, W; Teinturier, M; Teischinger, F A; Teixeira Dias Castanheira, M; Teixeira-Dias, P; Temming, K K; Ten Kate, H; Teng, P K; Terada, S; Terashi, K; Terron, J; Testa, M; Teuscher, R J; Therhaag, J; Theveneaux-Pelzer, T; Thoma, S; Thomas, J P; Thompson, E N; Thompson, P D; Thompson, P D; Thompson, A S; Thomsen, L A; Thomson, E; Thomson, M; Thong, W M; Thun, R P; Tian, F; Tibbetts, M J; Tic, T; Tikhomirov, V O; Tikhonov, Y A; Timoshenko, S; Tipton, P; Tisserant, S; Todorov, T; Todorova-Nova, S; Toggerson, B; Tojo, J; Tokár, S; Tokushuku, K; Tollefson, K; Tomoto, M; Tompkins, L; Toms, K; Tonoyan, A; Topfel, C; Topilin, N D; Torchiani, I; Torrence, E; Torres, H; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Trefzger, T; Tremblet, L; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Tripiana, M F; Triplett, N; Trischuk, W; Trocmé, B; Troncon, C; Trottier-McDonald, M; Trzebinski, M; Trzupek, A; Tsarouchas, C; Tseng, J C-L; Tsiakiris, M; Tsiareshka, P V; Tsionou, D; Tsipolitis, G; Tsiskaridze, S; Tsiskaridze, V; Tskhadadze, E G; Tsukerman, I I; Tsulaia, V; Tsung, J-W; Tsuno, S; Tsybychev, D; Tua, A; Tudorache, A; Tudorache, V; Tuggle, J M; Turala, M; Turecek, D; Turk Cakir, I; Turlay, E; Turra, R; Tuts, P M; Tykhonov, A; Tylmad, M; Tyndel, M; Tzanakos, G; Uchida, K; Ueda, I; Ueno, R; Ugland, M; Uhlenbrock, M; Uhrmacher, M; Ukegawa, F; Unal, G; Undrus, A; Unel, G; Unno, Y; Urbaniec, D; Urquijo, P; Usai, G; Uslenghi, M; Vacavant, L; Vacek, V; Vachon, B; Vahsen, S; Valenta, J; Valentinetti, S; Valero, A; Valkar, S; Valladolid Gallego, E; Vallecorsa, S; Valls Ferrer, J A; Van Der Deijl, P C; van der Geer, R; van der Graaf, H; Van Der Leeuw, R; van der Poel, E; van der Ster, D; van Eldik, N; van Gemmeren, P; van Vulpen, I; Vanadia, M; Vandelli, W; Vaniachine, A; Vankov, P; Vannucci, F; Vari, R; Varol, T; Varouchas, D; Vartapetian, A; Varvell, K E; Vassilakopoulos, V I; Vazeille, F; Vazquez Schroeder, T; Vegni, G; Veillet, J J; Veloso, F; Veness, R; Veneziano, S; Ventura, A; Ventura, D; Venturi, M; Venturi, N; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, J C; Vest, A; Vetterli, M C; Vichou, I; Vickey, T; Vickey Boeriu, O E; Viehhauser, G H A; Viel, S; Villa, M; Villaplana Perez, M; Vilucchi, E; Vincter, M G; Vinek, E; Vinogradov, V B; Virchaux, M; Virzi, J; Vitells, O; Viti, M; Vivarelli, I; Vives Vaque, F; Vlachos, S; Vladoiu, D; Vlasak, M; Vogel, A; Vokac, P; Volpi, G; Volpi, M; Volpini, G; von der Schmitt, H; von Radziewski, H; von Toerne, E; Vorobel, V; Vorwerk, V; Vos, M; Voss, R; Voss, T T; Vossebeld, J H; Vranjes, N; Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vu Anh, T; Vuillermet, R; Vukotic, I; Wagner, W; Wagner, P; Wahlen, H; Wahrmund, S; Wakabayashi, J; Walch, S; Walder, J; Walker, R; Walkowiak, W; Wall, R; Waller, P; Walsh, B; Wang, C; Wang, H; Wang, H; Wang, J; Wang, J; Wang, R; Wang, S M; Wang, T; Warburton, A; Ward, C P; Warsinsky, M; Washbrook, A; Wasicki, C; Watanabe, I; Watkins, P M; Watson, A T; Watson, I J; Watson, M F; Watts, G; Watts, S; Waugh, A T; Waugh, B M; Weber, M S; Weber, P; Weidberg, A R; Weigell, P; Weingarten, J; Weiser, C; Wells, P S; Wenaus, T; Wendland, D; Weng, Z; Wengler, T; Wenig, S; Wermes, N; Werner, M; Werner, P; Werth, M; Wessels, M; Wetter, J; Weydert, C; Whalen, K; Wheeler-Ellis, S J; White, A; White, M J; White, S; Whitehead, S R; Whiteson, D; Whittington, D; Wicek, F; Wicke, D; Wickens, F J; Wiedenmann, W; Wielers, M; Wienemann, P; Wiglesworth, C; Wiik-Fuchs, L A M; Wijeratne, P A; Wildauer, A; Wildt, M A; Wilhelm, I; Wilkens, H G; Will, J Z; Williams, E; Williams, H H; Willis, W; Willocq, S; Wilson, J A; Wilson, M G; Wilson, A; Wingerter-Seez, I; Winkelmann, S; Winklmeier, F; Wittgen, M; Wollstadt, S J; Wolter, M W; Wolters, H; Wong, W C; Wooden, G; Wosiek, B K; Wotschack, J; Woudstra, M J; Wozniak, K W; Wraight, K; Wright, M; Wrona, B; Wu, S L; Wu, X; Wu, Y; Wulf, E; Wynne, B M; Xella, S; Xiao, M; Xie, S; Xu, C; Xu, D; Yabsley, B; Yacoob, S; Yamada, M; Yamaguchi, H; Yamamoto, A; Yamamoto, K; Yamamoto, S; Yamamura, T; Yamanaka, T; Yamaoka, J; Yamazaki, T; Yamazaki, Y; Yan, Z; Yang, H; Yang, U K; Yang, Y; Yang, Z; Yanush, S; Yao, L; Yao, Y; Yasu, Y; Ybeles Smit, G V; Ye, J; Ye, S; Yilmaz, M; Yoosoofmiya, R; Yorita, K; Yoshida, R; Young, C; Young, C J; Youssef, S; Yu, D; Yu, J; Yu, J; Yuan, L; Yurkewicz, A; Byszewski, M; Zabinski, B; Zaidan, R; Zaitsev, A M; Zajacova, Z; Zanello, L; Zanzi, D; Zaytsev, A; Zeitnitz, C; Zeman, M; Zemla, A; Zendler, C; Zenin, O; Zeniš, T; Zinonos, Z; Zenz, S; Zerwas, D; Zevi Della Porta, G; Zhan, Z; Zhang, D; Zhang, H; Zhang, J; Zhang, X; Zhang, Z; Zhao, L; Zhao, T; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, N; Zhou, Y; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhuravlov, V; Zieminska, D; Zimin, N I; Zimmermann, R; Zimmermann, S; Zimmermann, S; Ziolkowski, M; Zitoun, R; Zivković, L; Zmouchko, V V; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zutshi, V; Zwalinski, L

2012-11-21

A search is presented for direct top squark pair production in final states with one isolated electron or muon, jets, and missing transverse momentum in proton-proton collisions at sqrt[s] = 7 TeV. The measurement is based on 4.7 fb(-1) of data collected with the ATLAS detector at the LHC. Each top squark is assumed to decay to a top quark and the lightest supersymmetric particle (LSP). The data are found to be consistent with standard model expectations. Top squark masses between 230 GeV and 440 GeV are excluded with 95% confidence for massless LSPs, and top squark masses around 400 GeV are excluded for LSP masses up to 125 GeV.

Characteristics of hardron-nucleus interactions at 100 GeV/c

NASA Astrophysics Data System (ADS)

Toothacker, W. S.; Whitmore, J.; Elcombe, P. A.; Hill, J. C.; Neale, W. W.; Kowald, W.; Walker, W. D.; Lucas, P.; Voyvodic, L.; Ammar, R.; Coppage, D.; Davis, R.; Gress, J.; Kanekal, S.; Kwak, N.; Bishop, J. M.; Biswas, N. N.; Cason, N. M.; Kenney, V. P.; Mattingly, M. C. K.; Ruchti, R. C.; Shepard, W. D.; Ting, S. J. Y.

1988-11-01

We report on 100 GeV/c interactions of p and p¯ with Ag and Au targets. This is a subset of the data from Fermilab experiment E597 and was performed with the 30-inch bubble chamber and Downstream Particle Identifier. Final state protons with laboratory momentum less than 1.4 GeV/c have been identified by their ionization in the bubble chamber. Final state protons/antiprotons with laboratory momentum greater than 10 GeV/c have been identified using CRISIS, an ionization sampling drift chamber. The cross section and mean transverse momentum squared of the leading baryon from the reactions p+(Ag,Au)→p+X and p¯+(Ag,Au)→p¯+X are presented as a function of the rapidity loss of the leading baryon. The laboratory rapidity and transverse momentum squared of the associated pions are also presented.

Magnetic characteristics and nanostructures of FePt granular films with GeO2 segregant

NASA Astrophysics Data System (ADS)

Ono, Takuya; Moriya, Tomohiro; Hatayama, Masatoshi; Tsumura, Kaoru; Kikuchi, Nobuaki; Okamoto, Satoshi; Kitakami, Osamu; Shimatsu, Takehito

2017-01-01

To realize a granular film composed of L10-FePt grains with high uniaxial magnetic anisotropy energy, Ku, and segregants for energy-assisted magnetic recording, a FePt-GeO2/FePt-C stacked film was investigated in the engineering process. The FePt-GeO2/FePt-C stacked film fabricated at a substrate temperature of 450 °C realized uniaxial magnetic anisotropy, Kugrain , of about 2.5 × 107 erg/cm3, which is normalized by the volume fraction of FePt grains, and a granular structure with an averaged grain size of 7.7 nm. As the thickness of the FePt-GeO2 upper layer was increased to 9 nm, the Ku values were almost constant. That result differs absolutely from the thickness dependences of the other oxide segregant materials such as SiO2 and TiO2. Such differences on the oxide segregant are attributed to their chemical bond. The strong covalent bond of GeO2 is expected to result in high Ku of the FePt-GeO2/FePt-C stacked films.

Cobalt germanide nanostructure formation and memory characteristic enhancement in silicon oxide films

NASA Astrophysics Data System (ADS)

Joo, Beom Soo; Kim, Hyunseung; Jang, Seunghun; Han, Dongwoo; Han, Moonsup

2018-08-01

We investigated nano-floating gate memory having a charge trap layer (CTL) composed of cobalt germanide nanostructure (ns-CoGe). A tunneling oxide layer; a CTL containing Co, Ge, and Si; and a blocking oxide layer were sequentially deposited on a p-type silicon substrate by RF magnetron sputtering and low-pressure chemical vapor deposition. We optimized the CTL formation conditions by rapid thermal annealing at a somewhat low temperature (about 830 °C) by considering the differences in Gibbs free energy and chemical enthalpy among the components. To characterize the charge storage properties, capacitance-voltage (C-V) measurements were performed. Further, we used X-ray photoelectron spectroscopy for chemical analysis of the CTL. In this work, we not only report that the C-V measurement shows a remarkable opening of the memory window for the ns-CoGe compared with those of nanostructures composed of Co or Ge alone, but also clarify that the improvement in the memory characteristics originates in the nanostructure formation, which consists mainly of Co-Ge bonds. We expect ns-CoGe to be a strong candidate for fabrication of next-generation memory devices.

Al{sub 2}O{sub 3}/GeO{sub x} gate stack on germanium substrate fabricated by in situ cycling ozone oxidation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xu; Zeng, Zhen-Hua; Microwave Device and IC Department, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029

2014-09-01

Al{sub 2}O{sub 3}/GeO{sub x}/Ge gate stack fabricated by an in situ cycling ozone oxidation (COO) method in the atomic layer deposition (ALD) system at low temperature is systematically investigated. Excellent electrical characteristics such as minimum interface trap density as low as 1.9 × 10{sup 11 }cm{sup −2 }eV{sup −1} have been obtained by COO treatment. The impact of COO treatment against the band alignment of Al{sub 2}O{sub 3} with respect to Ge is studied by x-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE). Based on both XPS and SE studies, the origin of gate leakage in the ALD-Al{sub 2}O{sub 3} is attributed to themore » sub-gap states, which may be correlated to the OH-related groups in Al{sub 2}O{sub 3} network. It is demonstrated that the COO method is effective in repairing the OH-related defects in high-k dielectrics as well as forming superior high-k/Ge interface for high performance Ge MOS devices.« less

Electrically pumped 1.3 microm room-temperature InAs/GaAs quantum dot lasers on Si substrates by metal-mediated wafer bonding and layer transfer.

PubMed

Tanabe, Katsuaki; Guimard, Denis; Bordel, Damien; Iwamoto, Satoshi; Arakawa, Yasuhiko

2010-05-10

An electrically pumped InAs/GaAs quantum dot laser on a Si substrate has been demonstrated. The double-hetero laser structure was grown on a GaAs substrate by metal-organic chemical vapor deposition and layer-transferred onto a Si substrate by GaAs/Si wafer bonding mediated by a 380-nm-thick Au-Ge-Ni alloy layer. This broad-area Fabry-Perot laser exhibits InAs quantum dot ground state lasing at 1.31 microm at room temperature with a threshold current density of 600 A/cm(2). (c) 2010 Optical Society of America.

Disordered Phase of the 3x3 Pb/Ge(111) structure at low temperature

NASA Astrophysics Data System (ADS)

Guo, Jiandong; Bolorizadeh, Mehdi; Plummer, E. W.

2003-03-01

* Dept. of Phys., Univ. of Tenn., Knoxville, TN 37996. ** Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831. At a metal surface or a thin metallic film on a semiconductor there is a competition between the long-range adatom-adatom interactions and the local stress fields imposed by the substrate bulk structure. In interesting cases this leads to a structural phase transition. In this talk we present a STM investigation of the two-dimensional structure at different temperatures for the 1/3 monolayer of Pb on Ge(111) system. When the temperature is lowered the interface undergoes a (3x3)R30^o to (3x3) phase transition at roughly 110 K. Substitutional Ge defects play a crucial role in the phase transition as has been reported for the isoelectronic Sn/Ge system. However, unlike Sn/Ge, as the temperature is lowed below 80 K the (3x3) structure in Pb/Ge is broken and a disordered glassy-like structure is observed. This is very similar to the glassy phase predicted by Shi et al. in a model calculation for the Sn/Ge system. The question we address is, is this disordered low temperature phase inherent to the ideal Pb/Ge system or a consequence of the Ge substitutional defects? This work was funded by NSF DMR-0105232 and Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725.

Enhancing crystalline silicon solar cell efficiency with SixGe1-x layers

NASA Astrophysics Data System (ADS)

Ali, Adnan; Cheow, S. L.; Azhari, A. W.; Sopian, K.; Zaidi, Saleem H.

Crystalline silicon (c-Si) solar cell represents a cost effective, environment-friendly, and proven renewable energy resource. Industrially manufacturing of c-Si solar has now matured in terms of efficiency and cost. Continuing cost-effective efficiency enhancement requires transition towards thinner wafers in near term and thin-films in the long term. Successful implementation of either of these alternatives must address intrinsic optical absorption limitation of Si. Bandgap engineering through integration with SixGe1-x layers offers an attractive, inexpensive option. With the help of PC1D software, role of SixGe1-x layers in conventional c-Si solar cells has been intensively investigated in both wafer and thin film configurations by varying Ge concentration, thickness, and placement. In wafer configuration, increase in Ge concentration leads to enhanced absorption through bandgap broadening with an efficiency enhancement of 8% for Ge concentrations of less than 20%. At higher Ge concentrations, despite enhanced optical absorption, efficiency is reduced due to substantial lowering of open-circuit voltage. In 5-25-μm thickness, thin-film solar cell configurations, efficiency gain in excess of 30% is achievable. Therefore, SixGe1-x based thin-film solar cells with an order of magnitude reduction in costly Si material are ideally-suited both in terms of high efficiency and cost. Recent research has demonstrated significant improvement in epitaxially grown SixGe1-x layers on nanostructured Si substrates, thereby enhancing potential of this approach for next generation of c-Si based photovoltaics.

Growth and phase transformations of Ir on Ge(111)

NASA Astrophysics Data System (ADS)

Mullet, C. H.; Stenger, B. H.; Durand, A. M.; Morad, J. A.; Sato, Y.; Poppenheimer, E. C.; Chiang, S.

2017-12-01

The growth of Ir on Ge(111) as a function of temperature between 23 °C and 820 °C is characterized with low energy electron microscopy (LEEM), low energy electron diffraction (LEED), scanning tunneling microscopy (STM), and x-ray photoemission spectroscopy (XPS). Deposition onto a substrate at 350 °C revealed a novel growth mode consisting of multilayer Ir islands with (√3 × √3)R30° (abbreviated as √3) structure interconnected by ;bridges; of single-layer Ir several atoms wide. For deposition onto substrates above 500 °C, the √3 Ir phase grows with dendritic morphology, and substrate step bunches act as barriers to √3 Ir growth. LEEM images showed Stranski-Krastanov growth for 650-820 °C: after the √3 phase covers the surface, corresponding to 2 monolayers (ML) Ir coverage, multilayer hexagonal-shaped Ir islands form, surrounded by regions of IrGe alloy. Hexagonal-shaped Ir islands also formed upon heating 1.2 ML of √3 Ir beyond 830 °C, which resulted in the elimination of √3 structure from the surface. The transformation from √3 to (1 × 1) structure upon heating to 830 °C was an irreversible surface phase transition. Annealing > 2.0 ML of Ir in the √3 phase above the 830 °C disorder temperature, followed by cooling, produced a (3 × 1) structure. Subsequent heating and cooling through 830 °C give evidence for a reversible (3 × 1) to (1 × 1) phase transition.

Catalyst–substrate interaction and growth delay in vapor–liquid–solid nanowire growth

NASA Astrophysics Data System (ADS)

Kolíbal, Miroslav; Pejchal, Tomáš; Musálek, Tomáš; Šikola, Tomáš

2018-05-01

Understanding of the initial stage of nanowire growth on a bulk substrate is crucial for the rational design of nanowire building blocks in future electronic and optoelectronic devices. Here, we provide in situ scanning electron microscopy and Auger microscopy analysis of the initial stage of Au-catalyzed Ge nanowire growth on different substrates. Real-time microscopy imaging and elementally resolved spectroscopy clearly show that the catalyst dissolves the underlying substrate if held above a certain temperature. If the substrate dissolution is blocked (or in the case of heteroepitaxy) the catalyst needs to be filled with nanowire material from the external supply, which significantly increases the initial growth delay. The experiments presented here reveal the important role of the substrate in metal-catalyzed nanowire growth and pave the way for different growth delay mitigation strategies.

Monte Carlo simulation of the influence of pressure and target-substrate distance on the sputtering process for metal and semiconductor layers

NASA Astrophysics Data System (ADS)

Bouazza, Abdelkader; Settaouti, Abderrahmane

2016-07-01

The energy and the number of particles arriving at the substrate during physical vapor deposition (PVD) are in close relation with divers parameters. In this work, we present the influence of the distance between the target and substrate and the gas pressure in the sputtering process of deposited layers of metals (Cu, Al and Ag) and semiconductors (Ge, Te and Si) for substrate diameter of 40 cm and target diameter of 5 cm. The nascent sputter flux, the flux of the atoms and their energy arriving at the substrate have been simulated by Monte Carlo codes. A good agreement between previous works of other groups and our simulations for sputter pressures (0.3-1 Pa) and target-substrate distances (8-20 cm) is obtained.

Catalyst-substrate interaction and growth delay in vapor-liquid-solid nanowire growth.

PubMed

Kolíbal, Miroslav; Pejchal, Tomáš; Musálek, Tomáš; Šikola, Tomáš

2018-05-18

Understanding of the initial stage of nanowire growth on a bulk substrate is crucial for the rational design of nanowire building blocks in future electronic and optoelectronic devices. Here, we provide in situ scanning electron microscopy and Auger microscopy analysis of the initial stage of Au-catalyzed Ge nanowire growth on different substrates. Real-time microscopy imaging and elementally resolved spectroscopy clearly show that the catalyst dissolves the underlying substrate if held above a certain temperature. If the substrate dissolution is blocked (or in the case of heteroepitaxy) the catalyst needs to be filled with nanowire material from the external supply, which significantly increases the initial growth delay. The experiments presented here reveal the important role of the substrate in metal-catalyzed nanowire growth and pave the way for different growth delay mitigation strategies.

Ge quantum dot arrays grown by ultrahigh vacuum molecular-beam epitaxy on the Si(001) surface: nucleation, morphology, and CMOS compatibility.

PubMed

Yuryev, Vladimir A; Arapkina, Larisa V

2011-09-05

Issues of morphology, nucleation, and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (≲600°C) and high (≳600°C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts--pyramids and wedges-- are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.

Morphological evolution of Ge/Si(001) quantum dot rings formed at the rim of wet-etched pits.

PubMed

Grydlik, Martyna; Brehm, Moritz; Schäffler, Friedrich

2012-10-30

We demonstrate the formation of Ge quantum dots in ring-like arrangements around predefined {111}-faceted pits in the Si(001) substrate. We report on the complex morphological evolution of the single quantum dots contributing to the rings by means of atomic force microscopy and demonstrate that by careful adjustment of the epitaxial growth parameters, such rings containing densely squeezed islands can be grown with large spatial distances of up to 5 μm without additional nucleation of randomly distributed quantum dots between the rings.

A crystalline germanium flexible thin-film transistor

NASA Astrophysics Data System (ADS)

Higashi, H.; Nakano, M.; Kudo, K.; Fujita, Y.; Yamada, S.; Kanashima, T.; Tsunoda, I.; Nakashima, H.; Hamaya, K.

2017-11-01

We experimentally demonstrate a flexible thin-film transistor (TFT) with (111)-oriented crystalline germanium (Ge) layers grown by a gold-induced crystallization method. Accumulation-mode metal source/drain p-channel Ge TFTs are fabricated on a polyimide film at ≤ 400 ° C . A field-effect mobility (μFE) of 10.7 cm2/Vs is obtained, meaning the highest μFE in the p-TFTs fabricated at ≤ 400 ° C on flexible plastic substrates. This study will lead to high-performance flexible electronics based on an inorganic-semiconductor channel.

Direct molecular dynamics simulation of Ge deposition on amorphous SiO 2 at experimentally relevant conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chuang, Claire Y.; Zepeda-Ruiz, Luis A.; Han, Sang M.

2015-06-01

Molecular dynamics simulations were used to study Ge island nucleation and growth on amorphous SiO 2 substrates. This process is relevant in selective epitaxial growth of Ge on Si, for which SiO 2 is often used as a template mask. The islanding process was studied over a wide range of temperatures and fluxes, using a recently proposed empirical potential model for the Si–SiO 2–Ge system. The simulations provide an excellent quantitative picture of the Ge islanding and compare well with detailed experimental measurements. These quantitative comparisons were enabled by an analytical rate model as a bridge between simulations and experimentsmore » despite the fact that deposition fluxes accessible in simulations and experiments are necessarily different by many orders of magnitude. In particular, the simulations led to accurate predictions of the critical island size and the scaling of island density as a function of temperature. Lastly, the overall approach used here should be useful not just for future studies in this particular system, but also for molecular simulations of deposition in other materials.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makino, Nobuaki; Toshiba Corporation, 33 Shin-Isogo-Cho, Isogo-ku, Yokohama 235-0017; Shigeta, Yukichi

The stabilization of the amorphous structure in amorphous silicon film by adding Ge atoms was studied using Raman spectroscopy. Amorphous Si{sub 1−x}Ge{sub x} (x = 0.0, 0.03, 0.14, and 0.27) films were deposited on glass substrates from electron beam evaporation sources and annealed in N{sub 2} atmosphere. The change in the amorphous states and the phase transition from amorphous to crystalline were characterized using the TO, LO, and LA phonons in the Raman spectra. The temperature of the transition from the amorphous phase to the crystalline phase was higher for the a-Si{sub 1−x}Ge{sub x} (x = 0.03, 0.14) films, and the crystallization was hindered.more » The reason why the addition of a suitable quantity of Ge atoms into the three-dimensional amorphous silicon network stabilizes its amorphous structure is discussed based on the changes in the Raman signals of the TO, LO, and LA phonons during annealing. The characteristic bond length of the Ge atoms allows them to stabilize the random network of the amorphous Si composed of quasi-tetrahedral Si units, and obstruct its rearrangement.« less

Development of GaAs/Si and GaAs/Si monolithic structures for future space solar cells

NASA Technical Reports Server (NTRS)

Spitzer, M. B.; Vernon, S. M.; Wolfson, R. G.; Tobin, S. P.

1984-01-01

The results of heteroepitaxial growth of GaAs and GaAlAs directly on Si are presented, and applications to new cell structures are suggested. The novel feature is the elimination of a Ge lattice transition region. This feature not only reduces the cost of substrate preparation, but also makes possible the fabrication of high efficiency monolithic cascade structures. All films to be discussed were grown by organometallic chemical vapor deposition at atmospheric pressure. This process yielded reproducible, large-area films of GaAs, grown directly on Si, that are tightly adherent and smooth, and are characterized by a defect density of 5 x 10(6) power/sq cm. Preliminary studies indicate that GaAlAs can also be grown in this way. A number of promising applications are suggested. Certainly these substrates are ideal for low-weight GaAs space solar ells. For very high efficiency, the absence of Ge makes the technology attractive for GaAlAs/Si monolithic cascades, in which the Si substrates would first be provided with a suitable p/n junction. An evaluation of a three bandgap cascade consisting of appropriately designed GaAlAs/GaAs/Si layers is also presented.

Investigation of Low Cost Substrate Approaches for III-V Solar Cells

NASA Astrophysics Data System (ADS)

Lichty, Marlene Lydia

With the need for cleaner energy sources, which can displace fossil fuel, the solar cell industry is of particular interest due to the abundancy of the Sun. Silicon currently dominates terrestrial applications, but efficiency improvements have saturated. III-V based solar cells have reported the highest efficiencies, however, high costs due to substrates and fabrication processes have limited these devices to specialty applications, such as space. In order to reduce the cost associated with fabricating III-V semiconductor substrate material, two different approaches were taken in this work with a particular focus on making III-Vs more applicable outside of specialty applications, including InP, InAsnd Ge. Typical material characterization techniques were used to analyze the samples and processes studied in this thesis. The first process examined was the direct epitaxial growth of III-V materials by MOCVD on cheaper substrates. More specifically, the direct growth of InP and InAs on metal foils. A growth time study and surface coverage analysis was performed for the growth of InP. A characterization study was then conducted on the second process, the aluminum- induced crystallization of germanium to determine the effects this process had on the surface. Crystalline InP, InAs and Ge were successfully characterized in this work, and show promise for use in cheaper III-V alternatives to terrestrial energy solutions.

Effects of a GaSb buffer layer on an InGaAs overlayer grown on Ge(111) substrates: Strain, twin generation, and surface roughness

NASA Astrophysics Data System (ADS)

Kajikawa, Y.; Nishigaichi, M.; Tenma, S.; Kato, K.; Katsube, S.

2018-04-01

InGaAs layers were grown by molecular-beam epitaxy on nominal and vicinal Ge(111) substrates with inserting GaSb buffer layers. High-resolution X-ray diffraction using symmetric 333 and asymmetric 224 reflections was employed to analyze the crystallographic properties of the grown layers. By using the two reflections, we determined the lattice constants (the unit cell length a and the angle α between axes) of the grown layers with taking into account the rhombohedral distortion of the lattices of the grown layers. This allowed us the independent determination of the strain components (perpendicular and parallel components to the substrate surface, ε⊥ and ε//) and the composition x of the InxGa1-xAs layers by assuming the distortion coefficient D, which is defined as the ratio of ε⊥ against ε//. Furthermore, the twin ratios were determined for the GaSb and the InGaAs layers by comparing asymmetric 224 reflections from the twin domain with that from the normal domain of the layers. As a result, it has been shown that the twin ratio in the InGaAs layer can be decreased to be less than 0.1% by the use of the vicinal substrate together with annealing the GaSb buffer layer during the growth interruption before the InGaAs overgrowth.

Determination of the proton spin structure functions for 0.05

NASA Astrophysics Data System (ADS)

Fersch, R. G.; Guler, N.; Bosted, P.; Deur, A.; Griffioen, K.; Keith, C.; Kuhn, S. E.; Minehart, R.; Prok, Y.; Adhikari, K. P.; Adhikari, S.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Asryan, G.; Avakian, H.; Ball, J.; Balossino, I.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Thanh Cao, Frank; Carman, D. S.; Careccia, S.; Celentano, A.; Chandavar, S.; Charles, G.; Chetry, T.; Ciullo, G.; Clark, L.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Djalali, C.; Dodge, G. E.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Filippi, A.; Fleming, J. A.; Forest, T. A.; Garçon, M.; Gavalian, G.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gleason, C.; Golovatch, E.; Gothe, R. W.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Heddle, D.; Hicks, K.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Joo, K.; Keller, D.; Khachatryan, G.; Khachatryan, M.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kubarovsky, V.; Lagerquist, V. G.; Lanza, L.; Lenisa, P.; Livingston, K.; Lu, H. Y.; McKinnon, B.; Meyer, C. A.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Movsisyan, A.; Munoz Camacho, C.; Murdoch, G.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Paremuzyan, R.; Park, K.; Pasyuk, E.; Phelps, W.; Pierce, J.; Pisano, S.; Pogorelko, O.; Price, J. W.; Protopopescu, D.; Raue, B. A.; Ripani, M.; Riser, D.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schumacher, R. A.; Sharabian, Y. G.; Simonyan, A.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stankovic, I.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tian, Ye; Torayev, B.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Zachariou, N.; Zhang, J.; CLAS Collaboration

2017-12-01

We present the results of our final analysis of the full data set of g1p(Q2) , the spin structure function of the proton, collected using CLAS at Jefferson Laboratory in 2000-2001. Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.7 GeV were scattered from proton targets (NH153 dynamically polarized along the beam direction) and detected with CLAS. From the measured double spin asymmetries, we extracted virtual photon asymmetries A1p and A2p and spin structure functions g1p and g2p over a wide kinematic range (0.05 GeV2

Heteroepitaxial growth of GaAs on (100) Ge/Si using migration enhanced epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanoto, H.; Loke, W. K.; Yoon, S. F.

In this paper, heteroepitaxial growth of GaAs on nominal (100) Ge/Si substrate was investigated. The root-mean square surface roughness of the sample where the first few monolayers of the GaAs were nucleated by migration enhanced epitaxy (MEE) is four times smaller compared to the sample without such a process, indicating better surface planarity. From the (004) x-ray diffraction rocking curve measurement, the full width at half maximum of the GaAs layer nucleated by MEE is 40% lower compared to that of the GaAs layer without such a process, indicating better crystal quality. Furthermore, it was found that the sample wheremore » the GaAs layer was nucleated by MEE experienced early relaxation. As the MEE process promotes two-dimensional growth, the GaAs layer where nucleation was initiated by such a process has fewer islandlike formations. This leads to a pseudomorphically grown GaAs layer, which experiences higher strain compared to the GaAs layer with more islandlike formations, where most relaxation occurs on the free surface of the islands. Therefore, for the same layer thickness, the GaAs layer on (100) Ge/Si substrate where nucleation was initiated by MEE relaxed first.« less

Formation of SiGe nanocrystals embedded in Al2O3 for the application of write-once-read-many-times memory

NASA Astrophysics Data System (ADS)

Wu, Min-Lin; Wu, Yung-Hsien; Lin, Chia-Chun; Chen, Lun-Lun

2012-10-01

The structure of SiGe nanocrystals embedded in Al2O3 formed by sequential deposition of Al2O3/Si/Ge/Al2O3 and a subsequent annealing was confirmed by transmission electron microscopy and energy dispersive spectroscopy (EDS), and its application for write-once-read-many-times (WORM) memory devices was explored in this study. By applying a -10 V pulse for 1 s, a large amount of holes injected from Si substrate are stored in the nanocrystals and consequently, the current at +1.5 V increases by a factor of 104 as compared to that of the initial state. Even with a smaller -5 V pulse for 1 μs, a sufficiently large current ratio of 36 can still be obtained, verifying the low power operation. Since holes are stored in nanocrystals which are isolated from Si substrate by Al2O3 with good integrity and correspond to a large valence band offset with respect to Al2O3, desirable read endurance up to 105 cycles and excellent retention over 100 yr are achieved. Combining these promising characteristics, WORM memory devices are appropriate for high-performance archival storage applications.

Interwell coupling effect in Si/SiGe quantum wells grown by ultra high vacuum chemical vapor deposition

PubMed Central

Wang, Rui; Lu, Fen; Fan, Wei Jun; Liu, Chong Yang; Loh, Ter-Hoe; Nguyen, Hoai Son; Narayanan, Balasubramanian

2007-01-01

Si/Si0.66Ge0.34coupled quantum well (CQW) structures with different barrier thickness of 40, 4 and 2 nm were grown on Si substrates using an ultra high vacuum chemical vapor deposition (UHV-CVD) system. The samples were characterized using high resolution x-ray diffraction (HRXRD), cross-sectional transmission electron microscopy (XTEM) and photoluminescence (PL) spectroscopy. Blue shift in PL peak energy due to interwell coupling was observed in the CQWs following increase in the Si barrier thickness. The Si/SiGe heterostructure growth process and theoretical band structure model was validated by comparing the energy of the no-phonon peak calculated by the 6 + 2-bandk·pmethod with experimental PL data. Close agreement between theoretical calculations and experimental data was obtained.

Comparison of low frequency charge noise in identically patterned Si/SiO{sub 2} and Si/SiGe quantum dots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, Blake M.; Schoenfield, Joshua S.; Jiang, HongWen

We investigate and compare the charge noise in Si/SiO{sub 2} and Si/SiGe gate defined quantum dots with identically patterned gates by measuring the low frequency 1/f current noise through the biased quantum dots in the coulomb blockade regime. The current noise is normalized and used to extract a measurement of the potential energy noise in the system. Additionally, the temperature dependence of this noise is investigated. The measured charge noise in Si/SiO{sub 2} compares favorably with that of the SiGe device as well as previous measurements made on other substrates suggesting Si/SiO{sub 2} is a potential candidate for spin basedmore » quantum computing.« less

Interfacial, Electrical, and Band Alignment Characteristics of HfO2/Ge Stacks with In Situ-Formed SiO2 Interlayer by Plasma-Enhanced Atomic Layer Deposition

NASA Astrophysics Data System (ADS)

Cao, Yan-Qiang; Wu, Bing; Wu, Di; Li, Ai-Dong

2017-05-01

In situ-formed SiO2 was introduced into HfO2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO2/SiO2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation. In addition, it can also suppress the GeO2 degradation. The electrical measurements show that capacitance equivalent thickness of 1.53 nm and a leakage current density of 2.1 × 10-3 A/cm2 at gate bias of Vfb + 1 V was obtained for the annealed sample. The conduction (valence) band offsets at the HfO2/SiO2/Ge interface with and without PDA are found to be 2.24 (2.69) and 2.48 (2.45) eV, respectively. These results indicate that in situ PEALD SiO2 may be a promising interfacial control layer for the realization of high-quality Ge-based transistor devices. Moreover, it can be demonstrated that PEALD is a much more powerful technology for ultrathin interfacial control layer deposition than MOCVD.

Interfacial, Electrical, and Band Alignment Characteristics of HfO2/Ge Stacks with In Situ-Formed SiO2 Interlayer by Plasma-Enhanced Atomic Layer Deposition.

PubMed

Cao, Yan-Qiang; Wu, Bing; Wu, Di; Li, Ai-Dong

2017-12-01

In situ-formed SiO 2 was introduced into HfO 2 gate dielectrics on Ge substrate as interlayer by plasma-enhanced atomic layer deposition (PEALD). The interfacial, electrical, and band alignment characteristics of the HfO 2 /SiO 2 high-k gate dielectric stacks on Ge have been well investigated. It has been demonstrated that Si-O-Ge interlayer is formed on Ge surface during the in situ PEALD SiO 2 deposition process. This interlayer shows fantastic thermal stability during annealing without obvious Hf-silicates formation. In addition, it can also suppress the GeO 2 degradation. The electrical measurements show that capacitance equivalent thickness of 1.53 nm and a leakage current density of 2.1 × 10 -3 A/cm 2 at gate bias of V fb  + 1 V was obtained for the annealed sample. The conduction (valence) band offsets at the HfO 2 /SiO 2 /Ge interface with and without PDA are found to be 2.24 (2.69) and 2.48 (2.45) eV, respectively. These results indicate that in situ PEALD SiO 2 may be a promising interfacial control layer for the realization of high-quality Ge-based transistor devices. Moreover, it can be demonstrated that PEALD is a much more powerful technology for ultrathin interfacial control layer deposition than MOCVD.

Passivation of Ge/high-κ interface using RF Plasma nitridation

NASA Astrophysics Data System (ADS)

Dushaq, Ghada; Nayfeh, Ammar; Rasras, Mahmoud

2018-01-01

In this paper, plasma nitridation of a germanium surface using NH3 and N2 gases is performed with a standard RF-PECVD method at a substrate temperature of 250 °C. The structural and optical properties of the Ge surface have been investigated using Atomic Force Microscopy (AFM), Fourier Transform Infrared Spectroscopy (FT-IR), and Variable Angle Spectroscopic Ellipsometery (VASE). Study of the Ge (100) surface revealed that it is nitrated after plasma treatment while the GeO2 regrowth on the surface has been suppressed. Also, stability of the treated surface under air exposure is observed, where all the measurements were performed at room ambient. The electrical characteristics of fabricated Al/Ti/HfO2/GeON/p-Ge capacitors using the proposed surface treatment technique have been investigated. The C-V curves indicated a negligible hysteresis compared to ˜500 mV observed in untreated samples. Additionally, the C-V characteristic is used to extract the high-κ/Ge interface trap density using the most commonly used methods in determining the interface traps. The discussion includes the Dit calculation from the high-low frequency (Castagné-Vapaille) method and Terman (high-frequency) method. The high-low frequency method indicated a low interface trap density of ˜2.5 × 1011 eV-1.cm-2 compared to the Terman method. The J-V measurements revealed more than two orders of magnitude reduction of the gate leakage. This improved Ge interface quality is a promising low-temperature technique for fabricating high-performance Ge MOSFETs.

The composition dependence of magnetic, electronic and optical properties of Mn-doped SixGe1-x nanowires

NASA Astrophysics Data System (ADS)

Wei, Jianglin; Lan, Mu; Zhang, Xi; Xiang, Gang

2017-07-01

Mn-doped SixGe1-x nanowires (NWs) with different Ge concentrations have been studied by first-principles calculations. It is found that the spin dependent energy bands of the NWs show rich variations both in bandgap width and type (from indirect to direct) as the Ge concentration changes. The Mn-doped SixGe1-x NWs exhibit half-metallic characteristics for all Ge concentrations, and the ground states of the NWs are found to be ferromagnetic (FM). The net magnetization mapping and spin density of states calculations reveal that Mn 3d electrons have a strong hybridization effect with nearest Ge 4p electrons, which results in the Ge’s nontrivial contribution to the magnetic moment of the NWs. Further magnon dispersion studies show that the magnetic order stability of the NWs is influenced by Ge concentrations. Finally, the dependence of the optical properties of the magnetic NWs on the Ge concentration is demonstrated. Our results suggest that Mn-doped SixGe1-x NWs may be useful in spintronic and optoelectronic devices.

Auger-electron diffraction in the low kinetic-energy range: The Si(111)7×7 surface reconstruction and Ge/Si interface formation

NASA Astrophysics Data System (ADS)

de Crescenzi, M.; Gunnella, R.; Bernardini, R.; de Marco, M.; Davoli, I.

1995-07-01

We have investigated the Auger-electron diffraction (AED) of the L2,3VV Auger line of the clean 7×7 reconstructed Si(111) surface and the Ge/Si interface formed after a few monolayers (ML) of Ge deposition. The experimental AED in the low kinetic-energy regime has been interpreted within the framework of a multiple-scattering theory. The comparison of the AED data taken using both the x-ray source and an electron source evidences that the incident beam plays a negligible role when the experimental conditions require the use of an angular detector. The evolution of the Ge/Si(111) interface is studied by monitoring the intensity anisotropy of the Auger peaks of the two elements at room temperature (RT) and at 400 °C annealing temperature of the substrate. The evolution of the growth mechanism underlying the Ge/Si interface formation has been studied by exploiting the very low electron escape depth of this technique (<=5 Å). While at RT two monolayers of Ge deposition appear uniform and amorphous, the successive annealing induces an intermixing and a recrystallization only in the first two layers of the interface without any further interdiffusion. Furthermore, a Stranski-Krastanow growth mode has been deduced after deposition of 4 ML of Ge on a clean Si sample kept at 400 °C.

Effect of Sn Composition in Ge1- x Sn x Layers Grown by Using Rapid Thermal Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Kil, Yeon-Ho; Kang, Sukill; Jeong, Tae Soo; Shim, Kyu-Hwan; Kim, Dae-Jung; Choi, Yong-Dae; Kim, Mi Joung; Kim, Taek Sung

2018-05-01

The Ge1- x Sn x layers were grown by using rapid thermal chemical-vapor deposition (RTCVD) on boron-doped p-type Si (100) substrates with Sn compositions up to x = 0.83%. In order to obtain effect of the Sn composition on the structural and the optical characteristics, we utilized highresolution X-ray diffraction (HR-XRD), etch pit density (EPD), atomic force microscopy (AFM), Raman spectroscopy, and photocurrent (PC) spectra. The Sn compositions in the Ge1- x Sn x layers were found to be of x = 0.00%, 0.51%, 0.65%, and 0.83%. The root-mean-square (RMS) of the surface roughness of the Ge1- x Sn x layer increased from 2.02 nm to 3.40 nm as the Sn composition was increased from 0.51% to 0.83%, and EPD was on the order of 108 cm-2. The Raman spectra consist of only one strong peak near 300 cm-1, which is assigned to the Ge-Ge LO peaks and the Raman peaks shift to the wave number with increasing Sn composition. Photocurrent spectra show near energy band gap peaks and their peak energies decrease with increasing Sn composition due to band-gap bowing in the Ge1- x Sn x layer. An increase in the band gap bowing parameter was observed with increasing Sn composition.

Search for top squarks and dark matter particles in opposite-charge dilepton final states at s = 13 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.

A search for new physics is presented in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from b quarks, and missing transverse momentum (more » $$p_\\mathrm{T}^\\text{miss}$$). The search uses proton-proton collision data at $$\\sqrt{s}=$$ 13 TeV amounting to 35.9 fb$$^{-1}$$ of integrated luminosity collected using the CMS detector in 2016. Hypothetical signal events are efficiently separated from the dominant $$\\mathrm{t}\\overline{\\mathrm{t}}$$ background with requirements on $$p_\\mathrm{T}^\\text{miss}$$ and transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced top squarks. For top squarks, decaying exclusively to a top quark and a neutralino, exclusion limits are placed at 95\\% confidence level on the mass of the lightest top squark up to 800 GeV and on the lightest neutralino up to 360 GeV. These results, combined with searches in the single-lepton and all-jet final states, raise the exclusion limits up to 1050 GeV for the lightest top squark and up to 500 GeV for the lightest neutralino. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1300 GeV for top squarks and up to 800 GeV for the lightest neutralino. The results are also interpreted in a simplified model with a dark matter (DM) particle coupled to the top quark through a scalar or pseudoscalar mediator. For light DM, mediator masses up to 100 (50) GeV are excluded for scalar (pseudoscalar) mediators. The result for the scalar mediator achieves some of the most stringent limits to date in this model.« less

Search for top squarks and dark matter particles in opposite-charge dilepton final states at s = 13 TeV

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2018-02-15

A search for new physics is presented in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from b quarks, and missing transverse momentum (more » $$p_\\mathrm{T}^\\text{miss}$$). The search uses proton-proton collision data at $$\\sqrt{s}=$$ 13 TeV amounting to 35.9 fb$$^{-1}$$ of integrated luminosity collected using the CMS detector in 2016. Hypothetical signal events are efficiently separated from the dominant $$\\mathrm{t}\\overline{\\mathrm{t}}$$ background with requirements on $$p_\\mathrm{T}^\\text{miss}$$ and transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced top squarks. For top squarks, decaying exclusively to a top quark and a neutralino, exclusion limits are placed at 95\\% confidence level on the mass of the lightest top squark up to 800 GeV and on the lightest neutralino up to 360 GeV. These results, combined with searches in the single-lepton and all-jet final states, raise the exclusion limits up to 1050 GeV for the lightest top squark and up to 500 GeV for the lightest neutralino. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1300 GeV for top squarks and up to 800 GeV for the lightest neutralino. The results are also interpreted in a simplified model with a dark matter (DM) particle coupled to the top quark through a scalar or pseudoscalar mediator. For light DM, mediator masses up to 100 (50) GeV are excluded for scalar (pseudoscalar) mediators. The result for the scalar mediator achieves some of the most stringent limits to date in this model.« less

Magneto-transport Properties Using Top-Gated Hall Bars of Epitaxial Heterostructures on Single-Crystal SiGe Nanomembranes

NASA Astrophysics Data System (ADS)

Jacobson, R. B.; Li, Yize; Foote, Ryan; Cui, Xiaorui; Savage, Donald; Sookchoo, Pornsatit; Eriksson, Mark; Lagally, Max

2014-03-01

A high-quality 2-dimensional electron gas (2DEG) is crucial for quantum electronics and spintronics. Grown heterostructures on SiGe nanomembranes (NMs) show promise to create these 2DEG structures because they have reduced strain inhomogeneities and mosaic tilt. We investigate charge transport properties of these SiGe NMs/heterostructures over a range of temperatures and compare them with results from heterostructures grown on compositionally graded SiGe substrates. Measurements are done by creating Hall bars with top gates on the samples. From the magneto-transport data, low-carrier-density mobility values are calculated. Initial results on the grown heterostructures give a typical curve for mobility versus carrier density, but extraction of the zero-carrier-density mobility is dependent on the curve-fitting technique. Sponsored by United States Department of Defense. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the U.S. Government.

Workshop on Heteroepitaxial InP Solar Cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Walters, R. W.

1993-01-01

In a generic sense, the justification for any sort of InP solar cell research applies, i.e. to take advantage of the inherently high radiation resistance and efficiency of InP solar cells. To be more specific, the approach is justified by its potential for significant cost reduction and the availability of greatly increased cell area afforded by substrates such as Si and Ge. The use of substrates, such as the latter two, would result in increased ruggedness, ease of handling, and improved manufacturability. The use of more rugged substrates would lead to a greatly increased capability for cell thinning leading to the desirable feature of reduced array weight.

Ge quantum dot arrays grown by ultrahigh vacuum molecular-beam epitaxy on the Si(001) surface: nucleation, morphology, and CMOS compatibility

PubMed Central

2011-01-01

Issues of morphology, nucleation, and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (≲600°C) and high (≳600°C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts--pyramids and wedges-- are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature. PMID:21892938

High Efficiency Photovoltaic and Plasmonic Devices

DTIC Science & Technology

2011-07-01

on Si or SOI substrate along with its band alignment. This elongated mesa forms a strip channel aveguide……………………………….…4 Figure 3 Radiative and...lattice matched GeSn relaxed buffer on Si or SOI substrate along with its band alignment. This elongated mesa forms a strip channel waveguide...Appl. Phys. Lett. 90, 251105 (2007). 8. R. A. Soref and C. H. Perry, J. Appl. Phys. 69, 539 (1991). 9. H. P. L. de Guevara, A. G. Rodriguez , H

Delayed plastic relaxation limit in SiGe islands grown by Ge diffusion from a local source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vanacore, G. M.; Zani, M.; Tagliaferri, A., E-mail: alberto.tagliaferri@polimi.it

2015-03-14

The hetero-epitaxial strain relaxation in nano-scale systems plays a fundamental role in shaping their properties. Here, the elastic and plastic relaxation of self-assembled SiGe islands grown by surface-thermal-diffusion from a local Ge solid source on Si(100) are studied by atomic force and transmission electron microscopies, enabling the simultaneous investigation of the strain relaxation in different dynamical regimes. Islands grown by this technique remain dislocation-free and preserve a structural coherence with the substrate for a base width as large as 350 nm. The results indicate that a delay of the plastic relaxation is promoted by an enhanced Si-Ge intermixing, induced by themore » surface-thermal-diffusion, which takes place already in the SiGe overlayer before the formation of a critical nucleus. The local entropy of mixing dominates, leading the system toward a thermodynamic equilibrium, where non-dislocated, shallow islands with a low residual stress are energetically stable. These findings elucidate the role of the interface dynamics in modulating the lattice distortion at the nano-scale, and highlight the potential use of our growth strategy to create composition and strain-controlled nano-structures for new-generation devices.« less

XPS-XRF hybrid metrology enabling FDSOI process

NASA Astrophysics Data System (ADS)

Hossain, Mainul; Subramanian, Ganesh; Triyoso, Dina; Wahl, Jeremy; Mcardle, Timothy; Vaid, Alok; Bello, A. F.; Lee, Wei Ti; Klare, Mark; Kwan, Michael; Pois, Heath; Wang, Ying; Larson, Tom

2016-03-01

Planar fully-depleted silicon-on-insulator (FDSOI) technology potentially offers comparable transistor performance as FinFETs. pFET FDOSI devices are based on a silicon germanium (cSiGe) layer on top of a buried oxide (BOX). Ndoped interfacial layer (IL), high-k (HfO2) layer and the metal gate stacks are then successively built on top of the SiGe layer. In-line metrology is critical in precisely monitoring the thickness and composition of the gate stack and associated underlying layers in order to achieve desired process control. However, any single in-line metrology technique is insufficient to obtain the thickness of IL, high-k, cSiGe layers in addition to Ge% and N-dose in one single measurement. A hybrid approach is therefore needed that combines the capabilities of more than one measurement technique to extract multiple parameters in a given film stack. This paper will discuss the approaches, challenges, and results associated with the first-in-industry implementation of XPS-XRF hybrid metrology for simultaneous detection of high-k thickness, IL thickness, N-dose, cSiGe thickness and %Ge, all in one signal measurement on a FDSOI substrate in a manufacturing fab. Strong correlation to electrical data for one or more of these measured parameters will also be presented, establishing the reliability of this technique.

Search for a supersymmetric partner to the top quark in final states with jets and missing transverse momentum at sqrt[s] = 7 TeV with the ATLAS detector.

PubMed

Aad, G; Abajyan, T; Abbott, B; Abdallah, J; Abdel Khalek, S; Abdelalim, A A; Abdinov, O; Aben, R; Abi, B; Abolins, M; Abouzeid, O S; Abramowicz, H; Abreu, H; Acharya, B S; Adamczyk, L; Adams, D L; Addy, T N; Adelman, J; Adomeit, S; Adragna, P; Adye, T; Aefsky, S; Aguilar-Saavedra, J A; Agustoni, M; Aharrouche, M; Ahlen, S P; Ahles, F; Ahmad, A; Ahsan, M; Aielli, G; Akdogan, T; Akesson, T P A; Akimoto, G; Akimov, A V; Alam, M S; Alam, M A; Albert, J; Albrand, S; Aleksa, M; Aleksandrov, I N; Alessandria, F; Alexa, C; Alexander, G; Alexandre, G; Alexopoulos, T; Alhroob, M; Aliev, M; Alimonti, G; Alison, J; Allbrooke, B M M; Allport, P P; Allwood-Spiers, S E; Almond, J; Aloisio, A; Alon, R; Alonso, A; Alonso, F; Altheimer, A; Alvarez Gonzalez, B; Alviggi, M G; Amako, K; Amelung, C; Ammosov, V V; Amor Dos Santos, S P; Amorim, A; Amram, N; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anderson, K J; Andreazza, A; Andrei, V; Anduaga, X S; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A; Anjos, N; Annovi, A; Antonaki, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aoun, S; Aperio Bella, L; Apolle, R; Arabidze, G; Aracena, I; Arai, Y; Arce, A T H; Arfaoui, S; Arguin, J-F; Arik, E; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Arnault, C; Artamonov, A; Artoni, G; Arutinov, D; Asai, S; Asfandiyarov, R; Ask, S; Asman, B; Asquith, L; Assamagan, K; Astbury, A; Atkinson, M; Aubert, B; Auge, E; Augsten, K; Aurousseau, M; Avolio, G; Avramidou, R; Axen, D; Azuelos, G; Azuma, Y; Baak, M A; Baccaglioni, G; Bacci, C; Bach, A M; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Badescu, E; Bagnaia, P; Bahinipati, S; Bai, Y; Bailey, D C; Bain, T; Baines, J T; Baker, O K; Baker, M D; Baker, S; Banas, E; Banerjee, P; Banerjee, Sw; Banfi, D; Bangert, A; Bansal, V; Bansil, H S; Barak, L; Baranov, S P; Barbaro Galtieri, A; Barber, T; Barberio, E L; Barberis, D; Barbero, M; Bardin, D Y; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnett, B M; Barnett, R M; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Barrillon, P; Bartoldus, R; Barton, A E; Bartsch, V; Basye, A; Bates, R L; Batkova, L; Batley, J R; Battaglia, A; Battistin, M; Bauer, F; Bawa, H S; Beale, S; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, A K; Becker, S; Beckingham, M; Becks, K H; Beddall, A J; Beddall, A; Bedikian, S; Bednyakov, V A; Bee, C P; Beemster, L J; Begel, M; Behar Harpaz, S; Beimforde, M; Belanger-Champagne, C; Bell, P J; Bell, W H; Bella, G; Bellagamba, L; Bellina, F; Bellomo, M; Belloni, A; Beloborodova, O; Belotskiy, K; Beltramello, O; Benary, O; Benchekroun, D; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Benoit, M; Bensinger, J R; Benslama, K; Bentvelsen, S; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Berglund, E; Beringer, J; Bernat, P; Bernhard, R; Bernius, C; Berry, T; Bertella, C; Bertin, A; Bertolucci, F; Besana, M I; Besjes, G J; Besson, N; Bethke, S; Bhimji, W; Bianchi, R M; Bianco, M; Biebel, O; Bieniek, S P; Bierwagen, K; Biesiada, J; Biglietti, M; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biscarat, C; Bittner, B; Black, K M; Blair, R E; Blanchard, J-B; Blanchot, G; Blazek, T; Bloch, I; Blocker, C; Blocki, J; Blondel, A; Blum, W; Blumenschein, U; Bobbink, G J; Bobrovnikov, V B; Bocchetta, S S; Bocci, A; Boddy, C R; Boehler, M; Boek, J; Boelaert, N; Bogaerts, J A; Bogdanchikov, A; Bogouch, A; Bohm, C; Bohm, J; Boisvert, V; Bold, T; Boldea, V; Bolnet, N M; Bomben, M; Bona, M; Boonekamp, M; Bordoni, S; Borer, C; Borisov, A; Borissov, G; Borjanovic, I; Borri, M; Borroni, S; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Boterenbrood, H; Bouchami, J; Boudreau, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Bousson, N; Boveia, A; Boyd, J; Boyko, I R; Bozovic-Jelisavcic, I; Bracinik, J; Branchini, P; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brazzale, S F; Brelier, B; Bremer, J; Brendlinger, K; Brenner, R; Bressler, S; Britton, D; Brochu, F M; Brock, I; Brock, R; Broggi, F; Bromberg, C; Bronner, J; Brooijmans, G; Brooks, T; Brooks, W K; Brown, G; Brown, H; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Brunet, S; Bruni, A; Bruni, G; Bruschi, M; Buanes, T; Buat, Q; Bucci, F; Buchanan, J; Buchholz, P; Buckingham, R M; Buckley, A G; Buda, S I; Budagov, I A; Budick, B; Büscher, V; Bugge, L; Bulekov, O; Bundock, A C; Bunse, M; Buran, T; Burckhart, H; Burdin, S; Burgess, T; Burke, S; Busato, E; Bussey, P; Buszello, C P; Butler, B; Butler, J M; Buttar, C M; Butterworth, J M; Buttinger, W; Cabrera Urbán, S; Caforio, D; Cakir, O; Calafiura, P; Calderini, G; Calfayan, P; Calkins, R; Caloba, L P; Caloi, R; Calvet, D; Calvet, S; Camacho Toro, R; Camarri, P; Cameron, D; Caminada, L M; Caminal Armadans, R; Campana, S; Campanelli, M; Canale, V; Canelli, F; Canepa, A; Cantero, J; Cantrill, R; Capasso, L; Capeans Garrido, M D M; Caprini, I; Caprini, M; Capriotti, D; Capua, M; Caputo, R; Cardarelli, R; Carli, T; Carlino, G; Carminati, L; Caron, B; Caron, S; Carquin, E; Carrillo Montoya, G D; Carter, A A; Carter, J R; Carvalho, J; Casadei, D; Casado, M P; Cascella, M; Caso, C; Castaneda Hernandez, A M; Castaneda-Miranda, E; Castillo Gimenez, V; Castro, N F; Cataldi, G; Catastini, P; Catinaccio, A; Catmore, J R; Cattai, A; Cattani, G; Caughron, S; Cavaliere, V; Cavalleri, P; Cavalli, D; Cavalli-Sforza, M; Cavasinni, V; Ceradini, F; Cerqueira, A S; Cerri, A; Cerrito, L; Cerutti, F; Cetin, S A; Chafaq, A; Chakraborty, D; Chalupkova, I; Chan, K; Chang, P; Chapleau, B; Chapman, J D; Chapman, J W; Chareyre, E; Charlton, D G; Chavda, V; Chavez Barajas, C A; Cheatham, S; Chekanov, S; Chekulaev, S V; Chelkov, G A; Chelstowska, M A; Chen, C; Chen, H; Chen, S; Chen, X; Chen, Y; Cheplakov, A; Cherkaoui El Moursli, R; Chernyatin, V; Cheu, E; Cheung, S L; Chevalier, L; Chiefari, G; Chikovani, L; Childers, J T; Chilingarov, A; Chiodini, G; Chisholm, A S; Chislett, R T; Chitan, A; Chizhov, M V; Choudalakis, G; Chouridou, S; Christidi, I A; Christov, A; Chromek-Burckhart, D; Chu, M L; Chudoba, J; Ciapetti, G; Ciftci, A K; Ciftci, R; Cinca, D; Cindro, V; Ciocca, C; Ciocio, A; Cirilli, M; Cirkovic, P; Citron, Z H; Citterio, M; Ciubancan, M; Clark, A; Clark, P J; Clarke, R N; Cleland, W; Clemens, J C; Clement, B; Clement, C; Coadou, Y; Cobal, M; Coccaro, A; Cochran, J; Coffey, L; Cogan, J G; Coggeshall, J; Cogneras, E; Colas, J; Cole, S; Colijn, A P; Collins, N J; Collins-Tooth, C; Collot, J; Colombo, T; Colon, G; Conde Muiño, P; Coniavitis, E; Conidi, M C; Consonni, S M; Consorti, V; Constantinescu, S; Conta, C; Conti, G; Conventi, F; Cooke, M; Cooper, B D; Cooper-Sarkar, A M; Copic, K; Cornelissen, T; Corradi, M; Corriveau, F; Cortes-Gonzalez, A; Cortiana, G; Costa, G; Costa, M J; Costanzo, D; Côté, D; Courneyea, L; Cowan, G; Cowden, C; Cox, B E; Cranmer, K; Crescioli, F; Cristinziani, M; Crosetti, G; Crépé-Renaudin, S; Cuciuc, C-M; Cuenca Almenar, C; Cuhadar Donszelmann, T; Curatolo, M; Curtis, C J; Cuthbert, C; Cwetanski, P; Czirr, H; Czodrowski, P; Czyczula, Z; D'Auria, S; D'Onofrio, M; D'Orazio, A; Da Cunha Sargedas De Sousa, M J; Da Via, C; Dabrowski, W; Dafinca, A; Dai, T; Dallapiccola, C; Dam, M; Dameri, M; Damiani, D S; Danielsson, H O; Dao, V; Darbo, G; Darlea, G L; Dassoulas, J A; Davey, W; Davidek, T; Davidson, N; Davidson, R; Davies, E; Davies, M; Davignon, O; Davison, A R; Davygora, Y; Dawe, E; Dawson, I; Daya-Ishmukhametova, R K; De, K; de Asmundis, R; De Castro, S; De Cecco, S; de Graat, J; De Groot, N; de Jong, P; De La Taille, C; De la Torre, H; De Lorenzi, F; de Mora, L; De Nooij, L; De Pedis, D; De Salvo, A; De Sanctis, U; De Santo, A; De Vivie De Regie, J B; De Zorzi, G; Dearnaley, W J; Debbe, R; Debenedetti, C; Dechenaux, B; Dedovich, D V; Degenhardt, J; Del Papa, C; Del Peso, J; Del Prete, T; Delemontex, T; Deliyergiyev, M; Dell'acqua, A; Dell'asta, L; Della Pietra, M; Della Volpe, D; Delmastro, M; Delsart, P A; Deluca, C; Demers, S; Demichev, M; Demirkoz, B; Deng, J; Denisov, S P; Derendarz, D; Derkaoui, J E; Derue, F; Dervan, P; Desch, K; Devetak, E; Deviveiros, P O; Dewhurst, A; Dewilde, B; Dhaliwal, S; Dhullipudi, R; Di Ciaccio, A; Di Ciaccio, L; Di Girolamo, A; Di Girolamo, B; Di Luise, S; Di Mattia, A; Di Micco, B; Di Nardo, R; Di Simone, A; Di Sipio, R; Diaz, M A; Diehl, E B; Dietrich, J; Dietzsch, T A; Diglio, S; Dindar Yagci, K; Dingfelder, J; Dinut, F; Dionisi, C; Dita, P; Dita, S; Dittus, F; Djama, F; Djobava, T; do Vale, M A B; Do Valle Wemans, A; Doan, T K O; Dobbs, M; Dobinson, R; Dobos, D; Dobson, E; Dodd, J; Doglioni, C; Doherty, T; Doi, Y; Dolejsi, J; Dolenc, I; Dolezal, Z; Dolgoshein, B A; Dohmae, T; Donadelli, M; Donini, J; Dopke, J; Doria, A; Dos Anjos, A; Dotti, A; Dova, M T; Doxiadis, A D; Doyle, A T; Dris, M; Dubbert, J; Dube, S; Duchovni, E; Duckeck, G; Duda, D; Dudarev, A; Dudziak, F; Dührssen, M; Duerdoth, I P; Duflot, L; Dufour, M-A; Duguid, L; Dunford, M; Duran Yildiz, H; Duxfield, R; Dwuznik, M; Dydak, F; Düren, M; Ebke, J; Eckweiler, S; Edmonds, K; Edson, W; Edwards, C A; Edwards, N C; Ehrenfeld, W; Eifert, T; Eigen, G; Einsweiler, K; Eisenhandler, E; Ekelof, T; El Kacimi, M; Ellert, M; Elles, S; Ellinghaus, F; Ellis, K; Ellis, N; Elmsheuser, J; Elsing, M; Emeliyanov, D; Engelmann, R; Engl, A; Epp, B; Erdmann, J; Ereditato, A; Eriksson, D; Ernst, J; Ernst, M; Ernwein, J; Errede, D; Errede, S; Ertel, E; Escalier, M; Esch, H; Escobar, C; Espinal Curull, X; Esposito, B; Etienne, F; Etienvre, A I; Etzion, E; Evangelakou, D; Evans, H; Fabbri, L; Fabre, C; Fakhrutdinov, R M; Falciano, S; Fang, Y; Fanti, M; Farbin, A; Farilla, A; Farley, J; Farooque, T; Farrell, S; Farrington, S M; Farthouat, P; Fassi, F; Fassnacht, P; Fassouliotis, D; Fatholahzadeh, B; Favareto, A; Fayard, L; Fazio, S; Febbraro, R; Federic, P; Fedin, O L; Fedorko, W; Fehling-Kaschek, M; Feligioni, L; Fellmann, D; Feng, C; Feng, E J; Fenyuk, A B; Ferencei, J; Fernando, W; Ferrag, S; Ferrando, J; Ferrara, V; Ferrari, A; Ferrari, P; Ferrari, R; Ferreira de Lima, D E; Ferrer, A; Ferrere, D; Ferretti, C; Ferretto Parodi, A; Fiascaris, M; Fiedler, F; Filipčič, A; Filthaut, F; Fincke-Keeler, M; Fiolhais, M C N; Fiorini, L; Firan, A; Fischer, G; Fisher, M J; Flechl, M; Fleck, I; Fleckner, J; Fleischmann, P; Fleischmann, S; Flick, T; Floderus, A; Flores Castillo, L R; Flowerdew, M J; Fonseca Martin, T; Formica, A; Forti, A; Fortin, D; Fournier, D; Fox, H; Francavilla, P; Franchini, M; Franchino, S; Francis, D; Frank, T; Franz, S; Fraternali, M; Fratina, S; French, S T; Friedrich, C; Friedrich, F; Froeschl, R; Froidevaux, D; Frost, J A; Fukunaga, C; Fullana Torregrosa, E; Fulsom, B G; Fuster, J; Gabaldon, C; Gabizon, O; Gadfort, T; Gadomski, S; Gagliardi, G; Gagnon, P; Galea, C; Galhardo, B; Gallas, E J; Gallo, V; Gallop, B J; Gallus, P; Gan, K K; Gao, Y S; Gaponenko, A; Garberson, F; Garcia-Sciveres, M; García, C; García Navarro, J E; Gardner, R W; Garelli, N; Garitaonandia, H; Garonne, V; Gatti, C; Gaudio, G; Gaur, B; Gauthier, L; Gauzzi, P; Gavrilenko, I L; Gay, C; Gaycken, G; Gazis, E N; Ge, P; Gecse, Z; Gee, C N P; Geerts, D A A; Geich-Gimbel, Ch; Gellerstedt, K; Gemme, C; Gemmell, A; Genest, M H; Gentile, S; George, M; George, S; Gerlach, P; Gershon, A; Geweniger, C; Ghazlane, H; Ghodbane, N; Giacobbe, B; Giagu, S; Giakoumopoulou, V; Giangiobbe, V; Gianotti, F; Gibbard, B; Gibson, A; Gibson, S M; Gillberg, D; Gillman, A R; Gingrich, D M; Ginzburg, J; Giokaris, N; Giordani, M P; Giordano, R; Giorgi, F M; Giovannini, P; Giraud, P F; Giugni, D; Giunta, M; Giusti, P; Gjelsten, B K; Gladilin, L K; Glasman, C; Glatzer, J; Glazov, A; Glitza, K W; Glonti, G L; Goddard, J R; Godfrey, J; Godlewski, J; Goebel, M; Göpfert, T; Goeringer, C; Gössling, C; Goldfarb, S; Golling, T; Gomes, A; Gomez Fajardo, L S; Gonçalo, R; Goncalves Pinto Firmino Da Costa, J; Gonella, L; González de la Hoz, S; Gonzalez Parra, G; Gonzalez Silva, M L; Gonzalez-Sevilla, S; Goodson, J J; Goossens, L; Gorbounov, P A; Gordon, H A; Gorelov, I; Gorfine, G; Gorini, B; Gorini, E; Gorišek, A; Gornicki, E; Gosdzik, B; Goshaw, A T; Gosselink, M; Gostkin, M I; Gough Eschrich, I; Gouighri, M; Goujdami, D; Goulette, M P; Goussiou, A G; Goy, C; Gozpinar, S; Grabowska-Bold, I; Grafström, P; Grahn, K-J; Grancagnolo, F; Grancagnolo, S; Grassi, V; Gratchev, V; Grau, N; Gray, H M; Gray, J A; Graziani, E; Grebenyuk, O G; Greenshaw, T; Greenwood, Z D; Gregersen, K; Gregor, I M; Grenier, P; Griffiths, J; Grigalashvili, N; Grillo, A A; Grinstein, S; Gris, Ph; Grishkevich, Y V; Grivaz, J-F; Gross, E; Grosse-Knetter, J; Groth-Jensen, J; Grybel, K; Guest, D; Guicheney, C; Guindon, S; Gul, U; Guler, H; Gunther, J; Guo, B; Guo, J; Gutierrez, P; Guttman, N; Gutzwiller, O; Guyot, C; Gwenlan, C; Gwilliam, C B; Haas, A; Haas, S; Haber, C; Hadavand, H K; Hadley, D R; Haefner, P; Hahn, F; Haider, S; Hajduk, Z; Hakobyan, H; Hall, D; Haller, J; Hamacher, K; Hamal, P; Hamer, M; Hamilton, A; Hamilton, S; Han, L; Hanagaki, K; Hanawa, K; Hance, M; Handel, C; Hanke, P; Hansen, J R; Hansen, J B; Hansen, J D; Hansen, P H; Hansson, P; Hara, K; Hare, G A; Harenberg, T; Harkusha, S; Harper, D; Harrington, R D; Harris, O M; Hartert, J; Hartjes, F; Haruyama, T; Harvey, A; Hasegawa, S; Hasegawa, Y; Hassani, S; Haug, S; Hauschild, M; Hauser, R; Havranek, M; Hawkes, C M; Hawkings, R J; Hawkins, A D; Hayakawa, T; Hayashi, T; Hayden, D; Hays, C P; Hayward, H S; Haywood, S J; Head, S J; Hedberg, V; Heelan, L; Heim, S; Heinemann, B; Heisterkamp, S; Helary, L; Heller, C; Heller, M; Hellman, S; Hellmich, D; Helsens, C; Henderson, R C W; Henke, M; Henrichs, A; Henriques Correia, A M; Henrot-Versille, S; Hensel, C; Henß, T; Hernandez, C M; Hernández Jiménez, Y; Herrberg, R; Herten, G; Hertenberger, R; Hervas, L; Hesketh, G G; Hessey, N P; Higón-Rodriguez, E; Hill, J C; Hiller, K H; Hillert, S; Hillier, S J; Hinchliffe, I; Hines, E; Hirose, M; Hirsch, F; Hirschbuehl, D; Hobbs, J; Hod, N; Hodgkinson, M C; Hodgson, P; Hoecker, A; Hoeferkamp, M R; Hoffman, J; Hoffmann, D; Hohlfeld, M; Holder, M; Holmgren, S O; Holy, T; Holzbauer, J L; Hong, T M; Hooft van Huysduynen, L; Horner, S; Hostachy, J-Y; Hou, S; Hoummada, A; Howard, J; Howarth, J; Hristova, I; Hrivnac, J; Hryn'ova, T; Hsu, P J; Hsu, S-C; Hu, D; Hubacek, Z; Hubaut, F; Huegging, F; Huettmann, A; Huffman, T B; Hughes, E W; Hughes, G; Huhtinen, M; Hurwitz, M; Husemann, U; Huseynov, N; Huston, J; Huth, J; Iacobucci, G; Iakovidis, G; Ibbotson, M; Ibragimov, I; Iconomidou-Fayard, L; Idarraga, J; Iengo, P; Igonkina, O; Ikegami, Y; Ikeno, M; Iliadis, D; Ilic, N; Ince, T; Inigo-Golfin, J; Ioannou, P; Iodice, M; Iordanidou, K; Ippolito, V; Irles Quiles, A; Isaksson, C; Ishino, M; Ishitsuka, M; Ishmukhametov, R; Issever, C; Istin, S; Ivashin, A V; Iwanski, W; Iwasaki, H; Izen, J M; Izzo, V; Jackson, B; Jackson, J N; Jackson, P; Jaekel, M R; Jain, V; Jakobs, K; Jakobsen, S; Jakoubek, T; Jakubek, J; Jana, D K; Jansen, E; Jansen, H; Jantsch, A; Janus, M; Jarlskog, G; Jeanty, L; Jen-La Plante, I; Jennens, D; Jenni, P; Loevschall-Jensen, A E; Jež, P; Jézéquel, S; Jha, M K; Ji, H; Ji, W; Jia, J; Jiang, Y; Jimenez Belenguer, M; Jin, S; Jinnouchi, O; Joergensen, M D; Joffe, D; Johansen, M; Johansson, K E; Johansson, P; Johnert, S; Johns, K A; Jon-And, K; Jones, G; Jones, R W L; Jones, T J; Joram, C; Jorge, P M; Joshi, K D; Jovicevic, J; Jovin, T; Ju, X; Jung, C A; Jungst, R M; Juranek, V; Jussel, P; Juste Rozas, A; Kabana, S; Kaci, M; Kaczmarska, A; Kadlecik, P; Kado, M; Kagan, H; Kagan, M; Kajomovitz, E; Kalinin, S; Kalinovskaya, L V; Kama, S; Kanaya, N; Kaneda, M; Kaneti, S; Kanno, T; Kantserov, V A; Kanzaki, J; Kaplan, B; Kapliy, A; Kaplon, J; Kar, D; Karagounis, M; Karakostas, K; Karnevskiy, M; Kartvelishvili, V; Karyukhin, A N; Kashif, L; Kasieczka, G; Kass, R D; Kastanas, A; Kataoka, M; Kataoka, Y; Katsoufis, E; Katzy, J; Kaushik, V; Kawagoe, K; Kawamoto, T; Kawamura, G; Kayl, M S; Kazama, S; Kazanin, V A; Kazarinov, M Y; Keeler, R; Kehoe, R; Keil, M; Kekelidze, G D; Keller, J S; Kenyon, M; Kepka, O; Kerschen, N; Kerševan, B P; Kersten, S; Kessoku, K; Keung, J; Khalil-Zada, F; Khandanyan, H; Khanov, A; Kharchenko, D; Khodinov, A; Khomich, A; Khoo, T J; Khoriauli, G; Khoroshilov, A; Khovanskiy, V; Khramov, E; Khubua, J; Kim, H; Kim, S H; Kimura, N; Kind, O; King, B T; King, M; King, R S B; Kirk, J; Kiryunin, A E; Kishimoto, T; Kisielewska, D; Kitamura, T; Kittelmann, T; Kiuchi, K; Kladiva, E; Klein, M; Klein, U; Kleinknecht, K; Klemetti, M; Klier, A; Klimek, P; Klimentov, A; Klingenberg, R; Klinger, J A; Klinkby, E B; Klioutchnikova, T; Klok, P F; Klous, S; Kluge, E-E; Kluge, T; Kluit, P; Kluth, S; Knecht, N S; Kneringer, E; Knoops, E B F G; Knue, A; Ko, B R; Kobayashi, T; Kobel, M; Kocian, M; Kodys, P; Köneke, K; König, A C; Koenig, S; Köpke, L; Koetsveld, F; Koevesarki, P; Koffas, T; Koffeman, E; Kogan, L A; Kohlmann, S; Kohn, F; Kohout, Z; Kohriki, T; Koi, T; Kolachev, G M; Kolanoski, H; Kolesnikov, V; Koletsou, I; Koll, J; Komar, A A; Komori, Y; Kondo, T; Kono, T; Kononov, A I; Konoplich, R; Konstantinidis, N; Koperny, S; Korcyl, K; Kordas, K; Korn, A; Korol, A; Korolkov, I; Korolkova, E V; Korotkov, V A; Kortner, O; Kortner, S; Kostyukhin, V V; Kotov, S; Kotov, V M; Kotwal, A; Kourkoumelis, C; Kouskoura, V; Koutsman, A; Kowalewski, R; Kowalski, T Z; Kozanecki, W; Kozhin, A S; Kral, V; Kramarenko, V A; Kramberger, G; Krasny, M W; Krasznahorkay, A; Kraus, J K; Kreiss, S; Krejci, F; Kretzschmar, J; Krieger, N; Krieger, P; Kroeninger, K; Kroha, H; Kroll, J; Kroseberg, J; Krstic, J; Kruchonak, U; Krüger, H; Kruker, T; Krumnack, N; Krumshteyn, Z V; Kubota, T; Kuday, S; Kuehn, S; Kugel, A; Kuhl, T; Kuhn, D; Kukhtin, V; Kulchitsky, Y; Kuleshov, S; Kummer, C; Kuna, M; Kunkle, J; Kupco, A; Kurashige, H; Kurata, M; Kurochkin, Y A; Kus, V; Kuwertz, E S; Kuze, M; Kvita, J; Kwee, R; La Rosa, A; La Rotonda, L; Labarga, L; Labbe, J; Lablak, S; Lacasta, C; Lacava, F; Lacker, H; Lacour, D; Lacuesta, V R; Ladygin, E; Lafaye, R; Laforge, B; Lagouri, T; Lai, S; Laisne, E; Lamanna, M; Lambourne, L; Lampen, C L; Lampl, W; Lancon, E; Landgraf, U; Landon, M P J; Lane, J L; Lang, V S; Lange, C; Lankford, A J; Lanni, F; Lantzsch, K; Laplace, S; Lapoire, C; Laporte, J F; Lari, T; Larner, A; Lassnig, M; Laurelli, P; Lavorini, V; Lavrijsen, W; Laycock, P; Le Dortz, O; Le Guirriec, E; Le Menedeu, E; Lecompte, T; Ledroit-Guillon, F; Lee, H; Lee, J S H; Lee, S C; Lee, L; Lefebvre, M; Legendre, M; Legger, F; Leggett, C; Lehmacher, M; Lehmann Miotto, G; Lei, X; Leite, M A L; Leitner, R; Lellouch, D; Lemmer, B; Lendermann, V; Leney, K J C; Lenz, T; Lenzen, G; Lenzi, B; Leonhardt, K; Leontsinis, S; Lepold, F; Leroy, C; Lessard, J-R; Lester, C G; Lester, C M; Levêque, J; Levin, D; Levinson, L J; Lewis, A; Lewis, G H; Leyko, A M; Leyton, M; Li, B; Li, H; Li, S; Li, X; Liang, Z; Liao, H; Liberti, B; Lichard, P; Lichtnecker, M; Lie, K; Liebig, W; Limbach, C; Limosani, A; Limper, M; Lin, S C; Linde, F; Linnemann, J T; Lipeles, E; Lipniacka, A; Liss, T M; Lissauer, D; Lister, A; Litke, A M; Liu, C; Liu, D; Liu, H; Liu, J B; Liu, L; Liu, M; Liu, Y; Livan, M; Livermore, S S A; Lleres, A; Llorente Merino, J; Lloyd, S L; Lobodzinska, E; Loch, P; Lockman, W S; Loddenkoetter, T; Loebinger, F K; Loginov, A; Loh, C W; Lohse, T; Lohwasser, K; Lokajicek, M; Lombardo, V P; Long, R E; Lopes, L; Lopez Mateos, D; Lorenz, J; Lorenzo Martinez, N; Losada, M; Loscutoff, P; Lo Sterzo, F; Losty, M J; Lou, X; Lounis, A; Loureiro, K F; Love, J; Love, P A; Lowe, A J; Lu, F; Lubatti, H J; Luci, C; Lucotte, A; Ludwig, A; Ludwig, D; Ludwig, I; Ludwig, J; Luehring, F; Luijckx, G; Lukas, W; Lumb, D; Luminari, L; Lund, E; Lund-Jensen, B; Lundberg, B; Lundberg, J; Lundberg, O; Lundquist, J; Lungwitz, M; Lynn, D; Lytken, E; Ma, H; Ma, L L; Maccarrone, G; Macchiolo, A; Maček, B; Machado Miguens, J; Mackeprang, R; Madaras, R J; Maddocks, H J; Mader, W F; Maenner, R; Maeno, T; Mättig, P; Mättig, S; Magnoni, L; Magradze, E; Mahboubi, K; Mahlstedt, J; Mahmoud, S; Mahout, G; Maiani, C; Maidantchik, C; Maio, A; Majewski, S; Makida, Y; Makovec, N; Mal, P; Malaescu, B; Malecki, Pa; Malecki, P; Maleev, V P; Malek, F; Mallik, U; Malon, D; Malone, C; Maltezos, S; Malyshev, V; Malyukov, S; Mameghani, R; Mamuzic, J; Manabe, A; Mandelli, L; Mandić, I; Mandrysch, R; Maneira, J; Manfredini, A; Mangeard, P S; Manhaes de Andrade Filho, L; Manjarres Ramos, J A; Mann, A; Manning, P M; Manousakis-Katsikakis, A; Mansoulie, B; Mapelli, A; Mapelli, L; March, L; Marchand, J F; Marchese, F; Marchiori, G; Marcisovsky, M; Marino, C P; Marroquim, F; Marshall, Z; Martens, F K; Marti, L F; Marti-Garcia, S; Martin, B; Martin, B; Martin, J P; Martin, T A; Martin, V J; Martin Dit Latour, B; Martin-Haugh, S; Martinez, M; Martinez Outschoorn, V; Martyniuk, A C; Marx, M; Marzano, F; Marzin, A; Masetti, L; Mashimo, T; Mashinistov, R; Masik, J; Maslennikov, A L; Massa, I; Massaro, G; Massol, N; Mastrandrea, P; Mastroberardino, A; Masubuchi, T; Matricon, P; Matsunaga, H; Matsushita, T; Mattravers, C; Maurer, J; Maxfield, S J; Mayne, A; Mazini, R; Mazur, M; Mazzaferro, L; Mazzanti, M; Mc Donald, J; Mc Kee, S P; McCarn, A; McCarthy, R L; McCarthy, T G; McCubbin, N A; McFarlane, K W; McFayden, J A; McHedlidze, G; McLaughlan, T; McMahon, S J; McPherson, R A; Meade, A; Mechnich, J; Mechtel, M; Medinnis, M; Meera-Lebbai, R; Meguro, T; Mehdiyev, R; Mehlhase, S; Mehta, A; Meier, K; Meirose, B; Melachrinos, C; Mellado Garcia, B R; Meloni, F; Mendoza Navas, L; Meng, Z; Mengarelli, A; Menke, S; Meoni, E; Mercurio, K M; Mermod, P; Merola, L; Meroni, C; Merritt, F S; Merritt, H; Messina, A; Metcalfe, J; Mete, A S; Meyer, C; Meyer, C; Meyer, J-P; Meyer, J; Meyer, J; Meyer, T C; Miao, J; Michal, S; Micu, L; Middleton, R P; Migas, S; Mijović, L; Mikenberg, G; Mikestikova, M; Mikuž, M; Miller, D W; Miller, R J; Mills, W J; Mills, C; Milov, A; Milstead, D A; Milstein, D; Minaenko, A A; Miñano Moya, M; Minashvili, I A; Mincer, A I; Mindur, B; Mineev, M; Ming, Y; Mir, L M; Mirabelli, G; Mitrevski, J; Mitsou, V A; Mitsui, S; Miyagawa, P S; Mjörnmark, J U; Moa, T; Moeller, V; Mönig, K; Möser, N; Mohapatra, S; Mohr, W; Moles-Valls, R; Monk, J; Monnier, E; Montejo Berlingen, J; Monticelli, F; Monzani, S; Moore, R W; Moorhead, G F; Mora Herrera, C; Moraes, A; Morange, N; Morel, J; Morello, G; Moreno, D; Moreno Llácer, M; Morettini, P; Morgenstern, M; Morii, M; Morley, A K; Mornacchi, G; Morris, J D; Morvaj, L; Moser, H G; Mosidze, M; Moss, J; Mount, R; Mountricha, E; Mouraviev, S V; Moyse, E J W; Mueller, F; Mueller, J; Mueller, K; Müller, T A; Mueller, T; Muenstermann, D; Munwes, Y; Murray, W J; Mussche, I; Musto, E; Myagkov, A G; Myska, M; Nadal, J; Nagai, K; Nagai, R; Nagano, K; Nagarkar, A; Nagasaka, Y; Nagel, M; Nairz, A M; Nakahama, Y; Nakamura, K; Nakamura, T; Nakano, I; Nanava, G; Napier, A; Narayan, R; Nash, M; Nattermann, T; Naumann, T; Navarro, G; Neal, H A; Nechaeva, P Yu; Neep, T J; Negri, A; Negri, G; Negrini, M; Nektarijevic, S; Nelson, A; Nelson, T K; Nemecek, S; Nemethy, P; Nepomuceno, A A; Nessi, M; Neubauer, M S; Neumann, M; Neusiedl, A; Neves, R M; Nevski, P; Newman, P R; Nguyen Thi Hong, V; Nickerson, R B; Nicolaidou, R; Nicquevert, B; Niedercorn, F; Nielsen, J; Nikiforou, N; Nikiforov, A; Nikolaenko, V; Nikolic-Audit, I; Nikolics, K; Nikolopoulos, K; Nilsen, H; Nilsson, P; Ninomiya, Y; Nisati, A; Nisius, R; Nobe, T; Nodulman, L; Nomachi, M; Nomidis, I; Norberg, S; Nordberg, M; Norton, P R; Novakova, J; Nozaki, M; Nozka, L; Nugent, I M; Nuncio-Quiroz, A-E; Nunes Hanninger, G; Nunnemann, T; Nurse, E; O'Brien, B J; O'Neil, D C; O'Shea, V; Oakes, L B; Oakham, F G; Oberlack, H; Ocariz, J; Ochi, A; Oda, S; Odaka, S; Odier, J; Ogren, H; Oh, A; Oh, S H; Ohm, C C; Ohshima, T; Okawa, H; Okumura, Y; Okuyama, T; Olariu, A; Olchevski, A G; Olivares Pino, S A; Oliveira, M; Oliveira Damazio, D; Oliver Garcia, E; Olivito, D; Olszewski, A; Olszowska, J; Onofre, A; Onyisi, P U E; Oram, C J; Oreglia, M J; Oren, Y; Orestano, D; Orlando, N; Orlov, I; Oropeza Barrera, C; Orr, R S; Osculati, B; Ospanov, R; Osuna, C; Otero Y Garzon, G; Ottersbach, J P; Ouchrif, M; Ouellette, E A; Ould-Saada, F; Ouraou, A; Ouyang, Q; Ovcharova, A; Owen, M; Owen, S; Ozcan, V E; Ozturk, N; Pacheco Pages, A; Padilla Aranda, C; Pagan Griso, S; Paganis, E; Pahl, C; Paige, F; Pais, P; Pajchel, K; Palacino, G; Paleari, C P; Palestini, S; Pallin, D; Palma, A; Palmer, J D; Pan, Y B; Panagiotopoulou, E; Pani, P; Panikashvili, N; Panitkin, S; Pantea, D; Papadelis, A; Papadopoulou, Th D; Paramonov, A; Paredes Hernandez, D; Park, W; Parker, M A; Parodi, F; Parsons, J A; Parzefall, U; Pashapour, S; Pasqualucci, E; Passaggio, S; Passeri, A; Pastore, F; Pastore, Fr; Pásztor, G; Pataraia, S; Patel, N; Pater, J R; Patricelli, S; Pauly, T; Pecsy, M; Pedraza Lopez, S; Pedraza Morales, M I; Peleganchuk, S V; Pelikan, D; Peng, H; Penning, B; Penson, A; Penwell, J; Perantoni, M; Perez, K; Perez Cavalcanti, T; Perez Codina, E; Pérez García-Estañ, M T; Perez Reale, V; Perini, L; Pernegger, H; Perrino, R; Perrodo, P; Peshekhonov, V D; Peters, K; Petersen, B A; Petersen, J; Petersen, T C; Petit, E; Petridis, A; Petridou, C; Petrolo, E; Petrucci, F; Petschull, D; Petteni, M; Pezoa, R; Phan, A; Phillips, P W; Piacquadio, G; Picazio, A; Piccaro, E; Piccinini, M; Piec, S M; Piegaia, R; Pignotti, D T; Pilcher, J E; Pilkington, A D; Pina, J; Pinamonti, M; Pinder, A; Pinfold, J L; Pinto, B; Pizio, C; Plamondon, M; Pleier, M-A; Plotnikova, E; Poblaguev, A; Poddar, S; Podlyski, F; Poggioli, L; Pohl, D; Pohl, M; Polesello, G; Policicchio, A; Polini, A; Poll, J; Polychronakos, V; Pomeroy, D; Pommès, K; Pontecorvo, L; Pope, B G; Popeneciu, G A; Popovic, D S; Poppleton, A; Portell Bueso, X; Pospelov, G E; Pospisil, S; Potrap, I N; Potter, C J; Potter, C T; Poulard, G; Poveda, J; Pozdnyakov, V; Prabhu, R; Pralavorio, P; Pranko, A; Prasad, S; Pravahan, R; Prell, S; Pretzl, K; Price, D; Price, J; Price, L E; Prieur, D; Primavera, M; Prokofiev, K; Prokoshin, F; Protopopescu, S; Proudfoot, J; Prudent, X; Przybycien, M; Przysiezniak, H; Psoroulas, S; Ptacek, E; Pueschel, E; Purdham, J; Purohit, M; Puzo, P; Pylypchenko, Y; Qian, J; Quadt, A; Quarrie, D R; Quayle, W B; Quinonez, F; Raas, M; Radescu, V; Radloff, P; Rador, T; Ragusa, F; Rahal, G; Rahimi, A M; Rahm, D; Rajagopalan, S; Rammensee, M; Rammes, M; Randle-Conde, A S; Randrianarivony, K; Rauscher, F; Rave, T C; Raymond, M; Read, A L; Rebuzzi, D M; Redelbach, A; Redlinger, G; Reece, R; Reeves, K; Reinherz-Aronis, E; Reinsch, A; Reisinger, I; Rembser, C; Ren, Z L; Renaud, A; Rescigno, M; Resconi, S; Resende, B; Reznicek, P; Rezvani, R; Richter, R; Richter-Was, E; Ridel, M; Rijpstra, M; Rijssenbeek, M; Rimoldi, A; Rinaldi, L; Rios, R R; Riu, I; Rivoltella, G; Rizatdinova, F; Rizvi, E; Robertson, S H; Robichaud-Veronneau, A; Robinson, D; Robinson, J E M; Robson, A; Rocha de Lima, J G; Roda, C; Roda Dos Santos, D; Roe, A; Roe, S; Røhne, O; Rolli, S; Romaniouk, A; Romano, M; Romeo, G; Romero Adam, E; Rompotis, N; Roos, L; Ros, E; Rosati, S; Rosbach, K; Rose, A; Rose, M; Rosenbaum, G A; Rosenberg, E I; Rosendahl, P L; Rosenthal, O; Rosselet, L; Rossetti, V; Rossi, E; Rossi, L P; Rotaru, M; Roth, I; Rothberg, J; Rousseau, D; Royon, C R; Rozanov, A; Rozen, Y; Ruan, X; Rubbo, F; Rubinskiy, I; Ruckstuhl, N; Rud, V I; Rudolph, C; Rudolph, G; Rühr, F; Ruiz-Martinez, A; Rumyantsev, L; Rurikova, Z; Rusakovich, N A; Rutherfoord, J P; Ruwiedel, C; Ruzicka, P; Ryabov, Y F; Rybar, M; Rybkin, G; Ryder, N C; Saavedra, A F; Sadeh, I; Sadrozinski, H F-W; Sadykov, R; Safai Tehrani, F; Sakamoto, H; Salamanna, G; Salamon, A; Saleem, M; Salek, D; Salihagic, D; Salnikov, A; Salt, J; Salvachua Ferrando, B M; Salvatore, D; Salvatore, F; Salvucci, A; Salzburger, A; Sampsonidis, D; Samset, B H; Sanchez, A; Sanchez Martinez, V; Sandaker, H; Sander, H G; Sanders, M P; Sandhoff, M; Sandoval, T; Sandoval, C; Sandstroem, R; Sankey, D P C; Sansoni, A; Santamarina Rios, C; Santoni, C; Santonico, R; Santos, H; Saraiva, J G; Sarangi, T; Sarkisyan-Grinbaum, E; Sarri, F; Sartisohn, G; Sasaki, O; Sasaki, Y; Sasao, N; Satsounkevitch, I; Sauvage, G; Sauvan, E; Sauvan, J B; Savard, P; Savinov, V; Savu, D O; Sawyer, L; Saxon, D H; Saxon, J; Sbarra, C; Sbrizzi, A; Scannicchio, D A; Scarcella, M; Schaarschmidt, J; Schacht, P; Schaefer, D; Schäfer, U; Schaepe, S; Schaetzel, S; Schaffer, A C; Schaile, D; Schamberger, R D; Schamov, A G; Scharf, V; Schegelsky, V A; Scheirich, D; Schernau, M; Scherzer, M I; Schiavi, C; Schieck, J; Schioppa, M; Schlenker, S; Schmidt, E; Schmieden, K; Schmitt, C; Schmitt, S; Schmitz, M; Schneider, B; Schnoor, U; Schoening, A; Schorlemmer, A L S; Schott, M; Schouten, D; Schovancova, J; Schram, M; Schroeder, C; Schroer, N; Schultens, M J; Schultes, J; Schultz-Coulon, H-C; Schulz, H; Schumacher, M; Schumm, B A; Schune, Ph; Schwanenberger, C; Schwartzman, A; Schwegler, Ph; Schwemling, Ph; Schwienhorst, R; Schwierz, R; Schwindling, J; Schwindt, T; Schwoerer, M; Sciolla, G; Scott, W G; Searcy, J; Sedov, G; Sedykh, E; Seidel, S C; Seiden, A; Seifert, F; Seixas, J M; Sekhniaidze, G; Sekula, S J; Selbach, K E; Seliverstov, D M; Sellden, B; Sellers, G; Seman, M; Semprini-Cesari, N; Serfon, C; Serin, L; Serkin, L; Seuster, R; Severini, H; Sfyrla, A; Shabalina, E; Shamim, M; Shan, L Y; Shank, J T; Shao, Q T; Shapiro, M; Shatalov, P B; Shaw, K; Sherman, D; Sherwood, P; Shibata, A; Shimizu, S; Shimojima, M; Shin, T; Shiyakova, M; Shmeleva, A; Shochet, M J; Short, D; Shrestha, S; Shulga, E; Shupe, M A; Sicho, P; Sidoti, A; Siegert, F; Sijacki, Dj; Silbert, O; Silva, J; Silver, Y; Silverstein, D; Silverstein, S B; Simak, V; Simard, O; Simic, Lj; Simion, S; Simioni, E; Simmons, B; Simoniello, R; Simonyan, M; Sinervo, P; Sinev, N B; Sipica, V; Siragusa, G; Sircar, A; Sisakyan, A N; Sivoklokov, S Yu; Sjölin, J; Sjursen, T B; Skinnari, L A; Skottowe, H P; Skovpen, K; Skubic, P; Slater, M; Slavicek, T; Sliwa, K; Smakhtin, V; Smart, B H; Smestad, S L; Smirnov, S Yu; Smirnov, Y; Smirnova, L N; Smirnova, O; Smith, B C; Smith, D; Smith, K M; Smizanska, M; Smolek, K; Snesarev, A A; Snow, S W; Snow, J; Snyder, S; Sobie, R; Sodomka, J; Soffer, A; Solans, C A; Solar, M; Solc, J; Soldatov, E Yu; Soldevila, U; Solfaroli Camillocci, E; Solodkov, A A; Solovyanov, O V; Solovyev, V; Soni, N; Sopko, V; Sopko, B; Sosebee, M; Soualah, R; Soukharev, A; Spagnolo, S; Spanò, F; Spighi, R; Spigo, G; Spiwoks, R; Spousta, M; Spreitzer, T; Spurlock, B; St Denis, R D; Stahlman, J; Stamen, R; Stanecka, E; Stanek, R W; Stanescu, C; Stanescu-Bellu, M; Stanitzki, M M; Stapnes, S; Starchenko, E A; Stark, J; Staroba, P; Starovoitov, P; Staszewski, R; Staude, A; Stavina, P; Steele, G; Steinbach, P; Steinberg, P; Stekl, I; Stelzer, B; Stelzer, H J; Stelzer-Chilton, O; Stenzel, H; Stern, S; Stewart, G A; Stillings, J A; Stockton, M C; Stoerig, K; Stoicea, G; Stonjek, S; Strachota, P; Stradling, A R; Straessner, A; Strandberg, J; Strandberg, S; Strandlie, A; Strang, M; Strauss, E; Strauss, M; Strizenec, P; Ströhmer, R; Strom, D M; Strong, J A; Stroynowski, R; Strube, J; Stugu, B; Stumer, I; Stupak, J; Sturm, P; Styles, N A; Soh, D A; Su, D; Subramania, Hs; Succurro, A; Sugaya, Y; Suhr, C; Suk, M; Sulin, V V; Sultansoy, S; Sumida, T; Sun, X; Sundermann, J E; Suruliz, K; Susinno, G; Sutton, M R; Suzuki, Y; Suzuki, Y; Svatos, M; Swedish, S; Sykora, I; Sykora, T; Sánchez, J; Ta, D; Tackmann, K; Taffard, A; Tafirout, R; Taiblum, N; Takahashi, Y; Takai, H; Takashima, R; Takeda, H; Takeshita, T; Takubo, Y; Talby, M; Talyshev, A; Tamsett, M C; Tanaka, J; Tanaka, R; Tanaka, S; Tanaka, S; Tanasijczuk, A J; Tani, K; Tannoury, N; Tapprogge, S; Tardif, D; Tarem, S; Tarrade, F; Tartarelli, G F; Tas, P; Tasevsky, M; Tassi, E; Tatarkhanov, M; Tayalati, Y; Taylor, C; Taylor, F E; Taylor, G N; Taylor, W; Teinturier, M; Teischinger, F A; Teixeira Dias Castanheira, M; Teixeira-Dias, P; Temming, K K; Ten Kate, H; Teng, P K; Terada, S; Terashi, K; Terron, J; Testa, M; Teuscher, R J; Therhaag, J; Theveneaux-Pelzer, T; Thoma, S; Thomas, J P; Thompson, E N; Thompson, P D; Thompson, P D; Thompson, A S; Thomsen, L A; Thomson, E; Thomson, M; Thong, W M; Thun, R P; Tian, F; Tibbetts, M J; Tic, T; Tikhomirov, V O; Tikhonov, Y A; Timoshenko, S; Tipton, P; Tisserant, S; Todorov, T; Todorova-Nova, S; Toggerson, B; Tojo, J; Tokár, S; Tokushuku, K; Tollefson, K; Tomoto, M; Tompkins, L; Toms, K; Tonoyan, A; Topfel, C; Topilin, N D; Torchiani, I; Torrence, E; Torres, H; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Trefzger, T; Tremblet, L; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Tripiana, M F; Triplett, N; Trischuk, W; Trocmé, B; Troncon, C; Trottier-McDonald, M; Trzebinski, M; Trzupek, A; Tsarouchas, C; Tseng, J C-L; Tsiakiris, M; Tsiareshka, P V; Tsionou, D; Tsipolitis, G; Tsiskaridze, S; Tsiskaridze, V; Tskhadadze, E G; Tsukerman, I I; Tsulaia, V; Tsung, J-W; Tsuno, S; Tsybychev, D; Tua, A; Tudorache, A; Tudorache, V; Tuggle, J M; Turala, M; Turecek, D; Turk Cakir, I; Turlay, E; Turra, R; Tuts, P M; Tykhonov, A; Tylmad, M; Tyndel, M; Tzanakos, G; Uchida, K; Ueda, I; Ueno, R; Ugland, M; Uhlenbrock, M; Uhrmacher, M; Ukegawa, F; Unal, G; Undrus, A; Unel, G; Unno, Y; Urbaniec, D; Urquijo, P; Usai, G; Uslenghi, M; Vacavant, L; Vacek, V; Vachon, B; Vahsen, S; Valenta, J; Valentinetti, S; Valero, A; Valkar, S; Valladolid Gallego, E; Vallecorsa, S; Valls Ferrer, J A; Van Der Deijl, P C; van der Geer, R; van der Graaf, H; Van Der Leeuw, R; van der Poel, E; van der Ster, D; van Eldik, N; van Gemmeren, P; van Vulpen, I; Vanadia, M; Vandelli, W; Vaniachine, A; Vankov, P; Vannucci, F; Vari, R; Varol, T; Varouchas, D; Vartapetian, A; Varvell, K E; Vassilakopoulos, V I; Vazeille, F; Vazquez Schroeder, T; Vegni, G; Veillet, J J; Veloso, F; Veness, R; Veneziano, S; Ventura, A; Ventura, D; Venturi, M; Venturi, N; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, J C; Vest, A; Vetterli, M C; Vichou, I; Vickey, T; Vickey Boeriu, O E; Viehhauser, G H A; Viel, S; Villa, M; Villaplana Perez, M; Vilucchi, E; Vincter, M G; Vinek, E; Vinogradov, V B; Virchaux, M; Virzi, J; Vitells, O; Viti, M; Vivarelli, I; Vives Vaque, F; Vlachos, S; Vladoiu, D; Vlasak, M; Vogel, A; Vokac, P; Volpi, G; Volpi, M; Volpini, G; von der Schmitt, H; von Radziewski, H; von Toerne, E; Vorobel, V; Vorwerk, V; Vos, M; Voss, R; Voss, T T; Vossebeld, J H; Vranjes, N; Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vu Anh, T; Vuillermet, R; Vukotic, I; Wagner, W; Wagner, P; Wahlen, H; Wahrmund, S; Wakabayashi, J; Walch, S; Walder, J; Walker, R; Walkowiak, W; Wall, R; Waller, P; Walsh, B; Wang, C; Wang, H; Wang, H; Wang, J; Wang, J; Wang, R; Wang, S M; Wang, T; Warburton, A; Ward, C P; Warsinsky, M; Washbrook, A; Wasicki, C; Watanabe, I; Watkins, P M; Watson, A T; Watson, I J; Watson, M F; Watts, G; Watts, S; Waugh, A T; Waugh, B M; Weber, M S; Weber, P; Weidberg, A R; Weigell, P; Weingarten, J; Weiser, C; Wells, P S; Wenaus, T; Wendland, D; Weng, Z; Wengler, T; Wenig, S; Wermes, N; Werner, M; Werner, P; Werth, M; Wessels, M; Wetter, J; Weydert, C; Whalen, K; Wheeler-Ellis, S J; White, A; White, M J; White, S; Whitehead, S R; Whiteson, D; Whittington, D; Wicek, F; Wicke, D; Wickens, F J; Wiedenmann, W; Wielers, M; Wienemann, P; Wiglesworth, C; Wiik-Fuchs, L A M; Wijeratne, P A; Wildauer, A; Wildt, M A; Wilhelm, I; Wilkens, H G; Will, J Z; Williams, E; Williams, H H; Willis, W; Willocq, S; Wilson, J A; Wilson, M G; Wilson, A; Wingerter-Seez, I; Winkelmann, S; Winklmeier, F; Wittgen, M; Wollstadt, S J; Wolter, M W; Wolters, H; Wong, W C; Wooden, G; Wosiek, B K; Wotschack, J; Woudstra, M J; Wozniak, K W; Wraight, K; Wright, M; Wrona, B; Wu, S L; Wu, X; Wu, Y; Wulf, E; Wynne, B M; Xella, S; Xiao, M; Xie, S; Xu, C; Xu, D; Yabsley, B; Yacoob, S; Yamada, M; Yamaguchi, H; Yamamoto, A; Yamamoto, K; Yamamoto, S; Yamamura, T; Yamanaka, T; Yamaoka, J; Yamazaki, T; Yamazaki, Y; Yan, Z; Yang, H; Yang, U K; Yang, Y; Yang, Z; Yanush, S; Yao, L; Yao, Y; Yasu, Y; Ybeles Smit, G V; Ye, J; Ye, S; Yilmaz, M; Yoosoofmiya, R; Yorita, K; Yoshida, R; Young, C; Young, C J; Youssef, S; Yu, D; Yu, J; Yu, J; Yuan, L; Yurkewicz, A; Byszewski, M; Zabinski, B; Zaidan, R; Zaitsev, A M; Zajacova, Z; Zanello, L; Zanzi, D; Zaytsev, A; Zeitnitz, C; Zeman, M; Zemla, A; Zendler, C; Zenin, O; Zeniš, T; Zinonos, Z; Zenz, S; Zerwas, D; Zevi Della Porta, G; Zhan, Z; Zhang, D; Zhang, H; Zhang, J; Zhang, X; Zhang, Z; Zhao, L; Zhao, T; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, N; Zhou, Y; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhuravlov, V; Zieminska, D; Zimin, N I; Zimmermann, R; Zimmermann, S; Zimmermann, S; Ziolkowski, M; Zitoun, R; Zivković, L; Zmouchko, V V; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zutshi, V; Zwalinski, L

2012-11-21

A search for direct pair production of supersymmetric top squarks (t(1)) is presented, assuming the t(1) decays into a top quark and the lightest supersymmetric particle, χ(1)(0), and that both top quarks decay to purely hadronic final states. A total of 16 (4) events are observed compared to a predicted standard model background of 13.5(-3.6)(+3.7)(4.4(-1.3)(+1.7)) events in two signal regions based on ∫Ldt = 4.7 fb(-1) of pp collision data taken at sqrt[s] = 7 TeV with the ATLAS detector at the LHC. An exclusion region in the t(1) versus χ(1)(0) mass plane is evaluated: 370

A comparison of the reactivity of germylene and dimethylgermylene with some methylgermanes. Direct kinetic and quantum chemical studies.

PubMed

Becerra, Rosa; Boganov, Sergey E; Egorov, Mikhail P; Faustov, Valery I; Krylova, Irina V; Nefedov, Oleg M; Promyslov, Vladimir M; Walsh, Robin

2007-08-21

Time-resolved studies of germylene, GeH(2), and dimethygermylene, GeMe(2), generated by the 193 nm laser flash photolysis of appropriate precursor molecules have been carried out to try to obtain rate coefficients for their bimolecular reactions with dimethylgermane, Me(2)GeH(2), in the gas-phase. GeH(2) + Me(2)GeH(2) was studied over the pressure range 1-100 Torr with SF(6) as bath gas and at five temperatures in the range 296-553 K. Only slight pressure dependences were found (at 386, 447 and 553 K). RRKM modelling was carried out to fit these pressure dependences. The high pressure rate coefficients gave the Arrhenius parameters: log(A/cm(3) molecule(-1) s(-1)) = -10.99 +/- 0.07 and E(a) =-(7.35 +/- 0.48) kJ mol(-1). No reaction could be found between GeMe(2) + Me(2)GeH(2) at any temperature up to 549 K, and upper limits of ca. 10(-14) cm(3) molecule(-1) s(-1) were set for the rate coefficients. A rate coefficient of (1.33 +/- 0.04) x 10(-10) cm(3) molecule(-1) s(-1) was also obtained for GeH(2) + MeGeH(3) at 296 K. No reaction was found between GeMe(2) and MeGeH(3). Rate coefficient comparisons showed, inter alia, that in the substrate germane Me-for-H substitution increased the magnitudes of rate coefficients significantly, while in the germylene Me-for-H substitution decreased the magnitudes of rate coefficients by at least four orders of magnitude. Quantum chemical calculations (G2(MP2,SVP)//B3LYP level) supported these findings and showed that the lack of reactivity of GeMe(2) is caused by a positive energy barrier for rearrangement of the initially formed complexes. Full details of the structures of intermediate complexes and the discussion of their stabilities are given in the paper.

Comparison of cross-sectional transmission electron microscope studies of thin germanium epilayers grown on differently oriented silicon wafers.

PubMed

Norris, D J; Myronov, M; Leadley, D R; Walther, T

2017-12-01

We compare transmission electron microscopical analyses of the onset of islanding in the germanium-on-silicon (Ge/Si) system for three different Si substrate orientations: (001), (11¯0) and (11¯1)Si. The Ge was deposited by reduced pressure chemical vapour deposition and forms islands on the surface of all Si wafers; however, the morphology (aspect ratio) of the deposited islands is different for each type of wafer. Moreover, the mechanism for strain relaxation is different for each type of wafer owing to the different orientation of the (111) slip planes with the growth surface. Ge grown on (001)Si is initially pseudomorphically strained, yielding small, almost symmetrical islands of high aspect ratio (clusters or domes) on top interdiffused SiGe pedestals, without any evidence of plastic relaxation by dislocations, which would nucleate later-on when the islands might have coalesced and then the Matthews-Blakeslee limit is reached. For (11¯0)Si, islands are flatter and more asymmetric, and this is correlated with plastic relaxation of some islands by dislocations. In the case of growth on (11¯1)Si wafers, there is evidence of immediate strain relaxation taking place by numerous dislocations and also twinning. In the case of untwined film/substrate interfaces, Burgers circuits drawn around certain (amorphous-like) regions show a nonclosure with an edge-type a/4[1¯12] Burgers vector component visible in projection along [110]. Microtwins of multiples of half unit cells in thickness have been observed which occur at the growth interface between the Si(11¯1) buffer layer and the overlying Ge material. Models of the growth mechanisms to explain the interfacial configurations of each type of wafer are suggested. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

Non-linear vibrational response of Ge and SiC membranes

NASA Astrophysics Data System (ADS)

Zhou, L. Q.; Colston, G.; Pearce, M. J.; Prince, R. G.; Myronov, M.; Leadley, D. R.; Trushkevych, O.; Edwards, R. S.

2017-07-01

Characterisation of membranes produced for use as micro-electro-mechanical systems using vibrational techniques can give a measure of their behaviour and suitability for operation in different environments. Two membranes are studied here: germanium (Ge) and cubic silicon carbide (3C-SiC) on a silicon (Si) substrate. When driven at higher displacements, the membranes exhibit self-protecting behaviour. The resonant vibration amplitude is limited to a maximum value of around 10 nm, through dissipation of energy via higher harmonic vibrations. This is observed for both materials, despite their different Young's moduli and defect densities.

Low-energy yield spectroscopy determination of band offsets: application to the epitaxial Ge/Si(100) heterostructure

NASA Astrophysics Data System (ADS)

Di Gaspare, L.; Capellini, G.; Chudoba, C.; Sebastiani, M.; Evangelisti, F.

1996-09-01

We apply a new experimental method for determining band lineups at the Ge/Si(100) heterostructure. This method uses a modern version of an old spectroscopy: the photoelectric yield spectroscopy excited with photons in the near UV range. It is shown that both substrate and overlayer valence-band tops can be identified in the yield spectrum, thus allowing a direct and precise determination of the band lineup. We find an offset of 0.36 ± 0.02 eV for heterojunctions whose overlayers were grown according to the Stranski-Krastanov mechanism.

New adatom model for Si(11) 7X7 and Si(111)Ge 5X5 reconstructed surfaces

NASA Technical Reports Server (NTRS)

Chadi, D. J.

1985-01-01

A new adatom model differing from the conventional model by a reconstruction of the substrate is proposed. The new adatom structure provides an explanation for the 7x7 and 5x5 size of the unit cells seen on annealed Si(111) and Si(111)-Ge surfaces, respectively. The model is consistent with structural information from vacuum-tunneling microscopy. It also provides simple explanations for stacking-fault-type features expected from Rutherford backscattering experiments and for similarities in the LEED and photoemission spectra of 2x1 and 7x7 surfaces.

An evaluation of alloys and coatings for use in automobile thermal reactors

NASA Technical Reports Server (NTRS)

Blankenship, C. P.; Oldrieve, R. E.

1974-01-01

Several candidate alloys and coatings were evaluated for use in automobile thermal reactors. Full-size reactors of the candidate materials were analyzed in cyclic engine dynamometer tests with peak temperature of 1900 F (1040 C). Two developmental ferritic iron alloys GE1541 and NASA-18T - exhibited the best overall performance lasting at least 60% of the life of the test engine. Four of the alloys evaluated warrant consideration for reactor use. They include GE1541, Armco 18 SR, NASA-18T, and Inconel 601. None of the commercial coating substrate combinations evaluated warrant consideration for reactor use.-

Evaluation of alloys and coatings for use in automobile thermal reactors

NASA Technical Reports Server (NTRS)

Blankenship, C. P.; Oldrieve, R. E.

1974-01-01

Several candidate alloys and coatings were evaluated for use in automobile thermal reactors. Full-size reactors of the candidate materials were evaluated in cyclic engine dynamometer tests with a peak temperature of 1040 C (1900 F). Two developmental ferritic-iron alloys, GE-1541 and NASA-18T, exhibited the best overall performance by lasting at least 60 percent of the life of test engine. Four of the alloys evaluated warrant consideration for reactor use. They are GE-1541, Armco 18 SR, NASA-18T, and Inconel 601. None of the commercial coating substrate combinations evaluated warrant consideration for reactor use.

Advanced Solar Panel Designs

NASA Technical Reports Server (NTRS)

Ralph, E. L.; Linder, E. B.

1995-01-01

Solar panel designs that utilize new high-efficiency solar cells and lightweight rigid panel technologies are described. The resulting designs increase the specific power (W/kg) achievable in the near-term and are well suited to meet the demands of higher performance small satellites (smallsats). Advanced solar panel designs have been developed and demonstrated on two NASA SBIR contracts at Applied Solar. The first used 19% efficient, large area (5.5 cm x 6.5 cm) GaAs/Ge solar cells with a lightweight rigid graphite epoxy isogrid substrate configuration. A 1,445 sq cm coupon was fabricated and tested to demonstrate 60 W/kg with a high potential of achieving 80 W/kg. The second panel design used new 22% efficiency, dual-junction GaInP2/GaAs/Ge solar cells combined with a lightweight aluminum core/graphite fiber mesh facesheet substrate. A 1,445 sq cm coupon was fabricated and tested to demonstrate 105 W/kg with the potential of achieving 115 W/kg.

Device optimization and scaling properties of a gate-on-germanium source tunnel field-effect transistor

NASA Astrophysics Data System (ADS)

Chattopadhyay, Avik; Mallik, Abhijit; Omura, Yasuhisa

2015-06-01

A gate-on-germanium source (GoGeS) tunnel field-effect transistor (TFET) shows great promise for low-power (sub-0.5 V) applications. A detailed investigation, with the help of a numerical device simulator, on the effects of variation in different structural parameters of a GoGeS TFET on its electrical performance is reported in this paper. Structural parameters such as κ-value of the gate dielectric, length and κ-value of the spacer, and doping concentrations of both the substrate and source are considered. A low-κ symmetric spacer and a high-κ gate dielectric are found to yield better device performance. The substrate doping influences only the p-i-n leakage floor. The source doping is found to significantly affect performance parameters such as OFF-state current, ON-state current and subthreshold swing, in addition to a threshold voltage shift. Results of the investigation on the gate length scaling of such devices are also reported in this paper.

High Electron Mobility SiGe/Si Transistor Structures on Sapphire Substrates

NASA Technical Reports Server (NTRS)

Alterovitz, Samuel A.; Mueller, Carl H.; Croke, Edward T.; Ponchak, George E.

2004-01-01

SiGe/Si n-type modulation doped field effect structures and transistors (n-MODFETs) have been fabricated on r-plane sapphire substrates. The structures were deposited using molecular beam epitaxy, and antimony dopants were incorporated via a delta doping process. Secondary ion mass spectroscopy (SIMS) indicates that the peak antimony concentration was approximately 4 x 10(exp 19) per cubic centimeter. At these two temperatures, the electron carrier densities were 1.6 and 1.33 x 10(exp 12) per square centimeter, thus demonstrating that carrier confinement was excellent. Shubnikov-de Haas oscillations were observed at 0.25 K, thus confirming the two-dimensional nature of the carriers. Transistors, with gate lengths varying from 1 micron to 5 microns, were fabricated using these structures and dc characterization was performed at room temperature. The saturated drain current region extended over a wide source-to-drain voltage (V (sub DS)) range, with V (sub DS) knee voltages of approximately 0.5 V and increased leakage starting at voltages slightly higher than 4 V.

Semiconductor Nanomembrane Tubes: Three-Dimensional Confinement for Controlled Neurite Outgrowth

PubMed Central

Yu, Minrui; Huang, Yu; Ballweg, Jason; Shin, Hyuncheol; Huang, Minghuang; Savage, Donald E.; Lagally, Max G.; Dent, Erik W.; Blick, Robert H.; Williams, Justin C.

2013-01-01

In many neural culture studies, neurite migration on a flat, open surface does not reflect the three-dimensional (3D) microenvironment in vivo. With that in mind, we fabricated arrays of semiconductor tubes using strained silicon (Si) and germanium (Ge) nanomembranes and employed them as a cell culture substrate for primary cortical neurons. Our experiments show that the SiGe substrate and the tube fabrication process are biologically viable for neuron cells. We also observe that neurons are attracted by the tube topography, even in the absence of adhesion factors, and can be guided to pass through the tubes during outgrowth. Coupled with selective seeding of individual neurons close to the tube opening, growth within a tube can be limited to a single axon. Furthermore, the tube feature resembles the natural myelin, both physically and electrically, and it is possible to control the tube diameter to be close to that of an axon, providing a confined 3D contact with the axon membrane and potentially insulating it from the extracellular solution. PMID:21366271

Searches for a heavy scalar boson $$ \\mathrm{H} $$ decaying to a pair of 125 GeV Higgs bosons $$ \\mathrm{ hh } $$ or for a heavy pseudoscalar boson $$ \\mathrm{A} $$ decaying to $$ \\mathrm{Zh} $$, in the final states with $$\\mathrm{h} \\to \\tau \\tau$$

DOE PAGES

Khachatryan, Vardan

2016-02-09

A search for a heavy scalar boson H decaying into a pair of lighter standard-model-like 125 GeV Higgs bosons hh and a search for a heavy pseudoscalar boson A decaying into a Z and an h boson are presented. The searches are performed on a data set corresponding to an integrated luminosity of 19.7 fb -1 of pp collision data at a centre-of-mass energy of 8 TeV, collected by CMS in 2012. A final state consisting of two τ leptons and two b jets is used to search for the H → hh decay. A final state consisting of twomore » τ leptons from the h boson decay, and two additional leptons from the Z boson decay, is used to search for the decay A → Zh. The results are interpreted in the context of two-Higgs-doublet models. No excess is found above the standard model expectation and upper limits are set on the heavy boson production cross sections in the mass ranges 260 < m H < 350 GeV and 220 < m A < 350 GeV.« less

Temperature-dependent interface characteristic of silicon wafer bonding based on an amorphous germanium layer deposited by DC-magnetron sputtering

NASA Astrophysics Data System (ADS)

Ke, Shaoying; Lin, Shaoming; Ye, Yujie; Mao, Danfeng; Huang, Wei; Xu, Jianfang; Li, Cheng; Chen, Songyan

2018-03-01

We report a near-bubble-free low-temperature silicon (Si) wafer bonding with a thin amorphous Ge (a-Ge) intermediate layer. The DC-magnetron-sputtered a-Ge film on Si is demonstrated to be extremely flat (RMS = 0.28 nm) and hydrophilic (contact angle = 3°). The effect of the post-annealing temperature on the surface morphology and crystallinity of a-Ge film at the bonded interface is systematically identified. The relationship among the bubble density, annealing temperature, and crystallinity of a-Ge film is also clearly clarified. The crystallization of a-Ge film firstly appears at the bubble region. More interesting feature is that the crystallization starts from the center of the bubbles and sprawls to the bubble edge gradually. The H2 by-product is finally absorbed by intermediate Ge layer with crystalline phase after post annealing. Moreover, the whole a-Ge film out of the bubble totally crystallizes when the annealing time increases. This Ge integration at the bubble region leads to the decrease of the bubble density, which in turn increases the bonding strength.

Determination of the proton spin structure functions for 0.05 < Q 2 < 5 GeV 2 using CLAS

DOE PAGES

Fersch, R. G.; Guler, N.; Bosted, P.; ...

2017-12-27

In this work, we present the results of our final analysis of the full data set of gmore » $$p\\atop{1}$$ (Q 2), the spin structure function of the proton, collected using CLAS at Jefferson Laboratory in 2000–2001. Polarized electrons with energies of 1.6, 2.5, 4.2, and 5.7 GeV were scattered from proton targets ( 15NH 3 dynamically polarized along the beam direction) and detected with CLAS. From the measured double spin asymmetries, we extracted virtual photon asymmetries A$$p\\atop{1}$$ and A$$p\\atop{2}$$ and spin structure functions g$$p\\atop{1}$$ and g$$p\\atop{2}$$ over a wide kinematic range (0.05 GeV 2 < Q 2 < 5 GeV 2 and 1.08 GeV < W < 3 GeV) and calculated moments of g$$p\\atop{1}$$. We compare our final results with various theoretical models and expectations, as well as with parametrizations of the world data. Lastly, our data, with their precision and dense kinematic coverage, are able to constrain fits of polarized parton distributions, test pQCD predictions for quark polarizations at large x, offer a better understanding of quark-hadron duality, and provide more precise values of higher twist matrix elements in the framework of the operator product expansion.« less

Study of Sn and Mg doping effects on TiO2/Ge stack structure by combinatorial synthesis

NASA Astrophysics Data System (ADS)

Nagata, Takahiro; Suzuki, Yoshihisa; Yamashita, Yoshiyuki; Ogura, Atsushi; Chikyow, Toyohiro

2018-04-01

The effects of Sn and Mg doping of a TiO2 film on a Ge substrate were investigated to improve leakage current properties and Ge diffusion into the TiO2 film. For systematic analysis, dopant-composition-spread TiO2 samples with dopant concentrations of up to 20.0 at. % were fabricated by RF sputtering and a combinatorial method. X-ray photoelectron spectroscopy revealed that the instability of Mg doping of TiO2 at dopant concentrations above 10.5 at. %. Both Sn and Mg dopants reduced Ge diffusion into TiO2. Sn doping enhanced the crystallization of the rutile phase, which is a high-dielectric-constant phase, although the Mg-doped TiO2 film indicated an amorphous structure. Sn-doping indicated systematic leakage current reduction with increasing dopant concentration. Doping at Sn concentrations higher than 16.8 at. % improved the leakage properties (˜10-7 A/cm2 at -3.0 V) and capacitance-voltage properties of metal-insulator-semiconductor (MIS) operation. The Sn doping of TiO2 may be useful for interface control and as a dielectric material for Ge-based MIS capacitors.

n-type dopants in (001) β-Ga2O3 grown on (001) β-Ga2O3 substrates by plasma-assisted molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Han, Sang-Heon; Mauze, Akhil; Ahmadi, Elaheh; Mates, Tom; Oshima, Yuichi; Speck, James S.

2018-04-01

Ge and Sn as n-type dopants in (001) β-Ga2O3 films were investigated using plasma-assisted molecular beam epitaxy. The Ge concentration showed a strong dependence on the growth temperature, whereas the Sn concentration remains independent of the growth temperature. The maximum growth temperature at which a wide range of Ge concentrations (from 1017 to 1020 cm-3) could be achieved was 675 °C while the same range of Sn concentration could be achieved at growth temperature of 750 °C. Atomic force microscopy results revealed that higher growth temperature shows better surface morphology. Therefore, our study reveals a tradeoff between higher Ge doping concentration and high quality surface morphology on (001) β-Ga2O3 films grown by plasma-assisted molecular beam epitaxy. The Ge doped films had an electron mobility of 26.3 cm2 V-1 s-1 at the electron concentration of 6.7 × 1017 cm-3 whereas the Sn doped films had an electron mobility of 25.3 cm2 V-1 s-1 at the electron concentration of 1.1 × 1018 cm-3.

β-Glucuronidase-coupled assays of glucuronoyl esterases.

PubMed

Fraňová, Lucia; Puchart, Vladimír; Biely, Peter

2016-10-01

Glucuronoyl esterases (GEs) are microbial enzymes with potential to cleave the ester bonds between lignin alcohols and xylan-bound 4-O-methyl-d-glucuronic acid in plant cell walls. This activity renders GEs attractive research targets for biotechnological applications. One of the factors impeding the progress in GE research is the lack of suitable substrates. In this work, we report a facile preparation of methyl esters of chromogenic 4-nitrophenyl and 5-bromo-4-chloro-3-indolyl β-D-glucuronides for qualitative and quantitative GE assay coupled with β-glucuronidase as the auxiliary enzyme. The indolyl derivative affording a blue indigo-type product is suitable for rapid and sensitive assay of GE in commercial preparations as well as for high throughput screening of microorganisms and genomic and metagenomic libraries. Copyright © 2016 Elsevier Inc. All rights reserved.

Electronic properties of single Ge/Si quantum dot grown by ion beam sputtering deposition.

PubMed

Wang, C; Ke, S Y; Yang, J; Hu, W D; Qiu, F; Wang, R F; Yang, Y

2015-03-13

The dependence of the electronic properties of a single Ge/Si quantum dot (QD) grown by the ion-beam sputtering deposition technique on growth temperature and QD diameter is investigated by conductive atomic force microscopy (CAFM). The Si-Ge intermixing effect is demonstrated to be important for the current distribution of single QDs. The current staircase induced by the Coulomb blockade effect is observed at higher growth temperatures (>700 °C) due to the formation of an additional barrier between dislocated QDs and Si substrate for the resonant tunneling of holes. According to the proposed single-hole-tunneling model, the fact that the intermixing effect is observed to increase as the incoherent QD size decreases may explain the increase in the starting voltage of the current staircase and the decrease in the current step width.

Influence of Si interdiffusion on carbon-induced growth of Ge quantum dots: a strategy for tuning island density.

PubMed

Bernardi, A; Ossó, J O; Alonso, M I; Goñi, A R; Garriga, M

2006-05-28

We have studied the epitaxial growth of self-assembled Ge quantum dots when a submonolayer of carbon is deposited on a Ge wetting layer (WL) prior to the growth of the dots. Using atomic-force microscopy combined with optical techniques like Raman and ellipsometry, we performed a systematic study of the role played by thermally activated Si interdiffusion on dot density, composition and morphology, by changing only the growth temperature T(WL) of the WL. Strikingly, we observe that higher dot densities and a narrower size distribution are achieved by increasing the deposition temperature T(WL), i.e. by enhancing Si interdiffusion from the substrate. We suggest a two-stage growth procedure for fine tuning of dot topography (density, shape and size) useful for possible optoelectronic applications.

Effect of a Stepped Si(100) Surface on the Nucleation Process of Ge Islands

NASA Astrophysics Data System (ADS)

Yesin, M. Yu.; Nikiforov, A. I.; Timofeev, V. A.; Mashanov, V. I.; Tuktamyshev, A. R.; Loshkarev, I. D.; Pchelyakov, O. P.

2018-03-01

Nucleation of Ge islands on a stepped Si(100) surface is studied. It is shown by diffraction of fast electrons that at a temperature of 600°C, constant flux of Si, and deposition rate of 0.652 Å/s, a series of the 1×2 superstructure reflections completely disappears, if the Si (100) substrate deviated by an angle of 0.35° to the (111) face is preliminarily heated to 1000°C. The disappearance of the 1×2 superstructure reflexes is due to the transition from the surface with monoatomic steps to that with diatomic ones. Investigations of the Ge islands' growth were carried out on the Si(100) surface preliminarily annealed at temperatures of 800 and 1000°C. It is shown that the islands tend to nucleate at the step edges.

X-ray computed tomography for virtually unrolling damaged papyri

NASA Astrophysics Data System (ADS)

Allegra, Dario; Ciliberto, Enrico; Ciliberto, Paolo; Petrillo, Giuseppe; Stanco, Filippo; Trombatore, Claudia

2016-03-01

The regular format for ancient works of literature was the papyrus roll. Recently many efforts to perform virtual restoration of this archeological artifact have been done. In fact the case of ancient rolled papyrus is very intriguing. Old papyruses are the substrates of very important historical information, probably being the use of papyrus dated to the Pre-Dynastic Period. Papyrus degradation is often very hard so that physical unrolling is sometime absolutely impossible. In this paper, authors describe their effort in setting a new virtual restoration methodology based on software manipulation of X-ray tomographic images. A realistic model, obtained by painting a hieroglyph inscription of Thutmosis III on a papyrus substrate made by the original method described by Plinius the Elder and by pigments and binders compatible with the Egyptian use (ochers with natural glue), was made for the X-ray investigation. A GE Optima 660 64 slice was used to obtain a stack of tomographic slices of the rolled model. Each slice appears as spiral. The intensity variations along the cross-sectional result from ink on the papyrus. The files were elaborated with original software, written by the use of MATLAB high-level language, and the final result was quite similar to the radiography of the physically unrolled sheet.

Geraniol dehydrogenase, the key enzyme in biosynthesis of the alarm pheromone, from the astigmatid mite Carpoglyphus lactis (Acari: Carpoglyphidae).

PubMed

Noge, Koji; Kato, Makiko; Mori, Naoki; Kataoka, Michihiko; Tanaka, Chihiro; Yamasue, Yuji; Nishida, Ritsuo; Kuwahara, Yasumasa

2008-06-01

Geraniol dehydrogenase (GeDH), which plays an important role in the biosynthesis of neral, an alarm pheromone, was purified from the astigmatid mite Carpoglyphus lactis. The enzyme was obtained in an apparently homogeneous and active form after 1879-fold purification through seven steps of chromatography. Car. lactis GeDH was determined to be a monomer in its active form with a relative molecular mass of 42 800, which is a unique subunit structure in comparison with already established alcohol dehydrogenases. Car. lactis GeDH oxidized geraniol into geranial in the presence of NAD+. NADP+ was ineffective as a cofactor, suggesting that Car. lactis GeDH is an NAD+-dependent alcohol dehydrogenase. The optimal pH and temperature for geraniol oxidation were determined to be pH 9.0 and 25 degrees C, respectively. The Km values for geraniol and NAD+ were 51.0 microm and 59.5 microm, respectively. Car. lactis GeDH was shown to selectively oxidize geraniol, whereas its geometrical isomer, nerol, was inert as a substrate. The high specificity for geraniol suggests that Car. lactis GeDH specializes in the alarm pheromone biosynthesis of Car. lactis. Car. lactis GeDH is composed of 378 amino acids. Structurally, Car. lactis GeDH showed homology with zinc-dependent alcohol dehydrogenases found in mammals and a mosquito (36.6-37.6% identical), and the enzyme was considered to be a member of the medium-chain dehydrogenase/reductase family, in view of the highly conserved sequences of zinc-binding and NAD+-binding sites. Phylogenetic analyses indicate that Car. lactis GeDH could be categorized as a new class, different from other established alcohol dehydrogenases.

Foetal exposure to Panax ginseng extract reverts the effects of prenatal dexamethasone in the synthesis of testosterone by Leydig cells of the adult rat.

PubMed

Wanderley, Maria I; Saraiva, Karina L A; César Vieira, Juliany S B; Peixoto, Christina A; Udrisar, Daniel P

2013-06-01

The aim of this study was to examine the effect of maternal exposure to Panax ginseng extract (GE) on the prenatal dexamethasone (DEXA)-induced increase in testosterone production by isolated Leydig cells in adult rats. Pregnant rats were treated with (i) GE (200 mg/kg) or vehicle on days 10-21; (ii) DEXA (100 μg/kg) or vehicle on days 14-21; or (iii) a combination of GE plus DEXA at the same doses and with the same regimen. Testosterone production was induced either by the activator of protein kinase A (dbcAMP) or substrates of steroidogenesis [22(R)-hydroxycholesterol (22(R)-OH-C)] and pregnenolone. The capacity of rat Leydig cells exposed to DEXA to synthesize testosterone induced by dbcAMP, 22(R)-OH-C or pregnenolone was increased in comparison with the control group. Combined exposure to DEXA + GE prevented the effect of DEXA on the responsiveness of Leydig cells to all inductors of testosterone synthesis, whereas GE alone did not modify the response to inductors. No modifications in testosterone production were observed under basal conditions. StAR immunoexpression in Leydig cells was not modified by prenatal exposure to DEXA, GE or DEXA + GE. P450scc and glucocorticoid receptor immunoexpression was higher in offspring exposed to DEXA in comparison with the control group. This increased expression was prevented by combined treatment with DEXA + GE. The present findings demonstrate that GE is capable of reversing the effect of DEXA on testosterone synthesis by rat Leydig cells. © 2013 The Authors. International Journal of Experimental Pathology © 2013 International Journal of Experimental Pathology.

Hafnium silicate and hafnium silicon oxynitride gate dielectrics for strained Si_xGe_1-x: Interface stability

NASA Astrophysics Data System (ADS)

Addepalli, Swarna; Sivasubramani, Prasanna; El-Bouanani, Mohamed; Kim, Moon; Gnade, Bruce; Wallace, Robert

2003-03-01

Strained Si_xGe_1-x layers have gained considerable attention due to hole mobility enhancement, and ease of integration with Si-based CMOS technology. The deposition of stable high-κ dielectrics [1] such as hafnium silicate and hafnium silicon oxynitride in direct contact with SiGe would simultaneously improve the capacitance of the gate stack and lower the leakage current for high performance SiGe devices. However, the oxidation of the Si_xGe_1-x substrate either during dielectric deposition or post-deposition processing would degrade device performance due to the thermodynamic instability of germanium oxide [2,3]. Results from XPS, HR-TEM, and C-V, and I-V analyses after various annealing treatments will be presented for hafnium silicate and hafnium silicon oxynitride films deposited on strained Si_xGe_1-x(100), and correlated with dielectric-Si_xGe_1-x(100) interface stability. Implications to the introduction of these oxides as viable gate dielectric candidates for SiGe-based CMOS technology will be discussed. This work is supported by DARPA through SPAWAR Grant No. N66001-00-1-8928, and the Texas Advanced Technology Program. References: [1] G. D. Wilk, R. M. Wallace and J. M. Anthony, Journal of Applied Physics, 89, 5243 (2001) [2] W. S. Liu, J .S. Chen, M.-A. Nicolet, V. Arbet-Engels, K. L. Wang, Journal of Applied Physics, 72, 4444 (1992), and, Applied Physics Letters, 62, 3321 (1993) [3] W. S. Liu, M. -A. Nicolet, H. -H. Park, B. -H. Koak, J. -W. Lee, Journal of Applied Physics, 78, 2631 (1995)

Effect of different surface treatments on adhesion of In-Ceram Zirconia to enamel and dentin substrates.

PubMed

Saker, Samah; Ibrahim, Fatma; Ozcan, Mutlu

2013-08-01

Resin bonding of In-Ceram Zirconia (ICZ) ceramics is still a challenge, especially for minimally invasive applications. This study evaluated the adhesion of ICZ to enamel and dentin after different surface treatments of the ceramic. ICZ ceramic specimens (diameter: 6 mm; thickness: 2 mm) (N = 100) were fabricated following the manufacturer's instructions and randomly assigned to 5 groups (n = 20), according to the surface treatment methods applied. The groups were as follows: group C: no treatment; group SB: sandblasting; group SCS-S: CoJet+silane; group SCS-P: CoJet+Alloy Primer; group GE-S: glaze+ hydrofluoric acid etching (9.6%) for 60 s+silane. Each group was randomly divided into two subgroups to be bonded to either enamel or dentin (n = 10 per group) using MDP-based resin cement (Panavia F2.0). All the specimens were subjected to thermocycling (5000x, 5°C-55°C). The specimens were mounted in a universal testing machine and tensile force was applied to the ceramic/cement interface until failure occurred (1 mm/min). After evaluating all the debonded specimens under SEM, the failure types were defined as either "adhesive" with no cement left on the ceramic surface (score 0) or "mixed" with less than 1/2 of the cement left adhered to the surface with no cohesive failure of the substrate (score 1). The data were statistically evaluated using 2-way ANOVA and Tukey's tests (α = 0.05). The highest tensile bond strength for the enamel surfaces was obtained in group GE-S (18.1 ± 2 MPa) and the lowest in group SB (7.1 ± 1.4 MPa). Regarding dentin, group CSC-P showed the highest (12 ± 1.3 MPa) and SB the lowest tensile bond strength (5.7 ± 0.4 MPa). Groups SB, CSC-S, CSC-P, and GE-S did not show significant differences between the different surface treatments on either enamel or dentin surfaces (p < 0.05, p < 0.001, respectively). Groups CSC-P and GE-S presented similar bond strength for both the enamel and dentin substrates (p < 0.8 and p < 0.9), respectively. While on enamel substrates, exclusively adhesive failures from ICZ (score 0) were found, on dentin exclusively mixed failures were observed (score 1). Adhesion of ICZ to both enamel and dentin can be improved when ceramics are glazed, etched, and silanized, or sandblasted, primed, and cemented with an MDP-based cement.

Single layer of Ge quantum dots in HfO2 for floating gate memory capacitors.

PubMed

Lepadatu, A M; Palade, C; Slav, A; Maraloiu, A V; Lazanu, S; Stoica, T; Logofatu, C; Teodorescu, V S; Ciurea, M L

2017-04-28

High performance trilayer memory capacitors with a floating gate of a single layer of Ge quantum dots (QDs) in HfO 2 were fabricated using magnetron sputtering followed by rapid thermal annealing (RTA). The layer sequence of the capacitors is gate HfO 2 /floating gate of single layer of Ge QDs in HfO 2 /tunnel HfO 2 /p-Si wafers. Both Ge and HfO 2 are nanostructured by RTA at moderate temperatures of 600-700 °C. By nanostructuring at 600 °C, the formation of a single layer of well separated Ge QDs with diameters of 2-3 nm at a density of 4-5 × 10 15 m -2 is achieved in the floating gate (intermediate layer). The Ge QDs inside the intermediate layer are arranged in a single layer and are separated from each other by HfO 2 nanocrystals (NCs) about 8 nm in diameter with a tetragonal/orthorhombic structure. The Ge QDs in the single layer are located at the crossing of the HfO 2 NCs boundaries. In the intermediate layer, besides Ge QDs, a part of the Ge atoms is segregated by RTA at the HfO 2 NCs boundaries, while another part of the Ge atoms is present inside the HfO 2 lattice stabilizing the tetragonal/orthorhombic structure. The fabricated capacitors show a memory window of 3.8 ± 0.5 V and a capacitance-time characteristic with 14% capacitance decay in the first 3000-4000 s followed by a very slow capacitance decrease extrapolated to 50% after 10 years. This high performance is mainly due to the floating gate of a single layer of well separated Ge QDs in HfO 2 , distanced from the Si substrate by the tunnel oxide layer with a precise thickness.

One-Pot Synthesis of GeAs Ultrafine Particles from Coal Fly Ash by Vacuum Dynamic Flash Reduction and Inert Gas Condensation.

PubMed

Zhang, Lingen; Xu, Zhenming

2017-06-16

Ge-monopnictides (GeAs) plays critical role in high-tech industry, especially in the field of advanced optical devices and infrared. As a secondary material, coal fly ash could be further recycled to retrieve germanium and prepare GeAs material with high added values. Hence, the aim of this paper is to propose a one-pot synthesis that uses vacuum flash reduction and inert-gas consolidation method to prepare GeAs ultrafine particles. Germanium in coal fly ash can be successfully recycled; simultaneously, GeAs ultrafine particles were prepared. Separation principle and feasibility of this process was discussed. Temperature, carrier gas flow rate and system pressure were the major factors on formation, morphology and distribution of particle size of GeAs ultrafine particles. A three steps synthetic mechanism was clarified, namely, thermal rupture of coal fly ash and release of GeO 2 and As 2 O 3 , the gas-solid phase reaction of GeO 2 , As 2 O 3 and coke to generate metallic Ge and As in vacuum flash reduction. Meantime, GeAs were produced in the gas phase reaction. Finally, GeAs ultrafine particles were obtained by carrier gas condensation. In short, this research developed a practical and environment-friendly one-pot synthesis to recycle germanium in coal fly ash and prepare GeAs ultrafine particles with high added values.

Germanium Nanowires-in-Graphite Tubes via Self-Catalyzed Synergetic Confined Growth and Shell-Splitting Enhanced Li-Storage Performance.

PubMed

Sun, Yong; Jin, Shuaixing; Yang, Guowei; Wang, Jing; Wang, Chengxin

2015-04-28

Despite the high theoretical capacity, pure Ge has various difficulties such as significant volume expansion and electron and Li(+) transfer problems, when applied as anode materials in lithium ion battery (LIB), for which the solution would finally rely on rational design like advanced structures and available hybrid. Here in this work, we report a one-step synthesis of Ge nanowires-in-graphite tubes (GNIGTs) with the liquid Ge/C synergetic confined growth method. The structure exhibits impressing LIB behavior in terms of both cyclic stability and rate performance. We found the semiclosed graphite shell with thickness of ∼50 layers experience an interesting splitting process that was driven by electrolyte diffusion, which occurs before the Ge-Li alloying plateau begins. Two types of different splitting mechanism addressed as "inside-out"/zipper effect and "outside-in" dominate this process, which are resulted from the SEI layer growing longitudinally along the Ge-graphite interface and the lateral diffusion of Li(+) across the shell, respectively. The former mechanism is the predominant way driving the initial shell to split, which behaves like a zipper with SEI layer as invisible puller. After repeated Li(+) insertion/exaction, the GNIGTs configuration is finally reconstructed by forming Ge nanowires-thin graphite strip hybrid, both of which are in close contact, resulting in enormous enchantment to the electrons/Li(+) transport. These features make the structures perform well as anode material in LIB. We believe both the progress in 1D assembly and the structure evolution of this Ge-C composite would contribute to the design of advanced LIB anode materials.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alkhaldi, H. S.; Department of Physics in Jubail Education college, Dammam University, Dammam 1982; Kremer, F.

The development of porosity in single-crystal germanium and silicon-germanium alloys (c-Si{sub 1−x} Ge{sub x}) of (100) orientation was studied under bombardment with 140 keV Ge{sup −} ions over a wide range of temperatures (−180 to 400 °C) and ion fluences up to 1 × 10{sup 18} ions/cm{sup 2}. The surface swelling and morphology were investigated using multi-characterization techniques including optical profilometry, transmission electron microscopy, and scanning electron microscopy. The initiation of porosity and the evolution of the near-surface microstructure strongly depend on the ion fluence, the irradiation temperature, and the stoichiometry of the substrate. Significant results and new findings include: (i) the fact that,more » over the entire temperature and stoichiometry range, porosity is only developed once the substrate is rendered amorphous; (ii) with increasing Si content in the alloy, the onset of porosity is pushed to higher fluences; (iii) porosity is observed for Si contents in the alloy up to 23% but not higher under the irradiation conditions used; and (iv) in all cases the initiation of porosity was observed to occur at the surface of the amorphous alloy above a threshold fluence. This last result strongly suggests that the mechanism for initiation of porosity is via preferential vacancy segregation and clustering at the surface of the amorphous alloy. Particularly at elevated temperatures, preferential sputtering of the Si-Ge atomic species in the alloy also plays an important role in developing the surface topography and porosity in alloys. Such effects are discussed along with the implications of our results for mechanisms of porosity in Ge and its alloys.« less

Bright photoluminescence from ordered arrays of SiGe nanowires grown on Si(111)

PubMed Central

Rowell, N L; Benkouider, A; Ronda, A; Favre, L; Berbezier, I

2014-01-01

Summary We report on the optical properties of SiGe nanowires (NWs) grown by molecular beam epitaxy (MBE) in ordered arrays on SiO2/Si(111) substrates. The production method employs Au catalysts with self-limited sizes deposited in SiO2-free sites opened-up in the substrate by focused ion beam patterning for the preferential nucleation and growth of these well-organized NWs. The NWs thus produced have a diameter of 200 nm, a length of 200 nm, and a Ge concentration x = 0.15. Their photoluminescence (PL) spectra were measured at low temperatures (from 6 to 25 K) with excitation at 405 and 458 nm. There are four major features in the energy range of interest (980–1120 meV) at energies of 1040.7, 1082.8, 1092.5, and 1098.5 meV, which are assigned to the NW-transverse optic (TO) Si–Si mode, NW-transverse acoustic (TA), Si–substrate–TO and NW-no-phonon (NP) lines, respectively. From these results the NW TA and TO phonon energies are found to be 15.7 and 57.8 meV, respectively, which agree very well with the values expected for bulk Si1− xGex with x = 0.15, while the measured NW NP energy of 1099 meV would indicate a bulk-like Ge concentration of x = 0.14. Both of these concentrations values, as determined from PL, are in agreement with the target value. The NWs are too large in diameter for a quantum confinement induced energy shift in the band gap. Nevertheless, NW PL is readily observed, indicating that efficient carrier recombination is occurring within the NWs. PMID:25671145

Gallium Arsenide welded panel technology for advanced spaceflight applications

NASA Technical Reports Server (NTRS)

Lillington, D. R.; Gillanders, M. S.; Garlick, G. F. J.; Cavicchi, B. T.; Glenn, G. S.; Tobin, S. P.

1989-01-01

A significant impediment to the widespread use of GaAs solar cells in space is the cost and weight of the GaAs substrate. In order to overcome these problems, Spectrolab is pursuing thin cell technologies encompassing both liquid phase epitaxy (LPE) GaAs on GaAs and MOCVD GaAs on Ge cells. Spectrolab's experience in the manufacture of 4 to 6 mil 2 cm x 4 cm GaAs cells on a LPE production line is discussed. By thinning the cells at a late state of processing, production yields comparable to 12 mil cells have been achieved. Data are presented showing that GaAs cells can be welded without degradation and have achieved minimum average efficiencies of 18 percent AM0, 28 C with efficiencies up to 20 percent. Spectrolab, in conjunction with Spire Corporation has also been pursuing GaAs on Ge cell technology in support of larger area lighter weight power systems. Data are presented showing that individual 2 cm x 2 cm, 8 mil cell efficiencies up to 21.7 percent have been achieved. Efficiencies up to 24 percent AM0 will be possible by optimizing the GaAs/Ge interface. Cells have been welded without degradation using silver interconnects and have been laid down on an aluminum honeycomb/graphite facesheet substrate to produce a small coupon. The efficiency was 18.1 percent at AM0, 28 C.

Formation of SiGe nanocrystals embedded in Al{sub 2}O{sub 3} for the application of write-once-read-many-times memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Min-Lin; Wu, Yung-Hsien; Lin, Chia-Chun

2012-10-15

The structure of SiGe nanocrystals embedded in Al{sub 2}O{sub 3} formed by sequential deposition of Al{sub 2}O{sub 3}/Si/Ge/Al{sub 2}O{sub 3} and a subsequent annealing was confirmed by transmission electron microscopy and energy dispersive spectroscopy (EDS), and its application for write-once-read-many-times (WORM) memory devices was explored in this study. By applying a -10 V pulse for 1 s, a large amount of holes injected from Si substrate are stored in the nanocrystals and consequently, the current at +1.5 V increases by a factor of 10{sup 4} as compared to that of the initial state. Even with a smaller -5 V pulsemore » for 1 {mu}s, a sufficiently large current ratio of 36 can still be obtained, verifying the low power operation. Since holes are stored in nanocrystals which are isolated from Si substrate by Al{sub 2}O{sub 3} with good integrity and correspond to a large valence band offset with respect to Al{sub 2}O{sub 3}, desirable read endurance up to 10{sup 5} cycles and excellent retention over 100 yr are achieved. Combining these promising characteristics, WORM memory devices are appropriate for high-performance archival storage applications.« less

Surfactant-Mediated Growth of Ge/Si(001) Interface Studied by XPD

NASA Astrophysics Data System (ADS)

Gunnella, R.; Castrucci, P.; Pinto, N.; Cucculelli, P.; Davoli, I.; Sébilleau, D.; de Crescenzi, M.

The influence of Sb as a surfactant on the formation of Si/Ge interface is studied by means of XPD (X-ray photoelectron diffraction) and AED (Auger electron diffraction) from Ge and Si core levels. The technique employed is particularly suitable for checking the film tetragonal distortion, the growth morphology and the sharpness of the interface. We found a layer by layer growth mode for 3 ML of Ge on Si(001) and related values of strain of the film close to the value predicted by the elastic theory which enforces the use of such a surfactant to obtain high quality and sharp heterostructures. In addition, studying the influence of 3 ML of the Si cap layer on the 3 ML Ge, we obtain no indication of Ge segregation into the Si cap layer. Finally, evidences of quality degradation after high temperature (T > 600°C) annealing are shown.

Use of olive oil-in-water gelled emulsions in model turkey breast emulsions

NASA Astrophysics Data System (ADS)

Serdaroğlu, M.; Öztürk, B.

2017-09-01

Today, gelled emulsion systems offer a novel possibility in lipid modification of meat products. In this study, we aimed to investigate the quality characteristics of model turkey emulsions that were prepared with olive oil-in-water gelled emulsion (GE) as partial or total beef fat replacer. The results indicated that while most of the GE treatments showed equivalent emulsion characteristics in terms of emulsion stability, water-holding capacity and cook yield, utilization of 100% GE as the lipid source could increase total expressible fluid of the model turkey emulsion and thus negatively affect the quality. Utilization of GE was effective in total fat reduction, as the model turkey emulsions formulated with more than 50% GE had significantly lower fat content compared to full-beef fat control model emulsion. However, beef fat replacement with GE produced considerable changes in colour parameters. Finally, it was concluded that utilization of GE as a partial beef fat replacer has good potential to enhance stability and reduce total fat in turkey meat emulsion products.

Atypical self-activation of Ga dopant for Ge nanowire devices.

PubMed

Zeiner, Clemens; Lugstein, Alois; Burchhart, Thomas; Pongratz, Peter; Connell, Justin G; Lauhon, Lincoln J; Bertagnolli, Emmerich

2011-08-10

In this Letter we report the atypical self-activation of gallium (Ga) implanted by focused ion beam (FIB) into germanium nanowires (Ge-NWs). By FIB implantation of 30 keV Ga(+) ions at room temperature, the Ge-NW conductivity increases up to 3 orders of magnitude with increasing ion fluence. Cu(3)Ge heterostructures were formed by diffusion to ensure well-defined contacts to the NW and enable two point I/V measurements. Additional four point measurements prove that the conductivity enhancement emerges from the modification of the wires themselves and not from contact property modifications. The Ga distribution in the implanted Ge-NWs was measured using atom probe tomography. For high ion fluences, and beginning amorphization of the NWs, the conductivity decreases exponentially. Temperature dependent conductivity measurements show strong evidence for an in situ doping of the Ge-NWs without any further annealing. Finally the feasibility of improving the device performance of top-gated Ge-NW MOSFETs by FIB implantation was shown.

Transport and first-principles study of novel thermoelectric materials

NASA Astrophysics Data System (ADS)

Chi, Hang

Thermoelectric materials can recover waste industrial heat and convert it to electricity as well as provide efficient local cooling of electronic devices. The efficiency of such environmentally responsible and exceptionally reliable solid state energy conversion is determined by the dimensionless figure-of-merit ZT = alpha2 sigmaT/kappa, where alpha is the Seebeck coefficient, sigma is the electrical conductivity, kappa is the thermal conductivity, and T is the absolute temperature. The goal of the thesis is to (i) illustrate the physics to achieve high ZT of advanced thermoelectric materials and (ii) explore fundamental structure and transport properties in novel condensed matter systems, via an approach combining comprehensive experimental techniques and state-of-the-art first-principles simulation methods. Thermo-galvanomagnetic transport coefficients are derived from Onsager's reciprocal relations and evaluated via solving Boltzmann transport equation using Fermi-Dirac statistics, under the relaxation time approximation. Such understanding provides insights on enhancing ZT through two physically intuitive and very effective routes: (i) improving power factor PF = alpha2sigma; and (ii) reducing thermal conductivity kappa, as demonstrated in the cases of Mg2Si1-xSnx solid solution and Ge/Te double substituted skutterudites CoSb3(1-x)Ge1.5x Te1.5x, respectively. Motivated by recent theoretical predictions of enhanced thermoelectric performance in highly mismatched alloys, ZnTe:N molecular beam epitaxy (MBE) films deposited on GaAs (100) substrates are carefully examined, which leads to a surprising discovery of significant phonon-drag thermopower (reaching 1-2 mV/K-1) at ~13 K. Further systematic study in Bi2Te3 MBE thin films grown on sapphire (0001) and/or BaF2 (111) substrates, reveal that the peak of phonon drag can be tuned by the choice of substrates with different Debye temperatures. Moreover, the detailed transport and structure studies of Bi2-xTl xTe3 single crystals demonstrate that thallium doping leads to a bulk insulating state for such a topological insulator, which opens an avenue for further investigations of transport phenomena related to surface states. Finally, using the combined theoretical and experimental approaches, a new layered transition metal dichalcogenide type of ground state of Cu 2Se is proposed, which exhibits extraordinary weak anti-localization type of magnetoresistance at liquid helium temperatures.

Effect of Ge surface termination on oxidation behavior

NASA Astrophysics Data System (ADS)

Lee, Younghwan; Park, Kibyung; Cho, Yong Soo; Lim, Sangwoo

2008-09-01

Sulfur-termination was formed on the Ge(1 0 0) surface using (NH 4) 2S solution. Formation of Ge-S and the oxidation of the S-terminated Ge surface were monitored with multiple internal reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. In the 0.5, 5, or 20% (NH 4) 2S solution, H-termination on the Ge(1 0 0) surface was substituted with S-termination in 1 min. When the S-terminated Ge(1 0 0) surface was exposed in air ambient, the oxidation was retarded for about 3600 min. The preservation time of the oxide layer up to one monolayer of S-terminated Ge(1 0 0) surface was about 120 times longer than for the H-terminated Ge(1 0 0) surface. However, the oxidation of S-terminated Ge(1 0 0) surface drastically increased after the threshold time. There was no significant difference in threshold time between S-terminations formed in 0.5, 5, and 20% (NH 4) 2S solutions. With the surface oxidation, desorption of S on the Ge surface was observed. The desorption behavior of sulfur on the S-terminated Ge(1 0 0) surface was independent of the concentration of the (NH 4) 2S solution that forms S-termination. Non-ideal S-termination on Ge surfaces may be related to drastic oxidation of the Ge surface. Finally, with the desulfurization on the S-terminated Ge(1 0 0) surface, oxide growth is accelerated.

Synthesis and structure of novel lithium-ion conductor Li7Ge3PS12

NASA Astrophysics Data System (ADS)

Inoue, Yuki; Suzuki, Kota; Matsui, Naoki; Hirayama, Masaaki; Kanno, Ryoji

2017-02-01

The novel lithium-ion conductor Li7Ge3PS12 was synthesized by slow cooling from the ternary Li2S-GeS2-P2S5 system, and was shown to exhibit a cubic argyrodite-type structure. The phase composition was determined by varying the ratio of starting materials; the observed monophasic properties were close to those for the Li7Ge3PS12 composition. The lattice parameter (a =9.80192(3) Å) of Li7Ge3PS12 was slightly smaller than that of Li7PS6 (a =9.993 Å), indicating that substitution of a Li cation by the smaller Ge cation contracted the cubic lattice. In addition, the novel structure consisted of a framework composed of four isolated (Ge/P)S4 tetrahedra. Li+ ions occupied tetrahedral sites within the framework, forming a three-dimensional conduction pathway. Finally, Li7Ge3PS12 exhibited a high ionic conductivity of 1.1×10-4 S cm-1 at 25 °C and an activation energy of 25 kJ mol-1.

Rhombohedral Super Hetero Epitaxy of Cubic SiGe on Trigonal c-plane Sapphire

NASA Technical Reports Server (NTRS)

Choi, Sang H.; Duzik, Adam J.

2017-01-01

New rhombohedral super-hetero-epitaxy technology was developed at NASA. This epitaxy technology enables the growth of unprecedented cubic-trigonal hybrid single crystal structures with lattice match on sapphire (Al2O3) substrates, hence with little strain and very few defects at the interface.

Integrated, Flexible, High-efficiency Solar Cells: Epitaxial Lift-Off GaAs Solar Cells and Enabling Substrate Reuse

DTIC Science & Technology

2012-08-01

substrate cells. 3   GaAs CIGS CdTe α-SI Organic Trip. jun. Metam. C-Si Trip. Jun. Ge sub InP Power/Weight  Tradeoff...40   -  AR  coa<ng  ( ZnS /MgF2)150nm...AR  coa<ng  ( ZnS /MgF2)150nm                                      $5   -  HF

Performance of the PHENIX NCC Prototype

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Brien, E.; Kistenev, E.; Li, Z.

2006-10-27

The first prototype of NCC Si-W electromagnetic calorimeter have been built and tested at U-70 accelerator (IHEP, Protvino). Tests have been performed for 10 GeV electrons and 70 GeV protons.This paper describes design and construction of the prototype and tests results. Final prototype energy resolution is about 11% at 90% CL.

Searches for scalar leptoquarks in pp collisions at [Formula: see text] = 8 TeV with the ATLAS detector.

PubMed

Aad, G; Abbott, B; Abdallah, J; Abdinov, O; Aben, R; Abolins, M; AbouZeid, O S; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, B S; Adamczyk, L; Adams, D L; Adelman, J; Adomeit, S; Adye, T; Affolder, A A; Agatonovic-Jovin, T; Agricola, J; Aguilar-Saavedra, J A; Ahlen, S P; Ahmadov, F; Aielli, G; Akerstedt, H; Åkesson, T P A; Akimov, A V; Alberghi, G L; Albert, J; Albrand, S; Alconada Verzini, M J; Aleksa, M; Aleksandrov, I N; Alexa, C; Alexander, G; Alexopoulos, T; Alhroob, M; Alimonti, G; Alio, L; Alison, J; Alkire, S P; Allbrooke, B M M; Allport, P P; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Altheimer, A; Alvarez Gonzalez, B; Álvarez Piqueras, D; Alviggi, M G; Amadio, B T; Amako, K; Amaral Coutinho, Y; Amelung, C; Amidei, D; Amor Dos Santos, S P; Amorim, A; Amoroso, S; Amram, N; Amundsen, G; Anastopoulos, C; Ancu, L S; Andari, N; Andeen, T; Anders, C F; Anders, G; Anders, J K; Anderson, K J; Andreazza, A; Andrei, V; Angelidakis, S; Angelozzi, I; Anger, P; Angerami, A; Anghinolfi, F; Anisenkov, A V; Anjos, N; Annovi, A; Antonelli, M; Antonov, A; Antos, J; Anulli, F; Aoki, M; Aperio Bella, L; Arabidze, G; Arai, Y; Araque, J P; Arce, A T H; Arduh, F A; Arguin, J-F; Argyropoulos, S; Arik, M; Armbruster, A J; Arnaez, O; Arnal, V; Arnold, H; Arratia, M; Arslan, O; Artamonov, A; Artoni, G; Asai, S; Asbah, N; Ashkenazi, A; Åsman, B; Asquith, L; Assamagan, K; Astalos, R; Atkinson, M; Atlay, N B; Augsten, K; Aurousseau, M; Avolio, G; Axen, B; Ayoub, M K; Azuelos, G; Baak, M A; Baas, A E; Baca, M J; Bacci, C; Bachacou, H; Bachas, K; Backes, M; Backhaus, M; Bagiacchi, P; Bagnaia, P; Bai, Y; Bain, T; Baines, J T; Baker, O K; Baldin, E M; Balek, P; Balestri, T; Balli, F; Banas, E; Banerjee, Sw; Bannoura, A A E; Bansil, H S; Barak, L; Barberio, E L; Barberis, D; Barbero, M; Barillari, T; Barisonzi, M; Barklow, T; Barlow, N; Barnes, S L; Barnett, B M; Barnett, R M; Barnovska, Z; Baroncelli, A; Barone, G; Barr, A J; Barreiro, F; Barreiro Guimarães da Costa, J; Bartoldus, R; Barton, A E; Bartos, P; Basalaev, A; Bassalat, A; Basye, A; Bates, R L; Batista, S J; Batley, J R; Battaglia, M; Bauce, M; Bauer, F; Bawa, H S; Beacham, J B; Beattie, M D; Beau, T; Beauchemin, P H; Beccherle, R; Bechtle, P; Beck, H P; Becker, K; Becker, M; Beckingham, M; Becot, C; Beddall, A J; Beddall, A; Bednyakov, V A; Bee, C P; Beemster, L J; Beermann, T A; Begel, M; Behr, J K; Belanger-Champagne, C; Bell, W H; Bella, G; Bellagamba, L; Bellerive, A; Bellomo, M; Belotskiy, K; Beltramello, O; Benary, O; Benchekroun, D; Bender, M; Bendtz, K; Benekos, N; Benhammou, Y; Benhar Noccioli, E; Benitez Garcia, J A; Benjamin, D P; Bensinger, J R; Bentvelsen, S; Beresford, L; Beretta, M; Berge, D; Bergeaas Kuutmann, E; Berger, N; Berghaus, F; Beringer, J; Bernard, C; Bernard, N R; Bernius, C; Bernlochner, F U; Berry, T; Berta, P; Bertella, C; Bertoli, G; Bertolucci, F; Bertsche, C; Bertsche, D; Besana, M I; Besjes, G J; Bessidskaia Bylund, O; Bessner, M; Besson, N; Betancourt, C; Bethke, S; Bevan, A J; Bhimji, W; Bianchi, R M; Bianchini, L; Bianco, M; Biebel, O; Biedermann, D; Bieniek, S P; Biglietti, M; Bilbao De Mendizabal, J; Bilokon, H; Bindi, M; Binet, S; Bingul, A; Bini, C; Biondi, S; Bjergaard, D M; Black, C W; Black, J E; Black, K M; Blackburn, D; Blair, R E; Blanchard, J-B; Blanco, J E; Blazek, T; Bloch, I; Blocker, C; Blum, W; Blumenschein, U; Bobbink, G J; Bobrovnikov, V S; Bocchetta, S S; Bocci, A; Bock, C; Boehler, M; Bogaerts, J A; Bogavac, D; Bogdanchikov, A G; Bohm, C; Boisvert, V; Bold, T; Boldea, V; Boldyrev, A S; Bomben, M; Bona, M; Boonekamp, M; Borisov, A; Borissov, G; Borroni, S; Bortfeldt, J; Bortolotto, V; Bos, K; Boscherini, D; Bosman, M; Boudreau, J; Bouffard, J; Bouhova-Thacker, E V; Boumediene, D; Bourdarios, C; Bousson, N; Boutle, S K; Boveia, A; Boyd, J; Boyko, I R; Bozic, I; Bracinik, J; Brandt, A; Brandt, G; Brandt, O; Bratzler, U; Brau, B; Brau, J E; Braun, H M; Brazzale, S F; Breaden Madden, W D; Brendlinger, K; Brennan, A J; Brenner, L; Brenner, R; Bressler, S; Bristow, K; Bristow, T M; Britton, D; Britzger, D; Brochu, F M; Brock, I; Brock, R; Bronner, J; Brooijmans, G; Brooks, T; Brooks, W K; Brosamer, J; Brost, E; Brown, J; Bruckman de Renstrom, P A; Bruncko, D; Bruneliere, R; Bruni, A; Bruni, G; Bruschi, M; Bruscino, N; Bryngemark, L; Buanes, T; Buat, Q; Buchholz, P; Buckley, A G; Buda, S I; Budagov, I A; Buehrer, F; Bugge, L; Bugge, M K; Bulekov, O; Bullock, D; Burckhart, H; Burdin, S; Burgard, C D; Burghgrave, B; Burke, S; Burmeister, I; Busato, E; Büscher, D; Büscher, V; Bussey, P; Butler, J M; Butt, A I; Buttar, C M; Butterworth, J M; Butti, P; Buttinger, W; Buzatu, A; Buzykaev, A R; CabreraUrbán, S; Caforio, D; Cairo, V M; Cakir, O; Calace, N; Calafiura, P; Calandri, A; Calderini, G; Calfayan, P; Caloba, L P; Calvet, D; Calvet, S; Camacho Toro, R; Camarda, S; Camarri, P; Cameron, D; Caminal Armadans, R; Campana, S; Campanelli, M; Campoverde, A; Canale, V; Canepa, A; Cano Bret, M; Cantero, J; Cantrill, R; Cao, T; Capeans Garrido, M D M; Caprini, I; Caprini, M; Capua, M; Caputo, R; Cardarelli, R; Cardillo, F; Carli, T; Carlino, G; Carminati, L; Caron, S; Carquin, E; Carrillo-Montoya, G D; Carter, J R; Carvalho, J; Casadei, D; Casado, M P; Casolino, M; Castaneda-Miranda, E; Castelli, A; Castillo Gimenez, V; Castro, N F; Catastini, P; Catinaccio, A; Catmore, J R; Cattai, A; Caudron, J; Cavaliere, V; Cavalli, D; Cavalli-Sforza, M; Cavasinni, V; Ceradini, F; Cerio, B C; Cerny, K; Cerqueira, A S; Cerri, A; Cerrito, L; Cerutti, F; Cerv, M; Cervelli, A; Cetin, S A; Chafaq, A; Chakraborty, D; Chalupkova, I; Chang, P; Chapman, J D; Charlton, D G; Chau, C C; Chavez Barajas, C A; Cheatham, S; Chegwidden, A; Chekanov, S; Chekulaev, S V; Chelkov, G A; Chelstowska, M A; Chen, C; Chen, H; Chen, K; Chen, L; Chen, S; Chen, S; Chen, X; Chen, Y; Cheng, H C; Cheng, Y; Cheplakov, A; Cheremushkina, E; Cherkaoui El Moursli, R; Chernyatin, V; Cheu, E; Chevalier, L; Chiarella, V; Chiarelli, G; Chiodini, G; Chisholm, A S; Chislett, R T; Chitan, A; Chizhov, M V; Choi, K; Chouridou, S; Chow, B K B; Christodoulou, V; Chromek-Burckhart, D; Chudoba, J; Chuinard, A J; Chwastowski, J J; Chytka, L; Ciapetti, G; Ciftci, A K; Cinca, D; Cindro, V; Cioara, I A; Ciocio, A; Cirotto, F; Citron, Z H; Ciubancan, M; Clark, A; Clark, B L; Clark, P J; Clarke, R N; Cleland, W; Clement, C; Coadou, Y; Cobal, M; Coccaro, A; Cochran, J; Coffey, L; Cogan, J G; Colasurdo, L; Cole, B; Cole, S; Colijn, A P; Collot, J; Colombo, T; Compostella, G; Conde Muiño, P; Coniavitis, E; Connell, S H; Connelly, I A; Consorti, V; Constantinescu, S; Conta, C; Conti, G; Conventi, F; Cooke, M; Cooper, B D; Cooper-Sarkar, A M; Cornelissen, T; Corradi, M; Corriveau, F; Corso-Radu, A; Cortes-Gonzalez, A; Cortiana, G; Costa, G; Costa, M J; Costanzo, D; Côté, D; Cottin, G; Cowan, G; Cox, B E; Cranmer, K; Cree, G; Crépé-Renaudin, S; Crescioli, F; Cribbs, W A; Crispin Ortuzar, M; Cristinziani, M; Croft, V; Crosetti, G; Cuhadar Donszelmann, T; Cummings, J; Curatolo, M; Cúth, J; Cuthbert, C; Czirr, H; Czodrowski, P; D'Auria, S; D'Onofrio, M; Da Cunha Sargedas De Sousa, M J; DaVia, C; Dabrowski, W; Dafinca, A; Dai, T; Dale, O; Dallaire, F; Dallapiccola, C; Dam, M; Dandoy, J R; Dang, N P; Daniells, A C; Danninger, M; Dano Hoffmann, M; Dao, V; Darbo, G; Darmora, S; Dassoulas, J; Dattagupta, A; Davey, W; David, C; Davidek, T; Davies, E; Davies, M; Davison, P; Davygora, Y; Dawe, E; Dawson, I; Daya-Ishmukhametova, R K; De, K; de Asmundis, R; De Benedetti, A; De Castro, S; De Cecco, S; De Groot, N; de Jong, P; De la Torre, H; De Lorenzi, F; De Pedis, D; De Salvo, A; De Sanctis, U; De Santo, A; De Vivie De Regie, J B; Dearnaley, W J; Debbe, R; Debenedetti, C; Dedovich, D V; Deigaard, I; Del Peso, J; Del Prete, T; Delgove, D; Deliot, F; Delitzsch, C M; Deliyergiyev, M; Dell'Acqua, A; Dell'Asta, L; Dell'Orso, M; Della Pietra, M; Della Volpe, D; Delmastro, M; Delsart, P A; Deluca, C; DeMarco, D A; Demers, S; Demichev, M; Demilly, A; Denisov, S P; Derendarz, D; Derkaoui, J E; Derue, F; Dervan, P; Desch, K; Deterre, C; Deviveiros, P O; Dewhurst, A; Dhaliwal, S; Di Ciaccio, A; Di Ciaccio, L; Di Domenico, A; Di Donato, C; Di Girolamo, A; Di Girolamo, B; Di Mattia, A; Di Micco, B; Di Nardo, R; Di Simone, A; Di Sipio, R; Di Valentino, D; Diaconu, C; Diamond, M; Dias, F A; Diaz, M A; Diehl, E B; Dietrich, J; Diglio, S; Dimitrievska, A; Dingfelder, J; Dita, P; Dita, S; Dittus, F; Djama, F; Djobava, T; Djuvsland, J I; do Vale, M A B; Dobos, D; Dobre, M; Doglioni, C; Dohmae, T; Dolejsi, J; Dolezal, Z; Dolgoshein, B A; Donadelli, M; Donati, S; Dondero, P; Donini, J; Dopke, J; Doria, A; Dova, M T; Doyle, A T; Drechsler, E; Dris, M; Dubreuil, E; Duchovni, E; Duckeck, G; Ducu, O A; Duda, D; Dudarev, A; Duflot, L; Duguid, L; Dührssen, M; Dunford, M; Duran Yildiz, H; Düren, M; Durglishvili, A; Duschinger, D; Dyndal, M; Eckardt, C; Ecker, K M; Edgar, R C; Edson, W; Edwards, N C; Ehrenfeld, W; Eifert, T; Eigen, G; Einsweiler, K; Ekelof, T; El Kacimi, M; Ellert, M; Elles, S; Ellinghaus, F; Elliot, A A; Ellis, N; Elmsheuser, J; Elsing, M; Emeliyanov, D; Enari, Y; Endner, O C; Endo, M; Erdmann, J; Ereditato, A; Ernis, G; Ernst, J; Ernst, M; Errede, S; Ertel, E; Escalier, M; Esch, H; Escobar, C; Esposito, B; Etienvre, A I; Etzion, E; Evans, H; Ezhilov, A; Fabbri, L; Facini, G; Fakhrutdinov, R M; Falciano, S; Falla, R J; Faltova, J; Fang, Y; Fanti, M; Farbin, A; Farilla, A; Farooque, T; Farrell, S; Farrington, S M; Farthouat, P; Fassi, F; Fassnacht, P; Fassouliotis, D; Faucci Giannelli, M; Favareto, A; Fayard, L; Federic, P; Fedin, O L; Fedorko, W; Feigl, S; Feligioni, L; Feng, C; Feng, E J; Feng, H; Fenyuk, A B; Feremenga, L; FernandezMartinez, P; Fernandez Perez, S; Ferrando, J; Ferrari, A; Ferrari, P; Ferrari, R; Ferreira de Lima, D E; Ferrer, A; Ferrere, D; Ferretti, C; FerrettoParodi, A; Fiascaris, M; Fiedler, F; Filipčič, A; Filipuzzi, M; Filthaut, F; Fincke-Keeler, M; Finelli, K D; Fiolhais, M C N; Fiorini, L; Firan, A; Fischer, A; Fischer, C; Fischer, J; Fisher, W C; Fitzgerald, E A; Flaschel, N; Fleck, I; Fleischmann, P; Fleischmann, S; Fletcher, G T; Fletcher, G; Fletcher, R R M; Flick, T; Floderus, A; Flores Castillo, L R; Flowerdew, M J; Formica, A; Forti, A; Fournier, D; Fox, H; Fracchia, S; Francavilla, P; Franchini, M; Francis, D; Franconi, L; Franklin, M; Frate, M; Fraternali, M; Freeborn, D; French, S T; Friedrich, F; Froidevaux, D; Frost, J A; Fukunaga, C; Fullana Torregrosa, E; Fulsom, B G; Fusayasu, T; Fuster, J; Gabaldon, C; Gabizon, O; Gabrielli, A; Gabrielli, A; Gach, G P; Gadatsch, S; Gadomski, S; Gagliardi, G; Gagnon, P; Galea, C; Galhardo, B; Gallas, E J; Gallop, B J; Gallus, P; Galster, G; Gan, K K; Gao, J; Gao, Y; Gao, Y S; GarayWalls, F M; Garberson, F; García, C; García Navarro, J E; Garcia-Sciveres, M; Gardner, R W; Garelli, N; Garonne, V; Gatti, C; Gaudiello, A; Gaudio, G; Gaur, B; Gauthier, L; Gauzzi, P; Gavrilenko, I L; Gay, C; Gaycken, G; Gazis, E N; Ge, P; Gecse, Z; Gee, C N P; Geich-Gimbel, Ch; Geisler, M P; Gemme, C; Genest, M H; Gentile, S; George, M; George, S; Gerbaudo, D; Gershon, A; Ghasemi, S; Ghazlane, H; Giacobbe, B; Giagu, S; Giangiobbe, V; Giannetti, P; Gibbard, B; Gibson, S M; Gilchriese, M; Gillam, T P S; Gillberg, D; Gilles, G; Gingrich, D M; Giokaris, N; Giordani, M P; Giorgi, F M; Giorgi, F M; Giraud, P F; Giromini, P; Giugni, D; Giuliani, C; Giulini, M; Gjelsten, B K; Gkaitatzis, S; Gkialas, I; Gkougkousis, E L; Gladilin, L K; Glasman, C; Glatzer, J; Glaysher, P C F; Glazov, A; Goblirsch-Kolb, M; Goddard, J R; Godlewski, J; Goldfarb, S; Golling, T; Golubkov, D; Gomes, A; Gonçalo, R; Goncalves Pinto Firmino Da Costa, J; Gonella, L; González de la Hoz, S; Gonzalez Parra, G; Gonzalez-Sevilla, S; Goossens, L; Gorbounov, P A; Gordon, H A; Gorelov, I; Gorini, B; Gorini, E; Gorišek, A; Gornicki, E; Goshaw, A T; Gössling, C; Gostkin, M I; Goujdami, D; Goussiou, A G; Govender, N; Gozani, E; Grabas, H M X; Graber, L; Grabowska-Bold, I; Gradin, P O J; Grafström, P; Grahn, K-J; Gramling, J; Gramstad, E; Grancagnolo, S; Gratchev, V; Gray, H M; Graziani, E; Greenwood, Z D; Grefe, C; Gregersen, K; Gregor, I M; Grenier, P; Griffiths, J; Grillo, A A; Grimm, K; Grinstein, S; Gris, Ph; Grivaz, J-F; Grohs, J P; Grohsjean, A; Gross, E; Grosse-Knetter, J; Grossi, G C; Grout, Z J; Guan, L; Guenther, J; Guescini, F; Guest, D; Gueta, O; Guido, E; Guillemin, T; Guindon, S; Gul, U; Gumpert, C; Guo, J; Guo, Y; Gupta, S; Gustavino, G; Gutierrez, P; Gutierrez Ortiz, N G; Gutschow, C; Guyot, C; Gwenlan, C; Gwilliam, C B; Haas, A; Haber, C; Hadavand, H K; Haddad, N; Haefner, P; Hageböck, S; Hajduk, Z; Hakobyan, H; Haleem, M; Haley, J; Hall, D; Halladjian, G; Hallewell, G D; Hamacher, K; Hamal, P; Hamano, K; Hamilton, A; Hamity, G N; Hamnett, P G; Han, L; Hanagaki, K; Hanawa, K; Hance, M; Haney, B; Hanke, P; Hanna, R; Hansen, J B; Hansen, J D; Hansen, M C; Hansen, P H; Hara, K; Hard, A S; Harenberg, T; Hariri, F; Harkusha, S; Harrington, R D; Harrison, P F; Hartjes, F; Hasegawa, M; Hasegawa, Y; Hasib, A; Hassani, S; Haug, S; Hauser, R; Hauswald, L; Havranek, M; Hawkes, C M; Hawkings, R J; Hawkins, A D; Hayashi, T; Hayden, D; Hays, C P; Hays, J M; Hayward, H S; Haywood, S J; Head, S J; Heck, T; Hedberg, V; Heelan, L; Heim, S; Heim, T; Heinemann, B; Heinrich, L; Hejbal, J; Helary, L; Hellman, S; Hellmich, D; Helsens, C; Henderson, J; Henderson, R C W; Heng, Y; Hengler, C; Henkelmann, S; Henrichs, A; Henriques Correia, A M; Henrot-Versille, S; Herbert, G H; Hernández Jiménez, Y; Herrberg-Schubert, R; Herten, G; Hertenberger, R; Hervas, L; Hesketh, G G; Hessey, N P; Hetherly, J W; Hickling, R; Higón-Rodriguez, E; Hill, E; Hill, J C; Hiller, K H; Hillier, S J; Hinchliffe, I; Hines, E; Hinman, R R; Hirose, M; Hirschbuehl, D; Hobbs, J; Hod, N; Hodgkinson, M C; Hodgson, P; Hoecker, A; Hoeferkamp, M R; Hoenig, F; Hohlfeld, M; Hohn, D; Holmes, T R; Homann, M; Hong, T M; Hooft van Huysduynen, L; Hopkins, W H; Horii, Y; Horton, A J; Hostachy, J-Y; Hou, S; Hoummada, A; Howard, J; Howarth, J; Hrabovsky, M; Hristova, I; Hrivnac, J; Hryn'ova, T; Hrynevich, A; Hsu, C; Hsu, P J; Hsu, S-C; Hu, D; Hu, Q; Hu, X; Huang, Y; Hubacek, Z; Hubaut, F; Huegging, F; Huffman, T B; Hughes, E W; Hughes, G; Huhtinen, M; Hülsing, T A; Huseynov, N; Huston, J; Huth, J; Iacobucci, G; Iakovidis, G; Ibragimov, I; Iconomidou-Fayard, L; Ideal, E; Idrissi, Z; Iengo, P; Igonkina, O; Iizawa, T; Ikegami, Y; Ikematsu, K; Ikeno, M; Ilchenko, Y; Iliadis, D; Ilic, N; Ince, T; Introzzi, G; Ioannou, P; Iodice, M; Iordanidou, K; Ippolito, V; Irles Quiles, A; Isaksson, C; Ishino, M; Ishitsuka, M; Ishmukhametov, R; Issever, C; Istin, S; Iturbe Ponce, J M; Iuppa, R; Ivarsson, J; Iwanski, W; Iwasaki, H; Izen, J M; Izzo, V; Jabbar, S; Jackson, B; Jackson, M; Jackson, P; Jaekel, M R; Jain, V; Jakobs, K; Jakobsen, S; Jakoubek, T; Jakubek, J; Jamin, D O; Jana, D K; Jansen, E; Jansky, R; Janssen, J; Janus, M; Jarlskog, G; Javadov, N; Javůrek, T; Jeanty, L; Jejelava, J; Jeng, G-Y; Jennens, D; Jenni, P; Jentzsch, J; Jeske, C; Jézéquel, S; Ji, H; Jia, J; Jiang, Y; Jiggins, S; Jimenez Pena, J; Jin, S; Jinaru, A; Jinnouchi, O; Joergensen, M D; Johansson, P; Johns, K A; Jon-And, K; Jones, G; Jones, R W L; Jones, T J; Jongmanns, J; Jorge, P M; Joshi, K D; Jovicevic, J; Ju, X; Jung, C A; Jussel, P; Juste Rozas, A; Kaci, M; Kaczmarska, A; Kado, M; Kagan, H; Kagan, M; Kahn, S J; Kajomovitz, E; Kalderon, C W; Kama, S; Kamenshchikov, A; Kanaya, N; Kaneti, S; Kantserov, V A; Kanzaki, J; Kaplan, B; Kaplan, L S; Kapliy, A; Kar, D; Karakostas, K; Karamaoun, A; Karastathis, N; Kareem, M J; Karentzos, E; Karnevskiy, M; Karpov, S N; Karpova, Z M; Karthik, K; Kartvelishvili, V; Karyukhin, A N; Kasahara, K; Kashif, L; Kass, R D; Kastanas, A; Kataoka, Y; Kato, C; Katre, A; Katzy, J; Kawagoe, K; Kawamoto, T; Kawamura, G; Kazama, S; Kazanin, V F; Keeler, R; Kehoe, R; Keller, J S; Kempster, J J; Keoshkerian, H; Kepka, O; Kerševan, B P; Kersten, S; Keyes, R A; Khalil-Zada, F; Khandanyan, H; Khanov, A; Kharlamov, A G; Khoo, T J; Khovanskiy, V; Khramov, E; Khubua, J; Kido, S; Kim, H Y; Kim, S H; Kim, Y K; Kimura, N; Kind, O M; King, B T; King, M; King, S B; Kirk, J; Kiryunin, A E; Kishimoto, T; Kisielewska, D; Kiss, F; Kiuchi, K; Kivernyk, O; Kladiva, E; Klein, M H; Klein, M; Klein, U; Kleinknecht, K; Klimek, P; Klimentov, A; Klingenberg, R; Klinger, J A; Klioutchnikova, T; Kluge, E-E; Kluit, P; Kluth, S; Knapik, J; Kneringer, E; Knoops, E B F G; Knue, A; Kobayashi, A; Kobayashi, D; Kobayashi, T; Kobel, M; Kocian, M; Kodys, P; Koffas, T; Koffeman, E; Kogan, L A; Kohlmann, S; Kohout, Z; Kohriki, T; Koi, T; Kolanoski, H; Koletsou, I; Komar, A A; Komori, Y; Kondo, T; Kondrashova, N; Köneke, K; König, A C; Kono, T; Konoplich, R; Konstantinidis, N; Kopeliansky, R; Koperny, S; Köpke, L; Kopp, A K; Korcyl, K; Kordas, K; Korn, A; Korol, A A; Korolkov, I; Korolkova, E V; Kortner, O; Kortner, S; Kosek, T; Kostyukhin, V V; Kotov, V M; Kotwal, A; Kourkoumeli-Charalampidi, A; Kourkoumelis, C; Kouskoura, V; Koutsman, A; Kowalewski, R; Kowalski, T Z; Kozanecki, W; Kozhin, A S; Kramarenko, V A; Kramberger, G; Krasnopevtsev, D; Krasny, M W; Krasznahorkay, A; Kraus, J K; Kravchenko, A; Kreiss, S; Kretz, M; Kretzschmar, J; Kreutzfeldt, K; Krieger, P; Krizka, K; Kroeninger, K; Kroha, H; Kroll, J; Kroseberg, J; Krstic, J; Kruchonak, U; Krüger, H; Krumnack, N; Kruse, A; Kruse, M C; Kruskal, M; Kubota, T; Kucuk, H; Kuday, S; Kuehn, S; Kugel, A; Kuger, F; Kuhl, A; Kuhl, T; Kukhtin, V; Kukla, R; Kulchitsky, Y; Kuleshov, S; Kuna, M; Kunigo, T; Kupco, A; Kurashige, H; Kurochkin, Y A; Kus, V; Kuwertz, E S; Kuze, M; Kvita, J; Kwan, T; Kyriazopoulos, D; LaRosa, A; La RosaNavarro, J L; La Rotonda, L; Lacasta, C; Lacava, F; Lacey, J; Lacker, H; Lacour, D; Lacuesta, V R; Ladygin, E; Lafaye, R; Laforge, B; Lagouri, T; Lai, S; Lambourne, L; Lammers, S; Lampen, C L; Lampl, W; Lançon, E; Landgraf, U; Landon, M P J; Lang, V S; Lange, J C; Lankford, A J; Lanni, F; Lantzsch, K; Lanza, A; Laplace, S; Lapoire, C; Laporte, J F; Lari, T; Lasagni Manghi, F; Lassnig, M; Laurelli, P; Lavrijsen, W; Law, A T; Laycock, P; Lazovich, T; Le Dortz, O; Le Guirriec, E; Le Menedeu, E; LeBlanc, M; Le Compte, T; Ledroit-Guillon, F; Lee, C A; Lee, S C; Lee, L; Lefebvre, G; Lefebvre, M; Legger, F; Leggett, C; Lehan, A; Lehmann Miotto, G; Lei, X; Leight, W A; Leisos, A; Leister, A G; Leite, M A L; Leitner, R; Lellouch, D; Lemmer, B; Leney, K J C; Lenz, T; Lenzi, B; Leone, R; Leone, S; Leonidopoulos, C; Leontsinis, S; Leroy, C; Lester, C G; Levchenko, M; Levêque, J; Levin, D; Levinson, L J; Levy, M; Lewis, A; Leyko, A M; Leyton, M; Li, B; Li, H; Li, H L; Li, L; Li, L; Li, S; Li, X; Li, Y; Liang, Z; Liao, H; Liberti, B; Liblong, A; Lichard, P; Lie, K; Liebal, J; Liebig, W; Limbach, C; Limosani, A; Lin, S C; Lin, T H; Linde, F; Lindquist, B E; Linnemann, J T; Lipeles, E; Lipniacka, A; Lisovyi, M; Liss, T M; Lissauer, D; Lister, A; Litke, A M; Liu, B; Liu, D; Liu, H; Liu, J; Liu, J B; Liu, K; Liu, L; Liu, M; Liu, M; Liu, Y; Livan, M; Lleres, A; Llorente Merino, J; Lloyd, S L; Lo Sterzo, F; Lobodzinska, E; Loch, P; Lockman, W S; Loebinger, F K; Loevschall-Jensen, A E; Loew, K M; Loginov, A; Lohse, T; Lohwasser, K; Lokajicek, M; Long, B A; Long, J D; Long, R E; Looper, K A; Lopes, L; Lopez Mateos, D; Lopez Paredes, B; Lopez Paz, I; Lorenz, J; Lorenzo Martinez, N; Losada, M; Lösel, P J; Lou, X; Lounis, A; Love, J; Love, P A; Lu, N; Lubatti, H J; Luci, C; Lucotte, A; Luehring, F; Lukas, W; Luminari, L; Lundberg, O; Lund-Jensen, B; Lynn, D; Lysak, R; Lytken, E; Ma, H; Ma, L L; Maccarrone, G; Macchiolo, A; Macdonald, C M; Maček, B; Machado Miguens, J; Macina, D; Madaffari, D; Madar, R; Maddocks, H J; Mader, W F; Madsen, A; Maeda, J; Maeland, S; Maeno, T; Maevskiy, A; Magradze, E; Mahboubi, K; Mahlstedt, J; Maiani, C; Maidantchik, C; Maier, A A; Maier, T; Maio, A; Majewski, S; Makida, Y; Makovec, N; Malaescu, B; Malecki, Pa; Maleev, V P; Malek, F; Mallik, U; Malon, D; Malone, C; Maltezos, S; Malyshev, V M; Malyukov, S; Mamuzic, J; Mancini, G; Mandelli, B; Mandelli, L; Mandić, I; Mandrysch, R; Maneira, J; Manfredini, A; Manhaes de AndradeFilho, L; Manjarres Ramos, J; Mann, A; Manousakis-Katsikakis, A; Mansoulie, B; Mantifel, R; Mantoani, M; Mapelli, L; March, L; Marchiori, G; Marcisovsky, M; Marino, C P; Marjanovic, M; Marley, D E; Marroquim, F; Marsden, S P; Marshall, Z; Marti, L F; Marti-Garcia, S; Martin, B; Martin, T A; Martin, V J; Martin Dit Latour, B; Martinez, M; Martin-Haugh, S; Martoiu, V S; Martyniuk, A C; Marx, M; Marzano, F; Marzin, A; Masetti, L; Mashimo, T; Mashinistov, R; Masik, J; Maslennikov, A L; Massa, I; Massa, L; Mastrandrea, P; Mastroberardino, A; Masubuchi, T; Mättig, P; Mattmann, J; Maurer, J; Maxfield, S J; Maximov, D A; Mazini, R; Mazza, S M; Mazzaferro, L; McGoldrick, G; Mc Kee, S P; McCarn, A; McCarthy, R L; McCarthy, T G; McCubbin, N A; McFarlane, K W; Mcfayden, J A; Mchedlidze, G; McMahon, S J; McPherson, R A; Medinnis, M; Meehan, S; Mehlhase, S; Mehta, A; Meier, K; Meineck, C; Meirose, B; Mellado Garcia, B R; Meloni, F; Mengarelli, A; Menke, S; Meoni, E; Mercurio, K M; Mergelmeyer, S; Mermod, P; Merola, L; Meroni, C; Merritt, F S; Messina, A; Metcalfe, J; Mete, A S; Meyer, C; Meyer, C; Meyer, J-P; Meyer, J; Meyer Zu Theenhausen, H; Middleton, R P; Miglioranzi, S; Mijović, L; Mikenberg, G; Mikestikova, M; Mikuž, M; Milesi, M; Milic, A; Miller, D W; Mills, C; Milov, A; Milstead, D A; Minaenko, A A; Minami, Y; Minashvili, I A; Mincer, A I; Mindur, B; Mineev, M; Ming, Y; Mir, L M; Mistry, K P; Mitani, T; Mitrevski, J; Mitsou, V A; Miucci, A; Miyagawa, P S; Mjörnmark, J U; Moa, T; Mochizuki, K; Mohapatra, S; Mohr, W; Molander, S; Moles-Valls, R; Monden, R; Mönig, K; Monini, C; Monk, J; Monnier, E; MontejoBerlingen, J; Monticelli, F; Monzani, S; Moore, R W; Morange, N; Moreno, D; MorenoLlácer, M; Morettini, P; Mori, D; Mori, T; Morii, M; Morinaga, M; Morisbak, V; Moritz, S; Morley, A K; Mornacchi, G; Morris, J D; Mortensen, S S; Morton, A; Morvaj, L; Mosidze, M; Moss, J; Motohashi, K; Mount, R; Mountricha, E; Mouraviev, S V; Moyse, E J W; Muanza, S; Mudd, R D; Mueller, F; Mueller, J; Mueller, R S P; Mueller, T; Muenstermann, D; Mullen, P; Mullier, G A; Murillo Quijada, J A; Murray, W J; Musheghyan, H; Musto, E; Myagkov, A G; Myska, M; Nachman, B P; Nackenhorst, O; Nadal, J; Nagai, K; Nagai, R; Nagai, Y; Nagano, K; Nagarkar, A; Nagasaka, Y; Nagata, K; Nagel, M; Nagy, E; Nairz, A M; Nakahama, Y; Nakamura, K; Nakamura, T; Nakano, I; Namasivayam, H; Naranjo Garcia, R F; Narayan, R; Narrias Villar, D I; Naumann, T; Navarro, G; Nayyar, R; Neal, H A; Nechaeva, P Yu; Neep, T J; Nef, P D; Negri, A; Negrini, M; Nektarijevic, S; Nellist, C; Nelson, A; Nemecek, S; Nemethy, P; Nepomuceno, A A; Nessi, M; Neubauer, M S; Neumann, M; Neves, R M; Nevski, P; Newman, P R; Nguyen, D H; Nickerson, R B; Nicolaidou, R; Nicquevert, B; Nielsen, J; Nikiforou, N; Nikiforov, A; Nikolaenko, V; Nikolic-Audit, I; Nikolopoulos, K; Nilsen, J K; Nilsson, P; Ninomiya, Y; Nisati, A; Nisius, R; Nobe, T; Nomachi, M; Nomidis, I; Nooney, T; Norberg, S; Nordberg, M; Novgorodova, O; Nowak, S; Nozaki, M; Nozka, L; Ntekas, K; Nunes Hanninger, G; Nunnemann, T; Nurse, E; Nuti, F; O'Brien, B J; O'grady, F; O'Neil, D C; O'Shea, V; Oakham, F G; Oberlack, H; Obermann, T; Ocariz, J; Ochi, A; Ochoa, I; Ochoa-Ricoux, J P; Oda, S; Odaka, S; Ogren, H; Oh, A; Oh, S H; Ohm, C C; Ohman, H; Oide, H; Okamura, W; Okawa, H; Okumura, Y; Okuyama, T; Olariu, A; Olivares Pino, S A; Oliveira Damazio, D; Oliver Garcia, E; Olszewski, A; Olszowska, J; Onofre, A; Onogi, K; Onyisi, P U E; Oram, C J; Oreglia, M J; Oren, Y; Orestano, D; Orlando, N; Oropeza Barrera, C; Orr, R S; Osculati, B; Ospanov, R; Otero Y Garzon, G; Otono, H; Ouchrif, M; Ould-Saada, F; Ouraou, A; Oussoren, K P; Ouyang, Q; Ovcharova, A; Owen, M; Owen, R E; Ozcan, V E; Ozturk, N; Pachal, K; PachecoPages, A; Padilla Aranda, C; Pagáčová, M; Pagan Griso, S; Paganis, E; Paige, F; Pais, P; Pajchel, K; Palacino, G; Palestini, S; Palka, M; Pallin, D; Palma, A; Pan, Y B; Panagiotopoulou, E; Pandini, C E; Panduro Vazquez, J G; Pani, P; Panitkin, S; Pantea, D; Paolozzi, L; Papadopoulou, Th D; Papageorgiou, K; Paramonov, A; Paredes Hernandez, D; Parker, M A; Parker, K A; Parodi, F; Parsons, J A; Parzefall, U; Pasqualucci, E; Passaggio, S; Pastore, F; Pastore, Fr; Pásztor, G; Pataraia, S; Patel, N D; Pater, J R; Pauly, T; Pearce, J; Pearson, B; Pedersen, L E; Pedersen, M; Pedraza Lopez, S; Pedro, R; Peleganchuk, S V; Pelikan, D; Penc, O; Peng, C; Peng, H; Penning, B; Penwell, J; Perepelitsa, D V; Perez Codina, E; PérezGarcía-Estañ, M T; Perini, L; Pernegger, H; Perrella, S; Peschke, R; Peshekhonov, V D; Peters, K; Peters, R F Y; Petersen, B A; Petersen, T C; Petit, E; Petridis, A; Petridou, C; Petroff, P; Petrolo, E; Petrucci, F; Pettersson, N E; Pezoa, R; Phillips, P W; Piacquadio, G; Pianori, E; Picazio, A; Piccaro, E; Piccinini, M; Pickering, M A; Piegaia, R; Pignotti, D T; Pilcher, J E; Pilkington, A D; Pina, J; Pinamonti, M; Pinfold, J L; Pingel, A; Pires, S; Pirumov, H; Pitt, M; Pizio, C; Plazak, L; Pleier, M-A; Pleskot, V; Plotnikova, E; Plucinski, P; Pluth, D; Poettgen, R; Poggioli, L; Pohl, D; Polesello, G; Poley, A; Policicchio, A; Polifka, R; Polini, A; Pollard, C S; Polychronakos, V; Pommès, K; Pontecorvo, L; Pope, B G; Popeneciu, G A; Popovic, D S; Poppleton, A; Pospisil, S; Potamianos, K; Potrap, I N; Potter, C J; Potter, C T; Poulard, G; Poveda, J; Pozdnyakov, V; Pralavorio, P; Pranko, A; Prasad, S; Prell, S; Price, D; Price, L E; Primavera, M; Prince, S; Proissl, M; Prokofiev, K; Prokoshin, F; Protopapadaki, E; Protopopescu, S; Proudfoot, J; Przybycien, M; Ptacek, E; Puddu, D; Pueschel, E; Puldon, D; Purohit, M; Puzo, P; Qian, J; Qin, G; Qin, Y; Quadt, A; Quarrie, D R; Quayle, W B; Queitsch-Maitland, M; Quilty, D; Raddum, S; Radeka, V; Radescu, V; Radhakrishnan, S K; Radloff, P; Rados, P; Ragusa, F; Rahal, G; Rajagopalan, S; Rammensee, M; Rangel-Smith, C; Rauscher, F; Rave, S; Ravenscroft, T; Raymond, M; Read, A L; Readioff, N P; Rebuzzi, D M; Redelbach, A; Redlinger, G; Reece, R; Reeves, K; Rehnisch, L; Reichert, J; Reisin, H; Relich, M; Rembser, C; Ren, H; Renaud, A; Rescigno, M; Resconi, S; Rezanova, O L; Reznicek, P; Rezvani, R; Richter, R; Richter, S; Richter-Was, E; Ricken, O; Ridel, M; Rieck, P; Riegel, C J; Rieger, J; Rifki, O; Rijssenbeek, M; Rimoldi, A; Rinaldi, L; Ristić, B; Ritsch, E; Riu, I; Rizatdinova, F; Rizvi, E; Robertson, S H; Robichaud-Veronneau, A; Robinson, D; Robinson, J E M; Robson, A; Roda, C; Roe, S; Røhne, O; Rolli, S; Romaniouk, A; Romano, M; Romano Saez, S M; Romero Adam, E; Rompotis, N; Ronzani, M; Roos, L; Ros, E; Rosati, S; Rosbach, K; Rose, P; Rosendahl, P L; Rosenthal, O; Rossetti, V; Rossi, E; Rossi, L P; Rosten, J H N; Rosten, R; Rotaru, M; Roth, I; Rothberg, J; Rousseau, D; Royon, C R; Rozanov, A; Rozen, Y; Ruan, X; Rubbo, F; Rubinskiy, I; Rud, V I; Rudolph, C; Rudolph, M S; Rühr, F; Ruiz-Martinez, A; Rurikova, Z; Rusakovich, N A; Ruschke, A; Russell, H L; Rutherfoord, J P; Ruthmann, N; Ryabov, Y F; Rybar, M; Rybkin, G; Ryder, N C; Saavedra, A F; Sabato, G; Sacerdoti, S; Saddique, A; Sadrozinski, H F-W; Sadykov, R; Safai Tehrani, F; Sahinsoy, M; Saimpert, M; Saito, T; Sakamoto, H; Sakurai, Y; Salamanna, G; Salamon, A; SalazarLoyola, J E; Saleem, M; Salek, D; Sales DeBruin, P H; Salihagic, D; Salnikov, A; Salt, J; Salvatore, D; Salvatore, F; Salvucci, A; Salzburger, A; Sammel, D; Sampsonidis, D; Sanchez, A; Sánchez, J; SanchezMartinez, V; Sandaker, H; Sandbach, R L; Sander, H G; Sanders, M P; Sandhoff, M; Sandoval, C; Sandstroem, R; Sankey, D P C; Sannino, M; Sansoni, A; Santoni, C; Santonico, R; Santos, H; SantoyoCastillo, I; Sapp, K; Sapronov, A; Saraiva, J G; Sarrazin, B; Sasaki, O; Sasaki, Y; Sato, K; Sauvage, G; Sauvan, E; Savage, G; Savard, P; Sawyer, C; Sawyer, L; Saxon, J; Sbarra, C; Sbrizzi, A; Scanlon, T; Scannicchio, D A; Scarcella, M; Scarfone, V; Schaarschmidt, J; Schacht, P; Schaefer, D; Schaefer, R; Schaeffer, J; Schaepe, S; Schaetzel, S; Schäfer, U; Schaffer, A C; Schaile, D; Schamberger, R D; Scharf, V; Schegelsky, V A; Scheirich, D; Schernau, M; Schiavi, C; Schillo, C; Schioppa, M; Schlenker, S; Schmieden, K; Schmitt, C; Schmitt, S; Schmitt, S; Schneider, B; Schnellbach, Y J; Schnoor, U; Schoeffel, L; Schoening, A; Schoenrock, B D; Schopf, E; Schorlemmer, A L S; Schott, M; Schouten, D; Schovancova, J; Schramm, S; Schreyer, M; Schroeder, C; Schuh, N; Schultens, M J; Schultz-Coulon, H-C; Schulz, H; Schumacher, M; Schumm, B A; Schune, Ph; Schwanenberger, C; Schwartzman, A; Schwarz, T A; Schwegler, Ph; Schweiger, H; Schwemling, Ph; Schwienhorst, R; Schwindling, J; Schwindt, T; Sciacca, F G; Scifo, E; Sciolla, G; Scuri, F; Scutti, F; Searcy, J; Sedov, G; Sedykh, E; Seema, P; Seidel, S C; Seiden, A; Seifert, F; Seixas, J M; Sekhniaidze, G; Sekhon, K; Sekula, S J; Seliverstov, D M; Semprini-Cesari, N; Serfon, C; Serin, L; Serkin, L; Serre, T; Sessa, M; Seuster, R; Severini, H; Sfiligoj, T; Sforza, F; Sfyrla, A; Shabalina, E; Shamim, M; Shan, L Y; Shang, R; Shank, J T; Shapiro, M; Shatalov, P B; Shaw, K; Shaw, S M; Shcherbakova, A; Shehu, C Y; Sherwood, P; Shi, L; Shimizu, S; Shimmin, C O; Shimojima, M; Shiyakova, M; Shmeleva, A; Shoaleh Saadi, D; Shochet, M J; Shojaii, S; Shrestha, S; Shulga, E; Shupe, M A; Shushkevich, S; Sicho, P; Sidebo, P E; Sidiropoulou, O; Sidorov, D; Sidoti, A; Siegert, F; Sijacki, Dj; Silva, J; Silver, Y; Silverstein, S B; Simak, V; Simard, O; Simic, Lj; Simion, S; Simioni, E; Simmons, B; Simon, D; Sinervo, P; Sinev, N B; Sioli, M; Siragusa, G; Sisakyan, A N; Sivoklokov, S Yu; Sjölin, J; Sjursen, T B; Skinner, M B; Skottowe, H P; Skubic, P; Slater, M; Slavicek, T; Slawinska, M; Sliwa, K; Smakhtin, V; Smart, B H; Smestad, L; Smirnov, S Yu; Smirnov, Y; Smirnova, L N; Smirnova, O; Smith, M N K; Smith, R W; Smizanska, M; Smolek, K; Snesarev, A A; Snidero, G; Snyder, S; Sobie, R; Socher, F; Soffer, A; Soh, D A; Sokhrannyi, G; Solans, C A; Solar, M; Solc, J; Soldatov, E Yu; Soldevila, U; Solodkov, A A; Soloshenko, A; Solovyanov, O V; Solovyev, V; Sommer, P; Song, H Y; Soni, N; Sood, A; Sopczak, A; Sopko, B; Sopko, V; Sorin, V; Sosa, D; Sosebee, M; Sotiropoulou, C L; Soualah, R; Soukharev, A M; South, D; Sowden, B C; Spagnolo, S; Spalla, M; Spangenberg, M; Spanò, F; Spearman, W R; Sperlich, D; Spettel, F; Spighi, R; Spigo, G; Spiller, L A; Spousta, M; Spreitzer, T; Denis, R D St; Stabile, A; Staerz, S; Stahlman, J; Stamen, R; Stamm, S; Stanecka, E; Stanescu, C; Stanescu-Bellu, M; Stanitzki, M M; Stapnes, S; Starchenko, E A; Stark, J; Staroba, P; Starovoitov, P; Staszewski, R; Steinberg, P; Stelzer, B; Stelzer, H J; Stelzer-Chilton, O; Stenzel, H; Stewart, G A; Stillings, J A; Stockton, M C; Stoebe, M; Stoicea, G; Stolte, P; Stonjek, S; Stradling, A R; Straessner, A; Stramaglia, M E; Strandberg, J; Strandberg, S; Strandlie, A; Strauss, E; Strauss, M; Strizenec, P; Ströhmer, R; Strom, D M; Stroynowski, R; Strubig, A; Stucci, S A; Stugu, B; Styles, N A; Su, D; Su, J; Subramaniam, R; Succurro, A; Sugaya, Y; Suk, M; Sulin, V V; Sultansoy, S; Sumida, T; Sun, S; Sun, X; Sundermann, J E; Suruliz, K; Susinno, G; Sutton, M R; Suzuki, S; Svatos, M; Swiatlowski, M; Sykora, I; Sykora, T; Ta, D; Taccini, C; Tackmann, K; Taenzer, J; Taffard, A; Tafirout, R; Taiblum, N; Takai, H; Takashima, R; Takeda, H; Takeshita, T; Takubo, Y; Talby, M; Talyshev, A A; Tam, J Y C; Tan, K G; Tanaka, J; Tanaka, R; Tanaka, S; Tannenwald, B B; Tannoury, N; Tapprogge, S; Tarem, S; Tarrade, F; Tartarelli, G F; Tas, P; Tasevsky, M; Tashiro, T; Tassi, E; Tavares Delgado, A; Tayalati, Y; Taylor, F E; Taylor, G N; Taylor, P T E; Taylor, W; Teischinger, F A; Teixeira Dias Castanheira, M; Teixeira-Dias, P; Temming, K K; Temple, D; Ten Kate, H; Teng, P K; Teoh, J J; Tepel, F; Terada, S; Terashi, K; Terron, J; Terzo, S; Testa, M; Teuscher, R J; Theveneaux-Pelzer, T; Thomas, J P; Thomas-Wilsker, J; Thompson, E N; Thompson, P D; Thompson, R J; Thompson, A S; Thomsen, L A; Thomson, E; Thomson, M; Thun, R P; Tibbetts, M J; TicseTorres, R E; Tikhomirov, V O; Tikhonov, Yu A; Timoshenko, S; Tiouchichine, E; Tipton, P; Tisserant, S; Todome, K; Todorov, T; Todorova-Nova, S; Tojo, J; Tokár, S; Tokushuku, K; Tollefson, K; Tolley, E; Tomlinson, L; Tomoto, M; Tompkins, L; Toms, K; Torrence, E; Torres, H; Torró Pastor, E; Toth, J; Touchard, F; Tovey, D R; Trefzger, T; Tremblet, L; Tricoli, A; Trigger, I M; Trincaz-Duvoid, S; Tripiana, M F; Trischuk, W; Trocmé, B; Troncon, C; Trottier-McDonald, M; Trovatelli, M; Truong, L; Trzebinski, M; Trzupek, A; Tsarouchas, C; Tseng, J C-L; Tsiareshka, P V; Tsionou, D; Tsipolitis, G; Tsirintanis, N; Tsiskaridze, S; Tsiskaridze, V; Tskhadadze, E G; Tsukerman, I I; Tsulaia, V; Tsuno, S; Tsybychev, D; Tudorache, A; Tudorache, V; Tuna, A N; Tupputi, S A; Turchikhin, S; Turecek, D; Turra, R; Turvey, A J; Tuts, P M; Tykhonov, A; Tylmad, M; Tyndel, M; Ueda, I; Ueno, R; Ughetto, M; Ugland, M; Ukegawa, F; Unal, G; Undrus, A; Unel, G; Ungaro, F C; Unno, Y; Unverdorben, C; Urban, J; Urquijo, P; Urrejola, P; Usai, G; Usanova, A; Vacavant, L; Vacek, V; Vachon, B; Valderanis, C; Valencic, N; Valentinetti, S; Valero, A; Valery, L; Valkar, S; Valladolid Gallego, E; Vallecorsa, S; Valls Ferrer, J A; Van Den Wollenberg, W; Van Der Deijl, P C; van der Geer, R; van der Graaf, H; van Eldik, N; van Gemmeren, P; Van Nieuwkoop, J; van Vulpen, I; van Woerden, M C; Vanadia, M; Vandelli, W; Vanguri, R; Vaniachine, A; Vannucci, F; Vardanyan, G; Vari, R; Varnes, E W; Varol, T; Varouchas, D; Vartapetian, A; Varvell, K E; Vazeille, F; Vazquez Schroeder, T; Veatch, J; Veloce, L M; Veloso, F; Velz, T; Veneziano, S; Ventura, A; Ventura, D; Venturi, M; Venturi, N; Venturini, A; Vercesi, V; Verducci, M; Verkerke, W; Vermeulen, J C; Vest, A; Vetterli, M C; Viazlo, O; Vichou, I; Vickey, T; VickeyBoeriu, O E; Viehhauser, G H A; Viel, S; Vigne, R; Villa, M; Villaplana Perez, M; Vilucchi, E; Vincter, M G; Vinogradov, V B; Vivarelli, I; Vives Vaque, F; Vlachos, S; Vladoiu, D; Vlasak, M; Vogel, M; Vokac, P; Volpi, G; Volpi, M; von der Schmitt, H; von Radziewski, H; von Toerne, E; Vorobel, V; Vorobev, K; Vos, M; Voss, R; Vossebeld, J H; Vranjes, N; Vranjes Milosavljevic, M; Vrba, V; Vreeswijk, M; Vuillermet, R; Vukotic, I; Vykydal, Z; Wagner, P; Wagner, W; Wahlberg, H; Wahrmund, S; Wakabayashi, J; Walder, J; Walker, R; Walkowiak, W; Wang, C; Wang, F; Wang, H; Wang, H; Wang, J; Wang, J; Wang, K; Wang, R; Wang, S M; Wang, T; Wang, T; Wang, X; Wanotayaroj, C; Warburton, A; Ward, C P; Wardrope, D R; Washbrook, A; Wasicki, C; Watkins, P M; Watson, A T; Watson, I J; Watson, M F; Watts, G; Watts, S; Waugh, B M; Webb, S; Weber, M S; Weber, S W; Webster, J S; Weidberg, A R; Weinert, B; Weingarten, J; Weiser, C; Weits, H; Wells, P S; Wenaus, T; Wengler, T; Wenig, S; Wermes, N; Werner, M; Werner, P; Wessels, M; Wetter, J; Whalen, K; Wharton, A M; White, A; White, M J; White, R; White, S; Whiteson, D; Wickens, F J; Wiedenmann, W; Wielers, M; Wienemann, P; Wiglesworth, C; Wiik-Fuchs, L A M; Wildauer, A; Wilkens, H G; Williams, H H; Williams, S; Willis, C; Willocq, S; Wilson, A; Wilson, J A; Wingerter-Seez, I; Winklmeier, F; Winter, B T; Wittgen, M; Wittkowski, J; Wollstadt, S J; Wolter, M W; Wolters, H; Wosiek, B K; Wotschack, J; Woudstra, M J; Wozniak, K W; Wu, M; Wu, M; Wu, S L; Wu, X; Wu, Y; Wyatt, T R; Wynne, B M; Xella, S; Xu, D; Xu, L; Yabsley, B; Yacoob, S; Yakabe, R; Yamada, M; Yamaguchi, D; Yamaguchi, Y; Yamamoto, A; Yamamoto, S; Yamanaka, T; Yamauchi, K; Yamazaki, Y; Yan, Z; Yang, H; Yang, H; Yang, Y; Yao, W-M; Yasu, Y; Yatsenko, E; Yau Wong, K H; Ye, J; Ye, S; Yeletskikh, I; Yen, A L; Yildirim, E; Yorita, K; Yoshida, R; Yoshihara, K; Young, C; Young, C J S; Youssef, S; Yu, D R; Yu, J; Yu, J M; Yu, J; Yuan, L; Yuen, S P Y; Yurkewicz, A; Yusuff, I; Zabinski, B; Zaidan, R; Zaitsev, A M; Zalieckas, J; Zaman, A; Zambito, S; Zanello, L; Zanzi, D; Zeitnitz, C; Zeman, M; Zemla, A; Zeng, Q; Zengel, K; Zenin, O; Ženiš, T; Zerwas, D; Zhang, D; Zhang, F; Zhang, H; Zhang, J; Zhang, L; Zhang, R; Zhang, X; Zhang, Z; Zhao, X; Zhao, Y; Zhao, Z; Zhemchugov, A; Zhong, J; Zhou, B; Zhou, C; Zhou, L; Zhou, L; Zhou, M; Zhou, N; Zhu, C G; Zhu, H; Zhu, J; Zhu, Y; Zhuang, X; Zhukov, K; Zibell, A; Zieminska, D; Zimine, N I; Zimmermann, C; Zimmermann, S; Zinonos, Z; Zinser, M; Ziolkowski, M; Živković, L; Zobernig, G; Zoccoli, A; Zur Nedden, M; Zurzolo, G; Zwalinski, L

Searches for pair-produced scalar leptoquarks are performed using 20 fb[Formula: see text] of proton-proton collision data provided by the LHC and recorded by the ATLAS detector at [Formula: see text] TeV. Events with two electrons (muons) and two or more jets in the final state are used to search for first (second)-generation leptoquarks. The results from two previously published ATLAS analyses are interpreted in terms of third-generation leptoquarks decaying to [Formula: see text] and [Formula: see text] final states. No statistically significant excess above the Standard Model expectation is observed in any channel and scalar leptoquarks are excluded at 95 % CL with masses up to [Formula: see text] 1050 GeV for first-generation leptoquarks, [Formula: see text] 1000 GeV for second-generation leptoquarks, [Formula: see text] 625 GeV for third-generation leptoquarks in the [Formula: see text] channel, and 200 [Formula: see text] 640 GeV in the [Formula: see text] channel.

Electrical and structural properties of group-4 transition-metal nitride (TiN, ZrN, and HfN) contacts on Ge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, Keisuke; Nakashima, Hiroshi, E-mail: nakasima@astec.kyushu-u.ac.jp; Noguchi, Ryutaro

2015-09-21

Electrical and structural properties were investigated for group-4 transition-metal nitride contacts on Ge (TiN/Ge, ZrN/Ge, and HfN/Ge), which were prepared by direct sputter depositions using nitride targets. These contacts could alleviate the intrinsic Fermi-level pinning (FLP) position toward the conduction band edge. It was revealed that this phenomenon is induced by an amorphous interlayer (a-IL) containing nitrogen atoms at the nitride/Ge interfaces. The strength of FLP alleviation positively depended on the thickness of a-IL. TiN/Ge and ZrN/Ge contacts with ∼2 nm-thick a-ILs showed strong FLP alleviations with hole barrier heights (Φ{sub BP}) in the range of 0.52–56 eV, and a HfN/Ge contactmore » with an ∼1 nm-thick a-IL showed a weaker one with a Φ{sub BP} of 0.39 eV. However, TaN/Ge contact without a-IL did not show such FLP alleviation. Based on the results of depth distributions for respective elements, we discussed the formation kinetics of a-ILs at TiN/Ge and ZrN/Ge interfaces. Finally, we proposed an interfacial dipole model to explain the FLP alleviation.« less

The promise of solution-processed Fe 2GeS 4 thin films in iron chalcogenide photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Mimi; Berg, Dominik M.; Hwang, Po-Yu

The olivine Fe 2GeS 4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe 2GeS 4 precursor powders obtained via a simple solution-based process were converted to highly crystalline Fe 2GeS 4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe 2GeS 4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe 2GeS 4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe 2GeS 4 thin films as the sole absorber in a solution-based solarmore » cell, open-circuit voltages of 361 mV are observed, while the use of the Fe 2GeS 4 films as counter electrodes in dye-sensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. Finally, this is the first report of a photovoltaic device based onFe 2GeS 4.« less

The promise of solution-processed Fe 2GeS 4 thin films in iron chalcogenide photovoltaics

DOE PAGES

Liu, Mimi; Berg, Dominik M.; Hwang, Po-Yu; ...

2018-02-06

The olivine Fe 2GeS 4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe 2GeS 4 precursor powders obtained via a simple solution-based process were converted to highly crystalline Fe 2GeS 4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe 2GeS 4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe 2GeS 4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe 2GeS 4 thin films as the sole absorber in a solution-based solarmore » cell, open-circuit voltages of 361 mV are observed, while the use of the Fe 2GeS 4 films as counter electrodes in dye-sensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. Finally, this is the first report of a photovoltaic device based onFe 2GeS 4.« less

Enhanced stability of Bi-doped Ge2Sb2Te5 amorphous films

NASA Astrophysics Data System (ADS)

Dyussembayev, S.; Prikhodko, O.; Tsendin, K.; Timoshenkov, S.; Korobova, N.

2014-09-01

Although, several reviews have appeared on various physical properties and applications of chalcogenide glasses, there is no thorough study of local atomic structure and its modification for eutectic Ge-Sb-Te alloys doped with Bi. Ge2Sb2Te5 pure and Bi-doped films were deposited by ion-plasma sputtering method of synthesized GTS material on Si (100) and glass substrates coated with a conductive Al layer which was used as a bottom electrode. Current-voltage characteristics of different points of the same samples have been measured. Random distribution of inclusions within the sample made it possible to investigate the dependence of switching and memory effects on the phase composition at a constant value of other parameters. Measurements in the current controlled mode clearly showed that the memory state formation voltage does not depend on current in a wide range. Results indicate that the development of imaging technologies phase memory cells need to pay special attention to the conditions of Ge-Sb-Te film preparation. To increase the number of cycles "write - erase" should be additional prolonged annealing of the synthesized films.

Thermoelectric Properties of Nanograined Si-Ge-Au Thin Films Grown by Molecular Beam Deposition

NASA Astrophysics Data System (ADS)

Nishino, Shunsuke; Ekino, Satoshi; Inukai, Manabu; Omprakash, Muthusamy; Adachi, Masahiro; Kiyama, Makoto; Yamamoto, Yoshiyuki; Takeuchi, Tsunehiro

2018-06-01

Conditions to achieve extremely large Seebeck coefficient and extremely small thermal conductivity in Si-Ge-Au thin films formed of nanosized grains precipitated in amorphous matrix have been investigated. We employed molecular beam deposition to prepare Si1- x Ge x Au y thin films on sapphire substrate. The deposited films were annealed under nitrogen gas atmosphere at 300°C to 500°C for 15 min to 30 min. Nanocrystals dispersed in amorphous matrix were clearly observed by transmission electron microscopy. We did not observe anomalously large Seebeck coefficient, but very low thermal conductivity of nearly 1.0 W K-1 m-1 was found at around 0.2 < x < 0.6. The compositional dependence of the thermal conductivity was well accounted for by the compositional dependence of the mixing entropy. Some of these values agree exactly with the amorphous limit predicted by theoretical calculations. The smallest lattice thermal conductivity found for the present samples is lower than that of nanostructured Si-Ge bulk material for which dimensionless figure of merit of ZT ≈ 1 was reported at high temperature.

Low thermal budget n-type doping into Ge(001) surface using ultraviolet laser irradiation in phosphoric acid solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Kouta, E-mail: ktakahas@alice.xtal.nagoya-u.ac.jp, E-mail: kurosawa@alice.xtal.nagoya-u.ac.jp; Sakashita, Mitsuo; Takeuchi, Wakana

2016-02-01

We have investigated phosphorus (P) doping into Ge(001) surfaces by using ultraviolet laser irradiation in phosphoric acid solution at room temperature. We demonstrated that the diffusion depth of P in Ge and the concentration of electrically activated P can be controlled by the number of laser shots. Indeed, a high concentration of electrically activated P of 2.4 × 10{sup 19} cm{sup −3} was realized by 1000-times laser shots at a laser energy of 1.0 J/cm{sup 2}, which is comparable or better than the counterparts of conventional n-type doping using a high thermal budget over 600 °C. The generation current is dominant in the reverse biasmore » condition for the laser-doped pn-junction diodes independent on the number of laser shots, thus indicating low-damage during the pn-junction formation. These results open up the possibility for applicable low thermal budget doping process for Ge-based devices fabricated on flexible substrates as well as Si electronics.« less

Si(111) strained layers on Ge(111): Evidence for c (2 ×4 ) domains

NASA Astrophysics Data System (ADS)

Zhachuk, R.; Coutinho, J.; Dolbak, A.; Cherepanov, V.; Voigtländer, B.

2017-08-01

The tensile-strained Si (111 ) layers grown on top of Ge (111 ) substrates are studied by combining scanning tunneling microscopy, low-energy electron diffraction, and first-principles calculations. It is shown that the layers exhibit c (2 ×4 ) domains, which are separated by domain walls along <1 ¯10 > directions. A model structure for the c (2 ×4 ) domains is proposed, which shows low formation energy and good agreement with the experimental data. The results of our calculations suggest that Ge atoms are likely to replace Si atoms with dangling bonds on the surface (rest-atoms and adatoms), thus significantly lowering the surface energy and inducing the formation of domain walls. The experiments and calculations demonstrate that when surface strain changes from compressive to tensile, the (111) reconstruction converts from dimer-adatom-stacking fault-based to adatom-based structures.

Characterization of a Hierarchical Network of Hyaluronic Acid/Gelatin Composite for use as a Smart Injectable Biomaterial

PubMed Central

Heris, Hossein K.; Rahmat, Meysam

2015-01-01

Hybrid HA/Ge hydrogel particles are embedded in a secondary HA network to improve their structural integrity. The internal microstructure of the particles is imaged through TEM. CSLM is used to identify the location of the Ge molecules in the microgels. Through indentation tests, the Young’s modulus of the individual particles is found to be 22 ± 2.5 kPa. The overall shear modulus of the composite is 75 ± 15 Pa at 1 Hz. The mechanical properties of the substrate are found to be viable for cell adhesion. The particles’ diameter at pH = 8 is twice that at pH = 5. The pH sensitivity is found to be appropriate for smart drug delivery. Based on their mechanical and structural properties, HA–Ge hierarchical materials may be well suited for use as injectable biomaterials for tissue reconstruction. PMID:22147507

Growth of well-aligned ZnO nanorods using auge catalyst by vapor phase transportation.

PubMed

Ha, S Y; Jung, M N; Park, S H; Ko, H J; Ko, H; Oh, D C; Yao, T; Chang, J H

2006-11-01

Well-aligned ZnO nanorods have been achieved using new alloy (AuGe) catalyst. Zn powder was used as a source material and it was transported in a horizontal tube furnace onto an AuGe deposited Si substrates. The structural and optical properties of ZnO nanorods were characterized by scanning electron microscopy, high resolution X-ray diffraction, and photoluminescence. ZnO nanorods grown at 650 degrees C on 53 nm thick AuGe layer show uniform shape with the length of 8 +/- 0.5 microm and the diameter of 150 +/- 5 nm. Also, the tilting angle of ZnO nanorods (+/- 5.5 degrees) is confirmed by HRXRD. High structural quality of the nanorods is conformed by the photoluminescence measurement. All samples show strong UV emission without considerable deep level emission. However, weak deep level emission appears at high (700 degrees C) temperature due to the increase of oxygen desertion.

Nano-electron beam induced current and hole charge dynamics through uncapped Ge nanocrystals

NASA Astrophysics Data System (ADS)

Marchand, A.; El Hdiy, A.; Troyon, M.; Amiard, G.; Ronda, A.; Berbezier, I.

2012-04-01

Dynamics of hole storage in spherical Ge nanocrystals (NCs) formed by a two step dewetting/nucleation process on an oxide layer grown on an n-doped <001> silicon substrate is studied using a nano-electron beam induced current technique. Carrier generation is produced by an electron beam irradiation. The generated current is collected by an atomic force microscope—tip in contact mode at a fixed position away from the beam spot of about 0.5 µm. This distance represents the effective diffusion length of holes. The time constants of holes charging are determined and the effect of the NC size is underlined.

From the 750 GeV diphoton resonance to multilepton excesses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, Kyu Jung; Chen, Chuan-Ren; Hamaguchi, Koichi

2016-07-01

Weakly coupled models for the 750 GeV diphoton resonance often invoke new particles carrying both color and/or electric charges to mediate loop-induced couplings of the resonance to two gluons and two photons. The new colored particles may not be stable and could decay into final states containing standard model particles. We consider an electroweak doublet of vectorlike quarks (VLQs) carrying electric charges of 5/3 and 2/3, respectively, which mediate the loop-induced couplings of the 750 GeV resonance. If the VLQ has a mass at around 1 TeV, it naturally gives rise to the observed diphoton signal strength while all couplingsmore » remain perturbative up to a high scale. At the same time, if the charge-5/3 VLQ decays into final states containing top quark and W boson, it would contribute to the multilepton excesses observed in both run 1 and run 2 data. It is also possible to incorporate a dark matter candidate in the decay final states to explain the observed relic density.« less

Search for new resonances in Wγ and Zγ final states in pp collisions at √ s = 8 TeV with the ATLAS detector

DOE PAGES

Aad, G.

2014-10-06

This Letter presents a search for new resonances decaying to final states with a vector boson produced in association with a high transverse momentum photon, Vγ , with V=W(→ℓν) or Z(→ℓ +ℓ -), where ℓ=e or μ. The measurements use 20.3 fb -1 of proton–proton collision data at a center-of-mass energy of √s = 8 TeV recorded with the ATLAS detector. No deviations from the Standard Model expectations are found, and production cross section limits are set at 95% confidence level. Masses of the hypothetical aT and ω T states of a benchmark Low Scale Technicolor model are excluded inmore » the ranges [275,960] GeV and [200,700]υ[750,890] GeV, respectively. Limits at 95% confidence level on the production cross section of a singlet scalar resonance decaying to Zγ final states have also been obtained for masses below 1180 GeV.« less

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √s = 8 TeV with the ATLAS detector

DOE PAGES

Aad, G.

2015-07-01

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb -1 of \\(\\sqrt{s{\\mathrm{}}} = 8\\) TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with p T>120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between E miss T>150 GeV and E miss T>700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. Results are translated into exclusionmore » limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presented.« less

Adjusting the surface areal density of click-reactive azide groups by kinetic control of the azide substitution reaction on bromine-functional SAMs.

PubMed

Zhang, Shuo; Maidenberg, Yanir; Luo, Kai; Koberstein, Jeffrey T

2014-06-03

Azide-alkyne click chemistry has emerged as an important and versatile means for tethering a wide variety of guest molecules to virtually any substrate. In many of these applications, it is important to exercise control over the areal density of surface functional groups to achieve a desired areal density of the tethered guest molecule of interest. We demonstrate herein that the areal density of surface azide groups on flat germanium surfaces and nanoparticle substrates (silica and iron oxide) can be controlled kinetically by appropriately timed quenching of the S(N)2 substitution reaction of bromo-alkane-silane monolayers induced by the addition of sodium azide. The kinetics of the azide substitution reaction on monolayers formed on flat Ge substrates, determined by attenuated total reflection infrared spectroscopy (ATR-IR), are found to be identical to those for monolayers formed on both silica and iron oxide nanoparticles, the latter determined by transmission infrared spectroscopy. To validate the method, the percentages of surface bromine groups converted to azide groups after various reaction times were measured by quenching the S(N)2 reaction followed by analysis with ATR-IR (for Ge) and thermogravimetric analysis (after a subsequent click reaction with an alkyne-terminal polymer) for the nanoparticle substrates. The conversions found after quenching agree well with those expected from the standard kinetic curves. The latter result suggests that the kinetic method for the control of azide group areal density is a versatile means for functionalizing substrates with a prescribed areal density of azide groups for subsequent click reactions, and that the method is universal for any substrate, flat or nanoparticle, that can be modified with bromo-alkane-silane monolayers. Regardless of the surface geometry, we find that the azide substitution reaction is complete within 2-3 h, in sharp contrast to previous reports that indicate times of 48-60 h required for completion of the reaction.