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1

Surface-charge measurements in microgap dielectric barrier discharge using bismuth silicon oxide crystals  

NASA Astrophysics Data System (ADS)

A surface-charge measurement system based on the Pockels effect in bismuth silicon oxide dielectric crystals was constructed for measuring the surface-charge density of the dielectrics in the microgap dielectric barrier discharge. We re-examined the calculation methods of the surface-charge density from the voltage applied to the BSO crystal, obtained by laser interferometry. The charge calculated using the circuit equation coincided with the that obtained using the discharge current. Under certain experimental conditions, the maximum values of the surface charge density in the discharge cell with and without a protection glass were +2.0 and +2.5 nC/cm2, respectively.

Mukaigawa, S.; Matsuda, H.; Fue, H.; Takahashi, R.; Takaki, K.; Fujiwara, T.

2013-06-01

2

Transport study of a single bismuth nanowire fabricated by the silver and silicon nanowire shadow masks  

E-print Network

Transport study of a single bismuth nanowire fabricated by the silver and silicon nanowire shadow bismuth nanowires fabricated by the low energy electron beam lithography using the silver/silicon nanowire of the electrical conductivity of a bismuth nanowire, which is strikingly different from that of the bulk bismuth

3

Bismuth based oxide electrolytes— structure and ionic conductivity  

Microsoft Academic Search

Bismuth oxide systems exhibit high oxide ion conductivity and have been proposed as good electrolyte materials for applications such as solid oxide fuel cells and oxygen sensors. However, due to their instability under conditions of low oxygen partial pressures there has been difficulty in developing these materials as alternative electrolyte materials compared to the state-of-the-art cubic stabilised zirconia electrolyte. Bismuth

N. M. Sammes; G. A. Tompsett; H. Näfe; F. Aldinger

1999-01-01

4

Optical and electrical properties of thermally oxidized bismuth thin films  

Microsoft Academic Search

Bismuth trioxide (Bi2O3) thin films were prepared by dry thermal oxidation of metallic bismuth films deposited by vacuum evaporation. The oxidation process of Bi films consists of a heating from the room temperature to an oxidation temperature (To=673K), with a temperature rate of 8K\\/min; an annealing for 1h at oxidation temperature and, finally, a cooling to room temperature. The optical

S. Condurache-Bota; N. Tigau; A. P. Rambu; G. G. Rusu; G. I. Rusu

2011-01-01

5

Barium Titanate and Bismuth Oxide Nanocomposites Barium titanate, BaTiO3, and bismuth oxide Bi2O3 are transparent materials with  

E-print Network

Barium Titanate and Bismuth Oxide Nanocomposites Barium titanate, BaTiO3, and bismuth oxide Bi2O3 Wall in Tetragonal Barium Titanate", H. Chaib, F. Schlaphof, T. Otto and L. M. Eng, Journal of Physics

Harmon, Julie P.

6

Buried oxide layer in silicon  

DOEpatents

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir, TN)

2001-01-01

7

Mullite interaction with bismuth oxide from minerals and sol-gel processes F. Gridi-Bennadji *  

E-print Network

Mullite interaction with bismuth oxide from minerals and sol-gel processes F. Gridi-Bennadji * , J doped by bismuth oxide was studied by TGA and DTA, X ray diffraction, and electron microscopy (SEM muscovite. With addition of bismuth oxide, SEM observations point to the strong accentuation of mullite

Paris-Sud XI, Université de

8

Bismuth in silicon qubits: the role of EPR cancellation resonances  

E-print Network

We investigate theoretically and experimentally the electron paramagnetic resonance (EPR) spectra of bismuth doped silicon (Si:Bi) at intermediate magnetic fields, $B \\approx 0.05 -0.6$ T. We identify a previously unexplored EPR regime of "cancellation-resonances"- where part of the hyperfine coupling is resonant with the external field-induced splitting. We show this regime has interesting and experimentally accessible consequences for spectroscopy and quantum information applications. These include reduction of decoherence, fast manipulation of the coupled nuclear-electron qubit system and line narrowing in the multi-qubit case. We test our theoretical analysis by comparing with experimental X-band (9.7 GHz) EPR spectra obtained in the intermediate field regime.

M. H. Mohammady; G. W. Morley; T. S. Monteiro

2010-08-25

9

Bismuth qubits in silicon: the role of EPR "cancellation resonances"  

E-print Network

We investigate theoretically and experimentally the electron paramagnetic resonance (EPR) spectra of bismuth doped silicon (Si:Bi) at intermediate magnetic fields, $B \\approx 0.05 -0.6$ T. We identify a previously unexplored EPR regime of "cancellation-resonances"- where the non-isotropic part of $ AS_zI_z$, the Ising part of the hyperfine coupling, is resonant with the external field-induced splitting. We show this regime has interesting and experimentally accessible consequences for spectroscopy and quantum information applications. These include reduction of decoherence, faster manipulation of the coupled nuclear-electron qubit system and line narrowing in the multi-qubit case. We test our theoretical analysis by comparing with experimental X-band (9.7 GHz) EPR spectra obtained in the intermediate field regime.

Mohammady, M H; Monteiro, T S

2010-01-01

10

METHOD OF PREPARING URANIUM, THORIUM, OR PLUTONIUM OXIDES IN LIQUID BISMUTH  

Microsoft Academic Search

A method is given for forming compositions, as well as the compositions ; themselves, employing uranium hydride in a liquid bismuth composition to increase ; the solubility of uranium, plutonium and thorium oxides in the liquid bismuth. ; The finely divided oxide of uranium, plutonium. or thorium is mixed with the ; liquid bismuth and uranium hydride, the hydride being

J. K. Davidson; W. L. Robb; O. N. Salmon

1960-01-01

11

Bismuth Spheres Grown in Self-Nested Cavities in a Silicon Hong Liu, and Zhong Lin Wang*,  

E-print Network

Bismuth Spheres Grown in Self-Nested Cavities in a Silicon Wafer Hong Liu, and Zhong Lin Wang-step, hydrofluoric acid-free hydrothermal etching method that not only produces bismuth nano/micrometer-sized spheres Bismuth is a semimetal with unusual electronic properties that results from its highly anisotropic Fermi

Wang, Zhong L.

12

Optical and electrical properties of thermally oxidized bismuth thin films  

NASA Astrophysics Data System (ADS)

Bismuth trioxide (Bi 2O 3) thin films were prepared by dry thermal oxidation of metallic bismuth films deposited by vacuum evaporation. The oxidation process of Bi films consists of a heating from the room temperature to an oxidation temperature ( To = 673 K), with a temperature rate of 8 K/min; an annealing for 1 h at oxidation temperature and, finally, a cooling to room temperature. The optical transmission and reflection spectra of the films were studied in spectral domains ranged between 300 nm and 1700 nm, for the transmission coefficient, and between 380 nm and 1050 nm for the reflection coefficient, respectively. The thin-film surface structures of the metal/oxide/metal type were used for the study of the static current-voltage ( I- U) characteristics. The temperature of the substrate during bismuth deposition strongly influences both the optical and the electrical properties of the oxidized films. For lower values of intensity of electric field ( ? < 5 × 10 4V/cm), I- U characteristics are ohmic.

Condurache-Bota, S.; Tigau, N.; Rambu, A. P.; Rusu, G. G.; Rusu, G. I.

2011-10-01

13

Bismuth-based oxide semiconductors: Mild synthesis and practical applications  

NASA Astrophysics Data System (ADS)

In this dissertation study, bismuth based oxide semiconductors were prepared using 'mild' synthesis techniques---electrodeposition and solution combustion synthesis. Potential environmental remediation and solar energy applications of the prepared oxides were evaluated. Bismuth vanadate (BiVO4) was prepared by electrodeposition and solution combustion synthesis. A two step electrosynthesis strategy was developed and demonstrated for the first time. In the first step, a Bi film was first electrodeposited on a Pt substrate from an acidic BiCl3 medium. Then, this film was anodically stripped in a medium containing hydrolyzed vanadium precursor, to generate Bi3+, and subsequent BiVO4 formation by in situ precipitation. The photoelectrochemical data were consistent with the in situ formation of n-type semiconductor films. In the solution combustion synthesis procedure, BiVO4 powders were prepared using bismuth nitrate pentahydrate as the bismuth precursor and either vanadium chloride or vanadium oxysulfate as the vanadium precursor. Urea, glycine, or citric acid was used as the fuel. The effect of the vanadium precursor on the photocatalytic activity of combustion synthesized BiVO 4 was evaluated in this study. Methyl orange was used as a probe to test the photocatalytic attributes of the combustion synthesized (CS) samples, and benchmarked against a commercial bismuth vanadate sample. The CS samples showed superior activity to the commercial benchmark sample, and samples derived from vanadium chloride were superior to vanadium oxysulfate counterparts. The photoelectrochemical properties of the various CS samples were also studied and these samples were shown to be useful both for environmental photocatalytic remediation and water photooxidation applications. Silver bismuth tungstate (AgBiW2O8) nanoparticles were prepared for the first time by solution combustion synthesis by using silver nitrate, bismuth nitrate, sodium tungstate as precursors for Ag, Bi, and W respectively and urea as the fuel. The photocatalytic activity of these nanoparticles was superior to a sample prepared by solid-state synthesis. The combustion-synthesized particles were subsequently modified with Pt catalyst islands using a photodeposition technique and then used for the photo-generation of syngas (CO + H2). Formic acid was used in these experiments for in situ generation of CO2 and its subsequent reduction to CO. In the absence of Pt modification, H2 was not obtained. These results were compared with those obtained with acetic acid in place of formic acid, and finally the mechanistic pathways for syngas and methane photogeneration are presented.

Timmaji, Hari Krishna

14

Oxidation resistance of silicon ceramics  

NASA Technical Reports Server (NTRS)

Oxidation resistance, and examples of oxidation of SiC, Si3N4 and sialon are reviewed. A description is given of the oxidation mechanism, including the oxidation product, oxidation reaction and the bubble size. The oxidation reactions are represented graphically. An assessment is made of the oxidation process, and an oxidation example of silicon ceramics is given.

Yasutoshi, H.; Hirota, K.

1984-01-01

15

Bismuth oxide nanotubes-graphene fiber-based flexible supercapacitors  

NASA Astrophysics Data System (ADS)

Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics.Graphene-bismuth oxide nanotube fiber as electrode material for constituting flexible supercapacitors using a PVA/H3PO4 gel electrolyte is reported with a high specific capacitance (Ca) of 69.3 mF cm-2 (for a single electrode) and 17.3 mF cm-2 (for the whole device) at 0.1 mA cm-2, respectively. Our approach opens the door to metal oxide-graphene hybrid fibers and high-performance flexible electronics. Electronic supplementary information (ESI) available: Equations and characterization. SEM images of GGO, XRD and XPS of Bi2O3 NTs, HRTEM images and EDX Spectra of Bi2O3 NT5-GF, CV curves of Bi2O3NT5-GF, Bi2O3 NTs and bismuth nitrate in three-electrode system (vs. Ag/AgCl). CV and GCD curves of Bi2O3 NT1-GF and Bi2O3 NT3-GF. See DOI: 10.1039/c4nr02615b

Gopalsamy, Karthikeyan; Xu, Zhen; Zheng, Bingna; Huang, Tieqi; Kou, Liang; Zhao, Xiaoli; Gao, Chao

2014-07-01

16

On the Refinement Mechanism of Silicon in Al-Si-Cu-Zn Alloy with Addition of Bismuth  

NASA Astrophysics Data System (ADS)

Obtained results of micro and nano studies reveal that bismuth refines the silicon in which the flake silicon changed to lamellar structure with reduction in twin spacing from 160 to 75 nm. Bismuth segregates towards the inter-dendritic regions and decreases the Al-Si contact angle resulting in suppression of the silicon growth causing refinement of the eutectic structure. Increased recalescence temperature and time confirmed that the refinement effect is attributed to the growth stage.

Farahany, Saeed; Ourdjini, Ali; Bakar, Tuty Asma Abu; Idris, Mohd Hasbullah

2014-01-01

17

Bismuth Oxide Nanoparticles in the Stratosphere  

NASA Technical Reports Server (NTRS)

Platey grains of cubic Bi2O3, alpha-Bi2O3, and Bi2O(2.75), nanograins were associated with chondritic porous interplanetary dust particles W7029C1, W7029E5, and 2011C2 that were collected in the stratosphere at 17-19 km altitude. Similar Bi oxide nanograins were present in the upper stratosphere during May 1985. These grains are linked to the plumes of several major volcanic eruptions during the early 1980s that injected material into the stratosphere. The mass of sulfur from these eruptions is a proxy for the mass of stratospheric Bi from which we derive the particle number densities (p/cu m) for "average Bi2O3 nanograins" due to this volcanic activity and those necessary to contaminate the extraterrestrial chondritic porous interplanetary dust particles via collisional sticking. The match between both values supports the idea that Bi2O3 nanograins of volcanic origin could contaminate interplanetary dust particles in the Earth's stratosphere.

Rietmeijer, Frans J. M.; Mackinnon, Ian D. R.

1997-01-01

18

Guided photoluminescence study ofNd-doped Silicon Rich Silicon Oxide and Silicon Rich Silicon Nitride waveguides  

E-print Network

Guided photoluminescence study ofNd-doped Silicon Rich Silicon Oxide and Silicon Rich Silicon Abstract: Planar waveguides made of Nd3+ -doped silicon rich silicon oxide (SRSO) and silicon rich silicon on silicon nitride planar waveguide for a sample length superior to 1.5 cm. The guided fluorescence decays

Paris-Sud XI, Université de

19

Energetics of disordered and ordered rare earth oxide-stabilized bismuth oxide ionic conductors.  

PubMed

Rare-earth stabilized bismuth oxides are known for their excellent ionic conductivity at intermediate temperatures. However, previous studies have shown that their conductivity deteriorates during extended heat treatments at 500-600 °C, although the fluorite phase is maintained. In this study, the enthalpies of formation of quenched and aged ytterbia- and dysprosia-stabilized bismuth oxides were measured using high-temperature oxide melt solution calorimetry in 3Na2O-4MoO3 solvent at 702 °C. While a modest energy difference (-2 to -3 kJ mol(-1)) drives the kinetically slow aging transformation in the ytterbia-stabilized system at moderate dopant contents, no energetic driving force is detectable in the dysprosia-stabilized system. Although the small magnitude of the exothermic ordering energy suggests extensive short range ordering in both the quenched and aged samples, the anion configuration specific to the aged samples is nevertheless responsible for the significant decrease in conductivity. PMID:24346653

Tran, Tien B; Navrotsky, Alexandra

2014-02-14

20

Structure and resistivity of bismuth nanobelts in situ synthesized on silicon wafer through an ethanol-thermal method  

SciTech Connect

Bismuth nanobelts in situ grown on a silicon wafer were synthesized through an ethanol-thermal method without any capping agent. The structure of the bismuth belt-silicon composite nanostructure was characterized by scanning electron microscope, energy-dispersive X-ray spectroscopy, and high resolution transmission electron microscope. The nanobelt is a multilayered structure 100-800 nm in width and over 50 {mu}m in length. One layer has a thickness of about 50 nm. A unique sword-like nanostructure is observed as the initial structure of the nanobelts. From these observations, a possible growth mechanism of the nanobelt is proposed. Current-voltage property measurements indicate that the resistivity of the nanobelts is slightly larger than that of the bulk bismuth material. - Graphical Abstract: TEM images, EDS, and electron diffraction pattern of bismuth nanobelts. Highlights: Black-Right-Pointing-Pointer Bismuth nanobelts in situ grown on silicon wafer were achieved. Black-Right-Pointing-Pointer Special bismuth-silicon nanostructure. Black-Right-Pointing-Pointer Potential application in sensitive magnetic sensor and other electronic devices.

Gao Zheng; Qin Haiming; Yan Tao [State Key Laboratory of Crystal Materials, Bio-Micro/Nano Functional Materials Center, Shandong University, Jinan 250100 (China); Liu Hong, E-mail: hongliu@sdu.edu.cn [State Key Laboratory of Crystal Materials, Bio-Micro/Nano Functional Materials Center, Shandong University, Jinan 250100 (China); Wang Jiyang [State Key Laboratory of Crystal Materials, Bio-Micro/Nano Functional Materials Center, Shandong University, Jinan 250100 (China)

2011-12-15

21

Morphology modulated growth of bismuth tungsten oxide nanocrystals  

SciTech Connect

Two kinds of bismuth tungsten oxide nanocrystals were prepared by microwave hydrothermal method. The morphology modulation of nanocrystals synthesized with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi{sub 2}WO{sub 6} nanoflakes was synthesized in acid precursor suspension and the nanooctahedron crystals of Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were synthesized in alkalescent precursor. The dominant crystal is changed from Bi{sub 2}WO{sub 6} to Bi{sub 3.84}W{sub 0.16}O{sub 6.24} when the precursor suspension changes from acid to alkalescence. The growth mechanisms of Bi{sub 2}WO{sub 6} and Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were attributed to the different solubility of WO{sub 4}{sup 2-} and [Bi{sub 2}O{sub 2}]{sup 2+} in precursor suspensions with various pH. For the decomposition of Rhodamine B (RhB) under visible light irradiation ({lambda}>400 nm), different morphology of Bi{sub 2}WO{sub 6} crystal samples obtained by microwavesolvothermal process showed different photocatalytic activity. - Graphical abstract: The morphology modulation of bismuth tungsten oxide nanocrystals synthesized by microwave hydrothermal method with precursor suspension's pH varied from 0.25 (strong acid) to 10.05 (base) was studied. The 3D flower like aggregation of Bi{sub 2}WO{sub 6} nanoflakes and nanooctahedron crystals of Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were prepared. The growth mechanisms of Bi{sub 2}WO{sub 6} and Bi{sub 3.84}W{sub 0.16}O{sub 6.24} were attributed to the different precipitation ability and solubility of H{sub 2}WO{sub 4} and Bi(OH){sub 3} in precursor suspensions with various pH. The photocatalytic evaluation, via the decomposition of Rhodamine B (RhB) under visible light irradiation ({lambda}>420 nm), reveals that nanocrystalline Bi{sub 2}WO{sub 6} samples obtained in different condition exhibit different photocatalytic activities which depend on pH value of the precursor suspensions.

Yao Shushan [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China); Wei, Jiyong [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China); Chemistry and Chemical Engineering College, Shandong University, Jinan 250100 (China); Huang Baibiao [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China)], E-mail: bbhuang@sdu.edu.cn; Feng Shengyu [Chemistry and Chemical Engineering College, Shandong University, Jinan 250100 (China); Zhang Xiaoyang; Qin Xiaoyan; Wang Peng; Wang Zeyan; Zhang Qi; Jing Xiangyang; Zhan Jie [State Key Lab of Crystal Materials, Shandong University, Jinan 250100 (China)

2009-02-15

22

Structure, defects, and strain in silicon-silicon oxide interfaces  

SciTech Connect

The structure of the interfaces between silicon and silicon-oxide is responsible for proper functioning of MOSFET devices while defects in the interface can deteriorate this function and lead to their failure. In this paper we modeled this interface and characterized its defects and strain. MD simulations were used for reconstructing interfaces into a thermodynamically stable configuration. In all modeled interfaces, defects were found in the form of three-coordinated silicon atom, five coordinated silicon atom, threefold-coordinated oxygen atom, or displaced oxygen atom. Three-coordinated oxygen atom can be created if dangling bonds on silicon are close enough. The structure and stability of three-coordinated silicon atoms (P{sub b} defect) depend on the charge as well as on the electric field across the interface. The negatively charged P{sub b} defect is the most stable one, but the electric field resulting from the interface reduces that stability. Interfaces with large differences in periodic constants of silicon and silicon oxide can be stabilized by buckling of silicon layer. The mechanical stress resulted from the interface between silicon and silicon oxide is greater in the silicon oxide layer. Ab initio modeling of clusters representing silicon and silicon oxide shows about three time larger susceptibility to strain in silicon oxide than in silicon if exposed to the same deformation.

Kova?evi?, Goran, E-mail: gkova@irb.hr; Pivac, Branko [Department of Materials Physics, Rudjer Boskovic Institute, Bijeni?ka 56, P.O.B. 180, HR-10002 Zagreb (Croatia)

2014-01-28

23

Bismuth Oxide: A New Lithium-Ion Battery Anode  

PubMed Central

Bismuth oxide directly grown on nickel foam (p-Bi2O3/Ni) was prepared by a facile polymer-assisted solution approach and was used directly as a lithium-ion battery anode for the first time. The Bi2O3 particles were covered with thin carbon layers, forming network-like sheets on the surface of the Ni foam. The binder-free p-Bi2O3/Ni shows superior electrochemical properties with a capacity of 668 mAh/g at a current density of 800 mA/g, which is much higher than that of commercial Bi2O3 powder (c-Bi2O3) and Bi2O3 powder prepared by the polymer-assisted solution method (p-Bi2O3). The good performance of p-Bi2O3/Ni can be attributed to higher volumetric utilization efficiency, better connection of active materials to the current collector, and shorter lithium ion diffusion path. PMID:24416506

Li, Yuling; Trujillo, Matthias A.; Fu, Engang; Patterson, Brian; Fei, Ling; Xu, Yun; Deng, Shuguang; Smirnov, Sergei; Luo, Hongmei

2013-01-01

24

Bismuth Oxide: A New Lithium-Ion Battery Anode.  

PubMed

Bismuth oxide directly grown on nickel foam (p-Bi2O3/Ni) was prepared by a facile polymer-assisted solution approach and was used directly as a lithium-ion battery anode for the first time. The Bi2O3 particles were covered with thin carbon layers, forming network-like sheets on the surface of the Ni foam. The binder-free p-Bi2O3/Ni shows superior electrochemical properties with a capacity of 668 mAh/g at a current density of 800 mA/g, which is much higher than that of commercial Bi2O3 powder (c-Bi2O3) and Bi2O3 powder prepared by the polymer-assisted solution method (p-Bi2O3). The good performance of p-Bi2O3/Ni can be attributed to higher volumetric utilization efficiency, better connection of active materials to the current collector, and shorter lithium ion diffusion path. PMID:24416506

Li, Yuling; Trujillo, Matthias A; Fu, Engang; Patterson, Brian; Fei, Ling; Xu, Yun; Deng, Shuguang; Smirnov, Sergei; Luo, Hongmei

2013-10-21

25

Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.  

PubMed

A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell. PMID:25138735

Han, Lihao; Abdi, Fatwa F; van de Krol, Roel; Liu, Rui; Huang, Zhuangqun; Lewerenz, Hans-Joachim; Dam, Bernard; Zeman, Miro; Smets, Arno H M

2014-10-01

26

Higher moments of the implanted-ion profiles of bismuth in silicon  

NASA Astrophysics Data System (ADS)

In this paper, silicon wafers were implanted with bismuth ions ranging from 40 to 360 keV at room temperature. Secondary ion mass spectrometry was used to measure the implanted-ion profiles of bismuth in silicon. The first four moments of the implanted-ion profiles were experimentally determined through least-squares fitting the measured implanted-ion profiles to Pearson distributions. An extension of the Biersack theory up to the fourth order was combined with the Gibbons parabolic fitting formula in making theoretical predictions. A comparison of the measured with calculated values revealed a significant correlation between the calculated and measured values of both the lower (projected range and range straggling) and higher (skewness and kurtosis) moments of the implanted-ion profiles. In addition, the critical energy at which skewness equals zero is defined in this paper. An investigation of ion implantations over the whole range of incident ions reveals that skewness is negative if the incident-ion energy is greater than the critical energy, and vice versa. In addition, the depth profile of lighter ion implantation skews toward the target's surface at lower incident-ion energies than with heavier ion implantation.

Liang, J. H.

1999-06-01

27

A new study on bismuth doped oxide glasses.  

PubMed

Spectroscopic properties of bismuth doped borate, silicate and phosphate glasses have been reinvestigated in this work. It shows the typical decay time of Bi(3+) is around 500ns rather than 2.7-to-3.9 ?s reported by Parke and Webb at room temperature. Introduction of higher content either alkali or alkali earth into borate glasses favors the Bi(3+) emission. As the contents increase excitation peak shifts regularly red while emission peak shows reverse trend. This, as revealed by Huang-Rhys factor, is due to the weakening of coupling between bismuth and glass host, and it can be interpreted within the frame of configurational coordinate diagrams. Differently, as bismuth concentration increases, both the excitation and emission shift red. The unknown origin of red emission from bismuth doped calcium or magnesium phosphate glass has been identified as Bi(2+) species on the basis of excitation spectrum and emission lifetime particularly after comparing with Bi(2+) doped materials. No near infrared (NIR) emission can be detected in these glasses within instrument limit. PMID:22772261

Xu, Wenbin; Peng, Mingying; Ma, Zhijun; Dong, Guoping; Qiu, Jianrong

2012-07-01

28

Incorporation of thiosemicarbazide in Amberlite IRC50 for separation of astatine from ?-irradiated bismuth oxide  

Microsoft Academic Search

A chelating resin was synthesized by incorporating thiosemicarbazide into Amberlite IRC-50, a weakly acidic polymer. Astatine radionuclides produced by ?-irradiating bismuth oxide were separated using the newly synthesized chelating resin. The resin showed high selectivity for astatine. The adsorbed astatine was recovered using 0.1M EDTA at pH?10.

Kamalika Roy; S. Basu; A. Ramaswami; Dalia Nayak; Susanta Lahiri

2004-01-01

29

The effect and mechanism of bismuth doped lead oxide on the performance of lead-acid batteries  

NASA Astrophysics Data System (ADS)

Flooded automotive and motorcycle lead-acid batteries were manufactured from three kinds of lead oxides including electrolyzed pure lead (99.99 wt.% Pb) oxide, electrolyzed pure lead oxide doped with Bi 2O 3 (0.02 wt.% Bi 2O 3) and bismuth-bearing refined lead (0.02 wt.% Bi) oxide. The first cranking and cold cranking curves of the automotive batteries show that there is no obvious difference among the above lead oxides. Bismuth in lead oxide does not affect the water loss of flooded batteries. However, bismuth results in the improvement of capacity and charge-acceptance capability. In discharge, the positive voltage versus cadmium of plates with bismuth decreases more slowly than that of plates without bismuth. In order to investigate the mechanism of the function of bismuth, three other kinds of test electrodes were prepared from electrolyzed pure lead (99.99 wt.% Pb) oxide, electrolyzed pure lead oxide doped 0.02 wt.% Bi 2O 3 and electrolyzed pure lead oxide doped 0.06 wt.% Bi 2O 3. The cyclic voltammetry curve shows that bismuth has no significant influence on the electrochemical behavior of the positive active-material. There is an opposite result concerning the cathodic polarization curves between bismuth doped in the electrode and Bi 3+ ion doped in the electrolyte. Bismuth doped in the electrode results in a decrease of the hydrogen overpotential. Conversely, Bi 3+ ion doped in the electrolyte results is an increase. The chemical analysis confirms that a trace of Bi 3+ ion exists in sulfuric acid solution (e.g. plates soaking, after formation, after cycling). A higher porosity is observed in the positive active-material containing bismuth by SEM technique. SEM morphology shows that needle-like crystals begin to occur after a few cycles. X-ray diffraction phase analysis proves that the amount of ?-PbO 2 is increased by doping bismuth in to lead oxide. The existing forms, chemical characteristics and electrochemical reactions of bismuth during manufacture and are of lead-acid batteries are demonstrated clearly. The mechanism of the function of bismuth improving capacity, prolonging cycle-life and reducing water loss has been elucidated in detail.

Chen, H. Y.; Wu, L.; Ren, C.; Luo, Q. Z.; Xie, Z. H.; Jiang, X.; Zhu, S. P.; Xia, Y. K.; Luo, Y. R.

30

Analysis of quantum coherence in bismuth-doped silicon: a system of strongly coupled spin qubits  

E-print Network

There is growing interest in bismuth-doped silicon (Si:Bi) as an alternative to the well-studied proposals for silicon based quantum information processing (QIP) using phosphorus-doped silicon (Si:P). We focus here on the implications of its anomalously strong hyperfine coupling. In particular, we analyse in detail the regime where recent pulsed magnetic resonance experiments have demonstrated the potential for orders of magnitude speedup in quantum gates by exploiting transitions that are electron paramagnetic resonance (EPR) forbidden at high fields. We also present calculations using a phenomenological Markovian master equation which models the decoherence of the electron spin due to Gaussian temporal magnetic field perturbations. The model quantifies the advantages of certain "optimal working points" identified as the $df/dB=0$ regions, where $f$ is the transition frequency, which come in the form of frequency minima and maxima. We show that at such regions, dephasing due to the interaction of the electron spin with a fluctuating magnetic field in the $z$ direction (usually adiabatic) is completely removed.

M. H. Mohammady; G. W. Morley; A. Nazir; T. S. Monteiro

2012-07-04

31

Promotional Effects of Bismuth on the Formation of Platinum-Bismuth Nanowires Network and the Electrocatalytic Activity toward Ethanol Oxidation  

SciTech Connect

Electrocatalytic activities of Pt and their alloys toward small organic molecules oxidation are highly dependent on their morphology, chemical composition, and electronic structure. Here, we report the synthesis of dendrite-like Pt{sub 95}Bi{sub 5}, Pt{sub 83}Bi{sub 17}, and Pt{sub 76}Bi{sub 24} nanowires network with a high aspect ratio (up to 68). The electronic structure and heterogeneous crystalline structure have been studied using combined techniques, including aberration-corrected scanning transmission electron microscopy (STEM) and X-ray absorption near-edge structure (XANES) spectroscopy. Bismuth-oriented attachment growth mechanism has been proposed for the anisotropic growth of Pt/Bi. The electrochemical activities of Pt/Bi nanowires network toward ethanol oxidations have been tested. In particular, the as-made Pt{sub 95}Bi{sub 5} appears to have superior activity toward ethanol oxidation in comparison with the commercial Pt/C catalyst. The reported promotional effect of Bi on the formation of Pt/Bi and electrochemical activities will be important to design effective catalysts for ethanol fuel cell application.

X Teng; W Du; D Su; Q Wang; A Frenkel

2011-12-31

32

Method of forming buried oxide layers in silicon  

DOEpatents

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir City, TN)

2000-01-01

33

Retention Reliability Improvement of Silicon-Oxide-Nitride-Oxide-Silicon Nonvolatile Memory with N2O Oxidation Tunnel Oxide  

Microsoft Academic Search

The reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) devices with different thin tunnel oxides are studied. The device with the tunnel oxynitride grown in pure N2O ambient at a high temperature has better performance, including better leakage current, programming speed, read-disturb, and retention characteristics, than that with a tunnel oxide layer grown by dry oxidation with N2 annealing treatment. Moreover, the properties

Jia-Lin Wu; Chin-Hsing Kao; Hua-Ching Chien; Tzung-Kuen Tsai; Chien-Wei Liao

2007-01-01

34

Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode  

NASA Astrophysics Data System (ADS)

Metal oxides are generally very stable in aqueous solutions and cheap, but their photochemical activity is usually limited by poor charge carrier separation. Here we show that this problem can be solved by introducing a gradient dopant concentration in the metal oxide film, thereby creating a distributed n+-n homojunction. This concept is demonstrated with a low-cost, spray-deposited and non-porous tungsten-doped bismuth vanadate photoanode in which carrier-separation efficiencies of up to 80% are achieved. By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3?mA?cm-2, respectively, are achieved under 1 sun illumination. The 4?mA?cm-2 photocurrent corresponds to a solar-to-hydrogen efficiency of 4.9%, which is the highest efficiency yet reported for a stand-alone water-splitting device based on a metal oxide photoanode.

Abdi, Fatwa F.; Han, Lihao; Smets, Arno H. M.; Zeman, Miro; Dam, Bernard; van de Krol, Roel

2013-07-01

35

Efficient solar water splitting by enhanced charge separation in a bismuth vanadate-silicon tandem photoelectrode.  

PubMed

Metal oxides are generally very stable in aqueous solutions and cheap, but their photochemical activity is usually limited by poor charge carrier separation. Here we show that this problem can be solved by introducing a gradient dopant concentration in the metal oxide film, thereby creating a distributed n(+)-n homojunction. This concept is demonstrated with a low-cost, spray-deposited and non-porous tungsten-doped bismuth vanadate photoanode in which carrier-separation efficiencies of up to 80% are achieved. By combining this state-of-the-art photoanode with an earth-abundant cobalt phosphate water-oxidation catalyst and a double- or single-junction amorphous Si solar cell in a tandem configuration, stable short-circuit water-splitting photocurrents of ~4 and 3 mA cm(-2), respectively, are achieved under 1 sun illumination. The 4 mA cm(-2) photocurrent corresponds to a solar-to-hydrogen efficiency of 4.9%, which is the highest efficiency yet reported for a stand-alone water-splitting device based on a metal oxide photoanode. PMID:23893238

Abdi, Fatwa F; Han, Lihao; Smets, Arno H M; Zeman, Miro; Dam, Bernard; van de Krol, Roel

2013-01-01

36

Pharmacokinetics of metronidazole, tetracycline and bismuth in healthy volunteers after oral administration of compound tablets containing a combination of metronidazole, tetracycline hydrochloride and bismuth oxide.  

PubMed

To eradicate Helicobacter pylori in human pylorus and to heal duodenal ulcers, recently, a new formulation of combination tablets containing metronidazole 125?mg, tetracycline hydrochloride 125?mg and bismuth oxide 40?mg has been developed.To investigate the pharmacokinetics of metronidazole, tetracycline and bismuth in healthy Chinese volunteers after oral administration of the test formulation.A one-sequence, 3-period study was conducted in 12 Chinese healthy volunteers (6 male, 6 female). Volunteers each received single low dose (1 tablet) under fed condition in period 1, single high dose (3 tablets) under fasted condition in period 2, and single high dose (3 tablets) and multiple doses (3 tablets at once, 4 times daily for 7 consecutive days) under fed condition in period 3. Blood samples were collected and determined over 48?h in every period.After single high dose administration under fed condition, the C max of metronidazole, tetracycline and bismuth were 6.833±0.742??g/mL, 0.8513±0.1253??g/mL and 3.32±1.89?ng/mL, respectively. The C max and AUC 0-48 of metronidazole increased in proportion to the doses within the tested dose range, but tetracycline and bismuth did not. Food caused 10% and 80% decrease of the C max for metronidazole and bismuth, respectively, but did not affect tetracycline. No gender effect was found on the pharmacokinetics of the 3 ingredients. In the steady state, the C av of metronidazole, tetracycline and bismuth were 20.75±3.52??g/mL, 1.900±0.243??g/mL and 5.61±1.34?ng/mL, respectively. PMID:24764254

Wu, Y; Ding, L; Huang, N-Y; Wen, A-D; Liu, B; Li, W-B

2015-02-01

37

Understanding of the Retarded Oxidation Effects in Silicon Nanostructures  

E-print Network

Understanding of the Retarded Oxidation Effects in Silicon Nanostructures C. Krzeminski and X the oxidation of silicon nanostructures is proposed. The wet thermal oxidation of various silicon nanostructures in silicon nanostructures. With the current top-down fabrication capabilities, etched silicon nanostructures

Boyer, Edmond

38

Quantitative measurement of the surface silicon interstitial boundary condition and silicon interstitial injection into silicon during oxidation  

E-print Network

Quantitative measurement of the surface silicon interstitial boundary condition and silicon interstitial injection into silicon during oxidation M. S. Carroll* and J. C. Sturm Department of Electrical the oxidation of silicon, interstitials are generated at the oxidizing surface and diffuse into the silicon

39

Capacity and cycle-life of batteries using bismuth-bearing oxide  

NASA Astrophysics Data System (ADS)

An examination is made of the capacity performance of lead-acid positive electrodes which are prepared from bismuth (Bi)-bearing oxide. This oxide is produced from Pasminco VRLA Refined™ lead which contains 0.05 wt.% Bi. For comparison, benchmark tests are performed on electrodes made from oxide with virtually no bismuth (<0.005 wt.%). The change in capacity is investigated by means of a purpose-built `compression cell'. With this design, the positive active-material is constrained under the action of a desirable, constant force during charge-discharge cycling. In general, the capacity increases with the compressive force. Importantly, the use of Bi-bearing oxide yields higher initial capacity and then a significantly faster rise in capacity to the full value with subsequent cycling. Commercial VRLA batteries made with Bi-bearing oxide exhibit a lower rate of self-discharge than those fabricated with conventional factory oxide. In addition, Bi-bearing batteries provide good cycle-life under the International Electrotechnical Commission (IEC) test.

Lam, L. T.; Haigh, N. P.; Lim, O. V.; Rand, D. A. J.; Manders, J. E.

40

Mullite interaction with bismuth oxide from minerals and sol-gel processes  

E-print Network

The high temperature treatment of kaolinite-muscovite alternate layers doped by bismuth oxide was studied by TGA and DTA, X ray diffraction, and electron microscopy (SEM). Thermal analyses shows that the two main transformation stages are the dehydroxylation of phyllosilicates and the structural reorganization of the whole assembly. During dehydroxylation, a progressive decrease of the structural order of kaolinite and muscovite occurs. It is more significant at temperature above 1000°C and mullite, glass and Alrich oxides are formed. Mullite exhibits an accentuated acicular morphology along 3 preferential orientations in relation to the remaining structure in the basal (001)musc planes of the former muscovite. With addition of

F. Gridi-bennadji; J. Zimová; J. P. Laval; P. Blanchart

2008-01-01

41

Bismuth- and aluminum-codoped germanium oxide glasses for super-broadband optical amplification  

NASA Astrophysics Data System (ADS)

Broadband infrared luminescence from bismuth-doped germanium oxide glasses prepared by a conventional melting-quenching technique was discovered. The absorption spectrum of the glasses covered a wide range from the visible to the near-infrared wavelength regions and consisted of five broad peaks below 370, 500, 700, 800, and 1000 nm. The fluorescence spectrum exhibited broadband characteristics (FWHM) greater than 300 nm with a maximum at 1300 nm pumped by an 808-nm laser. The fluorescence lifetime at room temperature decreased with increasing Bi2O3 concentration in the glass. Codoping of aluminum and bismuth was indispensable for the broadband infrared luminescence in GeO2:Bi, Al glass.

Peng, Mingying; Qiu, Jianrong; Chen, Danping; Meng, Xiangeng; Yang, Ivyun; Jiang, Xiongwei; Zhu, Congshan

2004-09-01

42

Bismuth- and aluminum-codoped germanium oxide glasses for super-broadband optical amplification.  

PubMed

Broadband infrared luminescence from bismuth-doped germanium oxide glasses prepared by a conventional melting-quenching technique was discovered. The absorption spectrum of the glasses covered a wide range from the visible to the near-infrared wavelength regions and consisted of five broad peaks below 370, 500, 700, 800, and 1000 nm. The fluorescence spectrum exhibited broadband characteristics (FWHM) greater than 300 nm with a maximum at 1300 nm pumped by an 808-nm laser. The fluorescence lifetime at room temperature decreased with increasing Bi2O3 concentration in the glass. Codoping of aluminum and bismuth was indispensable for the broadband infrared luminescence in GeO2:Bi, Al glass. PMID:15455759

Peng, Mingying; Qiu, Jianrong; Chen, Danping; Meng, Xiangeng; Yang, Ivyun; Jiang, Xiongwei; Zhu, Congshan

2004-09-01

43

Silicon oxide colloidal/polymer nanocomposite films Haifeng Wanga)  

E-print Network

Silicon oxide colloidal/polymer nanocomposite films Haifeng Wanga) and Wenwu Cao Materials Research to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite

Cao, Wenwu

44

Heat-reflecting windows using gold and bismuth oxide films  

Microsoft Academic Search

Thin gold films sandwiched between certain metal oxide layers possess a high electrical conductivity and high optical transparency. They also have a high infra-red reflectance, and may be used as transparent heat-reflecting coatings if their yellowish tinted colour in transmitted light can be tolerated. The observation window of an enclosure exposed to infra-red radiation was coated with different film combinations,

L. Holland; G. Siddall

1958-01-01

45

Understanding of the Retarded Oxidation Effects in Silicon Nanostructures  

E-print Network

Understanding of the Retarded Oxidation Effects in Silicon Nanostructures C. Krzeminski,, X.-L. Han-limited oxidation phenomenon observed during the oxidation of silicon nanostructures is proposed. The wet thermal oxidation of various silicon nanostructures such as nanobeams, concave/convex nanorings and nanowires

46

Bismuth doped lanthanum ferrite perovskites as novel cathodes for intermediate-temperature solid oxide fuel cells.  

PubMed

Bismuth is doped to lanthanum strontium ferrite to produce ferrite-based perovskites with a composition of La(0.8-x)Bi(x)Sr0.2FeO(3-?) (0 ? x ? 0.8) as novel cathode material for intermediate-temperature solid oxide fuel cells. The perovskite properties including oxygen nonstoichiometry coefficient (?), average valence of Fe, sinterability, thermal expansion coefficient, electrical conductivity (?), oxygen chemical surface exchange coefficient (K(chem)), and chemical diffusion coefficient (D(chem)) are explored as a function of bismuth content. While ? decreases with x due to the reduced Fe(4+) content, D(chem) and K(chem) increase since the oxygen vacancy concentration is increased by Bi doping. Consequently, the electrochemical performance is substantially improved and the interfacial polarization resistance is reduced from 1.0 to 0.10 ? cm(2) at 700 °C with Bi doping. The perovskite with x = 0.4 is suggested as the most promising composition as solid oxide fuel cell cathode material since it has demonstrated high electrical conductivity and low interfacial polarization resistance. PMID:24971668

Li, Mei; Wang, Yao; Wang, Yunlong; Chen, Fanglin; Xia, Changrong

2014-07-23

47

Thermodynamic stability of binary oxides in contact With silicon  

Microsoft Academic Search

Using tabulated thermodynamic data, a comprehensive investigation of the thermodynamic stability of binary oxides in contact with silicon at 1000 K was conducted. Reactions between silicon and each binary oxide at 1000 K, including those involving ternary phases, were considered. Sufficient data exists to conclude that all binary oxides except the following are thermodynamically unstable in contact with silicon at

K. J. Hubbard; D. G. Schlom

1996-01-01

48

Electrical reliability of silicon oxynitride prepared by thermal oxidation of LPCVD silicon-rich silicon nitride.  

E-print Network

??To further aggressively downscale the metal-oxide-semiconductor (MOS) devices, silicon oxynitride will be one of the most promising and technologically feasible dielectric materials to replace conventional… (more)

Choi, Hok Yin (???)

2007-01-01

49

Diffusion of Indium Implanted in Silicon Oxides  

NASA Astrophysics Data System (ADS)

Indium atoms were implanted into silicon oxides to study indium diffusion during annealing and deposition processes. In the thermal oxide, the peak indium concentration decays without marked profile broadening, suggesting that a large fraction of indium is immobile during annealing in nitrogen. Oxygen ambient was found to reduce the decay of the indium peak in thermal oxide. The tail diffusion of indium was observed in thermal oxide after chemical vapor deposition using tetraethoxysilane (TEOS) or SiH4 as the precursor. The tail diffusion increases as TEOS oxide replaces thermal oxide. However, performing densification annealing before indium implantation reduces the tail diffusion in TEOS oxide. The tail diffusion indicates an increase in the concentration of mobile indium atoms. Experimental results suggest that hydrogen from deposition processes is important in indium tail diffusion.

Chang, Ruey-Dar; Ling, Yu-Ting; Liu, Taylor; Tsai, Jung-Ruey; Ma, Chia-Chi

2009-05-01

50

Fabrication of planar silicon nanowires on silicon-on-insulator using stress limited oxidation  

E-print Network

Fabrication of planar silicon nanowires on silicon-on-insulator using stress limited oxidation for the fabrication of planar single crystal silicon nanowires down to 8 nm in diameter. In this method silicon lines are defined on silicon-on-insulator with electron beam lithography followed by a metal liftoff process

Bokor, Jeffrey

51

Retention Reliability Improvement of Silicon-Oxide-Nitride-Oxide-Silicon Nonvolatile Memory with N2O Oxidation Tunnel Oxide  

NASA Astrophysics Data System (ADS)

The reliability characteristics of silicon-oxide-nitride-oxide-silicon (SONOS) devices with different thin tunnel oxides are studied. The device with the tunnel oxynitride grown in pure N2O ambient at a high temperature has better performance, including better leakage current, programming speed, read-disturb, and retention characteristics, than that with a tunnel oxide layer grown by dry oxidation with N2 annealing treatment. Moreover, the properties of two-bit operation are also displayed by a reverse read method. Furthermore, the surface roughness and interface states between a tunnel oxide layer and a Si substrate are also observed by atomic force microscopy (AFM) and charge-pumping method to evaluate interfacial nitrogen incorporation. The results show that data retention reliability attained a significant improvement while maintaining good programming/erase performance and two-bit operation. This work can provide a straightforward way of reliability improvement for future flash memory application.

Wu, Jia-Lin; Kao, Chin-Hsing; Chien, Hua-Ching; Tsai, Tzung-Kuen; Liao, Chien-Wei

2007-10-01

52

Silicon oxide colloidal/polymer nanocomposite films  

NASA Astrophysics Data System (ADS)

The quarter-wavelength (?/4) acoustic matching layer, a vital component in medical ultrasonic transducer, can bridge the large acoustic impedance mismatch between the piezoelectric material and the human body. Composite materials are widely used as matching materials in order to cover the wide acoustic impedance range that cannot be accomplished by using a single-phase material. At high frequencies (>50MHz), the ? /4 matching layers become extremely thin so that the fabrication of homogeneous composite material matching layers becomes very challenging. A method is reported in this letter to fabricate sol-gel silicon oxide colloidal/polymer composite film on silicon substrate, in which the particle size of silicon oxide colloidal is between 10 and 40 nm. The acoustic impedance of the nanocomposite films versus aging temperature has been measured at the desired operating frequency.

Wang, Haifeng; Cao, Wenwu; Zhou, Q. F.; Shung, K. Kirk; Huang, Y. H.

2004-12-01

53

Metal-oxide-silicon diodes on deuterium-implanted silicon substrate and R. K. Jarwal  

E-print Network

PROOF COPY 047021APL Metal-oxide-silicon diodes on deuterium-implanted silicon substrate D. Misraa implantation was used to incorporate deuterium at the Si­SiO2 interface. Polycrystalline silicon gate metal-oxide0003-6951 00 04721-5 Role of hydrogen in metal-oxide-semiconductor MOS device stability and reliability

Misra, Durgamadhab "Durga"

54

Boron Undoped and Doped Europium-Bismuth Oxide Nanocomposites via the Polymeric Precursor Technique  

NASA Astrophysics Data System (ADS)

Boron-undoped and -doped europium-bismuth oxide nanocomposites were synthesized by the polymeric precursor technique. The solutions were calcined and sintered to prepare nanocomposite powders. The nanocomposites were characterized by the Fourier transform infrared spectroscopy, x-ray diffraction, scanning electron microscope, and Brauner-Emmett-Teller techniques. According to Fourier transform infrared spectroscopy results, the shape, the range, and the intensity of the peaks for the calcined and sintered samples changed with the addition of boron content. Furthermore, the reaction path, resulting crystal size, and crystal morphology were all altered by boron additions. A decrease in porosity, brought about by boron additions, also altered the N2 absorption/desorption characteristics.

Aytimur, Arda; Koçyi?it, Serhat; Temel, Sinan; Uslu, Ibrahim

2014-08-01

55

Some preliminary observations of the rapid thermal oxidation of porous silicon, and the rapid thermal nitriding of oxidized porous silicon  

SciTech Connect

Porous silicon, produced by the anodic oxidation of [ital p]-type single crystal wafers of silicon in hydrofluoric acid/ethanol electrolytes has been subjected to rapid thermal oxidation. For comparison purposes, and also to generate porous oxide for subsequent nitriding, other samples of porous silicon were subjected to conventional furnace oxidation. By TEM, EDS, and ESCA it was shown that the structures and compositions of the oxides produced by the two routes were similar. It was further demonstrated that oxidized porous silicon could be nitrided by rapid thermal processing. The resulting structure, although still porous, showed a much diminished etching rate in hydrofluoric acid, compared to the original oxide.

Shieh, S.; Evans, J.W. (Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States) Materials Science Divison, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

1994-05-01

56

Visible light photooxidative performance of a high-nuclearity molecular bismuth vanadium oxide cluster  

PubMed Central

Summary The visible light photooxidative performance of a new high-nuclearity molecular bismuth vanadium oxide cluster, H3[{Bi(dmso)3}4V13O40], is reported. Photocatalytic activity studies show faster reaction kinetics under anaerobic conditions, suggesting an oxygen-dependent quenching of the photoexcited cluster species. Further mechanistic analysis shows that the reaction proceeds via the intermediate formation of hydroxyl radicals which act as oxidant. Trapping experiments using ethanol as a hydroxyl radical scavenger show significantly decreased photocatalytic substrate oxidation in the presence of EtOH. Photocatalytic performance analyses using monochromatic visible light irradiation show that the quantum efficiency ? for indigo photooxidation is strongly dependent on the irradiation wavelength, with higher quantum efficiencies being observed at shorter wavelengths (?395nm ca. 15%). Recycling tests show that the compound can be employed as homogeneous photooxidation catalyst multiple times without loss of catalytic activity. High turnover numbers (TON ca. 1200) and turnover frequencies up to TOF ca. 3.44 min?1 are observed, illustrating the practical applicability of the cluster species. PMID:24991508

Tucher, Johannes

2014-01-01

57

Method of making silicon carbide-silicon composite having improved oxidation resistance  

NASA Technical Reports Server (NTRS)

A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

Luthra, Krishan Lal (Inventor); Wang, Hongyu (Inventor)

2002-01-01

58

Silicon carbide-silicon composite having improved oxidation resistance and method of making  

NASA Technical Reports Server (NTRS)

A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

Luthra, Krishan Lal (Inventor); Wang, Hongyu (Inventor)

1999-01-01

59

Characteristics of rational harmonic mode?locked short?cavity fiber ring laser using a bismuth?oxide-based erbium?doped fiber and a bismuth?oxide?based highly nonlinear fiber.  

PubMed

We demonstrate a rational harmonic mode-locked fiber ring laser employing a 151-cm-long bismuth-oxide-based erbium-doped fiber (Bi-EDF) and a 250-cm-long bismuth-oxide-based highly nonlinear fiber (Bi-HNLF). Continuous wavelength tuning covering both the conventional wavelength band and the longer wavelength band can be achieved by utilizing the wide gain bandwidth of the Bi-EDF. The pulse amplitude can also be equalized by adjusting the modulation parameters of the intracavity modulator. Ultra-high nonlinearity of the Bi-HNLF collaborates with spectral filtering by an optical bandpass filter to suppress the supermode noise quite effectively. The total cavity length is as short as 10 m. Stable and amplitude equalized pulses up to 40 GHz can be successfully generated over the entire wavelength tuning range. PMID:22109128

Fukuchi, Yutaka; Maeda, Joji

2011-11-01

60

Silicon atoms in ECR oxide deposition plasmas  

NASA Astrophysics Data System (ADS)

Silicon atom concentrations were measured in silane/oxygen and tetraethoxysilane (TEOS)/oxygen plasmas created in a 2.45 GHz electron cyclotron resonance (ECR) reactor. Atomic absorption using a Si hollow-cathode lamp source was applied to measure attenuation of the six Si I resonance lines 4s ^3P^0 - 3p^2 ^3P (250.69 - 252.85 nm) permitting independent determination of the populations of the three sublevels (J = 0, 1, 2) of the ground state. The relative populations followed a Boltzmann distribution, and the determined internal temperature varied from 380 K (200 W) to 720 K (650 W). Silicon atom concentration increased with power and silane or TEOS flow rate, reaching 10^11 cm-3 at 650 W, 5 mTorr, 20 sccm of SiH_4, and 20 sccm of O_2. The Si concentration was strongly correlated with the deposition rate and quality of the silicon oxide films. Inferred Si atom fluxes were high enough to account for the observed silicon oxide deposition rates in silane/oxygen plasmas. This work was supported by the NSF under Grant No.EEC-8721545.

Augustyniak, Edward; Chew, Kok Heng; Shohet, J. Leon; Woods, R. Claude

1996-10-01

61

Development of tellurium oxide and lead-bismuth oxide glasses for mid-wave infra-red transmission optics  

NASA Astrophysics Data System (ADS)

Heavy metal oxide glasses exhibiting high transmission in the Mid-Wave Infra-Red (MWIR) spectrum are often difficult to manufacture in large sizes with optimized physical and optical properties. In this work, we researched and developed improved tellurium-zinc-barium and lead-bismuth-gallium heavy metal oxide glasses for use in the manufacture of fiber optics, optical components and laser gain materials. Two glass families were investigated, one based upon tellurium and another based on lead-bismuth. Glass compositions were optimized for stability and high transmission in the MWIR. Targeted glass specifications included low hydroxyl concentration, extended MWIR transmission window, and high resistance against devitrification upon heating. Work included the processing of high purity raw materials, melting under controlled dry Redox balanced atmosphere, finning, casting and annealing. Batch melts as large as 4 kilograms were sprue cast into aluminum and stainless steel molds or temperature controlled bronze tube with mechanical bait. Small (100g) test melts were typically processed in-situ in a 5%Au°/95%Pt° crucible. Our group manufactured and evaluated over 100 different experimental heavy metal glass compositions during a two year period. A wide range of glass melting, fining, casting techniques and experimental protocols were employed. MWIR glass applications include remote sensing, directional infrared counter measures, detection of explosives and chemical warfare agents, laser detection tracking and ranging, range gated imaging and spectroscopy. Enhanced long range mid-infrared sensor performance is optimized when operating in the atmospheric windows from ~ 2.0 to 2.4?m, ~ 3.5 to 4.3?m and ~ 4.5 to 5.0?m.

Zhou, Beiming; Rapp, Charles F.; Driver, John K.; Myers, Michael J.; Myers, John D.; Goldstein, Jonathan; Utano, Rich; Gupta, Shantanu

2013-03-01

62

Effect of silicon oxide, silicon nitride and polysilicon layers on the electrostatic pressure during anodic bonding  

Microsoft Academic Search

The quality of the anodic bonding between glass and silicon wafers coated with silicon oxide, silicon nitride and polysilicon layers has been investigated. We have used an electrostatic test to study the effect of these layers on the quality of the bond. The electrostatic test shows how the electrostatic pressure decreases with the increase of the thickness of the silicon

J. A. Plaza; J. Esteve; E. Lora-Tamayo

1998-01-01

63

Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement  

PubMed Central

Objectives To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p<0.05). Results The results showed an increase of the pH level after 15 days, followed by a slight increase after 30 days and a decrease after 60 days. There were no significant statistical differences among the groups (p>0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05). Conclusions The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated. PMID:25141197

MARCIANO, Marina Angélica; GARCIA, Roberto Brandão; CAVENAGO, Bruno Cavalini; MINOTTI, Paloma Gagliardi; MIDENA, Raquel Zanin; GUIMARÃES, Bruno Martini; ORDINOLA-ZAPATA, Ronald; DUARTE, Marco Antonio Hungaro

2014-01-01

64

Suppression of decoherence due to spin diffusion for bismuth qubits in silicon  

E-print Network

We present pulsed electron-nuclear double resonance experiments which enable us to quantify and characterize, for the first time, the coupling between bismuth donor spin qubits and the surrounding $^{29}\\text{Si}$ impurities; the latter provide the dominant decoherence mechanism (nuclear spin diffusion) in this system. Cluster expansion simulations show near-complete suppression of spin diffusion at optimal working points. The suppression takes the form of sharply peaked divergences of the spin diffusion time $T_{\\text{SD}}$, in contrast with previously identified broader regions of insensitivity to classical fluctuations.

Balian, S J; Mohammady, M H; Morley, G W; Witzel, W M; Kay, C W M; Monteiro, T S

2012-01-01

65

Lateral epitaxial growth of germanium on silicon oxide  

SciTech Connect

We have developed a method using local oxidation on silicon to create nanoscale silicon seeds for the lateral epitaxial overgrowth of germanium on silicon oxide. The germanium growth starts selectively from silicon seed lines, proceeds by wetting the SiO{sub 2} layer and coalesces without formation of grain boundary. Analysis by high resolution transmission electron microscopy have shown that Ge layers grown above silicon oxide are perfectly monocrystalline and are free of defect. The only detected defects are situated at the Ge/Si interface. Geometrical phase analyses of the microscopy images have shown that the Ge layer is fully relaxed and homogeneous.

Cammilleri, V. D.; Yam, V.; Fossard, F.; Renard, C.; Bouchier, D. [Institut d'Electronique Fondamentale, CNRS UMR 8622, Universite Paris-Sud, Bat 220, 91405 Orsay (France); Fazzini, P. F.; Houdellier, F.; Hyetch, M. [CEMES-CNRS, University of Toulouse, 29, Rue Jeanne Marvig, 31055, Toulouse Cedex 4 (France); Ortolani, L. [CEMES-CNRS, University of Toulouse, 29, Rue Jeanne Marvig, 31055, Toulouse Cedex 4 (France); University of Bologna, Department of Physics, v.le B. Pichat, 6/2, 40127 Bologna (Italy) and CNR-IMM Bologna, v. Gobetti, 101, 40129 Bologna (Italy)

2008-07-28

66

Correlation between matrix structural order and compressive stress exerted on silicon nanocrystals embedded in silicon-rich silicon oxide  

PubMed Central

Abstract Silicon nanocrystals embedded in a silicon oxide matrix were deposited by radio frequency reactive magnetron sputtering. By means of Raman spectroscopy, we have found that a compressive stress is exerted on the silicon nanocrystal cores. The stress varies as a function of silicon concentration in the silicon-rich silicon oxide layers varies, which can be attributed to changes of nanocrystal environment. By conducting the Fourier transform infrared absorption experiments, we have correlated the stresses exerted on the nanocrystal core to the degree of matrix structural order. PACS 78.67.Bf, 78.67.Pt, 73.63.Bd, 78.47.D, 74.25.Nd PMID:23336352

2013-01-01

67

Easy synthesis of bismuth iron oxide nanoparticles as photocatalyst for solar hydrogen generation from water  

NASA Astrophysics Data System (ADS)

In this study, high purity bismuth iron oxide (BiFeO3/BFO) nanoparticles of size 50-80 nm have been successfully synthesized by a simple sol-gel method using urea and polyvinyl alcohol at low temperature. X-ray diffraction (XRD) measurement is used to optimize the synthetic process to get highly crystalline and pure phase material. Diffuse reflectance ultraviolet-visible (DRUV-Vis) spectrum indicates that the absorption cut-off wavelength of the nanoparticles is about 620 nm, corresponding to an energy band gap of 2.1 eV. Compared to BaTiO3, BFO has a better degradation of methyl orange under light radiation. Also, photocatalytic tests prove this material to be efficient towards water splitting under simulated solar light to generate hydrogen. The simple synthetic methodology adopted in this paper will be useful in developing low-cost semiconductor materials as effective photocatalysts for hydrogen generation. Photocatalytic tests followed by gas chromatography (GC) analyses show that BiFeO3 generates three times more hydrogen than commercial titania P25 catalyst under the same experimental conditions.

Deng, Jinyi

68

Photoelectrochemical processes in bismuth germanium oxide, Bi12GeO20 single crystals  

NASA Astrophysics Data System (ADS)

The photoelectrochemical properties of bismuth germanium oxide (BGO) single crystals are studied. The crystals were grown by the Czochralski method from a Bi2O3 and GeO2 melt, and semiconductor samples were cut perpendicular to the growth axis, and subsequently polished, treated in concentrated HCl and then reduced in a hydrogen atmosphere at 500-600 C for 1 hr. The semiconductor electrode was illuminated with an illumination intensity of about 200 mW/sq cm, and electrochemical measurements were made in a two compartment cell containing a 5 N NaOh electrolyte and with a saturated calomel electrode as the referencyelectrode. It is observed from the obtained I-V curve that the reduced BGO wafers have n-type semiconductor properties, while the unreduced samples have neglibible anodic and cathodic currents and exhibited no photosensitivity. Photosensitivity up to 0.5 micron in the range of 400-500 nm was observed and a flatband potential of about -0.68 V vs. SCE was determined. It is assumed that oxygen vacancies were created during the reduction process, and the fact that a thermal treatment for a short time in an oxygen atmosphere restores the original electrical and optical properties of the semiconductor supports this assumption. The flatband potential of -0.68 V suggests that photoelectrolysis cannot be possible without an external energy source, but it is noted that the use of this semiconductor with an appropriate redox system in self-generating solar cells is possible.

Kochev, K.; Tsvetkova, K.; Gospodinov, M.

1983-02-01

69

Piezoelectric properties of high Curie temperature barium titanate-bismuth perovskite-type oxide system ceramics  

NASA Astrophysics Data System (ADS)

Barium titanate (BaTiO3, BT)—bismuth magnesium titanium oxide [Bi(Mg0.5Ti0.5)O3, BMT] system ceramics were prepared in an ambient atmosphere in order to increase the Curie temperature (Tc) of BT above 132 °C. A single perovskite phase was observed for BT-BMT ceramics with BMT compositions less than 50 mol %, and their relative densities were greater than 94%. Synchrotron measured x-ray diffraction patterns revealed that all the cations in the ceramics were homogeneously distributed. The temperature dependence of the dielectric properties revealed that the BT-BMT system ceramics exhibited relaxorlike characteristics with a dielectric maximum temperature as high as 360 °C for the 0.5BT-0.5BMT ceramic. The apparent piezoelectric constant (d?) was 60 pC/N for the 0.4BT-0.6BMT ceramic. Based upon these results, the BT-BMT system shows potential as a new type of lead-free material for high Tc piezoelectric applications.

Wada, Satoshi; Yamato, Keisuke; Pulpan, Petr; Kumada, Nobuhiro; Lee, Bong-Yeon; Iijima, Takashi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

2010-11-01

70

The Active Oxidation of Silicon Carbide  

NASA Technical Reports Server (NTRS)

The high temperature oxidation of silicon carbide occurs in two very different modes. Passive oxidation forms a protective oxide film which limits further attack of the SiC: SiC(s) + 3/2 O2(g) = SiO2(s) + CO(g) Active oxidation forms a volatile oxide and may lead to extensive attack of the SiC: SiC(s) + O2(g) = SiO(g) + CO(g) Generally passive oxidation occurs at higher oxidant pressures and active oxidation occurs at lower oxidant pressures and elevated temperatures. Active oxidation is a concern for reentry, where the flight trajectory involves the latter conditions. Thus the transition points and rates of active oxidation are a major concern. Passive/active transitions have been studied by a number of investigators. An examination of the literature indicates many questions remain regarding the effect of impurity, the hysteresis of the transition (i.e. the difference between active-to-passive and passive-toactive), and the effect of total pressure. In this study we systematically investigate each of these effects. Experiments were done in both an alumina furnace tube and a quartz furnace tube. It is known that alumina tubes release impurities such as sodium and increase the kinetics in the passive region [1]. We have observed that the active-to-passive transition occurs at a lower oxygen pressure when the experiment is conducted in alumina tubes and the resultant passive silica scale contains sodium. Thus the tests in this study are conducted in quartz tubes. The hysteresis of the transition has been discussed in the detail in the original theoretical treatise of this problem for pure silicon by Wagner [2], yet there is little mention of it in subsequent literature. Essentially Wagner points out that the active-to-passive transition is governed by the criterion for a stable Si/SiO2 equilibria and the passive-to-active transition is governed by the decomposition of the SiO2 film. A series of experiments were conducted for active-to-passive and passive-to-active transitions by increasing and decreasing oxygen pressure, respectively. For pure silicon a dramatic difference was found; whereas for SiC the difference was not as great. This may be due to the oxidation of the carbon in SiC which may break down the scale [3]. The third area is the effect of total pressure. In the literature, low oxygen potentials are achieved via either low total pressure or low oxygen pressure in an O2/Ar mixture. Both types of experiments are done in this study and the differences are discussed with regard to the presence or absence of a boundary layer.

Jacobson, Nathan S.; Myers, Dwight L.

2009-01-01

71

Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation  

E-print Network

Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation been suggested that gamma irradiation accelerates oxidation of porous silicon.5 Irradiation silicon samples that occurs over three decades of 10 keV x-ray irradiation. II. SAMPLE PREPARATION Silicon

Weiss, Sharon

72

ReaxFF SiO Reactive Force Field for Silicon and Silicon Oxide Systems  

Microsoft Academic Search

To predict the structures, properties, and chemistry of materials involving silicon and silicon oxides; interfaces between these materials; and hydrolysis of such systems, we have developed the ReaxFFSiO, reactive force field. The parameters for this force field were obtained from fitting to the results of quantum chemical (QC) calculations on the structures and energy barriers for a number of silicon

Adri C. T. van Duin; Alejandro Strachan; Shannon Stewman; Qingsong Zhang; Xin Xu; William A. Goddard

2003-01-01

73

Silicon surfaces : metallic character, oxidation and adhesion A. Cros (*)  

E-print Network

707 Silicon surfaces : metallic character, oxidation and adhesion A. Cros (*) IBM T.J. Watson of an ordered or disordered noble metal (Ag, Au) monolayer on the Si(111) surface has a great influence on the growth mode ofmetal atoms and the oxidation ofthe silicon surface atoms. These phenomena are discussed

Paris-Sud XI, Université de

74

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS  

E-print Network

CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS by David T. Oliphant. Woolley Dean, College of Physical and Mathematical Sciences #12;ABSTRACT CHARACTERIZATION OF URANIUM, URANIUM OXIDE AND SILICON MULTILAYER THIN FILMS David T. Oliphant Department of Physics and Astronomy

Hart, Gus

75

Study of thermophysical properties of crystalline silicon and silicon-rich silicon oxide layers  

NASA Astrophysics Data System (ADS)

The interaction of laser irradiation with SiOx films and process of decomposition SiOx on SiO2 and Si nanocrystals under the action of laser irradiation are investigated. Using the Comsol Multiphysics software package, the mathematical modeling of temperature distribution in a c-Si wafer and also on it's surface are carried out. It is shown that laser pulses can efficiently warm the samples of crystalline silicon. During the laser pulse of 10 ns with intensity of 52 MW/cm2 the temperature up to 2100 K can be reached on the sample surface. The experimental investigation of IR spectra of the initial and laser annealed silicon wafer coated with SiOx film confirmed the phase transformation of silicon oxide films. The changing electrical conductivity of films after laser irradiation points at changing of electron traps as a result of the film structure transformation.

Gavrylyuk, O. O.; Semchyk, O. Yu.; Bratus, O. L.; Evtukh, A. A.; Steblova, O. V.; Fedorenko, L. L.

2014-05-01

76

Nano-ridge fabrication by local oxidation of silicon edges with silicon nitride as a mask  

Microsoft Academic Search

A method to fabricate nano-ridges over a full wafer is presented. The fabrication method uses local oxidation of silicon, with silicon nitride as a mask, and wet anisotropic etching of silicon. The realized structures are 7-20 nm wide, 40-100 nm high and centimeters long. All dimensions are easily adjustable by varying the oxidation time, the wet etching time and the

Jeroen Haneveld; Erwin Berenschot; Pascale Maury; Henri Jansen

2006-01-01

77

Resistive switches and memories from silicon oxide.  

PubMed

Because of its excellent dielectric properties, silicon oxide (SiO(x)) has long been used and considered as a passive, insulating component in the construction of electronic devices. In contrast, here we demonstrate resistive switches and memories that use SiO(x) as the sole active material and can be implemented in entirely metal-free embodiments. Through cross-sectional transmission electron microscopy, we determine that the switching takes place through the voltage-driven formation and modification of silicon (Si) nanocrystals (NCs) embedded in the SiO(x) matrix, with SiO(x) itself also serving as the source of the formation of this Si pathway. The small sizes of the Si NCs (d ? 5 nm) suggest that scaling to ultrasmall domains could be feasible. Meanwhile, the switch also shows robust nonvolatile properties, high ON/OFF ratios (>10(5)), fast switching (sub-100-ns), and good endurance (10(4) write-erase cycles). These properties in a SiO(x)-based material composition showcase its potentials in constructing memory or logic devices that are fully CMOS compatible. PMID:20806916

Yao, Jun; Sun, Zhengzong; Zhong, Lin; Natelson, Douglas; Tour, James M

2010-10-13

78

Ceramic oxide coatings for the corrosion protection of silicon carbide  

SciTech Connect

Silicon carbide is currently used as a structural material for heat exchanger tubes and related applications because of its excellent thermal properties and oxidation resistance. Silicon carbide suffers corrosion degradation, however, in the aggressive furnace environments of industrial processes for aluminum remelting, advanced glass melting, and waste incineration. Adherent ceramic oxide coatings developed at Solar Turbines Incorporated, with the support of the Gas Research Institute, have been shown to afford corrosion protection to silicon carbide in a simulated aluminum remelt furnace environment as well as in laboratory-type corrosion testing. The coatings are also protective to silicon carbide-based ceramic matrix composites.

Roode, M. van; Price, J.R. (Solar Turbines Incorporated, San Diego, CA (United States)); Stala, C. (Salomon Brothers, New York, NY (United States))

1993-01-01

79

Nitric oxide-releasing porous silicon nanoparticles  

PubMed Central

In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment. PMID:25114633

2014-01-01

80

Direct comparison of the electrical properties in metal\\/oxide\\/nitride\\/oxide\\/silicon and metal\\/aluminum oxide\\/nitride\\/oxide\\/silicon capacitors with equivalent oxide thicknesses  

Microsoft Academic Search

We examine the electrical properties of metal\\/oxide\\/nitride\\/oxide\\/silicon (MONOS) capacitors with two different blocking oxides, SiO2 and Al2O3, under the influence of the same electric field. The thickness of the Al2O3 layer is set to 150 Å, which is electrically equivalent to a thickness of the SiO2 layer of 65 Å, in the MONOS structure for this purpose. The capacitor with the Al2O3

Ho-Myoung An; Yu Jeong Seo; Hee Dong Kim; Kyoung Chan Kim; Jong-Guk Kim; Won-Ju Cho; Jung-Hyuk Koh; Yun Mo Sung; Tae Geun Kim

2009-01-01

81

Modelling and engineering of stress based controlled oxidation effects for silicon nanostructures  

E-print Network

Modelling and engineering of stress based controlled oxidation effects for silicon nanostructures, 59046 France E-mail: christophe.krzeminski@isen.fr Abstract. Silicon nanostructure patterning-retarded oxidation phenomenon in various silicon nanostructures (nanobeams, nanorings and nanowires) both

Paris-Sud XI, Université de

82

Atomic force microscopy local oxidation of silicon nitride thin films for mask fabrication  

Microsoft Academic Search

Silicon nitride thin films deposited on silicon substrates are patterned by using atomic force microscopy (AFM) local oxidation nanolithography. The mechanism of the AFM-induced oxidation is studied by analysing the kinetics of the oxidation and by studying the electrical current during the oxidation process. We observe that the silicon substrate and the silicon nitride layer are simultaneously modified. Because of

Irene Fernandez-Cuesta; Xavier Borrisé; Francesc Pérez-Murano

2005-01-01

83

Laser-induced oxidation kinetics of bismuth surface microdroplets on GaAsBi studied in situ by Raman microprobe analysis.  

PubMed

We report the cw-laser-induced oxidation of molecular-beam-epitaxy grown GaAsBi bismuth surface microdroplets investigated in situ by micro-Raman spectroscopy under ambient conditions as a function of irradiation power and time. Our results reveal the surface droplets are high-purity crystalline bismuth and the resultant Bi2O3 transformation to be ?-phase and stable at room temperature. A detailed Raman study of Bi microdroplet oxidation kinetics yields insights into the laser-induced oxidation process and offers useful real-time diagnostics. The temporal evolution of new ?-Bi2O3 Raman modes is shown to be well described by Johnson-Mehl-Avrami-Kolmogorov kinetic transformation theory and while this study limits itself to the laser-induced oxidation of GaAsBi bismuth surface droplets, the results will find application within the wider context of bismuth laser-induced oxidation and direct Raman laser processing. PMID:25607191

Steele, J A; Lewis, R A

2014-12-29

84

Phase stability and microstructural evolution of bismuth strontium calcium copper oxide superconducting ceramic oxides  

NASA Astrophysics Data System (ADS)

The use of high-Tsb{c} superconductors in commercial applications requires that the superconducting properties be maximized. More importantly, easy and rapid synthesis of single phase materials is required. Although many different processing routes have been attempted, the true stabilities of the superconducting oxides have not been accurately examined. The current investigation of the phase stability limits of Bisb2Srsb2Casb1Cusb2Osb{8+x} involves examination of Bi-2212 powder processing, thermal analysis and materials characterization. The phase stability limits were investigated when the material was at thermal equilibrium. The oxygen non-stoichiometry was measured by thermal gravimetric analysis from 300sp°C to 1000sp°C in 3×10sp{-3} atm to 1.0 atm oxygen. Phase stability and decomposition reactions are documented. Additional microstructural evolution of phases is compared during thermal analysis of equilibrated specimens. The phase stability diagram for Bi-2212 as a function of oxygen partial pressure and temperature is determined. This diagram can be utilized to optimize the processing of this superconducting material. This research was supported by U.S. Department of Energy, Office of Basic Energy Sciences, and in part by the Midwest Superconductivity Consortium under DOE Grant No. DE-FG02-90ER45427.

Medendorp, Nicholas William, Jr.

1998-12-01

85

Indium oxide/n-silicon heterojunction solar cells  

DOEpatents

A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

Feng, Tom (Morris Plains, NJ); Ghosh, Amal K. (New Providence, NJ)

1982-12-28

86

Growth of silicon quantum dots by oxidation of the silicon nanocrystals embedded within silicon carbide matrix  

SciTech Connect

A moderately low temperature (?800 °C) thermal processing technique has been described for the growth of the silicon quantum dots (Si-QD) within microcrystalline silicon carbide (?c-SiC:H) dielectric thin films deposited by plasma enhanced chemical vapour deposition (PECVD) process. The nanocrystalline silicon grains (nc-Si) present in the as deposited films were initially enhanced by aluminium induced crystallization (AIC) method in vacuum at a temperature of T{sub v} = 525 °C. The samples were then stepwise annealed at different temperatures T{sub a} in air ambient. Analysis of the films by FTIR and XPS reveal a rearrangement of the ?c-SiC:H network has taken place with a significant surface oxidation of the nc-Si domains upon annealing in air. The nc-Si grain size (D{sub XRD}) as calculated from the XRD peak widths using Scherrer formula was found to decrease from 7 nm to 4 nm with increase in T{sub a} from 250 °C to 800 °C. A core shell like structure with the nc-Si as the core and the surface oxide layer as the shell can clearly describe the situation. The results indicate that with the increase of the annealing temperature in air the oxide shell layer becomes thicker and the nc-Si cores become smaller until their size reduced to the order of the Si-QDs. Quantum confinement effect due to the SiO covered nc-Si grains of size about 4 nm resulted in a photoluminescence peak due to the Si QDs with peak energy at 1.8 eV.

Kole, Arindam; Chaudhuri, Partha, E-mail: erpc@iacs.res.in [Indian Association for the Cultivation of Science, 2A and 2B Raja S.C. Mullick Road, Jadavpur, Kolkata-700032 (India)

2014-10-15

87

Sensitized broadband near-infrared luminescence from bismuth-doped silicon-rich silica films.  

PubMed

Developing Si compatible optical sources has attracted a great deal of attention owing to the potential for forming inexpensive, monolithic Si-based integrated devices. In this Letter, we show that ultra broadband near-IR (NIR) luminescence in the optical telecommunication window of silica optical fibers was obtained for Bi-doped silicon-rich silica films prepared by a co-sputtering method. Without excess Si, i.e., Bi-doped pure silica films, no luminescence was observed in the NIR range. A broad Bi-related NIR photoluminescence appears when excess Si was doped in the Bi-doped silica. The luminescence properties depended strongly on the amount of excess Si and the annealing temperature. Photoluminescence results suggest that excess Si acts as an agent to activate Bi NIR luminescence centers and also as an energy donor to transfer excitation energy to the centers. It is believed that this peculiar structure might find some important applications in Si photonics. PMID:22048371

Miwa, Yuji; Sun, Hong-Tao; Imakita, Kenji; Fujii, Minoru; Teng, Yu; Qiu, Jianrong; Sakka, Yoshio; Hayashi, Shinji

2011-11-01

88

Structural, electrical, and thermoelectric properties of bismuth telluride: Silicon/carbon nanocomposites thin films  

NASA Astrophysics Data System (ADS)

In this study, the effect of the presence of secondary phases on the structural, electrical, and thermoelectric properties of nanocomposite Bi2Te3 films prepared by co-sputtering of silicon and carbon with Bi2Te3 has been investigated. Growth temperature and the presence of Si and C phase are observed to have a strong effect on the topography and orientation of crystallites. X-ray diffraction study demonstrates that Bi2Te3 and Bi2Te3:C samples have preferred (0 0 15) orientation in comparison to Bi2Te3:Si sample, which have randomly oriented crystallites. Atomic force, conducting atomic force, and scanning thermal microscopy analysis show significant differences in topographical, electrical, and thermal conductivity contrasts in Bi2Te3:Si and Bi2Te3:C samples. Due to the randomly oriented crystallites and the presence of Si along the crystallite boundaries, appreciable Seebeck coefficient, higher electrical conductivity, and lower thermal conductivity is achieved resulting in relatively higher value of power factor (3.71 mW K-2 m-1) for Bi2Te3:Si sample. This study shows that by incorporating a secondary phase along crystallite boundaries, microstructural, electrical, and thermoelectric properties of the composite samples can be modified.

Agarwal, Khushboo; Mehta, B. R.

2014-08-01

89

I. Electroluminescence from Hydrogen Uranyl Phosphate. I. Indium-Substituted Bismuth Copper Oxide Superconductors  

NASA Astrophysics Data System (ADS)

Chapter 1. A review of the general aspects of solid electrolytes is presented along with a summary of the electrical and optical properties of hydrogen uranyl phosphate (HUO_2PO_4 bullet4H_2O, HUP). A review of impedance spectroscopy, as it relates to the determination of ionic conductivities and dielectric constants of solid electrolytes is presented. The final section covers some aspects of gas plasma display devices. Chapter 2. Electroluminescence (EL) cells have been constructed with the ionically conducting solid HUP as the emissive medium. With ac excitation, both uranyl emission and molecular nitrogen plasma emission are observed, with the latter appearing to excite the former. Similar results were obtained with fully-substituted sodium (NaUP), magnesium (Mg_{0.5}UP), and pyridinium (pyHUP) derivatives of HUP. For all of these solids, the dependence of the EL intensity on sample thickness, ac frequency, and applied voltage has been determined. Impedance measurements permitted acquisition of dielectric constants and ionic conductivities for these solids, both of which decrease in the order HUP > NaUP > Mg_{0.5}UP > pyHUP. A model describing the dependence of EL intensity on cell parameters is presented. Chapter 3. The copper oxide superconductors can be structurally classified into five major families, represented by the compositions, (La,Sr)_2CuO _4, YBa_2Cu_3O_7, Pb_2Sr_2(Y,Ca)Cu_3O_8, (TIO)_{m}Ca_{n-1}Ba_2Cu _{n}O_{2n+2}, and Bi_2Sr_2(Ln_{1-x}Ce _{x})_2Cu_2O_{10+y }. All families are linked by a CuO _2 layer, which is crucial for superconductivity. The structural and chemical aspects of each family is covered with emphasis on the bismuth and thallium systems. The effects of substitution and oxygen annealing are also briefly considered. Chapter 4. The attempted substitution of indium into the rm Bi_2(Ca,Sr)_2CuO _6 and Bi_2(Ca,Sr) _3Cu_2O _8 systems is reported. Previously unreported side products, (Ca,Sr)In_2O _4 and Bi-Ca-Sr-O, viz., produced in the attempted reactions, hinder the formation of an indium -containing product. The T_{rm c} are within the range expected for the parent materials. A novel synthetic procedure based on nitrate decomposition was developed, which yielded two meta-stable phases, Bi-Ca-O and Bi_{2 -x}In_{x}O_3; the former is related to the Bi-Ca-Sr-O phase and the latter decomposes in a complex manner. Substitution was accomplished in the rm Bi_2Sr_2Sm_{1.7 }Ce_{0.3}Cu_2O_{10 } system, but the products were not superconducting.

Dieckmann, Gunnar Rudolph

1990-01-01

90

Fracture phenomenology of a sintered silicon nitride containing oxide additives  

Microsoft Academic Search

Crack propagation mechanisms in a sintered silicon nitride containing various oxide additives (ceria, magnesia, zirconia and strontium oxide) were studied as a function of initial flaw size, temperature, applied stress and time. Surface cracks of controlled size were introduced using the microhardness indentation-induced-flaw technique. At 20° C, the fracture stress was found to depend on initial crack size according to

R. K. Govila

1988-01-01

91

One-step synthesis of bismuth molybdate catalysts via flame spray pyrolysis for the selective oxidation of propylene to acrolein.  

PubMed

Flame spray pyrolysis (FSP) of Bi(iii)- and Mo(vi)-2-ethylhexanoate dissolved in xylene resulted in various nanocrystalline bismuth molybdate phases depending on the Bi/Mo ratio. Besides ?-Bi2Mo3O12 and ?-Bi2MoO6, FSP gave direct access to the metastable ?-Bi2Mo2O9 phase with high surface area (19 m(2) g(-1)). This phase is normally only obtained at high calcination temperatures (>560 °C) resulting in lower surface areas. The ?-phase was stable up to 400 °C and showed superior catalytic performance compared to ?- and ?-phases in selective oxidation of propylene to acrolein at temperatures relevant for industrial applications (360 °C). PMID:25350295

Schuh, K; Kleist, W; Høj, M; Trouillet, V; Jensen, A D; Grunwaldt, J-D

2014-12-18

92

Compact and low-latency instantaneous frequency measurement using 38 cm bismuth-oxide fiber and fiber Bragg gratings.  

PubMed

We demonstrated a compact and low-latency photonic approach for broadband RF signal frequency measurement. The photonic approach does not require high-speed electronics for gigahertz RF signal measurement. Frequency-to-intensity mapping is achieved based on a two-tap finite-impulse-response filter architecture, where the time delay between signals is provided by fiber Bragg grating array. With four-wave mixing (FWM) as an optical broadband mixer, sinusoid frequency response is transferred to a DC output, where FWM is achieved in a 38 cm bismuth-oxide fiber. Thus, the resultant signal does not consist of any high-frequency component and no high-speed oscilloscope is needed for the measurement. PMID:23938415

Fok, Mable P

2013-08-10

93

Zinc oxide varistors and/or resistors  

DOEpatents

Varistors and/or resistors are described that include doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

1993-07-27

94

Zinc oxide varistors and/or resistors  

DOEpatents

Varistors and/or resistors that includes doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

1993-01-01

95

Structure-property relationships of new bismuth and lead oxide based perovskite ternary solid solutions  

NASA Astrophysics Data System (ADS)

Two new bismuth and lead oxide based perovskite ternary solid solutions, namely xBi(Zn1/2Ti1/2)O3-yPbZrO3-zPbTiO3 [xBZT-yPZ-zPT] and xBi(Mg1/2Ti1/2)O3-yBi(Zn 1/2Ti1/2)O3-zPbTiO3 [xBMT-yBZT-zPT] have been developed and their structural and electrical properties have been determined. Various characterization techniques such as X-ray diffraction, calorimetery, electron microscopy, dielectric and piezoelectric measurements have been performed to determine the details of the phase diagram, crystal structure, and domain structure. The selection of these materials is based on the hypothesis that the presence of BZT-PT (Case I ferroelectric (FE)) will increase the transition temperature of MPB systems BMT-PT (Case II FE), and PZ-PT (Case III FE), and subsequently a MPB will be observed in the ternary phase diagrams. The Case I, II, and III classification has been outlined by Stringer et al., is on the basis of the transition temperatures (TC) behavior with composition in the Bi and Pb oxide based binary systems. Several pseudobinary lines have been investigated across the xBZT-yPZ-zPT ternary phase diagram which exhibit varied TC behavior with composition, showing both Case I- and Case III-like TC trends in different regions. A MPB between rhombohedral to tetragonal phases has been located on a pseudobinary line 0.1BZT-0.9[xPT-(1-x)PZ]. Compositions near MPB exhibit mainly soft PZT-like properties with the TC around 60°C lower than the unmodified PZT near its MPB. Electrical properties are reported for the MPB composition, TC = 325°C, Pr = 35 microC/cm2, d33 = 300 pC/N and kP =0.45. Rhombohedral compositions show diffuse phase transition with small frequency dispersion, similar to relaxors. Two transition peaks in the permittivity as well as in the latent heat has been observed in some compositions near the BZT-PT binary. This leads to the speculation for the existence of miscibility gap in the solid solutions in these regions. Transmission electron microscopy (TEM) performed on these compositions show subdomain modulation contrast suggesting the presence of localized and correlated spatial fluctuations in the spontaneous strain. In the xBMT-yBZT-zPT system, very small rhombohedral region in the room temperature phase diagram has been observed. Owing to the limited solid solubility, only a part of the phase diagram could be explored. Compositions on pseudobinary xPT-(1-x)[0.9BMT-0.1BZT] has been successfully fabricated and characterized. High c/a ratio of 1.04 has been observed for a surprisingly low tolerance factor of 0.9732. Transition temperature trends have been established from DSC and dielectric data along this pseudobinary line. The following trend in the TC has been observed with the increase in non PT end member that has been divided into three zones: in Zone I TC increases, in Zone II it decreases, and in the Zone III, two transition temperatures are observed. From the TEM investigation, it has been noted that these compositions exhibit subdomain modulations which reflects the presence of spontaneous strain. These modulations increase with the increase in non PT end member, and at certain composition along pseudobinary, both macro and micro domains structure can be observed. Compositions in the rhombohedral phase of xBMT-yBZT-zPT show dramatic changes in dielectric and piezoelectric properties when quenched from high temperature. Samples quenched from temperature range 650°C-900°C show classical ferroelectric switching behavior, which is not observed on either side of this temperature range. These quenched states are however, unstable in nature and lose their ferroelectric properties when heated to a temperature as low as 400°C. Structural analysis by TEM shows varied domain structures for samples quenched from different temperatures. Evidences of tilt transitions and intermediate phases have also been observed in the TEM study. New insights into solid solution development and defect metastability are gained and discussed in relation to relaxor based ferroelectric phenomena. Complex domains and intermediate displ

Dwivedi, Akansha

96

A review of oxide, silicon nitride, and silicon carbide brazing  

SciTech Connect

There is growing interest in using ceramics for structural applications, many of which require the fabrication of components with complicated shapes. Normal ceramic processing methods restrict the shapes into which these materials can be produced, but ceramic joining technology can be used to overcome many of these limitations, and also offers the possibility for improving the reliability of ceramic components. One method of joining ceramics is by brazing. The metallic alloys used for bonding must wet and adhere to the ceramic surfaces without excessive reaction. Alumina, partially stabilized zirconia, and silicon nitride have high ionic character to their chemical bonds and are difficult to wet. Alloys for brazing these materials must be formulated to overcome this problem. Silicon carbide, which has some metallic characteristics, reacts excessively with many alloys, and forms joints of low mechanical strength. The brazing characteristics of these three types of ceramics, and residual stresses in ceramic-to-metal joints are briefly discussed.

Santella, M.L.; Moorhead, A.J.

1987-01-01

97

Nanostructured bismuth vanadate-based materials for solar-energy-driven water oxidation: a review on recent progress.  

PubMed

Water oxidation is the key step for both photocatalytic water splitting and CO? reduction, but its efficiency is very low compared with the photocatalytic reduction of water. Bismuth vanadate (BiVO?) is the most promising photocatalyst for water oxidation and has become a hot topic for current research. However, the efficiency achieved with this material to date is far away from the theoretical solar-to-hydrogen conversion efficiency, mainly due to the poor photo-induced electron transportation and the slow kinetics of oxygen evolution. Fortunately, great breakthroughs have been made in the past five years in both improving the efficiency and understanding the related mechanism. This review is aimed at summarizing the recent experimental and computational breakthroughs in single crystals modified by element doping, facet engineering, and morphology control, as well as macro/mesoporous structure construction, and composites fabricated by homo/hetero-junction construction and co-catalyst loading. We aim to provide guidelines for the rational design and fabrication of highly efficient BiVO?-based materials for water oxidation. PMID:25325232

Huang, Zhen-Feng; Pan, Lun; Zou, Ji-Jun; Zhang, Xiangwen; Wang, Li

2014-11-01

98

Thermal oxidation of 3C silicon carbide single-crystal layers on silicon  

Microsoft Academic Search

Thermal oxidation of thick single-crystal 3C SiC layers on silicon substrates was studied. The oxidations were conducted in a wet O2 atmosphere at temperatures from 1000 to 1250 C for times from 0.1 to 50 h. Ellipsometry was used to determine the thickness and index of refraction of the oxide films. Auger analysis showed them to be homogeneous with near

C. D. Fung; J. J. Kopanski

1984-01-01

99

Viscous properties of aluminum oxide nanotubes and aluminium oxide nanoparticles - silicone oil suspensions  

Microsoft Academic Search

Electrorheological (ER) fluids consisting of gamma-aluminum oxide nanotubes and gamma-aluminum oxide nanoparticles dispersed within silicone oil were prepared. The relationship between shear stress and shear rate was measured and theoretically simulated by using an extended Bingham model for both the rheological and electrorheological features of these systems. Shear stress and viscosity showed a sharp increase for the aluminum oxide nanotubes

Ram Thapa; Steven French; Adrian Delgado; Carlos Ramos; Jose Gutierrez; Mircea Chipara; Karen Lozano

2010-01-01

100

Ion implantation reduces radiation sensitivity of metal oxide silicon /MOS/ devices  

NASA Technical Reports Server (NTRS)

Implanting nitrogen ions improves hardening of silicon oxides 30 percent to 60 percent against ionizing radiation effects. Process reduces sensitivity, but retains stability normally shown by interfaces between silicon and thermally grown oxides.

1971-01-01

101

An atomistic insight into the corrosion of the oxide film in liquid lead-bismuth eutectic.  

PubMed

When used as a protective scale, the Fe3O4 layer covering the stainless steel surface in accelerator driven subcritical systems (ADS) is corroded by liquid lead-bismuth eutectics (LBE). By performing theoretical calculations, we reveal that both Pb and Bi at the interface between the LBE and the Fe3O4 scale, favorably adsorb onto the Fe3O4 surfaces, weakening the strength of Fe-O bonds nearby significantly. This facilitates the movement of iron atoms toward the deposited Pb(Bi) and away from the Fe3O4 surface, thus causing corrosion. Such corrosion behavior becomes severe if oxygen vacancies exist in the surface region. PMID:24626636

Li, Dongdong; Song, Chi; He, H Y; Liu, C S; Pan, B C

2014-04-28

102

UNCORRECTEDPROOF 2 Optical properties of bismuth borate glasses  

E-print Network

UNCORRECTEDPROOF 2 Optical properties of bismuth borate glasses 3 Isabella-Ioana Oprea, Hartmut in the binary system bismuth oxide (Bi2O3)­boric oxide (B2O3) are measured for the composition 8 range 25­65 mol.70.Ce; 78.20.Ci 13 Keywords: Bismuth borate; Glass; Refractive index; Optical properties 14 1

Osnabrück, Universität

103

Hole-blocking titanium-oxide/silicon heterojunction and its application to photovoltaics  

E-print Network

Hole-blocking titanium-oxide/silicon heterojunction and its application to photovoltaics Sushobhan-bandgap semiconducting heterojunctions on silicon. Here, we present a wide-bandgap heterojunction--between titanium oxide and crystalline silicon--where the titanium oxide is deposited via a metal-organic chemical vapor deposition

104

Stress-enhanced oxidation of silicon nitride ceramics  

Microsoft Academic Search

Silicon nitride ceramics show an accelerated oxidation rate under load in air. This phenomenon was observed for porous and dense ceramics with and without additives in a wide temperature range (700--1,450 C) and can be interpreted as stress corrosion in oxygen-containing environments. Stresses cause an alteration of the amount and composition of oxidation products, formation of pits and cracks on

Yury G. Gogotsi; Georg Grathwohl

1993-01-01

105

Oxidation of silicon nitride in a wet atmosphere  

Microsoft Academic Search

The effect of water vapour on oxidation was studied with hot-pressed silicon nitride containing both yttria and alumina as\\u000a sintering aids in wet air flow with 10, 20, 30, and 40 vol% H2O at 1300C for 100 h. The oxidation kinetics were determined in a wet air flow with 20 vol% H2O and in a dry air flow at 1300C

Minoru Maeda; Kazuo Nakamura; Tsutomu Ohkubo

1989-01-01

106

Y-Ba-Cu-O superconducting film on oxidized silicon  

SciTech Connect

We report thick superconducting films of Y-Ba-Cu-O on oxidized silicon substrates. The critical temperatures for onset and zero resistance are 96 and 77 K, respectively. X-ray diffraction analysis predicts 1, 2, 3 composition and orthorhombic phase of the film.

Gupta, R.P.; Khokle, W.S.; Dubey, R.C.; Singhal, S.; Nagpal, K.C.; Rao, G.S.T.; Jain, J.D.

1988-06-06

107

Electron-stimulated oxidation of silicon carbide  

Microsoft Academic Search

Auger Electron spectroscopy was used to study electron-stimulated oxidation (ESO) of SiC. The rate of oxidation was investigated as a function of electron-beam exposure (on and off), primary electron-beam energy (3–6keV), electron-beam current (25–500nA) and total chamber pressure. The oxidation rate correlated with overall chamber pressure rather than the partial pressure of H2O, CO or CO2 alone. The rate decreased

G. Y. McDaniel; S. T. Fenstermaker; D. E. Walker; W. V. Lampert; S. M. Mukhopadhyay; P. H. Holloway

2000-01-01

108

One dimensional silicon nanostructures prepared by oxidized porous silicon under heat treatment  

NASA Astrophysics Data System (ADS)

One dimensional high aspect ratio Si nanostructures were prepared by using oxidized sponge like nanostructured porous silicon (pSi) as a seed material. This can be considered as a complementary technique to synthesize silicon nanowires such as vapour-liquid-solid method (VLS). One dimensional silicon nanostructures were fabricated by subjecting pSi to heat treatment without metal assistance. It is shown that the aspect ratio can be tuned by controlling the concentration of oxygen (SiO2) and the porosity of the seed material (pSi). The atomic percentage of oxygen incorporated into pSi was estimated by Energy Dispersive X-ray Spectroscopy (EDS). Field Emission Scanning Electron Microscope (FESEM) confirms unambiguously the formation of silicon nanowires. The broad peak observed around 490 cm-1 in Raman spectra further confirms the formation of Si NWs. At higher oxygen concentration, narrower (?20 nm) and longer (?1 ?m) silicon nanowires have been achieved. The observed change in photoluminescence (PL) peak position towards lower wavelength as a function of the aspect ratio of Si NWs is in good agreement with quantum confinement effects. This work demonstrates a new oxide assisted method to prepare high aspect ratio silicon nanowires without using any metal catalysts.

Vendamani, V. S.; Pathak, A. P.; Rao, S. V. S. Nageswara

2014-11-01

109

Nonlinear optical properties of low temperature annealed silicon-rich oxide and silicon-rich nitride materials for silicon photonics  

SciTech Connect

We investigate the nonlinear optical properties of Si-rich silicon oxide (SRO) and Si-rich silicon nitride (SRN) samples as a function of silicon content, annealing temperature, and excitation wavelength. Using the Z-scan technique, we measure the non-linear refractive index n{sub 2} and the nonlinear absorption coefficient {beta} for a large number of samples fabricated by reactive co-sputtering. Moreover, we characterize the nonlinear optical parameters of SRN in the broad spectral region 1100-1500 nm and show the strongest nonlinearity at 1500 nm. These results demonstrate the potential of the SRN matrix for the engineering of compact devices with enhanced Kerr nonlinearities for silicon photonics applications.

Minissale, S. [Photonics Center, Boston University, 8 Saint Mary's street, Boston, Massachusetts 02215-2421 (United States) and Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States); Yerci, S. [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States); Dal Negro, L. [Photonics Center, Boston University, 8 Saint Mary's street, Boston, Massachusetts 02215-2421 (United States) and Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Brookline, Massachusetts 02446 (United States); Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215-2421 (United States)

2012-01-09

110

Effect of reaction mechanism on precursor exposure time in atomic layer deposition of silicon oxide and silicon nitride.  

PubMed

Atomic layer deposition (ALD) of highly conformal, silicon-based dielectric thin films has become necessary because of the continuing decrease in feature size in microelectronic devices. The ALD of oxides and nitrides is usually thought to be mechanistically similar, but plasma-enhanced ALD of silicon nitride is found to be problematic, while that of silicon oxide is straightforward. To find why, the ALD of silicon nitride and silicon oxide dielectric films was studied by applying ab initio methods to theoretical models for proposed surface reaction mechanisms. The thermodynamic energies for the elimination of functional groups from different silicon precursors reacting with simple model molecules were calculated using density functional theory (DFT), explaining the lower reactivity of precursors toward the deposition of silicon nitride relative to silicon oxide seen in experiments, but not explaining the trends between precursors. Using more realistic cluster models of amine and hydroxyl covered surfaces, the structures and energies were calculated of reaction pathways for chemisorption of different silicon precursors via functional group elimination, with more success. DFT calculations identified the initial physisorption step as crucial toward deposition and this step was thus used to predict the ALD reactivity of a range of amino-silane precursors, yielding good agreement with experiment. The retention of hydrogen within silicon nitride films but not in silicon oxide observed in FTIR spectra was accounted for by the theoretical calculations and helped verify the application of the model. PMID:24915469

Murray, Ciaran A; Elliott, Simon D; Hausmann, Dennis; Henri, Jon; LaVoie, Adrien

2014-07-01

111

Tribological interaction between polytetrafluoroethylene and silicon oxide surfaces  

NASA Astrophysics Data System (ADS)

We investigated the tribological interaction between polytetrafluoroethylene (PTFE) and silicon oxide surfaces. A simple rig was designed to bring about a friction between the surfaces via sliding a piece of PTFE on a thermally oxidized silicon wafer specimen. A very mild inclination (˜0.5°) along the sliding motion was also employed in order to monitor the tribological interaction in a gradual manner as a function of increasing contact force. Additionally, some patterns were sketched on the silicon oxide surface using the PTFE tip to investigate changes produced in the hydrophobicity of the surface, where the approximate water contact angle was 45° before the transfer. The nature of the transferred materials was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS results revealed that PTFE was faithfully transferred onto the silicon oxide surface upon even at the slightest contact and SEM images demonstrated that stable morphological changes could be imparted onto the surface. The minimum apparent contact pressure to realize the PTFE transfer is estimated as 5 kPa, much lower than reported previously. Stability of the patterns imparted towards many chemical washing processes lead us to postulate that the interaction is most likely to be chemical. Contact angle measurements, which were carried out to characterize and monitor the hydrophobicity of the silicon oxide surface, showed that upon PTFE transfer the hydrophobicity of the SiO2 surface could be significantly enhanced, which might also depend upon the pattern sketched onto the surface. Contact angle values above 100° were obtained.

Uçar, A.; ?opuro?lu, M.; Baykara, M. Z.; Ar?kan, O.; Suzer, S.

2014-10-01

112

Tribological interaction between polytetrafluoroethylene and silicon oxide surfaces.  

PubMed

We investigated the tribological interaction between polytetrafluoroethylene (PTFE) and silicon oxide surfaces. A simple rig was designed to bring about a friction between the surfaces via sliding a piece of PTFE on a thermally oxidized silicon wafer specimen. A very mild inclination (~0.5°) along the sliding motion was also employed in order to monitor the tribological interaction in a gradual manner as a function of increasing contact force. Additionally, some patterns were sketched on the silicon oxide surface using the PTFE tip to investigate changes produced in the hydrophobicity of the surface, where the approximate water contact angle was 45° before the transfer. The nature of the transferred materials was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS results revealed that PTFE was faithfully transferred onto the silicon oxide surface upon even at the slightest contact and SEM images demonstrated that stable morphological changes could be imparted onto the surface. The minimum apparent contact pressure to realize the PTFE transfer is estimated as 5 kPa, much lower than reported previously. Stability of the patterns imparted towards many chemical washing processes lead us to postulate that the interaction is most likely to be chemical. Contact angle measurements, which were carried out to characterize and monitor the hydrophobicity of the silicon oxide surface, showed that upon PTFE transfer the hydrophobicity of the SiO2 surface could be significantly enhanced, which might also depend upon the pattern sketched onto the surface. Contact angle values above 100° were obtained. PMID:25362327

Uçar, A; Çopuro?lu, M; Baykara, M Z; Ar?kan, O; Suzer, S

2014-10-28

113

Electron-stimulated oxidation of silicon carbide  

NASA Astrophysics Data System (ADS)

Auger Electron spectroscopy was used to study electron-stimulated oxidation (ESO) of SiC. The rate of oxidation was investigated as a function of electron-beam exposure (on and off), primary electron-beam energy (3-6 keV), electron-beam current (25-500 nA) and total chamber pressure. The oxidation rate correlated with overall chamber pressure rather than the partial pressure of H2O, CO or CO2 alone. The rate decreased as the primary-beam voltage Ep was increased. The oxidation rate increased as the primary-beam current was increased at higher pressures (2.2×10-7 Torr). Oxidation did not occur in the absence of the electron beam.

McDaniel, G. Y.; Fenstermaker, S. T.; Walker, D. E.; Lampert, W. V.; Mukhopadhyay, S. M.; Holloway, P. H.

2000-01-01

114

Q-switched fibre laser using 21 cm Bismuth-erbium doped fibre and graphene oxide as saturable absorber  

NASA Astrophysics Data System (ADS)

A compact, Q-switched fibre laser is proposed and demonstrated using a compact Bismuth-based erbium doped fibre (Bi-EDF) together with a Graphene Oxide (GO) Saturable Absorber (SA). The 21 cm long Bi-EDF has an erbium dopant concentration of 6300 ppm with absorption rates of about 83 and 133 dB/m at 1480 and 1530 nm. The SA is fabricated from graphene flakes dissolved in water, forming a GO film that is sandwiched between two FC/PC connectors. The Q-switched Bi-EDF laser has an Amplified Spontaneous Emission (ASE) spectrum of 120 nm, stretching from 1490 to 1610 nm and a Q-switching threshold power of about 65 mW. At the maximum pump power of 118 mW, the pulses are generated with an average output power and pulse energy of 0.11 mW and 4.3 nJ, with a repetition rate and pulse width of 27.2 kHz and 7.7 ?s. The output can be tuned over the amplified spontaneous emission spectrum with an average peak power of about -16.8 dBm, and observation under a radio frequency spectrum analyser shows a highly stable output at 21.8 kHz. The proposed Bi-EDF laser will have substantial uses in applications requiring short and stable pulses such as rangefinding and sensing.

Ahmad, Harith; Zulkifli, Ahmad Zarif; Kiat, Yap Yuen; Harun, Sulaiman Wadi

2014-01-01

115

Enhancement of radiation effects by bismuth oxide nanoparticles for kilovoltage x-ray beams: A dosimetric study using a novel multi-compartment 3D radiochromic dosimeter  

NASA Astrophysics Data System (ADS)

The aim of this study is to present the first experimental validation and quantification of the dose enhancement capability of bismuth oxide nanoparticles (Bi2O3-Nps). A recently introduced multi-compartment 3D radiochromic dosimeter for measuring radiation dose enhancement produced from the interaction of X-rays with metal nanoparticles was employed to investigate the 3D spatial distribution of ionizing radiation dose deposition. Dose-enhancement factor for the dosimeters doped with Bi2O3-NPs was ~1.9 for both spectrophotometry and optical CT analyses. Our results suggest that bismuth-based nanomaterials are efficient dose enhancing agents and have great potential for application in clinical radiotherapy.

Alqathami, M.; Blencowe, A.; Yeo, U. J.; Franich, R.; Doran, S.; Qiao, G.; Geso, M.

2013-06-01

116

Lateral epitaxial overgrowth of silicon over recessed oxide  

NASA Astrophysics Data System (ADS)

A silicon-on-insulator (SOI) technique, lateral epitaxial overgrowth (LEO), which has applications in VSLI and which provides material for 3-D circuits is described. It is shown that LEO of silicon in a recessed oxide structure results in a lateral to vertical growth ratio greater than five. The technique is particularly applicable if the application of SOI is for dielectric isolation and radiation hardness. Initial experiments with Rutherford backscattering spectrometry show that LEO-SOI films obtained by this technique have very good crystallinity.

Jayadev, T. S.; Okazaki, E.; Petersen, H.; Millman, M.

1985-04-01

117

JOURNAL OF MATERIALS SCIENCE 29 (1994) 4135-4151 Bismuth oxide-based solid electrolytes for  

E-print Network

temperatures (~ 700 ~ or above) employ either a mixed molten carbonate or ceramic solid oxide as the electrolyte and are accordingly known as the molten carbonate fuel cells (MCFCs) and the solid oxide fuel molten salt as the working medium is more prone to creep and corrosion than metals and ceramics

Azad, Abdul-Majeed

118

Processing dependence of metal/tunnel-oxide/silicon junctions  

NASA Technical Reports Server (NTRS)

The effects of process variations on the fixed-charge density, interface-state density, and tunneling properties of tunnel oxides on (100) silicon are discussed. Annealing the oxide in nitrogen reduces the fixed-charge and interface-state densities substantially, but also causes a marked increase in oxide capacitance. Anneals in forming gas before metallization alter the interface-state distribution and decrease the insulating qualities of the tunneling oxides. Postmetallization anneals in forming gas reduce the interface-state density to 1 x 10 to the 11th e/sq cm V or below, and appear not to affect the current through the oxide. No evidence for metal-induced interface states is observed.

Dressendorfer, P. V.; Lai, S. K.; Barker, R. C.; Ma, T. P.

1980-01-01

119

Indium tin oxide and the amorphous-crystalline silicon heterojunction  

NASA Astrophysics Data System (ADS)

Amorphous silicon-crystalline silicon heterojunctions were prepared using the DC saddle-field plasma enhanced chemical vapour deposition (DCSF-PECVD) technique followed by RF magnetron sputtering of an indium tin oxide (ITO) layer on the nano-thin amorphous film. Depth dependent time of flight secondary ion mass spectrometry (ToF-SIMS) analysis was carried out in order to examine the compositional influence of the sputtered ITO on the underlying amorphous silicon layers. Three samples were analyzed: one, as deposited, a-Si:H/c-Si heterojunction; two, ITO covered a-Si:H/c-Si heterojunction; and three, similar to sample two but now dipped in 10% HCl in order to etch the ITO prior to SIMS analysis. The pre-treatment of the third sample was done to de-couple potential SIMS sputtering-induced implantation of indium, tin, and oxygen in the underlying silicon layers. SIMS analysis shows indium, tin, and oxygen below the surface of the silicon in both the etched and as-deposited samples. AFM analysis of all the samples was also done, indicating that the ITO surface has a high degree of roughness, which could make uniform etching more difficult and could potentially lead to small residual ITO spots on the surface, creating or enhancing the appearance of mixing in the SIMS results for the etched sample.

Halliop, Basia; Gougam, Adel; Kherani, Nazir P.; Zukotynski, Stefan

2010-06-01

120

Ferroelectric and dielectric properties of strontium bismuth niobate vanadates  

E-print Network

Ferroelectric and dielectric properties of strontium bismuth niobate vanadates Yun Wu and Guozhong 19 November 1999; accepted 20 April 2000) Strontium bismuth niobate vanadates, SrBi2(VxNb1-x)2O9 qualitatively different nondestructive read op- erations.3 Recently, bismuth oxide layered perovskite materials

Cao, Guozhong

121

Processing and Properties of Strontium Bismuth Vanadate Niobate Ferroelectric Ceramics  

E-print Network

Processing and Properties of Strontium Bismuth Vanadate Niobate Ferroelectric Ceramics Yun Wu, Chau, microstructure, and dielectric properties of strontium bismuth niobate vanadate ceramics, SrBi2(VxNb1 x)2O9 (SBVN. Introduction RECENTLY, bismuth-oxide-layered perovskite materials, such as SrBi2Nb2O9 (SBN), SrBi2Ta2O9 (SBT

Cao, Guozhong

122

Influence of Heat Treatment on Aluminum Oxide Films on Silicon  

Microsoft Academic Search

Properties of aluminum oxide films deposited on silicon by hydrolysis of AlCl3 depend on the growth temperatures. The influence of subsequent heat treatments on the film properties and structures have been investigated in films grown at 700 and 830°C. Etch rates and electron-diffraction patterns indicated that the properties of the films grown at 700°C were not converted to those of

M. Kamoshida; I. V. Mitchell; J. W. Mayer

1972-01-01

123

New perspectives on thermal and hyperthermal oxidation of silicon surfaces  

NASA Astrophysics Data System (ADS)

The growth of (ultra)thin silica (SiO2) layers on crystalline silicon (c-Si) and controlling the thickness of SiO2 is an important issue in the fabrication of microelectronics and photovoltaic devices (e.g., MOSFETs, solar cells, optical fibers etc.). Such ultrathin oxide can be grown and tuned even at low temperature (including room temperature), by hyperthermal oxidation or when performed on non-planar Si surfaces (e.g., Si nanowires or spheres). However, hyperthermal silica growth as well as small Si-NW oxidation in general and the initial stages in particular have not yet been investigated in full detail. This work is therefore devoted to controlling ultrathin silica thickness on planar and non-planar Si surfaces, which can open new perspectives in nanodevice fabrication. The simulation of hyperthermal (1-100 eV) Si oxidation demonstrate that at low impact energy (<10 eV), oxygen does not damage the Si surface and this energy region could thus beneficially be used for Si oxidation. In contrast to thermal oxidation, 10 eV species can directly oxidize Si subsurface layers. A transition temperature of about 700 K was found: below this temperature, the oxide thickness only depends on the impact energy of the impinging species. Above this temperature, the oxide thickness depends on the impact energy, type of oxidant and the surface temperature. The results show that control over the ultrathin oxide (a-SiO2) thickness is possible by hyperthermal oxidation of silicon surfaces at temperatures below the transition temperature. In small Si-NWs, oxidation is a self-limiting process that occurs at low temperature, resulting in small Si core - SiO2 shell (semiconductor + dielectric) or c-Si|SiOx| a-SiO2 nanowire, which has also being envisaged to be used as nanowire field-effect transistors and photovoltaic devices in near-future nanotechnology. Above the transition temperature such core-shell nanowires are completely converted to a-SiO2 nanowires. It can be concluded that an accurate control over the interfacial stress by choosing a suitable oxidation temperature and Si-NW diameter can lead to precise nanoscale control over the Si-core radius. All investigations were carried out by applying molecular dynamics calculations using the ReaxFF potential, allowing a accurately study of the underpinning physical and chemical processes.

Khalilov, Umedjon

124

Silver oxide nanostructure prepared on porous silicon for optoelectronic application  

NASA Astrophysics Data System (ADS)

The thermal evaporation system type (Edwards) has been used to evaporate high purity (99.9 %) silver on glass, n- and p-type silicon and porous silicon substrates at room temperature under low pressure (about 10-6 torr) for different thickness (50, 75, 100, 125 and 150 nm). Using a rapid thermal oxidation of Ag film at oxidation temperature 350 °C and different oxidation times, Ag2O thin film was prepared. The structural properties of Ag2O film were investigated and compared with other published results. The structural investigation showed that the films formed at thickness 100 nm showed (111) strong reflection along with weak reflections of (101) corresponding to the growth of single phase Ag2O with cubic structure. Dark and illuminated I-V of p-Ag2O/p-Si, p-Ag2O/n-Si, Al/p-PSi/Al, Al/n-PSi/Al, p-Ag2O/p-PSi/c-Si and p-Ag2O/n-PSi/c-Si heterojunction were investigated, discussed and prepared at optimum condition (oxidation temperature 350 °C and 90 s oxidation time with thickness 100 nm). Ohmic contacts were fabricated by evaporating 99.999 purity silver wires for back and aluminum wires for front contact, respectively.

Hassan, Marwa Abdul Muhsien; Agool, Ibrahim Ramdan; Raoof, Lamyaa Mohammed

2013-04-01

125

Silver oxide nanostructure prepared on porous silicon for optoelectronic application  

NASA Astrophysics Data System (ADS)

The thermal evaporation system type (Edwards) has been used to evaporate high purity (99.9 %) silver on glass, n- and p-type silicon and porous silicon substrates at room temperature under low pressure (about 10-6 torr) for different thickness (50, 75, 100, 125 and 150 nm). Using a rapid thermal oxidation of Ag film at oxidation temperature 350 °C and different oxidation times, Ag2O thin film was prepared. The structural properties of Ag2O film were investigated and compared with other published results. The structural investigation showed that the films formed at thickness 100 nm showed (111) strong reflection along with weak reflections of (101) corresponding to the growth of single phase Ag2O with cubic structure. Dark and illuminated I-V of p-Ag2O/ p-Si, p-Ag2O/ n-Si, Al/ p-PSi/Al, Al/ n-PSi/Al, p-Ag2O/ p-PSi/c-Si and p-Ag2O/ n-PSi/c-Si heterojunction were investigated, discussed and prepared at optimum condition (oxidation temperature 350 °C and 90 s oxidation time with thickness 100 nm). Ohmic contacts were fabricated by evaporating 99.999 purity silver wires for back and aluminum wires for front contact, respectively.

Hassan, Marwa Abdul Muhsien; Agool, Ibrahim Ramdan; Raoof, Lamyaa Mohammed

2014-04-01

126

Effect of Annealing on Slightly Oxidized Silicon Surface  

NASA Astrophysics Data System (ADS)

We investigated the effect of annealing on slightly oxidized silicon surfaces by using atomic force microscopy (AFM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The very thin oxide films (˜1 nm) were made by chemical treatment for three kinds of samples. One of them was p-type Si(100) wafer, the others were heavily phosphorus-doped Si(100) wafers made by ion implantation and low pressure chemical vapor deposition. These samples were annealed at low temperature (700°C˜900°C) in ultra high vacuum. AFM measurements showed that RMS roughness of all surfaces after annealing in UHV was several times as much as that of the surfaces right after chemical treatment. The morphology of every sample after oxide silicon desorbed by annealing revealed dot shape. And the morphology of p-type Si(100) after annealing at 730°C resembled that of heavily phosphorus-doped Si(100) made by ion implantation after annealing at 830°C. AES and XPS measurements showed that the difference of annealing temperature for these samples was due to the difference of their oxide thickness and the quality of their oxides.

Kakimoto, Masashi; Sano, Yuichi; Kamiura, Yoshitomo; Mizokawa, Yusuke

127

HOT ELECTRONS INJECTION INTO THE OXIDE OF A SILICON-ON-SAPPHIRE IGFET  

E-print Network

619 HOT ELECTRONS INJECTION INTO THE OXIDE OF A SILICON-ON-SAPPHIRE IGFET AT LOW OPERATING VOLTAGE injection from the electrical substrate of a silicon-on-sapphire IGFET into the gate insulator at low

Boyer, Edmond

128

Oxidation of silicon with a 5 eV O - beam  

NASA Astrophysics Data System (ADS)

A silicon wafer has been oxidized at room temperature in vacuum using a pure, ground-state beam of O- ions. The beam was of sufficiently low energy that no displacement damage or implantation was energetically possible. The resulting SiO2 films were analyzed with x-ray photoelectron spectroscopy. A logarithmic dependence of oxide thickness on dose was observed, with an extrapolated oxidation efficiency of unity for the clean silicon surface. A distinct initial oxidation phase was observed, with an anomalously high level of silicon suboxides. In addition, the valence-band offset between the silicon and the oxide was unusually small, suggesting a large interfacial dipole.

Hecht, M. H.; Orient, O. J.; Chutjian, A.; Vasquez, R. P.

1989-01-01

129

Enhanced photoelectrochemical water oxidation on bismuth vanadate by electrodeposition of amorphous titanium dioxide.  

PubMed

n-BiVO4 is a promising semiconductor material for photoelectrochemical water oxidation. Although most thin-film syntheses yield discontinuous BiVO4 layers, back reduction of photo-oxidized products on the conductive substrate has never been considered as a possible energy loss mechanism in the material. We report that a 15 s electrodeposition of amorphous TiO2 (a-TiO2) on W:BiVO4/F:SnO2 blocks this undesired back reduction and dramatically improves the photoelectrochemical performance of the electrode. Water oxidation photocurrent increases by up to 5.5 times, and its onset potential shifts negatively by ?500 mV. In addition to blocking solution-mediated recombination at the substrate, the a-TiO2 film-which is found to lack any photocatalytic activity in itself-is hypothesized to react with surface defects and deactivate them toward surface recombination. The proposed treatment is simple and effective, and it may easily be extended to a wide variety of thin-film photoelectrodes. PMID:25243345

Eisenberg, David; Ahn, Hyun S; Bard, Allen J

2014-10-01

130

Electric current generation in photorefractive bismuth silicon oxide without application of external electric field  

NASA Astrophysics Data System (ADS)

A holographic radial diffraction grating (HRDG) is an efficient optical element for splitting single laser beam on three 0, -1st, and +1st- diffraction order beams. The rotation of the grating at certain velocity allows a window for quality control over the frequency detuning between -1st, and +1st diffracted beams. The running interference fringes produced by the beams and projected on photorefractive crystal induce running holographic gratings in the crystal. This simple configuration is an effective tool for the study of such phenomena as space charge waves [1], domains motion [2], and electric current generation [3]. Specifics of photorefractive mechanism in cubic photorefractive crystals (BSO, BTO) normally require a use of external electric field to produce reasonable degree of refractive index modulation to observe associated with it phenomena. In this work we provide a direct experimental observation of the electric current generated in photorefractive BSO using running grating technique without an applied electric field. Moving interference fringes modulate a photoconductivity and an electric field in photorefractive crystal thus creating the photo electro-motive force (emf) and the current. The magnitude of the current varies between 1 and 10 nA depending on the rotation speed of HRDG. The peculiarities of the current behavior include a backward current flow, and current oscillations. The holographic current generated through this technique can find applications in non-destructive testing for ultra-sensitive vibrometry, materials characterization, and for motion sensors. References [1] S.F. Lyuksyutov, P. Buchhave, and M.V. Vasnetsov, Physical Review Letters, 79, No.1, 67-70 (1997) [2] P. Buchhave, S. Lyuksyutov, M. Vasnetsov, and C. Heyde, Journal Optical Society of America B, 13, No.11 2595-2602 (1996) [3] M. Vasnetsov, P. Buchhave, and S. Lyuksyutov Optics Communications, 137, 181-191 (1997)

Buchhave, Preben; Kukhtarev, Nickolai; Kukhtareva, Tatiana; Edwards, Matthew E.; Reagan, Michael A.; Lyuksyutov, Sergei F.

2003-10-01

131

Charge-trapping properties of gate oxide grown on nitrogen-implanted silicon substrate  

E-print Network

with no nitrogen implant, that followed the same processing cycle as that of the nitrogen-implanted oxide. HighCharge-trapping properties of gate oxide grown on nitrogen-implanted silicon substrate D. Misraa oxide grown on a nitrogen-implanted silicon substrate were investigated using high-field Fowler

Misra, Durgamadhab "Durga"

132

Method for removing oxide contamination from silicon carbide powders  

DOEpatents

The described invention is directed to a method for removing oxide contamination in the form of oxygen-containing compounds such as SiO/sub 2/ and B/sub 2/O/sub 3/ from a charge of finely divided silicon carbide. The silicon carbide charge is contacted with a stream of hydrogen fluoride mixed with an inert gas carrier such as argon at a temperature in the range of about 200/sup 0/ to 650/sup 0/C. The oxides in the charge react with the heated hydrogen fluoride to form volatile gaseous fluorides such as SiF/sub 4/ and BF/sub 3/ which pass through the charge along with unreacted hydrogen fluoride and the carrier gas. Any residual gaseous reaction products and hydrogen fluoride remaining in the charge are removed by contacting the charge with the stream of inert gas which also cools the powder to room temperature. The removal of the oxygen contamination by practicing the present method provides silicon carbide powders with desirable pressing and sintering characteristics. 1 tab.

Brynestad, J.; Bamberger, C.E.

1984-08-01

133

Transparent conducting oxides (TCO's) for amorphous silicon solar cells  

NASA Astrophysics Data System (ADS)

The stability of various textured tin oxide and zinc oxide transparent conductors was evaluated against annealing in air, in vacuum or exposed to hydrogen plasma. Only fluorine-doped zinc oxide deposited by atmospheric pressure chemical vapor deposition (APCVD) had stable electrical and optical properties under all conditions. Thin layers of ZnO or TiO2 greatly improved the plasma resistance of SnO2. A new TCO material, niobium-doped titanium dioxide (TiO2:Nb) was able to withstand hydrogen plasmas with only slight increases in its optical absorption and conductivity. Composite TCO's consisting of glass/SnO2:F/TiO2:Nb were shown to provide good electrical contact to amorphous silicon solar cells.

Hegedus, Steven; Liang, Haifan; Gordon, Roy G.

1996-01-01

134

Anodic oxidation during MEMS processing of silicon and polysilicon: native oxides can be thicker than you think  

Microsoft Academic Search

The thickness and surface roughness of the native oxide on undoped and P-doped single crystal silicon and polycrystalline silicon (polysilicon) were measured after exposure to aqueous hydrofluoric acid (HF) in the presence of localized metallization of sputtered Au or Pd. Both P-doping and the presence of metallization led to an increase in the thickness of the native surface oxide and

Harold Kahn; Chris Deeb; Ioannis Chasiotis; Arthur H. Heuer

2005-01-01

135

Thermal oxidation of 3C silicon carbide single-crystal layers on silicon  

NASA Technical Reports Server (NTRS)

Thermal oxidation of thick single-crystal 3C SiC layers on silicon substrates was studied. The oxidations were conducted in a wet O2 atmosphere at temperatures from 1000 to 1250 C for times from 0.1 to 50 h. Ellipsometry was used to determine the thickness and index of refraction of the oxide films. Auger analysis showed them to be homogeneous with near stoichiometric composition. The oxide growth followed a linear parabolic relationship with time. Activation energy of the parabolic rate constant was found to be 50 kcal/mole, while the linear rate constant was 74 kcal/mole. The latter value corresponds approximately to the energy required to break a Si-C bond. Electrical measurements show an effective density of 4-6 x 10 to the 11th per sq cm for fixed oxide charges at the oxide-carbide interface, and the dielectric strength of the oxide film is aproximately 6 x 10 to the 6th V/cm.

Fung, C. D.; Kopanski, J. J.

1984-01-01

136

Noncontact Measurement of Sodium Ions in Silicon Oxide  

NASA Astrophysics Data System (ADS)

In this study, we discuss the evaluation of sodium ions in silicon oxides (SiO2) by noncontact capacitance-voltage measurement and ultraviolet (UV) irradiation. The oxide charge (Nox) of sodium-contaminated wafer decreases with UV irradiation. The dependence of Nox on the UV wavelength indicates that the electrons excited by UV light are injected from the silicon into the oxide conduction band and subsequently trapped in the SiO2. The injected electrons are trapped only in the vicinity of the SiO2 surface, resulting in the neutralization of the sodium ions located near the surface when a wafer is irradiated by UV light at room temperature. The UV irradiation at elevated temperature, however, enables the sodium ions to move from the Si/SiO2 interface toward the SiO2 surface and to be completely neutralized. The change in Nox with UV irradiation shows good agreement with the sodium ion concentration determined by the bias temperature stress method.

Kohno, Motohiro; Kitajima, Toshikazu; Okada, Hiroshi; Hirae, Sadao; Sakai, Takamasa

2002-04-01

137

Characterization of HT-9 Ferritic-Martensitic Steels Oxidized in Lead Bismuth Eutectic , A. T. Motta1  

E-print Network

to neutrons, lead bismuth eutectic (LBE) is an considered an ideal candidate for cooling these fast reactors 87545 Contact email: jmk598@psu.edu INTRODUCTION The Lead-Cooled Fast Reactor (LFR) design is one point, low chemical reactivity, high boiling point, good gamma shielding, and high transparency

Motta, Arthur T.

138

Origin of complex impact craters on native oxide coated silicon surfaces  

SciTech Connect

Crater structures induced by impact of keV-energy Ar{sub n}{sup +} cluster ions on silicon surfaces are measured with atomic force microscopy. Complex crater structures consisting of a central hillock and outer rim are observed more often on targets covered with a native silicon oxide layer than on targets without the oxide layer. To explain the formation of these complex crater structures, classical molecular dynamics simulations of Ar cluster impacts on oxide coated silicon surfaces, as well as on bulk amorphous silica, amorphous Si, and crystalline Si substrates, are carried out. The diameter of the simulated hillock structures in the silicon oxide layer is in agreement with the experimental results, but the simulations cannot directly explain the height of hillocks and the outer rim structures when the oxide coated silicon substrate is free of defects. However, in simulations of 5 keV/atom Ar{sub 12} cluster impacts, transient displacements of the amorphous silicon or silicon oxide substrate surfaces are induced in an approximately 50 nm wide area surrounding the impact point. In silicon oxide, the transient displacements induce small topographical changes on the surface in the vicinity of the central hillock. The comparison of cluster stopping mechanisms in the various silicon oxide and silicon structures shows that the largest lateral momentum is induced in the silicon oxide layer during the impact; thus, the transient displacements on the surface are stronger than in the other substrates. This can be a reason for the higher frequency of occurrence of the complex craters on oxide coated silicon.

Samela, Juha; Nordlund, Kai; Popok, Vladimir N.; Campbell, Eleanor E. B. [Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 Espoo (Finland); Department of Physics, Gothenburg University, 41296 Gothenburg (Sweden); Department of Physics, Gothenburg University, 41296 Gothenburg, Sweden and School of Chemistry, Edinburgh University, West Mains Road, Edinburgh EH9 3JJ, Scotland (United Kingdom)

2008-02-15

139

Understanding the role of silicon oxide shell in oxide-assisted SiNWs growth  

SciTech Connect

The role of silicon oxide shell in oxide-assisted SiNWs growth is studied by performing ab initio molecular dynamics simulations on the structural and dynamical properties of the interface between crystalline Si(111) surface and disorder SiO thin film. Si atoms in the SiO film tends to aggregate into the vicinity of the Si(111)/SiO interface. In addition, the diffusion of Si atoms at the interface is anisotropic - the diffusion along the interface is several times faster than that perpendicular to the interface. The segregation and anisotropic diffusion of Si atoms at the Si(111)/SiO interface shed interesting light into the mechanism of oxide-assisted silicon nanowire growth.

Wu, Shunqing [Ames Laboratory; Wang, Cai-Zhuang Z [Ames Laboratory; Zhu, Z Z [Xiamen University; Ho, Kai-Ming [Ames Laboratory

2014-12-01

140

Correlation of gate oxide integrity with crystalline defects in silicon  

NASA Astrophysics Data System (ADS)

This thesis is concerned with gate oxide integrity degradation due to crystal silicon grown-in and process-induced defects. Many tools have been invented to detect these defects, however, clear explanations for the gate oxide integrity degradation mechanism of these defects are still missing. One of the major difficulties of studying grown-in micro defects is their low density, below 10sp6\\ cmsp{-3}. Therefore, precise defect localization techniques are needed. To solve this problem, we focused on the metal oxide semiconductor (MOS)/electron beam induced current (EBIC) technique which is the only method to achieve a direct one-to-one correlation of defects and degradation source. Finally, we have developed a novel failure analysis procedure using scanning electron microscopy (SEM)/EBIC image identification of individual breakdown sites under sub-nano ampere stress currents, followed by focused ion beam (FIB) marking for oxide defect localization using high resolution scanning electron microscopy (HRSEM), and transmission electron microscopy (TEM). By this technique, the damage strength associate with breakdown was evaluated with changing the breakdown stress current from micro to nano ampere for Poly-Si gate MOS capacitors which are fabricated on the boron doped substrate. The breakdown induced damage is strongly reduced below nano ampere. Under such a small damage regime, we observed the origin of the medium electric field breakdown for as-grown CZ wafers. It was an octahedral void, the same as that delineated by others using copper decoration method. To study for the failure mechanism of both grown-in and process-induced defects, we focused on the impact of Al or Poly-Si gate electrodes and oxide thickness on gate oxide integrity. Recent studies of the MOS capacitor gate oxide integrity B-mode failure ratios indicate a peak for an oxide thickness of either {˜}40 nm or from 70 to 100 nm. In present research, however, more precise analysis using commutative failure plots revealed that these peaks are artificial. It can be changed by the occurrence of self-healing. We found that grown-in defects have different degradation effect to Al and Poly-Si gate films, whereas oxygen precipitates have not. Finally we proposed the degradation model of grown-in voids and oxygen precipitates. Other fundamental topics are oxide defect annihilation and generation phenomena due to high temperature heat treatments. We have investigated B- and C-mode oxide defects and flow pattern (FP) and laser scattering tomography (LST) defects as a function of depth for hydrogen, argon, and dry oxygen ambient. The gate oxide strength depth profile of wafers after dry oxidation at 1200sp° C was essentially homogeneous; whereas, for hydrogen and argon annealing ambient a variety of breakdown strength distributions were found. These oxide defect failure profiles were correlated with FPD and LSTD. The EBIC technique was used to delineate both B- and C-mode oxide failure sites. Subsequent one-to-one TEM observations of these EBIC defects marked by a focused ion beam revealed the origin of the B-mode oxide defect to be a residual void. Both qualitative and quantitative models based on point defect injection from the surface and the silicon bulk is proposed to explain the unique oxide defect distributions after hydrogen or argon annealing. In the summary, practical recommendation of suitable defect engineering options for the next ULSI era. is discussed.

Tamatsuka, Masaro

1997-12-01

141

A scalable silicon microreactor for preferential CO oxidation: performance comparison with a tubular  

E-print Network

A scalable silicon microreactor for preferential CO oxidation: performance comparison technology which does not scale down in a feasible manner. A microchannel reactor was fabricated in silicon obtained from a conventional packed-bed microreactor. The silicon microreactor performs very well, while

Gulari, Erdogan

142

Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation  

SciTech Connect

We report the observation of enhanced oxidation on silicon and porous silicon samples exposed in air ambient to high-dose-rate 10 keV x-ray radiation at room temperature. The evolution of the radiation-induced oxide growth is monitored by ellipsometry and interferometric reflectance spectroscopy. Fourier transform infrared (FTIR) spectroscopy shows the emergence of Si-O-Si stretching modes and corresponding suppression of SiH{sub x} and Si-Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide thickness and Si-H surface species. The enhanced oxidation mechanism is attributed to photoinduced oxidation processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation of more reactive oxygen species.

Ryckman, Judson D.; Reed, Robert A.; Weller, Robert A.; Fleetwood, D. M.; Weiss, S. M. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2010-12-01

143

Effect of capping silicon nitride layer and nitrided gate oxide on hump of transistors  

Microsoft Academic Search

In this letter, we investigate the effect of capping silicon nitride and nitrided gate oxide on the hump in the sub-threshold slope of various transistors. Silicon wafers having both high- and low-voltage transistors are fabricated. The thin gate oxide is grown by nitric oxidation, while two step process of dry oxidation and low-pressure chemical vapor deposition (LPCVD) is used for

Won K. Park; Jung H. Lee; Geun Lim

2004-01-01

144

Oxidation behavior of silicon nitride sintered with Lu 2 O 3 additive  

Microsoft Academic Search

Kyocera SN282 silicon nitride ceramics sintered with 5.35 wt% Lu2O3 were oxidized in dry oxygen at 930–1,200 °C. Oxidation of SN282 follows a parabolic rate law. SN282 exhibits significantly lower parabolic rate constants and better oxide morphological stability than silicon nitride containing other sintering additives under similar conditions. The activation energy for oxidation of SN282 is 107 ± 5 kJ\\/mol K, suggesting inward diffusion of molecular

Madeleine K. Jordache; Henry Du

2006-01-01

145

Selective Growth of ?-Sexithiophene by Using Silicon Oxides Patterns  

PubMed Central

A process for fabricating ordered organic films on large area is presented. The process allows growing sexithiophene ultra-thin films at precise locations on patterned Si/SiOx substrates by driving the orientation of growth. This process combines the parallel local anodic oxidation of Si/SiOx substrates with the selective arrangement of molecular ultra-thin film. The former is used to fabricate silicon oxide arrays of parallel lines of 400 nm in width over an area of 1 cm2. Selective growth arises from the interplay between kinetic growth parameters and preferential interactions with the patterned surface. The result is an ultra-thin film of organic molecules that is conformal to the features of the fabricated motives. PMID:22016622

Albonetti, Cristiano; Barbalinardo, Marianna; Milita, Silvia; Cavallini, Massimiliano; Liscio, Fabiola; Moulin, Jean-François; Biscarini, Fabio

2011-01-01

146

Variable conductivity of nanocomposite nickel oxide/porous silicon  

NASA Astrophysics Data System (ADS)

Continuous-state variable conductivity of nickel oxide/porous silicon nanocomposite thin films indicative of memristance is reported and a mathematical model for the observed behavior is proposed. The variable conductivity phenomena observed are shown to depend on the composition of the films. A generalized composite material conductivity model that explains the time-varying, field-dependent conductivity modulation is developed based on ionic defect migration in the metal oxide nanocrystallites. The model shows excellent agreement with experimental data and allows for estimation of ionic defect mobilities. Multicycle nonvolatility in the devices is shown to be on the order of 1000 s. The tunable conductivity of the nanocomposite is potentially useful in the fabrication of large-scale or high-power analog circuit elements such as memristors, and provides insights into ionic defect migration properties in nanocomposite materials.

Mares, Jeremy W.; Fain, Joshua S.; Weiss, Sharon M.

2013-08-01

147

Translocation of double-strand DNA through a silicon oxide nanopore A. J. Storm,1  

E-print Network

Translocation of double-strand DNA through a silicon oxide nanopore A. J. Storm,1 J. H. Chen,1,2 H experiments using silicon oxide nanopores with a diameter of about 10 nm. By monitoring the conductance and estimate the folding position. As a proof-of-principle experiment, we show that a nanopore can be used

Dekker, Cees

148

Properties of aluminum oxide and aluminum oxide alloys and their interfaces with silicon and silicon dioxide  

Microsoft Academic Search

A remote plasma enhanced chemical vapor deposition method, RPECVD, was utilized to deposit thin films of aluminum oxide, tantalum oxide, tantalum aluminates, and hafnium aluminates. These films were analyzed using auger electron spectroscopy, AES, Fourier transform infrared spectroscopy, FTIR, X-ray diffraction, XRD, nuclear resonance profiling, NRP, capacitance versus voltage, C-V, and current versus voltage, J-V. FTIR indicated the alloys were

Robert Shawn Johnson

2002-01-01

149

Optical properties of bismuth-doped silica fibres in the temperature range 300 — 1500 K  

NASA Astrophysics Data System (ADS)

The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi3+ profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect.

Dvoretskii, D. A.; Bufetov, Igor'A.; Vel'miskin, V. V.; Zlenko, Alexander S.; Khopin, V. F.; Semjonov, S. L.; Guryanov, Aleksei N.; Denisov, L. K.; Dianov, Evgenii M.

2012-09-01

150

Atomic absorption spectroscopic measurements of silicon atom concentrations in electron cyclotron resonance silicon oxide deposition plasmas  

NASA Astrophysics Data System (ADS)

The silicon atom densities in both silane/oxygen and tetraethoxysilane (TEOS)/oxygen electron cyclotron resonance (ECR) plasmas were measured as functions of microwave power, pressure, and gas flow rates. An atomic absorption spectrometer with a Si hollow-cathode lamp was constructed for these measurements. Silicon atom densities in silane/oxygen ECR discharges increase with rising plasma density, and a strong correlation was found between the Si atom gas-phase abundance and the silicon oxide film deposition rate. The measured Si concentrations [(1-7)×1010 cm-3] were high enough to account for a significant part of the film growth in the silane based chemistry. In TEOS/O2 discharges Si atom concentrations were lower by an order of magnitude, so Si is probably not a major contributor to the growth rate in that case. The internal temperature of Si atoms was found to vary from 380 to 720 K with increasing microwave power (200-650 W).

Augustyniak, Edward; Chew, Kok Heng; Shohet, J. Leon; Woods, R. Claude

1999-01-01

151

Structural Evolution of Silicon Oxide Nanowires via Head-Growth Solid-Liquid-Solid Process  

NASA Astrophysics Data System (ADS)

In this paper, we propose a growth mechanism for silicon oxide nanowires (SiONWs) as a unique solid-liquid-solid process. SiONWs were synthesized in a furnace at 1000 °C and cooled at a high rate. Nickel and gold were introduced as catalysts to dissolve and precipitate the silicon oxide originally prepared by wet oxidation. The ratio of nickel to gold determined the precipitation rate and different “octopus-like” structures were formed. At a specific cooling rate, composition and amount of a catalyst, aligned silicon oxide nanowires with unattached ends were obtained.

Hsu, Cheng-Hang; Chan, Shih-Yu; Chen, Chia-Fu

2007-11-01

152

Single-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser  

E-print Network

Single-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser K. K and demonstrate a stable single-longitudinal-mode lanthanum-codoped bismuth oxide- based erbium doped fiber ring

Wai, Ping-kong Alexander

153

Atomistic modeling of bending properties of oxidized silicon nanowires  

SciTech Connect

In this work, we have modeled a three point bending test of monocrystalline Si nanowires using molecular dynamics simulations in order to investigate their elastic properties. Tested nanowires were about 30?nm in length and had diameters from 5 to 9?nm. To study the influence of a native oxide layer, nanowires were covered with a 1?nm thick silica layer. The bending force was applied by a carbon diamond half-sphere with a 5?nm diameter. The Si-O parametrization for the Tersoff potential was used to describe atomic interactions between Si and O atoms. In order to remove the indentation effect of the diamond half-sphere and to obtain a pure bending behavior, we have also performed a set of simulations with fixed bottoms of the nanowires. Our results show that the oxide layer reduces the nanowire stiffness when compared with a pure Si nanowire with the same number of silicon atoms—in spite of the fact that the oxidized nanowires had larger diameters.

Ilinov, Andrey, E-mail: andrey.ilinov@helsinki.fi; Kuronen, Antti [Department of Physics, University of Helsinki, P.O. Box 43, FIN-00014 Helsinki (Finland)

2014-03-14

154

Atomic layer deposition of bismuth oxide using Bi(OCMe{sub 2}{sup i}Pr){sub 3} and H{sub 2}O  

SciTech Connect

Bismuth oxide thin films were deposited by atomic layer deposition using Bi(OCMe{sub 2}{sup i}Pr){sub 3} and H{sub 2}O at deposition temperatures between 90 and 270?°C on Si{sub 3}N{sub 4}, TaN, and TiN substrates. Films were analyzed using spectroscopic ellipsometry, x-ray diffraction, x-ray reflectivity, high-resolution transmission electron microscopy, and Rutherford backscattering spectrometry. Bi{sub 2}O{sub 3} films deposited at 150?°C have a linear growth per cycle of 0.039?nm/cycle, density of 8.3?g/cm{sup 3}, band gap of approximately 2.9?eV, low carbon content, and show the ? phase structure with a (201) preferred crystal orientation. Deposition temperatures above 210?°C and postdeposition anneals caused uneven volumetric expansion, resulting in a decrease in film density, increased interfacial roughness, and degraded optical properties.

Austin, Dustin Z., E-mail: austind@eecs.oregonstate.edu; Conley, John F., E-mail: jconley@eecs.oregonstate.edu [Department of Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon 97331 (United States); Allman, Derryl; Price, David; Hose, Sallie [ON Semiconductor, Technology Development, Gresham, Oregon 97030 (United States); Saly, Mark [SAFC Hitech, Haverhill, Massachusetts 01832 (United States)

2014-01-15

155

High-temperature oxidation behavior of reaction-formed silicon carbide ceramics  

NASA Technical Reports Server (NTRS)

The oxidation behavior of reaction-formed silicon carbide (RFSC) ceramics was investigated in the temperature range of 1100 to 1400 C. The oxidation weight change was recorded by TGA; the oxidized materials were examined by light and electron microscopy, and the oxidation product by x-ray diffraction analysis (XRD). The materials exhibited initial weight loss, followed by passive weight gain (with enhanced parabolic rates, k(sub p)), and ending with a negative (logarithmic) deviation from the parabolic law. The weight loss arose from the oxidation of residual carbon, and the enhanced k(sub p) values from internal oxidation and the oxidation of residual silicon, while the logarithmic kinetics is thought to have resulted from crystallization of the oxide. The presence of a small amount of MoSi, in the RFSC material caused a further increase in the oxidation rate. The only solid oxidation product for all temperatures studied was silica.

Ogbuji, Linus U. J. T.; Singh, M.

1995-01-01

156

Optimal size regime for oxidation-resistant silicon quantum dots.  

PubMed

First-principles computations have been carried out to predict that appropriately terminated silicon quantum dots with diameters in the range of 1.2-2 nm will offer a superb resistance to oxidation. This is because surface treatments can produce dangling bond defect densities sufficiently low that dots of this size are unlikely to have any defect at all. On the other hand, these dots are large enough that the severe angles between facets do not expose bonds that are vulnerable to subsequent oxygen attack. The absence of both surface defects and geometry-related vulnerabilities allows even very short passivating ligands to generate an effective barrier, an important consideration for charge and exciton transport within quantum dot assemblies. Our computations, which employ many-body perturbation theory using Green functions, also indicate that dots within this size regime have optical and electronic properties that are robust to small amounts of inadvertent oxidation, and that any such oxygen incorporation is essentially frozen in place. PMID:23061893

Li, Huashan; Lusk, Mark T; Collins, Reuben T; Wu, Zhigang

2012-11-27

157

Ion irradiation of the native oxide/silicon surface increases the thermal boundary conductance across aluminum/silicon interfaces  

NASA Astrophysics Data System (ADS)

The thermal boundary conductance across solid-solid interfaces can be affected by the physical properties of the solid boundary. Atomic composition, disorder, and bonding between materials can result in large deviations in the phonon scattering mechanisms contributing to thermal boundary conductance. Theoretical and computational studies have suggested that the mixing of atoms around an interface can lead to an increase in thermal boundary conductance by creating a region with an average vibrational spectra of the two materials forming the interface. In this paper, we experimentally demonstrate that ion irradiation and subsequent modification of atoms at solid surfaces can increase the thermal boundary conductance across solid interfaces due to a change in the acoustic impedance of the surface. We measure the thermal boundary conductance between thin aluminum films and silicon substrates with native silicon dioxide layers that have been subjected to proton irradiation and post-irradiation surface cleaning procedures. The thermal boundary conductance across the Al/native oxide/Si interfacial region increases with an increase in proton dose. Supported with statistical simulations, we hypothesize that ion beam mixing of the native oxide and silicon substrate within ˜2.2nm of the silicon surface results in the observed increase in thermal boundary conductance. This ion mixing leads to the spatial gradation of the silicon native oxide into the silicon substrate, which alters the acoustic impedance and vibrational characteristics at the interface of the aluminum film and native oxide/silicon substrate. We confirm this assertion with picosecond acoustic analyses. Our results demonstrate that under specific conditions, a "more disordered and defected" interfacial region can have a lower resistance than a more "perfect" interface.

Gorham, Caroline S.; Hattar, Khalid; Cheaito, Ramez; Duda, John C.; Gaskins, John T.; Beechem, Thomas E.; Ihlefeld, Jon F.; Biedermann, Laura B.; Piekos, Edward S.; Medlin, Douglas L.; Hopkins, Patrick E.

2014-07-01

158

Oxidation of Germanium and Silicon surfaces (100): a comparative study through DFT methodology  

NASA Astrophysics Data System (ADS)

Density Functional Theory calculations are used to map out the preferential oxygen molecule adsorption sites and oxygen atom incorporation on germanium (100) surface. A comparison with primary oxidation mechanisms encountered in pure silicon and silicon germanium (100) surfaces is presented here. This study highlights opposite substrates behaviors facing oxygen molecule adsorption: 1/ surface germanium atoms move from their crystalline positions to adapt to the approaching oxygen molecule resulting in adsorbed peroxide bridge configuration, whereas oxygen molecule is fully dissociated in strand configuration on a silicon surface 2/ oxygen atoms tend to avoid each other on germanium surface whereas oxide nucleus can be observed on silicon surface even at the early steps of the oxidation process. Results show that germanium surface appears to be less reactive than the silicon substrate towards molecular oxygen species.

Mastail, C.; Bourennane, I.; Estève, A.; Landa, G.; Djafari Rouhani, M.; Richard, N.; Hémeryck, A.

2012-12-01

159

Microstructure, toughness and flexural strength of self-reinforced silicon nitride ceramics doped with yttrium oxide and ytterbium oxide.  

PubMed

Self-reinforced silicon nitride ceramics with additions of either yttrium oxide or ytterbium oxide have been investigated at room temperature after various processing heat treatments. Devitrification of the intergranular phase in these materials is very sensitive to the heat treatment used during processing and does not necessarily improve their strength and toughness. Hot-pressed ceramics without a subsequent devitrification heat treatment were the strongest. The ytterbium oxide-doped silicon nitride ceramics were consistently tougher, but less strong, than the yttrium oxide-doped silicon nitride ceramics. In all the ceramics examined, the fracture toughness showed evidence for R-curve behaviour. This was most significant in pressureless sintered ytterbium oxide-doped silicon nitride ceramics. A number of toughening mechanisms, including crack deflection, bridging, and fibre-like grain pull-out, were observed during microstructural analysis of the ceramics. In common with other silicon nitride-based ceramics, thin amorphous films were found at the grain boundaries in each of the ceramics examined. Arrays of dislocations left in the elongated silicon nitride grains after processing were found to belong to the {101;0}<0001> primary slip system. PMID:11207926

Zheng, Y. S.; Knowles, K. M.; Vieira, J. M.; Lopes, A. B.; Oliveira, F. J.

2001-02-01

160

Modeling and experimental validation of sharpening mechanism based on thermal oxidation for fabrication of ultra-sharp silicon nanotips  

Microsoft Academic Search

This paper aims at modeling the thermal oxidation of silicon pillars leading to the formation of very sharp silicon tips. The model is used to determine optimum process parameters with respect to the initial shape of the silicon pillars and the geometry of the desired tip. The modeling concept is to extend a previous approach, which predicts the oxidation mechanism

Vincent Agache; Roger Ringot; Patrice Bigotte; Vincent Senez; Bernard Legrand; Lionel Buchaillot; Dominique Collard

2005-01-01

161

Fabrication of amorphous silicon nanoribbons by atomic force microscope tip induced local oxidation for thin film device applications  

E-print Network

1 Fabrication of amorphous silicon nanoribbons by atomic force microscope tip induced local We demonstrate the feasibility of induced local oxidation of amorphous silicon by atomic force. A thin amorphous silicon layer deposited on a glass substrate is locally oxidized following narrow

Paris-Sud XI, Université de

162

Synchrotron x-ray reflectivity study of oxidation/passivation of copper and silicon.  

SciTech Connect

Synchrotron x-ray-scattering technique studies of copper and silicon electrochemical interfaces are reported. These two examples illustrate the application of synchrotron x-ray techniques for oxidation, passivation, and dissolution of metals and semiconductors.

Chu, Y.; Nagy, Z.; Parkhutik, V.; You, H.

1999-07-21

163

Modelling and engineering of stress based controlled oxidation effects for silicon nanostructure patterning  

NASA Astrophysics Data System (ADS)

Silicon nanostructure patterning with tight geometry control is an important challenge at the bottom level. In that context, stress based controlled oxidation appears to be an efficient tool for precise nanofabrication. Here, we investigate the stress-retarded oxidation phenomenon in various silicon nanostructures (nanobeams, nanorings and nanowires) at both the experimental and the theoretical levels. Different silicon nanostructures have been fabricated by a top-down approach. Complex dependence of the stress build-up on the nano-object’s dimension, shape and size has been demonstrated experimentally and physically explained by modelling. For the oxidation of a two-dimensional nanostructure (nanobeam), relative independence to size effects has been observed. On the other hand, radial stress increase with geometry downscaling of a one-dimensional nanostructure (nanowire) has been carefully emphasized. The study of shape engineering by retarded oxidation effects for vertical silicon nanowires is finally discussed.

Han, Xiang-Lei; Larrieu, Guilhem; Krzeminski, Christophe

2013-12-01

164

Method for forming indium oxide/n-silicon heterojunction solar cells  

DOEpatents

A high photo-conversion efficiency indium oxide/n-silicon heterojunction solar cell is spray deposited from a solution containing indium trichloride. The solar cell exhibits an Air Mass One solar conversion efficiency in excess of about 10%.

Feng, Tom (Morris Plains, NJ); Ghosh, Amal K. (New Providence, NJ)

1984-03-13

165

Correlation between density and oxidation temperature for pyrolytic-gas passivated ultrathin silicon oxide films  

NASA Astrophysics Data System (ADS)

Pyrolytic-gas passivation (PGP) with a small amount nitrogen gas enhances the breakdown reliability of silicon oxide gate films. To clarify the reliability retention of the PGP-grown films oxidized at low temperature, densities (?ox's) of the 3.5-6.5-nm-thick PGP-grown films on Si(100) oxidized at 700-900 °C were investigated. Since ?ox's correlate well with the reliability and are useful as an index of the intrinsic structural characteristics of the films. Moreover, changes in ?ox and nitrogen content corresponding to oxidation temperature are similar to those in breakdown reliability and interface state density (Dit), respectively. In addition, ?ox's of the 700 °C-grown PGP films do not deteriorate as much when compared with those of the films grown by normal ultradry oxidation at 800 °C and their Dit's are less than about 6×1010/eV cm2. This suggests that PGP probably improves the reliability by generating the higher-?ox microscopic structure with few Si dangling bonds and effective passivation. .

Yamada, Hiroshi

2004-01-01

166

Electrical conduction and dielectric breakdown in aluminum oxide insulators on silicon  

Microsoft Academic Search

Leakage currents and dielectric breakdown were studied in MIS capacitors of metal-aluminum oxide-silicon. The aluminum oxide was produced by thermally oxidizing AlN at 800-1160°C under dry O2 conditions. The AlN films were deposited by RF magnetron sputtering on p-type Si (100) substrates. Thermal oxidation produced Al 2O3 with a thickness and structure that depended on the process time and temperature.

James Kolodzey; Enam Ahmed Chowdhury; Thomas N. Adam; Guohua Qui; I. Rau; J. O. Olowolafe; J. S. Suehle; Yuan Chen

2000-01-01

167

The influence of natural and stimulated oxidation on luminescent properties of silicon-cellulose nanocomposites  

NASA Astrophysics Data System (ADS)

A composite has been developed on the basis of nanocrystalline cellulose and silicon nanoparticles, which exhibited more intense photoluminescence in the visible range of the spectrum than did nanoporous silicon. This may be related to the spatial separation of silicon nanoparticles and migration of excitation from their vicinity. The effect of temperature and gas-phase oxidation on the luminescent properties of the material indicates a high stability of the luminescent properties of the composite. Investigation of the charging effect of the nanocomposite allows silicon nanoparticles to be considered as centers of accumulation of the bulk electricity charge.

Pikulev, V. B.; Loginova, S. V.; Gurtov, V. A.

2012-08-01

168

Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process  

DOEpatents

A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

McKee, Rodney A. (Kingston, TN); Walker, Frederick J. (Oak Ridge, TN)

1993-01-01

169

Ethylene oxide-block-butylene oxide copolymer uptake by silicone hydrogel contact lens materials  

NASA Astrophysics Data System (ADS)

Four major types of silicone hydrogel contact lens material have been investigated following treatments in aqueous solutions containing poly(ethylene oxide) and poly(butylenes oxide) block copolymer (EO-BO). The extent of lens surface modification by EO-BO and the degree of bulk uptake were studied using X-ray photoelectron spectroscopy (XPS) and ultra-performance liquid chromatography (UPLC), respectively. The experimental results suggest that different interaction models exist for the lenses, highlighting the influence of both surface and bulk composition, which greatly differs between the lenses examined. Specifically, lenses with hydrophilic surface treatments, i.e., PureVision® (balafilcon A) and O2OPTIX (lotrafilcon B), demonstrated strong evidence of preferential surface adsorption within the near-surface region. In comparison, surface adsorption on ACUVUE® Oasys® (senofilcon A) and Biofinity® (comfilcon A) was limited. As for bulk absorption, the amount of EO-BO uptake was the greatest for balafilcon A and comfilcon A, and least for lotrafilcon B. These findings confirm the presence of molecular concentration gradients within the silicone hydrogel lenses following exposure to EO-BO solutions, with the nature of such concentration gradients found to be lens-specific. Together, the results suggest opportunities for compositional modifications of lenses for improved performance via solution treatments containing surface-active agents.

Huo, Yuchen; Ketelson, Howard; Perry, Scott S.

2013-05-01

170

The adsorption of hyperbranched polymers on silicon oxide surfaces.  

PubMed

The electrostatic interaction between quarternised hyperbranched polymers (polyesteramides) and a silicon oxide (SiO2) surface has been studied via adsorption studies with quartz crystal microbalance instrument with dissipation (QCM-D). Frequency shift (Deltaf) results show that the increase in both pH and salt concentration positively affect the adsorbed amount of these polymers, calculated by Sauerbrey equation, on the QCM crystal. The adsorbed amount of HA1 (with lower molecular weight and higher charge density) was lower than that of HA2 (with higher molecular weight and lower charge density) in all experiments. It was also observed that there are no significant changes in the dissipation after adsorption of these polymers. This indicated that both hyperbranched polymers formed rigid adsorbed layers on the negative SiO2 surface. Additionally, the results were compared with adsorption of poly-DADMAC and the results showed that the hyperbranched polymers formed thicker and more rigid layers as compared with the poly-DADMAC. PMID:16820163

Ondaral, Sedat; Wågberg, Lars; Enarsson, Lars-Erik

2006-09-01

171

Silicon oxide permeation barrier coating of PET bottles and foils  

NASA Astrophysics Data System (ADS)

Modern packaging materials such as polyethylene terephthalate (PET) have displaced established materials in many areas of food and beverage packaging. Plastic packing materials offer are various advantages concerning production and handling. PET bottles for instance are non-breakable and lightweight compared to glass and metal containers. However, PET offers poor barrier properties against gas permeation. Therefore, the shelf live of packaged food is reduced. Permeation of gases can be reduced by depositing transparent plasma polymerized silicon oxide (SiOx) barrier coatings. A microwave (2.45 GHz) driven low pressure plasma reactor is developed based on a modified Plasmaline antenna to treat PET foils or bottles. To increase the barrier properties of the coatings furthermore a RF substrate bias (13.56 MHz) is applied. The composition of the coatings is analyzed by means of Fourier transform infrared (FTIR) spectroscopy regarding carbon and hydrogen content. Influence of gas phase composition and substrate bias on chemical composition of the coatings is discussed. A strong relation between barrier properties and film composition is found: good oxygen barriers are observed as carbon content is reduced and films become quartz-like. Regarding oxygen permeation a barrier improvement factor (BIF) of 70 is achieved.

Steves, Simon; Deilmann, Michael; Awakowicz, Peter

2009-10-01

172

Formation of ultrathin nitrided SiO{sub 2} oxides by direct nitrogen implantation into silicon  

SciTech Connect

A nitridation technique is proposed for ultrathin, SiO{sub 2} oxides in deep submicron CMOS technology, which involves direct implantation of molecular nitrogen (N{sub 2}) into the silicon substrate. N{sub 2} ions were implanted into silicon at different doses and energies, through a 150 {angstrom} thick screen oxide. In this study the effect of implanted N atoms on silicon oxidation, and SiO{sub 2} oxide nitridation process have been studied. Two groups of the N{sub 2}-implanted wafers were used: wafers from one group were annealed prior to the screen oxide removal, whereas wafers of the other group did not receive this anneal. It is shown that nitridation can be achieved both ways, allowing this technique to be easily integrated into a semiconductor IC fabrication process.

Soleimani, H.R.; Doyle, B.S.; Philipossian, A. [Digital Equipment Corp., Hudson, MA (United States). ULSI Operations Group

1995-08-01

173

Structural alloy with a protective coating containing silicon or silicon-oxide  

DOEpatents

An iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100.degree. C.

Natesan, Ken (Naperville, IL)

1994-01-01

174

Structural alloy with a protective coating containing silicon or silicon-oxide  

DOEpatents

This invention is comprised of an iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100{degrees}C.

Natesan, K.

1992-01-01

175

Characterization of polycrystalline silicon-oxide-nitride-oxide-silicon devices on a SiO2 or Si3N4 buffer layer  

NASA Astrophysics Data System (ADS)

Silicon-oxide-nitride-oxide-silicon (SONOS) memory devices were fabricated from polycrystalline silicon (poly-Si) using the solid phase crystallization (SPC) method for use in a low-power system-on-panel (SOP) display. In these poly-Si SONOS memories, oxide or nitride was used as a buffer layer. The electrical characteristics, such as the threshold voltage ( V T ), subthreshold slope ( SS) and transconductance ( g m ), were determined for each SONOS device. To interpret the characteristics of both poly-Si devices, x-ray diffraction (XRD) measurements and flicker noise analysis were conducted. The results show that the poly-Si SONOS on the oxide layer has better electrical, memory characteristics, such as turn-on speed and g m , program/erase, endurance and data retention than that on the nitride layer. From the XRD measurements, it is shown that the grain size of the poly-Si on the oxide layer is larger than that on the nitride layer. From the flicker noise analysis, the poly-Si device on oxide was shown to have less traps or defects in the channel layer than that on nitride.

Lee, Sang-Youl; Oh, Jae-Sub; Yang, Seung-Dong; Yun, Ho-Jin; Jeong, Kwang-Seok; Kim, Yu-Mi; Lee, Hi-Deok; Lee, Ga-Won

2013-10-01

176

The modulation on luminescence of Er3+-doped silicon-rich oxide films by the structure evolution of silicon nanoclusters  

PubMed Central

A series of silicon-rich oxide (SRO) and erbium-doped SRO (SROEr) films imbedded with structural tunable silicon nanoclusters (Si NCs) have been fabricated using sputtering followed by post-annealing. The coalescence of Si NCs is found in the films with large Si excess. The energy transfer rate between Si NCs and Er3+ is enhanced, but the luminescence efficiencies of both Si NCs and Er3+ are reduced by the coalescent microstructures. Optimization of the microstructures of Si NCs is performed, and the preferential optical performance for both Si NCs and Er3+ could be achieved when Si NCs were separated in microstructures. PMID:23331713

2013-01-01

177

Auger and ellipsometric study of phosphorus segregation in oxidized degenerate silicon  

Microsoft Academic Search

Phosphorus redistribution during thermal oxidation of degenerately doped silicon was investigated using Auger electron spectroscopy and ellipsometry. Concentration profiles were determined with a combination of chemical and sputter etching techniques. A substantial phosphorus pileup was observed in the oxide in a thin layer near the ellipsometrically determined Si-SiO2 interface. Calibrated against standards of known concentration, this layer was found to

N. J. Chou; Y. J. van der Meulen; R. Hammer; J. Cahill

1974-01-01

178

PHYSICAL REVIEW B 88, 075307 (2013) Variable conductivity of nanocomposite nickel oxide/porous silicon  

E-print Network

PHYSICAL REVIEW B 88, 075307 (2013) Variable conductivity of nanocomposite nickel oxide-state variable conductivity of nickel oxide/porous silicon nanocomposite thin films indicative of memristance is shown to be on the order of 1000 s. The tunable conductivity of the nanocomposite is potentially useful

Weiss, Sharon

179

Improvement of plasmonic enhancement of quantum dot emission via an intermediate silicon-aluminum oxide interface  

NASA Astrophysics Data System (ADS)

We studied the emission of quantum dots in the presence of plasmon-metal oxide substrates, which consist of arrays of metallic nanorods embedded in amorphous silicon coated with a nanometer-thin layer of aluminum oxide on the top. We showed that the combined effects of plasmons and the silicon-aluminum oxide interface can lead to significant enhancement of the quantum efficiency of quantum dots. Our results show that such an interface can significantly enhance plasmonic effects of the nanorods via quantum dot-induced exciton-plasmon coupling, leading to partial polarization of the quantum dots' emission.

Wing, Waylin J.; Sadeghi, Seyed M.; Campbell, Quinn

2015-01-01

180

Formation of titanium oxide films on the surface of porous silicon carbide  

NASA Astrophysics Data System (ADS)

The influence of rapid thermal annealing (RTA) on the properties of a titanium film on the surface of porous silicon carbide is considered. It is shown that an increase in the RTA temperature to 900°C stabilizes the phase composition of the forming titanium oxide over the film, which is identified as rutile. Due to the formation of titanium oxide nanoclusters under the action of RTA, an additional photoluminescence band arises near 2.5 eV. Based on Auger spectrometry data, a multilayer model to calculate the optical parameters of titanium oxide films covering porous silicon carbide is suggested.

Bacherikov, Yu. Yu.; Dmitruk, N. L.; Konakova, R. V.; Kondratenko, O. S.; Milenin, V. V.; Okhrimenko, O. B.; Kapitanchuk, L. M.; Svetlichnyi, A. M.; Moskovchenko, N. N.

2008-09-01

181

The complex interface chemistry of thin-film silicon/zinc oxide solar cell structures.  

PubMed

The interface between solid-phase crystallized phosphorous-doped polycrystalline silicon (poly-Si(n(+))) and aluminum-doped zinc oxide (ZnO:Al) was investigated using spatially resolved photoelectron emission microscopy. We find the accumulation of aluminum in the proximity of the interface. Based on a detailed photoemission line analysis, we also suggest the formation of an interface species. Silicon suboxide and/or dehydrated hemimorphite have been identified as likely candidates. For each scenario a detailed chemical reaction pathway is suggested. The chemical instability of the poly-Si(n(+))/ZnO:Al interface is explained by the fact that SiO2 is more stable than ZnO and/or that H2 is released from the initially deposited a-Si:H during the crystallization process. As a result, Zn (a deep acceptor in silicon) is "liberated" close to the silicon/zinc oxide interface presenting the inherent risk of forming deep defects in the silicon absorber. These could act as recombination centers and thus limit the performance of silicon/zinc oxide based solar cells. Based on this insight some recommendations with respect to solar cell design, material selection, and process parameters are given for further knowledge-based thin-film silicon device optimization. PMID:25363298

Gerlach, D; Wimmer, M; Wilks, R G; Félix, R; Kronast, F; Ruske, F; Bär, M

2014-12-21

182

Bismuth-doped tin oxide-coated carbon nanotube network: improved anode stability and efficiency for flow-through organic electrooxidation.  

PubMed

In this study, a binder-free, porous, and conductive 3D carbon-nanotube (CNT) network uniformly coated with bismuth-doped tin oxide (BTO) nanoparticles was prepared via a simple electrosorption-hydrothermal method and utilized for the electrooxidative filtration of organics. The BTO-CNT nanocomposite was characterized by scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectroscopy, linear sweep voltammetry, and Tafel analysis. The submonolayer BTO coating is composed of 3.9±1.5 nm diameter nanoparticles (NPs). The oxygen-evolution potential of the BTO-CNT nanocomposite was determined to be 1.71 V (vs Ag/AgCl), which is 440 mV higher than an uncoated CNT anode. Anodic stability, characterized by CNT oxidative corrosion to form dissolved species, indicated that the BTO-CNT incurred negligible corrosion up to Vanode=2.2 V, whereas the uncoated CNT was compromised at Vanode?1.4 V. The effect of metal oxide-nanoparticle coating on anodic performance was initially studied by oxalate oxidation followed by total organic carbon (TOC) and chemical oxygen demand (COD) analysis. The BTO-CNT displayed the best performance, with ?98% oxalate oxidation (1.2 s filter residence time) and current efficiencies in the range of 32 to >99%. The BTO-CNT anode energy consumption was 25.7 kW h kgCOD(-1) at ?93% TOC removal and 8.6 kW h kgCOD(-1) at ?50% TOC removal, comparable to state-of-the-art oxalate oxidation processes (22.5-81.7 kW h kgCOD(-1)). The improved reactivity, current efficiency, and energy consumption are attributed to the increased conductivity, oxygen-evolution potential, and stability of the BTO-CNT anode. The effectiveness and efficiency of the BTO-CNT anode as compared to the uncoated CNT was further investigated by the electrooxidative filtration of ethanol, methanol, formaldehyde, and formate, and it was determined to have TOC removals 2 to 8 times greater, mineralization current efficiencies 1.5 to 3.5 times greater, and energy consumption 4 to 5 times less than the uncoated CNT anode. Electrooxidation and anode passivation mechanisms are discussed. PMID:24040859

Liu, Han; Vajpayee, Akshay; Vecitis, Chad D

2013-10-23

183

The electroluminescence mechanism of Er{sup 3+} in different silicon oxide and silicon nitride environments  

SciTech Connect

Rare earth doped metal-oxide-semiconductor (MOS) structures are of great interest for Si-based light emission. However, several physical limitations make it difficult to achieve the performance of light emitters based on compound semiconductors. To address this point, in this work the electroluminescence (EL) excitation and quenching mechanism of Er-implanted MOS structures with different designs of the dielectric stack are investigated. The devices usually consist of an injection layer made of SiO{sub 2} and an Er-implanted layer made of SiO{sub 2}, Si-rich SiO{sub 2}, silicon nitride, or Si-rich silicon nitride. All structures implanted with Er show intense EL around 1540?nm with EL power efficiencies in the order of 2?×?10{sup ?3} (for SiO{sub 2}:Er) or 2?×?10{sup ?4} (all other matrices) for lower current densities. The EL is excited by the impact of hot electrons with an excitation cross section in the range of 0.5–1.5?×?10{sup ?15?}cm{sup ?2}. Whereas the fraction of potentially excitable Er ions in SiO{sub 2} can reach values up to 50%, five times lower values were observed for other matrices. The decrease of the EL decay time for devices with Si-rich SiO{sub 2} or Si nitride compared to SiO{sub 2} as host matrix implies an increase of the number of defects adding additional non-radiative de-excitation paths for Er{sup 3+}. For all investigated devices, EL quenching cross sections in the 10{sup ?20} cm{sup 2} range and charge-to-breakdown values in the range of 1–10 C cm{sup ?2} were measured. For the present design with a SiO{sub 2} acceleration layer, thickness reduction and the use of different host matrices did not improve the EL power efficiency or the operation lifetime, but strongly lowered the operation voltage needed to achieve intense EL.

Rebohle, L., E-mail: l.rebohle@hzdr.de; Wutzler, R.; Braun, M.; Helm, M.; Skorupa, W. [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Berencén, Y.; Ramírez, J. M.; Garrido, B. [Dept. Electrònica, Martí i Franquès 1, Universitat de Barcelona, 08028 Barcelona (Spain); Hiller, D. [IMTEK, Faculty of Engineering, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)

2014-09-28

184

Influence of dilute silicon addition on the oxidation resistance and tensile properties of modified Zircaloy-4  

NASA Astrophysics Data System (ADS)

Si-added modified Zircaloy-4 (Zry-4) and Zr-Si binary alloys were developed to evaluate the effect of silicon addition on zirconium based alloys for high burn-up application. The silicon content varied from 0 to 0.1 wt% for both the alloys. The relationships between alloy chemistry, microstructure, mechanical property and oxidation behavior were investigated. The ultimate tensile strength of the modified Zry-4 generally increased with the increase in silicon content. The optimum silicon content for improved oxidation resistance turned out to be 0.01 wt% from the weight gain measurement. The weight gain decreased with decreasing Si content from 0.1 to 0.01 wt% although the Si free specimen showed higher weight gain than the 0.01 wt% Si specimen. The details of microstuctural change with silicon addition and its influence on tensile properties and oxidation resistance are discussed; the effects of silicon on the oxide crystal structure, second phase precipitates and microstructure of the metal matrix are studied.

Hong, Hyun Seon; Kim, Seon Jin; Lee, Kyung Sub

2002-07-01

185

Fabrication of a silicon oxide stamp by edge lithography reinforced with silicon nitride for nanoimprint lithography  

Microsoft Academic Search

The fabrication of a stamp reinforced with silicon nitride is presented for its use in nanoimprint lithography. The fabrication process is based on edge lithography using conventional optical lithography and wet anisotropic etching of lang1 1 0rang silicon wafers. SiO2 nano-ridges of 20 nm in width were fabricated. A silicon rich nitride layer is deposited over the original SiO2 nano-ridges

Yiping Zhao; Erwin Berenschot; Meint de Boer; Henri Jansen; Niels Tas; Jurriaan Huskens; Miko Elwenspoek

2008-01-01

186

Method for one-to-one polishing of silicon nitride and silicon oxide  

NASA Technical Reports Server (NTRS)

The present invention provides a method of removing silicon nitride at about the same removal rate as silicon dioxide by CMP. The method utilizes a polishing slurry that includes colloidal silica abrasive particles dispersed in water and additives that modulate the silicon dioxide and silicon nitride removal rates such that they are about the same. In one embodiment of the invention, the additive is lysine or lysine mono hydrochloride in combination with picolinic acid, which is effective at a pH of about 8. In another embodiment of the invention, the additive is arginine in combination with picolinic acid, which is effective at a pH of about 10.

Babu, Suryadevara V. (Inventor); Natarajan, Anita (Inventor)

2009-01-01

187

Analysis of flicker noise for improved data retention characteristics in silicon-oxide-high-k-oxide-silicon flash memory using N2 implantation.  

PubMed

In this paper, we fabricate planar-type Silicon-Oxide-High-k-Oxide-Silicon (SOHOS) and the planar-type SOHOS devices with N2 implantation of 3 x 10(15) dose in a tunneling oxide to determine the impact of N2 implantation in the tunneling oxide of a memory device. The N2 implantation device has better retention characteristics than the device with no implantation. In order establish the correlation between N2 implantation and retention characteristic improvement, the low frequency noise (1/f noise) characteristic is investigated. The normalized drain current noise (S(ID)/I(D)2) level of the N2 implantation device is higher than that of the device with no implantation, which means that N2 implantation causes more trap formation near the interface. Considering that N2 implantation does not affect the DC transfer characteristics, such as mobility and sub-threshold slope, this finding indicates that the increase in the 1/f noise level is due to oxide traps rather than to interface traps. Therefore, the retention characteristic improvement in the N2 implantation device can be explained by the generation of higher number of oxide traps and an increase in the potential barrier blocking the leakage path in the tunneling oxide. PMID:23858853

Yang, S D; Jeong, K S; Yun, H J; Kim, Y M; Lee, S Y; Oh, J S; Lee, H D; Lee, G W

2013-05-01

188

Preparation of highly aligned silicon oxide nanowires with stable intensive photoluminescence  

NASA Astrophysics Data System (ADS)

In this work we report the successful formation of highly aligned vertical silicon oxide nanowires. The source of silicon was from the substrate itself without any additional source of silicon. X-ray measurement demonstrated that our nanowires are amorphous. Photoluminescence measurements were conducted through 18 months and indicated that there is a very good intensive emission peaks near the violet regions. The FTIR measurements indicated the existence of peaks at 463, 604, 795 and a wide peak at 1111 cm -1 and this can be attributed to Si-O-Si and Si-O stretching vibrations. We also report the formation of the octopus-like silicon oxide nanowires and the growth mechanism of these structures was discussed.

Duraia, El-Shazly M.; Mansurov, Z. A.; Tokmolden, S.; Beall, Gary W.

2010-02-01

189

Selective surface modification of lithographic silicon oxide nanostructures by organofunctional silanes  

PubMed Central

Summary This study investigates the controlled chemical functionalization of silicon oxide nanostructures prepared by AFM-anodization lithography of alkyl-terminated silicon. Different conditions for the growth of covalently bound mono-, multi- or submonolayers of distinctively functional silane molecules on nanostructures have been identified by AFM-height investigations. Routes for the preparation of methyl- or amino-terminated structures or silicon surfaces are presented and discussed. The formation of silane monolayers on nanoscopic silicon oxide nanostructures was found to be much more sensitive towards ambient humidity than, e.g., the silanization of larger OH-terminated silica surfaces. Amino-functionalized nanostructures have been successfully modified by the covalent binding of functional fluorescein dye molecules. Upon excitation, the dye-functionalized structures show only weak fluorescence, which may be an indication of a relatively low surface coverage of the dye molecules on length scale that is not accessible by standard AFM measurements. PMID:23616941

von Borczyskowski, Christian; Graaf, Harald

2013-01-01

190

Hot-pressing behaviour of silicon carbide powders with additions of aluminium oxide  

Microsoft Academic Search

The hot-pressing behaviour of different silicon carbide powders (average particle sizes ranging from ~ 0.5 to 9 µm) with aluminium oxide additions ranging from 0.01 to 0.15 volume fractions was investigated. Using powders with an average particle size -2 for volume fractions of AI2O3\\u000a$$\\\\bar > $$\\u000a 0.02. A liquid phase forms at high temperatures which dissolves the silicon carbide

F. F. Lange

1975-01-01

191

Bismuth-doped germanosilicate fibre laser with 20-W output power at 1460 nm  

SciTech Connect

We report the first cw bismuth - germanium codoped silica fibre laser with an output power above 20 W at 1460 nm and 50% optical efficiency. The laser operates on a transition between energy levels of bismuth-related active centres associated with silicon. The incorporation of a small amount ({approx}5 mol %) of germanium into the core of bismuth-doped silica fibre has little effect on its luminescence spectrum but reduces optical losses, which limit the laser efficiency. (letters)

Firstov, Sergei V; Shubin, Aleksei V; Khopin, V F; Mel'kumov, Mikhail A; Bufetov, Igor' A; Medvedkov, O I; Gur'yanov, Aleksei N; Dianov, Evgenii M

2011-07-31

192

Magnetic nanocables—Silicon carbide sheathed with iron-oxide-doped amorphous silica  

NASA Astrophysics Data System (ADS)

High-purity nanocables of iron-containing amorphous-silica-sheathed silicon carbide were synthesized by a thermal reaction method using silicon wafer as the silicon source and growth substrate, and ferrocene as the carbon and iron catalyst precursor. The nanocables were tens of ?m in length and 40-60nm in diameter. Iron oxide nanoparticles with a mean diameter of 5nm were dispersed evenly in the amorphous silica layer. The nanocables were found to be ferromagnetic at both 10K and room temperature, which indicates that they may have important potential applications in electromagnetic nanodevices.

Liu, C.; Li, R. W.; Belik, A.; Golberg, D.; Bando, Y.; Cheng, H. M.

2006-01-01

193

Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy  

PubMed Central

We present a titanium-silicon oxide film structure that permits polarization modulated infrared reflection absorption spectroscopy on silicon oxide surfaces. The structure consists of a ~6 nm sputtered silicon oxide film on a ~200 nm sputtered titanium film. Characterization using conventional and scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectometry is presented. We demonstrate the use of this structure to investigate a selectively protein-resistant self-assembled monolayer (SAM) consisting of silane-anchored, biotin-terminated poly(ethylene glycol) (PEG). PEG-associated IR bands were observed. Measurements of protein-characteristic band intensities showed that this SAM adsorbed streptavidin whereas it repelled bovine serum albumin, as had been expected from its structure. PMID:20418963

Dunlop, Iain E.; Zorn, Stefan; Richter, Gunther; Srot, Vesna; Kelsch, Marion; van Aken, Peter A.; Skoda, Maximilian; Gerlach, Alexander; Spatz, Joachim P.; Schreiber, Frank

2010-01-01

194

The effect of oxidations on phosphorus-diffused crystalline-silicon substrates  

SciTech Connect

The authors examined the effect of oxidation on phosphorus-diffused crystalline-silicon p-type substrates. Oxidations subsequent to the phosphorus diffusion are of interest for passivating surfaces, and are commonly found in both high-efficiency laboratory-cell and commercial-cell fabrication sequences. The authors found a degradation of the bulk lifetime due to the oxidation in a variety of crystalline-silicon substrates that were diffused in various laboratories. The degradation was avoided if there was aluminum present on the back surface of the wafer during the oxidation. The study suggests that impurities gettered during the phosphorus diffusion can be released back into the bulk during a subsequent oxidation, and that the aluminum suppressed the bulk lifetime degradation by reabsorbing these released impurities.

Gee, J.M. [Sandia National Labs., Albuquerque, NM (United States); King, R.R.; Reiss, J.H.; Mitchell, K.W. [Siemens Solar Industries, Camarillo, CA (United States); Narayanan, S. [Solarex, Frederick, MD (United States)

1997-08-01

195

Effective surface passivation of p-type crystalline silicon with silicon oxides formed by light-induced anodisation  

NASA Astrophysics Data System (ADS)

Electronic surface passivation of p-type crystalline silicon by anodic silicon dioxide (SiO2) was investigated. The anodic SiO2 was grown by light-induced anodisation (LIA) in diluted sulphuric acid at room temperature, a process that is significantly less-expensive than thermal oxidation which is widely-used in silicon solar cell fabrication. After annealing in oxygen and then forming gas at 400 °C for 30 min, the effective minority carrier lifetime of 3-5 ? cm, boron-doped Czochralski silicon wafers with a phosphorus-doped 80 ?/? emitter and a LIA anodic SiO2 formed on the p-type surface was increased by two orders of magnitude to 150 ?s. Capacitance-voltage measurements demonstrated a very low positive charge density of 3.4 × 1011 cm-2 and a moderate density of interface states of 6 × 1011 eV-1 cm-2. This corresponded to a silicon surface recombination velocity of 62 cm s-1, which is comparable with values reported for other anodic SiO2 films, which required higher temperatures and longer growth times, and significantly lower than oxides grown by chemical vapour deposition techniques. Additionally, a very low leakage current density of 3.5 × 10-10 and 1.6 × 10-9 A cm-2 at 1 and -1 V, respectively, was measured for LIA SiO2 suggesting its potential application as insulation layer in IBC solar cells and a barrier for potential induced degradation.

Cui, Jie; Grant, Nicholas; Lennon, Alison

2014-12-01

196

Real-time observation of initial stages of copper film growth on silicon oxide using reflection high-energy electron diffraction  

E-print Network

clean silicon surfaces have revealed that copper and silicon interact strongly, forming copper silicideReal-time observation of initial stages of copper film growth on silicon oxide using reflection (less than 200 Ã?) copper film deposited onto an oxidized silicon surface using reflection high

Wang, Gwo-Ching

197

Quantitative comparison of the doubly integrated KLL Auger spectra of magnesium, aluminum, and silicon with their oxides  

Microsoft Academic Search

Integrals, over selected electron energies, E, of magnesium, aluminum, and silicon KLL Auger spectra of magnesium, aluminum, silicon, and their oxides have been measured directly using tailored modulation techniques. The ratios of Auger currents, I(E), measured in this way from the metals and their respective oxides have been determined and are compared with the corresponding atomic densities of magnesium, aluminum,

R. W. Springer; T. W. Haas; J. T. Grant

1978-01-01

198

Facile preparation of highly-dispersed cobalt-silicon mixed oxide nanosphere and its catalytic application in cyclohexane selective oxidation  

PubMed Central

Highly dispersed cobalt-silicon mixed oxide [Co-SiO2] nanosphere was successfully prepared with a modified reverse-phase microemulsion method. This material was characterized in detail by X-ray diffraction, transmission electron microscopy, Fourier transform infrared, ultraviolet-visible diffuse reflectance spectra, X-ray absorption spectroscopy near-edge structure, and N2 adsorption-desorption measurements. High valence state cobalt could be easily obtained without calcination, which is fascinating for the catalytic application for its strong oxidation ability. In the selective oxidation of cyclohexane, Co-SiO2 acted as an efficient catalyst, and good activity could be obtained under mild conditions. PMID:22067075

2011-01-01

199

Oxidation of Chemically-Vapor-Deposited Silicon Carbide in Carbon Dioxide  

NASA Technical Reports Server (NTRS)

Chemically-vapor-deposited silicon carbide (CVD SiC) was oxidized in carbon dioxide (CO2) at temperatures of 1200-1400 C for times between 96 and 500 h at several gas flow rates. Oxidation weight gains were monitored by thermogravimetric analysis (TGA) and were found to be very small and independent of temperature. Possible rate limiting kinetic mechanisms are discussed. Passive oxidation of SiC by CO2 is negligible compared to the rates measured for other oxidants that are also found in combustion environments, oxygen and water vapor.

Opila, Elizabeth J.; Nguyen, QuynhGiao N.

1998-01-01

200

Improvement in gate oxide integrity on thin-film silicon-on-insulator substrates by lateral gettering  

E-print Network

Improvement in gate oxide integrity on thin-film silicon-on-insulator substrates by lateral defects in the vicinity of metal-oxide-semiconductor device channel regions prior to gate oxidation. As a result of the gettering a significant improvement in gate oxide integrity is achieved, with increased

Schroder, Dieter K.

201

Investigation of Low Temperature, Atomic-Layer-Deposited Oxides on 4Hydrigen-Silicon Carbide and their Effect on the Silicon Carbide/Silicon Dioxide Interface  

NASA Astrophysics Data System (ADS)

Silicon carbide has long been considered an excellent substrate for high power, high temperature applications. Fabrication of conventional MOSFETs on silicon carbide (SiC) relies on thermal oxidation of the SiC for formation of the silicon dioxide (SiO2) gate oxide. Historically, direct oxidation was viewed favorably due to ease of fabrication. However, the resulting MOS devices have exhibited significant interface trap densities, Dit , which reduce effective inversion layer mobility by capturing free carriers and enhancing scattering. While nitridation has been shown to reduce Dit, the inversion layer electron mobility of these devices is still limited by the presence of carbon near the interface. Studies have suggested a low mobility transition region between the SiC and SiO2, on the SiC side, attributed to increased carbon concentration resulting from the thermal oxidation of the SiC. In this work, we have investigated the low temperature, atomic layer deposition (ALD) of SiO2 onto SiC compared to thermal oxidation of SiC for the fabrication of MOS devices. Avoiding the carbon out diffusion and subsequent carbon build-up resulting from thermal oxidation is expected to result in a superior, higher mobility MOSFET. A three-step ALD process using 3-aminopropyltriethoxysiliane (3-APTES), ozone and water was evaluated on silicon and SiC substrates. Ellipsometry and XPS were used to characterize blanket films, and showed good results. Capacitors fabricated on SiC showed the need for optimized post deposition anneals. The effect of post oxidation anneals in nitrogen, forming gas and nitric oxide were examined. The standard nitric oxide (NO) anneal that is used to improve Dit after thermal oxidation was also shown to be the best anneal for the low temperature deposited ALD oxides. Materials characterization of the nitrided ALD and nitrided thermal oxide samples was completed using STEM/EELS techniques in addition to the ellipsometry and XPS. STEM/EELS analysis of the samples revealed no significant difference in transition regions on either side of the SiC/SiO2 interface regardless of oxidation technique or anneal temperature or ambient. All samples analyzed exhibited approximately 2-3nm of transition region on either side of the interface with no evidence of carbon or silicon rich regions. XPS was also used to determine a valence band offset of 2.43eV for the ALD oxide on 4H-SiC. Lateral MOSFETs were fabricated on 4H-SiC substrates with the following oxidation treatments: thermal oxidation at 1175°C, thermal oxidation at 1175°C followed by a nitric oxide (NO) anneal at 1175°C, and ALD of SiC at 150°C followed by an NO post oxidation anneal (POA) at 1175°C. ALD of the SiO2 was performed using 3-aminopropyltriethoxysiliane (3-APTES), ozone and water. Field effect mobility values were comparable for these samples, suggesting common thermal oxidation steps were still limiting the mobility. As such additional lateral MOSFETs were fabricated without the incoming sacrificial oxidation steps. This sacrificial-oxidation free experiment showed a 15% improvement in peak field effect mobility for the nitrided ALD oxide samples as compared to the nitrided thermal oxides. SIMS of the interfaces revealed nitrogen concentrations of ˜6E21 at/cc in the nitrided ALD sample compared to ˜4-6E20 in the nitrided thermal sample. This extremely high level of nitrogen incorporation, which is unparalleled in NO annealed thermal oxides, is accountable for the increase in field effect mobility. The low deposition temperature of the ALD oxide causes high levels of carbon incorporation and greater number of dangling bonds at the interface. Both the dangling bonds and excess carbon acts as binding sites for the nitrogen, increasing the nitrogen concentration and resulting in higher mobilities. Results presented support the use of SiO2 deposited using low temperature atomic layer deposition for improved gate oxides on 4H-SiC MOSFETs given the opportunity for increased nitrogen incorporation. The elevated levels of nitrogen measured in the NO annealed

Haney, Sarah Kay

202

Low-index nanopatterned barrier for hybrid oxide-free III-V silicon conductive bonding.  

PubMed

Oxide-free bonding of a III-V active stack emitting at 1300-1600 nm to a silicon-on-insulator wafer offers the capability to electrically inject lasers from the silicon side. However, a typical 500-nm-thick silicon layer notably attracts the fundamental guided mode of the silicon + III-V stack, a detrimental feature compared to established III-V Separate-Confinement Heterostructure (SCH) stacks. We experimentally probe with photoluminescence as an internal light source the guiding behavior for oxide-free bonding to a nanopatterned silicon wafer that acts as a low-index barrier. We use a sub-wavelength square array of small holes as an effective "low-index silicon" medium. It is weakly modulated along one dimension (superperiodic array) to outcouple the resulting guided modes to free space, where we use an angle-resolved spectroscopy study. Analysis of experimental branches confirms the capability to operate with a fundamental mode well localized in the III-V heterostructures. PMID:25321802

Bougot-Robin, Kristelle; Talneau, Anne; Benisty, Henri

2014-09-22

203

Synthesis of silicon oxide nanowires and nanotubes with cobalt-palladium or palladium catalysts  

NASA Astrophysics Data System (ADS)

The dewetting behaviors of cobalt (Co), cobalt palladium (CoPd), and palladium (Pd) thin films on oxidized silicon substrates were examined. We observed the formation of craters in the oxide layer and pits in the Si substrate for larger CoPd or Pd catalyst particles and thinner oxide. Nanowires and nanotubes were observed near the Si pits. The nanowires and nanotubes grow via a vapor-solid-solid or vapor-liquid-solid mechanism with the silicon vapor source provided from the substrate. The original Si atoms that form the nanowires or nanotubes were oxidized in situ by the residual oxygen atoms present in the chamber. Some of the nanotubes had a series of embedded sub-catalysts that formed branches from the primary nanotube.

Esterina, Ria; Liu, X. M.; Ross, C. A.; Adeyeye, A. O.; Choi, W. K.

2012-07-01

204

Formation of titanium oxide films on the surface of porous silicon carbide  

Microsoft Academic Search

The influence of rapid thermal annealing (RTA) on the properties of a titanium film on the surface of porous silicon carbide\\u000a is considered. It is shown that an increase in the RTA temperature to 900°C stabilizes the phase composition of the forming\\u000a titanium oxide over the film, which is identified as rutile. Due to the formation of titanium oxide nanoclusters

Yu. Yu. Bacherikov; N. L. Dmitruk; R. V. Konakova; O. S. Kondratenko; V. V. Milenin; O. B. Okhrimenko; L. M. Kapitanchuk; A. M. Svetlichnyi; N. N. Moskovchenko

2008-01-01

205

Low temperature growth of crystalline magnesium oxide on hexagonal silicon carbide (0001) by molecular beam epitaxy  

Microsoft Academic Search

Magnesium oxide (111) was grown epitaxially on hexagonal silicon carbide (6H-SiC) (0001) substrates at low temperatures by molecular beam epitaxy and a remote oxygen plasma source. The films were characterized by reflection high-energy electron diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. Crystal structure, morphology, and growth rate of the magnesium oxide (MgO) films were found to

T. L. Goodrich; J. Parisi; Z. Cai; K. S. Ziemer

2007-01-01

206

A Model for the Oxidation of Carbon Silicon Carbide Composite Structures  

NASA Technical Reports Server (NTRS)

A mathematical theory and an accompanying numerical scheme have been developed for predicting the oxidation behavior of carbon silicon carbide (C/SiC) composite structures. The theory is derived from the mechanics of the flow of ideal gases through a porous solid. The result of the theoretical formulation is a set of two coupled nonlinear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The nonlinear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual method, allowing for the solution of the differential equations numerically. The numerical method is demonstrated by utilizing the method to model the carbon oxidation and weight loss behavior of C/SiC specimens during thermogravimetric experiments. The numerical method is used to study the physics of carbon oxidation in carbon silicon carbide composites.

Sullivan, Roy M.

2004-01-01

207

Configurational statistical model for the damaged structure of silicon oxide after ion implantation  

NASA Astrophysics Data System (ADS)

A configurational model for silicon oxide damaged after a high-dose ion implantation of a nonreactive species is presented. Based on statistics of silicon-centered tetrahedra, the model takes into account not only the closest environment of a given silicon atom, but also the second neighborhood, so it is specified whether the oxygen attached to one given silicon is bridging two tetrahedra or not. The frequencies and intensities of infrared vibrational bands have been calculated by averaging over the distributions and these results are in agreement with the ones obtained from infrared experimental spectra. Likewise, the chemical shifts obtained from x-ray photoelectron spectroscopy (XPS) analysis are similar to the reported values for the charge-transfer model of SiOx compounds.

Garrido, B.; Samitier, J.; Morante, J. R.; Montserrat, J.; Domínguez, C.

1994-06-01

208

Suppression of subcutaneous oxidation during the deposition of amorphous lanthanum aluminate on silicon  

NASA Astrophysics Data System (ADS)

Amorphous LaAlO3 thin films have been deposited by molecular beam deposition directly on silicon without detectable oxidation of the underlying substrate. We have studied these abrupt interfaces by Auger electron spectroscopy, high-resolution transmission electron microscopy, medium-energy ion scattering, transmission infrared absorption spectroscopy, and x-ray photoelectron spectroscopy. Together these techniques indicate that the films are fully oxidized and have less than 0.2 Å of SiO2 at the interface between the amorphous LaAlO3 and silicon. These heterostructures are being investigated for alternative gate dielectric applications and provide an opportunity to control the interface between the silicon and the gate dielectric.

Edge, L. F.; Schlom, D. G.; Brewer, R. T.; Chabal, Y. J.; Williams, J. R.; Chambers, S. A.; Hinkle, C.; Lucovsky, G.; Yang, Y.; Stemmer, S.; Copel, M.; Holländer, B.; Schubert, J.

2004-06-01

209

Detection of an Oxygen-Excessive Layer in Thermally Grown Silicon Oxide  

Microsoft Academic Search

This paper describes depth profiling of the oxygen (O) content of thermally grown silicon oxide by Auger electron spectroscopy (AES). In this approach, the Auger peak area value obtained by integrating the first-derivative spectrum is used as the signal intensity. After profiling of a number of similar samples, the average values of signal intensities for the same depths are plotted

Yoshio Watanabe

1995-01-01

210

Metal-oxide--n--p--p/sup +/ solar cells on silicon tape  

SciTech Connect

This letter reports a study of solar cells with the MO--n--p--p/sup +/ structure (MO is a metal oxide) fabricated on silicon tapes grown from the melt by the Stepanov method with a dense graphite form wettable by the melt.(AIP)

Abrosimov, N.V.; Bazhenov, A.V.; Baranyuk, V.B.; Brantov, S.K.; Malik, A.I.; Manasson, V.A.; Tatarchenko, V.A.

1982-12-01

211

In vitro inflammatory response of nanostructured titania, silicon oxide, and polycaprolactone.  

PubMed

Nanostructured materials are ubiquitous in tissue engineering, drug delivery, and biosensing applications. Nonetheless, little is known about the inflammatory response of materials differing in surface nanoarchitecture. Here we report human monocyte viability and morphology, in addition to inflammatory cytokines (IL-1alpha and B, IL-6, IL-10, IFN-alpha and gamma, TNF-alpha, IL-12, MIP-1alpha and beta), and reactive oxygen species production on several nanostructured surfaces, compared to flat surfaces of the same material. The surfaces studied were titiania nanotubes, short and long silicon oxide, and polycaprolactone nanowires. The results indicate that inflammation on titanium, polycaprolactone, and silicon oxide materials can be reduced by restructuring the surface with nanoarchitecture. Nanostructured surfaces display a reduced inflammation response compared to a respective flat control, with significant differences between titanium and nanotubular titanium. Little difference is observed in the inflammatory response between short and long nanowires of PCL and silicon oxide. All surfaces are significantly less inflammatory than the positive control, lipopolysaccharide. Additionally, we show that flat titanium is more inflammatory than silicon oxide and polycaprolactone. This study shows that nanoarchitecture can be used to reduce the inflammatory response of human monocytes in vitro. PMID:18988278

Ainslie, Kristy M; Tao, Sarah L; Popat, Ketul C; Daniels, Hugh; Hardev, Veeral; Grimes, Craig A; Desai, Tejal A

2009-12-01

212

Metal Oxide Silicon /MOS/ transistors protected from destructive damage by wire  

NASA Technical Reports Server (NTRS)

Loop of flexible, small diameter, nickel wire protects metal oxide silicon /MOS/ transistors from a damaging electrostatic potential. The wire is attached to a music-wire spring, slipped over the MOS transistor case, and released so the spring tensions the wire loop around all the transistor leads, shorting them together. This allows handling without danger of damage.

Deboo, G. J.; Devine, E. J.

1966-01-01

213

Giant isotope effect in hot electron degradation of metal oxide silicon devices  

Microsoft Academic Search

A giant isotope effect of hot electron degradation was found by annealing and passivating integrated circuits of recent complementary metal oxide silicon (CMOS) technology with deuterium instead of hydrogen. In this paper, we summarize our experience and present new results of secondary ion mass spectroscopy that correlate deuterium accumulation with reduced hot electron degradation. We also present a first account

Karl Hess; Isik C. Kizilyalli; Joseph W. Lyding

1998-01-01

214

Metal Impurity Trapping Effect by Stress at Edges of Local Oxidation of Silicon Structure  

Microsoft Academic Search

In this study, the direct relationship between stress at edges of the local oxidation of silicon (LOCOS) structure and Fe atoms was investigated employing secondary ion mass spectroscopy (SIMS), total reflection X-ray fluorescence (TXRF), transmission electron microscopy (TEM), and optical microscopy. Fe atoms contaminated from the back of the wafer diffused to the front surface during the drive-in annealing and

Shun-ichiro Ishigami; Satoru Ishii; Hiroshi Shinyashiki; Hisashi Furuya; Takayuki Shingyouji

1994-01-01

215

DNA-Mediated Fluctuations in Ionic Current through Silicon Oxide Nanopore  

E-print Network

DNA-Mediated Fluctuations in Ionic Current through Silicon Oxide Nanopore Channels H. Chang, F the nanopore sensors is that there exists no electrical interaction between the nanopore and the translocating molecule, and that all nanopore sensors reported to-date, whether biological or artificial, operate

Bashir, Rashid

216

Electron stimulated oxidation and rhenium electrical contacts on alpha-silicon carbide  

NASA Astrophysics Data System (ADS)

Electron stimulated oxidation (ESO) and rhenium (Re) metallizations on alpha-silicon carbide (6H-SiC) were studied. ESO was quantified versus electron beam exposure, total vacuum pressure, beam energy Ep (3 to 6 keV), and current Ip (25 to 500 nA), while monitoring chemical change using Auger electron spectroscopy (AES). Vacuum chamber pressures below 2.6 x 10 -8 Torr required beam irradiation to induce oxidation. A positive linear correlation between oxidation rate and total chamber pressure was observed. Rate did not correlate with concentration of a particular ambient species (H2O, CO, or CO2). Oxidation rate decreased with increased Ep suggesting surface secondary electrons stimulate oxidation. Dependence of oxidation rate on Ip indicated current limited dissociation below 200 nA. Rhenium contacts (1000 angstroms thick) were deposited on carbon-rich, stoichiometric, and silicon-rich 6H-SiC surfaces. Morphology (Dektak), texture (X-ray diffraction (XRD)), chemistry (AES), and electrical properties (current/voltage (I--V)) were characterized for as-deposited and annealed (120 minute, 1000°C, <1 x 10-6 Torr) contacts. As-deposited films were non-ohmic with total contact resistances of 59, 1620 and 110 ohms for carbon-rich, stoichiometric, and silicon-rich surfaces, respectively. Films grown on carbon-rich surfaces were non-specular, granular, and often delaminated during characterization. Island-growth was observed on stoichiometric surfaces with thickness variations of ˜800 angstroms. Films remained specular for 3 hours, but then became hazy from oxidation. Textured (101) growth was observed on silicon-rich surfaces. Thickness varied by ˜250 angstroms and films resisted ex-situ oxidation for more than 24 hours. Annealed samples remained specular without visual signs of oxidation. Films were smoothed with thickness variance less than 100 angstroms. Phase separation was observed based on formation of interfacial Re clusters and ˜100 angstrom graphite surface layers. Auger confirmed as-deposited Si layers (50 to 100 angstroms) were consumed by reaction during annealing and Re/Si and Si/SiC interfaces were diffused ˜500 angstroms more compared to as-deposited interfaces. Annealed contacts were largely ohmic with averaged total contact resistances reduced to 11,3.2, and 1.4O for carbon-rich, stoichiometric, and silicon-rich samples, respectively. Average specific contact resistances of 7.0 x 10-5 Ocm2 for stoichiometric and 1.6 x 10-5 Ocm2 for silicon-rich samples were observed.

McDaniel, Gavin Young

217

Analyses of silicon dioxide, magnesium oxide, lead fluoride, bismuth as low-pass velocity filters for neutrons  

NASA Technical Reports Server (NTRS)

Transmission measurement of neutrons by filter materials for low energy neutrons is important for the study of structure and dynamics of condensed matter. Since only thermal neutrons are useful for such experiments, filter materials that transmit thermal neutrons while attenuating fast neutrons and gamma rays are of considerable interest.

Connor, D.; Holmryd, S.

1969-01-01

218

Bismuth as a modifier of Au Pd catalyst: Enhancing selectivity in alcohol oxidation by suppressing parallel reaction  

SciTech Connect

Bi has been widely employed as a modifier for Pd and Pt based catalyst mainly in order to improve selectivity. We found that when Bi was added to the bimetallic system AuPd, the effect on activity in alcohol oxidation mainly depends on the amount of Bi regardless its position, being negligible when Bi was 0.1 wt% and detectably negative when the amount was increased to 3 wt%. However, the selectivity of the reactions notably varied only when Bi was deposited on the surface of metal nanoparticles suppressing parallel reaction in both benzyl alcohol and glycerol oxidation. After a careful characterization of all the catalysts and additional catalytic tests, we concluded that the Bi influence on the activity of the catalysts could be ascribed to electronic effect whereas the one on selectivity mainly to a geometric modification. Moreover, the Bi-modified AuPd/AC catalyst showed possible application in the production of tartronic acid, a useful intermediate, from glycerol.

Villa, Alberto [Universita di Milano, Italy; Wang, Di [Fritz Haber Institute of the Max Planck Society, Berlin, Germany; Veith, Gabriel M [ORNL; Prati, Laura [Universita di Milano, Italy

2012-01-01

219

Fabrication of disposable topographic silicon oxide from sawtoothed patterns: control of arrays of gold nanoparticles.  

PubMed

Disposable topographic silicon oxide patterns were fabricated from polymeric replicas of sawtoothed glass surfaces, spin-coating of poly(dimethylsiloxane) (PDMS) thin films, and thermal annealing at certain temperature and followed by oxygen plasma treatment of the thin PDMS layer. A simple imprinting process was used to fabricate the replicated PDMS and PS patterns from sawtoothed glass surfaces. Next, thin layers of PDMS films having different thicknesses were spin-coated onto the sawtoothed PS surfaces and annealed at 60 degrees C to be drawn the PDMS into the valley of the sawtoothed PS surfaces, followed by oxygen plasma treatment to fabricate topographic silicon oxide patterns. By control of the thickness of PDMS layers, silicon oxide patterns having various line widths were fabricated. The silicon oxide topographic patterns were used to direct the self-assembly of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer thin films via solvent annealing process. A highly ordered PS-b-P2VP micellar structure was used to let gold precursor complex with P2VP chains, and followed by oxygen plasma treatment. When the PS-b-P2VP thin films containing gold salts were exposed to oxygen plasma environments, gold salts were reduced to pure gold nanoparticles without changing high degree of lateral order, while polymers were completely degraded. As the width of trough and crest in topographic patterns increases, the number of gold arrays and size of gold nanoparticles are tuned. In the final step, the silicon oxide topographic patterns were selectively removed by wet etching process without changing the arrays of gold nanoparticles. PMID:20000759

Cho, Heesook; Yoo, Hana; Park, Soojin

2010-05-18

220

Microcrystalline silicon oxides for silicon-based solar cells: impact of the O/Si ratio on the electronic structure  

NASA Astrophysics Data System (ADS)

Hydrogenated microcrystalline silicon oxide (?c-SiOx:H) layers are one alternative approach to ensure sufficient interlayer charge transport while maintaining high transparency and good passivation in Si-based solar cells. We have used a combination of complementary x-ray and electron spectroscopies to study the chemical and electronic structure of the (?c-SiOx:H) material system. With these techniques, we monitor the transition from a purely Si-based crystalline bonding network to a silicon oxide dominated environment, coinciding with a significant decrease of the material's conductivity. Most Si-based solar cell structures contain emitter/contact/passivation layers. Ideally, these layers fulfill their desired task (i.e., induce a sufficiently high internal electric field, ensure a good electric contact, and passivate the interfaces of the absorber) without absorbing light. Usually this leads to a trade-off in which a higher transparency can only be realized at the expense of the layer's ability to properly fulfill its task. One alternative approach is to use hydrogenated microcrystalline silicon oxide (?c-SiOx:H), a mixture of microcrystalline silicon and amorphous silicon (sub)oxide. The crystalline Si regions allow charge transport, while the oxide matrix maintains a high transparency. To date, it is still unclear how in detail the oxygen content influences the electronic structure of the ?c-SiOx:H mixed phase material. To address this question, we have studied the chemical and electronic structure of the ?c-SiOx:H (0 <= x = O/Si <=1) system with a combination of complementary x-ray and electron spectroscopies. The different surface sensitivities of the employed techniques help to reduce the impact of surface oxides on the spectral interpretation. For all samples, we find the valence band maximum to be located at a similar energy with respect to the Fermi energy. However, for x > 0.5, we observe a pronounced decrease of Si 3s - Si 3p hybridization in favor of Si 3p - O 2p hybridization in the upper valence band. This coincides with a significant increase of the material's resistivity, possibly indicating the breakdown of the conducting crystalline Si network. Silicon oxide layers with a thickness of several hundred nanometres were deposited in a PECVD (plasma-enhanced chemical vapor deposition) multi chamber system using an excitation frequency of 13.56 MHz with a plasma power density of 0.3 W/cm2. Glass (Corning type Eagle) and mono-crystalline silicon wafer substrates were coated in the same run at a substrate temperature of 185°C. The deposition pressure was 4 mbar and the substrate-electrode distance 20 mm. Mixtures of silane (SiH4), 1% TMB (B(CH3)3) diluted in helium, hydrogen (H2), and carbon dioxide (CO2) gases were used at flow rates of 1.25 - 0.18/0.32/500/0 - 1.07) sccm (standard cubic centimeters per minute) for the deposition of ?c-SiOx:H(B) layers. By changing the CO2/SiH4 gas flow rate ratio from 0 to 6, ?c-SiOx:H(B) layers with a composition of 0 <=? x = O/Si ?<= 1 were prepared using a constant sum of SiH4 and CO2. The TMB flow and the H2 flow were kept constant within the series. For more details see Ref. [1]. The oxygen content in the films was determined using Rutherford Backscattering Spectroscopy (RBS). With RBS, the area-related atomic density of oxygen and silicon can be determined (+/- 2% [2]), and thus x can be calculated. This quantity considers only the number of silicon / oxygen atoms and not the number of atoms of other elements, such as hydrogen, which is also incorporated to a considerable extent: up to 20% in ?c-SiOx:H (measured using the hydrogen effusion method). To avoid charging effects, the measurements were performed on films deposited on a substrate of mono-crystalline silicon wafers. The electrical conductivity was measured in the planar direction of the film in a vacuum cryostat, using voltages from - 100 V to + 100 V. For that two co-planar Ag contacts were evaporated on the film with a gap of 0.5 mm - 5 mm. In the present study, the

Bär, M.; Starr, D. E.; Lambertz, A.; Holländer, B.; Alsmeier, J.-H.; Weinhardt, L.; Blum, M.; Gorgoi, M.; Yang, W.; Wilks, R. G.; Heske, C.

2014-10-01

221

Oxidation Kinetics of Chemically Vapor-Deposited Silicon Carbide in Wet Oxygen  

NASA Technical Reports Server (NTRS)

The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

Opila, Elizabeth J.

1994-01-01

222

Oxidation and sulfidation resistant alloys with silicon additions  

SciTech Connect

The Albany Research Center (ARC) has considerable experience in developing lean chromium, austenitic stainless steels with improved high temperature oxidation resistance. Using basic alloy design principles, a baseline composition of Fe-16Cr-16Ni-2Mn-1Mo alloys with Si and Al addition at a maximum of 5 weight percent was selected for potential application at temperatures above 700ºC for supercritical and ultra-supercritical power plant application. The alloys were fully austenitic. Cyclic oxidation tests in air for 1000 hours were carried out on alloys with Si only or combined Si and Al additions in the temperature range 700ºC to 800ºC. Oxidation resistances of alloys with Si only additions were outstanding, particularly at 800ºC (i.e., these alloys possessed weight gains 4 times less than a standard type-304 alloy). In addition, Si alloys pre-oxidized at 800ºC, showed a zero weight gain in subsequent testing for 1000 hours at 700ºC. Similar improvements were observed for Si only alloy after H2S exposure at 700ºC compared with type 304 stainless steel. SEM and ESCA analysis of the oxide films and base material at the oxide/base metal interface were conducted to study potential rate controlling mechanisms at ARC. Depth profile analysis and element concentration profiles (argon ion etching/x-ray photoelectron spectroscopy) were conducted on oxidized specimens and base material at the National Energy Technology Laboratory.

Dunning, John S.; Alman, David E.; Poston, J.A., Jr. (NETL); Siriwardane, R. (NETL)

2003-01-01

223

The high-temperature oxidation, reduction, and volatilization reactions of silicon and silicon carbide  

Microsoft Academic Search

A thermochemical analysis was made of the oxidation, reduction, and volatilization reactions which occur in the Si-O-C system. One characteristic feature is the high SiO(g) and SiO(g) + CO(g) pressures at the Si(s)-SiO2 and SiC(s)-SiO2(s) interfaces. Active oxidation with weight losses and passive oxidation with weight gains were found on oxidizing Si(s) and SiC(s) in low oxygen pressures above 1000°C.

Earl A. Gulbransen; Sven A. Jansson

1972-01-01

224

Experimental study of the oxidation of silicon germanium alloys  

NASA Astrophysics Data System (ADS)

We report on the in situ oxidation of a series of Si-Ge alloy layers grown epitaxially on a (100) Si substrate. The alloy compositions of the layers varied in Ge composition from 1.8% to a high of 16.8%. Oxidations were carried out in situ in a Scientia ESCA-300 system between 400 and 800 °C. In order to explore the transition from pure SiO2 to mixed SiO2-GeO2 films, dry oxidations were carried out under partial pressures which were varied by almost nine orders of magnitude. State of the art oxidations were also carried out in a double walled oxidation furnace at one atmosphere to compare with some of the published results. In situ oxidations and analyses were done at each stage of the process from initial cleaning to monolayer absorption and oxide formation. Films grown in the thin regime up to 10 nm were analyzed by angle resolved x-ray spectroscopy. These studies were carried out to explore the influence of alloy composition on the distribution of subbonded states of Si and their influence on interfacial properties. Comparisons were made between films that were grown as pure SiO2 and those that resulted in mixed SiO2-GeO2 with regard to the areal density of these states. In spite of the strong pileup of Ge at the interface during oxide growth, there was less than expected influence of alloy composition on the interface and some evidence that interfacial annealing was taking place. It was also confirmed that mixed oxide interfaces were poorer and more highly defective than those of pure SiO2 on the same alloy.

Kilpatrick, S. J.; Jaccodine, R. J.; Thompson, P. E.

2003-04-01

225

Optical properties of bismuth-doped silica fibres in the temperature range 300 - 1500 K  

SciTech Connect

The visible and near-IR absorption and luminescence bands of bismuth-doped silica and germanosilicate fibres have been measured for the first time as a function of temperature. The temperature-dependent IR luminescence lifetime of a bismuth-related active centre associated with silicon in the germanosilicate fibre has been determined. The Bi{sup 3+} profile across the silica fibre preform is shown to differ markedly from the distribution of IR-emitting bismuth centres associated with silicon. The present results strongly suggest that the IR-emitting bismuth centre comprises a lowvalence bismuth ion and an oxygen-deficient glass network defect. (optical fibres, lasers and amplifiers. properties and applications)

Dvoretskii, D A; Bufetov, Igor' A; Vel'miskin, V V; Zlenko, Alexander S; Khopin, V F; Semjonov, S L; Guryanov, Aleksei N; Denisov, L K; Dianov, Evgenii M

2012-09-30

226

Graphene oxide-immobilized NH?-terminated silicon nanoparticles by cross-linked interactions for highly stable silicon negative electrodes.  

PubMed

There is a great interest in the utilization of silicon-based anodes for lithium-ion batteries. However, its poor cycling stability, which is caused by a dramatic volume change during lithium-ion intercalation, and intrinsic low electric conductivity hamper its industrial applications. A facile strategy is reported here to fabricate graphene oxide-immobilized NH2-terminated silicon nanoparticles (NPs) negative electrode (Si@NH2/GO) directed by hydrogen bonding and cross-linked interactions to enhance the capacity retention of the anode. The NH2-modified Si NPs first form strong hydrogen bonds and covalent bonds with GO. The Si@NH2/GO composite further forms hydrogen bonds and covalent bonds with sodium alginate, which acts as a binder, to yield a stable composite negative electrode. These two chemical cross-linked/hydrogen bonding interactions-one between NH2-modified Si NPs and GO, and another between the GO and sodium alginate-along with highly mechanically flexible graphene oxide, produced a robust network in the negative electrode system to stabilize the electrode during discharge and charge cycles. The as-prepared Si@NH2/GO electrode exhibits an outstanding capacity retention capability and good rate performance, delivering a reversible capacity of 1000 mAh g(-1) after 400 cycles at a current of 420 mA g(-1) with almost 100% capacity retention. The results indicated the importance of system-level strategy for fabricating stable electrodes with improved electrochemical performance. PMID:24922522

Sun, Cheng; Deng, Yuanfu; Wan, Lina; Qin, Xusong; Chen, Guohua

2014-07-23

227

Influence of interlayer trapping and detrapping mechanisms on the electrical characterization of hafnium oxide/silicon nitride stacks on silicon  

SciTech Connect

Al/HfO{sub 2}/SiN{sub x}:H/n-Si metal-insulator-semiconductor capacitors have been studied by electrical characterization. Films of silicon nitride were directly grown on n-type silicon substrates by electron cyclotron resonance assisted chemical vapor deposition. Silicon nitride thickness was varied from 3 to 6.6 nm. Afterwards, 12 nm thick hafnium oxide films were deposited by the high-pressure sputtering approach. Interface quality was determined by using current-voltage, capacitance-voltage, deep-level transient spectroscopy (DLTS), conductance transients, and flatband voltage transient techniques. Leakage currents followed the Poole-Frenkel emission model in all cases. According to the simultaneous measurement of the high and low frequency capacitance voltage curves, the interface trap density obtained for all the samples is in the 10{sup 11} cm{sup -2} eV{sup -1} range. However, a significant increase in this density of about two orders of magnitude was obtained by DLTS for the thinnest silicon nitride interfacial layers. In this work we probe that this increase is an artifact that must be attributed to traps existing at the HfO{sub 2}/SiN{sub x}:H intralayer interface. These traps are more easily charged or discharged as this interface comes near to the substrate, that is, as thinner the SiN{sub x}:H interface layer is. The trapping/detrapping mechanism increases the capacitance transient and, in consequence, the DLTS measurements have contributions not only from the insulator/substrate interface but also from the HfO{sub 2}/SiN{sub x}:H intralayer interface.

Garcia, H.; Duenas, S.; Castan, H.; Gomez, A.; Bailon, L. [Departamento de Electricidad y Electronica, E.T.S.I. Telecomunicacion, Universidad de Valladolid, Campus 'Miguel Delibes', 47011 Valladolid (Spain); Toledano-Luque, M.; Prado, A. del; Martil, I.; Gonzalez-Diaz, G. [Departamento de Fisica Aplicada III (Electricidad y Electronica), Facultad de Ciencias Fisicas, Universidad Complutense, 28040 Madrid (Spain)

2008-11-01

228

Screening of transition and post-transition metals to incorporate into copper oxide and copper bismuth oxide for photoelectrochemical hydrogen evolution.  

PubMed

A new dispenser and scanner system is used to create and screen Bi-M-Cu oxide arrays for cathodic photoactivity, where M represents 1 of 22 different transition and post-transition metals. Over 3000 unique Bi?:?M?:?Cu atomic ratios are screened. Of the 22 metals tested, 10 show a M-Cu oxide with higher photoactivity than CuO and 10 show a Bi-M-Cu oxide with higher photoactivity than CuBi2O4. Cd, Zn, Sn, and Co produce the most photoactive M-Cu oxides, all showing a 200-300% improvement in photocurrent over CuO. Ag, Cd, and Zn produce the highest photoactivity Bi-M-Cu oxides with a 200-400% improvement over CuBi2O4. Most notable is a Bi-Ag-Cu oxide (Bi?:?Ag?:?Cu atomic ratio of 22?:?3?:?11) which shows 4 times higher photocurrent than CuBi2O4. This material is capable of evolving hydrogen under illumination in neutral electrolyte solutions at 0.6 V vs. RHE when Pt is added to the surface as an electrocatalyst. PMID:23420023

Berglund, Sean P; Lee, Heung Chan; Núñez, Paul D; Bard, Allen J; Mullins, C Buddie

2013-04-01

229

Metal and organic contamination effects on the characteristics of thin oxides thermally grown on silicon based wafers  

NASA Astrophysics Data System (ADS)

The control of silicon dioxide properties in ULSI applications is important due to the trend in reducing the oxide thickness. The degree of residual contamination of silicon substrate can become a relevant component for the integrity and quality of thin and very thin oxides. This paper investigates the influence that metallic and organic contaminants can have on growth rate, dielectric strength and charges in thin and very thin oxides thermally grown on silicon wafers by various oxidation processes that led to oxide thickness values in the range of 3-30 nm. The effect of alkali metals (K, Ca, Na), fast diffusing metals (Ni, Cu) and caprolactam (as an example of organic contaminant) has been evaluated with a variety of techniques: ellipsometry for oxide thickness measurement, ICP-MS for determination of metal concentration in the oxide, gate oxide integrity, triangular voltage sweep and advanced Elymat technique. The paper provides a useful quantification of the relationship between alkali metal contamination and oxide growth rate, insights on the segregation of fast diffuser metals in silicon dioxide and their effect on oxide integrity, preliminary evaluation of organic contamination effect on oxide interface states and oxide integrity.

Borionetti, G.; Geranzani, P.; Orizio, R.; Godio, P.; Bonoli, F.; Pagani, F.; Pello', C.

2006-12-01

230

Oxidation of tin on silicon substrate by rapid isothermal processing  

NASA Astrophysics Data System (ADS)

We report an oxidation study of an Sn overlayer on Si(100) carried out at 400 °C by rapid isothermal processing (RIP) and furnace processing. Single oxide phase SnO2 could be obtained only by rapid isothermal processing. Based on x-ray diffraction, x-ray photoelectron spectroscopy, high-frequency capacitance-voltage characteristics, and breakdown measurements, improved quality of dielectric films was obtained by RIP. A possible explanation based on the difference in the radiation spectrum of the two sources of energy is also given.

Singh, R.; Chou, P.; Radpour, F.; Nelson, A. J.; Ullal, H. S.

1989-09-01

231

Characterization of oxide scales thermally formed on single-crystal silicon carbide.  

PubMed

Microstructures of oxide scales thermally formed on single-crystal silicon carbide were investigated using transmission electron microscopy. The oxide scales were formed on the Si-face of 6H-SiC at 1273-1473 K in dry oxygen. Spherical patterns were observed on the surfaces of the oxidized samples by an optical microscope in some regions. In these regions, cross-sectional transmission electron microscopy (TEM) observations show that the oxide scale was divided into two layers; the upper layer (surface side) was composed of crystalline silica, and the lower layer on the silicon carbide substrate was amorphous silica, while the oxide scales in the surroundings of the patterns were composed of only amorphous silica. The oxidation activation energy in the amorphous silica layer of the Si-face of 6H-SiC was found to be 408 kJ/mol by the evolution of thickness directly measured from the cross-sectional scanning electron microscopy and TEM images. PMID:20554755

Chayasombat, B; Kato, T; Hirayama, T; Tokunaga, T; Sasaki, K; Kuroda, K

2010-08-01

232

Effect of W and WC on the oxidation resistance of yttria-doped silicon nitride  

NASA Technical Reports Server (NTRS)

The effect of tungsten and tungsten carbide contamination on the oxidation and cracking in air of yttria-doped silicon nitride ceramics is investigated. Silicon nitride powder containing 8 wt % Y2O3 was doped with 2 wt % W, 4 wt % W, 2 wt % WC or left undoped, and sintered in order to simulate contamination during milling, and specimens were exposed in air to 500, 750 and 1350 C for various lengths of time. Scanning electron and optical microscopy and X-ray diffraction of the specimens in the as-sintered state reveals that the addition of W or WC does not affect the phase relationships in the system, composed of alpha and beta Si3N4, melilite and an amorphous phase. Catastrophic oxidation is observed at 750 C in specimens containing 2 and 4 wt % W, accompanied by the disappearance of alpha Si3N4 and melilite from the structure. At 1350 C, the formation of a protective glassy oxide layer was observed on all specimens without catastrophic oxidation, and it is found that pre-oxidation at 1350 C also improved the oxidation resistance at 750 C of bars doped with 4 wt % W. It is suggested that tungsten contamination from WC grinding balls may be the major cause of the intermediate-temperature cracking and instability frequently observed in Si3N4-8Y2O3.

Schuon, S.

1980-01-01

233

The growth of microcrystalline silicon oxide thin films studied by in situ plasma diagnostics  

NASA Astrophysics Data System (ADS)

The crystallinity and refractive index of microcrystalline silicon oxide (?c-SiOx:H) n-layers and their dependence on the pressure and radio frequency power during the deposition process is correlated with plasma properties derived from in situ diagnostics. From process gas depletion measurements, the oxygen content of the layers was calculated. High crystallinities were observed for increased pressures and decreased powers, indicating clear differences to trends previously shown for microcrystalline silicon (?c-Si:H) material, which are explained by the varying oxygen incorporation. Amorphous/microcrystalline silicon (a-Si:H/?c-Si:H) tandem solar cells with ?c-SiOx:H intermediate reflector layers deposited at optimized pressures showed greatly improved series resistances.

Kirner, S.; Gabriel, O.; Stannowski, B.; Rech, B.; Schlatmann, R.

2013-02-01

234

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof  

DOEpatents

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications is disclosed. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al[sub x]N[sub y]O[sub z] layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al[sub x]N[sub y]O[sub z] layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Sarin, V.K.

1990-08-21

235

Oxidation resistant high temperature thermal cycling resistant coatings on silicon-based substrates and process for the production thereof  

DOEpatents

An oxidation resistant, high temperature thermal cycling resistant coated ceramic article for ceramic heat engine applications. The substrate is a silicon-based material, i.e. a silicon nitride- or silicon carbide-based monolithic or composite material. The coating is a graded coating of at least two layers: an intermediate AlN or Al.sub.x N.sub.y O.sub.z layer and an aluminum oxide or zirconium oxide outer layer. The composition of the coating changes gradually from that of the substrate to that of the AlN or Al.sub.x N.sub.y O.sub.z layer and further to the composition of the aluminum oxide or zirconium oxide outer layer. Other layers may be deposited over the aluminum oxide layer. A CVD process for depositing the graded coating on the substrate is also disclosed.

Sarin, Vinod K. (Lexington, MA)

1990-01-01

236

Size-dependent elastic properties of oxidized silicon nanorods  

NASA Astrophysics Data System (ADS)

In this work, we have simulated a three point bending test for Si nanorods of different sizes with an oxide coating of different thicknesses using molecular dynamics simulations and the finite element modeling (FEM). We tested nanorods with diameters from 6 to 16 nm, which had lengths from 31 to 62 nm. Our aim was to estimate how well the elastic properties of Si nanorods can be described using the classical continuum mechanics approach. The agreement between the MD simulations and the FEM calculations was consistent for the pristine Si nanorods of all sizes, whereas the oxidized Si nanorods with small length-to-diameter ratio had much smaller effective bending moduli values than predicted by FEM. Our assumption is that it is due to the significant decrease of the shear modulus in the oxide layer of the smallest nanorods. We had also introduced surface stresses into the FEM models and found that their influence on the bending properties is more important for partially oxidized nanorods.

Ilinov, Andrey; Kuronen, Antti

2014-11-01

237

Quantum Conductance in Silicon Oxide Resistive Memory Devices  

PubMed Central

Resistive switching offers a promising route to universal electronic memory, potentially replacing current technologies that are approaching their fundamental limits. In many cases switching originates from the reversible formation and dissolution of nanometre-scale conductive filaments, which constrain the motion of electrons, leading to the quantisation of device conductance into multiples of the fundamental unit of conductance, G0. Such quantum effects appear when the constriction diameter approaches the Fermi wavelength of the electron in the medium – typically several nanometres. Here we find that the conductance of silicon-rich silica (SiOx) resistive switches is quantised in half-integer multiples of G0. In contrast to other resistive switching systems this quantisation is intrinsic to SiOx, and is not due to drift of metallic ions. Half-integer quantisation is explained in terms of the filament structure and formation mechanism, which allows us to distinguish between systems that exhibit integer and half-integer quantisation. PMID:24048282

Mehonic, A.; Vrajitoarea, A.; Cueff, S.; Hudziak, S.; Howe, H.; Labbé, C.; Rizk, R.; Pepper, M.; Kenyon, A. J.

2013-01-01

238

Silicon-oxide-assisted wear of a diamond-containing composite  

NASA Astrophysics Data System (ADS)

A composite containing diamond in silicon carbide substrate was studied for revealing wear mechanisms. Due to the low production cost, this material is being evaluated as an alternative economical solution in industry. Tribochemical examination was conducted using a pin-on-disk configuration in both aqueous and dry environments. Characterization was conducted on worn disks and wear debris. Phase transformation from diamond carbon (sp3) to graphite, tetrahedral carbon, or amorphous carbon (sp2) in friction was confirmed by Raman spectroscopy. In addition, the Raman peak of wear debris identified a shift from crystalline Si (521 cm-1) to the mixture of amorphous silicon and silicon oxide at 510 cm-1. The surface roughness of the diamond particles was found to be greatly reduced due to wear. The smoothening of the edges was due to polishing by silicon oxide as abrasives promoting removal of weaker sp2 bonded carbon. This research proposes a tribochemical wear mechanism of diamond that has significant benefits in the applications of automotive, aerospace, and energy industries.

Xiao, Huaping; Sinyukov, Alexander M.; He, Xingliang; Lin, Chih; Liang, Hong

2013-12-01

239

Novel Iron-oxide Catalyzed CNT Formation on Semiconductor Silicon Nanowire.  

PubMed

An aqueous ferric nitrate nonahydrate (Fe(NO3)3.9H2O) and magnesium oxide (MgO) were mixed and deposited on silicon nanowires (SiNWs), the carbon nanotubes (CNTs) formed by the concentration of Fe3O4/MgO catalysts with the mole ratio set at 0.15:9.85 and 600°C had diameter between 15.23 to 90nm with high-density distribution of CNT while those with the mole ratio set at 0.45:9.55 and 730°C had diameter of 100 to 230nm. The UV/Vis/NIR and FT-IR spectroscopes clearly confirmed the presence of the silicon-CNTs hybrid structure. UV/Vis/NIR, FT-IR spectra and FESEM images confirmed the silicon-CNT structure exists with diameters ranging between 15-230nm. Thus, the study demonstrated cost effective method of silicon-CNT composite nanowire formation via Iron-oxide Catalyze synthesis. PMID:25237290

Adam, Tijjani; U, Hashim

2014-10-01

240

An interface state mediated junction leakage mechanism induced by a single polyhedral oxide precipitate in silicon diode  

Microsoft Academic Search

The impact of an oxide precipitate on the junction leakage of a silicon p\\/n diode was investigated. A 70-100 nm diam single polyhedral oxide precipitate was placed in the depletion region of a p+\\/n junction by hydrogen annealing and polishing a Czochralski grown silicon wafer. In the reverse-bias current-voltage (I-V) curve, an anomalous hump structure was observed. This excess leakage

M. Tsuchiaki; H. Fujimori; T. Iinuma; A. Kawasaki

1999-01-01

241

Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide synthesis and detection  

PubMed Central

Direct solid phase synthesis of peptides and oligonucleotides (ONs) requires high chemical stability of the support material. In this work, we have investigated the passivation ability of porous oxidized silicon multilayered structures by two aminosilane compounds, 3-aminopropyltriethoxysilane and 3-aminopropyldimethylethoxysilane (APDMES), for optical label-free ON biosensor fabrication. We have also studied by spectroscopic reflectometry the hybridization between a 13 bases ON, directly grown on the aminosilane modified porous oxidized silicon by in situ synthesis, and its complementary sequence. Even if the results show that both devices are stable to the chemicals (carbonate/methanol) used, the porous silica structure passivated by APDMES reveals higher functionalization degree due to less steric hindrance of pores. PMID:23536541

De Stefano, Luca; Oliviero, Giorgia; Amato, Jussara; Borbone, Nicola; Piccialli, Gennaro; Mayol, Luciano; Rendina, Ivo; Terracciano, Monica; Rea, Ilaria

2013-01-01

242

Effect of Alcohol-Assisted Annealing on the Quality of Silicon Oxide Thin Film  

NASA Astrophysics Data System (ADS)

Silicon oxide thin films have been formed by use of the reaction between spin-coated silicone oil and ozone gas at atmospheric pressure and low temperature (250°C). Films formed at this temperature contained Si-OH bonds, owing to inadequate dehydration. To remove the Si-OH bonds at low temperature, the sample was dipped in ethanol at room temperature for 15 min then annealed on a hot plate at 250°C in methanol gas for 30 min. This treatment effectively dissociated the Si-OH bonds. It is believed the Si-OH bonds are replaced by Si-OCH3 bonds during the alcohol-assisted annealing. The leakage current of the metal-oxide-semiconductor after alcohol-assisted annealing was improved and the hysteresis width was reduced. This indicated that the number of trap sites owing to Si-OH bonds was reduced.

Ito, Takuya; Ota, Yasuyuki; Shiomori, Koichiro; Nishioka, Kensuke

2014-07-01

243

Determination of Mean Thickness of an Oxide Layer on a Silicon Sphere by Spectroscopic Ellipsometry  

NASA Astrophysics Data System (ADS)

One of the biggest obstacles to reduce the uncertainty of the Avogadro constant NA is such that there will be an oxide layers on the surface of a silicon sphere. The thickness of this layer is measured by a modified spectroscopic ellipsometer, which can eliminate the influence of the curved surface, and the results are calibrated by x-ray reflectivity. Fifty positions distributed nearly uniformly on the surface of the silicon sphere are measured twice. The results show that the mean thickness of the overall oxide layer is 3.75 nm with the standard uncertainty of 0.21 nm, which means that the relative uncertainty component of NA owing to this layer can be reduced to 1.2 × 10-8.

Zhang, Ji-Tao; Li, Yan; Luo, Zhi-Yong; Wu, Xue-Jian

2010-05-01

244

The influence of hydrogen on the growth of gallium catalyzed silicon oxide nanowires  

NASA Astrophysics Data System (ADS)

In this paper, we report that amorphous silicon oxide nanowires can be grown in a large quantity by chemical vapor deposition with molten gallium as the catalyst in a flow of mixture of SiH4, H2 and N2 at 600 °C. Meanwhile, when we grow these nanowires under the same conditions but without H2, octopus-like silicon oxide nanostructures are obtained. The reasons and mechanisms for the growth of these nanowires and nanostructures are discussed. Blue light emission is observed from SiOx nanowires, which can be attributed to defect centers of high oxygen deficiency. These SiOx nanowires may find applications in nanodevices and reinforcing composites.

Yan, X. Q.; Zhou, W. Y.; Sun, L. F.; Gao, Y.; Liu, D. F.; Wang, J. X.; Zhou, Z. P.; Yuan, H. J.; Song, L.; Liu, L. F.; Wang, G.; Xie, S. S.

2005-05-01

245

Three-dimensional design and replication of silicon oxide nanostructures using an atomic force microscope  

NASA Astrophysics Data System (ADS)

Atomic force microscope (AFM) based local anodic oxidation of metallic and semiconducting layers has emerged as a powerful tool for nanoscale fabrication. A unique nanoscale patterning technique has been created that couples computer aided design (CAD) with the lithographic capabilities of the AFM. Target nanostructures to be deposited on a silicon substrate are rendered as a three-dimensional model. Using AFM based local anodic oxidation on a silicon substrate, the features are duplicated at the nanoscale using voltage bias, probe speed, and humidity modulation, as prescribed by the model. The work presented herein highlights the advantages when three-dimensional modeling is linked with nanolithography; nanoscale features can be precisely replicated from a design plan.

Johannes, Matthew S.; Cole, Daniel G.; Clark, Robert L.

2007-08-01

246

Complete coverage of reduced graphene oxide on silicon dioxide substrates  

NASA Astrophysics Data System (ADS)

Reduced graphene oxide (RGO) has the advantage of an aqueous and industrial-scale production route. No other approaches can rival the RGO field effect transistor platform in terms of cost (oxide with ethanol, carbon islets are deposited preferentially at the edges of existing flakes. With a 2-h treatment, the standard deviation in electrical resistance of the treated chips can be reduced by 99.95%. Thus this process could enable RGO to be used in practical electronic devices.

Huang, Jingfeng; Melanie, Larisika; Chen, Hu; Steve, Faulkner; Myra, A. Nimmo; Christoph, Nowak; Alfred Tok Iing, Yoong

2014-08-01

247

Mechanical anomaly impact on metal-oxide-semiconductor capacitors on flexible silicon fabric  

NASA Astrophysics Data System (ADS)

We report the impact of mechanical anomaly on high-?/metal-oxide-semiconductor capacitors built on flexible silicon (100) fabric. The mechanical tests include studying the effect of bending radius up to 5 mm minimum bending radius with respect to breakdown voltage and leakage current of the devices. We also report the effect of continuous mechanical stress on the breakdown voltage over extended periods of times.

Ghoneim, M. T.; Kutbee, A.; Ghodsi Nasseri, F.; Bersuker, G.; Hussain, M. M.

2014-06-01

248

Ultrathin high-K metal oxides on silicon: processing, characterization and integration issues  

Microsoft Academic Search

An overview of our recent work on ultrathin (<100 Å) films of metal oxides deposited on silicon for advanced gate dielectrics applications will be presented. Data on ultrathin Al2O3, ZrO2, HfO2, and Y2O3 will be shown to illustrate the complex processing, integration and device-related issues for high dielectric constant (‘high-K’) materials. Both physical and electrical properties, as well as the

E. P Gusev; E Cartier; D. A Buchanan; M Gribelyuk; M Copel; H Okorn-Schmidt; C D’Emic

2001-01-01

249

Electron stimulated oxidation and rhenium electrical contacts on alpha-silicon carbide  

Microsoft Academic Search

Electron stimulated oxidation (ESO) and rhenium (Re) metallizations on alpha-silicon carbide (6H-SiC) were studied. ESO was quantified versus electron beam exposure, total vacuum pressure, beam energy Ep (3 to 6 keV), and current Ip (25 to 500 nA), while monitoring chemical change using Auger electron spectroscopy (AES). Vacuum chamber pressures below 2.6 x 10 -8 Torr required beam irradiation to

Gavin Young McDaniel

2002-01-01

250

Silicon-riched-oxide cluster assembled nanostructures formed by low energy cluster beam deposition  

Microsoft Academic Search

Free beam of silicon oxide nanoclusters is produced by a gas aggregation source from SiO precursor. Due to the disproportionation reaction during the condensation of SiO vapor the generated clusters are Si-riched. The clusters are collimated to be a fine beam and deposited on the substrate at room temperature. The microstructures of the cluster-based nanofilm are characterized by TEM. It

M. Han; J. F. Zhou; F. Q. Song; C. R. Yin; M. D. Liu; J. G. Wan; G. H. Wang

2003-01-01

251

Enhancement of oxidation resistance of NBD 200 silicon nitride ceramics by aluminum implantation  

Microsoft Academic Search

Silicon nitride (Si3N4) ceramics are leading candidates for high temperature structural applications. They have already demonstrated functional capabilities well beyond the limits of conventional metals and alloys in advanced diesel and turbine engines. However, the practical exploitation of these benefits is limited by their oxidation and associated degradation processes in chemically aggressive environments. Additives and impurities in Si3N4 segregate to

Priya Mukundhan

2000-01-01

252

Oxidation of hydrogen doped tantalum films on silicon  

SciTech Connect

Hydrogen doping of Ta films before thermal oxidation affects the dc leakage current in oxidized Ta films. Metal-insulator-semiconductor (MIS) capacitors of Al/Ta/sub 2/O/sub 5/ (40 nm thick)/Si-substrate structures have been prepared for the electrical measurements. The Ta films were reactively sputtered on p-type Si substrates in a mixture of Ar and H/sub 2/ gases suitable for hydrogen doping. The hydrogen doping was found to be effective in reducing the leakage current in the Ta/sub 2/O/sub 5/ films to be less than 10/sup -3/ times that of undoped films, especially after low temperature oxidation at 400 /sup 0/C. Secondary ion mass spectrometry (SIMS) analysis showed that the incorporation in the Ta/sub 2/O/sub 5/ films of Si from the substrate was decreased by the presence of hydrogen during sputtering. A possible explanation for the reduction of leakage current caused by hydrogen doping is that the prevention of Si entry into Ta/sub 2/O/sub 5/ films reduces the density of oxygen vacancies induced by unsaturated SiO/sub x/(x<2). This is thought to suppress the Poole--Frenkel-type conduction in the Ta/sub 2/O/sub 5/ films.

Ohfuji, S.; Hashimoto, C.

1986-05-01

253

Magnetometer uses bismuth-selenide  

NASA Technical Reports Server (NTRS)

Characteristics of bismuth-selenide magnetometer are described. Advantages of bismuth-selenide magnetometer over standard magnetometers are stressed. Thermal stability of bismuth-selenide magnetometer is analyzed. Linearity of output versus magnetic field over wide range of temperatures is reported.

Woollman, J. A.; Spain, I. L.; Beale, H.

1972-01-01

254

Formation and passivation of new paramagnetic defects associated with thermal oxides on silicon  

NASA Astrophysics Data System (ADS)

A new spin resonance spectrum has been observed with electron paramagnetic resonance in thermal oxides grown on (111) silicon. Our analysis indicates that this new spectrum consists of two isotropic resonances. One resonance has a g-value of 2.0026 and a linewidth (FWHM) of 1.2 G (labeled SL8); the other resonance has a g-value of 2.0029 and a linewidth (FWHM) of 5 G (labeled SL9). The SL8 resonance appears to be associated with the as-grown thermal oxide. The effects of Co-60 gamma irradiation and annealing in either hydrogen or ammonia on these spectra are also presented.

Brower, K. L.

255

Patterns of discoloration and oxidation by direct and scattered fluxes, especially oxygen on silicon  

NASA Technical Reports Server (NTRS)

A number of interesting discoloration patterns are clearly evident on M0002-1 which resides on three faces of LDEF: front face, rear face, and earth face. Most interesting is the pattern of blue oxidation on polished single crystal silicon apparently produced by once-scattered ram oxygen atoms along the earth face. Most of the other patterns are seen in the Thermal Control Paint. Also, severe oxidation of CR-39 polycarbonate occurred on the front face of LDEF, as expected. A complete explanation for the patterns has not yet been obtained.

Frederickson, A. R.; Filz, R. C.; Rich, F. J.; Sagalyn, Paul L.

1991-01-01

256

Detection of an Oxygen-Excessive Layer in Thermally Grown Silicon Oxide  

NASA Astrophysics Data System (ADS)

This paper describes depth profiling of the oxygen (O) content of thermally grown silicon oxide by Auger electron spectroscopy (AES). In this approach, the Auger peak area value obtained by integrating the first-derivative spectrum is used as the signal intensity. After profiling of a number of similar samples, the average values of signal intensities for the same depths are plotted to obtain smooth profiles. The O signal intensities are higher in the oxide/substrate interface region than the bulk oxide region. X-ray photoelectron spectroscopy (XPS) profiling confirms an increase in O signal intensity in the same region. This region approximately corresponds to a structural transition layer of a newly formed oxide.

Watanabe, Yoshio

1995-09-01

257

Erbium Silicon Oxide crystalline films prepared by MOMBE  

NASA Astrophysics Data System (ADS)

Er-Si-O crystalline thin film preparation on silicon substrates by using metal organic molecular beam epitaxy (MOMBE) is proposed. Tetra ethoxy silane (TEOS) and tris-2,2,6,6-tetra methyl-3,5-octane dionato erbium (Er(TMOD) 3) were used as Si-O and Er-O precursors, respectively. The Er-Si-O thin film crystallizes mainly during the post-annealing process and into a novel type of erbium-silicate crystalline compounds, which have not ever been reported. The atomic fraction of Er:Si:O in the prepared thin film is 3:2:8. The Er 3+ related PL spectra show a fine structure with a line width of less than 1 meV at 20 K and 4 meV at room temperature. The narrow line width is due to the crystalline nature. In addition, the PL spectrum fine structure observed in these Er-Si-O films has reproduced the fine structure observed in Er-Si-O crystallites prepared by the wet-chemical method reported by Isshiki et al. The present results have proved that the method proposed in this paper is effective to form Er-Si-O crystalline films.

Masaki, K.; Isshiki, H.; Kimura, T.

2005-02-01

258

Effect of ion-plated films of germanium and silicon on friction, wear, and oxidation of 52100 bearing steel  

NASA Technical Reports Server (NTRS)

Friction and wear experiments were conducted with ion plated films of germanium and silicon on the surface of 52100 bearing steel both dry and in the presence of mineral oil. Both silicon and germanium were found to reduce wear, with germanium being more effective than silicon. An optimum film thickness of germanium for minimum wear without surface crack formation was found to be approximately 400 nanometers (4000 A). The presence of silicon and germanium on the 52100 bearing steel surface improved resistance to oxidation.

Buckley, D. H.; Spalvins, T.

1977-01-01

259

Hydrothermal synthesis map of bismuth titanates  

SciTech Connect

The hydrothermal synthesis of four bismuth titanate materials from common bismuth and titanium precursors under hydrothermal conditions is described. Reaction of NaBiO{sub 3}{center_dot}2H{sub 2}O and anatase TiO{sub 2} in concentrated NaOH solution at 240 Degree-Sign C is shown to produce perovskite and sillenite phases Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} and Bi{sub 12}TiO{sub 20}, depending on the ratio of metal precursors used. When KOH solution is used and a 1:1 ratio of the same precursors, a pyrochlore Bi{sub 1.43}Ti{sub 2}O{sub 6}(OH){sub 0.29}(H{sub 2}O){sub 0.66} is formed. The use of a mixture of HNO{sub 3} and NaOH is shown to facilitate the formation of the Aurivillius-type bismuth titanate Bi{sub 4}Ti{sub 3}O{sub 12}. The phases have been isolated separately as phase-pure powders and profile refinement of powder X-ray diffraction data allows comparisons with comparable materials reported in the literature. Analysis of Bi L{sub III}-edge X-ray absorption near edge structure (XANES) spectra of the materials shows the oxidation state of bismuth is +3 in all of the hydrothermally derived products. - Graphical abstract: Use of NaBiO{sub 3}{center_dot}2H{sub 2}O and TiO{sub 2} as reagents under hydrothermal conditions allows the phase-pure preparation of four crystalline bismuth titanate materials. Highlights: Black-Right-Pointing-Pointer NaBiO{sub 3} and TiO{sub 2} under hydrothermal conditions allow formation of bismuth titanates. Black-Right-Pointing-Pointer Synthesis of four distint phases has been mapped. Black-Right-Pointing-Pointer Bi LIII-edge XANES shows Bi is reduced to oxidation state +3 in all materials. Black-Right-Pointing-Pointer A new hydrated bismuth titanate pyrochlore has been isolated.

Sardar, Kripasindhu [Department of Chemistry, University of Warwick, Coventry, CV4 7AL (United Kingdom); Walton, Richard I., E-mail: r.i.walton@warwick.ac.uk [Department of Chemistry, University of Warwick, Coventry, CV4 7AL (United Kingdom)

2012-05-15

260

Bismuth glass holey fibers with high nonlinearity  

Microsoft Academic Search

We report on the progress of bismuth oxide glass holey fibers for nonlinear device applications. The use of micron-scale core diameters has resulted in a very high nonlinearity of 1100 W-1 km-1 at 1550 nm. The nonlinear performance of the fibers is evaluated in terms of a newly introduced figure-of-merit for nonlinear device applications. Anomalous dispersion at 1550 nm has

Heike Ebendorff-Heidepriem; P. Petropoulos; S. Asimakis; V. Finazzi; R. C. Moore; K. Frampton; F. Koizumi; D. J. Richardson; T. M. Monro

2004-01-01

261

Oxidation of chemically-vapor-deposited silicon nitride and single-crystal silicon  

NASA Technical Reports Server (NTRS)

The present 1000 C and 1300 C oxidation tests on 111-oriented single-crystal Si and dense CVD Si3N4 notes the oxidation rates of the latter in wet O2, dry O2, wet inert gas, and steam atmosphere conditions to be several orders of magnitude lower than the rates for the former in identical atmospheric conditions. Although the parabolic rate constant for Si increased linearly as the water vapor pressure increased, the parabolic rate constant for Si3N4 exhibited a nonlinear dependency on water vapor pressure in the presence of O2. NO and NH3 formation at the reaction interface of Si3N4, and the counterpermeation of these reaction products, are noted to dominate reaction kinetics.

Choi, Doo J.; Fischbach, David B.; Scott, William D.

1989-01-01

262

Starting Material Silicon substrate  

E-print Network

Starting Material Silicon substrate 150 mm, p-type, , 36-63 ohm-cm Attila Horvath 2005 #12;Pad Oxidation and Nitride Deposition Silicon substrate Pad oxide = 250A Silicon nitride = 2200A Attila Horvath 2005 #12;N-Well Photo and Nitride Etch Silicon substrate Pad oxide Silicon nitride Photo resist Attila

Healy, Kevin Edward

263

Enhanced reduction of silicon oxide thin films on silicon under electron beam annealing  

NASA Astrophysics Data System (ADS)

Electron beam annealing is an interesting alternative to other annealing methods as it can provide high temperature, rapid heating and cooling and low level of impurity as it operates under high vacuum environment. Furthermore swamping the materials with electrons can lead to dramatic changes in the component valence states with the mechanism involving oxido-reduction reactions. This is illustrated in the present case with the enhancement of the reduction of SiO2. Commercial thermally grown 100 and 400 nm SiO2 films on Si were annealed under three different environments: furnace annealing in open atmosphere with O2 flow, high vacuum furnace annealing and electron beam annealing. The reduction and oxidation of SiO2 films on Si are investigated using ion beam analysis. The validity of the measurement method was confirmed by measuring the oxidation rate through successive Rutherford backscattering spectrometry (RBS) measurements. The oxidation kinetics were observed to be in excellent agreement with literature values. At 1000 °C reduction of the SiO2 film is observed only with electron beam annealing. A model is proposed to explain the effect of the electron beam.

Kennedy, J.; Leveneur, J.; Fang, F.; Markwitz, A.

2014-08-01

264

Oxidation of the porous silicon surface under the action of a pulsed ionic beam: XPS and XANES studies  

NASA Astrophysics Data System (ADS)

The changes in the electronic structure and phase composition of porous silicon under action of pulsed ionic beams have been studied by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge spectroscopy (XANES) using synchrotron radiation. The Si 2 p and O 1 s core photoemission spectra for different photoelectron collection angles, valence band photoemission spectra, and X-ray absorption near-edge fine structure spectrain the region of Si L 2,3 edges of the initial and irradiated samples have been analyzed. It has been found that, as a result of the irradiation, a thin oxide film consisting predominantly of higher oxide SiO2 is formed on the porous silicon surface, which increases the energy gap of the silicon oxide. Such film exhibits passivation properties preventing the degradation of the composition and properties of porous silicon in contact with the environment.

Bolotov, V. V.; Ivlev, K. E.; Korusenko, P. M.; Nesov, S. N.; Povoroznyuk, S. N.

2014-06-01

265

Effect of nitric oxide annealing on the interface trap densities near the band edges in the 4H polytype of silicon carbide  

E-print Network

polytype of silicon carbide G. Y. Chung, C. C. Tin, and J. R. Williamsa) Physics Department, Auburn­voltage measurements are reported for metal­oxide­semiconductor capacitors fabricated using the 4H polytype of silicon carbide doped with either nitrogen n or aluminum p . Annealing in nitric oxide after a standard oxidation

Pantelides, Sokrates T.

266

Silicon surface deoxidation using strontium oxide deposited with the pulsed laser deposition technique.  

PubMed

The epitaxial growth of functional oxides on silicon substrates requires atomically defined surfaces, which are most effectively prepared using Sr-induced deoxidation. The manipulation of metallic Sr is nevertheless very delicate and requires alternative buffer materials. In the present study the applicability of the chemically much more stable SrO in the process of native-oxide removal and silicon-surface stabilization was investigated using the pulsed-laser deposition technique (PLD), while the as-derived surfaces were analyzed in situ using reflection high-energy electron diffraction and ex situ using X-ray photoelectron spectroscopy, X-ray reflectivity, and atomic force microscopy. After the deposition of the SrO over Si/SiO2, in a vacuum, different annealing conditions, with the temperature ranging up to 850 °C, were applied. Because the deposition took place in a vacuum, a multilayer composed of SrO, Sr-silicate, modified Si, and Si as a substrate was initially formed. During the subsequent annealing the topmost layer epitaxially orders in the form of islands, while a further increase in the annealing temperature induced rapid desorption and surface deoxidation, leading to a 2 × 1 Sr-reconstructed silicon surface. However, the process is accompanied by distinctive surface roughening, and therefore the experimental conditions must be carefully optimized to minimize the effect. The results of the study revealed, for the first time, an effective pathway for the preparation of a SrO-induced buffer layer on a silicon substrate using PLD, which can be subsequently utilized for the epitaxial growth of functional oxides. PMID:25249034

Jovanovi?, Zoran; Spreitzer, Matjaž; Kova?, Janez; Klement, Dejan; Suvorov, Danilo

2014-10-22

267

Photo induced minority carrier annihilation at crystalline silicon surface in metal oxide semiconductor structure  

NASA Astrophysics Data System (ADS)

We report the properties of features of photo induced minority carrier annihilation at the silicon surface in a metal-oxide-semiconductor (MOS) structure using 9.35 GHz microwave transmittance measurement. 7 ? cm n-type 500-µm-thick crystalline silicon substrates coated with 100-nm-thick thermally grown SiO2 layers were prepared. Part of the SiO2 at the rear surface was removed. Al electrode bars were formed at the top and rear surfaces to form the structures Al/SiO2/Si/SiO2/Al and Al/SiO2/Si/Al. 635 nm light illumination onto the top surface caused photo induced carriers to be in one side of the silicon region of the Al electrode bar of the structure Al/SiO2/Si/SiO2/Al. Microwave transmittance was measured on the other side of the silicon region of the Al electrode bars. The measurement and analysis of microwave absorption by photo induced carriers laterally diffusing across the silicon region coated with Al electrodes revealed a change in the carrier recombination velocity at the silicon surface with the bias voltage applied onto the top Al electrode. The applied bias voltages of +2.0 and -2.2 V gave peaks at surface recombination velocities of 83 and 86 cm/s, respectively, for the sample structure Al/SiO2/Si/SiO2/Al, while it was 44 cm/s under the bias-free condition. A peak surface recombination velocity of 81 cm/s was only observed at a bias voltage of -2.0 V for the sample structure Al/SiO2/Si/Al.

Sameshima, Toshiyuki; Furukawa, Jun; Nakamura, Tomohiko; Shigeno, Satoshi; Node, Tomohito; Yoshidomi, Shinya; Hasumi, Masahiko

2014-03-01

268

Structural silicon nitride materials containing rare earth oxides  

DOEpatents

A ceramic composition suitable for use as a high-temperature structural material, particularly for use in apparatus exposed to oxidizing atmospheres at temperatures of 400 to 1600.degree. C., is found within the triangular area ABCA of the Si.sub.3 N.sub.4 --SiO.sub.2 --M.sub.2 O.sub.3 ternary diagram depicted in FIG. 1. M is selected from the group of Yb, Dy, Er, Sc, and alloys having Yb, Y, Er, or Dy as one component and Sc, Al, Cr, Ti, (Mg +Zr) or (Ni+Zr) as a second component, said alloy having an effective ionic radius less than 0.89 A.

Andersson, Clarence A. (Pittsburgh, PA)

1980-01-01

269

Sintering of silicon nitride ceramics with magnesium silicon nitride and yttrium oxide as sintering aids  

NASA Astrophysics Data System (ADS)

Silicon nitride (Si3N4) ceramics had been produced through pressureless sintering and hot-pressing sintering with MgSiN2-Y2O3 or only MgSiN2 as sintering aids. The influences of the amount of MgSiN2 and Y2O3 and sintering methods on the properties of Si3N4 ceramics were investigated. The results show that the bend strength of Si3N4 ceramic fabricated through pressureless sintering at 1820 °C for 4 h with 5.6 wt.% MgSiN2-15.8 wt.% Y2O3 as sintering additive could achieve 839 MPa. However, the bend strength of Si3N4 ceramic produced by hot-pressing sintering at 1750 °C for 1 h under uniaxial pressure of 20 MPa with 4.76 wt.% MgSiN2 was 1149 MPa. The thermal conductivity of the Si3N4 ceramic 2 3 4 could reach to 129 W·m-1·K1. The present work demonstrated that MgSiN2 aids and hot-pressing sintering were effective to improve the thermal conductivity of Si3N4 ceramic.

Jiang, J.; Xu, J. Y.; Peng, G. H.; Zhuang, H. R.; Li, W. L.; Xu, S. Y.; Mao, Y. J.

2011-10-01

270

Identification and Control of Gravity Related Defect Formation During Melt Growth of Bismuth-Silicate (Bi12SiO20)  

NASA Technical Reports Server (NTRS)

In the light of strong indications that a majority of critical defects formed in bismuth silicon oxide (BSO) during growth from the melt is related directly or indirectly to gravitational interference, it is suggested to use the reduced gravity environment of outer space for experimentation directed at the identification and control of these defects. The results of these experiments are expected to lead to advances in our understanding of crystal growth related defect formation in general and will establish a basis for effective defect engineering, the approach to efficient achievement of defect related, application specific properties in opto-electronic materials

Zheng, Y.; Witt, A. F.

1999-01-01

271

Optimization of oxidation processes to improve crystalline silicon solar cell emitters  

SciTech Connect

Control of the oxidation process is one key issue in producing high-quality emitters for crystalline silicon solar cells. In this paper, the oxidation parameters of pre-oxidation time, oxygen concentration during pre-oxidation and pre-deposition and drive-in time were optimized by using orthogonal experiments. By analyzing experimental measurements of short-circuit current, open circuit voltage, series resistance and solar cell efficiency in solar cells with different sheet resistances which were produced by using different diffusion processes, we inferred that an emitter with a sheet resistance of approximately 70 ?/? performed best under the existing standard solar cell process. Further investigations were conducted on emitters with sheet resistances of approximately 70 ?/? that were obtained from different preparation processes. The results indicate that emitters with surface phosphorus concentrations between 4.96 × 10{sup 20} cm{sup ?3} and 7.78 × 10{sup 20} cm{sup ?3} and with junction depths between 0.46 ?m and 0.55 ?m possessed the best quality. With no extra processing, the final preparation of the crystalline silicon solar cell efficiency can reach 18.41%, which is an increase of 0.4%{sub abs} compared to conventional emitters with 50 ?/? sheet resistance.

Shen, L.; Liang, Z. C., E-mail: liangzc@mail.sysu.edu.cn; Liu, C. F.; Long, T. J.; Wang, D. L. [School of Physics and Engineering, Institute for Solar Energy Systems, Sun Yat-sen University, 510275, Guangzhou (China)] [School of Physics and Engineering, Institute for Solar Energy Systems, Sun Yat-sen University, 510275, Guangzhou (China)

2014-02-15

272

A novel ellipsometer for measuring thickness of oxide layer on the surface of silicon sphere  

NASA Astrophysics Data System (ADS)

The Avogadro constant NA is used as one of the several possible routes to redefinition of the kilogram in metrology today. Usually in order to accurately determine NA, the volume of a perfect single crystal silicon sphere of nearly 1 kg mass should be measured with a high relative uncertainty, i.e. about 1×10 -8. However, the oxide layer grown on the surface of the silicon sphere causes a remarkable systematic difference between the measured and real diameters. A novel ellipsometer has been developed to determine the thickness of the oxide layer accurately and automatically. The arrangement of this instrument is suitable for measuring the layer on the sphere surface. What's more, the measuring is faster by optimizing the parameters and developing the algorithm of calculating the thickness and refractive index of the oxide layer. The preliminary simulation result has present. Thus, the uncertainty of the diameter measurement caused by the oxide layer can be observably reduced. And the further improving of this ellipsometer is discussed in the end.

Zhang, Jitao; Li, Yan

2008-03-01

273

Oxygen permeation in bismuth-based materials part I: Sintering and oxygen permeation fluxes  

E-print Network

1 Oxygen permeation in bismuth-based materials part I: Sintering and oxygen permeation fluxes E;2 Abstract Oxygen permeation measurements were performed on two layered bismuth based oxide ceramics. Oxygen permeability for these systems was compared to permeability of the cubic fluorite type structure

Paris-Sud XI, Université de

274

Gold nanoparticles on oxide-free silicon-molecule interface for single electron transport.  

PubMed

Two different organic monolayers were prepared on silicon Si(111) and modified for attaching gold nanoparticles. The molecules are covalently bound to silicon and form very ordered monolayers sometimes improperly called self-assembled monolayers (SAM). They are designed to be electrically insulating and to have very few electrical interface states. By positioning the tip of an STM above a nanoparticle, a double barrier tunnel junction (DBTJ) is created, and Coulomb blockade is demonstrated at 40 K. This is the first time Coulomb blockade is observed with an organic monolayer on oxide-free silicon. This work focuses on the fabrication and initial electrical characterization of this double barrier tunnel junction. The organic layers were prepared by thermal hydrosilylation of two different alkene molecules with either a long carbon chain (C11) or a shorter one (C7), and both were modified to be amine-terminated. FTIR and XPS measurements confirm that the Si(111) substrate remains unoxidized during the whole chemical process. Colloidal gold nanoparticles were prepared using two methods: either with citrate molecules (Turkevich method) or with ascorbic acid as the surfactant. In both cases AFM and STM images show a well-controlled deposition on the grafted organic monolayer. I-V curves obtained by scanning tunneling spectroscopy (STS) are presented on 8 nm diameter nanoparticles and exhibit the well-known Coulomb staircases at low temperature. The curves are discussed as a function of the organic layer thickness and silicon substrate doping. PMID:23488728

Caillard, Louis; Seitz, Oliver; Campbell, Philip M; Doherty, Rachel P; Lamic-Humblot, Anne-Félicie; Lacaze, Emmanuelle; Chabal, Yves J; Pluchery, Olivier

2013-04-23

275

Effects of inductively coupled plasma oxidation on the properties of polycrystalline silicon films and thin film transistors  

Microsoft Academic Search

We investigated the effects of inductively coupled plasma (ICP) oxidation on the properties of polycrystalline silicon (poly-Si) films and thin film transistors (TFTs). The ICP oxidation in oxygen plasma passivated the dangling bonds in the poly-Si films, not by oxygen incorporation but by hydrogen incorporation; but the incorporated hydrogen diffused out during the TFT fabrication, so that the effect of

Yong Woo Choi; Sang Won Park; Byung Tae Ahn

1999-01-01

276

Observation of memory effect in germanium nanocrystals embedded in an amorphous silicon oxide matrix of a metalinsulator  

E-print Network

of the memory array. However, such a thick tunnel oxide means that the write and erase pulse durations during-type silicon substrate in dry oxygen ambient using rapid thermal oxidation at 1000 °C. A Ge SiO2 layer

277

Fabrication of piezodriven, free-standing, all-oxide heteroepitaxial cantilevers on silicon  

NASA Astrophysics Data System (ADS)

We report on the fabrication and mechanical properties of all-oxide, free-standing, heteroepitaxial, piezoelectric, microelectromechanical systems (MEMS) on silicon, using PbZr0.52Ti0.48O3 as the key functional material. The fabrication was enabled by the development of an epitaxial lift-off strategy for the patterning of multilayer oxide heterostructures grown on Si(001), employing a high temperature stable, sacrificial oxide template mask to obtain freestanding cantilever MEMS devices after substrate etching. All cantilevers, with lengths in the range 25-325 ?m, width 50 ?m, and total thickness of 300 nm, can be actuated by an external AC-bias. For lengths 50-125 ?m, the second order bending mode formed the dominant resonance, whereas for the other lengths different or multiple modes were present.

Banerjee, N.; Houwman, E. P.; Koster, G.; Rijnders, G.

2014-09-01

278

Electrorheological properties of polyaniline-vanadium oxide nanostructures suspended in silicone oil  

NASA Astrophysics Data System (ADS)

In the present work, organic/inorganic hybrid nanostructures comprised of polyaniline and vanadium oxide were synthesized via a simple hydrothermal technique. The polyaniline/vanadium oxide hybrid morphology was tailored from rods to spheres by controlling the relative concentration of the reactants. The synthesized composites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) for structural and morphological analyses. Electrorheological (ER) properties of the as-prepared nanocomposites suspended in silicone oil were investigated by a rotational viscometer under both steady and dynamic shear. The ER activity of the composite material suspensions showed higher ER effects for the product with the rod-like structures than for the product with the sphere-like structures. The typical ER behaviour showed by the polyaniline-vanadium oxide nanocomposites demonstrated their potential application as an ER smart material.

Goswami, Sumita; Brehm, Tiago; Filonovich, Sergej; Cidade, Maria Teresa

2014-10-01

279

Interaction of silicon-based quantum dots with gibel carp liver: oxidative and structural modifications  

PubMed Central

Quantum dots (QDs) interaction with living organisms is of central interest due to their various biological and medical applications. One of the most important mechanisms proposed for various silicon nanoparticle-mediated toxicity is oxidative stress. We investigated the basic processes of cellular damage by oxidative stress and tissue injury following QD accumulation in the gibel carp liver after intraperitoneal injection of a single dose of 2 mg/kg body weight Si/SiO2 QDs after 1, 3, and 7 days from their administration. QDs gradual accumulation was highlighted by fluorescence microscopy, and subsequent histological changes in the hepatic tissue were noted. After 1 and 3 days, QD-treated fish showed an increased number of macrophage clusters and fibrosis, while hepatocyte basophilia and isolated hepatolytic microlesions were observed only after substantial QDs accumulation in the liver parenchyma, at 7 days after IP injection. Induction of oxidative stress in fish liver was revealed by the formation of malondialdehyde and advanced oxidation protein products, as well as a decrease in protein thiol groups and reduced glutathione levels. The liver enzymatic antioxidant defense was modulated to maintain the redox status in response to the changes initiated by Si/SiO2 QDs. So, catalase and glutathione peroxidase activities were upregulated starting from the first day after injection, while the activity of superoxide dismutase increased only after 7 days. The oxidative damage that still occurred may impair the activity of more sensitive enzymes. A significant inhibition in glucose-6-phosphate dehydrogenase and glutathione-S-transferase activity was noted, while glutathione reductase remained unaltered. Taking into account that the reduced glutathione level had a deep decline and the level of lipid peroxidation products remained highly increased in the time interval we studied, it appears that the liver antioxidant defense of Carassius gibelio does not counteract the oxidative stress induced 7 days after silicon-based QDs exposure in an efficient manner. PMID:23718202

2013-01-01

280

CW bismuth fibre laser  

Microsoft Academic Search

A new fibre laser based on a bismuth-doped aluminosilicate glass fibre is proposed and fabricated. CW lasing is obtained in the spectral region between 1150 and 1300 nm. The fibres are fabricated by the method of modified chemical vapour deposition. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text

Evgenii M. Dianov; V. V. Dvoyrin; V. M. Mashinsky; A. A. Umnikov; M. V. Yashkov; A. N. Gur'yanov

2005-01-01

281

Determining mean thickness of the oxide layer by mapping the surface of a silicon sphere.  

PubMed

To determine Avogadro constant with a relative uncertainty of better than 2 x 10(-8), the mean thickness of the oxide layer grown non-uniformly on the silicon sphere should be determined with about 0.1 nm uncertainty. An effective and flexible mapping strategy is proposed, which is insensitive to the angle resolution of the sphere-rotating mechanism. In this method, a sphere-rotating mechanism is associated with spectroscopic ellipsometer to determine the distribution of the layer, and a weighted mean method based on equal-area projection theory is applied to estimate the mean thickness. The spectroscopic ellipsometer is calibrated by X-ray reflectivity method. Within 12 hours, eight hundred positions on the silicon sphere are measured twice. The mean thickness is determined to be 4.23 nm with an uncertainty of 0.13 nm, which is in the acceptable level for the Avogadro project. PMID:20389754

Zhang, Jitao; Li, Yan; Wu, Xuejian; Luo, Zhiyong; Wei, Haoyun

2010-03-29

282

A 200 V silicon-on-sapphire LDMOS structure with a step oxide extended field plate  

NASA Astrophysics Data System (ADS)

Fabrication of power integrated circuits on silicon-on-sapphire (SOS) substrates has rarely been considered before. Hence, there is a lack of research in lateral power devices integrated on SOS. Self-heating effects in existing silicon-on-insulator (SOI) lateral power devices degrade the device performance and their reliability. Use of SOS substrates could alleviate these problems though they would require a different approach in lateral power device engineering. This paper purposes a new power SOS LDMOS structure with reduced transient self-heating effects and enhanced current capability compared to the conventional SOI counterpart. The proposed lateral power structure integrated on SOS substrates is analyzed by electro-thermal simulations. The field plate is enlarged (extended field plate (EFP)) along the drift region, reaching the drain region. The EFP includes an oxide step which improves the "on-state resistance-breakdown voltage" trade-off ( RONxS- Vbr).

Roig, J.; Flores, D.; Rebollo, J.; Hidalgo, S.; Millan, J.

2004-02-01

283

Band offsets of a ruthenium gate on ultrathin high-{kappa} oxide films on silicon  

SciTech Connect

Valence-band and conduction-band edges of ultrathin oxides (SiO{sub 2}, HfO{sub 2}, Hf{sub 0.7}Si{sub 0.3}O{sub 2}, and Al{sub 2}O{sub 3} grown on silicon) and their shifts upon sequential metallization with ruthenium have been measured using synchrotron-radiation-excited x-ray, ultraviolet, and inverse photoemissions. From these techniques, the offsets between the valence-band and conduction-band edges of the oxides, and the ruthenium metal gate Fermi edge have been directly measured. In addition the core levels of the oxides and the ruthenium have been characterized. Upon deposition, Ru remains metallic and no chemical alteration of the underlying oxide gates, or interfacial SiO{sub 2} in the case of the high-{kappa} thin films, can be detected. However a clear shift of the band edges is measured for all samples due to the creation of an interface dipole at the ruthenium-oxide interface. Using the energy gap, the electron affinity of the oxides, and the ruthenium work function that have been directly measured on these samples, the experimental band offsets are compared to those predicted by the induced gap states model.

Rangan, Sylvie; Bersch, Eric; Bartynski, Robert Allen; Garfunkel, Eric; Vescovo, Elio [Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854 (United States); Department of Chemistry and Chemical Biology and Laboratory for Surface Modification, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854 (United States); National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2009-02-15

284

Composition, process, and apparatus, for removal of water and silicon mu-oxides from chlorosilanes  

DOEpatents

A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising: (a) a support; and (b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula: R.sub.a-x MCl.sub.x wherein: M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum; R is alkyl; a is a number equal to the valency of metal M; and x is a number having a value from 0 to a, inclusive; and wherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of: (i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula: SiH.sub.4"y Cl.sub.y, wherein y is a number having a value of from 1 to 3, inclusive; and (ii) reaction of such compound(s) with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y wherein y is a number having a value of 1 to 3, inclusive. A corresponding method of making the scavenger composition, and of purifying a chlorosilane which contains oxygen and silicon mu-oxide impurities, likewise are disclosed, together with a purifier apparatus, in which a bed of the scavenger composition is disposed. The composition, purification process, and purifier apparatus of the invention have utility in purifying gaseous chlorosilanes which are employed in the semiconductor industry as silicon source reagents for forming epitaxial silicon layers.

Tom, Glenn M. (New Milford, CT); McManus, James V. (Danbury, CT)

1991-10-15

285

Process for removal of water and silicon mu-oxides from chlorosilanes  

DOEpatents

A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising: (a) a support; and (b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula: R.sub.a-x MCl.sub.x wherein: M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum; R is alkyl; a is a number equal to the valency of metal M; and x is a number having a value of from 0 to a, inclusive; and wherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of: (i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y, wherein y is a number having a value of from 1 to 3, inclusive; and (ii) reaction of such compound(s) with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y wherein y is a number having a value of 1 to 3, inclusive. A corresponding method of making the scavenger composition, and of purifying a chlorosilane which contains oxygen and silicon mu-oxide impurities, likewise are disclosed, together with a purifier apparatus, in which a bed of the scavenger composition is disposed. The composition, purification process, and purifier apparatus of the invention have utility in purifying gaseous chlorosilanes which are employed in the semiconductor industry as silicon source reagents for forming epitaxial silicon layers.

Tom, Glenn M. (New Milford, CT); McManus, James V. (Danbury, CT)

1992-03-10

286

Performance analysis of silicon nanowire transistors considering effective oxide thickness of high-k gate dielectric  

NASA Astrophysics Data System (ADS)

We have analyzed the effective oxide thickness (EOT) of the dielectric material for which we have optimum performance and the output characteristics of the silicon nanowire transistors by replacing the traditional SiO2 gate insulator with a material that has a much higher dielectric constant (high-k) gate, materials like Si3N4, Al2O3, Y2O3 and HfO2. We have also analyzed the channel conductance, the effect of a change in thickness, the average velocity of the charge carrier and the conductance efficiency in order to study the performance of silicon nanowire transistors in the nanometer region. The analysis was performed using the Fettoy, a numerical simulator for ballistic nanowire transistors using a simple top of the barrier (Natori) approach, which is composed of several matlab scripts. Our results show that hafnium oxide (HfO2) gate insulator material provides good thermal stability, a high recrystallization temperature and better interface qualities when compared with other gate insulator materials; also the effective oxide thickness of HfO2 is found to be 0.4 nm.

Chandra, S. Theodore; Balamurugan, N. B.

2014-04-01

287

Relationship Between Plasma Emission Intensity and Film Properties for ECR Silicon Oxide Deposition  

NASA Astrophysics Data System (ADS)

A 2.45 GHz electron cyclotron resonance (ECR) reactor, using both silane + O2 and tetraethoxysilane (TEOS) + O_2, was employed to deposit silicon oxide films, which were characterized using IR absorption, multicolor ellipsometry, and ESCA. Optical emission spectrometer was used to monitor Si, O, H, OH, and SiH in SiH4 plasma and Si, O, H, C, CO, CH, C_2, OH, and H2 in TEOS plasma. In SiH4 based deposition the silicon oxide film quality approaches that of thermal oxide for films deposited using O_2/SiH4 ratios higher than 1.0 at 500 W and 5.0 mTorr. Under these conditions no OH emission was detected for O_2/SiH4 ratios lower than 1.0, while no SiH emission was observed for ratios higher than 1.0. In TEOS based deposition the carbon content in the film is less than 1.0 atomic Strong O emission intensity correlated with high film quality for both chemistries. This work was supported by the National Science Foundation under Grant No. EEC-8721545.

Chew, Kok Heng; Augustyniak, Edward; Woods, R. Claude; Shohet, J. Leon

1996-10-01

288

In-Situ Transmission Electron Microscopy Probing of Native Oxide and Artificial Layers on Silicon Nanoparticles for Lithium Ion Batteries  

SciTech Connect

Surface modification of silicon nanoparticle via molecular layer deposition (MLD) has been recently proved to be an effective way for dramatically enhancing the cyclic performance in lithium ion batteries. However, the fundamental mechanism as how this thin layer of coating function is not known, which is even complicated by the inevitable presence of native oxide of several nanometers on the silicon nanoparticle. Using in-situ TEM, we probed in detail the structural and chemical evolution of both uncoated and coated silicon particles upon cyclic lithiation/delithation. We discovered that upon initial lithiation, the native oxide layer converts to crystalline Li2O islands, which essentially increases the impedance on the particle, resulting in ineffective lithiation/delithiation, and therefore low coulombic efficiency. In contrast, the alucone MLD coated particles show extremely fast, thorough and highly reversible lithiation behaviors, which are clarified to be associated with the mechanical flexibility and fast Li+/e- conductivity of the alucone coating. Surprisingly, the alucone MLD coating process chemically changes the silicon surface, essentially removing the native oxide layer and therefore mitigates side reaction and detrimental effects of the native oxide. This study provides a vivid picture of how the MLD coating works to enhance the coulombic efficiency and preserve capacity and clarifies the role of the native oxide on silicon nanoparticles during cyclic lithiation and delithiation. More broadly, this work also demonstrated that the effect of the subtle chemical modification of the surface during the coating process may be of equal importance as the coating layer itself.

He, Yang; Piper, Daniela M.; Gu, Meng; Travis, Jonathan J.; George, Steven M.; Lee, Se-Hee; Genc, Arda; Pullan, Lee; Liu, Jun; Mao, Scott X.; Zhang, Jiguang; Ban, Chunmei; Wang, Chong M.

2014-10-27

289

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared...

2014-04-01

290

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared...

2012-04-01

291

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Bismuth citrate. 73.2110 Section 73.2110...CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. (a) Identity. The color additive bismuth citrate is the synthetically prepared...

2013-04-01

292

High Mobility and Stability of Thin-Film Transistors Using Silicon-Doped Amorphous Indium Tin Oxide Semiconductors  

NASA Astrophysics Data System (ADS)

We report the fabrication of high-performance thin-film transistors (TFTs) with an amorphous silicon indium tin oxide ( a-SITO) channel, which was deposited by cosputtering a silicon dioxide and an indium tin oxide target. The effect of the silicon doping on the device performance and stability of the a-SITO TFTs was investigated. The field-effect mobility and stability under positive bias stress of the a-SITO TFTs with optimized Si content (0.22 at.% Si) dramatically improved to 28.7 cm2/Vs and 1.5 V shift of threshold voltage, respectively, compared with the values (0.72 cm2/Vs and 8.9 V shift) for a-SITO TFTs with 4.22 at.% Si. The role of silicon in a-SITO TFTs is discussed based on various physical and chemical analyses, including x-ray absorption spectroscopy, x-ray photoelectron spectroscopy, and spectroscopic ellipsometry measurements.

Seo, T. W.; Kim, Hyun-Suk; Lee, Kwang-Ho; Chung, Kwun-Bum; Park, Jin-Seong

2014-09-01

293

Oxidation behavior in reaction-bonded aluminum-silicon alloy/alumina powder compacts  

SciTech Connect

Goal of this research is to determine the feasibility of producing low-shrinkage mullite/alumina composites by applying the reaction-bonded alumina (RBAO) process to an aluminum-silicon alloy/alumina system. Mirostructural and compositional changes during heat treatment were studied by removing samples from the furnace at different steps in the heating schedule and then using optical and scanning electron microscopy, EDS and XRD to characterize the powder compacts. Results suggest that the oxidation behavior of the alloy compact is different from the model proposed for the pure Al/alumina system.

Yokota, S.H.

1992-12-01

294

Epitaxial ferromagnetic oxide thin films on silicon with atomically sharp interfaces  

NASA Astrophysics Data System (ADS)

A bottleneck in the integration of functional oxides with silicon, either directly grown or using a buffer, is the usual formation of an amorphous interfacial layer. Here, we demonstrate that ferromagnetic CoFe2O4 films can be grown epitaxially on Si(111) using a Y2O3 buffer layer, and remarkably the Y2O3/Si(111) interface is stable and remains atomically sharp. CoFe2O4 films present high crystal quality and high saturation magnetization.

de Coux, P.; Bachelet, R.; Warot-Fonrose, B.; Skumryev, V.; Lupina, L.; Niu, G.; Schroeder, T.; Fontcuberta, J.; Sánchez, F.

2014-07-01

295

Epitaxial ferromagnetic oxide thin films on silicon with atomically sharp interfaces  

SciTech Connect

A bottleneck in the integration of functional oxides with silicon, either directly grown or using a buffer, is the usual formation of an amorphous interfacial layer. Here, we demonstrate that ferromagnetic CoFe{sub 2}O{sub 4} films can be grown epitaxially on Si(111) using a Y{sub 2}O{sub 3} buffer layer, and remarkably the Y{sub 2}O{sub 3}/Si(111) interface is stable and remains atomically sharp. CoFe{sub 2}O{sub 4} films present high crystal quality and high saturation magnetization.

Coux, P. de [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona (Spain); CEMES-CNRS, 29 rue Jeanne Marvig, BP 94347, Toulouse Cedex 4 (France); Bachelet, R.; Fontcuberta, J.; Sánchez, F., E-mail: fsanchez@icmab.es [Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus de la UAB, 08193 Bellaterra, Barcelona (Spain); Warot-Fonrose, B. [CEMES-CNRS, 29 rue Jeanne Marvig, BP 94347, Toulouse Cedex 4 (France); Skumryev, V. [Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain and Dep. de Física, Univ. Autònoma de Barcelona, 08193 Bellaterra (Spain); Lupina, L.; Niu, G.; Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany)

2014-07-07

296

Ultrasensitive food toxin biosensor using frequency based signals of silicon oxide nanoporous structure  

NASA Astrophysics Data System (ADS)

We report an electrochemically fabricated silicon oxide nanoporous structure for ultrasensitive detection of AfB1 in food by shift in peak frequency corresponding to maximum sensitivity. It has been observed that the impedance sensitivity changes from 19% to 40% (which is only twice) where as the peak frequency shifts from 500 Hz to 50 kHz, for a change in concentration from 1 fg/ml to 1 pg/ml. This has been attributed to the combined effect of the significant pore narrowing with increasing AfB1 concentration and the opposing nature of impedance change within the nanopores and the conducting substrate immediately below the nanoporous layer.

Ghosh, H.; RoyChaudhuri, C.

2013-06-01

297

Chemical Etching of Zinc Oxide for Thin-Film Silicon Solar Cells  

PubMed Central

Abstract Chemical etching is widely applied to texture the surface of sputter-deposited zinc oxide for light scattering in thin-film silicon solar cells. Based on experimental findings from the literature and our own results we propose a model that explains the etching behavior of ZnO depending on the structural material properties and etching agent. All grain boundaries are prone to be etched to a certain threshold, that is defined by the deposition conditions and etching solution. Additionally, several approaches to modify the etching behavior through special preparation and etching steps are provided. PMID:22162035

Hüpkes, Jürgen; Owen, Jorj I; Pust, Sascha E; Bunte, Eerke

2012-01-01

298

A silicon-on-insulator complementary-metal-oxide-semiconductor compatible flexible electronics technology  

NASA Astrophysics Data System (ADS)

This paper reports a simple flexible electronics technology that is compatible with silicon-on-insulator (SOI) complementary-metal-oxide-semiconductor (CMOS) processes. Compared with existing technologies such as direct fabrication on flexible substrates and transfer printing, the main advantage of this technology is its post-SOI-CMOS compatibility. Consequently, high-performance and high-density CMOS circuits can be first fabricated on SOI wafers using commercial foundry and then be integrated into flexible substrates. The yield is also improved by eliminating the transfer printing step. Furthermore, this technology allows the integration of various sensors and microfluidic devices. To prove the concept of this technology, flexible MOSFETs have been demonstrated.

Tu, Hongen; Xu, Yong

2012-07-01

299

Evaluation of silicon oxide cleaning using F2/Ar remote plasma processing  

NASA Astrophysics Data System (ADS)

In this study, chamber cleaning experiments using a F2/Ar remote plasma generated from a toroidal-type remote plasma source were carried out in a plasma enhanced chemical vapor deposition (PECVD) system. The cleaning processes for the various silicon oxide layers, including PE-oxide (deposited by PECVD using SiH4 and N2O), O3-TEOS oxide (deposited by thermal CVD using ozone and TEOS precursor), and BPSG (borophosphosilicate glass), were investigated by varying the various process parameters, such as the F2 gas flow rate, the F2/(F2+Ar) flow ratio, and the cleaning temperature. The species emitted during cleaning were monitored by Fourier transformed infrared spectroscopy and residual gas analysis. Under the current experimental conditions, the cleaning rate of the BPSG was 4.1-5.0 and 3.9-7.3 times higher than that those of the PE-oxide and O3-TEOS oxide layers, respectively, at room temperature and an F2/(F2+Ar) flow ratio of 28.5%-83%. As the cleaning temperature increased from 100 to 350 °C, the cleaning rates of the PE-oxide, O3-TEOS oxide, and BPSG layers were increased by factors of 2.0-3.0, 1.5-2.2, and 3.0-3.4, respectively, at an F2/(F2+Ar) flow ratio of 28%-68%. The F2/(F2+Ar) flow ratio and cleaning temperature were found to be the most critical parameters involved in determining the cleaning rate of the various oxide layers.

Kang, S. C.; Hwang, J. Y.; Lee, N.-E.; Joo, K. S.; Bae, G. H.

2005-07-01

300

Improved fill factors in amorphous silicon solar cells on zinc oxide by insertion of a germanium layer to block impurity incorporation  

E-print Network

Improved fill factors in amorphous silicon solar cells on zinc oxide by insertion of a germanium 80401 (Received 22 September 2003; accepted 25 May 2004) Amorphous silicon based solar cells deposited Institute of Physics. [DOI: 10.1063/1.1773372] The performance of hydrogenated amorphous silicon a

301

Development of silicon electrode enhanced by carbon nanotube and gold nanoparticle composites on silicon neural probe fabricated with complementary metal-oxide-semiconductor process  

NASA Astrophysics Data System (ADS)

We present the fabrication of highly P-doped single crystal silicon electrodes on a silicon probe through complementary metal-oxide-semiconductor (CMOS)-compatible processes. The electrode with diameter of 50 ?m and a separation of 200 ?m is designed for recording/stimulating purposes. Electrochemical impedance spectroscopy indicates that the interfacial impedance of silicon electrodes at 1 KHz is 2.5 ± 0.4 M?, which is equivalent to the result reported from the gold (Au) electrode. To further enhance the charge storage capacity, composites of multi-wall carbon nanotubes (MWCNTs) and Au nanoparticles are electroplated onto the highly P-doped silicon electrode after surface roughness treatments. With optimized electroplating processes, MWCNTs and Au nanoparticles are selectively coated onto the electrode site with only a minimum enlargement in physical diameter of electrode (<10%). However, the typical impedance is reduced to 21 ± 3 k?. Such improvement can be explained by a boost in double-layer capacitance (Cdl) and the reduction in faradic resistances. The measurement of cyclic voltammetry (CV) shows that the cathodal charge storage capacity is up to 35 mC cm-2, which proves the superior performance of composite coatings on silicon electrodes and validates the functionality of reported CMOS-compatible silicon probe.

Zhang, Songsong; Tsang, Wei Mong; Srinivas, Merugu; Sun, Tao; Singh, Navab; Kwong, Dim-Lee; Lee, Chengkuo

2014-05-01

302

Tribology study of reduced graphene oxide sheets on silicon substrate synthesized via covalent assembly.  

PubMed

Reduced graphene oxide (RGO) sheets were covalently assembled onto silicon wafers via a multistep route based on the chemical adsorption and thermal reduction of graphene oxide (GO). The formation and microstructure of RGO were analyzed by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, and water contact angle (WCA) measurements. Characterization by atomic force microscopy (AFM) was performed to evaluate the morphology and microtribological behaviors of the samples. Macrotribological performance was tested on a ball-on-plate tribometer. Results show that the assembled RGO possesses good friction reduction and antiwear ability, properties ascribed to its intrinsic structure, that is, the covalent bonding to the substrate and self-lubricating property of RGO. PMID:20873824

Ou, Junfei; Wang, Jinqing; Liu, Sheng; Mu, Bo; Ren, Junfang; Wang, Honggang; Yang, Shengrong

2010-10-19

303

Gadolinium oxide coated fully depleted silicon-on-insulator transistors for thermal neutron dosimetry  

NASA Astrophysics Data System (ADS)

Fully depleted silicon-on-insulator transistors coated with gadolinium oxide are shown to be effective thermal neutron dosimeters. The theoretical neutron detection efficiency is calculated to be higher for Gd2O3 than for other practical converter materials. Proof-of-concept dosimeter devices were fabricated and tested during thermal neutron irradiation. The transistor current changes linearly with neutron dose, consistent with increasing positive charge in the SOI buried oxide layer generated by ionization from high energy 157Gd(n,?)158Gd conversion electrons. The measured neutron sensitivity is approximately 1/6 the maximum theoretical value, possibly due to electron-hole recombination or conversion electron loss in interconnect wiring above the transistors.

Vitale, Steven A.; Gouker, Pascale M.

2013-09-01

304

Encapsulation of Au Nanoparticles on a Silicon Wafer During Thermal Oxidation  

PubMed Central

We report the behavior of Au nanoparticles anchored onto a Si(111) substrate and the evolution of the combined structure with annealing and oxidation. Au nanoparticles, formed by annealing a Au film, appear to “float” upon a growing layer of SiO2 during oxidation at high temperature, yet they also tend to become partially encapsulated by the growing silica layers. It is proposed that this occurs largely because of the differential growth rates of the silica layer on the silicon substrate between the particles and below the particles due to limited access of oxygen to the latter. This in turn is due to a combination of blockage of oxygen adsorption by the Au and limited oxygen diffusion under the gold. We think that such behavior is likely to be seen for other metal–semiconductor systems. PMID:24163715

2013-01-01

305

Low temperature growth of crystalline magnesium oxide on hexagonal silicon carbide (0001) by molecular beam epitaxy  

SciTech Connect

Magnesium oxide (111) was grown epitaxially on hexagonal silicon carbide (6H-SiC) (0001) substrates at low temperatures by molecular beam epitaxy and a remote oxygen plasma source. The films were characterized by reflection high-energy electron diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. Crystal structure, morphology, and growth rate of the magnesium oxide (MgO) films were found to be dependent on the magnesium flux, indicating a magnesium adsorption controlled growth mechanism. The single crystalline MgO thin films had an epitaxial relationship where MgO (111) parallel 6H-SiC (0001) and were stable in both air and 10{sup -9} Torr up to 1023 K.

Goodrich, T. L.; Parisi, J.; Cai, Z.; Ziemer, K. S. [Department of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115 (United States)

2007-01-22

306

Low temperature growth of crystalline magnesium oxide on hexagonal silicon carbide (0001) by molecular beam epitaxy  

NASA Astrophysics Data System (ADS)

Magnesium oxide (111) was grown epitaxially on hexagonal silicon carbide (6H-SiC) (0001) substrates at low temperatures by molecular beam epitaxy and a remote oxygen plasma source. The films were characterized by reflection high-energy electron diffraction, Auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscopy. Crystal structure, morphology, and growth rate of the magnesium oxide (MgO) films were found to be dependent on the magnesium flux, indicating a magnesium adsorption controlled growth mechanism. The single crystalline MgO thin films had an epitaxial relationship where MgO (111)?6H-SiC (0001) and were stable in both air and 10-9Torr up to 1023K.

Goodrich, T. L.; Parisi, J.; Cai, Z.; Ziemer, K. S.

2007-01-01

307

Self-assisted GaAs nanowires with selectable number density on Silicon without oxide layer  

NASA Astrophysics Data System (ADS)

We present the growth of self-assisted GaAs nanowires (NWs) with selectable number density on bare Si(1?1?1), not covered by the silicon oxide. We determine the number density of the NWs by initially self-assembling GaAs islands on whose top a single NW is nucleated. The number density of the initial GaAs base islands can be tuned by droplet epitaxy and the same degree of control is then transferred to the NWs. This procedure is completely performed during a single growth in an ultra-high vacuum environment and requires neither an oxide layer covering the substrate, nor any pre-patterning technique.

Bietti, S.; Somaschini, C.; Frigeri, C.; Fedorov, A.; Esposito, L.; Geelhaar, L.; Sanguinetti, S.

2014-10-01

308

Reactive atomization of silicon to form in situ oxide sintering aids  

NASA Astrophysics Data System (ADS)

The present investigation demonstrated the feasibility of using reactive atomization to produce Si powder with in situ oxide sintering aids. With further process optimization, this powder may be an alternative starting material to the conventional, mechanically blended, Si-plus-oxide powder used to produce commercial sintered reaction bonded silicon nitride (SRBSN). In the reactive atomization approach, yttrium and aluminum additives were introduced into silicon metal during induction melting. Reactive atomization was accomplished using a N2-5 pct O2 mixture as the atomization gas. During atomization, oxygen in the atomization gas reacted with Y and Al in the Si melt to produce Y2O3 and Al2O3, which act as in situ sintering aids. The reactive atomized powder demonstrated a Gaussian distribution with a mean diameter of 36 ?m. The powder fines (<38 ?m) were used to produce cold isostatically pressed compacts that were subsequently reaction bonded and sintered. The results demonstrate that ?-Si3N4 formed during reaction bonding and sintering. The density of the SRBSN was 77 pct of theoretical. Transmission electron microscopy (TEM) studies indicated the presence of a glassy phase on the grain boundaries, which is typical in SRBSN and indicative of the presence of the in situ sintering aids. A kinetic model was used to study the influence of processing parameters, such as droplet temperature and oxygen partial pressure, on the kinetics of oxide formation during reactive atomization. The results suggest that the volume fraction of oxides increases with increasing droplet temperature and oxygen partial pressure in the atomization gas mixture.

Wu, Y.; Zeng, X.; Lavernia, E. J.; Schoenung, J. M.

1996-08-01

309

Ultrasmooth reaction-sintered silicon carbide surface resulting from combination of thermal oxidation and ceria slurry polishing.  

PubMed

An ultrasmooth reaction-sintered silicon carbide surface with an rms roughness of 0.424 nm is obtained after thermal oxidation for 30 min followed by ceria slurry polishing for 30 min. By SEM-EDX analysis, we investigated the thermal oxidation behavior of RS-SiC, in which the main components are Si and SiC. As the oxidation rate is higher in the area with defects, there are no scratches or cracks on the surface after oxidation. However, a bumpy structure is formed after oxidation because the oxidation rates of Si and SiC differ. Through a theoretical analysis of thermal oxidation using the Deal-Grove model and the removal of the oxide layer by ceria slurry polishing in accordance with the Preston equation, a model for obtaining an ultrasmooth surface is proposed and the optimal processing conditions are presented. PMID:23787665

Shen, Xinmin; Dai, Yifan; Deng, Hui; Guan, Chaoliang; Yamamura, Kazuya

2013-06-17

310

Infrared Characterization of Biotinylated Silicon Oxide Surfaces, Surface Stability and Specific Attachment of Streptavidin  

PubMed Central

Biotinylation of silicon oxide surfaces, surface stability and evolution of these functionalized surfaces under bio-specific attachment of streptavidin were studied using Fourier Transform Infrared Spectroscopy. Adsorption and stability of species or changes in the resulting surfaces were monitored after each step of the attachment processes. The silicon oxide surface was initially derivatized by 3-aminopropyltriethoxysilane (APTES) and the quality of the 3-aminopropylsiloxane (APS) surface was monitored using the Si-O-Si and Si-O-C region of its vibrational spectrum. A strong correlation between surface quality and pre-silanization atmospheric moisture content was established. The vibrational fingerprint of biotinylation was determined, both for physisorption and chemisorption to the surface. A new band (i.e. not previous associated with biotin) at ~1250 cm?1 was identified as a vibrational mode of the biotin ureido group, making it possible to track changes in the biotinylated surface in the presence of streptavidin. Some of the biotin ureido at the surface was found to be affected by the protein adsorption and rinse steps while remaining chemisorbed to the surface. The stability of the APS was found to impact the behavior of the biotinylated surface (measured using the Si-O-Si/Si-O-C and ~1250 cm?1 absorption bands respectively). PMID:19489542

Lapin, Norman A.; Chabal, Yves J.

2009-01-01

311

Oxidized Porous Silicon Particles Covalently Grafted with Daunorubicin as a Sustained Intraocular Drug Delivery System  

PubMed Central

Purpose. To test the feasibility of covalent loading of daunorubicin into oxidized porous silicon (OPS) and to evaluate the ocular properties of sustained delivery of daunorubicin in this system. Methods. Porous silicon was heat oxidized and chemically functionalized so that the functional linker on the surface was covalently bonded with daunorubicin. The drug loading rate was determined by thermogravimetric analysis. Release of daunorubicin was confirmed in PBS and excised rabbit vitreous by mass spectrometry. Daunorubicin-loaded OPS particles (3 mg) were intravitreally injected into six rabbits, and ocular properties were evaluated through ophthalmic examinations and histology during a 3-month study. The same OPS was loaded with daunorubicin using physical adsorption and was evaluated similarly as a control for the covalent loading. Results. In the case of covalent loading, 67 ± 10 ?g daunorubicin was loaded into each milligram of the particles while 27 ± 10 ?g/mg particles were loaded by physical adsorption. Rapid release of daunorubicin was observed in both PBS and excised vitreous (?75% and ?18%) from the physical adsorption loading, while less than 1% was released from the covalently loaded particles. Following intravitreal injection, the covalently loaded particles demonstrated a sustained degradation of OPS with drug release for 3 months without evidence of toxicity; physical adsorption loading revealed a complete release within 2 weeks and localized retinal toxicity due to high daunorubicin concentration. Conclusions. OPS with covalently loaded daunorubicin demonstrated sustained intravitreal drug release without ocular toxicity, which may be useful to inhibit unwanted intraocular proliferation. PMID:23322571

Chhablani, Jay; Nieto, Alejandra; Hou, Huiyuan; Wu, Elizabeth C.; Freeman, William R.; Sailor, Michael J.; Cheng, Lingyun

2013-01-01

312

986 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 17, NO. 5, MAY 2005 Wavelength-Switchable La-Codoped Bismuth-Based  

E-print Network

-Codoped Bismuth-Based Erbium-Doped Fiber Ring Laser H. L. Liu, H. Y. Tam, Senior Member, IEEE, W. H. Chung, P. K. A. Wai, Senior Member, IEEE, and N. Sugimoto Abstract--A wavelength-switchable La-codoped bismuth polarization controller, and a 0.85-m-long La-codoped bis- muth-based Bi-EDF. La-codoped bismuth oxide glass

Wai, Ping-kong Alexander

313

Optical and structural characterization of thermal oxidation effects of erbium thin films deposited by electron beam on silicon  

SciTech Connect

Thermal oxidation effects on the structural, compositional, and optical properties of erbium films deposited on silicon via electron beam evaporation were analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and spectroscopic ellipsometry. A gradual rise in oxidation temperature from 700 to 900 deg. C resulted in a transition from ErO- to Er{sub 2}O{sub 3}-rich phase. Additional increase in oxidation temperature above 1000 deg. C led to the formation of erbium silicate due to further oxygen incorporation, as well as silicon out-diffusion from the substrate. A silicon oxide interfacial layer was also detected, with its thickness increasing with higher oxidation temperature. Additionally, film refractive index decreased, while its Tauc bandgap value increased from {approx}5.2 eV to {approx}6.4 eV, as the oxidation temperature was raised from 700 deg. C to above 900 deg. C. These transformations were accompanied by the appearance of an intense and broad absorption band below the optical gap. Thermal oxidation effects are discussed in the context of film structural characteristics and defect states.

Kamineni, Himani S.; Kamineni, Vimal K.; Moore, Richard L.; Gallis, Spyros; Diebold, Alain C.; Huang Mengbing; Kaloyeros, Alain E. [College of Nanoscale Science and Engineering, University at Albany, 255 Fuller Road, Albany, New York, 12203 (United States)

2012-01-01

314

Adsorption of Silica on Synthetic Iron Oxides Fractionates Stable Silicon Isotopes  

NASA Astrophysics Data System (ADS)

Recent advances show that the quantification of silicon isotopic fractionation by biotic and abiotic processes readily contributes to the understanding of the continental cycle of silicon, involving a.o. Si transfers between aqueous solutions, living organisms and soil minerals. Si uptake by biota, silicate weathering and clay formation all fractionate Si isotopes. Yet, silica may also be quantitatively retrieved from aqueous solutions through specific adsorption of uncharged monosilicic acid (H4SiO4) on oxide surfaces. Iron oxides are ubiquitous in sediments, weathered rocks and soils, where they appear as crystalline and/or short-range ordered (sro) minerals. Here, we report on silicon mass fractionation by H4SiO4 adsorption on two iron oxides: goethite and ferrihydrite. The respective crystalline and sro oxides were synthesized silicon-free and characterized through elementary analysis, selective dissolution, X-ray diffraction and Transmission Electronic Microscopy (TEM). The surface area, as determined by ethylene glycol monoethyl ether (EGME), is 147 m2.g-1 for goethite and 338 m2.g-1 for ferrihydrite. The adsorption of H4SiO4 was measured in batch experiment series designed as function of time (0-504 h) and initial Si concentration in solution (0.2-1.8 mM), at 20°C, constant pH (5.5) and ionic force. The solid:solution ratio was 5g:1000ml. After equilibration, isotopic compositions of 20 selected solution samples were measured on a Nu Plasma Multicollector Mass Spectrometer (MC-ICP-MS) operating in dry plasma mode with external Mg doping. The results were expressed as ?^{29}Si relatively to the NBS28- standard, with an average precision of ± 0.08‰ (± 2?M). With respect to oxide mass but not to EGME-surface area, ferrihydrite (74%) adsorbed more Si than goethite (46%) relatively to initial Si input (at 1.1 mM Si initial concentration after 504 h of contact). Measured against its initial composition (0.00 ± 0.09‰), the equilibrium solution was systematically enriched in the heavy isotope, reaching a maximum ?^{29}Si-value of +0.50 ± 0.08‰ and +0.70 ± 0.07‰ for goethite and ferrihydrite, respectively (both at the 1.1 mM Si initial concentration after 504 h of contact). For all the experimental series, the progressive ?^{29}Si enrichment of the equilibrium solution fitted to a Rayleigh distillation path. The fractionation factors ranged between 0.78 ± 0.22‰ and 0.54 ± 0.06‰. The Si-isotopic signatures imprinted by H4SiO4 adsorption on goethite and ferrihydrite did not differ neither between goethite and ferrihydrite, nor between series having different initial Si-concentrations in solution. Our results show that Si-isotopic fractionation induced by H4SiO4 adsorption onto iron oxides is similar to the one generated by biological processes such as plant uptake and biomineralization by diatoms. They may have major implications on the Si-isotopic signature of natural waters in various ecosystems.

Delstanche, S.; Opfergelt, S.; Cardinal, D.; André, L.; Delvaux, B.

2006-12-01

315

High quality of ultra-thin silicon oxynitride films formed by low-energy nitrogen implantation into silicon with additional plasma or thermal oxidation  

Microsoft Academic Search

Silicon oxynitride (SiOxNy) insulators have been obtained by low-energy molecular nitrogen ion (N2+) implantation in Si substrates prior to thermal or high density O2 ECR (electron cyclotron resonance) or N2O RP (remote plasma) plasma oxidation at temperatures of 20°C and 350°C, respectively. Characterization by Fourier transform infrared (FTIR) analyses reveals the high structural quality and very low Si–N bond concentration

J. A. Diniz; A. P. Sotero; G. S. Lujan; P. J. Tatsch; J. W. Swart

2000-01-01

316

Numerically controlled atmospheric-pressure plasma sacrificial oxidation using electrode arrays for improving silicon-on-insulator layer uniformity  

NASA Astrophysics Data System (ADS)

Silicon-on-insulator (SOI) wafers are important semiconductor substrates in high-performance devices. In accordance with device miniaturization requirements, ultrathin and highly uniform top silicon layers (SOI layers) are required. A novel method involving numerically controlled (NC) atmospheric-pressure plasma sacrificial oxidation using an electrode array system was developed for the effective fabrication of an ultrathin SOI layer with extremely high uniformity. Spatial resolution and oxidation properties are the key factors controlling ultraprecision machining. The controllability of plasma oxidation and the oxidation properties of the resulting experimental electrode array system were examined. The results demonstrated that the method improved the thickness uniformity of the SOI layer over one-sixth of the area of an 8-in. wafer area.

Takei, Hiroyasu; Yoshinaga, Keinosuke; Matsuyama, Satoshi; Yamauchi, Kazuto; Sano, Yasuhisa

2015-01-01

317

High performance of graphene oxide-doped silicon oxide-based resistance random access memory  

PubMed Central

In this letter, a double active layer (Zr:SiO x /C:SiO x ) resistive switching memory device with outstanding performance is presented. Through current fitting, hopping conduction mechanism is found in both high-resistance state (HRS) and low-resistance state (LRS) of double active layer RRAM devices. By analyzing Raman and FTIR spectra, we observed that graphene oxide exists in C:SiO x layer. Compared with single Zr:SiO x layer structure, Zr:SiO x /C:SiO x structure has superior performance, including low operating current, improved uniformity in both set and reset processes, and satisfactory endurance characteristics, all of which are attributed to the double-layer structure and the existence of graphene oxide flakes formed by the sputter process. PMID:24261454

2013-01-01

318

Silicon nanowire oxidation: the influence of sidewall structure and gold distribution.  

PubMed

The oxidation behavior of Si nanowires (SiNWs) grown by the gold (Au) catalyzed vapor-liquid-solid (VLS) growth process in an electron beam evaporation (EBE) reactor is studied. The VLS SiNWs exhibit hexagonal shape with essentially {112} facets where each facet shows a saw-tooth faceting itself, consisting of alternating {111} and {113} facets. Depending on growth temperatures (450-750 degrees C) and evaporation currents (40-80 mA) that determine the silicon vapor supply, this facet formation is more or less pronounced. The diffusion of Au atoms on the faceted SiNW surfaces and the formation of Au nanoparticles on the SiNW facets during growth and during ex situ annealing are studied. Upon diffusion, the Au atoms agglomerate and form Au nanoparticles that preferably arrange themselves on {113} facets. Upon annealing in air at temperatures between 800 and 950 degrees C the gold nanoparticles agglomerate further and form bigger particles of a few tens of nm in diameter that reside at the interface between the growing silica (SiO(2)) layer and the SiNW itself, which in turn shrinks during SiNW oxidation. The oxide layer thickness and the oxide appearance depend on the annealing conditions (time and temperature) and systematically varied oxidation processing is described in this paper as investigated by cross-sectional transmission electron microscopy (TEM) including high resolution studies as well as scanning electron microscopy (SEM) studies. Our results strongly suggest that the SiNWs can be fully oxidized, thus forming silica NWs that can either keep their initial shape or, under certain annealing conditions, do not keep their initial wire shape but assume a bamboo-like shape that forms most likely as a result of locally high stresses that are related to nanocrack formation. The nanocracks form in the growing oxide layer mediated by the presence of Au nanoparticles that yield gold-enhanced SiNW oxidation and thus a faster oxidation rate. PMID:19738306

Sivakov, V A; Scholz, R; Syrowatka, F; Falk, F; Gösele, U; Christiansen, S H

2009-10-01

319

Surface contamination and damage from CF4 and SF6 reactive ion etching of silicon oxide on gallium arsenide  

Microsoft Academic Search

Two reactive ion etchants, CF4 and SF6, have been compared in terms of plasma characteristics, silicon oxide etch characteristics, extent of RIE damage, and formation of barrier layers on a GaAs surface after oxide etch. It was found that higher etch rates with lower plasma-induced dc bias can be achieved with SF6 plasma relative to CF4 plasma and that this

K. L. Seaward; N. J. Moll; W. F. Stickle

1990-01-01

320

Surface contamination and damage from CF 4 and SF 6 reactive ion etching of silicon oxide on gallium arsenide  

Microsoft Academic Search

Two reactive ion etchants, CF4 and SF6, have been compared in terms of plasma characteristics, silicon oxide etch characteristics, extent of RIE damage, and formation\\u000a of barrier layers on a GaAs surface after oxide etch. It was found that higher etch rates with lower plasma-induced dc bias\\u000a can be achieved with SF6 plasma relative to CF4 plasma and that this

K. L. Seaward; N. J. Moll; W. F. Stickle

1990-01-01

321

Hydrogen incorporation and radiation induced dynamics in metal-oxide-silicon structures: A study using nuclear reaction analysis  

Microsoft Academic Search

Resonant Nuclear Reaction Analysis (NRA), using the H-1\\/N-15, alpha gamma\\/c-12 reaction at 6.4 MeV, is successfully applied to the investigation of hydrogen incorporation and radiation induced migration in metal oxide silicon structures. The influence of processing parameters on the H content of thermal oxides, with and without gate material present, is studied. Hydrogen accumulation at the Si-SiO2 interface is reproducibly

M. A. Briere

1993-01-01

322

Compatibility of cobalt and chromium depletion gates with RPECVD upper gate oxide for silicon-based nanostructures  

Microsoft Academic Search

Three-dimensional confinement of electrons in silicon-based nanodevices may be achieved using a dual gate structure to confine carriers laterally in a 2D MOSFET inversion layer. We have investigated the temperature stability of cobalt and chromium for thin depletion gates, using remote plasma enhanced chemical vapour deposited (RPECVD) 0268-1242\\/13\\/8A\\/022\\/img9 for the deposited dielectric. The thermal stability of the oxide\\/metal\\/oxide structure for

M. J. Rack; A. D. Gunther; M. Khoury; D. Vasileska; D. K. Ferry; M. Sidorov

1998-01-01

323

Void and Nanostructure Formations during Thermal Decomposition of 20-nm-Thick Silicon Oxide Layer on Si(100)  

NASA Astrophysics Data System (ADS)

We investigate the thermal decomposition of 20-nm-thick silicon oxide layers on Si(100) at a temperature of 1050 °C in vacuum by X-ray photoelectron spectroscopy, scanning Auger electron microscopy, and atomic force microscopy. Time evolutions of chemical-shift components in Si 2p core-level spectra are analyzed with the SiO2-decomposition model based on void formation. The experimental data can be reproduced well if the void area is proportional to the square of the annealing time, being consistent with the model in which the reaction at the void periphery is the rate-limiting step for void growth. Microscopic images show that the void periphery is square with rounded corners, and many silicon nanostructures are formed inside the void. These observations reflect reaction processes of the thermal decomposition of the silicon oxide layer.

Enta, Yoshiharu; Ogawa, Kano; Nagai, Takayuki

2013-03-01

324

ATOMIC-LAYER-DEPOSITED ALUMINUM OXIDE FOR THE SURFACE PASSIVATION OF HIGH-EFFICIENCY SILICON SOLAR CELLS  

E-print Network

ATOMIC-LAYER-DEPOSITED ALUMINUM OXIDE FOR THE SURFACE PASSIVATION OF HIGH-EFFICIENCY SILICON SOLAR to those measured on reference cells passivated by an aluminum-annealed thermal SiO2, while those of the Al of aluminum ox- ide (Al2O3) grown by atomic layer deposition (ALD) pro- vide an excellent level of sur

325

Preparation of magnetic and bioactive calcium zinc iron silicon oxide composite for hyperthermia treatment of bone cancer  

E-print Network

Preparation of magnetic and bioactive calcium zinc iron silicon oxide composite for hyperthermia]. Therefore hyperthermia at between 43 and 45°C is expected to be one of the most useful treatments of bone, the hyperthermia treatment can be classified as microwave thermotherapy, RF thermotherapy, ultrasonic thermotherapy

Qin, Qinghua

326

hal-00087421,version2-21Dec2006 The interface between a polar perovskite oxide and silicon from  

E-print Network

hal-00087421,version2-21Dec2006 The interface between a polar perovskite oxide and silicon from). Many of them belong to the class of perovskites (cubic crystals whose chemical formula is ABO3) which structure. In the search of the best candidate, the LaAlO3 crystal raised out of the perovskite family

Paris-Sud XI, Université de

327

Hot-pressed silicon nitride with various lanthanide oxides as sintering additives  

NASA Technical Reports Server (NTRS)

The effects of addition of various lanthanide oxides and their mixture with Y2O3 on the sintering of Si3N4 were investigated. The addition of simple and mixed lanthanide oxides promoted the densification of Si3N4 in hot-pressing at 1800 C under 300-400kg/ centimeters squared for 60 min. The crystallization of yttrium and lanthanide-silicon oxynitrides which was observed inn the sintered body containing yttrium-lanthanide mixed oxides as additives led to the formation of a highly refractory Si3N4 ceramic having a bending strength of 82 and 84 kg/millimeters squared at room temperature and 1300 C respectively. In a Y2O3+La2O3 system, a higher molar ratio of La2O3 to Y2O3 gave a higher hardness and strength at high temperatures. It was found that 90 min was an optimum sintering time for the highest strength.

Ueno, K.; Toibana, Y.

1984-01-01

328

Bismuth ochers from San Diego Co., California  

USGS Publications Warehouse

The chief points brought out in this paper may be briefly summarized as follows: (1) The existence of natural Bi2O3 has not been established. (2) Natural bismite or bismuth ocher, when pure, is more probably a bismuth hydroxide. (3) The bismuth ochers from San Diego County, California, are either a bismuth hydroxide or bismuth vanadate, pucherite, or mixtures of these two. (4) Pucherite has been found noncrystallin and determined for the first time in the United States.

Schaller, W.T.

1911-01-01

329

Functionalization of oxidized silicon surfaces with methyl groups and their characterization  

NASA Astrophysics Data System (ADS)

Oxidized silicon surfaces were functionalized with chemically bonded methyl end groups and characterized by means of Fourier transform infrared (FTIR) spectroscopy with the attenuated total reflection (ATR) method, contact angle measurements, scanning force microscopy (SFM), and thermal desorption spectroscopy (TDS). Detailed results are presented for trimethylsilyl (TMS) and pentamethyldisilyl (PMDS) terminated surfaces, which were prepared by silanization with suitable chloro compounds. The IR spectra of the TMS-terminated surface exhibit two CH stretching peaks at 2904 and 2963 cm -1. In the thermal desorption experiments desorption of trimethylsilanol and methane was observed at 550 ?C. The IR spectra of the PMDS-terminated surface show two CH stretching peaks at 2898 and 2955 cm -1. The thermal desorption spectra indicate cleavage of Si-Si bonds and desorption of trimethylsilane at 530 ?C. The wetting behavior, adhesion, and mechanical properties were studied by contact angle measurements and SFM. The results are compared with the well-defined Si(111)-(1×1):H surface and a self-assembled monolayer (SAM) on a silicon surface with long hydrocarbon chains, prepared with octadecyltrichlorosilane (OTS, H 3C(CH 2) 17SiCl 3). The water contact angle was 82 ? for TMS and 85 ? for PMDS end groups. The friction forces measured for the TMS- and PMDS-terminated surfaces were comparable and about 3 times higher than that of the H-terminated silicon and the OTS-SAM surface. The corresponding friction coefficients were 0.17, 0.18, 0.34, and 0.45 for Si(111)-(1×1):H, OTS SAM, TMS, and PMDS surfaces, respectively.

Schmohl, A.; Khan, A.; Hess, P.

2004-07-01

330

Demonstration of nitric oxide on asbestos and silicon carbide fibers with a new ultraviolet spectrophotometric assay.  

PubMed

Nitric oxide (NO) has a number of important functions in biological systems and may play a role in the toxicity of mineral fibers. We investigated whether NO might be present on the surface of mineral fibers and if crocidolite could adsorb NO from NO gas or cigarette smoke. NO was determined with a new gas chromatography-ultraviolet spectrophotometric technique after thermal desorption from the fiber surface and injection in a gas flow cell. NO was found in different amounts on chrysotile B, crocidolite, amosite, and silicon carbide whiskers. There was a strong correlation between the amount of NO and the specific surface area of these fibers (r = 0.98). NO could not be demonstrated on rockwool fibers [man-made vitreous fiber(s) (MMVF)21 and MMVF22] or silicon nitride whiskers. NO on crocidolite, amosite, and silicon carbide whiskers was readily desorbed from the fibers at increased temperature, while NO on chrysotile B seemed to be more firmly adsorbed to the fiber and required a longer period of time to be desorbed. The amount of NO bound to crocidolite increased from 34 micrograms/g fiber to 85 and 474 micrograms/g after exposing the fibers to cigarette smoke and NO gas, respectively. These findings indicate that a) NO adsorbs to fiber surfaces, b) some fibers adsorb more NO than others, c) some fibers adsorb NO more strongly than others, and d) the amounts of NO on fibers may be increased after exposure of the fiber to cigarette smoke or other sources of NO. The biological significance of NO on mineral fibers remains to be investigated. PMID:9400696

Leanderson, P; Lagesson, V; Tagesson, C

1997-09-01

331

Field emission from zinc oxide nanorod bundles grown on silicon nanoporous pillar array  

NASA Astrophysics Data System (ADS)

A large-area zinc oxide (ZnO) nanorod bundle array was grown on a silicon nanoporous pillar array (Si-NPA) substrate by a chemical vapor deposition method, and its field-emission properties was studied. The structural characterization disclosed that the bundles were composed of hexagonal ZnO nanorods growing along c-axis and taking roots into the silicon pillars of Si-NPA. The average diameter and length of the ZnO nanorods were ?145 nm and ?10 ?m, respectively. The field-emission measurements showed that the turn-on field of ZnO/Si-NPA was 4.6 V/?m with an emission current density (ECD) of 1 ?A/cm2, and an ECD of 420 ?A/cm2 was achieved at an applied field of 8.89 V/?m. The field enhancement factor was calculated to be ?1700 based on the Fowler-Nordheim theory. According to the obtained charge coupled device (CCD) image, the density and brightness of the emission dots increased with the applied field, and the high emission dot density was attributed to the formation of a large number of ZnO nanorod emitting tips. Our results indicated that ZnO/Si-NPA might be a promising electron emission source.

Wang, Ling Li; Gong, Shang Dong; Wu, Li Hong; Li, Xin Jian

2013-04-01

332

Combined dislocation and process modeling for local oxidation of silicon structure  

NASA Astrophysics Data System (ADS)

Recent work on modeling dislocation behavior in small semiconductor structures is extended to the level of complexity appropriate to actual manufacturing situations. The dislocation-dynamics code PARANOID is generalized to handle arbitrary geometries and unstructured stress tables, and combined with commercial process-modeling software to study the dislocation configurations which arise during the growth of the well-known local oxidation of silicon "bird's beak" structure. Experimentally observed dislocation patterns are reproduced with considerable fidelity. The observed Hu loop configuration is matched to 90% accuracy, provided that the long-range thermal mismatch stresses arising from cooldown are included. It is concluded that the main remaining obstacle to predicting dislocation behavior during device manufacture lies in the difficulty of utilizing current three-dimensional process-modeling codes to obtain reliable stress fields.

Chidambarrao, D.; Liu, X. H.; Schwarz, K. W.

2002-11-01

333

Highly transparent nonvolatile resistive memory devices from silicon oxide and graphene.  

PubMed

Transparent electronic memory would be useful in integrated transparent electronics. However, achieving such transparency produces limits in material composition, and hence, hinders processing and device performance. Here we present a route to fabricate highly transparent memory using SiO(x) as the active material and indium tin oxide or graphene as the electrodes. The two-terminal, nonvolatile resistive memory can also be configured in crossbar arrays on glass or flexible transparent platforms. The filamentary conduction in silicon channels generated in situ in the SiO(x) maintains the current level as the device size decreases, underscoring their potential for high-density memory applications, and as they are two-terminal based, transitions to three-dimensional memory packages are conceivable. As glass is becoming one of the mainstays of building construction materials, and conductive displays are essential in modern handheld devices, to have increased functionality in form-fitting packages is advantageous. PMID:23033077

Yao, Jun; Lin, Jian; Dai, Yanhua; Ruan, Gedeng; Yan, Zheng; Li, Lei; Zhong, Lin; Natelson, Douglas; Tour, James M

2012-01-01

334

Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst  

PubMed Central

Integrating a silicon solar cell with a recently developed cobalt-based water-splitting catalyst (Co-Pi) yields a robust, monolithic, photo-assisted anode for the solar fuels process of water splitting to O2 at neutral pH. Deposition of the Co-Pi catalyst on the Indium Tin Oxide (ITO)-passivated p-side of a np-Si junction enables the majority of the voltage generated by the solar cell to be utilized for driving the water-splitting reaction. Operation under neutral pH conditions fosters enhanced stability of the anode as compared to operation under alkaline conditions (pH 14) for which long-term stability is much more problematic. This demonstration of a simple, robust construct for photo-assisted water splitting is an important step towards the development of inexpensive direct solar-to-fuel energy conversion technologies. PMID:21646536

Pijpers, Joep J. H.; Winkler, Mark T.; Surendranath, Yogesh; Buonassisi, Tonio; Nocera, Daniel G.

2011-01-01

335

Paralinear Oxidation of Silicon Nitride in a Water Vapor/Oxygen Environment  

NASA Technical Reports Server (NTRS)

Three silicon nitride materials were exposed to dry oxygen flowing at 0.44 cm/s at temperatures between 1200 and 1400 C. Reaction kinetics were measured with a continuously recording microbalance. Parabolic kinetics were observed. When the same materials were exposed to a 50% H2O - 50% O2 gas mixture flowing at 4.4 cm/s, all three types exhibited paralinear kinetics. The material is oxidized by water vapor to form solid silica. The protective silica is in turn volatilized by water vapor to form primarily gaseous Si(OH)4. Nonlinear least squares analysis and a paralinear kinetic model were used to determine both parabolic and linear rate constants from the kinetic data. Volatilization of the protective silica scale can result in accelerated consumption of Si3N4. Recession rates under conditions more representative of actual combustors are compared to the furnace data.

Fox, Dennis S.; Opila, Elizabeth J.; Nguyen, QuynhGiao; Humphrey, Donald L.; Lewton, Susan M.; Gray, Hugh R. (Technical Monitor)

2002-01-01

336

Effects of inductively coupled plasma oxidation on the properties of polycrystalline silicon films and thin film transistors  

NASA Astrophysics Data System (ADS)

We investigated the effects of inductively coupled plasma (ICP) oxidation on the properties of polycrystalline silicon (poly-Si) films and thin film transistors (TFTs). The ICP oxidation in oxygen plasma passivated the dangling bonds in the poly-Si films, not by oxygen incorporation but by hydrogen incorporation; but the incorporated hydrogen diffused out during the TFT fabrication, so that the effect of the dangling bond passivation was not obtained in the TFT. The ICP oxidation did not remove the intragranular defects such as microtwins and stacking faults, but it reduced the interface trap density and also improved the performance of the poly-Si TFT. The field effect mobility of TFT with an ICP oxide and low-pressure chemical vapor deposited (LPCVD) oxide double layer was 30.6 cm2/V s, while that of TFT with only a LPCVD oxide was 17.2 cm2/V s.

Choi, Yong Woo; Park, Sang Won; Ahn, Byung Tae

1999-05-01

337

The n-silicon/thallium(III) oxide heterojunction photoelectrochemical solar cell  

SciTech Connect

Thallium(III) oxide is a degenerate n-type semiconductor which can be electrochemically or photoelectrochemically deposited on conducting or semiconducting substrates. The material is highly conductive, transparent, and electrocatalytic. A photoelectrochemical cell consisting of the n-silicon/thallium(III) oxide photoanode and a platinum cathode in an alkaline solution of the ferrocyanide/ferricyanide redox couple produced a 0.512V open-circuit photovoltage, 33.5 mA/cm/sup 2/ short-circuit photocurrent density, 0.643 fill factor, and 13.8, photovoltaic efficiency with 80 mW/cm/sup 2/ iR-filtered xenon light. The efficiency was 11.0% with 75.3 mW/cm/sup 2/ natural sunlight, and 22.3% with 800 nm monochromatic light. The short-circuit quantum efficiency at 800 nm was 97%. A xenon photovoltaic efficiency of 10.2% was observed with cast multicrystalline n-silicon. Photocurrent-voltage curves were computer simulated using values of the barrier height (0.96V), diode quality factor (1.2), and series resistance (200..cap omega..) that were measured from dark current voltage and capacitance-voltage curves. A solid-state photovoltaic cell was fabricated by making a low-pressure point contact to the front surface of a dry photoanode. The photovoltaic characteristics of the solid-state cell were nearly identical with those of the photoelectrochemical cell. These results suggest that the photoelectrochemical cell functions like a Schottky-barrier or SIS solid-state photovoltaic cell in series with a highly reversible electrochemical cell.

Switzer, J.A.

1986-04-01

338

High performance multilayered nano-crystalline silicon/silicon-oxide light-emitting diodes on glass substrates.  

PubMed

A low-temperature hydrogenation-assisted sequential deposition and crystallization technique is reported for the preparation of nano-scale silicon quantum dots suitable for light-emitting applications. Radio-frequency plasma-enhanced deposition was used to realize multiple layers of nano-crystalline silicon while reactive ion etching was employed to create nano-scale features. The physical characteristics of the films prepared using different plasma conditions were investigated using scanning electron microscopy, transmission electron microscopy, room temperature photoluminescence and infrared spectroscopy. The formation of multilayered structures improved the photon-emission properties as observed by photoluminescence and a thin layer of silicon oxy-nitride was then used for electrical isolation between adjacent silicon layers. The preparation of light-emitting diodes directly on glass substrates has been demonstrated and the electroluminescence spectrum has been measured. PMID:21860083

Darbari, S; Shahmohammadi, M; Mortazavi, M; Mohajerzadeh, S; Abdi, Y; Robertson, M; Morrison, T

2011-09-16

339

Direct bonding of Cu to oxidized silicon nitride by wetting of molten Cu and Cu(O)  

Microsoft Academic Search

When pressureless sintered silicon nitride with the main additives Y2O3 and Al2O3, having a thermal conductivity K = 20 W\\/m K, was oxidized at 1240–1360 °C in still air, the resulting surface oxide layer easily bonded to a copper plate\\u000a in the temperature region between 1065 and 1083 °C, and in the oxygen concentration range of 0.008–0.39 wt%, as shown in a\\u000a Cu–O phase diagram. The oxide

Shun-Ichiro Tanaka

2010-01-01

340

Oxidative Removal of Boron from Molten Silicon by CaO-based Flux Treatment with Oxygen Gas Injection  

NASA Astrophysics Data System (ADS)

Oxidative removal of boron from molten silicon has been investigated at 1773 K (1500 °C) by CaO-based flux treatment with oxygen gas injection. Since oxygen gas is injected into the silicon melt after adding CaO- or CaCO3-CaF2 flux onto the melt, high oxygen partial pressure is maintained at the flux-O2-Si interface and the removal of boron proceeds under nonequilibrium conditions. The experimental results clarified that the behavior of boron removal from molten silicon depends on the competition between the oxidation reactions of boron and silicon. On the basis of the results obtained, optimum operating conditions for boron removal by the flux treatment were examined from the viewpoints of initial flux composition, reaction time, oxygen gas flow rate, and orifice size of gas injection nozzle. By repeating the batch operation for 120 seconds three times under the optimum conditions determined in the present study, boron concentration in metallurgical-grade silicon could be reduced from 14 to 7.6 mass ppm efficiently.

Tanahashi, Mitsuru; Fujisawa, Toshiharu; Yamauchi, Chikabumi

2014-04-01

341

p-type microcrystalline silicon oxide emitter for silicon heterojunction solar cells allowing current densities above 40 mA/cm2  

NASA Astrophysics Data System (ADS)

We have developed a microcrystalline silicon oxide (?c-SiOx:H) p-type emitter layer that significantly improves the light incoupling at the front side of silicon heterojunction solar cells by minimizing reflection losses. The ?c-SiOx:H p-layer with a refractive index of 2.87 at 632 nm wavelength and the transparent conducting oxide form a stack with refractive indexes which consecutively decrease from silicon to the ambient air and thus significantly reduce the reflection. Optical simulations performed for flat wafers reveal that the antireflective effect of the emitter overcompensates the parasitic absorption and suggest an ideal thickness of about 40 nm. On textured wafers, the increase in current density is still more than 1 mA/cm2 for a typical emitter thickness of 10 nm. Thus, we are able to fabricate heterojunction solar cells with current densities significantly over 40 mA/cm2 and power conversion efficiency above 20%, which is yet mainly limited by the cell's fill factor.

Mazzarella, L.; Kirner, S.; Stannowski, B.; Korte, L.; Rech, B.; Schlatmann, R.

2015-01-01

342

Influence of various rare-earth oxide additives on microstructure and mechanical properties of silicon nitride based nanocomposites  

Microsoft Academic Search

Influence of rare-earth oxide additives (La2O3, Nd2O3, Y2O3, Yb2O3 and Lu2O3) on the microstructure and mechanical properties of hot-pressed silicon nitride\\/silicon carbide micro\\/nanocomposites has been investigated. The results were consequently compared to those obtained on the reference monolithic Si3N4 sintered with the same additives. The composites exhibited finer microstructure compared to monolithic materials and the aspect ratio of ?-Si3N4 grains

Peter Tatarko; Štefánia Lojanová; Ján Dusza; Pavol Šajgalík

2010-01-01

343

Sintered-reaction Bonded Silicon Nitride Densified by a Gas Pressure Sintering Process Effects of Rare Earth Oxide Sintering Additives  

Microsoft Academic Search

Reaction-bonded silicon nitrides containing rare-earth oxide sintering additives were densified by gas pressure sintering. The sintering behavior, microstructure and mechanical properties of the resultant specimens were analyzed. For that purpose, Lu2O3-SiO2 (US), La2O3-MgO (AM) and Y2O3-Al2O3 (YA) additive systems were selected. Among the tested compositions, densification of silicon nitride occurred at the lowest temperature when using the La2O3-MgO system. Since

S. H. Lee; J. W. Ko; Y. J. Park; H. D. Kim; Hua-Tay Lin; Paul F Becher

2012-01-01

344

Silicon carbide MIS and MOS development using alternative nitride and oxide dielectrics  

NASA Astrophysics Data System (ADS)

Magnesium oxide and magnesium calcium oxide, MgO and MgxCa 1-xO, were grown as gate dielectrics on 6H-SiC (0001) by molecular beam epitaxy for the first time. MOS diodes of MgO/SiC and Mg.75Ca .25O/SiC showed electrical breakdown fields, Ebb reaching 3.1 and 3.7 MV/cm2, respectively. An optimal Ebd of 3.7 MV/cm2 was achieved by a combination of a substrate chemical mechanical polish (CMP) treatment in acid solution, ultraviolet ozone (UV/O3) oxidation, and growth of an epitaxial Mg.75Ca .25O dielectric on SiC. The lowest density of interface states, Dit = 1 x 10-11 eV-1cm -2, was achieved for a film prepared in the same manner, without UV/O 3 exposure. The interface states were attributed to a predominant oxide of the Si-O bond type, determined by XPS to have a binding energy of 102 eV (for Si 2p) and 532.5 eV (for O 1s). In general, the UV/O3 treated diodes showed negative flat-band voltage shifts, Vfb, and higher densities of interface states. CMP treated samples measured positive Vfb, indicative of remnant interface species from polishing. Growth temperatures above 300°C showed no significant increase in Ebd or reduction in Dit, These oxides are presented as low temperature alternatives to SiO2 dielectric, commonly formed by thermal oxidation. Nanocrystalline AlN gate dielectrics were grown by metal-organic MBE (MOMBE) on SiC as an alternative to epitaxial AlN/SiC. The level of oxygen at the AlN/SiC interface could not be effectively reduced by a combination of in-situ thermal cleaning and chemical scavenging using bromide precursors, SiBr4 and CBr4. However, the ratio of silicon to carbon at the interface was controlled by regulating the flow ratio of precursors. The level of carbon deficient at the surface of SiC was compensated by additional CBr4 flux. The nanocrystalline-AlN film, which is in its preliminary stage of development, measured excellent rms roughness of 0.1 nm. The film and interface were shown to be very stable at 300°C by high temperature x-ray reflectivity (HTXRR) measurement.

Stodilka, Danielle O.

345

Continuous-flow Mass Production of Silicon Nanowires via Substrate-Enhanced Metal-Catalyzed Electroless Etching of Silicon with Dissolved Oxygen as an Oxidant  

NASA Astrophysics Data System (ADS)

Silicon nanowires (SiNWs) are attracting growing interest due to their unique properties and promising applications in photovoltaic devices, thermoelectric devices, lithium-ion batteries, and biotechnology. Low-cost mass production of SiNWs is essential for SiNWs-based nanotechnology commercialization. However, economic, controlled large-scale production of SiNWs remains challenging and rarely attainable. Here, we demonstrate a facile strategy capable of low-cost, continuous-flow mass production of SiNWs on an industrial scale. The strategy relies on substrate-enhanced metal-catalyzed electroless etching (MCEE) of silicon using dissolved oxygen in aqueous hydrofluoric acid (HF) solution as an oxidant. The distinct advantages of this novel MCEE approach, such as simplicity, scalability and flexibility, make it an attractive alternative to conventional MCEE methods.

Hu, Ya; Peng, Kui-Qing; Liu, Lin; Qiao, Zhen; Huang, Xing; Wu, Xiao-Ling; Meng, Xiang-Min; Lee, Shuit-Tong

2014-01-01

346

Nickel Nanocrystals Embedded in Metal--Alumina--Nitride--Oxide--Silicon Type Low-Temperature Polycrystalline-Silicon Thin-Film Transistor for Low-Voltage Nonvolatile Memory Application  

NASA Astrophysics Data System (ADS)

In this work, a nickel nanocrystal (Ni-NC) assisted metal--alumina--nitride--oxide--silicon (MANOS) thin-film transistor (TFT) nonvolatile memory (NVM) was fabricated by a standard low temperature polycrystalline silicon (LTPS) TFT process. The size range and density of Ni-NCs were approximately 5--13 nm and 5 × 1011 cm-2, respectively. The programming/erasing (P/E) voltages are decreased down to -10 and +8 V, respectively, by the Fowler--Nordheim tunneling mechanism from gate injection. In this P/E voltage condition, a large memory window (˜4.2 V) was observed by current--voltage measurement. Then, the speed and voltages of P/E were measured and discussed completely. The data retention of the Ni-NC assisted MANOS-LTPS-TFT-NVM is extracted to be 1.62 V of memory window after 104 s.

Wang, Terry Tai-Jui; Liu, Yu-Cheng; Wu, Chien-Hung; Lu, Tien-Lin; Hsieh, Ing-Jar; Kuo, Cheng-Tzu

2011-06-01

347

Nickel Nanocrystals Embedded in Metal-Alumina-Nitride-Oxide-Silicon Type Low-Temperature Polycrystalline-Silicon Thin-Film Transistor for Low-Voltage Nonvolatile Memory Application  

NASA Astrophysics Data System (ADS)

In this work, a nickel nanocrystal (Ni-NC) assisted metal-alumina-nitride-oxide-silicon (MANOS) thin-film transistor (TFT) nonvolatile memory (NVM) was fabricated by a standard low temperature polycrystalline silicon (LTPS) TFT process. The size range and density of Ni-NCs were approximately 5-13 nm and 5 ×1011 cm-2, respectively. The programming/erasing (P/E) voltages are decreased down to -10 and +8 V, respectively, by the Fowler-Nordheim tunneling mechanism from gate injection. In this P/E voltage condition, a large memory window (˜4.2 V) was observed by current-voltage measurement. Then, the speed and voltages of P/E were measured and discussed completely. The data retention of the Ni-NC assisted MANOS-LTPS-TFT-NVM is extracted to be 1.62 V of memory window after 104 s.

Tai-Jui Wang, Terry; Liu, Yu-Cheng; Wu, Chien-Hung; Lu, Tien-Lin; Hsieh, Ing-Jar; Kuo, Cheng-Tzu

2011-06-01

348

The silicon/zinc oxide interface in amorphous silicon-based thin-film solar cells: Understanding an empirically optimized contact  

NASA Astrophysics Data System (ADS)

The electronic structure of the interface between the boron-doped oxygenated amorphous silicon "window layer" (a-SiOx:H(B)) and aluminum-doped zinc oxide (ZnO:Al) was investigated using hard x-ray photoelectron spectroscopy and compared to that of the boron-doped microcrystalline silicon (?c-Si:H(B))/ZnO:Al interface. The corresponding valence band offsets have been determined to be (-2.87 ± 0.27) eV and (-3.37 ± 0.27) eV, respectively. A lower tunnel junction barrier height at the ?c-Si:H(B)/ZnO:Al interface compared to that at the a-SiOx:H(B)/ZnO:Al interface is found and linked to the higher device performances in cells where a ?c-Si:H(B) buffer between the a-Si:H p-i-n absorber stack and the ZnO:Al contact is employed.

Gerlach, D.; Wilks, R. G.; Wippler, D.; Wimmer, M.; Lozac'h, M.; Félix, R.; Mück, A.; Meier, M.; Ueda, S.; Yoshikawa, H.; Gorgoi, M.; Lips, K.; Rech, B.; Sumiya, M.; Hüpkes, J.; Kobayashi, K.; Bär, M.

2013-07-01

349

Boosting the local anodic oxidation of silicon through carbon nanofiber atomic force microscopy probes  

PubMed Central

Summary Many nanofabrication methods based on scanning probe microscopy have been developed during the last decades. Local anodic oxidation (LAO) is one of such methods: Upon application of an electric field between tip and surface under ambient conditions, oxide patterning with nanometer-scale resolution can be performed with good control of dimensions and placement. LAO through the non-contact mode of atomic force microscopy (AFM) has proven to yield a better resolution and tip preservation than the contact mode and it can be effectively performed in the dynamic mode of AFM. The tip plays a crucial role for the LAO-AFM, because it regulates the minimum feature size and the electric field. For instance, the feasibility of carbon nanotube (CNT)-functionalized tips showed great promise for LAO-AFM, yet, the fabrication of CNT tips presents difficulties. Here, we explore the use of a carbon nanofiber (CNF) as the tip apex of AFM probes for the application of LAO on silicon substrates in the AFM amplitude modulation dynamic mode of operation. We show the good performance of CNF-AFM probes in terms of resolution and reproducibility, as well as demonstration that the CNF apex provides enhanced conditions in terms of field-induced, chemical process efficiency.

Lorenzoni, Matteo; Matsui, Soichiro; Tanemura, Masaki; Perez-Murano, Francesc

2015-01-01

350

Effect of ultraviolet light exposure to boron doped hydrogenated amorphous silicon oxide thin film  

NASA Astrophysics Data System (ADS)

We have investigated the effect of ultraviolet (UV) light exposure to boron doped (p-type) hydrogenated amorphous silicon oxide (p-a-SiO:H) thin semiconductor films by measuring changes in its structural, electrical and optical properties. After a 50 h of UV light soaking (LS) of the films, that have 1.2, 6.9, 15.2, 25.3 at.% oxygen content (C(O)) and optical gap (E04) of 1.897, 2.080, 2.146 and 2.033 eV, show a relative increase in the C(O) by 28.0%, 9.8%, 2.0%, 3.1%, a relative increase in the Urbach energy (Eu) by 42%, 24%, 8%, 0%, decrease in the E04 by 66, 2, 12, 19 meV and the gap state defect density (Nd) show an increase by 6.5%, 3.4%, 0.7%, 0.1%. At higher oxygen content the observed UV light induced degradation (LID) is relatively less than that for films with lower oxygen content, indicating that higher oxides face less changes under the UV light.

Baek, Seungsin; Iftiquar, S. M.; Jang, Juyeon; Lee, Sunhwa; Kim, Minbum; Jung, Junhee; Park, Hyeongsik; Park, Jinjoo; Kim, Youngkuk; Shin, Chonghoon; Lee, Youn-Jung; Yi, Junsin

2012-11-01

351

Microwave spectroscopic measurements of intermediate products in ECR silicon oxide deposition plasmas  

NASA Astrophysics Data System (ADS)

Microwave spectroscopy in the 75-110 GHz range was applied to measure densities of 20 molecules in O_2+TEOS (tetraethoxysilane) and O_2+SiH_4/SiF_4/CF4 silicon oxide deposition plasmas created in a 2.45 GHz electron cyclotron resonance (ECR) reactor. In the O_2+TEOS system, sequential oxidation products of the ethoxy fragments from TEOS were observed: C_2H_5OH, CH_3CHO, CH_2CO, CH_3OH, H_2CO, and HCOOH. In fuorinated silane-based plasmas neutral CH_xF_4-x, OCF_2,FHCO, CF_2, SiH_xF_4-x, and SiF_2, as well as the SiF^+ ion, were monitored. The SiF^+ density increased with plasma power, while concentrations of the neutral molecules decreased with power. It appears that the dissociation of molecular species is very extensive at the higher power used in industrial microelectronics applications. This work was supported by the NSF under Grant No. EEC-8721545.

Woods, R. Claude; Augustyniak, Edward; Chew, Kok Heng; Shohet, J. Leon

1996-10-01

352

Corrosion by liquid lead and lead-bismuth: experimental results review and analysis  

SciTech Connect

Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

Zhang, Jinsuo [Los Alamos National Laboratory

2008-01-01

353

Investigation of the threshold voltage shift effect of lanthanum(III) oxide on tin/hafnium dioxide/lanthanum oxide/silicon dioxide/silicon stacks  

NASA Astrophysics Data System (ADS)

The semiconductor industry continues to scale (shrink) transistor dimensions to both increase the number of transistors per integrated circuit and their speed. One important aspect of scaling is the need to decrease the equivalent oxide thickness of the transistor gate dielectric while minimizing leakage current. Traditional thin layer SiO2 or SiOxNy films have been replaced by higher dielectric constant film stacks Here we study one example, the HfO2/La2O3/SiO 2 stack. This dissertation describes an investigation of the use of La2O3 to reduce the threshold voltage of TiN/HfO 2/SiO2/Si stacks (high-kappa/metal gate stacks). A significant aspect of this study is the determination of band alignment for a series of high-kappa/metal gate stacks that explore the effect of placement and thickness of the Lanthanum oxide layer. In order to achieve this goal, a number of film stack properties were determined including film thicknesses, band gap of the high-kappa oxides, the flat band voltages, Si band bending, and the valence band and conduction band offsets. The first part of this work was measurement of individual layer thickness in the multi-layer film stacks using spectroscopic ellipsometry (SE) and other complementary techniques. In order to more completely understand the SE measurements, complementary techniques were used. These techniques include angle resolved X-ray photoelectron spectroscopy (ARXPS), X-ray reflectivity (XRR), transmission electron microscopy (TEM), and Rutherford backscattering spectroscopy (RBS). In this dissertation, we show that SE can simultaneously measure HfO 2 and SiO2 thicknesses in HfO2/SiO2/Si stacks. We discuss the difficulties in simultaneous measurement of all films in the La oxide Hf oxide film stack. The second part of this dissertation is the measurement of the band gap of high-kappa films. The band gap of a high-kappa film is an important parameter because it affects the conduction band offset (CBO) between high-kappa and Si substrate. The CBO affects the gate leakage current of the transistor. The band gap of high-kappa films was determined from the complex refractive index using several different methods. Comparisons of plots of the extinction coefficient (k), absorption coefficient (alpha), and optical models for imaginary part of the dielectric function (epsilon2) show that each method gives slightly different values for the band gap. The Cody Lorentz model for the dielectric function provides a useful model for the defect induced sub-band gap absorption. We show the impact of the subband gap absorption on band gap extrapolation. Because the existence of sub band gap states is well documented in the literature, we use the Cody Lorentz model to determine the band gap. The next step was to determine band alignment of the valence and conduction bands the layers in the film stack. X-Ray photoelectron spectroscopy (XPS) measurements were used to determine the valence band offset (VBO) and silicon band bending. The conduction band levels were determined from the valence band energy levels and the band gap. The CBO we measured (1.77eV) is well above the specified minimum CBO for Hf oxide (1.0eV). We developed a band alignment model to account for the trends that we observed. Our data is consistent with the presence of a dipole at the high-kappa/SiO2 interface. According to this model, the change in VBO is a direct measure of the change in the interface dipole moment. Because the combination of capacitance -- voltage (C-V) and XPS to measure the flat band voltage and Si band bending, respectively, has rarely been used, relationship between these two quantities has not been discussed in the literature. The agreement between an empirical, theoretical relationship between flat band voltage vs. Si band and our data suggests that XPS can be a useful tool for examining VT shift layers in high-kappa gate stacks. We also investigated the effect of the SiO2 thickness and growth method on the flat band voltage of TiN/HfO2/La2O 3/SiO2/Si stacks. We observed no change in flat band voltage for stacks wit

di, Ming

354

Hexagonal Ag nanoarrays induced enhancement of blue light emission from amorphous oxidized silicon nitride via localized surface plasmon coupling.  

PubMed

A significant enhancement of blue light emission from amorphous oxidized silicon nitride (a-SiNx:O) films is achieved by introduction of ordered and size-controllable arrays of Ag nanoparticles between the silicon substrate and a-SiNx:O films. Using hexagonal arrays of Ag nanoparticles fabricated by nanosphere lithography, the localized surface plasmons (LSPs) resonance can effectively increase the internal quantum efficiency from 3.9% to 13.3%. Theoretical calculation confirms that the electromagnetic field-intensity enhancement is through the dipole surface plasma coupling with the excitons of a-SiNx:O films, which demonstrates a-SiNx:O films with enhanced blue emission are promising for silicon-based light-emitting applications by patterned Ag arrays. PMID:25402058

Ma, Zhongyuan; Ni, Xiaodong; Zhang, Wenping; Jiang, Xiaofan; Yang, Huafeng; Yu, Jie; Wang, Wen; Xu, Ling; Xu, Jun; Chen, Kunji; Feng, Duan

2014-11-17

355

Gold-bismuth clusters.  

PubMed

Metal clusters have interesting characteristics, such as the relationship between properties and size of the cluster. This is not always apparent, so theoretical studies can provide relevant information. In this report, optimized structures and electron donor-acceptor properties of AunBim clusters are reported (n + m = 2-7, 20). Density functional theory calculations were performed to obtain optimized structures. The ground states of gold clusters formed with up to seven atoms are planar. The presence of Bi modifies the structure, and the clusters become 3-D. Several optimized geometries have at least one Bi atom bonded to gold or bismuth atoms and form structures similar to NH3. This fragment is also present in clusters with 20 atoms, where the formation of Au3Bi stabilizes the structures. Bismuth clusters are better electron donors and worse electron acceptors than gold clusters. Mixed clusters fall in between these two extremes. The presence of Bi atoms in gold clusters modifies the electron donor-acceptor properties of the clusters, but there is no correlation between the number of Bi atoms present in the cluster and the capacity for donating electrons. The effect of planarity in Au19Bi clusters is the same as that in Au20 clusters. The properties of pure gold clusters are certainly interesting, but clusters formed by Bi and Au are more important because the introduction of different atoms modifies the geometry, the stability, and consequently the physical and chemical properties. Apparently, the presence of Bi may increase the reactivity of gold clusters, but further studies are necessary to corroborate this hypothesis. PMID:24963953

Martínez, Ana

2014-08-01

356

Transparent conducting oxide contacts and textured metal back reflectors for thin film silicon solar cells  

NASA Astrophysics Data System (ADS)

With the growing population and the increasing environmental problems of the 'common' fossil and nuclear energy production, the need for clean and sustainable energy sources is evident. Solar energy conversion, such as in photovoltaic (PV) systems, can play a major role in the urgently needed energy transition in electricity production. At the present time PV module production is dominated by the crystalline wafer technology. Thin film silicon technology is an alternative solar energy technology that operates at lower efficiencies, however, it has several significant advantages, such as the possibility of deposition on cheap (flexible) substrates and the much smaller silicon material consumption. Because of the small thickness of the solar cells, light trapping schemes are needed in order to obtain enough light absorption and current generation. This thesis describes the research on thin film silicon solar cells with the focus on the optimization of the transparent conducting oxide (TCO) layers and textured metal Ag substrate layers for the use as enhanced light scattering back reflectors in n-i-p type of solar cells. First we analyzed ZnO:Al (TCO) layers deposited in an radio frequent (rf) magnetron deposition system equipped with a 7 inch target. We have focused on the improvement of the electrical properties without sacrificing the optical properties by increasing the mobility and decreasing the grain boundary density. Furthermore, we described some of the effects on light trapping of ZnO:Al enhanced back reflectors. The described effects are able to explain the observed experimental data. Furthermore, we present a relation between the surface morphology of the Ag back contact and the current enhancement in microcrystalline (muc-Si:H) solar cells. We show the importance of the lateral feature sizes of the Ag surface on the light scattering and introduce a method to characterize the quality of the back reflector by combining the vertical and lateral feature sizes at this surface. Additionally, we show that we can control the lateral feature sizes and obtain an optimized roughness for light scattering. With this new knowledge we were able to indicate the influence of the surface plasmon absorption of the textured Ag layers on the current enhancement and recognize this effect as one of the limiting factors to the current increase in thin film solar cells. Finally we present the dark and light current voltage (J-V) parameters of muc-Si:H solar cells as a function of the rms roughness of the substrate. We show that increased roughness can result in an increased defect density of the absorbing silicon layer (i layer), which limits the current collection in the solar cell. The presented research gives better understanding of the effect of TCOs and textured interfaces on light trapping and current enhancement in thin film silicon solar cells. The thesis explains some fundamental insights in light scattering and reveals some material and morphology features that are dominantly limiting the current generation in muc-Si:H solar cells deposited on light scattering back reflectors. Furthermore, it presents a method to obtain optimized back scattering contacts at deposition temperatures below 300 oC, which opens the possibility for the use of heat resistant plastic substrates. We improved the muc-Si:H solar cell efficiency with flat back reflectors from 4.5 % and 14.6 mA/cm2 to 8.5 % and 23.4 mA/cm2 with the use of optimized back reflectors.

Franken, R. H.-J.

2006-09-01

357

Efficient and stable photo-oxidation of water by a bismuth vanadate photoanode coupled with an iron oxyhydroxide oxygen evolution catalyst.  

PubMed

BiVO(4) films were prepared by a simple electrodeposition and annealing procedure and studied as oxygen evolving photoanodes for application in a water splitting photoelectrochemical cell. The resulting BiVO(4) electrodes maintained considerable photocurrent for photo-oxidation of sulfite, but generated significantly reduced photocurrent for photo-oxidation of water to oxygen, also decaying over time, suggesting that the photoelectrochemical performance of BiVO(4) for water oxidation is mainly limited by its poor catalytic ablity to oxidize water. In order to improve the water oxidation kinetics of the BiVO(4) electrode, a layer of FeOOH was placed on the BiVO(4) surface as an oxygen evolution catalyst using a new photodeposition route. The resulting BiVO(4)/FeOOH photoanode exhibitied significantly improved photocurrent and stability for photo-oxidation of water, which is one of the best among all oxide-based phoatoanode systems reported to date. In particular, the BiVO(4)/FeOOH photoanode showed an outstanding performance in the low bias region (i.e., E < 0.8 V vs RHE), which is critical in determining the overall operating current density when assembling a complete p-n photoelectrochemical diode cell. The photocurrent-to-O(2) conversion efficiency of the BiVO(4)/FeOOH photoanode is ca. 96%, confirming that the photogenerated holes in the BiVO(4)/FeOOH photoanode are indeed excusively used for O(2) evolution. PMID:22263661

Seabold, Jason A; Choi, Kyoung-Shin

2012-02-01

358

Microstructure, oxidation behavior and mechanical behavior of lens deposited niobium-titanium-silicon and niobium-titanium-silicon based alloys  

Microsoft Academic Search

With current high temperature structural materials such as nickel based superalloys being pushed to the limits of suitable operating conditions, there comes a need for replacement materials with even higher temperature capabilities. Niobium silicon based systems have been shown to have superior density normalized strength at elevated temperatures when compared to currently used alloys. The drawbacks associated with the niobium

Ryan Richard Dehoff

2008-01-01

359

Role of surface oxides in the formation of solid-electrolyte interphases at silicon electrodes for lithium-ion batteries.  

PubMed

Nonaqueous solvents in modern battery technologies undergo electroreduction at negative electrodes, leading to the formation of a solid-electrolyte interphase (SEI). The mechanisms and reactions leading to a stable SEI on silicon electrodes in lithium-ion batteries are still poorly understood. This lack of understanding inhibits the rational design of electrolyte additives, active material coatings, and the prediction of Li-ion battery life in general. We prepared SEI with a common nonaqueous solvent (LiPF6 in PC and in EC/DEC 1:1 by wt %) on silicon oxide and etched silicon (001) surfaces in various states of lithiation to understand the role of surface chemistry on the SEI formation mechanism and SEI structure. Anhydrous and anoxic techniques were used to prevent air and moisture contamination of prepared SEI films, allowing for more accurate characterization of SEI chemical stratification and composition by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profiling. Additionally, multivariate statistical methods were used to better understand TOF-SIMS depth profiling studies. We conclude that the absence of native-oxide layer on silicon has a significant impact on the formation, composition, structure, and thickness of the SEI. PMID:25402271

Schroder, Kjell W; Dylla, Anthony G; Harris, Stephen J; Webb, Lauren J; Stevenson, Keith J

2014-12-10

360

Homopolyatomic Bismuth Ions, Part 2= Electronic Excitations in Homopolyatomic Bismuth Cations: Spectroscopic  

E-print Network

Homopolyatomic Bismuth Ions, Part 2= Electronic Excitations in Homopolyatomic Bismuth Cations of the low-valence bismuth cluster cations Bi5 3 , Bi8 2 , and Bi9 5 have been studied with experimental and theoretical tech- niques. The UV-visible spectra of the bismuth ions were measured in acidic chloroaluminate

Glaser, Rainer

361

Behaviour of Antimony and Bismuth in Copper Electrorefining Circuits  

SciTech Connect

Antimony- and bismuth-rich copper anodes, anode slimes and decopperized anode slimes from industrial copper electrorefineries were studied mineralogically. Antimony in the anodes occurs mainly as Cu-Pb-As-Sb-Bi oxide inclusions along the copper grain boundaries; bismuth is mainly present as Cu-Pb-As-Sb-Bi oxide, Cu-Bi-As oxide, Cu-Pb-As-Bi oxide and Cu-Bi oxide inclusions. Sb and Bi partly dissolve during electrorefining, but extensively reprecipitate as As-Sb oxide, As-Sb-Bi oxide and SbAsO4. The presence of As results in the precipitation of essentially all the Bi as BiAsO4. The decopperizing process dissolves much of the Sb and Bi, although the majority of the BiAsO4 phase remains unaffected. Subsequently, some of the dissolved Sb and Bi reprecipitates as various oxide, sulphate and arsenate species. X-ray absorption near-edge structure (XANES) analyses suggest about 70% of the antimony in the anode slimes is present in the pentavalent oxidation state. The XANES analyses indicate that most of the Bi in all the slimes samples is present in the trivalent oxidation state.

Beauchemin,S.; Chen, T.; Dutrizac, J.

2008-01-01

362

Electronic devices containing switchably conductive silicon oxides as a switching element and methods for production and use thereof  

DOEpatents

In various embodiments, electronic devices containing switchably conductive silicon oxide as a switching element are described herein. The electronic devices are two-terminal devices containing a first electrical contact and a second electrical contact in which at least one of the first electrical contact or the second electrical contact is deposed on a substrate to define a gap region therebetween. A switching layer containing a switchably conductive silicon oxide resides in the the gap region between the first electical contact and the second electrical contact. The electronic devices exhibit hysteretic current versus voltage properties, enabling their use in switching and memory applications. Methods for configuring, operating and constructing the electronic devices are also presented herein.

Tour, James M; Yao, Jun; Natelson, Douglas; Zhong, Lin; He, Tao

2013-11-26

363

Improving the stability of nanostructured silicon thin film lithium-ion battery anodes through their controlled oxidation.  

PubMed

Silicon and partially oxidized silicon thin films with nanocolumnar morphology were synthesized by evaporative deposition at a glancing angle, and their performance as lithium-ion battery anodes was evaluated. The incorporated oxygen concentration was controlled by varying the partial pressure of water during the deposition and monitored by quartz crystal microbalance, X-ray photoelectron spectroscopy. In addition to bulk oxygen content, surface oxidation and annealing at low temperature affected the cycling stability and lithium-storage capacity of the films. By simultaneously optimizing all three, films of ~2200 mAh/g capacity were synthesized. Coin cells made with the optimized films were reversibly cycled for ~120 cycles with virtually no capacity fade. After 300 cycles, 80% of the initial reversible capacity was retained. PMID:22372404

Abel, Paul R; Lin, Yong-Mao; Celio, Hugo; Heller, Adam; Mullins, C Buddie

2012-03-27

364

Effect of ion-irradiation induced defects on the nanocluster Si/Er{sup 3+} coupling in Er-doped silicon-rich silicon oxide  

SciTech Connect

The effect of ion-irradiation induced defects on the nanocluster Si/Er{sup 3+} coupling in Er-doped silicon-rich silicon oxide (SRSO) thin film is investigated. Er-doped SRSO, which consists of silicon nanoclusters (nc-Si) in a SiO{sub 2} matrix, was fabricated using electron-cyclotron resonance plasma enhanced chemical vapor deposition using SiH{sub 4} and O{sub 2} with concurrent sputtering of Er followed by a high temperature annealing. Defects were introduced into the film via irradiation with 3 MeV Si ions and subsequently removed by high temperature annealings. The authors find that ion irradiation reduces Er{sup 3+} luminescence from SRSO films, even when the excitation cross section and luminescence efficiency of Er{sup 3+} ions are completely restored. On the other hand, ion irradiation increases the intrinsic nc-Si luminescence and has little effect on the Er{sup 3+} luminescence from a similarly prepared, Er-doped SiO{sub 2} film, indicating that the presence of irradiation induced defects in the initial amorphous film can reduce the number of Er{sup 3+} ions available for nc-Si mediated luminescence by as much as a factor of 3.

Seo, Se-Young; Jeong, Hoon; Shin, Jung H.; Choi, Han Woo; Woo, Hyung Joo; Kim, Joon Kon [Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1, Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Ion Beam Application Group, Korean Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of)

2007-07-09

365

High-temperature modeling and characterization of 6H silicon carbide metal-oxide-semiconductor field-effect transistors  

NASA Astrophysics Data System (ADS)

We expand upon previous work [S. K. Powell, N. Goldsman, J. M. McGarrity, J. Bernstein, C. J. Scozzie, and A. Lelis, J. Appl. Phys. 92, 4053 (2002)] by applying the device model to 6H silicon carbide metal-oxide-semiconductor field-effect transistors operating at high temperatures. We compare the model predictions with the device measurements from room temperature to 200 °C and find agreement.

Powell, Stephen K.; Goldsman, Neil; Lelis, Aivars; McGarrity, James M.; McLean, Flynn B.

2005-02-01

366

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2010 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2010-04-01

367

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2011 CFR

...and (b). (2) Color additive mixtures of bismuth oxychloride...restrictions. The color additive bismuth oxychloride...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2011-04-01

368

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2011 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2011-04-01

369

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2010 CFR

...and (b). (2) Color additive mixtures of bismuth oxychloride...restrictions. The color additive bismuth oxychloride...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2010-04-01

370

The optical properties of bismuth nanowires  

E-print Network

The optical absorption of bismuth nanowires in the energy (wavenumber) range of 600 - 4000cm-1 is studied. Optical reflection and transmission spectra reveal that bismuth nanowires have a large and intense absorption peak ...

Black, Marcie R. (Marcie Rochelle)

2003-01-01

371

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2013 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2013-04-01

372

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2014 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2014-04-01

373

21 CFR 73.1162 - Bismuth oxychloride.  

Code of Federal Regulations, 2012 CFR

...Specifications. The color additive bismuth oxychloride...be avoided by good manufacturing practice: Volatile...restrictions. The color additive bismuth oxychloride...consistent with good manufacturing practice. (d) Labeling. The color additive and any mixture...

2012-04-01

374

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2014 CFR

...and (b). (2) Color additive mixtures of bismuth oxychloride...restrictions. The color additive bismuth oxychloride...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2014-04-01

375

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2013 CFR

...and (b). (2) Color additive mixtures of bismuth oxychloride...restrictions. The color additive bismuth oxychloride...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2013-04-01

376

21 CFR 73.2162 - Bismuth oxychloride.  

Code of Federal Regulations, 2012 CFR

...and (b). (2) Color additive mixtures of bismuth oxychloride...restrictions. The color additive bismuth oxychloride...amounts consistent with good manufacturing practice. (c) Labeling. The color additive and any mixture...

2012-04-01

377

Prospect of charge enhancement by increasing top oxide thickness of silicon-on-insulator fin field effect transistors  

NASA Astrophysics Data System (ADS)

The variation of electrostatic and transport characteristics of silicon-on-insulator fin field effect transistors (FinFETs) having sub-10 nm fin dimensions is investigated with the variation of top oxide thickness. Capacitance voltage and ballistic transport characteristics of double gate (DG) and triple gate (TG) FinFETs are obtained by self-consistently solving the coupled Schrödinger's and Poisson's equations. Performance enhancement can be obtained in terms of both on-state current and inversion capacitance by increasing the top oxide thickness of highly scaled FinFETs. The work suggests limiting values of the device parameter to differentiate the DG and TG variants of FinFET.

Zunaid Baten, Md.; Islam, Raisul; Amin, Emran Md.; Khosru, Quazi D. M.

2011-09-01

378

Growth of cubic silicon carbide on oxide using polysilicon as a seed layer for micro-electro-mechanical machine applications  

Microsoft Academic Search

The growth of highly oriented 3C–SiC directly on an oxide release layer, composed of a 20-nm-thick poly-Si seed layer and a 550-nm-thick thermally deposited oxide on a (111)Si substrate, was investigated as an alternative to using silicon-on-insulator (SOI) substrates for freestanding SiC films for MEMS applications. The resulting SiC film was characterized by X-ray diffraction (XRD) with the X-ray rocking

C. L. Frewin; C. Locke; J. Wang; P. Spagnol; S. E. Saddow

2009-01-01

379

Enhanced Light Emission of Light-Emitting Diodes with Silicon Oxide Nanobowls Photonic Crystal without Electrical Performance Damages  

NASA Astrophysics Data System (ADS)

Unencapsulated GaN-based light-emitting diodes (LEDs) with two-dimensional (2D) hexagonal closely-packed silicon oxide nanobowls photonic crystal (PhC) on the indium tin oxide (ITO) transparent conductive layer were fabricated by using polystyrene spheres and sol-gel process. Compared to conventional LEDs with planar ITO layers, the light output power of 600-nm-lattice PhC LEDs was improved by 25.6% at an injection current of 20 mA. Furthermore, electrical performance of the PhC LEDs was damage-free via this chemical technique.

Du, Chengxiao; Geng, Chong; Zheng, Haiyang; Wei, Tongbo; Chen, Yu; Zhang, Yiyun; Wu, Kui; Yan, Qingfeng; Wang, Junxi; Li, Jinmin

2013-04-01

380

Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via poole-frenkel hole emission  

NASA Astrophysics Data System (ADS)

A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2 nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (?Vt) vs. programming voltage is studied with and without the silicon nanoparticles. Applying -1 V for 5 s at the gate of the memory with nanoparticles results in a ?Vt of 3.4 V, and the memory window can be up to 8 V with an excellent retention characteristic (>10 yr). Without nanoparticles, at -1 V programming voltage, the ?Vt is negligible. In order to get ?Vt of 3.4 V without nanoparticles, programming voltage in excess of 10 V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1 V the electric field across the 3.6 nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ?Vt vs. electric field across the tunnel oxide shows square root dependence at low fields (E < 1 MV/cm) and a square dependence at higher fields (E > 2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields.

El-Atab, Nazek; Ozcan, Ayse; Alkis, Sabri; Okyay, Ali K.; Nayfeh, Ammar

2014-01-01

381

Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via poole-frenkel hole emission  

SciTech Connect

A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2?nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (?V{sub t}) vs. programming voltage is studied with and without the silicon nanoparticles. Applying ?1?V for 5?s at the gate of the memory with nanoparticles results in a ?V{sub t} of 3.4?V, and the memory window can be up to 8?V with an excellent retention characteristic (>10 yr). Without nanoparticles, at ?1?V programming voltage, the ?V{sub t} is negligible. In order to get ?V{sub t} of 3.4?V without nanoparticles, programming voltage in excess of 10?V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1?V the electric field across the 3.6?nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ?V{sub t} vs. electric field across the tunnel oxide shows square root dependence at low fields (E??2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields.

El-Atab, Nazek; Nayfeh, Ammar [Department of Electrical Engineering and Computer Science (EECS), Institute Center for Microsystems–iMicro, Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates)] [Department of Electrical Engineering and Computer Science (EECS), Institute Center for Microsystems–iMicro, Masdar Institute of Science and Technology, Abu Dhabi (United Arab Emirates); Ozcan, Ayse; Alkis, Sabri [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey)] [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Okyay, Ali K. [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey) [UNAM-National Nanotechnology Research Center and Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey); Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara (Turkey)

2014-01-06

382

Effect of annealing on silicon heterojunction solar cells with textured ZnO:Al as transparent conductive oxide  

NASA Astrophysics Data System (ADS)

We report on silicon heterojunction solar cells using textured aluminum doped zinc oxide (ZnO:Al) as a transparent conductive oxide (TCO) instead of flat indium tin oxide. Double side silicon heterojunction solar cell were fabricated by radio frequency plasma enhanced chemical vapor deposition on high life time N-type float zone crystalline silicon wafers. On both sides of these cells we have deposited by radio frequency magnetron sputtering ZnO:Al layers of thickness ranging from 800 nm to 1400 nm. These TCO layers were then textured by dipping the samples in a 0.5% hydrochloric acid. External quantum efficiency as well as I-V under 1 sun illumination measurements showed an increase of the current for the cells using textured ZnO:Al. The cells were then annealed at 150 °C, 175 °C and 200 °C during 30 min in ambient atmosphere and characterized at each annealing step. The results show that annealing has no impact on the open circuit voltage of the devices but that up to a 175 °C it enhances their short circuit current, consistent with an overall enhancement of their spectral response. Our results suggest that ZnO:Al is a promising material to increase the short circuit current (Jsc) while avoiding texturing the c-Si substrate.

Salomon, A.; Courtois, G.; Charpentier, C.; Labrune, M.; Prod'Homme, P.; Francke, L.; Cabarrocas, P. Roca i.

2012-07-01

383

Oxidation of nanopores in a silicon membrane: self-limiting formation of sub-10 nm circular openings  

NASA Astrophysics Data System (ADS)

We describe a simple but reliable approach to shrink silicon nanopores with nanometer precision for potential high throughput biomolecular sensing and parallel DNA sequencing. Here, nanopore arrays on silicon membranes were fabricated by a self-limiting shrinkage of inverted pyramidal pores using dry thermal oxidation at 850 °C. The shrinkage rate of the pores with various initial sizes saturated after 4 h of oxidation. In the saturation regime, the shrinkage rate is within ± 2 nm h-1. Oxidized pores with an average diameter of 32 nm were obtained with perfect circular shape. By careful design of the initial pore size, nanopores with diameters as small as 8 nm have been observed. Statistics of the pore width show that the shrinkage process did not broaden the pore size distribution; in most cases the distribution even decreased slightly. The progression of the oxidation and the deformation of the oxide around the pores were characterized by focused ion beam and electron microscopy. Cross-sectional imaging of the pores suggests that the initial inverted pyramidal geometry is most likely the determining factor for the self-limiting shrinkage.

Zhang, Miao; Schmidt, Torsten; Sangghaleh, Fatemeh; Roxhed, Niclas; Sychugov, Ilya; Linnros, Jan

2014-09-01

384

Bismuth Passivation Technique for High-Resolution X-Ray Detectors  

NASA Technical Reports Server (NTRS)

The Athena-plus team requires X-ray sensors with energy resolution of better than one part in 3,000 at 6 keV X-rays. While bismuth is an excellent material for high X-ray stopping power and low heat capacity (for large signal when an X-ray is stopped by the absorber), oxidation of the bismuth surface can lead to electron traps and other effects that degrade the energy resolution. Bismuth oxide reduction and nitride passivation techniques analogous to those used in indium passivation are being applied in a new technique. The technique will enable improved energy resolution and resistance to aging in bismuth-absorber-coupled X-ray sensors. Elemental bismuth is lithographically integrated into X-ray detector circuits. It encounters several steps where the Bi oxidizes. The technology discussed here will remove oxide from the surface of the Bi and replace it with nitridized surface. Removal of the native oxide and passivating to prevent the growth of the oxide will improve detector performance and insulate the detector against future degradation from oxide growth. Placing the Bi coated sensor in a vacuum system, a reduction chemistry in a plasma (nitrogen/hydrogen (N2/H2) + argon) is used to remove the oxide and promote nitridization of the cleaned Bi surface. Once passivated, the Bi will perform as a better X-ray thermalizer since energy will not be trapped in the bismuth oxides on the surface. A simple additional step, which can be added at various stages of the current fabrication process, can then be applied to encapsulate the Bi film. After plasma passivation, the Bi can be capped with a non-diffusive layer of metal or dielectric. A non-superconducting layer is required such as tungsten or tungsten nitride (WNx).

Chervenak, James; Hess, Larry

2013-01-01

385

Mineral resource of the month: bismuth  

USGS Publications Warehouse

Bismuth compounds are most known for their soothing effects on the stomach, wounds and sores. These properties make the compounds an essential part of many medicinal and cosmetic preparations, which until 1930 accounted for about 90 percent of the bismuth used. The subsequent development of low-melting alloys and chemical catalysts containing bismuth, as well as its use as an additive to casting alloys, has resulted in a wider variety of industrial applications for bismuth.

Carlin, James F.

2006-01-01

386

Resonant structures based on amorphous silicon sub-oxide doped with Er3+ with silicon nanoclusters for an efficient emission at 1550 nm  

E-print Network

We present a resonant approach to enhance 1550nm emission efficiency of amorphous silicon sub-oxide doped with Er3+ (a-SiOx) layers with silicon nanoclusters (Si-NC). Two distinct techniques were combined to provide a structure that allowed increasing approximately 12x the 1550nm emission. First, layers of SiO2 were obtained by conventional wet oxidation and a-SiOx matrix was deposited by reactive RF co-sputtering. Secondly, an extra pump channel (4I15/2 to 4I9/2) of Er3+ was created due to Si-NC formation on the same a-SiOx matrix via a hard annealing at 1150 C. The SiO2 and the a-SiOx thicknesses were designed to support resonances near the pumping wavelength (~500nm), near the Si-NC emission (~800nm) and near the a-SiOx emission (~1550nm) enhancing the optical pumping process.

Figueira, D S L; Tessler, L R; Frateschi, N C

2009-01-01

387

Comparison between transient and frequency modulated excitation: application to silicon nitride and aluminum oxide coatings of silicon.  

PubMed

Contactless measurements of the lifetime of charge carriers are presented with varying ways of photo excitation: with and without bias light and pulsed and frequency modulated. These methods are applied to the study of the surface passivation of single crystalline silicon by a-SiN(x):H and Al2O3 coatings. The properties of these coatings are investigated under consideration of the merits of the different methods. PMID:24985850

Klein, D; Ohm, W; Fengler, S; Kunst, M

2014-06-01

388

Permeation mechanisms of pulsed microwave plasma deposited silicon oxide films for food packaging applications  

NASA Astrophysics Data System (ADS)

Silicon oxide barrier layers are deposited on polyethylene terephthalate as permeation barriers for food packaging applications by means of a low pressure microwave plasma. Hexamethyldisiloxane (HMDSO) and oxygen are used as process gases to deposit SiOx coatings via pulsed low pressure plasmas. The layer composition of the coating is investigated by Fourier transform infrared spectroscopy and energy dispersive x-ray spectroscopy to show correlations with barrier properties of the films. The oxygen permeation barrier is determined by the carrier gas method using an electrochemical detector. The transition from low to high barrier films is mapped by the transition from organic SiOxCyHz layers to quartz-like SiO1.7 films containing silanol bound hydrogen. A residual permeation as low as J = 1 ± 0.3 cm3 m-2 day-1 bar-1 is achieved, which is a good value for food packaging applications. Additionally, the activation energy Ep of oxygen permeation is analysed and a strong increase from Ep = 31.5 kJ mol-1 for SiOx CyHz-like coatings to Ep = 53.7 kJ mol-1 for SiO1.7 films is observed by increasing the oxygen dilution of HMDSO:O2 plasma. The reason for the residual permeation of high barrier films is discussed and coating defects are visualized by capacitively coupled atomic oxygen plasma etching of coated substrates. A defect density of 3000 mm-2 is revealed.

Deilmann, Michael; Grabowski, Mirko; Theiß, Sebastian; Bibinov, Nikita; Awakowicz, Peter

2008-07-01

389

Organic-on-silicon complementary metal-oxide-semiconductor colour image sensors  

NASA Astrophysics Data System (ADS)

Complementary metal-oxide-semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor.

Lim, Seon-Jeong; Leem, Dong-Seok; Park, Kyung-Bae; Kim, Kyu-Sik; Sul, Sangchul; Na, Kyoungwon; Lee, Gae Hwang; Heo, Chul-Joon; Lee, Kwang-Hee; Bulliard, Xavier; Satoh, Ryu-Ichi; Yagi, Tadao; Ro, Takkyun; Im, Dongmo; Jung, Jungkyu; Lee, Myungwon; Lee, Tae-Yon; Han, Moon Gyu; Jin, Yong Wan; Lee, Sangyoon

2015-01-01

390

Complementary metal oxide semiconductor-compatible silicon nanowire biofield-effect transistors as affinity biosensors.  

PubMed

Affinity biosensors use biorecognition elements and transducers to convert a biochemical event into a recordable signal. They provides the molecule binding information, which includes the dynamics of biomolecular association and dissociation, and the equilibrium association constant. Complementary metal oxide semiconductor-compatible silicon (Si) nanowires configured as a field-effect transistor (NW FET) have shown significant advantages for real-time, label-free and highly sensitive detection of a wide range of biomolecules. Most research has focused on reducing the detection limit of Si-NW FETs but has provided less information about the real binding parameters of the biomolecular interactions. Recently, Si-NW FETs have been demonstrated as affinity biosensors to quantify biomolecular binding affinities and kinetics. They open new applications for NW FETs in the nanomedicine field and will bring such sensor technology a step closer to commercial point-of-care applications. This article summarizes the recent advances in bioaffinity measurement using Si-NW FETs, with an emphasis on the different approaches used to address the issues of sensor calibration, regeneration, binding kinetic measurements, limit of detection, sensor surface modification, biomolecule charge screening, reference electrode integration and nonspecific molecular binding. PMID:24156488

Duan, Xuexin; Rajan, Nitin K; Izadi, Mohammad Hadi; Reed, Mark A

2013-11-01

391

Seed-layer-free hydrothermal growth of zinc oxide nanorods on porous silicon  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) nanorods were grown on porous silicon (PS) using hydrothermal synthesis without a metal catalyst or a seed layer. Scanning electron microscopy, x-ray diffraction, and temperature-dependent photoluminescence (PL) were carried out to investigate the structural and optical properties of the ZnO-PS sample. Most of the nanorods had an average diameter about of 120 nm and an average length of 5 µm, and were assembled into flower-like clusters where several nanorods were joined at a central point. In some cases, ZnO nanorods were merged in parallel bundles. The ZnO nanorods exhibited an overall compressive residual stress. The Zn-O bond length was 1.953 Å. ZnO-PS exhibited one PL peak in the ultraviolet (UV) range, and two peaks in the visible range. The UV and green emission peak were generated from the ZnO nanorods, while the red emission peak was attributed to the PS. The fitting parameters for Varshni's empirical equation were ? = 8 × 10-4 eV/K, ? = 186 K, and E g (0) = 3.375 eV, and the thermal activation energy was about 32 meV.

Kim, Soaram; Kim, Min Su; Park, Hyunggil; Nam, Giwoong; Yoon, Hyunsik; Leem, Jae-Young

2014-05-01

392

Performance enhancement of ITO/oxide/semiconductor MOS-structure silicon solar cells with voltage biasing  

PubMed Central

In this study, we demonstrate the photovoltaic performance enhancement of a p-n junction silicon solar cell using a transparent-antireflective ITO/oxide film deposited on the spacing of the front-side finger electrodes and with a DC voltage applied on the ITO-electrode. The depletion width of the p-n junction under the ITO-electrode was induced and extended while the absorbed volume and built-in electric field were also increased when the biasing voltage was increased. The photocurrent and conversion efficiency were increased because more photo-carriers are generated in a larger absorbed volume and because the carriers transported and collected more effectively due to higher biasing voltage effects. Compared to a reference solar cell (which was biased at 0 V), a conversion efficiency enhancement of 26.57% (from 12.42% to 15.72%) and short-circuit current density enhancement of 42.43% (from 29.51 to 42.03 mA/cm2) were obtained as the proposed MOS-structure solar cell biased at 2.5 V. In addition, the capacitance-volt (C-V) measurement was also used to examine the mechanism of photovoltaic performance enhancement due to the depletion width being enlarged by applying a DC voltage on an ITO-electrode.

2014-01-01

393

Attachment of 3-(Aminopropyl)triethoxysilane on silicon oxide surfaces: dependence on solution temperature.  

PubMed

Parameters important to the self-assembly of 3-(aminopropyl)triethoxysilane (APTES) on chemically grown silicon oxide (SiO 2) to form an aminopropyl silane (APS) film have been investigated using in situ infrared (IR) absorption spectroscopy. Preannealing to approximately 70 degrees C produces significant improvements in the quality of the film: the APS film is denser, and the Si-O-Si bonds between the molecules and the SiO 2 surface are more structured and ordered with only a limited number of remaining unreacted ethoxy groups. In contrast, post-annealing the functionalized SiO 2 samples after room temperature reaction with APTES (i.e., ex situ annealing) does not lead to any spectral change, suggesting that post-annealing has no strong effect on the horizontal polymerization as suggested earlier. Both IR and ellipsometry data show that the higher the solution temperature, the denser and thinner the APS layer is for a given immersion time. Finally, the APS layer obtained by preannealing the solution at 70 degrees C exhibits a better stability in deionized water than the APS layer prepared at room temperature. PMID:18942864

Pasternack, Robert M; Rivillon Amy, Sandrine; Chabal, Yves J

2008-11-18

394

Organic-on-silicon complementary metal–oxide–semiconductor colour image sensors  

PubMed Central

Complementary metal–oxide–semiconductor (CMOS) colour image sensors are representative examples of light-detection devices. To achieve extremely high resolutions, the pixel sizes of the CMOS image sensors must be reduced to less than a micron, which in turn significantly limits the number of photons that can be captured by each pixel using silicon (Si)-based technology (i.e., this reduction in pixel size results in a loss of sensitivity). Here, we demonstrate a novel and efficient method of increasing the sensitivity and resolution of the CMOS image sensors by superposing an organic photodiode (OPD) onto a CMOS circuit with Si photodiodes, which consequently doubles the light-input surface area of each pixel. To realise this concept, we developed organic semiconductor materials with absorption properties selective to green light and successfully fabricated highly efficient green-light-sensitive OPDs without colour filters. We found that such a top light-receiving OPD, which is selective to specific green wavelengths, demonstrates great potential when combined with a newly designed Si-based CMOS circuit containing only blue and red colour filters. To demonstrate the effectiveness of this state-of-the-art hybrid colour image sensor, we acquired a real full-colour image using a camera that contained the organic-on-Si hybrid CMOS colour image sensor. PMID:25578322

Lim, Seon-Jeong; Leem, Dong-Seok; Park, Kyung-Bae; Kim, Kyu-Sik; Sul, Sangchul; Na, Kyoungwon; Lee, Gae Hwang; Heo, Chul-Joon; Lee, Kwang-Hee; Bulliard, Xavier; Satoh, Ryu-Ichi; Yagi, Tadao; Ro, Takkyun; Im, Dongmo; Jung, Jungkyu; Lee, Myungwon; Lee, Tae-Yon; Han, Moon Gyu; Jin, Yong Wan; Lee, Sangyoon

2015-01-01

395

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2011 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. ...bismuth citrate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of bismuth citrate in the cosmetic shall not be in excess of 2.0...

2011-04-01

396

21 CFR 73.2110 - Bismuth citrate.  

Code of Federal Regulations, 2010 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2110 Bismuth citrate. ...bismuth citrate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of bismuth citrate in the cosmetic shall not be in excess of 0.5...

2010-04-01

397

ULTRAVIOLET SPECTROPHOTOMETRIC DETERMINATION OF URANIUM. Separation of Uranium from Bismuth Using Tris(2-ethylhexyl)phosphine Oxide. Work completed, May 1958  

Microsoft Academic Search

An ultraviolet spectrophotometric method for the determination of ; uranium was developed which is based on the ultraviolet absorption of the complex ; of uranium(VI) with tris-(2-ethylhexyl)phosphine oxide (TEHPO). The complex is ; formed by extracting unanium(VI) from an aqueous 6M sodium nitrate solution in ; the pH range 2.5to 3.0 into 0.1M solution of TEHPO in an inert diluent,

A. H. A. Heyn; G. Banerjee

1959-01-01

398

High temperature mechanical and oxidation behavior of amorphous silicon carbonitride processed via chemical nanoprecursor route  

NASA Astrophysics Data System (ADS)

Polymer precursor derived ceramics have been studied since last four decades. They promise higher purity and excellent properties with lower processing temperatures in comparison to the traditional route of processing ceramics from powders. The main focus in the literature for polymer derived materials has been on the study of cross linking and pyrolysis of precursors. Relatively fewer reports are available on processing bulk components and property characterization. The polymer precursor determines the nanostructure of the resulting amorphous material and is therefore termed nanoprecursor. In the present dissertation the processing of nanoprecursor to obtain bulk ceramics is studied, with development of an innovative process to fabricate dense defect free materials. The properties of these defect free materials are characterized. Commercially available oligo-ureamethylvinylsilazane (Ceraset(TM)-SN) was used in the present dissertation. The pyrolysis at 1000°C in nitrogen or argon resulted in an amorphous ceramic with chemical composition SiC 0.86N0.82. The specimens obtained by the new process are called cast specimens. Mechanical properties such as flexural strength, hardness, Young s modulus and fracture toughness were determined. The cast specimens showed much better properties as compared to nanoprecursor derived ceramics processed by methods published in the literature. Nanoprecursor derived SiCN show excellent creep resistance at 1350°C at uniaxial stresses ranging from 25--100 MPa. Though a small deformation was measured (~2% in 7 hours), careful analysis showed that this deformation was not creep deformation. The deformation was sintering like, but resulted mainly from the reduction of the activation volume of the amorphous material. The oxidation behavior of the silicon carbonitrides was studied. The material showed passive oxidation, in air at temperature of 1350°C and exhibited parabolic kinetics. Growth rate of the oxidation scale was about a factor of 4 higher than the lowest reported value of CVD Si3N 4 and SiC. Overall the nanoprecursor derived SiCN exhibits excellent thermo-mechanical properties and is a potential candidate for high temperature structural applications.

Shah, Sandeep Rameshchandra

399

Development of silicate and germanate glasses based on lead, bismuth and gallium oxides for midIR microstructured fibers and microoptical elements  

NASA Astrophysics Data System (ADS)

Three component PbO-Bi2O3-Ga2O3 glasses are characterized by high midIR transmittance, with a large susceptibility to crystallization. In this paper we investigate the increase in the thermal stability of these glasses by the addition of oxides such as GeO2, SiO2, Tl2O, CdO, Nb2O5. The resulting multicomponent glasses are well suited for the fabrication of microstructured fibers and micro-optical elements. The increased thermal stability of the modified multi-component glasses resulted in the IR absorption cut-off shifting to shorter wavelengths.

Stepien, Ryszard; Pysz, Dariusz; Kujawa, Ireneusz; Buczynski, Ryszard

2013-06-01

400

Excitation mechanism and thermal emission quenching of Tb ions in silicon rich silicon oxide thin films grown by plasma-enhanced chemical vapour deposition—Do we need silicon nanoclusters?  

SciTech Connect

In this work, we will discuss the excitation and emission properties of Tb ions in a Silicon Rich Silicon Oxide (SRSO) matrix obtained at different technological conditions. By means of electron cyclotron resonance plasma-enhanced chemical vapour deposition, undoped and doped SRSO films have been obtained with different Si content (33, 35, 39, 50 at. %) and were annealed at different temperatures (600, 900, 1100?°C). The samples were characterized optically and structurally using photoluminescence (PL), PL excitation, time resolved PL, absorption, cathodoluminescence, temperature dependent PL, Rutherford backscattering spectrometry, Fourier transform infrared spectroscopy and positron annihilation lifetime spectroscopy. Based on the obtained results, we discuss how the matrix modifications influence excitation and emission properties of Tb ions.

Podhorodecki, A., E-mail: artur.p.podhorodecki@pwr.wroc.pl; Golacki, L. W.; Zatryb, G.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Wang, J.; Jadwisienczak, W. [School of EECS, Ohio University, Stocker Center 363, Athens, Ohio 45701 (United States); Fedus, K. [Institute of Physics, Nicholas Copernicus University, Grudziadzka 5/7, 87-100 Torun (Poland); Wojcik, J.; Wilson, P. R. J.; Mascher, P. [Department of Engineering Physics and Centre for Emerging Device Technologies, McMaster University, 1280 Main St. W, Hamilton, Ontario L8S4L7 (Canada)

2014-04-14

401

A high-speed silicon optical modulator based on a metal-oxide-semiconductor capacitor  

Microsoft Academic Search

Silicon has long been the optimal material for electronics, but it is only relatively recently that it has been considered as a material option for photonics. One of the key limitations for using silicon as a photonic material has been the relatively low speed of silicon optical modulators compared to those fabricated from III-V semiconductor compounds and\\/or electro-optic materials such

Ansheng Liu; Richard Jones; Ling Liao; Dean Samara-Rubio; Doron Rubin; Oded Cohen; Remus Nicolaescu; Mario Paniccia

2004-01-01

402

Effects of silicon nanostructure evolution on Er{sup 3+} luminescence in silicon-rich silicon oxide/Er-doped silica multilayers  

SciTech Connect

The effect of silicon nanostructure evolution on Er{sup 3+} luminescence is investigated by using multilayers of 2.5 nm thin SiO{sub x} (x<2) and 10 nm thin Er-doped silica (SiO{sub 2}:Er). By separating excess Si and Er atoms into separate, nanometer-thin layers, the effect of silicon nanostructure evolution on np-Si sensitized Er{sup 3+} luminescence could be investigated while keeping the microscopic Er{sup 3+} environment the same. The authors find that while the presence of np-Si is necessary for efficient sensitization, the overall quality of np-Si layer has little effect on the Er{sup 3+} luminescence. On the other hand, intrusion of np-Si into Er-doped silica layers leads to deactivation of np-Si/Er{sup 3+} interaction, suggesting that there is a limit to excess Si and Er contents that can be used.

Chang, Jee Soo; Jhe, Ji-Hong; Yang, Moon-Seung; Shin, Jung H.; Kim, Kyung Joong; Moon, Dae Won [Department of Physics, KAIST, 373-1 Guseong-dong, Yuseong-Gu, Daejon 305-701 (Korea, Republic of); Advanced Industrial Metrology Group, KRISS, Daejon 305-600 (Korea, Republic of)

2006-10-30

403

Structural and photoluminescence studies on catalytic growth of silicon/zinc oxide heterostructure nanowires  

PubMed Central

Silicon/zinc oxide (Si/ZnO) core-shell nanowires (NWs) were prepared on a p-type Si(111) substrate using a two-step growth process. First, indium seed-coated Si NWs (In/Si NWs) were synthesized using a plasma-assisted hot-wire chemical vapor deposition technique. This was then followed by the growth of a ZnO nanostructure shell layer using a vapor transport and condensation method. By varying the ZnO growth time from 0.5 to 2 h, different morphologies of ZnO nanostructures, such as ZnO nanoparticles, ZnO shell layer, and ZnO nanorods were grown on the In/Si NWs. The In seeds were believed to act as centers to attract the ZnO molecule vapors, further inducing the lateral growth of ZnO nanorods from the Si/ZnO core-shell NWs via a vapor-liquid-solid mechanism. The ZnO nanorods had a tendency to grow in the direction of [0001] as indicated by X-ray diffraction and high resolution transmission electron microscopy analyses. We showed that the Si/ZnO core-shell NWs exhibit a broad visible emission ranging from 400 to 750 nm due to the combination of emissions from oxygen vacancies in ZnO and In2O3 structures and nanocrystallite Si on the Si NWs. The hierarchical growth of straight ZnO nanorods on the core-shell NWs eventually reduced the defect (green) emission and enhanced the near band edge (ultraviolet) emission of the ZnO. PMID:23590803

2013-01-01

404

Sponge-like Si-SiO{sub 2} nanocomposite—Morphology studies of spinodally decomposed silicon-rich oxide  

SciTech Connect

Sponge-like Si nanostructures embedded in SiO{sub 2} were fabricated by spinodal decomposition of sputter-deposited silicon-rich oxide with a stoichiometry close to that of silicon monoxide. After thermal treatment a mean feature size of about 3 nm was found in the phase-separated structure. The structure of the Si-SiO{sub 2} nanocomposite was investigated by energy-filtered transmission electron microscopy (EFTEM), EFTEM tomography, and atom probe tomography, which revealed a percolated Si morphology. It was shown that the percolation of the Si network in 3D can also be proven on the basis of 2D EFTEM images by comparison with 3D kinetic Monte Carlo simulations.

Friedrich, D.; Schmidt, B.; Heinig, K. H.; Liedke, B.; Mücklich, A.; Hübner, R. [Helmholtz-Zentrum Dresden – Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany)] [Helmholtz-Zentrum Dresden – Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Wolf, D. [Triebenberg Laboratory, Institute of Structure Physics, Technische Universität Dresden, 01062 Dresden (Germany)] [Triebenberg Laboratory, Institute of Structure Physics, Technische Universität Dresden, 01062 Dresden (Germany); Kölling, S. [Fraunhofer Center Nanoelectronic Technologies, Königsbrücker Str. 180, 01099 Dresden (Germany)] [Fraunhofer Center Nanoelectronic Technologies, Königsbrücker Str. 180, 01099 Dresden (Germany); Mikolajick, T. [NaMLab GmbH, Nöthnitzer Str. 64, 01187 Dresden (Germany) [NaMLab GmbH, Nöthnitzer Str. 64, 01187 Dresden (Germany); Technische Universität Dresden, Nöthnitzer Str. 64, 01187 Dresden (Germany)

2013-09-23

405

Thickness-dependent optimization of Er3+ light emission from silicon-rich silicon oxide thin films  

PubMed Central

This study investigates the influence of the film thickness on the silicon-excess-mediated sensitization of Erbium ions in Si-rich silica. The Er3+ photoluminescence at 1.5 ?m, normalized to the film thickness, was found five times larger for films 1 ?m-thick than that from 50-nm-thick films intended for electrically driven devices. The origin of this difference is shared by changes in the local density of optical states and depth-dependent interferences, and by limited formation of Si-based sensitizers in "thin" films, probably because of the prevailing high stress. More Si excess has significantly increased the emission from "thin" films, up to ten times. This paves the way to the realization of highly efficient electrically excited devices. PMID:21711930

2011-01-01

406

Controlling Er-Tm interaction in Er and Tm codoped silicon-rich silicon oxide using nanometer-scale spatial separation for efficient, broadband infrared luminescence  

SciTech Connect

The effect of nanometer-scale spatial separation between Er{sup 3+} and Tm{sup 3+} ions in Er and Tm codoped silicon-rich silicon oxide (SRSO) films is investigated. Er and Tm codoped SRSO films, which consist of nanocluster Si (nc-Si) embedded inside SiO{sub 2} matrix, were fabricated with electron cyclotron resonance-plasma enhanced chemical vapor deposition of SiH{sub 4} and O{sub 2} with concurrent sputtering of Er and Tm metal targets. Spatial separation between Er{sup 3+} and Tm{sup 3+} ions was achieved by depositing alternating layers of Er- and Tm-doped layers of varying thickness while keeping the total film thickness the same. The films display broadband infrared photoluminescence (PL) from 1.5 to 2.0 {mu}m under a single source excitation due to simultaneous excitation of Er{sup 3+} and Tm{sup 3+} ions by nc-Si. Increasing the layer thickness from 0 to 72 nm increases the Er{sup 3+} PL intensity nearly 50-fold while the Tm{sup 3+} PL intensity is unaffected. The data are well-explained by a model assuming a dipole-dipole interaction between excited Er{sup 3+} and Tm{sup 3+} ions, and suggest that by nanoscale engineering, efficient, ultrabroadband infrared luminescence can be obtained in an optically homogeneous material using a single light source.

Seo, Se-Young; Shin, Jung H. [Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejon (Korea, Republic of)

2004-11-01

407

The silicon/zinc oxide interface in amorphous silicon-based thin-film solar cells: Understanding an empirically optimized contact  

SciTech Connect

The electronic structure of the interface between the boron-doped oxygenated amorphous silicon 'window layer' (a-SiO{sub x}:H(B)) and aluminum-doped zinc oxide (ZnO:Al) was investigated using hard x-ray photoelectron spectroscopy and compared to that of the boron-doped microcrystalline silicon ({mu}c-Si:H(B))/ZnO:Al interface. The corresponding valence band offsets have been determined to be (-2.87 {+-} 0.27) eV and (-3.37 {+-} 0.27) eV, respectively. A lower tunnel junction barrier height at the {mu}c-Si:H(B)/ZnO:Al interface compared to that at the a-SiO{sub x}:H(B)/ZnO:Al interface is found and linked to the higher device performances in cells where a {mu}c-Si:H(B) buffer between the a-Si:H p-i-n absorber stack and the ZnO:Al contact is employed.

Gerlach, D.; Wilks, R. G.; Wimmer, M.; Felix, R.; Gorgoi, M.; Lips, K.; Rech, B. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Wippler, D.; Mueck, A.; Meier, M.; Huepkes, J. [Institut fuer Energie- und Klimaforschung, Forschungszentrum Juelich GmbH, Wilhelm-Johnen-Strasse, D-52428 Juelich (Germany); Lozac'h, M.; Ueda, S.; Sumiya, M. [National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Yoshikawa, H. [Synchrotron X-ray Station at SPring-8, NIMS, Kouto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Kobayashi, K. [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Kouto 1-1-1, SPring-8, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Baer, M. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Institut fuer Physik und Chemie, Brandenburgische Technische Universitaet Cottbus, Konrad-Wachsmann-Allee 1, D-03046 Cottbus (Germany)

2013-07-08

408

Nano Structural Properties of Bismuth  

E-print Network

Abstract: In the last decade, some low-index surfaces of the group V semimetal bismuth have been studied due to their special geometric and electronic structures which including the effect of the interband transition, spin-orbit interaction, (and perhaps, the ad-, rest-and corner-atoms on their surface) and on the electron-phonon coupling. The surface geometric structure of bismuth is more sensitive to incoming atoms and the reconstructions on the surface respect to the bulk structure. This point causes that the surface shows considerably better metallic behavior than that the bulk. We have thus considered XRD (X-Ray Diffraction) spectrum and the spin-orbit coupling for studying the surface electronic structure of Bi. The obtained results indicate that there are strong splitting phenomena at surface state bands due to the loss of symmetry at the surface. Key words: Nanomaterial Nanostructure XRD and Bismuth INTRODUCTION Although quantitatively identifying different contributions of the nanostructures to the transport Solid state physics is a term used to describe physics properties is not possible at this stage, we believe that the involving solid matter and the phenomena that occur in nanostructures and imperfections scatter all phonons with crystals consisting of millions of atoms. Bismuth has been mean free paths from the micron scale down to the atomic

A. Bahari; M. Zokai

409

Surface morphology of cellulose films prepared by spin coating on silicon oxide substrates pretreated with cationic polyelectrolyte  

NASA Astrophysics Data System (ADS)

Flat cellulose films were prepared and morphologically modified by spin coating a cellulose/ N-methylmorpholine- N-oxide/H 2O solution onto silicon oxide substrates pre-coated with a cationic polyelectrolyte. Spin-coated cellulose films were allowed to stably form on the silicon oxide substrates by pretreatment with either polydiallyldimethylammonium chloride (PDADMAC) or polyvinylamine (PVAm). The film surfaces obtained were analyzed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). AFM topographical images of the cellulose film surfaces showed a different morphology depending on the underlying polymer, where PVAm pretreatment brought about an anisotropic surface topology. These results suggest that the specific attraction acting at the cellulose/polymer interface influences both the film formation and surface morphology of the cellulose layer. Differences in the solvent used to precipitate cellulose caused variations in the surface roughness by affecting the cellulose separation behavior. The morphological features of spin-coated cellulose film surfaces could be altered to some extent by these film preparation techniques.

Yokota, Shingo; Kitaoka, Takuya; Wariishi, Hiroyuki

2007-02-01

410

Study of the use of Metal-Oxide-Silicon (MOS) devices for particulate detection and monitoring in the earth's atmosphere  

NASA Technical Reports Server (NTRS)

A metal-oxide-silicon (MOS) capacitor-type particulate sensor was evaluated for use in atmospheric measurements. An accelerator system was designed and tested for the purpose of providing the necessary energy to trigger the MOS-type sensor. The accelerator system and the MOS sensor were characterized as a function of particle size and velocity. Diamond particles were used as particulate sources in laboratory tests. Preliminary tests were performed in which the detector was mounted on an aircraft and flown in the vicinity of coal-fired electric generating plants.

Brooks, A. D.; Monteith, L. K.; Wortman, J. J.; Mulligan, J. C.

1974-01-01

411

Wettability effect of graphene-based surfaces on silicon carbide and their influence on hydrophobicity of nanocrystalline cerium oxide films.  

PubMed

We investigate the water-repellent ability of graphene-based surfaces stabilized on silicon carbide (SiC) and the nanocrystalline cerium oxide (CeO2) films electrodeposited on them. Water contact angle is revealed strongly dependent on the number of graphene monolayers on SiC, indicating partial permeability of graphene on SiC. Fluctuations in the roughness of textured surfaces as well as variations of oxygen vacancy content in CeO2 electrodeposits are determinant for the hydrophobicity of the interaction between water droplets and nanocrystalline CeO2 electrodeposits on monolayers graphene on SiC. PMID:25490565

Souza, Jean C; Neckel, Itamar T; Varalda, Jose; Ribeiro, Evaldo; Schreiner, Wido H; Mosca, Dante H; Sierakowski, Maria-Rita; Fernandes, Vilmar; Ouerghi, Abdelkarim

2015-03-01

412

Low-power bacteriorhodopsin-silicon n-channel metal-oxide field-effect transistor photoreceiver.  

PubMed

A bacteriorhodopsin (bR)-silicon n-channel metal-oxide field-effect transistor (NMOSFET) monolithically integrated photoreceiver is demonstrated. The bR film is selectively formed on an external gate electrode of the transistor by electrophoretic deposition. A modified biasing circuit is incorporated, which helps to match the resistance of the bR film to the input impedance of the NMOSFET and to shift the operating point of the transistor to coincide with the maximum gain. The photoreceiver exhibits a responsivity of 4.7 mA/W. PMID:17392901

Shin, Jonghyun; Bhattacharya, Pallab; Yuan, Hao-Chih; Ma, Zhenqiang; Váró, György

2007-03-01

413

Critical oxide thickness for efficient single-walled carbon nanotube growth on silicon using thin SiO2 diffusion barriers  

Microsoft Academic Search

The ability to integrate carbon nanotubes, especially single-walled carbon nanotubes, seamlessly onto silicon would expand their range of applications considerably. Though direct integration using chemical vapor deposition is the simplest method, the growth of single-walled carbon nanotubes on bare silicon and on ultrathin oxides is greatly inhibited due to the formation of a noncatalytic silicide. Using X-ray photoelectron spectroscopy, we

Robert J. Hamers

2006-01-01

414

21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 false Kanamycin, bismuth subcarbonate, activated attapulgite...ANIMAL DRUGS § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite...kanamycin (as the sulfate), 250 mg bismuth subcarbonate, and 500 mg activated...

2013-04-01

415

21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 false Kanamycin, bismuth subcarbonate, activated attapulgite...ANIMAL DRUGS § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite...kanamycin (as the sulfate), 250 mg bismuth subcarbonate, and 500 mg activated...

2012-04-01

416

21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 false Kanamycin, bismuth subcarbonate, activated attapulgite...ANIMAL DRUGS § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite...kanamycin (as the sulfate), 250 mg bismuth subcarbonate, and 500 mg activated...

2010-04-01

417

21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 false Kanamycin, bismuth subcarbonate, activated attapulgite...ANIMAL DRUGS § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite...kanamycin (as the sulfate), 250 mg bismuth subcarbonate, and 500 mg activated...

2011-04-01

418

Exfoliation and Characterization of Bismuth Telluride Atomic Quintuples and  

E-print Network

Exfoliation and Characterization of Bismuth Telluride Atomic Quintuples and Quasi, University of CaliforniasRiverside, Riverside, California 92521 ABSTRACT Bismuth telluride (Bi2Te3) and its describe a method for "graphene-inspired" exfoliation of crystalline bismuth telluride films

419

21 CFR 520.1204 - Kanamycin, bismuth subcarbonate, activated attapulgite.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 false Kanamycin, bismuth subcarbonate, activated attapulgite...ANIMAL DRUGS § 520.1204 Kanamycin, bismuth subcarbonate, activated attapulgite...kanamycin (as the sulfate), 250 mg bismuth subcarbonate, and 500 mg activated...

2014-04-01

420

Surface Area, and Oxidation Effects on Nitridation Kinetics of Silicon Powder Compacts  

NASA Technical Reports Server (NTRS)

Commercially available silicon powders were wet-attrition-milled from 2 to 48 hr to achieve surface areas (SA's) ranging from 1.3 to 70 sq m/g. The surface area effects on the nitridation kinetics of silicon powder compacts were determined at 1250 or 1350 C for 4 hr. In addition, the influence of nitridation environment, and preoxidation on nitridation kinetics of a silicon powder of high surface area (approximately equals 63 sq m/g) was investigated. As the surface area increased, so did the percentage nitridation after 4 hr in N2 at 1250 or 1350 C. Silicon powders of high surface area (greater than 40 sq m/g) can be nitrided to greater than 70% at 1250 C in 4 hr. The nitridation kinetics of the high-surface-area powder compacts were significantly delayed by preoxidation treatment. Conversely, the nitridation environment had no significant influence on the nitridation kinetics of the same powder. Impurities present in the starting powder, and those accumulated during attrition milling, appeared to react with the silica layer on the surface of silicon particles to form a molten silicate layer, which provided a path for rapid diffusion of nitrogen and enhanced the nitridation kinetics of high surface area silicon powder.

Bhatt, R. T.; Palczer, A. R.

1998-01-01

421

One-step Melt Synthesis of Water Soluble, Photoluminescent, Surface-Oxidized Silicon Nanoparticles for Cellular Imaging Applications  

PubMed Central

We have developed a versatile, one-step melt synthesis of water-soluble, highly emissive silicon nanoparticles using bi-functional, low-melting solids (such as glutaric acid) as reaction media. Characterization through transmission electron microscopy, selected area electron diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy shows that the one-step melt synthesis produces nanoscale Si cores surrounded by a silicon oxide shell. Analysis of the nanoparticle surface using FT-IR, zeta potential, and gel electrophoresis indicates that the bi-functional ligand used in the one-step synthesis is grafted onto the nanoparticle, which allows for tuning of the particle surface charge, solubility, and functionality. Photoluminescence spectra of the as-prepared glutaric acid-synthesized silicon nanoparticles show an intense blue-green emission with a short (ns) lifetime suitable for biological imaging. These nanoparticles are found to be stable in biological media and have been used to examine cellular uptake and distribution in live N2a cells. PMID:23139440

Manhat, Beth A.; Brown, Anna L.; Black, Labe A.; Ross, J.B. Alexander; Fichter, Katye; Vu, Tania; Richman, Erik

2012-01-01

422

Determination of silicon in biological samples by ICP-OES after non-oxidative decomposition under alkaline conditions.  

PubMed

A non-oxidative alkaline sample digestion procedure using tetramethylammonium hydroxide and a high pressure, microwave assisted autoclave digestion system was developed. The silicon concentrations of the digested samples were measured by inductively coupled axial plasma optical emission spectrometry (ICP-OES). Details of the digestion conditions as well as the optimised instrumental parameters for ICP-OES are described. The method was developed and tested using silicon-spiked ascorbic acid and applied to samples of animal tissue and organs. The total silicon content of two different reference materials, NIST 1577b Bovine liver and BCR 184 Bovine Muscle having neither certified nor informational values for Si was determined. The results obtained are compared with the results of independent methods such as wavelength dispersive x-ray fluorescence spectrometry (WDXRF) and solid sampling electrothermal atomic absorption spectrometry (ETAAS). The method described achieves a limit of detection of 2 mg kg(-1) using 100 mg of solid biological or organic material and covers a concentration range of up to 500 mg kg(-1). PMID:11451245

Hauptkorn, S; Pavel, J; Seltner, H

2001-06-01

423

Formation and characterization of porous silicon-samarium/gadolinium nanocomposites: effect of substrate oxidation and biosynthesis process  

NASA Astrophysics Data System (ADS)

Samarium and gadolinium nanoparticles synthesized by bioreduction process have been incorporated into nanostructured porous silicon template to form a nanocomposite. The structural and optical properties of PS-Gd and PS-Sm nanocomposites have been studied through TEM, SEM and UV-Vis spectroscopy. Extent of infiltration has been verified through reflectance interference Fourier transform spectroscopy as a function of substrate oxidation conditions. The substrates oxidized at 600 °C showed the maximum infiltration and the corresponding change of optical thickness due to nanoparticles. Such biodegradable nanocomposites in the form of particles can have potential applications in localized drug delivery and enhancement of the image contrast and optoelectronic devices. The results here reported open an energy-cheap procedure to take advantages of small rare earth nanoparticles and produced nanocomposites with their immersion in SiO2 substrates, with the perspective to be replied in other similar substrates under controlled conditions.

Perdigon-Lagunes, P.; Ascencio, J. A.; Agarwal, V.

2014-12-01

424

Oxygen impurity effects at metal/silicide interfaces - Formation of silicon oxide and suboxides in the Ni/Si system  

NASA Technical Reports Server (NTRS)

The effect of implanted oxygen impurities on the Ni/Ni2Si interface is investigated using X-ray photoelectron spectroscopy, He-4(+) backscattering and O(d, alpha)-16 N-14 nuclear reactions. Oxygen dosages corresponding to concentrations of 1, 2, and 3 atomic percent were implanted into Ni films evaporated on Si substrates. The oxygen, nickel, and silicon core lines were monitored as a function of time during in situ growth of the Ni silicide to determine the chemical nature of the diffusion barrier which forms in the presence of oxygen impurities. Analysis of the Ni, Si, and O core levels demonstrates that the formation of SiO2 is responsible for the Ni diffusion barrier rather than Ni oxide or mixed oxides, such as Ni2SiO4. It is determined that 2.2 x 10 to the 16th O/qu cm is sufficient to prevent Ni diffusion under UHV annealing conditions.

Grunthaner, P. J.; Grunthaner, F. J.; Scott, D. M.; Nicolet, M.-A.; Mayer, J. W.

1981-01-01

425

Photoreductive generation of amorphous bismuth nanoparticles using polysaccharides--bismuth-cellulose nanocomposites.  

PubMed

A simple and highly reproducible synthesis of amorphous bismuth nanoparticles incorporated into a polysaccharide matrix using a photoreduction process is presented. As precursor for the generation of the Bi nanoparticles, organosoluble triphenylbismuth is used. The precursor is dissolved in toluene and mixed with a hydrophobic organosoluble polysaccharide, namely trimethylsilyl cellulose (TMSC) with high DSSi. The solution is subjected to UV exposure, which induces the homolytic cleavage of the bismuth-carbon bond in BiPh3 resulting in the formation of Bi(0) and phenyl radicals. The aggregation of the Bi atoms can be controlled in the TMSC matrix and yields nanoparticles of around 20 nm size as proven by TEM. The phenyl radicals undergo recombination to form small organic molecules like benzene and biphenyl, which can be removed from the nanocomposite after lyophilization and exposure to high vacuum. Finally, the TMSC matrix is converted to cellulose after exposure to HCl vapors, which remove the trimethylsilyl groups from the TMSC derivative. Although TMSC is converted to cellulose, the formed TMS-OH is not leaving the nanocomposite but reacts instead with surface oxide layer of the Bi nanoparticles to form silylated Bi nanoparticles as proven by TEM/EDX. PMID:25458299

Breitwieser, Doris; Kriechbaum, Margit; Ehmann, Heike M A; Monkowius, Uwe; Coseri, Sergiu; Sacarescu, Liviu; Spirk, Stefan

2015-02-13

426

Structural and oxidative changes in the kidney of crucian carp induced by silicon-based quantum dots.  

PubMed

Silicon-based quantum dots were intraperitoneally injected in Carassius auratus gibelio specimens and, over one week, the effects on renal tissue were investigated by following their distribution and histological effects, as well as antioxidative system modifications. After three and seven days, detached epithelial cells from the basal lamina, dilated tubules and debris in the lumen of tubules were observed. At day 7, nephrogenesis was noticed. The reduced glutathione (GSH) concentration decreased in the first three days and started to rise later on. The superoxide dismutase (SOD) activity increased only after one week, whereas catalase (CAT) was up-regulated in a time-dependent manner. The activities of glutathione reductase (GR) and glutathione peroxidise (GPX) decreased dramatically by approximately 50% compared to control, whereas the glutathione-S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH) increased significantly after 3 and 7 days of treatment. Oxidative modifications of proteins and the time-dependent increase of Hsp70 expression were also registered. Our data suggest that silicon-based quantum dots induced oxidative stress followed by structural damages. However, renal tissue is capable of restoring its integrity by nephron development. PMID:22949855

Petrache, Sorina Nicoleta; Stanca, Loredana; Serban, Andreea Iren; Sima, Cornelia; Staicu, Andreia Cristina; Munteanu, Maria Cristina; Costache, Marieta; Burlacu, Radu; Zarnescu, Otilia; Dinischiotu, Anca

2012-01-01

427

Structural and Oxidative Changes in the Kidney of Crucian Carp Induced by Silicon-Based Quantum Dots  

PubMed Central

Silicon-based quantum dots were intraperitoneally injected in Carassius auratus gibelio specimens and, over one week, the effects on renal tissue were investigated by following their distribution and histological effects, as well as antioxidative system modifications. After three and seven days, detached epithelial cells from the basal lamina, dilated tubules and debris in the lumen of tubules were observed. At day 7, nephrogenesis was noticed. The reduced glutathione (GSH) concentration decreased in the first three days and started to rise later on. The superoxide dismutase (SOD) activity increased only after one week, whereas catalase (CAT) was up-regulated in a time-dependent manner. The activities of glutathione reductase (GR) and glutathione peroxidise (GPX) decreased dramatically by approximately 50% compared to control, whereas the glutathione-S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH) increased significantly after 3 and 7 days of treatment. Oxidative modifications of proteins and the time-dependent increase of Hsp70 expression were also registered. Our data suggest that silicon-based quantum dots induced oxidative stress followed by structural damages. However, renal tissue is capable of restoring its integrity by nephron development. PMID:22949855

Petrache, Sorina Nicoleta; Stanca, Loredana; Serban, Andreea Iren; Sima, Cornelia; Staicu, Andreia Cristina; Munteanu, Maria Cristina; Costache, Marieta; Burlacu, Radu; Zarnescu, Otilia; Dinischiotu, Anca

2012-01-01

428

Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates  

DOEpatents

A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

Sarin, Vinod K. (Lexington, MA)

1991-01-01

429

Index of refraction versus oxygen partial pressure for tantalum oxide and silicon dioxide films produced by ion beam deposition  

SciTech Connect

Tantalum oxide and silicon oxide films were made using an ion beam sputtering system. It was found that even though these films were deposited from oxide targets, additions of oxygen were necessary to achieve stoichiometry and hence index of refraction. It was observed that the tantalum oxide target changed color from white to gray, indicating that the oxygen was being depleted from the target. The addition of oxygen to the chamber during deposition replenished the target and improved film stoichiometry. The deposition rate decreased with increasing oxygen partial pressure. It was experimentally determined that by varying the oxygen partial pressure and keeping all other variables fixed, the index of refraction of the film changed in a predictable manner. That is, as the oxygen partial pressure was increased, the index decreased rapidly initially and then reached a saturation point where it stayed fixed with oxygen content. With this data a coating process can be set up using the minimum amount of oxygen (thus increasing filament lifetime) to produce a fully stoichiometric film that has a fixed index. This paper will present the details of these observations and results.

Goward, W.D.; Petersen, H.E.; Dijaili, S.P.; Walker, J.D.

1998-04-30

430

Substitution effects on bismuth based multifunctional materials  

NASA Astrophysics Data System (ADS)

Described are our targeted experiments to improve understanding of some key aspects of the mechanisms contributing to intrinsic effects such as the magnetoelectric coupling in oxides. The magnetoelectric materials have long been of interest because of useful combinations of electrical, magnetic, optical and catalytic properties. Particularly spectacular are the manganites(M=Mn) for which apart from the strong magnetoresistance (MR) effect another striking feature is the occurrence of charge and orbital ordering (CO-OO) effects connected with the specific orbital orientation and the spatial arrangement of the eg orbitals. The MR and CO-OO effects are a manifestation of the strong interplay between the orbital, charge, and spin degrees of freedom in these systems and in some cases gives rise to multiferroicity. In this regard, some of our research is on new ABO3, AB2O5 and double perovskites A2BB'O6 containing p elements with lone pair electrons such as Bi3+. Bismuth creates irregular oxygen coordination environment and to stabilize its valence state often requires the use of high pressure or specific soft chemistry. Studied are the effects of cationic substitution on the structural parameters of the perovskites (Bi1-yRy)1-xAxMnO3 (R = rare earth; A= Ca2+, Sr2+; x,y=0.5), BiFexMn2-xO5, La1-xBiXMn2O5 etc. Ab-initio density functional theory calculations were performed to study the structure, magnetic and optical properties of multiferroic BiFeO3, also modified with La3+ and Mn3+. Synthesized and characterized is a new bismuth oxide - multiferroic BiFe2O5-? A number of studies continue to address this class of materials and related-type materials such as cobaltites, chromites and ferrites, much of the work being driven by the potential applications as electrode materials in solid oxide fuel cells, exhaust gas sensors, membranes for separation processes or as catalysts but lately new functionalities emerge and are in the focus for use in electronics and information storage capabilities.

Krezhov, Kiril; Kovachev, Stefan; Svab, Erzsebet

431

Fluorine-implanted bismuth oxide superconductors  

SciTech Connect

We report for the first time the influence of fluorine implantation in the Bi-Sr-Ca-Cu-O system. The incorporation of fluorine was found to enhance the zero resistance temperature and to sharpen the high-temperature transition. The fluorinated sample exhibited T/sub c/ (R = 0) = 89 K and the high T/sub c/ phase of the composition had T/sub c/ (on) as high as 124 K with an extrapolated T/sub c/ (end) of 114 K. Resistance temperature characteristics of a sample before and after fluorine implantation are presented.

Gupta, R.P.; Khokle, W.S.; Pachauri, J.P.; Tripathi, C.C.; Pathak, B.C.; Virdi, G.S.

1989-02-06

432

A simultaneously diffused, textured, in situ oxide AR-coated solar cell process (STAR process) for high-efficiency silicon solar cells  

Microsoft Academic Search

A novel device fabrication process called the STAR process is presented, which incorporates a Simultaneously diffused emitter and Back Surface Field (BSF), on a textured silicon wafer, with an in situ thermal oxide for surface passivation and Anti-Reflection (AR) coating. In a single high-temperature step, the STAR process provides four important quality-enhancement features: (1) emitter oxide passivation, (2) back surface

Thomas Krygowski; Ajeet Rohatgi

1998-01-01

433

Light-induced water oxidation at silicon electrodes functionalized with a cobalt oxygen-evolving catalyst  

E-print Network

Integrating a silicon solar cell with a recently developed cobalt-based water-splitting catalyst (Co-Pi) yields a robust, monolithic, photo-assisted anode for the solar fuels process of water splitting to O2 at neutral pH. ...

Pijpers, Joep J. H.

434

Sequential separation of neptunium, plutonium, americium and curium using coprecipitation with bismuth phosphate  

Microsoft Academic Search

The reaction of neptunium, plutonium and americium with oxidizing or reducing agents in phosphoric acid solution has been studied to design a separation procedure of the actinide elements using coprecipitation with bismuth phosphate. In the presence of uranium, successive separation of neptunium, plutonium, americium and curium was accomplished by combining the coprecipitation and redox reaction of the elements. The coprecipitation

T. Kimura

1990-01-01

435

Bismuth-based optical fiber with nonlinear coefficient of 1360 W-1km-1  

Microsoft Academic Search

Abstract: We ,developed ,a conventional ,step-index type highly nonlinear bismuth ,oxide-based glass fiber. This ,fiber exhibits high nonlinearity (? =1360 W, [4]. This ,high nonlinearity originates from high nonlinearity of Bi2O3-based glass [5]. In addition to the high nonlinearity, this fiber shows relatively low propagation loss less

N. Sugimoto; T. Nagashima; T. Hasegawa; S. Ohara; K. Taira; K. Kikuchi

436

Bis(tri-n-hexylsilyl oxide) silicon phthalocyanine: a unique additive in ternary bulk heterojunction organic photovoltaic devices.  

PubMed

Previous studies have shown that the use of bis(tri-n-hexylsilyl oxide) silicon phthalocyanine ((3HS)2-SiPc) as an additive in a P3HT:PC61BM cascade ternary bulk heterojunction organic photovoltaic (BHJ OPV) device results in an increase in the short circuit current (J(SC)) and efficiency (?(eff)) of up to 25% and 20%, respectively. The previous studies have attributed the increase in performance to the presence of (3HS)2-SiPc at the BHJ interface. In this study, we explored the molecular characteristics of (3HS)2-SiPc which makes it so effective in increasing the OPV device J(SC) and ?(eff. Initially, we synthesized phthalocyanine-based additives using different core elements such as germanium and boron instead of silicon, each having similar frontier orbital energies compared to (3HS)2-SiPc and tested their effect on BHJ OPV device performance. We observed that addition of bis(tri-n-hexylsilyl oxide) germanium phthalocyanine ((3HS)2-GePc) or tri-n-hexylsilyl oxide boron subphthalocyanine (3HS-BsubPc) resulted in a nonstatistically significant increase in JSC and ?(eff). Secondly, we kept the silicon phthalocyanine core and substituted the tri-n-hexylsilyl solubilizing groups with pentadecyl phenoxy groups and tested the resulting dye in a BHJ OPV. While an increase in JSC and ?(eff) was observed at low (PDP)2-SiPc loadings, the increase was not as significant as (3HS)2-SiPc; therefore, (3HS)2-SiPc is a unique additive. During our study, we observed that (3HS)2-SiPc had an extraordinary tendency to crystallize compared to the other compounds in this study and our general experience. On the basis of this observation, we have offered a hypothesis that when (3HS)2-SiPc migrates to the P3HT:PC61BM interface the reason for its unique performance is not solely due to its frontier orbital energies but also might be due to a high driving force for crystallization. PMID:25105425

Lessard, Benoît H; Dang, Jeremy D; Grant, Trevor M; Gao, Dong; Seferos, Dwight S; Bender, Timothy P

2014-09-10

437

Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface  

SciTech Connect

Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important.

Nichau, A.; Schnee, M.; Schubert, J.; Bernardy, P.; Hollaender, B.; Buca, D.; Mantl, S. [Peter Gruenberg Institute 9 (PGI9-IT), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technologies, 52425 Juelich (Germany); Besmehn, A.; Breuer, U. [Central Division for Chemical Analysis (ZCH), Forschungszentrum Juelich, 52425 Juelich (Germany); Rubio-Zuazo, J.; Castro, G. R. [Spanish CRG BM25 Beamline-SpLine, European Synchrotron Radiation Facility (ESRF), Rue Jules Horowitz BP 220, F-38043 Grenoble, Cedex 09 (France); Muecklich, A.; Borany, J. von [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum' Dresden-Rossendorf e.V., 01314 Dresden (Germany)

2013-04-21

438

Oxidation kinetics of chemically vapor-deposited silicon carbide in wet oxygen  

Microsoft Academic Search

The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen at temperatures between 1,200 and 1,400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the

Elizabeth J. Opila

1994-01-01

439

Influence of Alumina Reaction Tube Impurities on the Oxidation of Chemically-Vapor-Deposited Silicon Carbide  

NASA Technical Reports Server (NTRS)

Pure coupons of chemically vapor deposited (CVD) SiC were oxidized for 100 h in dry flowing oxygen at 1300 C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes. The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences were attributed to impurities in the alumina tubes. Investigators interested in high-temperature oxidation of silica formers should be aware that high-purity alumina can have significant effects on experiment results.

Opila, Elizabeth

1995-01-01

440

Intersubband transitions in bismuth nanowires M. R. Blacka)  

E-print Network

Intersubband transitions in bismuth nanowires M. R. Blacka) Department of Electrical Engineering of an intersubband transition in bismuth nanowires is reported. The previously observed strong absorption in bismuth transitions in bismuth nanowires as a way of building this understanding. When the sample size is smaller than

Cronin, Steve

441

Electrical and elastoresistance properties of evaporated thin films of bismuth  

E-print Network

405 Electrical and elastoresistance properties of evaporated thin films of bismuth M. Saleh, J pour rendre les couches de bismuth utilisables en tant que jauges de contrainte n'apporte aucune modification majeure des propriétés électriques du bismuth si on les compare à celles des couches de bismuth

Boyer, Edmond

442

Electronic Properties of Bismuth Nanowires Stephen B. Cronina  

E-print Network

Electronic Properties of Bismuth Nanowires Stephen B. Cronina , Yu-Ming Linb , Oded Rabinc , Marcie alumina templates with molten bismuth has been used to synthesize single crystalline bismuth nanowires. INTRODUCTION Bismuth is an interesting material to study on the nanoscale because bulk Bi has very small

Cronin, Steve

443

Optical spectroscopy of bismuth-doped pure silica fiber preform  

E-print Network

Optical spectroscopy of bismuth-doped pure silica fiber preform I. Razdobreev,1,2, * H. El Hamzaoui on the optical spectroscopy of monolithic fiber preform prepared from nanoporous bismuth-doped silica glass connected to Bismuth. © 2010 Optical Society of America OCIS codes: 140.3510, 140.3380, 300.6250. Bismuth

Boyer, Edmond

444

Modification of optical and electrical properties of zinc oxide-coated porous silicon nanostructures induced by swift heavy ion  

PubMed Central

Morphological and optical characteristics of radio frequency-sputtered zinc aluminum oxide over porous silicon (PS) substrates were studied before and after irradiating composite films with 130?MeV of nickel ions at different fluences varying from 1?×?1012 to 3?×?1013 ions/cm2. The effect of irradiation on the composite structure was investigated by scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), and cathodoluminescence spectroscopy. Current–voltage characteristics of ZnO-PS heterojunctions were also measured. As compared to the granular crystallites of zinc oxide layer, Al-doped zinc oxide (ZnO) layer showed a flaky structure. The PL spectrum of the pristine composite structure consists of the emission from the ZnO layer as well as the near-infrared emission from the PS substrate. Due to an increase in the number of deep-level defects, possibly oxygen vacancies after swift ion irradiation, PS-Al-doped ZnO nanocomposites formed with high-porosity PS are shown to demonstrate a broadening in the PL emission band, leading to the white light emission. The broadening effect is found to increase with an increase in the ion fluence and porosity. XRD study revealed the relative resistance of the film against the irradiation, i.e., the irradiation of the structure failed to completely amorphize the structure, suggesting its possible application in optoelectronics and sensing applications under harsh radiation conditions. PMID:22748164

2012-01-01

445

Surface contamination and damage from CF4 and SF6 reactive ion etching of silicon oxide on gallium arsenide  

NASA Astrophysics Data System (ADS)

Two reactive ion etchants, CF4 and SF6, have been compared in terms of plasma characteristics, silicon oxide etch characteristics, extent of RIE damage, and formation of barrier layers on a GaAs surface after oxide etch. It was found that higher etch rates with lower plasma-induced dc bias can be achieved with SF6 plasma relative to CF4 plasma and that this correlates with higher atomic fluorine concentration in SF6 plasma. RIE damage, measured by loss of sheet conductance in a thin highly-doped GaAs layer, could be modelled as a region of deep acceptors at a high concentration in the conductive layer. By relating the sheet conductance change to the modelled damaged layer thickness, it was found that the RIE-damaged thickness from both CF4 and SF6 plasmas had the same linear relation to plasma dc bias. Barriers to subsequent GaAs RIE were created during oxide overetch at the GaAs surface. The barriers were identified by XPS as ˜20 A of GaF3 for CF4 plasma and ˜30 A of GaF3 on top of AsxSy for SF6 plasma. Ellipsometry was used to routinely determine the presence or absence of the barriers which could be removed in dilute ammonia.

Seaward, K. L.; Moll, N. J.; Stickle, W. F.

1990-04-01

446

A silicon nanowire-reduced graphene oxide composite as a high-performance lithium ion battery anode material.  

PubMed

Toward the increasing demands of portable energy storage and electric vehicle applications, silicon has been emerging as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, serious pulverization of bulk silicon during cycling limits its cycle life. Herein, we report a novel hierarchical Si nanowire (Si NW)-reduced graphene oxide (rGO) composite fabricated using a solvothermal method followed by a chemical vapor deposition process. In the composite, the uniform-sized [111]-oriented Si NWs are well dispersed on the rGO surface and in between rGO sheets. The flexible rGO enables us to maintain the structural integrity and to provide a continuous conductive network of the electrode, which results in over 100 cycles serving as an anode in half cells at a high lithium storage capacity of 2300 mA h g(-1). Due to its [111] growth direction and the large contact area with rGO, the Si NWs in the composite show substantially enhanced reaction kinetics compared with other Si NWs or Si particles. PMID:24522297

Ren, Jian-Guo; Wang, Chundong; Wu, Qi-Hui; Liu, Xiang; Yang, Yang; He, Lifang; Zhang, Wenjun

2014-03-21

447

Characterization of Free and Porous Silicon-Encapsulated Superparamagnetic Iron Oxide Nanoparticles as Platforms for the Development of Theranostic Vaccines  

PubMed Central

Tracking vaccine components from the site of injection to their destination in lymphatic tissue, and simultaneously monitoring immune effects, sheds light on the influence of vaccine components on particle and immune cell trafficking and therapeutic efficacy. In this study, we create a hybrid particle vaccine platform comprised of porous silicon (pSi) and superparamagnetic iron oxide nanoparticles (SPIONs). The impact of nanoparticle size and mode of presentation on magnetic resonance contrast enhancement are examined. SPION-enhanced relaxivity increased as the core diameter of the nanoparticle increased, while encapsulation of SPIONs within a pSi matrix had only minor effects on T2 and no significant effect on T2* relaxation. Following intravenous