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Sample records for gasb-based iii-v alloys

  1. III-V alloy heterostructure high speed avalanche photodiodes

    NASA Technical Reports Server (NTRS)

    Law, H. D.; Nakano, K.; Tomasetta, L. R.

    1979-01-01

    Heterostructure avalanche photodiodes have been successfully fabricated in several III-V alloy systems: GaAlAs/GaAs, GaAlSb/GaAlSb, and InGaAsP/InP. These diodes cover optical wavelengths from 0.4 to 1.8 micron. Early stages of development show very encouraging results. High speed response of less than 35 ps and high quantum efficiency more than 95 percent have been obtained. The dark currents and the excess avalanche noise are also dicussed. A direct comparison of GaAlSb, GaAlAsSb, and In GaAsP avalanche photodiodes is given.

  2. High bandgap III-V alloys for high efficiency optoelectronics

    DOEpatents

    Alberi, Kirstin; Mascarenhas, Angelo; Wanlass, Mark

    2017-01-10

    High bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a step-grade buffer between the substrate and at least one Al.sub.1-xIn.sub.xP layer. The buffer may begin with a layer that is substantially lattice matched to GaAs, and may then incrementally increase the lattice constant in each sequential layer until a predetermined lattice constant of Al.sub.1-xIn.sub.xP is reached.

  3. Method for preparing homogeneous single crystal ternary III-V alloys

    DOEpatents

    Ciszek, Theodore F.

    1991-01-01

    A method for producing homogeneous, single-crystal III-V ternary alloys of high crystal perfection using a floating crucible system in which the outer crucible holds a ternary alloy of the composition desired to be produced in the crystal and an inner floating crucible having a narrow, melt-passing channel in its bottom wall holds a small quantity of melt of a pseudo-binary liquidus composition that would freeze into the desired crystal composition. The alloy of the floating crucilbe is maintained at a predetermined lower temperature than the alloy of the outer crucible, and a single crystal of the desired homogeneous alloy is pulled out of the floating crucible melt, as melt from the outer crucible flows into a bottom channel of the floating crucible at a rate that corresponds to the rate of growth of the crystal.

  4. An extended Hückel study of the electronic properties of III-V compounds and their alloys

    NASA Astrophysics Data System (ADS)

    Ribeiro, Ingrid A.; Ribeiro, Fabio J.; Martins, A. S.

    2014-05-01

    In this work, we performed tight binding calculations of the electronic structure of III-V semiconductors compounds and their alloys based on the Extended Hückel Theory (EHT). In particular, this paper is focused on the dependency between band gap and the applied pressure and also the alloy composition.

  5. The role of strain in the surface structures of III-V alloyed semiconductor films

    NASA Astrophysics Data System (ADS)

    Bickel, Jessica E.

    As length scales continue to decrease, it is vital to understand the fundamental physical parameters governing surfaces and surface interactions. In semiconductors particularly, surface reconstructions are known to impact film growth, bulk atomic ordering and the development of interfacial structure, all of which can drastically impact device growth. While the parameters that determine surface reconstructions in homoepitaxially grown films are well known and understood, those that impact alloy film growth are less studied. This work examines the impact of strain on alloy surface reconstructions, using the III-V semiconductors as a model system for any covalently bonded crystal structure. The presence of surface reconstruction coexistence in both mixed cation and mixed anion systems suggests that localized strain fields on alloy surfaces stabilize elastic relaxation at boundaries, resulting in more complex surface structures than those seen on binary, unstrained films. Atomic size mismatch strain is shown to induce an ordering in alloyed surface reconstructions that is not seen in the non-alloyed constituent surfaces. Lattice mismatch strain is shown to both stabilize new reconstructions not common to the homoepitaxial system and to induce surface reconstruction coexistence on alloy surfaces. The supplied flux of material is shown to affect the kinetics of transformation between the two coexisting surface reconstructions and an incorporation model for material on the alloy surface is developed. The effects of strained surface reconstructions on subsequent film growth is explored and it is shown that identical films grown on two different surfaces have very different strain relaxation profiles, surface topographies and defect structures. The strain fields of surface reconstructions and defects are also shown to interact which may have an impact on the insertion of dislocations in these films. Combined together, this deep understanding of the role that alloy induced

  6. Epitaxial growth of III-V nitrides and phase separation and ordering in indium gallium nitride alloys

    NASA Astrophysics Data System (ADS)

    Doppalapudi, Dharanipal

    The family of III-V nitrides are wide band-gap semiconductors with a broad range of opto-electronic applications in LEDs, laser diodes, UV detectors as well as high temperature/high frequency devices. Due to the lack of good quality native substrates, GaN is grown on foreign substrates that have a lattice and thermal mismatch with GaN. This results in a material with a high density of defects, which in turn adversely affects the opto-electronic properties of the epilayer. In this study, GaN films were epitaxially grown on various substrates (C-plane sapphire, A-plane sapphire, SiC and ZnO) by molecular beam epitaxy. Additionally, GaN homoepitaxy onto laterally overgrown thick GaN substrates was investigated. It was demonstrated that the polarity of the GaN film plays a major role in determining the properties of the films. The growth parameters were optimized to eliminate inversion domain boundaries, which result in domains of opposite polarity in the GaN lattice. For growth on A-plane sapphire, it was found that substrate nitridation and low temperature buffer deposition are critical in order to obtain good epitaxial growth, in spite of the relatively small mismatch between the film and substrate. A crystallographic model was developed to explain this observation. By optimizing growth parameters, GaN films with excellent structural, transport, optical and device properties were grown. The second part of this research involves growth of ternary alloys and superlattice structures, which are essential in the fabrication of many devices. It was found that the InN-GaN pseudo-binary system is not homogeneous over the entire composition range. Due to the mismatch between the tetrahedral radii of GaN and InN, InGaN alloys exhibited phase separation and long-range atomic ordering. Investigations of InxGa1-xN films grown over a wide range of compositions by XRD and TEM showed that the predominant strain relieving mechanism was phase separation in films with x > 0.2, and

  7. Annealing group III-V compound doped silicon-germanium alloy for improved thermo-electric conversion efficiency

    NASA Technical Reports Server (NTRS)

    Vandersande, Jan W. (Inventor); Wood, Charles (Inventor); Draper, Susan L. (Inventor)

    1989-01-01

    The thermoelectric conversion efficiency of a GaP doped SiGe alloy is improved about 30 percent by annealing the alloy at a temperature above the melting point of the alloy, preferably stepwise from 1200 C to 1275 C in air to form large grains having a size over 50 microns and to form a GeGaP rich phase and a silicon rich phase containing SiP and SiO2 particles.

  8. Estimation of Bi induced changes in the direct E0 band gap of III-V-Bi alloys and comparison with experimental data

    NASA Astrophysics Data System (ADS)

    Samajdar, D. P.; Dhar, S.

    2016-03-01

    Quantum dielectric Theory (QDT) is used to explain the band gap bowing effect observed in III-V-Bismides such as InSb1-xBix, InAs1-xBix, InP1-xBix, GaSb1-xBix, GaAs1-xBix and GaP1-xBix. The dependence of the direct E0 band gap for these alloys on Bi mole fraction is calculated using QDT which requires the evaluation of the bowing parameter c. The bowing parameter gives the deviation of the direct E0 band gap from the linear relationship of E0 with Bi mole fraction. The band gap reduction values obtained using QDT are compared with those calculated using Virtual Crystal approximation (VCA) and Valence Band Anticrossing (VBAC) model as well as with the reported experimental data and the results of the comparison shows excellent agreement.

  9. Progress and Continuing Challenges in GaSb-based III-V Alloys and Heterostructures Grown by Organometallic Vapor Phase Epitaxy

    SciTech Connect

    CA Wang

    2004-05-06

    This paper discusses progress in the preparation of mid-IR GaSb-based III-V materials grown by organometallic vapor phase epitaxy (OMVPE). The growth of these materials is complex, and fundamental and practical issues associated with their growth are outlined. Approaches that have been explored to further improve the properties and performance are briefly reviewed. Recent materials and device results on GaInAsSb bulk layers and GaInAsSb/AlGaAsSb heterostructures, grown lattice matched to GaSb, are presented. State-of-the-art GaInAsSb materials and thermophotovoltaic devices have been achieved. This progress establishes the high potential of OMVPE for mid-IR GaSb-based devices.

  10. Study of the Local Structure of GALLIUM(X)INDIUM(1 -X)ARSENIDE(Y)ANTIMONY(1-Y), a Quaternary Iii-V Semiconductor Alloy, Using the Extended X-Ray Absorption Fine Structure (exafs) Technique.

    NASA Astrophysics Data System (ADS)

    Islam, Shaheen Momtaz

    The technological importance of quaternary semiconductor alloys has stimulated considerable interest in the basic physics of these materials. Understanding of the local structure of these alloys is of fundamental importance. In this work, the extended x-ray absorption fine structure (EXAFS) technique has been used to investigate the atomic-scale structure of the III-V quaternary alloy series Ga_{rm x}In _{rm 1-x}As _{rm y}Sb_ {rm 1-y}, where Ga and In atoms occupy one sublattice and As and Sb atoms are distributed over the other sublattice. Two series of these alloys were studied with varying x (from 0.05 to 0.95) and keeping y constant (y = 0.05 or y = 0.10). The samples were polycrystalline powders of various compositions. EXAFS data were obtained at the As K-edge at room temperature for all these alloys. Our measurements reveal the number and types of atoms and the nearest neighbor distances about the average As atom. Our results show a consistent deviation from random site occupation in all these alloys, with Ga-As (and therefore In-Sb) pairs being clearly preferred over In-As and Ga -Sb pairs. This result is consistent with a theoretical model based on the pair approximation. From EXAFS measurements we also observe that the variation of Ga-As and In-As near-neighbor distances with composition is linear and that the bond-lengths remain nearly constant, closer to those in the pure binary compounds and varying only by 0.03 to 0.05A. On the other hand, the x-ray diffraction results show that the average cation -anion distance in the alloys changes by as much as 0.165A in accordance with Vegard's law. This linear variation of lattice constant with composition between the end members suggests that the atomic volume is conserved regardless of the details of the local distortions of lattice.

  11. Discontinuities and bands alignments of strain-balanced III-V-N/III-V-Bi heterojunctions for mid-infrared photodetectors

    NASA Astrophysics Data System (ADS)

    Chakir, K.; Bilel, C.; Habchi, M. M.; Rebey, A.

    2017-02-01

    We have developed a 10- and 14-band anticrossing (BAC) models to investigate the band structures of dilute nitrides and dilute bismides alloys. In fact, the addition of Bi or N to III-V semiconductors causes a significant reduction in the band gap energy and an enhancement of the spin-orbit splitting energy. Further, the conduction and valence offsets between III-V-N/III-V-Bi were also investigated for different nitrogen and bismuth concentrations. For III-V-N/III-V-Bi heterojunctions, the strain-balanced criteria were undertaken by the zero stress analysis. The band alignment of strain-balanced GaAsN/GaAsBi, InPN/InPBi and InAsN/InAsBi is a type II. For InSbN/InSbBi heterostructure, the band lineup can be type I or II.

  12. Antimony Based III-V Thermophotovoltaic Devices

    SciTech Connect

    CA Wang

    2004-06-09

    Antimony-based III-V thermophotovoltaic (TPV) cells are attractive converters for systems with low radiator temperature around 1100 to 1700 K, since these cells potentially can be spectrally matched to the thermal source. Cells under development include GaSb and the lattice-matched GaInAsSb/GaSb and InPAsSb/InAs quaternary systems. GaSb cell technology is the most mature, owing in part to the relative ease in preparation of the binary alloy compared to quaternary GaInAsSb and InPAsSb alloys. Device performance of 0.7-eV GaSb cells exceeds 90% of the practical limit. GaInAsSb TPV cells have been the primary focus of recent research, and cells with energy gap E{sub g} ranging from {approx}0.6 to 0.49 eV have been demonstrated. Quantum efficiency and fill factor approach theoretical limits. Open-circuit voltage factor is as high as 87% of the practical limit for the higher-E{sub g} cells, but degrades to below 80% with decreasing E{sub g} of the alloy, which might be due to Auger recombination. InPAsSb cells are the least studied, and a cell with E{sub g} = 0.45-eV has extended spectral response out to 4.3 {micro}m. This paper briefly reviews the main contributions that have been made for antimonide-based TPV cells, and suggests additional studies for further performance enhancements.

  13. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, T.D.; Misra, M.

    1997-10-14

    A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector. 24 figs.

  14. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, Theodore D.; Misra, Mira

    1997-01-01

    A photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The photodetector includes a substrate with interdigitated electrodes formed on its surface. The substrate has a sapphire base layer, a buffer layer formed from a III-V nitride and a single crystal III-V nitride film. The three layers are formed by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-assisted MBE). Use of the ECR-assisted MBE process allows control and predetermination of the electrical properties of the photodetector.

  15. III-V arsenide-nitride semiconductor

    NASA Technical Reports Server (NTRS)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    2000-01-01

    III-V arsenide-nitride semiconductor are disclosed. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V materials varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V material can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  16. Hybrid III-V/silicon lasers

    NASA Astrophysics Data System (ADS)

    Kaspar, P.; Jany, C.; Le Liepvre, A.; Accard, A.; Lamponi, M.; Make, D.; Levaufre, G.; Girard, N.; Lelarge, F.; Shen, A.; Charbonnier, P.; Mallecot, F.; Duan, G.-H.; Gentner, J.-.; Fedeli, J.-M.; Olivier, S.; Descos, A.; Ben Bakir, B.; Messaoudene, S.; Bordel, D.; Malhouitre, S.; Kopp, C.; Menezo, S.

    2014-05-01

    The lack of potent integrated light emitters is one of the bottlenecks that have so far hindered the silicon photonics platform from revolutionizing the communication market. Photonic circuits with integrated light sources have the potential to address a wide range of applications from short-distance data communication to long-haul optical transmission. Notably, the integration of lasers would allow saving large assembly costs and reduce the footprint of optoelectronic products by combining photonic and microelectronic functionalities on a single chip. Since silicon and germanium-based sources are still in their infancy, hybrid approaches using III-V semiconductor materials are currently pursued by several research laboratories in academia as well as in industry. In this paper we review recent developments of hybrid III-V/silicon lasers and discuss the advantages and drawbacks of several integration schemes. The integration approach followed in our laboratory makes use of wafer-bonded III-V material on structured silicon-on-insulator substrates and is based on adiabatic mode transfers between silicon and III-V waveguides. We will highlight some of the most interesting results from devices such as wavelength-tunable lasers and AWG lasers. The good performance demonstrates that an efficient mode transfer can be achieved between III-V and silicon waveguides and encourages further research efforts in this direction.

  17. Lazarevicite-type short-range ordering in ternary III-V nanowires

    NASA Astrophysics Data System (ADS)

    Schnedler, M.; Lefebvre, I.; Xu, T.; Portz, V.; Patriarche, G.; Nys, J.-P.; Plissard, S. R.; Caroff, P.; Berthe, M.; Eisele, H.; Dunin-Borkowski, R. E.; Ebert, Ph.; Grandidier, B.

    2016-11-01

    Stabilizing ordering instead of randomness in alloy semiconductor materials is a powerful means to change their physical properties. We used scanning tunneling and transmission electron microscopies to reveal the existence of an unrecognized ordering in ternary III-V materials. The lazarevicite short-range order, found in the shell of InAs1 -xSbx nanowires, is driven by the strong Sb-Sb repulsion along <110 > atomic chains during their incorporation on unreconstructed {110 } sidewalls. Its spontaneous formation under group-III-rich conditions of growth offers the prospect to broaden the limited classes of ordered structures occurring in III-V semiconductor alloys.

  18. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, T.D.

    1998-12-08

    A bandpass photodetector using a III-V nitride and having predetermined electrical properties is disclosed. The bandpass photodetector detects electromagnetic radiation between a lower transition wavelength and an upper transition wavelength. That detector comprises two low pass photodetectors. The response of the two low pass photodetectors is subtracted to yield a response signal. 24 figs.

  19. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, Theodore D.

    1998-01-01

    A bandpass photodetector using a III-V nitride and having predetermined electrical properties. The bandpass photodetector detects electromagnetic radiation between a lower transition wavelength and an upper transition wavelength. That detector comprises two low pass photodetectors. The response of the two low pass photodetectors is subtracted to yield a response signal.

  20. Preparation of III-V semiconductor nanocrystals

    DOEpatents

    Alivisatos, A. Paul; Olshavsky, Michael A.

    1996-01-01

    Nanometer-scale crystals of III-V semiconductors are disclosed, They are prepared by reacting a group III metal source with a group V anion source in a liquid phase at elevated temperature in the presence of a crystallite growth terminator such as pyridine or quinoline.

  1. Preparation of III-V semiconductor nanocrystals

    DOEpatents

    Alivisatos, A.P.; Olshavsky, M.A.

    1996-04-09

    Nanometer-scale crystals of III-V semiconductors are disclosed. They are prepared by reacting a group III metal source with a group V anion source in a liquid phase at elevated temperature in the presence of a crystallite growth terminator such as pyridine or quinoline. 4 figs.

  2. Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

    DOEpatents

    Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

    2015-01-13

    Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

  3. Progress in III-V materials technology

    NASA Astrophysics Data System (ADS)

    Grant, Ian R.

    2004-12-01

    Compound semiconductors, in the form of GaAs and InP have achieved major commercial significance in areas of application such as mobile communications, displays and telecoms and offer a versatility of function beyond the capabilities of Si. III-V compounds, and in particular GaAs, have since their early development been the subject of defence related interest. Support from this sector established the basic materials technologies and nurtured development up until their commercial breakthrough into consumer products. GaAs, for example, now provides essential components for mobile phones and CD / DVD players. An overview is presented of the crystal growth and processing methods used in the manufacture of these materials. Current state of the art characteristics on crystal form and quality are discussed, together with the evolution of single crystal growth techniques. Consideration is given to how these principal compounds together with the minor materials, InSb, GaSb and InAs are employed in diverse applications over a broad spectral range, together with information on markets and future perspectives.

  4. III-V semiconductor devices integrated with silicon III-V semiconductor devices integrated with silicon

    NASA Astrophysics Data System (ADS)

    Hopkinson, Mark; Martin, Trevor; Smowton, Peter

    2013-09-01

    The integration of III-V semiconductor devices with silicon is one of the most topical challenges in current electronic materials research. The combination has the potential to exploit the unique optical and electronic functionality of III-V technology with the signal processing capabilities and advanced low-cost volume production techniques associated with silicon. Key industrial drivers include the use of high mobility III-V channel materials (InGaAs, InAs, InSb) to extend the performance of Si CMOS, the unification of electronics and photonics by combining photonic components (GaAs, InP) with a silicon platform for next-generation optical interconnects and the exploitation of large-area silicon substrates and high-volume Si processing capabilities to meet the challenges of low-cost production, a challenge which is particularly important for GaN-based devices in both power management and lighting applications. The diverse nature of the III-V and Si device approaches, materials technologies and the distinct differences between industrial Si and III-V processing have provided a major barrier to integration in the past. However, advances over the last decade in areas such as die transfer, wafer fusion and epitaxial growth have promoted widespread renewed interest. It is now timely to bring some of these topics together in a special issue covering a range of approaches and materials providing a snapshot of recent progress across the field. The issue opens a paper describing a strategy for the epitaxial integration of photonic devices where Kataria et al describe progress in the lateral overgrowth of InP/Si. As an alternative, Benjoucef and Reithmaier report on the potential of InAs quantum dots grown direct onto Si surfaces whilst Sandall et al describe the properties of similar InAs quantum dots as an optical modulator device. As an alternative to epitaxial integration approaches, Yokoyama et al describe a wafer bonding approach using a buried oxide concept, Corbett

  5. Resonant Raman Scattering Studies of Iii-V Semiconductor Microstructures

    NASA Astrophysics Data System (ADS)

    Delaney, Malcolm Emil

    1991-02-01

    Raman spectroscopy, an inelastic light scattering technique, explores III-V semiconductors by conveying crystal lattice structural information and by probing carrier dynamics both directly and via the electron-phonon interaction. We have examined three physical systems accentuating three aspects of Raman utility. Al_{rm x}Ga_{rm 1-x} As alloy work emphasizes electronic behavior, migration enhanced epitaxy (MEE) studies highlight structural results, and a phonon-assisted lasing project underscores electron -phonon interaction. The disorder-induced frequency difference between the dipole-forbidden and dipole-allowed longitudinal optic (LO) modes in Al_{rm x} Ga_{rm 1-x}As alloys has been investigated as a function of laser photon energy, aluminum mole fraction x, and the indirect versus direct nature of the electronic band gap. For the indirect gap alloy, the intermediate resonant state is an X-valley electron effectively localized because of its short inelastic lifetime. Raman scattering via this state is described by a calculation of the Raman susceptibility that considers the random alloy potential generated by local concentration fluctuations. MEE is a new growth technology that can order these materials in two spatial directions. In a GaSb/AlSb system we show Raman evidence of this ordering via observation of zone folded acoustic modes and compare to AlAs/GaAs results. In other work resonant Raman documents the effects on the dipole-forbidden interface mode of a periodic corrugation introduced in AlAs barrier GaAs single quantum wells. Finally, we investigate "phonon-assisted" lasing in photopumped quantum well heterostructure lasers. Resonant Raman is the natural choice to probe this system purported to have an enhanced electron-phonon interaction. For both the AlGaAs/GaAs and AlGaAs/GaAs/InGaAs structures examined, we provide evidence that indicates first order "phonon -assisted" lasing is actually renormalized band gap luminescence filtered by absorption from

  6. III-V High-Efficiency Multijunction Photovoltaics (Fact Sheet)

    SciTech Connect

    Not Available

    2011-06-01

    Capabilities fact sheet that includes scope, core competencies and capabilities, and contact/web information for III-V High-Efficiency Multijunction Photovoltaics at the National Center for Photovoltaics.

  7. Progress Towards III-V Photovoltaics on Flexible Substrates

    NASA Technical Reports Server (NTRS)

    McNatt, Jeremiah S.; Pal, AnnaMaria T.; Clark, Eric B.; Sayir, Ali; Raffaelle, Ryne P.; Bailey, Christopher G.; Hubbard, Seth M.; Maurer, William F.; Fritzemeier, Les

    2008-01-01

    Presented here is the recent progress of the NASA Glenn Research Center OMVPE group's efforts in the development of high efficiency thin-film polycrystalline III-V photovoltaics on optimum substrates. By using bulk polycrystalline germanium (Ge) films, devices of high efficiency and low mass will be developed and incorporated onto low-cost flexible substrates. Our progress towards the integration of high efficiency polycrystalline III-V devices and recrystallized Ge films on thin metal foils is discussed.

  8. Low dimensional III-V compound semiconductor structures

    NASA Astrophysics Data System (ADS)

    Kobayashi, Nobuhiko P.

    2009-08-01

    Material incompatibilities among dissimilar group III-V compound semiconductors (III-V CSs) often place limits on combining epitaxial thin films, however low-dimensional epitaxial structures (e.g., quantum dots and nanowires) demonstrate coherent growth even on incompatible surfaces. First, InAs QDs grown by molecular beam epitaxy on GaAs are described. Two-dimensional to three-dimensional morphological transition, lateral size evolution and vertical alignment of InAs QDs in a single and multiple stacks will be illustrated. Second, InP nanowires grown on non-single crystalline surfaces by metal organic chemical vapor deposition are described with the view toward applications where III-V CSs are functionally integrated onto various material platforms.

  9. Research progress of III-V laser bonding to Si

    NASA Astrophysics Data System (ADS)

    Bo, Ren; Yan, Hou; Yanan, Liang

    2016-12-01

    The vigorous development of silicon photonics makes a silicon-based light source essential for optoelectronics' integration. Bonding of III-V/Si hybrid laser has developed rapidly in the last ten years. In the tireless efforts of researchers, we are privileged to see these bonding methods, such as direct bonding, medium adhesive bonding and low temperature eutectic bonding. They have been developed and applied to the research and fabrication of III-V/Si hybrid lasers. Some research groups have made remarkable progress. Tanabe Katsuaki of Tokyo University successfully implemented a silicon-based InAs/GaAs quantum dot laser with direct bonding method in 2012. They have bonded the InAs/GaAs quantum dot laser to the silicon substrate and the silicon ridge waveguide, respectively. The threshold current of the device is as low as 200 A/cm2. Stevan Stanković and Sui Shaoshuai successfully produced a variety of hybrid III-V/Si laser with the method of BCB bonding, respectively. BCB has high light transmittance and it can provide high bonding strength. Researchers of Tokyo University and Peking University have realized III-V/Si hybrid lasers with metal bonding method. We describe the progress in the fabrication of III-V/Si hybrid lasers with bonding methods by various research groups in recent years. The advantages and disadvantages of these methods are presented. We also introduce the progress of the growth of III-V epitaxial layer on silicon substrate, which is also a promising method to realize silicon-based light source. I hope that readers can have a general understanding of this field from this article and we can attract more researchers to focus on the study in this field.

  10. III-V semiconductor solid solution single crystal growth

    NASA Technical Reports Server (NTRS)

    Gertner, E. R.

    1982-01-01

    The feasibility and desirability of space growth of bulk IR semiconductor crystals for use as substrates for epitaxial IR detector material were researched. A III-V ternary compound (GaInSb) and a II-VI binary compound were considered. Vapor epitaxy and quaternary epitaxy techniques were found to be sufficient to permit the use of ground based binary III-V crystals for all major device applications. Float zoning of CdTe was found to be a potentially successful approach to obtaining high quality substrate material, but further experiments were required.

  11. FOREWORD: The physics of III-V nitrides The physics of III-V nitrides

    NASA Astrophysics Data System (ADS)

    Ridley, B. K.

    2009-04-01

    The evolution of semiconductor physics is driven by the increasing sophistication of the art of crystal growing and fabrication techniques. From Ge at the birth of the transistor, possibly the purest material ever grown, through Si, the work-horse of the crystal revolution, to the III-Vs, whose optical properties opened up a second front, namely, optoelectronics. Crystal growth with monolayer control gave us quantum wells, superlattices, quantum wires and quantum dots, along with the quantum Hall effect and quantized resistance. The potential for high-power devices triggered interest in the III-V nitrides with their large bandgaps. The nitrides mostly crystallize in the hexagonal form, and this has introduced the phenomenon of spontaneous polarization into mainstream semiconductor physics. Its effect manifests itself in huge electric fields in heterostructures like AlGaN/GaN which, in turn, causes the induction of substantial electron populations in the channel of a HFET without the need for doping. High-power microwave transistors have been successfully fabricated, even though there are features associated with spontaneous polarization that still needs clarifying. Another strange effect is the large electron population on the surface of InN. The lack of a suitable substrate for growing GaN has meant that the dislocation density is higher than we would wish, but that situation is expected to steadily improve. Given the current interest in the physics of nitrides, it is natural to come across a special issue devoted to this topic. The difficulty presented by the surface layer in InN in the attempt to measure transport properties is discussed in the paper by King et al. A property that can affect transport is the lifetime of optical phonons and its dependence on electron density. Measurements of phonon lifetime in InN are reported by Tsen and Ferry, and in GaN channels, via the measure of hot-electron fluctuations, by Matulionis. The dependence on electron density is

  12. III-V aresenide-nitride semiconductor materials and devices

    NASA Technical Reports Server (NTRS)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    1997-01-01

    III-V arsenide-nitride semiconductor crystals, methods for producing such crystals and devices employing such crystals. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  13. Bulk crystal growth of antimonide based III-V compounds for thermophotovoltaics applications

    SciTech Connect

    Dutta, P.S.; Ostrogorsky, A.G.; Gutmann, R.J.

    1998-10-01

    In this paper, the bulk growth of crack-free GaInSb and single phase GaInAsSb alloys are presented. A new class of III-V quasi-binary [A{sub III}B{sub V}]{sub 12{minus}x}[C{sub III}D{sub V}]{sub x} semiconductor alloys has been synthesized and bulk crystals grown from the melt for the first time. The present investigation is focused on the quasi-binary alloy (GaSb){sub 1{minus}x}(InAs){sub x} (0 < x < 0.05) due to its importance for thermophotovoltaic applications. The structural properties of this melt-grown quasi-binary alloy are found to be significantly different from the conventional quaternary compound Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} with composition x = y. Synthesis and growth procedures are discussed. For the growth of ternary alloys, it was demonstrated that forced convection or mixing in the melt during directional solidification of In{sub x}Ga{sub 1{minus}x}Sb (0 < x < 0.1) significantly reduces cracks in the crystals.

  14. Influence of Bi-related impurity states on the bandgap and spin-orbit splitting energy of dilute III-V-Bi alloys: InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix

    NASA Astrophysics Data System (ADS)

    Samajdar, D. P.; Dhar, S.

    2016-01-01

    Valence Band Anticrossing (VBAC) Model is used to calculate the changes in band structure of Bi containing alloys such as InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix due to the incorporation of dilute concentrations of bismuth. The coupling parameter CBi which gives the magnitude of interaction of Bi impurity states with the LH, HH and SO sub bands in VBAC depends on the increase in the HH/LH related energy level EHH/LH+, location of the Bi related impurity level EBi and valence band offset ΔEVBM between the endpoint compounds in the corresponding III-V-Bi. The reduction in band gap as well as the enhancement of the spin-orbit splitting energy is well explained using this model and the calculated results are compared with the results of Virtual Crystal Approximation (VCA) and Density Functional Theory (DFT) calculations, as well as with the available experimental data and are found to have good agreement. The incorporation of Bi mainly perturbs the valence band due to the interaction of the Bi impurity states with the HH, LH and SO bands. The lowering of the conduction band minimum (CBM) due to VCA is added with the upward movement of the HH/LH bands to get the total reduction in band gap for the bismides. The valence band shifts of 31.9, 32.5, 20.8 and 12.4 meV/at%Bi for InP1-xBix, InAs1-xBix, InSb1-xBix and GaSb1-xBix respectively constitute 65, 76, 59 and 31% of the total band gap reduction and the rest is the contribution of the conduction band shift. The spin-orbit splitting energy also shows significant increase with the maximum change in InPBi and the minimum in InSbBi. The same is true for Ga containing bismides if we make a comparison with the available values for GaAsBi and GaPBi with that of GaSbBi. It has also been observed that the increase in splitting energy is greater in case of the bismides such as InAsBi, InPBi and GaAsBi than the bismides such as InSbBi and GaSbBi with the parent substrates having higher values of splitting energy. This may

  15. Subnanometer scale characterization of III-V-heterostructures

    SciTech Connect

    Lakner, H.

    1996-12-31

    Heterostructures based on III-V semiconductors play a dominant role for the production of optoelectronic /1/ and electronic high-speed or high-frequency /2/ devices. The necessary band-gap engineering is achieved by optimized growth procedures which allow to change the chemical composition and the crystal structure (e.g., strain or ordering) on the subnanometer scale. The evaluation of individual heterointerfaces with respect to chemical composition and crystal structure requires characterization techniques which offer the necessary high spatial resolution. Scanning transmission electron microscopy (STEM) offers several of such quantitative techniques. It is the intention of this paper to demonstrate the capabilities of STEM in the subnanometer characterization of III-V-heterostructures based on InP-substrates. Additionally, the data obtained from nanocharacterization can be correlated to device performance.

  16. Silicon surface preparation for III-V molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Madiomanana, K.; Bahri, M.; Rodriguez, J. B.; Largeau, L.; Cerutti, L.; Mauguin, O.; Castellano, A.; Patriarche, G.; Tournié, E.

    2015-03-01

    We report on a silicon substrate preparation for III-V molecular-beam epitaxy (MBE). It combines sequences of ex situ and in situ treatments. The ex situ process is composed of cycles of HF dip and O2 plasma treatments. Ellipsometry and atomic force microscopy performed after each step during the substrate preparation reveal surface cleaning and de-oxidation. The in situ treatment consists in flash annealing the substrate in the MBE chamber prior to epitaxial growth. GaSb-based multiple quantum well heterostructures emitting at 1.55 μm were grown by MBE on Si substrates prepared by different methods. Structural characterizations using XRD and TEM coupled with photoluminescence spectroscopy demonstrates the efficiency of our preparation process. This study thus unravels a simple and reproducible protocol to prepare the Si surface prior to III-V MBE.

  17. Investigation of new semiinsulating behavior of III-V compounds

    NASA Technical Reports Server (NTRS)

    Lagowski, Jacek

    1990-01-01

    The investigation of defect interactions and properties related to semiinsulating behavior of III-V semiconductors resulted in about twenty original publications, six doctoral thesis, one masters thesis and numerous conference presentations. The studies of new compensation mechanisms involving transition metal impurities have defined direct effects associated with deep donor/acceptor levels acting as compensating centers. Electrical and optical properties of vanadium and titanium levels were determined in GaAs, InP and also in ternary compounds InGaAs. The experimental data provided basis for the verification of chemical trends and the VRBE method. They also defined compositional range for III-V mixed crystals whereby semiinsulating behavior can be achieved using transition elements deep levels and a suitable codoping with shallow donor/acceptor impurities.

  18. Super-High Iii-V Tandem and Multijunction Cells

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Masafumi

    2015-10-01

    The following sections are included: * Introduction * Principles of super-high-efficiency multijunction solar cells * Epitaxial technologies for growing III-V compound cells * Monolithic vs. multi-terminal connection modes * Key issues for realising high-efficiency multijunction solar cells * High-efficiency InGaP/GaAs/Ge three-junction solar cells and their space applications * Multijunction solar cells: recent results * Future directions * Acknowledgements * References

  19. Method of fabricating vertically aligned group III-V nanowires

    DOEpatents

    Wang, George T; Li, Qiming

    2014-11-25

    A top-down method of fabricating vertically aligned Group III-V micro- and nanowires uses a two-step etch process that adds a selective anisotropic wet etch after an initial plasma etch to remove the dry etch damage while enabling micro/nanowires with straight and smooth faceted sidewalls and controllable diameters independent of pitch. The method enables the fabrication of nanowire lasers, LEDs, and solar cells.

  20. Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport

    SciTech Connect

    Tanaka, Masaaki; Ohya, Shinobu Nam Hai, Pham

    2014-03-15

    Spin-based electronics or spintronics is an emerging field, in which we try to utilize spin degrees of freedom as well as charge transport in materials and devices. While metal-based spin-devices, such as magnetic-field sensors and magnetoresistive random access memory using giant magnetoresistance and tunneling magnetoresistance, are already put to practical use, semiconductor-based spintronics has greater potential for expansion because of good compatibility with existing semiconductor technology. Many semiconductor-based spintronics devices with useful functionalities have been proposed and explored so far. To realize those devices and functionalities, we definitely need appropriate materials which have both the properties of semiconductors and ferromagnets. Ferromagnetic semiconductors (FMSs), which are alloy semiconductors containing magnetic atoms such as Mn and Fe, are one of the most promising classes of materials for this purpose and thus have been intensively studied for the past two decades. Here, we review the recent progress in the studies of the most prototypical III-V based FMS, p-type (GaMn)As and its heterostructures with focus on tunneling transport, Fermi level, and bandstructure. Furthermore, we cover the properties of a new n-type FMS, (In,Fe)As, which shows electron-induced ferromagnetism. These FMS materials having zinc-blende crystal structure show excellent compatibility with well-developed III-V heterostructures and devices.

  1. Physics, fabrication and characterization of III-V multi-gate FETs for low power electronics

    NASA Astrophysics Data System (ADS)

    Thathachary, Arun V.

    With transistor technology close to its limits for power constrained scaling and the simultaneous emergence of mobile devices as the dominant driver for new scaling, a pathway to significant reduction in transistor operating voltage to 0.5V or lower is urgently sought. This however implies a fundamental paradigm shift away from mature Silicon technology. III-V compound semiconductors hold great promise in this regard due to their vastly superior electron transport properties making them prime candidates to replace Silicon in the n-channel transistor. Among the plethora of binary and ternary compounds available in the III-V space, InxGa1-xAs alloys have attracted significant interest due to their excellent electron mobility, ideally placed bandgap and mature growth technology. Simultaneously, electrostatic control mandates multigate transistor designs such as the FinFET at extremely scaled nodes. This dissertation describes the experimental realization of III-V FinFETs incorporating InXGa1-XAs heterostructure channels for high performance, low power logic applications. The chapters that follow present experimental demonstrations, simulations and analysis on the following aspects (a) motivation and key figures of merit driving material selection and design; (b) dielectric integration schemes for high-k metal-gate stack (HKMG) realization on InXGa 1-XAs, including surface clean and passivation techniques developed for high quality interfaces; (c) novel techniques for transport (mobility) characterization in nanoscale multi-gate FET architectures with experimental demonstration on In0.7Ga0.3As nanowires; (d) Indium composition and quantum confined channel design for InXGa 1-XAs FinFETs and (e) InAs heterostructure designs for high performance FinFETs. Each chapter also contains detailed benchmarking of results against state of the art demonstrations in Silicon and III-V material systems. The dissertation concludes by assessing the feasibility of InXGa 1-XAs Fin

  2. Low-Cost Growth of III-V Layers on Si Using Close-Spaced Vapor Transport

    SciTech Connect

    Boucher, Jason W.; Greenaway, Ann L.; Ritenour, Andrew J.; Davis, Allison L.; Bachman, Benjamin F.; Aloni, Shaul; Boettcher, Shannon W.

    2015-06-14

    Close-spaced vapor transport (CSVT) uses solid precursors to deposit material at high rates and with high precursor utilization. The use of solid precursors could significantly reduce the costs associated with III-V photovoltaics, particularly if growth on Si substrates can be demonstrated. We present preliminary results of the growth of GaAs1-xPx with x ≈ 0.3 and 0.6, showing that CSVT can be used to produce III-V-V’ alloys with band gaps suitable for tandem devices. Additionally, we have grown GaAs on Si by first thermally depositing films of Ge and subsequently depositing GaAs by CSVT. Patterning the Ge into islands prevents cracking due to thermal mismatch and is useful for potential tandem structures.

  3. Effective electron mass in quantum wires of III-V, ternary and quaternary materials.

    PubMed

    Paitya, N; Ghatak, K P

    2012-12-01

    In this paper, an attempt is made to study the effective electron mass (EEM) in Quantum wires (QWs) of III-V, ternary and quaternary materials on the basis of three and two band models of Kane within the framework of k x p formalism. It has been found, taking QWs of InAs, InSb, GaAs, Hg(1-x)Cd(x)Te and In(1-x)Ga(x)As(1-y)P(t) that the 1D EEM increases with electron concentration per unit length and decreases with increasing film thickness respectively. For ternary and quaternary materials the EEM increases with increase in alloy composition. Under certain special conditions all the results for all the 1-D materials get simplified into the well known parabolic energy bands and thus confirming the compatibility test. The results of this paper find two applications in the fields of nanoscience and technology.

  4. Final Report: Vapor Transport Deposition for Thin Film III-V Photovoltaics

    SciTech Connect

    Boettcher, Shannon; Greenaway, Ann; Boucher, Jason; Aloni, Shaul

    2016-02-10

    ternary GaAsxP1-x and In0.5Ga0.5P alloys, with composition set by the ratio of GaAs/GaP or InP/GaP mixed as the source powder. GaAs0.3P0.7 has the appropriate bandgap to serve as a top cell on Si and In0.5Ga0.5P is near the composition used as a surface passivation layer on GaAs pn junction photovoltaics. In the final task we demonstrated III-V selective area epitaxy using CSVT as a first step toward the growth of III-V micro- or nanostructures for an integrated tandem solar cell on Si. We also found that direct epitaxial growth on Si appears to be impossible in the current H2O-CSVT reactor design, likely due to the formation of SiOx. This work sets the stage for targeted development of an improved CSVT process and for the scale up of the proof-of-concept work from a research to manufacturing-relevant platform. Replacing H2O as a transport agent with HCl would provide the ability to deposit directly on Si by avoiding oxide formation and to allow for the deposition of Al-containing alloys that would otherwise oxidize. Improved engineering design and implementation of an in-line multi-station CSVT would allow for direct deposition of device structures in a single system.

  5. Exploring Cryogenic Focused Ion Beam Milling as a Group III-V Device Fabrication Tool

    DTIC Science & Technology

    2013-09-01

    focused ion beam (cryo-FIB) milling as a Group III-V device fabrication tool. Cryogenic cooling of III-V semiconductor material during Ga + FIB irradiation...potential applications of cryogenic focused ion beam (cryo-FIB) milling as a Group III-V device fabrication tool. Cryogenic cooling of III-V semiconductor...sensitivity to the Ga ion beam . This sensitivity is manifested as changes in the structure and chemical composition of the starting material upon exposure to

  6. Hybrid III-V/silicon SOA for photonic integrated circuits

    NASA Astrophysics Data System (ADS)

    Kaspar, P.; Brenot, R.; Le Liepvre, A.; Accard, A.; Make, D.; Levaufre, G.; Girard, N.; Lelarge, F.; Duan, G.-H.; Olivier, S.; Jany, Christophe; Kopp, C.; Menezo, S.

    2014-11-01

    Silicon photonics has reached a considerable level of maturity, and the complexity of photonic integrated circuits (PIC) is steadily increasing. As the number of components in a PIC grows, loss management becomes more and more important. Integrated semiconductor optical amplifiers (SOA) will be crucial components in future photonic systems for loss compensation. In addition, there are specific applications, where SOAs can play a key role beyond mere loss compensation, such as modulated reflective SOAs in carrier distributed passive optical networks or optical gates in packet switching. It is, therefore, highly desirable to find a generic integration platform that includes the possibility of integrating SOAs on silicon. Various methods are currently being developed to integrate light emitters on silicon-on-insulator (SOI) waveguide circuits. Many of them use III-V materials for the hybrid integration on SOI. Various types of lasers have been demonstrated by several groups around the globe. In some of the integration approaches, SOAs can be implemented using essentially the same technology as for lasers. In this paper we will focus on SOA devices based on a hybrid integration approach where III-V material is bonded on SOI and a vertical optical mode transfer is used to couple light between SOI waveguides and guides formed in bonded III-V semiconductor layers. In contrast to evanescent coupling schemes, this mode transfer allows for a higher confinement factor in the gain material and thus for efficient light amplification over short propagation distances. We will outline the fabrication process of our hybrid components and present some of the most interesting results from a fabricated and packaged hybrid SOA.

  7. DX centers in III-V semiconductors under hydrostatic pressure

    SciTech Connect

    Wolk, J.A.

    1992-11-01

    DX centers are deep level defects found in some III-V semiconductors. They have persistent photoconductivity and large difference between thermal and optical ionization energies. Hydrostatic pressure was used to study microstructure of these defects. A new local vibrational mode (LVM) was observed in hydrostatically stressed, Si-doped GaAs. Corresponding infrared absorption peak is distinct from the Si{sub Ga} shallow donor LVM peak, which is the only other LVM peak observed in our samples, and is assigned to the Si DX center. Analysis of the relative intensities of the Si DX LVM and the Si shallow donor LVM peaks, combined with Hall effect and resistivity indicate that the Si DX center is negatively charged. Frequency of this new mode provides clues to the structure of this defect. A pressure induced deep donor level in S-doped InP was also discovered which has the properties of a DX center. Pressure at which the new defect becomes more stable than the shallow donor is 82 kbar. Optical ionization energy and energy dependence of the optical absorption cross section was measured for this new effect. Capture barrier from the conduction band into the DX state were also determined. That DX centers can be formed in InP by pressure suggests that DX states should be common in n-type III-V semiconductors. A method is suggested for predicting under what conditions these defects will be the most stable form of the donor impurity.

  8. Spin-Seebeck Effect in III-V Based Semiconductors

    NASA Astrophysics Data System (ADS)

    Jaworski, Christopher M.; Myers, Roberto C.; Heremans, Joseph P.

    2012-02-01

    The spin-Seebeck effect has now been observed in metals^1 (NiFe), semiconductors^2 (GaMnAs), and insulators^3 (YIG). It consists of a thermally generated spin distribution that is phonon driven. Here we extend our measurements of the spin-Seebeck effect to other group III-V based magnetic semiconductors and present measurements of conventional thermomagnetic and galvanomagnetic properties as well as the spin-Seebeck effect. Work supported by the National Science Foundation, NSF-CBET-1133589 1. K. Uchida, et al., Nature 455 778 (2008) 2. C.M. Jaworski et al., Nature Materials 8 898 (2010), Phys. Rev. Lett. 106 186601 (2011) 3. K. Uchida, et al., Nature Materials 8 893 (2010)

  9. III-V Nanowire Array Growth by Selective Area Epitaxy

    SciTech Connect

    Chu, Hyung-Joon; Stewart, Lawrence; Yeh, Tingwei; Dapkus, P. Daniel

    2011-12-23

    III-V semiconductor nanowires are unique material phase due to their high aspect ratio, large surface area, and strong quantum confinement. This affords the opportunity to control charge transport and optical properties for electrical and photonic applications. Nanoscale selective area metalorganic chemical vapor deposition growth (NS-SAG) is a promising technique to maximize control of nanowire diameter and position, which are essential for device application. In this work, InP and GaAs nanowire arrays are grown by NS-SAG. We observe enhanced sidewall growth and array uniformity disorder in high growth rate condition. Disorder in surface morphology and array uniformity of InP nanowire array is explained by enhanced growth on the sidewall and stacking faults. We also find that AsH{sub 3} decomposition on the sidewall affects the growth behavior of GaAs nanowire arrays.

  10. III-V nitride semiconductors for solar hydrogen production

    NASA Astrophysics Data System (ADS)

    Parameshwaran, Vijay; Gallinat, Chad; Enck, Ryan W.; Sampath, Anand V.; Shen, Paul H.; Kuykendall, Tevye; Aloni, Shaul; Wraback, Michael; Clemens, Bruce M.

    2012-06-01

    Photoelectrochemical cells are devices that can convert solar radiation to hydrogen gas through a water decomposition process. In this process, energy is converted from incident photons to the bonds of the generated H2 molecules. The solar radiation absorption, electron-hole pair splitting, and photoelectrolysis half reactions all occur in the vicinity of the electrode-electrolyte interface. As a result, engineering the electrode material and its interaction with the electrolyte is important in investigating and improving the energy conversion process in these devices. III-V nitride materials are promising candidates for photoelectrochemical energy applications. We demonstrate solar-to-hydrogen conversion in these cells using p-type GaN and n-type InGaN as a photocathode and photoanode material, respectively. Additionally, we demonstrate heteroepitaxial MOCVD growth of GaP on Si, enabling future work in developing GaPN as a photocathode material.

  11. III-V-on-silicon multi-frequency lasers.

    PubMed

    Keyvaninia, S; Verstuyft, S; Pathak, S; Lelarge, F; Duan, G-H; Bordel, D; Fedeli, J-M; De Vries, T; Smalbrugge, B; Geluk, E J; Bolk, J; Smit, M; Roelkens, G; Van Thourhout, D

    2013-06-03

    Compact multi-frequency lasers are realized by combining III-V based optical amplifiers with silicon waveguide optical demultiplexers using a heterogeneous integration process based on adhesive wafer bonding. Both devices using arrayed waveguide grating routers as well as devices using ring resonators as the demultiplexer showed lasing with threshold currents between 30 and 40 mA and output powers in the order of a few mW. Laser operation up to 60°C is demonstrated. The small bending radius allowable for the silicon waveguides results in a short cavity length, ensuring stable lasing in a single longitudinal mode, even with relaxed values for the intra-cavity filter bandwidths.

  12. Ballistic transport and luminescence in III-V semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Yi, Wei

    This thesis describes research to develop novel scanning probe methods employing ballistic electron emission to characterize nanoscale carrier transport and luminescence of quantum-confined III-V semiconductor nanostructures. First, spectroscopic and microscopic ballistic electron emission luminescence (BEEL) of an InAs quantum dot heterostructure based on three-terminal hot electron injection using a scanning tunneling microscope and a planar tunnel-junction transistor is described in detail. Second, BEEL device simulation based on one-dimensional Poisson equation and carrier drift-diffusion model is examined. Third, a scheme to integrate a photon detector directly into a BEEL heterostructure to improve the photon collection efficiency is presented. Fourth, experimental results toward development of a dual scanning probe microscopy to study nanoscale metal-semiconductor interfaces without the requirement of an externally-contacted continuous metal thin film are described. Finally, some prospects of ballistic carrier spintronic devices are discussed.

  13. Nonclassical devices in SOI: Genuine or copyright from III V

    NASA Astrophysics Data System (ADS)

    Luryi, S.; Zaslavsky, A.

    2007-02-01

    The combination of semiconductor-on-insulator (SOI) substrates with ultrathin Si (or Ge) channel and gate insulator layers opens new opportunities for nonclassical CMOS-compatible devices and possibly optical sources. Unlike their III-V counterparts, which often came first, SOI-based devices have the crucial advantage of potential integrability with dominant silicon technology. We discuss the examples of lateral and vertical tunneling transistors, as well as a tunneling-based SOI intersubband laser. None of these devices has progressed beyond either proof-of-concept demonstrations or, in the case of the intersubband laser, a purely theoretical concept. Still, the unique characteristics deriving from quantum mechanical tunneling make such devices an interesting playground for innovative device research, especially as standard Si CMOS heads towards the rapidly approaching end of scaling.

  14. Characteristics of III-V Semiconductor Devices at High Temperature

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Young, Paul G.; Taub, Susan R.; Alterovitz, Samuel A.

    1994-01-01

    This paper presents the development of III-V based pseudomorphic high electron mobility transistors (PHEMT's) designed to operate over the temperature range 77 to 473 K (-196 to 200 C). These devices have a pseudomorphic undoped InGaAs channel that is sandwiched between an AlGaAs spacer and a buffer layer; gate widths of 200, 400, 1600, and 3200 micrometers; and a gate length of 2 micrometers. Measurements were performed at both room temperature and 473 K (200 C) and show that the drain current decreases by 30 percent and the gate current increases to about 9 microns A (at a reverse bias of -1.5 V) at the higher temperature. These devices have a maximum DC power dissipation of about 4.5 W and a breakdown voltage of about 16 V.

  15. Carbon doping of III-V compound semiconductors

    SciTech Connect

    Moll, Amy Jo

    1994-09-01

    Focus of the study is C acceptor doping of GaAs, since C diffusion coefficient is at least one order of magnitude lower than that of other common p-type dopants in GaAs. C ion implantation results in a concentration of free holes in the valence band < 10% of that of the implanted C atoms for doses > 1014/cm2. Rutherford backscattering, electrical measurements, Raman spectroscopy, and Fourier transform infrared spectroscopy were amonth the techniques used. Ga co-implantation increased the C activation in two steps: first, the additional radiation damage creates vacant As sites that the implanted C can occupy, and second, it maintains the stoichiometry of the implanted layer, reducing the number of compensating native defects. In InP, the behavior of C was different from that in GaAs. C acts as n-type dopant in the In site; however, its incorporation by implantation was difficult to control; experiments using P co-implants were inconsistent. The lattice position of inactive C in GaAs in implanted and epitaxial layers is discussed; evidence for formation of C precipitates in GaAs and InP was found. Correlation of the results with literature on C doping in III-V semiconductors led to a phenomenological description of C in III-V compounds (particularly GaAs): The behavior of C is controlled by the chemical nature of C and the instrinsic Fermi level stabilization energy of the material.

  16. III-V Compound Detectors for CO2 DIAL Measurements

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Abedin, M. Nurul; Sulima, Oleg V.; Ismail, Syed; Singh, Upendra N.

    2005-01-01

    Profiling of atmospheric carbon dioxide (CO2) is important for understanding the natural carbon cycle on Earth and its influence on global warming and climate change. Differential absorption lidar is a powerful remote sensing technique used for profiling and monitoring atmospheric constituents. Recently there has been an interest to apply this technique, at the 2 m wavelength, for investigating atmospheric CO2. This drives the need for high quality detectors at this wavelength. Although 2 m detectors are commercially available, the quest for a better detector is still on. The detector performance, regarding quantum efficiency, gain and associated noise, affects the DIAL signal-to-noise ratio and background signal, thereby influencing the instrument sensitivity and dynamic range. Detectors based on the III-V based compound materials shows a strong potential for such application. In this paper the detector requirements for a long range CO2 DIAL profiles will be discussed. These requirements were compared to newly developed III-V compound infrared detectors. The performance of ternary InGaSb pn junction devices will be presented using different substrates, as well as quaternary InGaAsSb npn structure. The performance study was based on experimental characterization of the devices dark current, spectral response, gain and noise. The final results are compared to the current state-of-the-art InGaAs technology. Npn phototransistor structure showed the best performance, regarding the internal gain and therefore the device signal-to-noise ratio. 2-micrometers detectivity as high as 3.9 x 10(exp 11) cmHz(sup 1/2)/W was obtained at a temperature of -20 C and 4 V bias voltage. This corresponds to a responsivity of 2650 A/W with about 60% quantum efficiency.

  17. Methods for fabricating thin film III-V compound solar cell

    DOEpatents

    Pan, Noren; Hillier, Glen; Vu, Duy Phach; Tatavarti, Rao; Youtsey, Christopher; McCallum, David; Martin, Genevieve

    2011-08-09

    The present invention utilizes epitaxial lift-off in which a sacrificial layer is included in the epitaxial growth between the substrate and a thin film III-V compound solar cell. To provide support for the thin film III-V compound solar cell in absence of the substrate, a backing layer is applied to a surface of the thin film III-V compound solar cell before it is separated from the substrate. To separate the thin film III-V compound solar cell from the substrate, the sacrificial layer is removed as part of the epitaxial lift-off. Once the substrate is separated from the thin film III-V compound solar cell, the substrate may then be reused in the formation of another thin film III-V compound solar cell.

  18. Spectroscopic characterization of III-V semiconductor nanomaterials

    NASA Astrophysics Data System (ADS)

    Crankshaw, Shanna Marie

    III-V semiconductor materials form a broad basis for optoelectronic applications, including the broad basis of the telecom industry as well as smaller markets for high-mobility transistors. In a somewhat analogous manner as the traditional silicon logic industry has so heavily depended upon process manufacturing development, optoelectronics often relies instead on materials innovations. This thesis focuses particularly on III-V semiconductor nanomaterials, detailed characterization of which is invaluable for translating the exhibited behavior into useful applications. Specifically, the original research described in these thesis chapters is an investigation of semiconductors at a fundamental materials level, because the nanostructures in which they appear crystallize in quite atypical forms for the given semiconductors. Rather than restricting the experimental approaches to any one particular technique, many different types of optical spectroscopies are developed and applied where relevant to elucidate the connection between the crystalline structure and exhibited properties. In the first chapters, for example, a wurtzite crystalline form of the prototypical zincblende III-V binary semiconductor, GaAs, is explored through polarization-dependent Raman spectroscopy and temperature-dependent photoluminescence, as well as second-harmonic generation (SHG). The altered symmetry properties of the wurtzite crystalline structure are particularly evident in the Raman and SHG polarization dependences, all within a bulk material realm. A rather different but deeply elegant aspect of crystalline symmetry in GaAs is explored in a separate study on zincblende GaAs samples quantum-confined in one direction, i.e. quantum well structures, whose quantization direction corresponds to the (110) direction. The (110) orientation modifies the low-temperature electron spin relaxation mechanisms available compared to the usual (001) samples, leading to altered spin coherence times explored

  19. Integration of III-V materials and Si-CMOS through double layer transfer process

    NASA Astrophysics Data System (ADS)

    Lee, Kwang Hong; Bao, Shuyu; Fitzgerald, Eugene; Tan, Chuan Seng

    2015-03-01

    A method to integrate III-V compound semiconductor and SOI-CMOS on a common Si substrate is demonstrated. The SOI-CMOS layer is temporarily bonded on a Si handle wafer. Another III-V/Si substrate is then bonded to the SOI-CMOS containing handle wafer. Finally, the handle wafer is released to realize the SOI-CMOS on III-V/Si hybrid structure on a common substrate. Through this method, high temperature III-V materials growth can be completed without the presence of the temperature sensitive CMOS layer, hence damage to the CMOS layer is avoided.

  20. Surface Leakage Mechanisms in III-V Infrared Barrier Detectors

    NASA Astrophysics Data System (ADS)

    Sidor, D. E.; Savich, G. R.; Wicks, G. W.

    2016-09-01

    Infrared detector epitaxial structures employing unipolar barriers exhibit greatly reduced dark currents compared to simple pn-based structures. When correctly positioned within the structure, unipolar barriers are highly effective at blocking bulk dark current mechanisms. Unipolar barriers are also effective at suppressing surface leakage current in infrared detector structures employing absorbing layers that possess the same conductivity type in their bulk and at their surface. When an absorbing layer possesses opposite conductivity types in its bulk and at its surface, unipolar barriers are not solutions to surface leakage. This work reviews empirically determined surface band alignments of III-V semiconductor compounds and modeled surface band alignments of both gallium-free and gallium-containing type-II strained layer superlattice material systems. Surface band alignments are used to predict surface conductivity types in several detector structures, and the relationship between surface and bulk conductivity types in the absorbing layers of these structures is used as the basis for explaining observed surface leakage characteristics.

  1. Chemical vapour transport of III-V semiconductor materials

    NASA Astrophysics Data System (ADS)

    Davis, Mervyn Howard

    Over the temperature range 770 to 1310 K, however, two bromides compete for prominence, dependent upon temperature. In both instances, it is shown that vapour transport becomes rate limited at low temperature. Further to the chemical vapour transport of indium phosphide, the dissociative sublimation of the compound has also been investigated. Raman spectroscopy has been used to identify high temperature molecular species involved in vapour transport of III-V semiconductor materials. Supplementary work has been performed on the thermochemistry of indium monobromide. The heat of formation of indium bromide crystals has been determined using a solution calormetric technique. Differential scanning calorimetry was used to measure the heat capacity and heat of fusion, of the salt. An entrainment study of the evaporation of liquid indium monobromide was undertaken to yield a value for its heat of vaporisation. Using a statistical thermodynamic approach, the heat capacity of the vapour was calculated. Collating the information, a value for the heat of formation of indium monobromide gas at 1000 K has been calculated for use in other thermodynamic calculations.

  2. In situ characterisation of epiready III V substrates for MOVPE

    NASA Astrophysics Data System (ADS)

    Allwood, D. A.; Grant, I. R.; Mason, N. J.; Palmer, R. A.; Walker, P. J.

    2000-12-01

    The use of the term epiready in relation to III-V substrates in MOVPE is ill defined and poorly understood. In this paper we attempt to clarify some of the issues associated with the term epiready, in particular, the thickness and distribution of native oxide on the surface of a GaAs wafer. The surface quality of a wafer is established at three stages, fresh from the packet, oxide removed, and after growth. The surface is assessed by means of atomic force microscopy on a microscopic level and laser light scattering and oxide thickness mapping on a macroscopic scale. GaAs substrates from long-term storage are also examined. It is shown that even long-term stored wafers (in excess of six years) with quite thick native oxide layers can be successfully deoxidised to give atomically flat terraces and can subsequently be used for successful homoepitaxial growth provided that atomic hydrogen (in this case, from the arsenic precursor) is used in the deoxidation stage. No difference between various manufacturers substrates has been found in respect to storage and subsequent use, nor has any difference been established between doped and undoped wafers.

  3. Fullerene Molecules and Other Clusters of III-V Compounds

    NASA Astrophysics Data System (ADS)

    Hira, Ajit; Auxier, John, II; Lucero, Melinda

    2010-03-01

    The goal of the our work is to derive geometries of fullerene-like cages and other clusters of atoms from groups III and V of the periodic table. Our previous research focused on Carbon Fullerenes and on GanAsn clusters (n = 1 thru 12). Our research group has made an original discovery about GanAsn clusters. In our work on nanotechnology to date, we used the hybrid ab initio methods of quantum chemistry to derive the different geometries for the clusters of interest. We also calculated binding energies, bond-lengths, ionization potentials, electron affinities and HOMO-LUMO gaps, and IR spectra for these geometries. Of particular significance was the magic number for GaAs cluster stability that we found at n = 8. This is important because materials containing controlled III-V nanostructures provide the capability of preparing new classes of materials with enhanced optical, magnetic, chemical sensor and photo-catalytic properties. The second phase of the investigation will examine the effects of confinement on the optical properties the clusters. It will be interesting to observe novel linear as well as nonlinear optical processes in them. The third phase of the investigation will focus on the improved design of solar cells based on the optical properties of the clusters.

  4. Fabrication and characterization of nanostructured III-V thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Novotny, Clint; Sharifi, Fred

    2013-09-01

    Approximately two thirds of all fossil fuel used is lost as heat. Thermoelectric materials, which convert heat into electrical energy, may provide a solution to partially recover some of this lost energy. To date, most commercial thermoelectric materials are too inefficient to be a viable option for most waste heat applications. This research proposes to investigate the fabrication and characterization of nanostructured III-V semiconductor thermoelectric materials with the goal of increasing the performance of existing technology. In order to improve thermoelectric material efficiency, either the lattice thermal conductivity must be lowered or the thermoelectric power factor must be increased. This research will focus on the latter by modifying the density of states of the semiconductor material and studying the effect of quantum confinement on the material's thermoelectric properties. Using focused ion beam milling, nanostructured cantilevers are fabricated from single crystal wafers. An all around gate dielectric and electrode are deposited to create a depletion region along the outer core of the cantilever, thus creating an inner conductive core. The Seebeck coefficient can then be measured as a function of confinement by varying the gate voltage. This technique can be applied to various material systems to investigate the effects of confinement on their thermoelectric properties.

  5. Antisites in III-V semiconductors: Density functional theory calculations

    SciTech Connect

    Chroneos, A.; Tahini, H. A.; Schwingenschlögl, U.; Grimes, R. W.

    2014-07-14

    Density functional based simulation, corrected for finite size effects, is used to investigate systematically the formation of antisite defects in III-V semiconductors (III = Al, Ga, and In and V = P, As, and Sb). Different charge states are modelled as a function of the Fermi level and under different growth conditions. The formation energies of group III antisites (III{sub V}{sup q}) decrease with increasing covalent radius of the group V atom though not group III radius, whereas group V antisites (V{sub III}{sup q}) show a consistent decrease in formation energies with increase in group III and group V covalent radii. In general, III{sub V}{sup q} defects dominate under III-rich conditions and V{sub III}{sup q} under V-rich conditions. Comparison with equivalent vacancy formation energy simulations shows that while antisite concentrations are always dominant under stoichiometric conditions, modest variation in growth or doping conditions can lead to a significantly higher concentration of vacancies.

  6. Thermal conductivity of III-V semiconductor superlattices

    SciTech Connect

    Mei, S. Knezevic, I.

    2015-11-07

    This paper presents a semiclassical model for the anisotropic thermal transport in III-V semiconductor superlattices (SLs). An effective interface rms roughness is the only adjustable parameter. Thermal transport inside a layer is described by the Boltzmann transport equation in the relaxation time approximation and is affected by the relevant scattering mechanisms (three-phonon, mass-difference, and dopant and electron scattering of phonons), as well as by diffuse scattering from the interfaces captured via an effective interface scattering rate. The in-plane thermal conductivity is obtained from the layer conductivities connected in parallel. The cross-plane thermal conductivity is calculated from the layer thermal conductivities in series with one another and with thermal boundary resistances (TBRs) associated with each interface; the TBRs dominate cross-plane transport. The TBR of each interface is calculated from the transmission coefficient obtained by interpolating between the acoustic mismatch model (AMM) and the diffuse mismatch model (DMM), where the weight of the AMM transmission coefficient is the same wavelength-dependent specularity parameter related to the effective interface rms roughness that is commonly used to describe diffuse interface scattering. The model is applied to multiple III-arsenide superlattices, and the results are in very good agreement with experimental findings. The method is both simple and accurate, easy to implement, and applicable to complicated SL systems, such as the active regions of quantum cascade lasers. It is also valid for other SL material systems with high-quality interfaces and predominantly incoherent phonon transport.

  7. Characterization of III-V materials by optical interferometry

    NASA Astrophysics Data System (ADS)

    Montgomery, P. C.; Vabre, P.; Montaner, D.; Fillard, J. P.

    1993-09-01

    Digital interference microscopy is a new measuring technique with submicron horizontal resolution and nanometric vertical resolution, that can be used for the three-dimensional analysis of surface defects and device features in many microelectronics applications on bulk materials and epitaxial layers. In this paper we show how certain defects can be analysed on III-V materials and devices using two different interferometric techniques. The choice of the technique depends on the height and the slope of the surface features to be measured. We show that small defects less than λ/2 in height, or surfaces with shallow continuous slopes upto one or two microns high are best profiled with the phase stepping technique (PSM) because of the high vertical resolution of 1 nm and the higher speed and precision. This is illustrated by studies of the surface polish of InP wafers, defects after chemical etching of tin doped InP, defects on an epitaxial layer of GaAs on InP and quantum dot structures on GaAs. For measuring devices which contain mesas and grooves with step heights greater than λ/2, the peak fringe scanning (PFSM) method is the better choice. The vertical resolution is slightly less (4 nm), but the vertical range is higher (upto 15 μm) as demonstrated with the measurement of an etched groove in a laser/detector device on a quaternary layer on InP, and a MESFET device on GaAs. Compared with electron microscopy and the new near field scanning techniques, digital interference microscopy has the advantages of ease of use and speed of analysis and being able to resolve certain problems that are difficult or not possible by other means, such as profiling deep narrow etched grooves, or measuring the relief of a surface hidden under a transparent layer. The main disadvantages are that the horizontal resolution is limited to the resolving power of the objective and that errors due to variations in the optical properties of the sample need to be taken into account. La

  8. Ultra-high-throughput Production of III-V/Si Wafer for Electronic and Photonic Applications

    NASA Astrophysics Data System (ADS)

    Geum, Dae-Myeong; Park, Min-Su; Lim, Ju Young; Yang, Hyun-Duk; Song, Jin Dong; Kim, Chang Zoo; Yoon, Euijoon; Kim, Sanghyeon; Choi, Won Jun

    2016-02-01

    Si-based integrated circuits have been intensively developed over the past several decades through ultimate device scaling. However, the Si technology has reached the physical limitations of the scaling. These limitations have fuelled the search for alternative active materials (for transistors) and the introduction of optical interconnects (called “Si photonics”). A series of attempts to circumvent the Si technology limits are based on the use of III-V compound semiconductor due to their superior benefits, such as high electron mobility and direct bandgap. To use their physical properties on a Si platform, the formation of high-quality III-V films on the Si (III-V/Si) is the basic technology ; however, implementing this technology using a high-throughput process is not easy. Here, we report new concepts for an ultra-high-throughput heterogeneous integration of high-quality III-V films on the Si using the wafer bonding and epitaxial lift off (ELO) technique. We describe the ultra-fast ELO and also the re-use of the III-V donor wafer after III-V/Si formation. These approaches provide an ultra-high-throughput fabrication of III-V/Si substrates with a high-quality film, which leads to a dramatic cost reduction. As proof-of-concept devices, this paper demonstrates GaAs-based high electron mobility transistors (HEMTs), solar cells, and hetero-junction phototransistors on Si substrates.

  9. Ultra-high-throughput Production of III-V/Si Wafer for Electronic and Photonic Applications

    PubMed Central

    Geum, Dae-Myeong; Park, Min-Su; Lim, Ju Young; Yang, Hyun-Duk; Song, Jin Dong; Kim, Chang Zoo; Yoon, Euijoon; Kim, SangHyeon; Choi, Won Jun

    2016-01-01

    Si-based integrated circuits have been intensively developed over the past several decades through ultimate device scaling. However, the Si technology has reached the physical limitations of the scaling. These limitations have fuelled the search for alternative active materials (for transistors) and the introduction of optical interconnects (called “Si photonics”). A series of attempts to circumvent the Si technology limits are based on the use of III-V compound semiconductor due to their superior benefits, such as high electron mobility and direct bandgap. To use their physical properties on a Si platform, the formation of high-quality III-V films on the Si (III-V/Si) is the basic technology ; however, implementing this technology using a high-throughput process is not easy. Here, we report new concepts for an ultra-high-throughput heterogeneous integration of high-quality III-V films on the Si using the wafer bonding and epitaxial lift off (ELO) technique. We describe the ultra-fast ELO and also the re-use of the III-V donor wafer after III-V/Si formation. These approaches provide an ultra-high-throughput fabrication of III-V/Si substrates with a high-quality film, which leads to a dramatic cost reduction. As proof-of-concept devices, this paper demonstrates GaAs-based high electron mobility transistors (HEMTs), solar cells, and hetero-junction phototransistors on Si substrates. PMID:26864968

  10. Growth far from equilibrium: Examples from III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Kuech, Thomas F.; Babcock, Susan E.; Mawst, Luke

    2016-12-01

    The development of new applications has driven the field of materials design and synthesis to investigate materials that are not thermodynamically stable phases. Materials which are not thermodynamically stable can be synthesized and used in many applications. These materials are kinetically stabilized during use. The formation of such metastable materials requires both an understanding of the associated thermochemistry and the key surface transport processes present during growth. Phase separation is most easily accomplished at the growth surface during synthesis where mass transport is most rapid. These surface transport processes are sensitive to the surface stoichiometry, reconstruction, and chemistry as well as the growth temperature. The formation of new metastable semiconducting alloys with compositions deep within a compositional miscibility gap serves as model systems for the understanding of the surface chemical and physical processes controlling their formation. The GaAs1-yBiy system is used here to elucidate the role of surface chemistry in the formation of a homogeneous metastable composition during the chemical vapor deposition of the alloy system.

  11. The Electronic and Electro-Optic Future of III-V Semiconductor Compounds.

    DTIC Science & Technology

    1978-12-01

    An assessment of material development of III-V compounds for electro - optic , microwave and millimeter wave technology is presented. Questions concerning material selection, needs and processing is addressed. (Author)

  12. Precise measurement of charged defects in III-V compounds (supplement 2)

    NASA Technical Reports Server (NTRS)

    Soest, J. F.

    1973-01-01

    Experimental methods and related theory which will permit the measurement of low concentrations of vacancies and other defects in III-V compound semiconductors are discussed. Once the nature of these defects has been determined, this information can be incorporated into a transport theory for devices constructed from these materials, and experiments conducted to test the theory. The vacancies and other defects in the III-V compounds are detected by measurement of the nuclear magnetic resonance (NMR) line width. Most of the III-V compounds have at least one isotope with a nuclear quadrupole moment. In a crystal with a cubic crystal field (characteristic of most III-V compounds) there is no quadrupole splitting of the Zeeman resonance line. However, a defect removes the cubic symmetry locally and causes splitting which result in a change of the NMR width. This change can be used to detect the presence of vacancies.

  13. Effects of Humidity on Non-Hermetically Packaged III-V Structures and Devices

    NASA Technical Reports Server (NTRS)

    Leon, R.; Martin, S.; Lee, T.; Okuno, J.; Ruiz, R.; Gauldin, R.; Gaidis, M.; Smith, R.

    1999-01-01

    High humidity and temperature test (known as 85/85 tests) were performed on various III-V devices and structures to determine environmental effects in non-hermetically packaged GaAs membrane mixer diodes.

  14. The coupling of thermochemistry and phase diagrams for group III-V semiconductor systems. Final report

    SciTech Connect

    Anderson, T.J.

    1998-07-21

    The project was directed at linking the thermochemical properties of III-V compound semiconductors systems with the reported phase diagrams. The solid-liquid phase equilibrium problem was formulated and three approaches to calculating the reduced standard state chemical potential were identified and values were calculated. In addition, thermochemical values for critical properties were measured using solid state electrochemical techniques. These values, along with the standard state chemical potentials and other available thermochemical and phase diagram data, were combined with a critical assessment of selected III-V systems. This work was culminated with a comprehensive assessment of all the III-V binary systems. A novel aspect of the experimental part of this project was the demonstration of the use of a liquid encapsulate to measure component activities by a solid state emf technique in liquid III-V systems that exhibit high vapor pressures at the measurement temperature.

  15. Growth and Characterization of III-V Nitride Quantum Dots and Quantum Wires

    DTIC Science & Technology

    2010-03-26

    REPORT Growth and Characterization of III - V Nitride Quantum Dots and Quantum Wires 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Our research program...ANSI Std. Z39.18 - 14-Sep-2009 Final report Growth and Characterization of III - V Nitride Quantum Dots and Quantum Wires Statement of the...has two interrelated components: the growth of GaN nanowires and the fabrication of electronic devices, including gas sensors, on these nanowires . A

  16. Imaging electron emission from diamond and III V nitride surfaces with photo-electron emission microscopy

    NASA Astrophysics Data System (ADS)

    Nemanich, R. J.; English, S. L.; Hartman, J. D.; Sowers, A. T.; Ward, B. L.; Ade, H.; Davis, R. F.

    1999-05-01

    Wide bandgap semiconductors such as diamond and the III-V nitrides (GaN, AlN, and AlGaN alloys) exhibit small or even negative electron affinities. Results have shown that different surface treatments will modify the electron affinity of diamond to cause a positive or negative electron affinity (NEA). This study describes the characterization of these surfaces with photo-electron emission microscopy (PEEM). The PEEM technique is unique in that it combines aspects of UV photoemission and field emission. In this study, PEEM images are obtained with either a traditional Hg lamp or with tunable UV excitation from a free electron laser. The UV-free electron laser at Duke University provides tunable emission from 3.5 to greater than 7 eV. PEEM images of boron or nitrogen (N)-doped diamond are similar to SEM of the same surface indicating relatively uniform emission. For the N-doped samples, PEEM images were obtained for different photon energies ranging from 5.0 to 6.0 eV. In these experiments, the hydrogen terminated surface showed more intense PEEM images at lower photon energy indicating a lower photothreshold than annealed surfaces which are presumed to be adsorbate free. For the nitrides, the emission properties of an array of GaN emitter structures is imaged. Emission is observed from the peaks, and relatively uniform emission is observed from the array. The field at the sample surface is approximately 10 V/μm which is sufficient to obtain an image without UV light. This process is termed field emission electron microscopy (FEEM).

  17. Structural and optical properties of II-VI and III-V compound semiconductors

    NASA Astrophysics Data System (ADS)

    Huang, Jingyi

    This dissertation is on the study of structural and optical properties of some III-V and II-VI compound semiconductors. The first part of this dissertation is a study of the deformation mechanisms associated with nanoindentation and nanoscratching of InP, GaN, and ZnO crystals. The second part is an investigation of some fundamental issues regarding compositional fluctuations and microstructure in GaInNAs and InAlN alloys. In the first part, the microstructure of (001) InP scratched in an atomic force microscope with a small diamond tip has been studied as a function of applied normal force and crystalline direction in order to understand at the nanometer scale the deformation mechanisms in the zinc-blende structure. TEM images show deeper dislocation propagation for scratches along <110> compared to <100>. High strain fields were observed in <100> scratches, indicating hardening due to locking of dislocations gliding on different slip planes. Reverse plastic flow have been observed in <110> scratches in the form of pop-up events that result from recovery of stored elastic strain. In a separate study, nanoindentation-induced plastic deformation has been studied in c-, a-, and m-plane ZnO single crystals and c-plane GaN respectively, to study the deformation mechanism in wurtzite hexagonal structures. TEM results reveal that the prime deformation mechanism is slip on basal planes and in some cases, on pyramidal planes, and strain built up along particular directions. No evidence of phase transformation or cracking was observed in both materials. CL imaging reveals quenching of near band-edge emission by dislocations. In the second part, compositional inhomogeneity in quaternary GaInNAs and ternary InAlN alloys has been studied using TEM. It is shown that exposure to antimony during growth of GaInNAs results in uniform chemical composition in the epilayer, as antimony suppresses the surface mobility of adatoms that otherwise leads to two-dimensional growth and

  18. Microstructural evaluation of heteroepitaxial III-V semiconductor thin films

    NASA Astrophysics Data System (ADS)

    Chen, Eric Brice

    Microstructural features of single and multilayered strained (In xGa1-xAs/GaAs, (Al)GaAs1-ySb y/GaAs) and unstrained (In0.49Ga0.51P/GaAs) heteroepitaxial structures were evaluated. During growth of a 1.5% mismatched InxGa 1-xAs layer on GaAs at 470°C, real-time multibeam optical stress sensor measurements revealed an unexpected shoulder in the strain-thickness profile. Real-time data was used to pause film growth at pre-determined stress-states surrounding the shoulder region (pre-, mid- and post-shoulder) to probe its origin. Dislocation structure of each stress-state was characterized by transmission electron microscopy. The shoulder coincided with reactions between 60° dislocations forming edge dislocations, suggesting an increased dislocation mobility which is required for multiplication. Dislocation half-loops were observed via cross-sectional microscopy, resulting in rapid relaxation of the film. In-graded (InxGa1-xAs) and Sb-graded (Al0.5Ga0.5As1-ySby, GaAs 1-ySby) compositionally step-graded multilayer buffers were analyzed to determine the optimal alloy for preventing the propagation of threading dislocations to the epitaxial surface. Multilayers were graded from a lattice parameter of 0.564 nm to 0.591 nm (4.6% mismatch) over a 1 mum film thickness. Threading dislocation density in the top-most layer of the Sb-graded structures (≤109 cm-2) was lower than the In-graded alloy (>1010 cm-2). In the InxGa1-xAs structure, threading dislocations were observed to congregate in discrete channels directly correlated to surface crosshatches. As/Sb compositional modulations in the Sb-graded structures reveal a more planar growth surface, preventing threading dislocation trapping. Characterization of dislocation structure indicated a directional asymmetry in the 60° and edge dislocation density for the GaAs1-ySb y multilayer. Replacing Ga with Al0.5Ga0.5 in the Sb-graded ternary improved planarity, resulting in a more uniform dislocation density. Residual strain

  19. III-V/Ge MOS device technologies for low power integrated systems

    NASA Astrophysics Data System (ADS)

    Takagi, S.; Noguchi, M.; Kim, M.; Kim, S.-H.; Chang, C.-Y.; Yokoyama, M.; Nishi, K.; Zhang, R.; Ke, M.; Takenaka, M.

    2016-11-01

    CMOS utilizing high mobility III-V/Ge channels on Si substrates is expected to be one of the promising devices for high performance and low power integrated systems in the future technology nodes, because of the enhanced carrier transport properties. In addition, Tunneling-FETs (TFETs) using Ge/III-V materials are regarded as one of the most important steep slope devices for the ultra-low power applications. In this paper, we address the device and process technologies of Ge/III-V MOSFETs and TFETs on the Si CMOS platform. The channel formation, source/drain (S/D) formation and gate stack engineering are introduced for satisfying the device requirements. The plasma post oxidation to form GeOx interfacial layers is a key gate stack technology for Ge CMOS. Also, direct wafer bonding of ultrathin body quantum well III-V-OI channels, combined with Tri-gate structures, realizes high performance III-V n-MOSFETs on Si. We also demonstrate planar-type InGaAs and Ge/strained SOI TFETs. The defect-less p+-n source junction formation with steep impurity profiles is a key for high performance TFET operation.

  20. Indium Zinc Oxide Mediated Wafer Bonding for III-V/Si Tandem Solar Cells

    SciTech Connect

    Tamboli, Adele C.; Essig, Stephanie; Horowitz, Kelsey A. W.; Woodhouse, Michael; van Hest, Maikel F. A. M.; Norman, Andrew G.; Steiner, Myles A.; Stradins, Paul

    2015-06-14

    Silicon-based tandem solar cells are desirable as a high efficiency, economically viable approach to one sun or low concentration photovoltaics. We present an approach to wafer bonded III-V/Si solar cells using amorphous indium zinc oxide (IZO) as an interlayer. We investigate the impact of a heavily doped III-V contact layer on the electrical and optical properties of bonded test samples, including the predicted impact on tandem cell performance. We present economic modeling which indicates that the path to commercial viability for bonded cells includes developing low-cost III-V growth and reducing constraints on material smoothness. If these challenges can be surmounted, bonded tandems on Si can be cost-competitive with incumbent PV technologies, especially in low concentration, single axis tracking systems.

  1. Methods for forming group III-V arsenide-nitride semiconductor materials

    NASA Technical Reports Server (NTRS)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    2000-01-01

    Methods are disclosed for forming Group III--arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  2. Relaxation Models of the (110) Zinc-Blende III-V Semiconductor Surfaces: Density Functional Study

    SciTech Connect

    Ye, H.; Chen, G.; Wu, Y.; Zhu, Y.; Wei, S. H.

    2008-11-01

    Clean III-V zinc-blende (110) surfaces are the most extensively studied semiconductor surface. For conventional III-V compounds such as GaAs and InP, the surface relaxation follows a bond rotation relaxation model. However, for III-nitrides recent study indicates that they follow a bond-constricting relaxation model. First-principles atom relaxation calculations are performed to explore the origin of the difference between the two groups of materials. By analyzing the individual shift trends and ionic properties of the top layer anions and cations, we attribute the difference between the conventional and nitride III-V compounds to the strong electronegativity of N, which leads to the s{sup 2}p{sup 3} pyramid bond angle to be larger than the ideal one in bulk (109.5{sup o}). The general trends of the atomic relaxation at the III-nitrides (110) surfaces are explained.

  3. Dislocation effects in FinFETs for different III-V compound semiconductors

    NASA Astrophysics Data System (ADS)

    Hur, Ji-Hyun; Jeon, Sanghun

    2016-04-01

    While Si-based devices are facing the limits of scaling, III-V materials, having high mobility, have attracted more and more attention. However, their advantages are obtained by ignoring the drawbacks of inevitably present dislocations. In this paper, we present a theoretical model that describes the degradation in carrier mobility caused by these inevitable charged dislocations in nanometer-sized, quantum-confined III-V compound semiconductor fin-shaped field effect transistors. We conclude that the Fermi-level pinning effect needs to be resolved to give carriers high enough energy (Fermi energy in the channel) to effectively ignore Coulomb scattering of charges at dislocations in a channel made by III-V compound semiconductors.

  4. III-V/Si wafer bonding using transparent, conductive oxide interlayers

    SciTech Connect

    Tamboli, Adele C. Hest, Maikel F. A. M. van; Steiner, Myles A.; Essig, Stephanie; Norman, Andrew G.; Bosco, Nick; Stradins, Paul; Perl, Emmett E.

    2015-06-29

    We present a method for low temperature plasma-activated direct wafer bonding of III-V materials to Si using a transparent, conductive indium zinc oxide interlayer. The transparent, conductive oxide (TCO) layer provides excellent optical transmission as well as electrical conduction, suggesting suitability for Si/III-V hybrid devices including Si-based tandem solar cells. For bonding temperatures ranging from 100 °C to 350 °C, Ohmic behavior is observed in the sample stacks, with specific contact resistivity below 1 Ω cm{sup 2} for samples bonded at 200 °C. Optical absorption measurements show minimal parasitic light absorption, which is limited by the III-V interlayers necessary for Ohmic contact formation to TCOs. These results are promising for Ga{sub 0.5}In{sub 0.5}P/Si tandem solar cells operating at 1 sun or low concentration conditions.

  5. III-V/Si on silicon-on-insulator platform for hybrid nanoelectronics

    SciTech Connect

    Prucnal, Slawomir Zhou, Shengqiang; Ou, Xin; Facsko, Stefan; Oskar Liedke, Maciej; Bregolin, Felipe; Liedke, Bartosz; Grebing, Jochen; Fritzsche, Monika; Hübner, Rene; Mücklich, Arndt; Rebohle, Lars; Skorupa, Wolfgang; Helm, Manfred; Turek, Marcin; Drozdziel, Andrzej

    2014-02-21

    The unique properties of SOI wafers enable the integration of heterogeneous materials with distinct functionalities in different layers. In particular, III-V compound semiconductors are very attractive for low-noise and high-speed electronic and photonic components integrated on a single chip. We have developed a CMOS compatible and fully integrated solution for the integration of III-V compound semiconductors with silicon technology for optoelectronic applications. InAs compound semiconductor nanostructures are synthesized in SOI wafers using the combined ion beam implantation and millisecond liquid-phase epitaxial growth. Optoelectronic and microstructural investigations carried out on implanted, annealed, and selectively etched samples confirm the formation of high-quality III-V compound semiconductor nanostructures.

  6. Heterogeneous integration of SiGe/Ge and III-V for Si photonics

    NASA Astrophysics Data System (ADS)

    Takenaka, Mitsuru; Kim, Younghyun; Han, Jaehoon; Kang, Jian; Ikku, Yuki; Cheng, Yongpeng; Park, Jinkwon; Takagi, Shinichi

    2016-05-01

    The heterogeneous integration of SiGe/Ge and III-V semiconductors gives us an opportunity to enhance functionalities of Si photonics platform through their superior material properties which lack in Si. In this paper we discuss what SiGe/Ge and III-V can bring to Si photonics. We have predicted that the light effective hole mass in strained SiGe results in the enhanced the free-carrier effects such as the plasma dispersion effect and free-carrier absorption. We observed significantly larger free-carrier absorption in the SiGe optical modulator than in the control Si device. By fabricating asymmetric Mach-Zehnder interferometer (MZI) SiGe optical modulators, the enhancement of the plasma dispersion effect in strained SiGe has been successfully demonstrated. Mid-infrared integrated photonics based on Ge waveguides on Si have also been investigated. Since Ge is transparent to the entire mid-infrared range, Ge photonic integrated circuits on the Ge-on-Insulator (GeOI) wafer are quite attractive. We have successfully fabricated the GeOI wafer with 2-μm-thick buried oxide (BOX) layer by wafer bonding. The passive waveguide components based on Ge strip waveguides have been demonstrated on the GeOI. We have also demonstrated carrier-injection Ge variable optical attenuators. We have proposed and investigate the III-V CMOS photonics platform by using the III-V on Insulator (IIIV- OI) on a Si wafer. The strong optical confinement in the III-V-OI enables us to achieve high-performance photonic devices. We have successfully demonstrated InGaAsP MZI optical switch with the low on-state crosstalk on the III-V-OI. Ultra-low dark current waveguide InGaAs PDs integrated with an InP grating coupler are also achieved.

  7. Silicon MCM substrates for integration of III-V photonic devices and CMOS IC`s

    SciTech Connect

    Seigal, P.; Carson, R.; Flores, R.; Rose, B.

    1993-07-01

    The progress made in advanced packaging development at Sandia National Laboratories for integration of III-V photonic devices and CMOS IC`s on Silicon MCM substrates for planar aid stacked applications will be reported. Studies to characterize precision alignment techniques using solder attach materials compatible with both silicon IC`s and III-V devices will be discussed. Examples of the use of back-side alignment and IR through-wafer inspection will be shown along with the extra processing steps that are used. Under bump metallurgy considerations are also addressed.

  8. Strain Engineering of Epitaxially Transferred, Ultrathin Layers of III-V Semiconductor on Insulator

    DTIC Science & Technology

    2011-01-01

    patterned width of 350 nm–5 m and wet etched using a mixture of citric acid 1 g/ml in de-ionized DI H2O and hydrogen peroxide 30% at 1:20 volume...Strain engineering of epitaxially transferred, ultrathin layers of III-V semiconductor on insulator Hui Fang,1,2,3 Morten Madsen,1,2,3 Carlo Carraro...10.1063/1.3537963 III-V compound semiconductors have been extensively explored in the recent years for energy-efficient and high- speed electronics due

  9. III-V/silicon germanium tandem solar cells on silicon substrates

    NASA Astrophysics Data System (ADS)

    Schmieder, Kenneth J.

    The development of a cost-effective high voltage tandem solar cell that can be grown directly on a silicon (Si) platform can lead to a 34% increase in efficiency over the present best monocrystalline Si laboratory device. III-V devices are known to yield some of the highest efficiencies in photovoltaics, but the high cost of lattice matched substrates and metal organic chemical vapor deposition (MOCVD) and device development make them prohibitively expensive in many markets. By utilizing silicon substrates and limiting the thickness of the III-V MOCVD material growth, this cost can be reduced. The leveraging technology of this initiative is a metamorphic silicon:germanium (SiGe) buffer between the silicon substrate and the active device layers. As developed by AmberWave Inc., it provides a low-dislocation interface for III-V nucleation and a high quality bottom cell grown by reduced pressure chemical vapor deposition (RPCVD). This research first reports on the theoretical limits of a III-V/SiGe tandem solar cell. Results will evaluate multiple III-V materials for the determination of optimal material composition to be lattice-matched with SiGe. Following this, a more complex device simulation, incorporating all major loss mechanisms, is accomplished in order to predict ideal efficiency targets and evaluate present experimental structures. Results demonstrate a robust model capable of simulating a wide range of binary and ternary III-V devices. Predictions show the capability of a tandem device operating at 32.5% 1-sun efficiency without requiring TDD improvement beyond that of the present SiGe layers. Following simulations, experimental III-V structures are grown via MOCVD and characterized, indicating successful process development for growth of III-V materials on the SiGe platform. This growth is then validated via the design and development of experimental solar device structures. Each iteration, beginning with the single-junction windowless GaAsP solar cell and

  10. Theory of hole mobility in strained Ge and III-V p-channel inversion layers with high-κ insulators

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Fischetti, M. V.; Sorée, B.; O'Regan, T.

    2010-12-01

    We present a comprehensive investigation of the low-field hole mobility in strained Ge and III-V (GaAs, GaSb, InSb, and In1-xGaxAs) p-channel inversion layers with both SiO2 and high-κ insulators. The valence (sub)band structure of Ge and III-V channels, relaxed and under biaxial strain (tensile and compressive) is calculated using an efficient self-consistent method based on the six-band k ṡp perturbation theory. The hole mobility is then computed using the Kubo-Greenwood formalism accounting for nonpolar hole-phonon scattering (acoustic and optical), surface roughness scattering, polar phonon scattering (III-Vs only), alloy scattering (alloys only) and remote phonon scattering, accounting for multisubband dielectric screening. As expected, we find that Ge and III-V semiconductors exhibit a mobility significantly larger than the "universal" Si mobility. This is true for MOS systems with either SiO2 or high-κ insulators, although the latter ones are found to degrade the hole mobility compared to SiO2 due to scattering with interfacial optical phonons. In addition, III-Vs are more sensitive to the interfacial optical phonons than Ge due to the existence of the substrate polar phonons. Strain—especially biaxial tensile stress for Ge and biaxial compressive stress for III-Vs (except for GaAs)—is found to have a significant beneficial effect with both SiO2 and HfO2. Among strained p-channels, InSb exhibits the largest mobility enhancement. In0.7Ga0.3As also exhibits an increased hole mobility compared to Si, although the enhancement is not as large. Finally, our theoretical results are favorably compared with available experimental data for a relaxed Ge p-channel with a HfO2 insulator.

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

    PubMed

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

    2014-09-22

    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.

  12. Heterointegration of III-V on silicon using a crystalline oxide buffer layer

    NASA Astrophysics Data System (ADS)

    Bhatnagar, K.; Rojas-Ramirez, J. S.; Contreras-Guerrero, R.; Caro, M.; Droopad, R.

    2015-09-01

    The integration of III-V compound semiconductors with Si can combine the cost advantage and maturity of Si technology with the superior performance of III-V materials. We have achieved the heteroepitaxial growth of III-V compound semiconductors on a crystalline SrTiO3 buffer layer grown on Si(0 0 1) substrates. A two-step growth process utilizing a high temperature nucleation layer of GaAs, followed by a low-temperature GaAs layer at a higher growth rate was employed to achieve highly crystalline thick GaAs layers on the SrTiO3/Si substrates with low surface roughness as seen by AFM. The effect of the GaAs nucleation layer on different surface terminations for the SrTiO3 layer was studied for both on axis and miscut wafers, which led to the conclusion that the Sr terminated surface on miscut substrates provides the best GaAs films. Using GaAs/STO/Si as virtual substrates, we have optimized the growth of high quality GaSb using the interfacial misfit (IMF) dislocation array technique. This work can lead to the possibility of realizing infrared detectors and next-generation high mobility III-V CMOS within the existing Si substrate infrastructure.

  13. Two Dimensional Effective Electron Mass at the Fermi Level in Quantum Wells of III-V, Ternary and Quaternary Semiconductors.

    PubMed

    Chakrabarti, S; Chatterjee, B; Debbarma, S; Ghatak, K P

    2015-09-01

    In this paper we study the influence of strong electric field on the two dimensional (2D)effective electron mass (EEM) at the Fermi level in quantum wells of III-V, ternary and quaternary semiconductors within the framework of k x p formalism by formulating a new 2D electron energy spectrum. It appears taking quantum wells of InSb, InAs, Hg(1-x)Cd(x)Te and In(1-x)Ga(x)As(1-y)P(y) lattice matched to InP as examples that the EEM increases with decreasing film thickness, increasing electric field and increases with increasing surface electron concentration exhibiting spikey oscillations because of the crossing over of the Fermi level by the quantized level in quantum wells and the quantized oscillation occurs when the Fermi energy touches the sub-band energy. The electric field makes the mass quantum number dependent and the oscillatory mass introduces quantum number dependent mass anisotropy in addition to energy. The EEM increases with decreasing alloy composition where the variations are totally band structure dependent. Under certain limiting conditions all the results for all the cases get simplified into the well-known parabolic energy bands and thus confirming the compatibility test. The content of this paper finds three applications in the fields of nano-science and technology.

  14. MBE growth technology for high quality strained III-V layers

    NASA Technical Reports Server (NTRS)

    Grunthaner, Frank J. (Inventor); Liu, John K. (Inventor); Hancock, Bruce R. (Inventor)

    1992-01-01

    III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group II and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation to low temperature, and to permit the film to relax to equilibrium. The method of the invention 1) minimizes starting step density on sample surface; 2) deposits InAs and GaAs using an interrupted growth mode (0.25 to 2 mono-layers at a time); 3) maintains the instantaneous surface stoichiometry during growth (As-stable for GaAs, In-stable for InAs); and 4) uses time-resolved RHEED to achieve aspects (1)-14 (3).

  15. Nucleation and initial radius of self-catalyzed III-V nanowires

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.; Borie, S.; Dagnet, T.; Reynes, L.; André, Y.; Gil, E.

    2017-02-01

    We treat theoretically the initial nucleation step of self-catalyzed III-V nanowires under simultaneously deposited group III and V vapor fluxes and with surface diffusion of a group III element. Our model is capable of describing the droplet size at which the very first nanowire monolayer nucleates depending on the element fluxes and surface temperature. This size determines the initial nanowire radius in growth techniques without pre-deposition of gallium. We show that useful self-catalyzed III-V nanowires can form only under the appropriately balanced V/III flux ratios and temperatures. Such balance is required to obtain nucleation from reasonably sized droplets that are neither too small under excessive arsenic flux nor too large in the arsenic-poor conditions.

  16. The Physics of III-V Heterojunction Devices in Wireless Communications

    NASA Astrophysics Data System (ADS)

    Johnson, Karl

    2003-03-01

    III-V heterojunction devices have become pervasive in wireless communication appliances. In particular, the low voltage, high efficiency power amplifier transmitters in cellular phones are dominated by heterojunction bipolar transistors (HBT), psuedomorphic high electron mobility transistors (pHEMT) and heterojunction field effect transistors (HFET). Further, these III-V heterojunction devices are also appearing in infrastructure applications such as cellular base stations, wireless local area network (WLAN) and cable television (CATV) line amplifiers. The design of these devices requires unique band gap engineering in order to meet the cost, performance and ruggedness in the linear and saturated power modes required by today's cellular modulation protocols. This presentation will address the physics behind the design, development and operation of these technologies leading to their optimization for the wireless market place.

  17. Thin-Film III V Photodetectors Integrated on Silicon-on-Insulator Photonic ICs

    NASA Astrophysics Data System (ADS)

    Brouckaert, Joost; Roelkens, Gunther; van Thourhout, Dries; Baets, Roel

    2007-04-01

    We critically assess recent progress in the integration of near-infrared photodetectors onto nanophotonic silicon-on-insulator (SOI) waveguide circuits. Integration of thin-film InGaAs photodetectors is studied in detail. This method consists of bonding unprocessed III V dies onto the SOI substrate using an intermediate adhesive layer. Both benzocyclobutene and spin-on glass are studied and compared as bonding agents. After the removal of the III V substrate, the thin-film detectors are fabricated using wafer-scale-compatible processes and lithographically aligned to the underlying SOI waveguides. The process is compatible with the fabrication of InP/InGaAsP laser diodes on SOI. A new design of an evanescently coupled metal semiconductor metal detector is proposed, proving the ability to obtain compact and highly efficient integrated InGaAs photodetectors.

  18. Efficient n-type doping of zinc-blende III-V semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Besteiro, Lucas V.; Tortajada, Luis; Souto, J.; Gallego, L. J.; Chelikowsky, James R.; Alemany, M. M. G.

    2014-03-01

    We demonstrate that it is preferable to dope III-V semiconductor nanowires by n-type anion substitution as opposed to cation substitution. Specifically, we show the dopability of zinc-blende nanowires is more efficient when the dopants are placed at the anion site as quantified by formation energies and the stabilization of DX-like defect centers. The comparison with previous work on n - type III-V semiconductor nanocrystals also allows to determine the role of dimensionality and quantum confinement on doping characteristics of materials. Our results are based on first-principles calculations of InP nanowires by using the PARSEC code. Work supported by the Spanish MICINN (FIS2012-33126) and Xunta de Galicia (GPC2013-043) in conjunction with FEDER. JRC acknowledges support from DoE (DE-FG02-06ER46286 and DESC0008877). Computational support was provided in part by CESGA.

  19. Electron microscopy techniques for evaluating epitaxial and bulk III-V compound semiconductors

    SciTech Connect

    Frigeri, C.

    1996-12-01

    Electron microscopy is an important technique to study interfaces and microdefects in advanced III-V compound semiconductors. The paper briefly reviews some of the TEM methods used to this purpose and shows examples of their application to the characterization of epitaxial structures such as InGaAs/GaAs and GaAs/Ge as well as processed substrates like implanted InP.

  20. Power-efficient III-V/silicon external cavity DBR lasers.

    PubMed

    Zilkie, A J; Seddighian, P; Bijlani, B J; Qian, W; Lee, D C; Fathololoumi, S; Fong, J; Shafiiha, R; Feng, D; Luff, B J; Zheng, X; Cunningham, J E; Krishnamoorthy, A V; Asghari, M

    2012-10-08

    We report the design and characterization of external-cavity DBR lasers built with a III-V-semiconductor reflective-SOA with spot-size converter edge-coupled to SOI waveguides containing Bragg grating mirrors. The un-cooled lasers have wall-plug-efficiencies of up to 9.5% at powers of 6 mW. The lasers are suitable for making power efficient, hybrid WDM transmitters in a CMOS-compatible SOI optical platform.

  1. To the understanding of the formation of the droplet-epitaxial III-V based nanostructures

    SciTech Connect

    Nemcsics, Ákos

    2014-05-15

    In this work, we discuss the evolution of the self-assembling III-V based nanostructures. These nano-structures were prepared by droplet epitaxial technique. The different nanostructures such as quantum dot, quantum ring, double quantum ring, or nanohole form similarly from an initial Ga droplet but under different substrate temperature and various arsenic pressures. Started from few atomic courses, we give here a qualitative description of the key processes for all of the aforementioned nanostructures.

  2. Process for forming shaped group III-V semiconductor nanocrystals, and product formed using process

    DOEpatents

    Alivisatos, A. Paul; Peng, Xiaogang; Manna, Liberato

    2001-01-01

    A process for the formation of shaped Group III-V semiconductor nanocrystals comprises contacting the semiconductor nanocrystal precursors with a liquid media comprising a binary mixture of phosphorus-containing organic surfactants capable of promoting the growth of either spherical semiconductor nanocrystals or rod-like semiconductor nanocrystals, whereby the shape of the semiconductor nanocrystals formed in said binary mixture of surfactants is controlled by adjusting the ratio of the surfactants in the binary mixture.

  3. Manipulating Surface States of III-V Nanowires with Uniaxial Stress.

    PubMed

    Signorello, G; Sant, S; Bologna, N; Schraff, M; Drechsler, U; Schmid, H; Wirths, S; Rossell, M D; Schenk, A; Riel, H

    2017-04-10

    III-V compound semiconductors are indispensable materials for today's high-end electronic and optoelectronic devices and are being explored for next-generation transistor logic and quantum technologies. III-V surfaces and interfaces play the leading role in determining device performance, and therefore, methods to control their electronic properties have been developed. Typically, surface passivation studies demonstrated how to limit the density of surface states. Strain has been widely used to improve the electronic transport properties and optoelectronic properties of III-Vs, but the potential of this technology to modify the surface properties still remains to be explored. Here we show that uniaxial stress induces a shift in the energy of the surface states of III-V nanowires, modifying their electronic properties. We demonstrate this phenomenon by modulating the conductivity of InAs nanowires over 4 orders of magnitude with axial strain ranging between -2.5% in compression and 2.1% in tension. The band bending at the surface of the nanostructure is modified from accumulation to depletion reversibly and reproducibly. We provide evidence of this physical effect using a combination of electrical transport measurement, Raman spectroscopy, band-structure modeling, and technology computer aided design (TCAD) simulations. With this methodology, the deformation potentials for the surface states are quantified. These results reveal that strain technology can be used to shift surface states away from energy ranges in which device performance is negatively affected and represent a novel route to engineer the electronic properties of III-V devices.

  4. Controlled formation of epitaxial III-V nanowires for device applications

    NASA Astrophysics Data System (ADS)

    Martensson, Thomas

    2007-03-01

    For the realization of devices with dimensions on the 10 nm scale, there is today a great interest in the possible use of self-assembly as a tool. In this talk will be described the state-of-the-art in growth of epitaxially nucleated, vertically standing semiconductor nanowires made from III-V semiconductors, with high level of control of dimensions, position and structural properties. Such wires hold great promise for use in future electronics and photonics applications. Three key aspects will be specifically addressed, namely: (1) The combination of top-down and bottom-up processes in lithographically aided formation of nanowires. A concern from industry is that bottom up techniques should suffer from ``fundamental placement problem[s], i.e. there is no practical and reliable way to precisely align and position them.'' (Chau R., et al. Opportunities and challenges of III-V nanoelectronics for future high-speed, low-power logic applications. (2005)). One way to resolve this issue is lithography where individual nanowire site control with high precision can be achieved. Electron beam lithography has the advantage of being a flexible high-resolution method, whereas nanoimprint lithography offers great opportunities for up-scaling and high-throughput processing. (2) The successful growth of III-V nanowires on silicon, including designed heterostructures. The special nanowire geometry with tens of nanometer radius and very small nanowire / substrate interface, enables monolithic integration of high-performance III-V materials on Silicon substrates. As an example, GaAsP heterostructure nanowires for photonic applications are discussed. Also the formation of InAs nanowires for high-speed and low-power-electronics directly on Si will be described. In the latter process, the use of foreign metal particles for wire growth is completely avoided, greatly reducing compatibility concerns between CMOS and nanowire technology. (3) Nanowire devices, such as field

  5. Understanding Self-Catalyzed Epitaxial Growth of III-V Nanowires toward Controlled Synthesis.

    PubMed

    Zi, Yunlong; Suslov, Sergey; Yang, Chen

    2017-02-08

    The self-catalyzed growth of III-V nanowires has drawn plenty of attention due to the potential of integration in current Si-based technologies. The homoparticle-assisted vapor-liquid-solid growth mechanism has been demonstrated for self-catalyzed III-V nanowire growth. However, the understandings of the preferred growth sites of these nanowires are still limited, which obstructs the controlled synthesis and the applications of self-catalyzed nanowire arrays. Here, we experimentally demonstrated that thermally created pits could serve as the preferred sites for self-catalyzed InAs nanowire growth. On that basis, we performed a pregrowth annealing strategy to promote the nanowire density by enhancing the pits formation on the substrate surface and enable the nanowire growth on the substrate that was not capable to facilitate the growth. The discovery of the preferred self-catalyzed nanowire growth sites and the pregrowth annealing strategy have shown great potentials for controlled self-catalyzed III-V nanowire array growth with preferred locations and density.

  6. III-V quantum light source and cavity-QED on silicon.

    PubMed

    Luxmoore, I J; Toro, R; Del Pozo-Zamudio, O; Wasley, N A; Chekhovich, E A; Sanchez, A M; Beanland, R; Fox, A M; Skolnick, M S; Liu, H Y; Tartakovskii, A I

    2013-01-01

    Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon's indirect band-gap. III-V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III-V material grown directly on silicon substrates. The high quality of the III-V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens-up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems.

  7. III/V nano ridge structures for optical applications on patterned 300 mm silicon substrate

    NASA Astrophysics Data System (ADS)

    Kunert, B.; Guo, W.; Mols, Y.; Tian, B.; Wang, Z.; Shi, Y.; Van Thourhout, D.; Pantouvaki, M.; Van Campenhout, J.; Langer, R.; Barla, K.

    2016-08-01

    We report on an integration approach of III/V nano ridges on patterned silicon (Si) wafers by metal organic vapor phase epitaxy (MOVPE). Trenches of different widths (≤500 nm) were processed in a silicon oxide (SiO2) layer on top of a 300 mm (001) Si substrate. The MOVPE growth conditions were chosen in a way to guarantee an efficient defect trapping within narrow trenches and to form a box shaped ridge with increased III/V volume when growing out of the trench. Compressively strained InGaAs/GaAs multi-quantum wells with 19% indium were deposited on top of the fully relaxed GaAs ridges as an active material for optical applications. Transmission electron microcopy investigation shows that very flat quantum well (QW) interfaces were realized. A clear defect trapping inside the trenches is observed whereas the ridge material is free of threading dislocations with only a very low density of planar defects. Pronounced QW photoluminescence (PL) is detected from different ridge sizes at room temperature. The potential of these III/V nano ridges for laser integration on Si substrates is emphasized by the achieved ridge volume which could enable wave guidance and by the high crystal quality in line with the distinct PL.

  8. High mobility CMOS technologies using III-V/Ge channels on Si platform

    NASA Astrophysics Data System (ADS)

    Takagi, S.; Kim, S.-H.; Yokoyama, M.; Zhang, R.; Taoka, N.; Urabe, Y.; Yasuda, T.; Yamada, H.; Ichikawa, O.; Fukuhara, N.; Hata, M.; Takenaka, M.

    2013-10-01

    MOSFETs using channel materials with high mobility and low effective mass have been regarded as strongly important for obtaining high current drive and low supply voltage CMOS under sub 10 nm regime. From this viewpoint, attentions have recently been paid to Ge and III-V channels. In this paper, possible solutions for realizing III-V/Ge MOSFETs on the Si platform are presented. The high quality III-V channel formation on Si substrates can be realized through direct wafer bonding. The gate stack formation is constructed on a basis of atomic layer deposition (ALD) Al2O3 gate insulators for both InGaAs and Ge MOSFETs. As the source/drain (S/D) formation, Ni-based metal S/D is implemented for both InGaAs and Ge MOSFETs. By combining these technologies, we demonstrate successful integration of InGaAs-OI nMOSFETs and Ge p-MOSFETs on a same wafer and their superior device performance.

  9. Transferable tight binding model for strained group IV and III-V heterostructures

    NASA Astrophysics Data System (ADS)

    Tan, Yaohua; Povolotskyi, Micheal; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

    Modern semiconductor devices have reached critical device dimensions in the range of several nanometers. For reliable prediction of device performance, it is critical to have a numerical efficient model that are transferable to material interfaces. In this work, we present an empirical tight binding (ETB) model with transferable parameters for strained IV and III-V group semiconductors. The ETB model is numerically highly efficient as it make use of an orthogonal sp3d5s* basis set with nearest neighbor inter-atomic interactions. The ETB parameters are generated from HSE06 hybrid functional calculations. Band structures of strained group IV and III-V materials by ETB model are in good agreement with corresponding HSE06 calculations. Furthermore, the ETB model is applied to strained superlattices which consist of group IV and III-V elements. The ETB model turns out to be transferable to nano-scale hetero-structure. The ETB band structures agree with the corresponding HSE06 results in the whole Brillouin zone. The ETB band gaps of superlattices with common cations or common anions have discrepancies within 0.05eV.

  10. Fatigue failure of concentrator III-V solar cells - Does forward bias current injection really kill III-V CPV cells?

    NASA Astrophysics Data System (ADS)

    Araki, Kenji; Nagai, Hirokazu; Tamura, Kazuyuki

    2012-10-01

    CPV cells are successively exposed by cycles of concentrated sunlight and huge cycling current flows out of contacts. The purpose of this research is to identify if the fatigue will be one of the life-end and wearing modes of CPV cells and how long the life-time will be. One of the best ways of giving cycling stress on cells and contacts is cycling forward bias injection. First, it is important to investigate if forward bias itself damages concentrator III-V cells. To confirm the forward bias current itself does not damage the CPV solar cells but cycling does, we applied 4 times of Isc continuously in 500 hours, equivalently total injection of 90,000 cycles, but no damage or degradation was observed. What's more, we applied the cycling test after the stress of 500 hour continuous forward bias injection. We did not identify any changes between groups of with stress of continuous forward bias and without them. On-Off tests giving forward bias current as high as 4 times of Isc are conducted. The failure was analyzed by the Weible function. About 2,000 cells in total were examined. A small number of initial failure, that of failure number of cycles lied along exponential distribution and distinct portion of wear mode failure that of failure number of cycles lied along Gaussian distribution were identified. The EL measurement indicated that all the damaged cells in wear mode were local shunt under the top contacts suggesting stress under the top contacts would be possibly responsible to the fatigue failure. Advanced contact design that leads to reduce the stress on the top contact is expected to prolong the lifetime of the III-V concentrator cells.

  11. Examination of the Ion Beam Response of III-V Semiconductor Substrates

    NASA Astrophysics Data System (ADS)

    Grossklaus, Kevin A.

    This work examines the response of the III-V materials to ion beam irradiation in a series of four experimental studies and describes the observed results in terms of the fundamental materials processes and properties that control ion-induced change in those compounds. Two studies investigate the use of Ga+ focused ion beam (FIB) irradiation of III-V substrate materials to create nanostructures. In the first, the creation of FIB induced group III nanodots on GaAs, InP, InAs, and AlAs is studied. The analysis of those results in terms of basic material properties and a simple nanodot growth model represents the first unified investigation of the fundamental processes that drive the nanodot forming behavior of the III-V compounds. The second nanostructure formation study reports the discovery and characterization of unique spike-like InAs nanostructures, termed "nanospikes," which may be useful for nanoscale electronic or thermoelectric applications. A novel method for controlling nanospike formation using InAs/InP heterostructures and film pre-patterning is developed, and the electrical properties of these ion erosion created nanostructures are characterized by in-situ TEM nanoprobe testing in a first-of-its-kind examination. The two remaining studies examine methods for using ion beam modification of III-V substrates to accommodate lattice-mismatched film growth with improved film properties. The first examines the effects of film growth on a wide range of different FIB created 3-D substrate patterns, and finds that 3-D surface features and patterns significantly alter film morphology and that growth on or near FIB irradiated regions does not improve film threading defect density. The second substrate modification study examines broad beam ion pre-implantation of GaAs wafers before InGaAs film growth, and is the first reported study of III-V substrate pre-implantation. Ar + pre-implantation was found to enhance the formation of threading defects in InGaAs films and

  12. Economic competitiveness of III-V on silicon tandem one-sun photovoltaic solar modules in favorable future scenarios: Economic competitiveness of III-V on on silicon tandem modules

    SciTech Connect

    Bobela, David C.; Gedvilas, Lynn; Woodhouse, Michael; Horowitz, Kelsey A. W.; Basore, Paul A.

    2016-09-05

    Tandem modules combining a III-V top cell with a Si bottom cell offer the potential to increase the solar energy conversion efficiency of one-sun photovoltaic modules beyond 25%, while fully utilizing the global investment that has been made in Si photovoltaics manufacturing. At present, the cost of III-V cells is far too high for this approach to be competitive for one-sun terrestrial power applications. We investigated the system-level economic benefits of both GaAs/Si and InGaP/Si tandem modules in favorable future scenarios where the cost of III-V cells is substantially reduced, perhaps to less than the cost of Si cells. We found, somewhat unexpectedly, that these tandems can reduce installed system cost only when the area-related balance-of-system cost is high, such as for area-constrained residential rooftop systems in the USA. When area-related balance-of-system cost is lower, such as for utility-scale systems, the tandem module offers no benefit. This is because a system using tandem modules is more expensive than one using single-junction Si modules when III-V cells are expensive, and a system using tandem modules is more expensive than one using single-junction III-V modules when III-V cells are inexpensive.

  13. III-V compound semiconductors for mass-produced nano-electronics: theoretical studies on mobility degradation by dislocation.

    PubMed

    Hur, Ji-Hyun; Jeon, Sanghun

    2016-02-25

    As silicon-based electronics approach the limit of scaling for increasing the performance and chip density, III-V compound semiconductors have started to attract significant attention owing to their high carrier mobility. However, the mobility benefits of III-V compounds are too easily accepted, ignoring a harmful effect of unavoidable threading dislocations that could fundamentally limit the applicability of these materials in nanometer-scale electronics. In this paper, we present a theoretical model that describes the degradation of carrier mobility by charged dislocations in quantum-confined III-V semiconductor metal oxide field effect transistors (MOSFETs). Based on the results, we conclude that in order for III-V compound MOSFETs to outperform silicon MOSFETs, Fermi level pinning in the channel should be eliminated for yielding carriers with high injection velocity.

  14. General theory of the transverse dielectric constant of III-V semiconducting compounds

    NASA Technical Reports Server (NTRS)

    Kahen, K. B.; Leburton, J. P.

    1985-01-01

    A general model of the transverse dielectric constant of III-V compounds is developed using a hybrid method which combines the kp method with a nonlocal pseudopotential calculation. In this method the Brillouin zone is partitioned into three regions by expanding the energy bands and matrix elements about the F, X, and L symmetry points. The real and imaginary parts of the dielectric constant are calculated as a sum of the individual contributions of each region. By using this partition method, it is possible to get good insight into the dependence of the dielectric constant on the shape of the band structure.

  15. Quantification of trap densities at dielectric/III-V semiconductor interfaces

    NASA Astrophysics Data System (ADS)

    Engel-Herbert, Roman; Hwang, Yoontae; Stemmer, Susanne

    2010-08-01

    High-frequency capacitance-voltage curves for capacitors with high-k gate dielectrics and III-V semiconductor channels are modeled. The model takes into account the low conduction band density of states, the nonparabolicity of the Γ valley, and the population of higher lying conduction band valleys. The model is used to determine interface trap densities (Dit) and band bending of HfO2/In0.53Ga0.47As interfaces with different Dit and with pinned and unpinned Fermi levels, respectively. Potential sources of errors in extracting Dit are discussed and criteria that establish unpinned interfaces are developed.

  16. Integrated Optical Pumping of Cr & Ti-Doped Sapphire Substrates With III-V Nitride Materials

    DTIC Science & Technology

    2005-08-24

    the Cr in sapphire could also permit the construction of white light LEDs . Ultimately, an integrated III-V Nitride optical pump for Ti:Sapphire could...substrates by MOCVD. 2. Characterization of doped sapphire/ InGaN structures byPL to simulate electrical injection by laser or LED device structures Part 2 1...Cr:sapphire substrate. Solid line is the spectrum of blue and red light emitted by InGaN LED epitaxially grown on Cr:sapphire substrate. The light was collected

  17. Heralded single-photon source in a III-V photonic crystal.

    PubMed

    Clark, Alex S; Husko, Chad; Collins, Matthew J; Lehoucq, Gaelle; Xavier, Stéphane; De Rossi, Alfredo; Combrié, Sylvain; Xiong, Chunle; Eggleton, Benjamin J

    2013-03-01

    In this Letter we demonstrate heralded single-photon generation in a III-V semiconductor photonic crystal platform through spontaneous four-wave mixing. We achieve a high brightness of 3.4×10(7) pairs·s(-1) nm(-1) W(-1) facilitated through dispersion engineering and the suppression of two-photon absorption in the gallium indium phosphide material. Photon pairs are generated with a coincidence-to-accidental ratio over 60 and a low g(2) (0) of 0.06 proving nonclassical operation in the single photon regime.

  18. Solid-state lighting : the III-V Epi Killer App.

    SciTech Connect

    Tsao, Jeffrey Yeenien

    2010-06-01

    Throughout its history, lighting technology has made tremendous progress: the efficiency with which power is converted into usable light has increased 2.8 orders of magnitude over three centuries. This progress has, in turn, fueled large increases in the consumption of light and productivity of human society. In this talk, we review an emerging new technology, solid-state lighting: its frontier performance potential; the underlying advances in physics and materials that might enable this performance potential; the resulting energy consumption and human productivity benefits; and the impact on worldwide III-V epi manufacture.

  19. Progress in the Development of Metamorphic Multi-Junction III-V Space-Solar Cells at Essential Research Incorporated

    NASA Technical Reports Server (NTRS)

    Sinharoy, Samar; Patton, Martin O.; Valko, Thomas M., Sr.; Weizer, Victor G.

    2002-01-01

    Theoretical calculations have shown that highest efficiency III-V multi-junction solar cells require alloy structures that cannot be grown on a lattice-matched substrate. Ever since the first demonstration of high efficiency metamorphic single junction 1.1 eV and 1.2 eV InGaAs solar cells by Essential Research Incorporated (ERI), interest has grown in the development of multi-junction cells of this type using graded buffer layer technology. ERI is currently developing a dual-junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air-mass zero (AM0), one-sun efficiency of 28%, and 100-sun efficiency of 37.5%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort at ERI involves the development of a 2.1 eV AlGaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple-junction concentrator tandem cell (projected practical AM0 efficiency of 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual-junction cell performance. In case of the triple-junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper.

  20. Techno-economic analysis of three different substrate removal and reuse strategies for III-V solar cells: Techno-economic analysis for III-V solar cells

    SciTech Connect

    Ward, J. Scott; Remo, Timothy; Horowitz, Kelsey; Woodhouse, Michael; Sopori, Bhushan; VanSant, Kaitlyn; Basore, Paul

    2016-05-10

    The high cost of wafers suitable for epitaxial deposition of III-V solar cells has been a primary barrier to widespread use of these cells in low-concentration and one-sun terrestrial solar applications. A possible solution is to reuse the substrate many times, thus spreading its cost across many cells. We performed a bottom-up techno-economic analysis of three different strategies for substrate reuse in high-volume manufacturing: epitaxial lift-off, spalling, and the use of a porous germanium release layer. The analysis shows that the potential cost reduction resulting from substrate reuse is limited in all three strategies--not by the number of reuse cycles achievable, but by the costs that are incurred in each cycle to prepare the substrate for another epitaxial deposition. The dominant substrate-preparation cost component is different for each of the three strategies, and the cost-ranking of these strategies is subject to change if future developments substantially reduce the cost of epitaxial deposition.

  1. Theoretical discovery of stable structures of group III-V monolayers: The materials for semiconductor devices

    SciTech Connect

    Suzuki, Tatsuo

    2015-11-23

    Group III-V compounds are very important as the materials of semiconductor devices. Stable structures of the monolayers of group III-V binary compounds have been discovered by using first-principles calculations. The primitive unit cell of the discovered structures is a rectangle, which includes four group-III atoms and four group-V atoms. A group-III atom and its three nearest-neighbor group-V atoms are placed on the same plane; however, these connections are not the sp{sup 2} hybridization. The bond angles around the group-V atoms are less than the bond angle of sp{sup 3} hybridization. The discovered structure of GaP is an indirect transition semiconductor, while the discovered structures of GaAs, InP, and InAs are direct transition semiconductors. Therefore, the discovered structures of these compounds have the potential of the materials for semiconductor devices, for example, water splitting photocatalysts. The discovered structures may become the most stable structures of monolayers which consist of other materials.

  2. Realization of III-V Semiconductor Periodic Nanostructures by Laser Direct Writing Technique

    NASA Astrophysics Data System (ADS)

    Huang, Yuan-qing; Huang, Rong; Liu, Qing-lu; Zheng, Chang-cheng; Ning, Ji-qiang; Peng, Yong; Zhang, Zi-yang

    2017-01-01

    In this paper, we demonstrated the fabrication of one-dimensional (1D) and two-dimensional (2D) periodic nanostructures on III-V GaAs substrates utilizing laser direct writing (LDW) technique. Metal thin films (Ti) and phase change materials (Ge2Sb2Te5 (GST) and Ge2Sb1.8Bi0.2Te5 (GSBT)) were chosen as photoresists to achieve small feature sizes of semiconductor nanostructures. A minimum feature size of about 50 nm about a quarter of the optical diffraction limit was obtained on the photoresists, and 1D III-V semiconductor nanolines with a minimum width of 150 nm were successfully acquired on the GaAs substrate which was smaller than the best results acquired on Si substrate ever reported. 2D nanosquare holes were fabricated as well by using Ti thin film as the photoresist, with a side width of about 200 nm, but the square holes changed to a rectangle shape when GST or GSBT was employed as the photoresist, which mainly resulted from the interaction of two cross-temperature fields induced by two scanning laser beams. The interacting mechanism of different photoresists in preparing periodic nanostructures with the LDW technique was discussed in detail.

  3. Realization of III-V Semiconductor Periodic Nanostructures by Laser Direct Writing Technique.

    PubMed

    Huang, Yuan-Qing; Huang, Rong; Liu, Qing-Lu; Zheng, Chang-Cheng; Ning, Ji-Qiang; Peng, Yong; Zhang, Zi-Yang

    2017-12-01

    In this paper, we demonstrated the fabrication of one-dimensional (1D) and two-dimensional (2D) periodic nanostructures on III-V GaAs substrates utilizing laser direct writing (LDW) technique. Metal thin films (Ti) and phase change materials (Ge2Sb2Te5 (GST) and Ge2Sb1.8Bi0.2Te5 (GSBT)) were chosen as photoresists to achieve small feature sizes of semiconductor nanostructures. A minimum feature size of about 50 nm about a quarter of the optical diffraction limit was obtained on the photoresists, and 1D III-V semiconductor nanolines with a minimum width of 150 nm were successfully acquired on the GaAs substrate which was smaller than the best results acquired on Si substrate ever reported. 2D nanosquare holes were fabricated as well by using Ti thin film as the photoresist, with a side width of about 200 nm, but the square holes changed to a rectangle shape when GST or GSBT was employed as the photoresist, which mainly resulted from the interaction of two cross-temperature fields induced by two scanning laser beams. The interacting mechanism of different photoresists in preparing periodic nanostructures with the LDW technique was discussed in detail.

  4. III-V/Si hybrid photonic devices by direct fusion bonding

    NASA Astrophysics Data System (ADS)

    Tanabe, Katsuaki; Watanabe, Katsuyuki; Arakawa, Yasuhiko

    2012-04-01

    Monolithic integration of III-V compound semiconductors on silicon is highly sought after for high-speed, low-power-consumption silicon photonics and low-cost, light-weight photovoltaics. Here we present a GaAs/Si direct fusion bonding technique to provide highly conductive and transparent heterojunctions by heterointerfacial band engineering in relation to doping concentrations. Metal- and oxide-free GaAs/Si ohmic heterojunctions have been formed at 300°C sufficiently low to inhibit active material degradation. We have demonstrated 1.3 μm InAs/GaAs quantum dot lasers on Si substrates with the lowest threshold current density of any laser on Si to date, and AlGaAs/Si dual-junction solar cells, by p-GaAs/p-Si and p-GaAs/n-Si bonding, respectively. Our direct semiconductor bonding technique opens up a new pathway for realizing ultrahigh efficiency multijunction solar cells with ideal bandgap combinations that are free from lattice-match restrictions required in conventional heteroepitaxy, as well as enabling the creation of novel high performance and practical optoelectronic devices by III-V/Si hybrid integration.

  5. A study of capping layers for sulfur monolayer doping on III-V junctions

    NASA Astrophysics Data System (ADS)

    Yum, J. H.; Shin, H. S.; Hill, R.; Oh, J.; Lee, H. D.; Mushinski, Ryan M.; Hudnall, Todd W.; Bielawski, C. W.; Banerjee, S. K.; Loh, W. Y.; Wang, Wei-E.; Kirsch, Paul

    2012-12-01

    Recently, high dosage doping on Si multi-gate field effect transistors and III-V planar structures using a self-limiting monolayer doping technique was reported to overcome challenges in scaling nano-sized transistors. The stoichiometry or composition of the capping layer was found to affect the diffusion efficiency of this process. In this work, we study the effect of a capping layer in sulfur monolayer doping on III-V junctions. Various capping temperatures and growth methods were compared. Based on the theoretical and experimental results, we suggest an optimized scheme consisting of a bi-layer capping structure. From Hall measurements and secondary ion mass spectrometry, a SiNx/BeO bi-layer capping, compared to single layer cap, exhibited the best results with a surface sheet resistance of 232 Ω/sq, junction depth of 11 nm, dopant profile abruptness of 3.5 nm/dec, electrically active S concentration of 4.9 × 1019/cm3 (=1.34 × 1013/cm2), and 3 times higher activation efficiency without significant transient-enhanced dopant diffusion.

  6. Band offsets of high K gate oxides on III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Robertson, J.; Falabretti, B.

    2006-07-01

    III-V semiconductors have high mobility and will be used in field effect transistors with the appropriate gate dielectric. The dielectrics must have band offsets over 1eV to inhibit leakage. The band offsets of various gate dielectrics including HfO2, Al2O3, Gd2O3, Si3N4, and SiO2 on III-V semiconductors such as GaAs, InAs, GaSb, and GaN have been calculated using the method of charge neutrality levels. Generally, the conduction band offsets are found to be over 1eV, so they should inhibit leakage for these dielectrics. On the other hand, SrTiO3 has minimal conduction band offset. The valence band offsets are also reasonably large, except for Si nitride on GaN and Sc2O3 on GaN which are 0.6-0.8eV. There is reasonable agreement with experiment where it exists, although the GaAs :SrTiO3 case is even worse in experiment.

  7. Calculation of the electron mobility in III-V inversion layers with high-κ dielectrics

    NASA Astrophysics Data System (ADS)

    O'Regan, T. P.; Fischetti, M. V.; Sorée, B.; Jin, S.; Magnus, W.; Meuris, M.

    2010-11-01

    We calculate the electron mobility for a metal-oxide-semiconductor system with a metallic gate, high-κ dielectric layer, and III-V substrate, including scattering with longitudinal-optical (LO) polar-phonons of the III-V substrate and with the interfacial excitations resulting from the coupling of insulator and substrate optical modes among themselves and with substrate plasmons. In treating scattering with the substrate LO-modes, multisubband dynamic screening is included and compared to the dielectric screening in the static limit and with the commonly used screening model obtained by defining an effective screening wave vector. The electron mobility components limited by substrate LO phonons and interfacial modes are calculated for In0.53Ga0.47As and GaAs substrates with SiO2 and HfO2 gate dielectrics. The mobility components limited by the LO-modes and interfacial phonons are also investigated as a function of temperature. Scattering with surface roughness, fixed interface charge, and nonpolar-phonons is also included to judge the relative impact of each scattering mechanism in the total mobility for In0.53Ga0.47As with HfO2 gate dielectric. We show that InGaAs is affected by interfacial-phonon scattering to an extent larger than Si, lowering the expected performance, but probably not enough to question the technological relevance of InGaAs.

  8. III-V/Si hybrid photonic devices by direct fusion bonding

    PubMed Central

    Tanabe, Katsuaki; Watanabe, Katsuyuki; Arakawa, Yasuhiko

    2012-01-01

    Monolithic integration of III-V compound semiconductors on silicon is highly sought after for high-speed, low-power-consumption silicon photonics and low-cost, light-weight photovoltaics. Here we present a GaAs/Si direct fusion bonding technique to provide highly conductive and transparent heterojunctions by heterointerfacial band engineering in relation to doping concentrations. Metal- and oxide-free GaAs/Si ohmic heterojunctions have been formed at 300°C; sufficiently low to inhibit active material degradation. We have demonstrated 1.3 μm InAs/GaAs quantum dot lasers on Si substrates with the lowest threshold current density of any laser on Si to date, and AlGaAs/Si dual-junction solar cells, by p-GaAs/p-Si and p-GaAs/n-Si bonding, respectively. Our direct semiconductor bonding technique opens up a new pathway for realizing ultrahigh efficiency multijunction solar cells with ideal bandgap combinations that are free from lattice-match restrictions required in conventional heteroepitaxy, as well as enabling the creation of novel high performance and practical optoelectronic devices by III-V/Si hybrid integration. PMID:22470842

  9. III-V nanocrystals capped with molecular metal chalcogenide ligands: high electron mobility and ambipolar photoresponse.

    PubMed

    Liu, Wenyong; Lee, Jong-Soo; Talapin, Dmitri V

    2013-01-30

    In this work, we synthesized InP and InAs nanocrystals (NCs) capped with different inorganic ligands, including various molecular metal chalcogenide complexes (MCCs) and chalcogenide ions. We found that MCCs and chalcogenide ions can quantitatively displace organic ligands from the surface of III-V NCs and serve as the inorganic capping groups for III-V NC surfaces. These inorganic ligands stabilize colloidal solutions of InP and InAs NCs in polar solvents and greatly facilitate charge transport between individual NCs. Charge transport studies revealed high electron mobility in the films of MCC-capped InP and InAs NCs. For example, we found that bridging InAs NCs with Cu(7)S(4)(-) MCC ligands can lead to very high electron mobility exceeding 15 cm(2)/(V s). In addition, we observed unprecedented ambipolar (positive/negative) photoresponse of MCC-capped InAs NC solids that changed sign depending on the ligand chemistry, illumination wavelength, and doping of the NC solid. For example, the sign of photoconductance of InAs NCs capped with Cu(7)S(4)(-) or Sn(2)S(6)(4-) ions converted from positive at 0.80 and 0.95 eV to negative at 1.27 and 1.91 eV. We propose an explanation of this unusually complex photoconductivity of InAs NC solids.

  10. Toward a III-V Multijunction Space Cell Technology on Si

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  11. Integrating III-V compound semiconductors with silicon using wafer bonding

    NASA Astrophysics Data System (ADS)

    Zhou, Yucai

    2000-12-01

    From Main Street to Wall Street, everyone has felt the effects caused by the Internet revolution. The Internet has created a new economy in the New Information Age and has brought significant changes in both business and personal life. This revolution has placed strong demands for higher bandwidth and higher computing speed due to high data traffic on today's information highway. In order to alleviate this problem, growing interconnection bottlenecks in digital designs have to be solved. The most feasible and practical way is to replace the conventional electrical interconnect with an optical interconnect. Since silicon does not have the optical properties necessary to accommodate these optical interconnect requirements, III-V based devices, most of which are GaAs-based or InP-based, must be intimately interconnected with the Si circuit at chip level. This monolithic integration technology enables the development of both intrachip and interchip optical connectors to take advantage of the enormous bandwidth provided by both high-performance very-large-scale integrated (VLSI) circuits and allied fiber and free-space optical technologies. However, lattice mismatch and thermal expansion mismatches between III-V materials and Si create enormous challenges for developing a feasible technology to tackle this problem. Among all the available approaches today, wafer bonding distinguishes itself as the most promising technology for integration due to its ability to overcome the constraints of both lattice constant mismatch and thermal expansion coefficient differences and even strain due to the crystal orientation. We present our development of wafer bonding technology for integrating III-V with Si in my dissertation. First, the pick-and-place multiple-wafer bonding technology was introduced. Then we systematically studied the wafer bonding of GaAs and InP with Si. Both high temperature wafer fusion and low/room temperature (LT/RT) wafer bonding have been investigated for

  12. Progressive materials integration: III-V on insulator by wafer bonding

    NASA Astrophysics Data System (ADS)

    Hayashi, Sumiko Lynn

    The development of wafer bonded III-V on insulator structures aims to provide advancements in high-speed electronic applications such as High Electron Mobility Transistors. This study demonstrates the feasibility of hydrogen exfoliated template layers for the growth III-V based device structures. InP layers are transferred to GaAs substrates to assess the suitability of the InP layer as a template for metal-organic vapor phase epitaxial growth. Strong, large area bonds between III-V wafers are achieved using SiN intermediate layers, which provide robust structures at high temperatures. The bonding mechanisms of SiN layers with a short oxygen plasma exposure are found to mimic those of SiO2. These bonds are strong enough to withstand thermal strain imposed by bonded wafers that exhibit appreciable coefficient of thermal expansion mismatch, such as InP and GaAs. These bonded wafers exhibit some stability against defect formation for low thermal strains. However, depending upon the thermal expansion coefficient mismatch and required thermal processing, misfit dislocations can form to relieve this thermal strain. Careful control of both template thickness and annealing temperatures leads to a stable template for subsequent epitaxial growth. Once bonding is complete, the template layer is separated from the bulk by a technique of hydrogen ion implantation and exfoliation. The layer exfoliation from a hydrogen implanted InP substrate is facilitated by the formation of extended defects in a certain temperature regime due to hydrogen trapping. Subsequently increasing the temperature produces rapid planar exfoliation. This two-step annealing scheme simultaneously allows the wafer bond to strengthen during the low temperature defect nucleation phase. After exfoliation, the surface of the template layer is generally very rough, therefore a chemical mechanical polishing step was developed to planarize this layer for subsequent epitaxial growth. Damage-free planarization of the

  13. Implications of the Differential Toxicological Effects of III-V Ionic and Particulate Materials for Hazard Assessment of Semiconductor Slurries.

    PubMed

    Jiang, Wen; Lin, Sijie; Chang, Chong Hyun; Ji, Zhaoxia; Sun, Bingbing; Wang, Xiang; Li, Ruibin; Pon, Nanetta; Xia, Tian; Nel, André E

    2015-12-22

    Because of tunable band gaps, high carrier mobility, and low-energy consumption rates, III-V materials are attractive for use in semiconductor wafers. However, these wafers require chemical mechanical planarization (CMP) for polishing, which leads to the generation of large quantities of hazardous waste including particulate and ionic III-V debris. Although the toxic effects of micron-sized III-V materials have been studied in vivo, no comprehensive assessment has been undertaken to elucidate the hazardous effects of submicron particulates and released III-V ionic components. Since III-V materials may contribute disproportionately to the hazard of CMP slurries, we obtained GaP, InP, GaAs, and InAs as micron- (0.2-3 μm) and nanoscale (<100 nm) particles for comparative studies of their cytotoxic potential in macrophage (THP-1) and lung epithelial (BEAS-2B) cell lines. We found that nanosized III-V arsenides, including GaAs and InAs, could induce significantly more cytotoxicity over a 24-72 h observation period. In contrast, GaP and InP particulates of all sizes as well as ionic GaCl3 and InCl3 were substantially less hazardous. The principal mechanism of III-V arsenide nanoparticle toxicity is dissolution and shedding of toxic As(III) and, to a lesser extent, As(V) ions. GaAs dissolves in the cell culture medium as well as in acidifying intracellular compartments, while InAs dissolves (more slowly) inside cells. Chelation of released As by 2,3-dimercapto-1-propanesulfonic acid interfered in GaAs toxicity. Collectively, these results demonstrate that III-V arsenides, GaAs and InAs nanoparticles, contribute in a major way to the toxicity of III-V materials that could appear in slurries. This finding is of importance for considering how to deal with the hazard potential of CMP slurries.

  14. Modeling of High-Frequency Noise in III-V Double-Gate HFETs

    NASA Astrophysics Data System (ADS)

    Vasallo, B. G.

    2009-04-01

    In this paper, we present a review of recent results on Monte Carlo modeling of high-frequency noise in III-V four-terminal devices. In particular, a study of the noise behavior of InAlAs/InGaAs Double-Gate High Electron Mobility Transistors (DG-HEMTs), operating in common mode, and Velocity Modulation Transistors (VMT), operating in differential mode, has been performed taking as a reference a similar standard HEMT. In the DG-HEMT, the intrinsic P, R and C parameters show a modest improvement, but the extrinsic minimum noise figure NFmin reveals a significantly better extrinsic noise performance due to the lower resistances of the gate contact and the source and drain accesses. In the VMT, very high values of P are obtained since the transconductance is very small, while the differential-mode operation leads to extremely low values of R.

  15. Seebeck Enhancement Through Miniband Conduction in III-V Semiconductor Superlattices at Low Temperatures

    NASA Astrophysics Data System (ADS)

    Bahk, Je-Hyeong; Sadeghian, Ramin Banan; Bian, Zhixi; Shakouri, Ali

    2012-06-01

    We present theoretically that the cross-plane Seebeck coefficient of InGaAs/InGaAlAs III-V semiconductor superlattices can be significantly enhanced through miniband transport at low temperatures. The miniband dispersion curves are calculated by self-consistently solving the Schrödinger equation with the periodic potential, and the Poisson equation taking into account the charge transfer between the two layers. Boltzmann transport in the relaxation-time approximation is used to calculate the thermoelectric transport properties in the cross-plane direction based on the modified density of states and group velocity. It is found that the cross-plane Seebeck coefficient can be enhanced more than 60% over the bulk values at an equivalent doping level at 80 K when the Fermi level is aligned at an edge of the minibands. Other thermoelectric transport properties are also calculated and discussed to further enhance the thermoelectric power factor.

  16. Heterogeneously integrated III-V/silicon dual-mode distributed feedback laser array for terahertz generation.

    PubMed

    Shao, Haifeng; Keyvaninia, Shahram; Vanwolleghem, Mathias; Ducournau, Guillaume; Jiang, Xiaoqing; Morthier, Geert; Lampin, Jean-Francois; Roelkens, Gunther

    2014-11-15

    We demonstrate an integrated distributed feedback (DFB) laser array as a dual-wavelength source for narrowband terahertz (THz) generation. The laser array is composed of four heterogeneously integrated III-V-on-silicon DFB lasers with different lengths enabling dual-mode lasing tolerant to process variations, bias fluctuations, and ambient temperature variations. By optical heterodyning the two modes emitted by the dual-wavelength DFB laser in the laser array using a THz photomixer composed of an uni-traveling carrier photodiode (UTC-PD), a narrow and stable carrier signal with a frequency of 0.357 THz is generated. The central operating frequency and the emitted terahertz wave linewidth are analyzed, along with their dependency on the bias current applied to the laser diode and ambient temperature.

  17. Lattice-Mismatched III-V Epilayers for High-Efficiency Photovoltaics

    SciTech Connect

    Ahrenkiel, Scott Phillip

    2013-06-30

    The project focused on development of new approaches and materials combinations to expand and improve the quality and versatility of lattice-mismatched (LMM) III-V semiconductor epilayers for use in high-efficiency multijunction photovoltaic (PV) devices. To address these goals, new capabilities for materials synthesis and characterization were established at SDSM&T that have applications in modern opto- and nano-electronics, including epitaxial crystal growth and transmission electron microscopy. Advances were made in analyzing and controlling the strain profiles and quality of compositional grades used for these technologies. In particular, quaternary compositional grades were demonstrated, and a quantitative method for characteristic X-ray analysis was developed. The project allowed enhanced collaboration between scientists at NREL and SDSM&T to address closely related research goals, including materials exchange and characterization.

  18. Density-functional calculations of carbon doping in III-V compound semiconductors

    NASA Astrophysics Data System (ADS)

    Latham, C. D.; Jones, R.; Öberg, S.; Briddon, P. R.

    2001-04-01

    This article reports the results of investigations based on local-density-functional theory into the relative formation energies for single substitutional carbon atoms in nine III-V compound semiconductors. The calculations are performed using a supercell formalism derived from the AIMPRO real-space cluster method. Only a very slight trend is discernible down the periodic table. When a metal atom is replaced with carbon, it is energetically least favorable in the phosphides, very marginally lower energy in the arsenides, and ~0.5-0.7 eV lower in the antimonides. The situation is approximately reversed when a P, As, or Sb atom is substituted by a C atom: for the In compounds the energy is ~0.4-0.8 eV higher than for the Al and Ga compounds.

  19. Design High-Efficiency III-V Nanowire/Si Two-Junction Solar Cell

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zhang, Y.; Zhang, D.; He, S.; Li, X.

    2015-06-01

    In this paper, we report the electrical simulation results of a proposed GaInP nanowire (NW)/Si two-junction solar cell. The NW physical dimensions are determined for optimized solar energy absorption and current matching between each subcell. Two key factors (minority carrier lifetime, surface recombination velocity) affecting power conversion efficiency (PCE) of the solar cell are highlighted, and a practical guideline to design high-efficiency two-junction solar cell is thus provided. Considering the practical surface and bulk defects in GaInP semiconductor, a promising PCE of 27.5 % can be obtained. The results depict the usefulness of integrating NWs to construct high-efficiency multi-junction III-V solar cells.

  20. New III-V cell design approaches for very high efficiency

    SciTech Connect

    Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; O'Bradovich, G.J.; Young, M.P. )

    1993-01-01

    This report describes progress during the first year of a three-year project. The objective of the research is to examine new design approaches for achieving very high conversion efficiencies. The program is divided into two areas. The first centers on exploring new thin-film approaches specifically designed for III-V semiconductors. The second area centers on exploring design approaches for achieving high conversion efficiencies without requiring extremely high quality material. Research activities consisted of an experimental study of minority carrier recombination in n-type, metal-organic chemical vapor deposition (MOCVD)-deposited GaAs, an assessment of the minority carrier lifetimes in n-GaAs grown by molecular beam epitaxy, and developing a high-efficiency cell fabrication process.

  1. Dilute Group III-V nitride intermediate band solar cells with contact blocking layers

    DOEpatents

    Walukiewicz, Wladyslaw [Kensington, CA; Yu, Kin Man [Lafayette, CA

    2012-07-31

    An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V.sub.OC) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

  2. Dilute group III-V nitride intermediate band solar cells with contact blocking layers

    DOEpatents

    Walukiewicz, Wladyslaw; Yu, Kin Man

    2015-02-24

    An intermediate band solar cell (IBSC) is provided including a p-n junction based on dilute III-V nitride materials and a pair of contact blocking layers positioned on opposite surfaces of the p-n junction for electrically isolating the intermediate band of the p-n junction by blocking the charge transport in the intermediate band without affecting the electron and hole collection efficiency of the p-n junction, thereby increasing open circuit voltage (V.sub.OC) of the IBSC and increasing the photocurrent by utilizing the intermediate band to absorb photons with energy below the band gap of the absorber layers of the IBSC. Hence, the overall power conversion efficiency of a IBSC will be much higher than an conventional single junction solar cell. The p-n junction absorber layers of the IBSC may further have compositionally graded nitrogen concentrations to provide an electric field for more efficient charge collection.

  3. Phase transitions in Group III-V and II-VI semiconductors at high pressure

    NASA Technical Reports Server (NTRS)

    Yu, S. C.; Liu, C. Y.; Spain, I. L.; Skelton, E. F.

    1979-01-01

    The structures and transition pressures of Group III-V and II-VI semiconductors and of a pseudobinary system (Ga/x/In/1-x/Sb) have been investigated. Results indicate that GaP, InSb, GaSb, GaAs and possible AlP assume Metallic structures at high pressures; a tetragonal, beta-Sn-like structure is adopted by only InSb and GaSb. The rocksalt phase is preferred in InP, InAs, AlSb, ZnO and ZnS. The model of Van Vechten (1973) gives transition pressures which are in good agreement with measured values, but must be refined to account for the occurrence of the ionic rocksalt structure in some compounds. In addition, discrepancies between the theoretical scaling values for volume changes at the semiconductor-to-metal transitions are observed.

  4. Dynamics of Wet Oxidation of High-AL-Content III-V Materials

    SciTech Connect

    Ashby, C.I.H.

    1999-01-27

    Oxidation of layers of high-Al-content III-V materials by water vapor has become the enabling process for high-efficiency vertical cavity surface emitting lasers (VCSELS) and has potential applications for reducing substrate current leakage in GaAs-on-insulator (GOI) MESFETS. Because of the established importance of wet oxidation in optoelectronic devices and its potential applications in electronic devices, it has become increasingly important to understand the mechanism of wet oxidation and how it might be expected to affect both the fabrication and subsequent operation of devices that have been made using this technique. The mechanism of wet oxidation and the consequence of this mechanism for heterostructure design and ultimate device operation are discussed here.

  5. Long-wave infrared (LWIR) detectors based on III-V materials

    NASA Technical Reports Server (NTRS)

    Maserjian, Joseph

    1991-01-01

    Future NASA missions for earth observation and planetary science require large photovoltaic detector arrays with high performance in the long wavelength region to 18 microns and at operating temperatures above 65 K where single-cycle long-life cryocoolers are being developed. Since these detector array requirements exceed the state of current HgCdTe technology, alternative detector materials are being investigated as a possible option for future missions. Advanced growth techniques (e.g., MBE and MOCVD) of column III-V semiconductors have opened opportunities for engineering new detector materials and device structures. The technical approaches under investigation at JPL (with university and industry participation) include: quantum well infrared photodetectors, heterojunction internal photoemission (HIP) photodetectors, type-II strained layer superlattices, and nipi doping superlattices. Each of these options are briefly described with some of their pros and cons. A more detailed description is given for the HIP approach being pioneered at JPL.

  6. Bismuth-induced surface structure and morphology in III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Duzik, Adam J.

    2015-04-01

    Bi is the largest group V element and has a number of advantages in III-V semiconductor properties, such as bandgap reduction, spin-orbit coupling, a preserved electron mobility over III-V-N materials, and nearly ideal surfactant properties resulting in a surface smoothing effect on GaAs. However, the mechanism for this behavior is not well understood. Insight on the mechanism is obtained through study of the Bi-terminated GaAs surface morphology and atomic reconstructions produced via molecular beam epitaxy (MBE). Experimental scanning tunneling microscopy (STM) characterization of the Bi/GaAs surface reveal disordered (1x3), (2x3), and (4x3) reconstructions, often sharing the same reflective high-energy electron diffraction (RHEED) patterns. Roughness on the micron length scale decreases as the step widen, attributed to the concurrent increase of opposite direction step edges on the nanometer length scale. Corresponding cluster expansion, density functional theory (DFT), and Monte Carlo simulations all point to the stability of the disordered (4x3) reconstruction at finite temperature as observed in experimental STM. The effects of incorporated Bi are determined through epitaxial GaSbBi growth on GaSb with various Ga:Sb:Bi flux ratios. Biphasic surface droplets are observed with sub-droplets, facets, and substrate etching. Despite the rough growth front, X-ray diffraction (XRD) and Rutherford backscatter (RBS) measurements show significant Bi incorporation of up to 12% into GaSb, along with a concurrent increase of background As concentration. This is attributed to a strain auto-compensation effect. Bi incorporation of up to 10% is observed for the highest Bi fluxes while maintaining low surface droplet density.

  7. Realization of back-side heterogeneous hybrid III-V/Si DBR lasers for silicon photonics

    NASA Astrophysics Data System (ADS)

    Durel, Jocelyn; Ferrotti, Thomas; Chantre, Alain; Cremer, Sébastien; Harduin, Julie; Bernabé, Stéphane; Kopp, Christophe; Boeuf, Frédéric; Ben Bakir, Badhise; Broquin, Jean-Emmanuel

    2016-02-01

    In this paper, the simulation, design and fabrication of a back-side coupling (BSC) concept for silicon photonics, which targets heterogeneous hybrid III-V/Si laser integration is presented. Though various demonstrations of a complete SOI integration of passive and active photonic devices have been made, they all feature multi-level planar metal interconnects, and a lack of integrated light sources. This is mainly due to the conflict between the need of planar surfaces for III-V/Si bonding and multiple levels of metallization. The proposed BSC solution to this topographical problem consists in fabricating lasers on the back-side of the Si waveguides using a new process sequence. The devices are based on a hybrid structure composed of an InGaAsP MQW active area and a Si-based DBR cavity. The emitted light wavelength is accordable within a range of 20 nm around 1.31μm thanks to thermal heaters and the laser output is fiber coupled through a Grating Coupler (GC). From a manufacturing point of view, the BSC approach provides not only the advantages of allowing the use of a thin-BOX SOI instead of a thick one; but it also shifts the laser processing steps and their materials unfriendly to CMOS process to the far back-end areas of fabrication lines. Moreover, aside from solving technological integration issues, the BSC concept offers several new design opportunities for active and passive devices (heat sink, Bragg gratings, grating couplers enhanced with integrated metallic mirrors, tapers…). These building boxes are explored here theoretically and experimentally.

  8. Advances in Single and Multijunction III-V Photovoltaics on Silicon for Space Power

    NASA Technical Reports Server (NTRS)

    Wilt, David M.; Fitzgerald, Eugene A.; Ringel, Steven A.

    2005-01-01

    A collaborative research effort at MIT, Ohio State University and NASA has resulted in the demonstration of record quality gallium arsenide (GaAs) based single junction photovoltaic devices on silicon (Si) substrates. The ability to integrate highly efficient, radiation hard III-V based devices on silicon offers the potential for dramatic reductions in cell mass (approx.2x) and increases in cell area. Both of these improvements offer the potential for dramatic reductions in the cost of on-orbit electrical power. Recently, lattice matched InGaP/GaAs and metamorphic InGaP/InGaAs dual junction solar cells were demonstrated by MBE and OMVPE, respectively. Single junction GaAs on Si devices have been integrated into a space flight experiment (MISSES), scheduled to be launched to the International Space Station in March of 2005. I-V performance data from the GaAs/Si will be collected on-orbit and telemetered to ground stations daily. Microcracks in the GaAs epitaxial material, generated because of differences in the thermal expansion coefficient between GaAs and Si, are of concern in the widely varying thermal environment encountered in low Earth orbit. Ground based thermal life cycling (-80 C to + 80 C) equivalent to 1 year in LEO has been conducted on GaAs/Si devices with no discernable degradation in device performance, suggesting that microcracks may not limit the ability to field GaAs/Si in harsh thermal environments. Recent advances in the development and testing of III-V photovoltaic devices on Si will be presented.

  9. Silicon/III-V laser with super-compact diffraction grating for WDM applications in electronic-photonic integrated circuits.

    PubMed

    Wang, Yadong; Wei, Yongqiang; Huang, Yingyan; Tu, Yongming; Ng, Doris; Lee, Cheewei; Zheng, Yunan; Liu, Boyang; Ho, Seng-Tiong

    2011-01-31

    We have demonstrated a heterogeneously integrated III-V-on-Silicon laser based on an ultra-large-angle super-compact grating (SCG). The SCG enables single-wavelength operation due to its high-spectral-resolution aberration-free design, enabling wavelength division multiplexing (WDM) applications in Electronic-Photonic Integrated Circuits (EPICs). The SCG based Si/III-V laser is realized by fabricating the SCG on silicon-on-insulator (SOI) substrate. Optical gain is provided by electrically pumped heterogeneous integrated III-V material on silicon. Single-wavelength lasing at 1550 nm with an output power of over 2 mW and a lasing threshold of around 150 mA were achieved.

  10. High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrator Application

    SciTech Connect

    Hubbard, Seth

    2012-09-12

    The High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrators project seeks to provide new photovoltaic cells for Concentrator Photovoltaics (CPV) Systems with higher cell efficiency, more favorable temperature coefficients and less sensitivity to changes in spectral distribution. The main objective of this project is to provide high efficiency III-V solar cells that will reduce the overall cost per Watt for power generation using CPV systems.This work is focused both on a potential near term application, namely the use of indium arsenide (InAs) QDs to spectrally "tune" the middle (GaAs) cell of a SOA triple junction device to a more favorable effective bandgap, as well as the long term goal of demonstrating intermediate band solar cell effects. The QDs are confined within a high electric field i-region of a standard GaAs solar cell. The extended absorption spectrum (and thus enhanced short circuit current) of the QD solar cell results from the increase in the sub GaAs bandgap spectral response that is achievable as quantum dot layers are introduced into the i-region. We have grown InAs quantum dots by OMVPE technique and optimized the QD growth conditions. Arrays of up to 40 layers of strain balanced quantum dots have been experimentally demonstrated with good material quality, low residual stain and high PL intensity. Quantum dot enhanced solar cells were grown and tested under simulated one sun AM1.5 conditions. Concentrator solar cells have been grown and fabricated with 5-40 layers of QDs. Testing of these devices show the QD cells have improved efficiency compared to baseline devices without QDs. Device modeling and measurement of thermal properties were performed using Crosslight APSYS. Improvements in a triple junction solar cell with the insertion of QDs into the middle current limiting junction was shown to be as high as 29% under one sun illumination for a 10 layer stack QD enhanced triple junction solar cell. QD devices have strong

  11. Analytical Electron Diffraction from Iii-V and II-Vi Semiconductors

    NASA Astrophysics Data System (ADS)

    Spellward, Paul

    Available from UMI in association with The British Library. This thesis describes the development and evaluation of a number of new TEM-based techniques for the measurement of composition in ternary III-V and II-VI semiconductors. New methods of polarity determination in binary and ternary compounds are also presented. The theory of high energy electron diffraction is outlined, with particular emphasis on zone axis diffraction from well-defined strings. An account of TEM microstructural studies of Cd_{rm x}Hg _{rm 1-x}Te and CdTe epitaxial layers, which provided the impetus for developing the diffraction-based analytical techniques, is given. The wide range of TEM-based compositional determination techniques is described. The use of HOLZ deficiency lines to infer composition from a lattice parameter measurement is evaluated. In the case of Cd_{ rm x}Hg_{rm 1-x}Te, it is found to be inferior to other techniques developed. Studies of dynamical aspects of HOLZ diffraction can yield information about the dispersion surface from which a measure of composition may be obtained. This technique is evaluated for Al_{rm x}Ga_{rm 1-x} As, in which it is found to be of some use, and for Cd_{rm x}Hg _{rm 1-x}Te, in which the large Debye-Waller factor associated with mercury in discovered to render the method of little value. A number of critical voltages may be measured in medium voltage TEMs. The (111) zone axis critical voltage of Cd_{rm x}Hg _{rm 1-x}Te is found to vary significantly with x and forms the basis of an accurate technique for composition measurement in that ternary compound. Other critical voltage phenomena are investigated. In Al _{rm x}Ga_ {rm 1-x}As and other light ternaries, a non-systematic critical voltage is found to vary with x, providing a good indicator of composition. Critical voltage measurements may be made by conventional CBED or by various other techniques, which may also simultaneously yield information on the spatial variation of composition. The

  12. Fabrication and photonics properties of III-V semiconductor nanowire structures

    NASA Astrophysics Data System (ADS)

    Lin, Tzu-ging

    III-V semiconductor nanowires (NWs) have shown great potential to be building blocks for optical, optoelectronic, and electronic devices due to their special transverse confinement of electrons and photons along the nanowire axis. In addition, semiconductor nanowires with subwavelength structures exhibit strong optical Mie resonance, making them ideal platforms for realizing novel optical devices, such as extreme solar energy absorbers and broadband light trapping devices. This special 1D optical Mie resonance can be enhanced by using semiconductor-core dielectric-shell (CS) and metal-core semiconductor-shell dielectric-outer shell (CSS) nanowire heterostructures. Those advantages can be even leveraged up by utilizing nanowire arrays, attributing to the increasing optical inter-wire interaction between incident light and nanostructures. However, to form a very thin, vertical IIIV nanowire array is challenging for both conventional top-down and bottom-up approaches due to the limitation of the resolution of lithographically defined masks and thermodynamic limits of growth direction and diameter of nanowires, respectively. By employing nanoscale self-mask effects, those limitations can be circumvented. In this dissertation, we presented a novel top-down etching method to fabricate very thin, high aspect ratio and vertical III-V nanowire arrays without lithographically defined masks. The mechanism of the formation of nanowire arrays was proposed and verified by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in this work. Optical characterizations, such as optical reflectance and Raman spectroscopy, were also performed on those nanowire arrays. By employing those nanowire arrays, broadband light trapping can be achieved. Besides, the effects of contact electrodes, such as indium tin oxide (ITO), silver, and copper, on semiconductor nanowire solar cell devices with different bandgaps were also investigated with a focus on optical

  13. Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

    NASA Astrophysics Data System (ADS)

    Campbell, Philip M.; Tarasov, Alexey; Joiner, Corey A.; Ready, W. Jud; Vogel, Eric M.

    2016-01-01

    Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs), separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.

  14. Band structure effects on resonant tunneling in III-V quantum wells versus two-dimensional vertical heterostructures

    SciTech Connect

    Campbell, Philip M.; Tarasov, Alexey; Joiner, Corey A.; Vogel, Eric M.; Ready, W. Jud

    2016-01-14

    Since the invention of the Esaki diode, resonant tunneling devices have been of interest for applications including multi-valued logic and communication systems. These devices are characterized by the presence of negative differential resistance in the current-voltage characteristic, resulting from lateral momentum conservation during the tunneling process. While a large amount of research has focused on III-V material systems, such as the GaAs/AlGaAs system, for resonant tunneling devices, poor device performance and device-to-device variability have limited widespread adoption. Recently, the symmetric field-effect transistor (symFET) was proposed as a resonant tunneling device incorporating symmetric 2-D materials, such as transition metal dichalcogenides (TMDs), separated by an interlayer barrier, such as hexagonal boron-nitride. The achievable peak-to-valley ratio for TMD symFETs has been predicted to be higher than has been observed for III-V resonant tunneling devices. This work examines the effect that band structure differences between III-V devices and TMDs has on device performance. It is shown that tunneling between the quantized subbands in III-V devices increases the valley current and decreases device performance, while the interlayer barrier height has a negligible impact on performance for barrier heights greater than approximately 0.5 eV.

  15. Ion implantation for high performance III-V JFETS and HFETS

    SciTech Connect

    Zolper, J.C.; Baca, A.G.; Sherwin, M.E.; Klem, J.F.

    1996-06-01

    Ion implantation has been an enabling technology for realizing many high performance electronic devices in III-V semiconductor materials. We report on advances in ion implantation processing for GaAs JFETs (joint field effect transistors), AlGaAs/GaAs HFETs (heterostructure field effect transistors), and InGaP or InAlP-barrier HFETs. The GaAs JFET has required the development of shallow p-type implants using Zn or Cd with junction depths down to 35 nm after the activation anneal. Implant activation and ionization issues for AlGaAs are reported along with those for InGaP and InAlP. A comprehensive treatment of Si-implant doping of AlGaAs is given based on donor ionization energies and conduction band density-of-states dependence on Al-composition. Si and Si+P implants in InGaP are shown to achieve higher electron concentrations than for similar implants in AlGaAs due to absence of the deep donor level. An optimized P co- implantation scheme in InGaP is shown to increase the implanted donor saturation level by 65%.

  16. Proton irradiation effects on advanced digital and microwave III-V components

    SciTech Connect

    Hash, G.L.; Schwank, J.R.; Shaneyfelt, M.R.; Sandoval, C.E.; Connors, M.P.; Sheridan, T.J.; Sexton, F.W.; Slayton, E.M.; Heise, J.A.; Foster, C.

    1994-09-01

    A wide range of advanced III-V components suitable for use in high-speed satellite communication systems were evaluated for displacement damage and single-event effects in high-energy, high-fluence proton environments. Transistors and integrated circuits (both digital and MMIC) were irradiated with protons at energies from 41 to 197 MeV and at fluences from 10{sup 10} to 2 {times} 10{sup 14} protons/cm{sup 2}. Large soft-error rates were measured for digital GaAs MESFET (3 {times} 10{sup {minus}5} errors/bit-day) and heterojunction bipolar circuits (10{sup {minus}5} errors/bit-day). No transient signals were detected from MMIC circuits. The largest degradation in transistor response caused by displacement damage was observed for 1.0-{mu}m depletion- and enhancement-mode MESFET transistors. Shorter gate length MESFET transistors and HEMT transistors exhibited less displacement-induced damage. These results show that memory-intensive GaAs digital circuits may result in significant system degradation due to single-event upset in natural and man-made space environments. However, displacement damage effects should not be a limiting factor for fluence levels up to 10{sup 14} protons/cm{sup 2} [equivalent to total doses in excess of 10 Mrad(GaAs)].

  17. Reliability of III-V electronic devices -- the defects that cause the trouble

    NASA Astrophysics Data System (ADS)

    Pantelides, Sokrates T.

    2012-02-01

    Degradation of electronic devices by hot electrons is universally attributed to the generation of defects, but the mechanisms for defect generation and the specific nature of the pertinent defects are not known for most systems. Here we describe three recent case studies [1] in III-V high-electron-mobility transistors that illustrate the power of combining density functional calculations and experimental data to identify the pertinent defects and associated degradation mechanisms. In all cases, benign pre-existing defects are either depassivated (irreversible degradation) or transformed to a metastable state (reversible degradation). This work was done in collaboration with R.D. Schrimpf, D.M. Fleetwood, Y. Puzyrev, X. Shen, T. Roy, S. DasGupta, and B.R. Tuttle. Devices were provided by D.F. Brown, J. Speck and U. Mishra, and by J. Bergman and B. Brar. [4pt] [1] Y. S. Puzyrev et al., Appl. Phys. Lett. 96, 053505 (2010); T. Roy et al., Appl. Phys. Lett. 96, 133503 (2010); X. Shen et al., J. Appl. Phys. 108, 114505 (2010).

  18. Theoretical performance of multi-junction solar cells combining III-V and Si materials.

    PubMed

    Mathews, Ian; O'Mahony, Donagh; Corbett, Brian; Morrison, Alan P

    2012-09-10

    A route to improving the overall efficiency of multi-junction solar cells employing conventional III-V and Si photovoltaic junctions is presented here. A simulation model was developed to consider the performance of several multi-junction solar cell structures in various multi-terminal configurations. For series connected, 2-terminal triple-junction solar cells, incorporating an AlGaAs top junction, a GaAs middle junction and either a Si or InGaAs bottom junction, it was found that the configuration with a Si bottom junction yielded a marginally higher one sun efficiency of 41.5% versus 41.3% for an InGaAs bottom junction. A significant efficiency gain of 1.8% over the two-terminal device can be achieved by providing an additional terminal to the Si bottom junction in a 3-junction mechanically stacked configuration. It is shown that the optimum performance can be achieved by employing a four-junction series-connected mechanically stacked device incorporating a Si subcell between top AlGaAs/GaAs and bottom In0.53Ga0.47As cells.

  19. Impact of photon recycling and luminescence coupling in III-V photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Walker, A. W.; Höhn, O.; Micha, D. N.; Wagner, L.; Helmers, H.; Bett, A. W.; Dimroth, F.

    2015-03-01

    Single junction photovoltaic devices composed of direct bandgap III-V semiconductors such as GaAs can exploit the effects of photon recycling to achieve record-high open circuit voltages. Modeling such devices yields insight into the design and material criteria required to achieve high efficiencies. For a GaAs cell to reach 28 % efficiency without a substrate, the Shockley-Read-Hall (SRH) lifetimes of the electrons and holes must be longer than 3 μs and 100 ns respectively in a 2 μm thin active region coupled to a very high reflective (>99%) rear-side mirror. The model is generalized to account for luminescence coupling in tandem devices, which yields direct insight into the top cell's non-radiative lifetimes. A heavily current mismatched GaAs/GaAs tandem device is simulated and measured experimentally as a function of concentration between 3 and 100 suns. The luminescence coupling increases from 14 % to 33 % experimentally, whereas the model requires an increasing SRH lifetime for both electrons and holes to explain these experimental results. However, intermediate absorbing GaAs layers between the two sub-cells may also increasingly contribute to the luminescence coupling as a function of concentration.

  20. Electrical and optical conductivities of hole gas in p-doped bulk III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Mawrie, Alestin; Halder, Pushpajit; Ghosh, Barun; Ghosh, Tarun Kanti

    2016-09-01

    We study electrical and optical conductivities of hole gas in p-doped bulk III-V semiconductors described by the Luttinger Hamiltonian. We provide exact analytical expressions of the Drude conductivity, inverse relaxation time for various impurity potentials, Drude weight, and optical conductivity in terms of the Luttinger parameters γ1 and γ2. The back scattering is completely suppressed as a result of the helicity conservation of the heavy and light hole states. The energy dependence of the relaxation time for the hole states is different from the Brooks-Herring formula for electron gas in n-doped semiconductors. We find that the inverse relaxation time of heavy holes is much less than that of the light holes for Coulomb-type and Gaussian-type impurity potentials and vice-versa for a short-range impurity potential. The Drude conductivity increases non-linearly with the increase in the hole density. The exponent of the density dependence of the conductivity is obtained in the Thomas-Fermi limit. The Drude weight varies linearly with the density even in the presence of the spin-orbit coupling. The finite-frequency optical conductivity goes as √{ ω} , and its amplitude strongly depends on the Luttinger parameters. The Luttinger parameters can be extracted from the optical conductivity measurement.

  1. Mapping the effective mass of electrons in III-V semiconductor quantum confined structures

    NASA Astrophysics Data System (ADS)

    Gass, M. H.; Papworth, A. J.; Beanland, R.; Bullough, T. J.; Chalker, P. R.

    2006-01-01

    The electron effective mass me* can be calculated from the Kramers-Kronig transformation of electron energy loss spectra (EELS) for III-V semiconductor materials. The mapping capabilities of a scanning transmission electron microscope, equipped with a GatanEnfina™ EELS system are exploited to produce maps showing the variation of me* with nanometer scale resolution for a range of semiconductors. The analysis was carried out on three material systems: a GaInNAs quantum well in a GaAs matrix; InAs quantum dots in a GaAs matrix, and bulk wurzitic GaN. Values of me* were measured as ˜0.07m0 for GaAs and 0.183m0 for GaN, both in excellent agreement with the literature. It has also been shown that the high frequency dielectric constant can be calculated using the Kramers-Kronig methodology. When the high frequency dielectric constant is incorporated into the calculations a much more accurate visual representation of me* is displayed in the maps.

  2. Spin Relaxation in III-V Semiconductors in various systems: Contribution of Electron-Electron Interaction

    NASA Astrophysics Data System (ADS)

    Dogan, Fatih; Kesserwan, Hasan; Manchon, Aurelien

    2015-03-01

    In spintronics, most of the phenomena that we are interested happen at very fast time scales and are rich in structure in time domain. Our understanding, on the other hand, is mostly based on energy domain calculations. Many of the theoretical tools use approximations and simplifications that can be perceived as oversimplifications. We compare the structure, material, carrier density and temperature dependence of spin relaxation time in n-doped III-V semiconductors using Elliot-Yafet (EY) and D'yakanov-Perel'(DP) with real time analysis using kinetic spin Bloch equations (KSBE). The EY and DP theories fail to capture details as the system investigated is varied. KSBE, on the other hand, incorporates all relaxation sources as well as electron-electron interaction which modifies the spin relaxation time in a non-linear way. Since el-el interaction is very fast (~ fs) and spin-conserving, it is usually ignored in the analysis of spin relaxation. Our results indicate that electron-electron interaction cannot be neglected and its interplay with the other (spin and momentum) relaxation mechanisms (electron-impurity and electron-phonon scattering) dramatically alters the resulting spin dynamics. We use each interaction explicitly to investigate how, in the presence of others, each relaxation source behaves. We use GaAs and GaN for zinc-blend structure, and GaN and AlN for the wurtzite structure.

  3. Analysis of III-V Superlattice nB n Device Characteristics

    NASA Astrophysics Data System (ADS)

    Rhiger, David R.; Smith, Edward P.; Kolasa, Borys P.; Kim, Jin K.; Klem, John F.; Hawkins, Samuel D.

    2016-09-01

    Mid-wavelength infrared nB n detectors built with III-V superlattice materials have been tested by means of both capacitance and direct-current methods. By combining the results, it is possible to achieve clear separation of the two components of dark current, namely the generation-recombination (GR) current due to the Shockley-Read-Hall mechanism in the depletion region, and the diffusion current from the neutral region. The GR current component is unambiguously identified by two characteristics: (a) it is a linear function of the depletion width, and (b) its activation energy is approximately one-half the bandgap. The remaining current is shown to be due to diffusion because of its activation energy equaling the full bandgap. In addition, the activation energy of the total measured dark current in each local region of the temperature-bias parameter space is evaluated. We show the benefits of capacitance analysis applied to the nB n device and review some of the requirements for correct measurements. The carrier concentration of the unintentionally doped absorber region is found to be 1.2 × 1014 cm-3 n-type. It is shown that the depletion region resides almost entirely within the absorber. Also, the doping in the nB n barrier is found to be 4 × 1015 cm-3 p-type. Minority-carrier lifetimes estimated from the dark current components are on the order of 10 μs.

  4. Novel planarization and passivation in the integration of III-V semiconductor devices

    NASA Astrophysics Data System (ADS)

    Zheng, Jun-Fei; Hanberg, Peter J.; Demir, Hilmi V.; Sabnis, Vijit A.; Fidaner, Onur; Harris, James S., Jr.; Miller, David A. B.

    2004-06-01

    III-V semiconductor devices typically use structures grown layer-by-layer and require passivation of sidewalls by vertical etching to reduce leakage current. The passivation is conventionally achieved by sealing the sidewalls using polymer and the polymer needs to be planarized by polymer etch-back method to device top for metal interconnection. It is very challenging to achieve perfect planarization needed for sidewalls of all the device layers including the top layer to be completely sealed. We introduce a novel hard-mask-assisted self-aligned planarization process that allows the polymer in 1-3 μm vicinity of the devices to be planarized perfectly to the top of devices. The hard-mask-assisted process also allows self-aligned via formation for metal interconnection to device top of μm size. The hard mask is removed to expose a very clean device top surface for depositing metals for low ohmic contact resistance metal interconnection. The process is robust because it is insensitive to device height difference, spin-on polymer thickness variation, and polymer etch non-uniformity. We have demonstrated high yield fabrication of monolithically integrated optical switch arrays with mesa diodes and waveguide electroabsorption modulators on InP substrate with yield > 90%, high breakdown voltage of > 15 Volts, and low ohmic contact resistance of 10-20 Ω.

  5. Epitaxial growth of three dimensionally structured III-V photonic crystal via hydride vapor phase epitaxy

    SciTech Connect

    Zheng, Qiye; Kim, Honggyu; Zhang, Runyu; Zuo, Jianmin; Braun, Paul V.; Sardela, Mauro; Balaji, Manavaimaran; Lourdudoss, Sebastian; Sun, Yan-Ting

    2015-12-14

    Three-dimensional (3D) photonic crystals are one class of materials where epitaxy, and the resultant attractive electronic properties, would enable new functionalities for optoelectronic devices. Here we utilize self-assembled colloidal templates to fabricate epitaxially grown single crystal 3D mesostructured Ga{sub x}In{sub 1−x}P (GaInP) semiconductor photonic crystals using hydride vapor phase epitaxy (HVPE). The epitaxial relationship between the 3D GaInP and the substrate is preserved during the growth through the complex geometry of the template as confirmed by X-ray diffraction (XRD) and high resolution transmission electron microscopy. XRD reciprocal space mapping of the 3D epitaxial layer further demonstrates the film to be nearly fully relaxed with a negligible strain gradient. Fourier transform infrared spectroscopy reflection measurement indicates the optical properties of the photonic crystal which agree with finite difference time domain simulations. This work extends the scope of the very few known methods for the fabrication of epitaxial III-V 3D mesostructured materials to the well-developed HVPE technique.

  6. Positron annihilation studies of defects in molecular beam epitaxy grown III-V layers

    SciTech Connect

    Umlor, M.T.; Keeble, D.J.; Asoka-Kumar, P.; Lynn, K.G.; Cooke, P.W.

    1994-08-01

    A summary of recent positron annihilation experiments on molecular beam epitaxy (MBE) grown III-V layers is Presented. Variable energy positron beam measurements on Al{sub 0.32}Ga{sub 0.68}As undoped and Si doped have been completed. Positron trapping at a open volume defect in Al{sub 0.32}Ga{sub 0.68}:Si for temperatures from 300 to 25 K in the dark was observed. The positron trap was lost after 1.3 eV illumination at 25K. These results indicate an open volume defect is associated with the local structure of the deep donor state of the DX center. Stability of MBE GaAs to thermal annealing war, investigated over the temperature range of 230 to 700{degrees}C, Proximity wafer furnace anneals in flowing argon were used, Samples grown above 450{degrees}C were shown to be stable but for sample below this temperature an anneal induced vacancy related defect was produced for anneals between 400 and 500{degrees}C. The nature of the defect was shown to be different for material grown at 350 and 230{degrees}C. Activation energies of 2.5 eV to 2.3 eV were obtained from isochronal anneal experiments for samples grown at 350 and 230{degrees}C, respectively.

  7. Electroless Deposition of III-V Semiconductor Nanostructures from Ionic Liquids at Room Temperature.

    PubMed

    Lahiri, Abhishek; Borisenko, Natalia; Olschewski, Mark; Gustus, René; Zahlbach, Janine; Endres, Frank

    2015-09-28

    Group III-V semiconductor nanostructures are important materials in optoelectronic devices and are being researched in energy-related fields. A simple approach for the synthesis of these semiconductors with well-defined nanostructures is desired. Electroless deposition (galvanic displacement) is a fast and versatile technique for deposition of one material on another and depends on the redox potentials of the two materials. Herein we show that GaSb can be directly synthesized at room temperature by galvanic displacement of SbCl3 /ionic liquid on electrodeposited Ga, on Ga nanowires, and also on commercial Ga. In situ AFM revealed the galvanic displacement process of Sb on Ga and showed that the displacement process continues even after the formation of GaSb. The bandgap of the deposited GaSb was 0.9±0.1 eV compared to its usual bandgap of 0.7 eV. By changing the cation in the ionic liquid, the redox process could be varied leading to GaSb with different optical properties.

  8. Laser field induced optical gain in a group III-V quantum wire

    NASA Astrophysics Data System (ADS)

    Saravanan, Subramanian; Peter, Amalorpavam John; Lee, Chang Woo

    2016-08-01

    Effect of intense high frequency laser field on the electronic and optical properties of heavy hole exciton in an InAsP/InP quantum well wire is investigated taking into consideration of the spatial confinement. Laser field induced exciton binding energies, optical band gap, oscillator strength and the optical gain in the InAs0.8P0.2/InP quantum well wire are studied. The variational formulism is applied to find the respective energies. The laser field induced optical properties are studied. The optical gain as a function of photon energy, in the InAs0.8P0.2/InP quantum wire, is obtained in the presence of intense laser field. The compact density matrix method is employed to obtain the optical gain. The results show that the 1.55 μm wavelength for the fibre optic telecommunication applications is achieved for 45 Å wire radius in the absence of laser field intensity whereas the 1.55 μm wavelength is obtained for 40 Å if the amplitude of the laser field amplitude parameter is 50 Å. The characterizing wavelength for telecommunication network is optimized when the intense laser field is applied for the system. It is hoped that the obtained optical gain in the group III-V narrow quantum wire can be applied for fabricating laser sources for achieving the preferred telecommunication wavelength.

  9. High Resolution Double Crystal X-Ray Diffractometry and Topography of Iii-V Semiconductor Compounds

    NASA Astrophysics Data System (ADS)

    Cockerton, Simon

    Available from UMI in association with The British Library. Requires signed TDF. Double crystal diffractometry and topography are now routinely used in many laboratories for the inspection of epitaxially grown devices. However the trend towards thinner layers and more complex structures requires the continual development of novel approaches using these techniques. This thesis is concerned with the development of these approaches to study the structural uniformity of semiconductor materials. The uniformity of large single crystals of lithium niobate has been studied using synchrotron radiation and double crystal X-ray topography. This study has shown a variety of contrast features including low angle grain boundaries and non-uniform dislocation densities. The abruptness of an interface between a layer and the underlying substrate has been studied using glancing incidence asymmetric reflections. Comparisons to simulated structures revealed that a closer match was achieved by the inclusion of a highly mismatched interfacial layer. This study illustrates the need for careful comparison between experimental and simulated rocking curves as different structures may produce very similar rocking curves. A double crystal topographic study of a AlGaAs laser structure revealed X-ray interference fringes. These are shown to be produced from the interaction of two simultaneously diffracting layers separated by a thin layer. Possible formation mechanisms have been discussed showing that these fringes are capable of revealing changes in the active layer at the atomic level. A novel approach has also been developed using synchrotron radiation to study the non -stoichiometry of GaAs. This approach uses the quasi-forbidden reflections which are present in III-V semiconductors due to the differences in the atomic scattering factors. This study has also discussed the behaviour of strong and weak reflections in the region of absorption edges and modelled their behaviour using the

  10. Integrating III-V, Si, and polymer waveguides for optical interconnects: RAPIDO

    NASA Astrophysics Data System (ADS)

    Aalto, Timo; Harjanne, Mikko; Offrein, Bert-Jan; Caër, Charles; Neumeyr, Christian; Malacarne, Antonio; Guina, Mircea; Sheehan, Robert N.; Peters, Frank H.; Melanen, Petri

    2016-03-01

    We present a vision for the hybrid integration of advanced transceivers at 1.3 μm wavelength, and the progress done towards this vision in the EU-funded RAPIDO project. The final goal of the project is to make five demonstrators that show the feasibility of the proposed concepts to make optical interconnects and packet-switched optical networks that are scalable to Pb/s systems in data centers and high performance computing. Simplest transceivers are to be made by combining directly modulated InP VCSELs with 12 μm SOI multiplexers to launch, for example, 200 Gbps data into a single polymer waveguide with 4 channels to connect processors on a single line card. For more advanced transceivers we develop novel dilute nitride amplifiers and modulators that are expected to be more power-efficient and temperatureinsensitive than InP devices. These edge-emitting III-V chips are flip-chip bonded on 3 μm SOI chips that also have polarization and temperature independent multiplexers and low-loss coupling to the 12 μm SOI interposers, enabling to launch up to 640 Gbps data into a standard single mode (SM) fiber. In this paper we present a number of experimental results, including low-loss multiplexers on SOI, zero-birefringence Si waveguides, micron-scale mirrors and bends with 0.1 dB loss, direct modulation of VCSELs up to 40 Gbps, +/-0.25μm length control for dilute nitride SOA, strong band edge shifts in dilute nitride EAMs and SM polymer waveguides with 0.4 dB/cm loss.

  11. Investigation of the design parameters of quantum dot enhanced III-V solar cells

    NASA Astrophysics Data System (ADS)

    Driscoll, Kristina; Bennett, Mitchell; Polly, Stephen; Forbes, David V.; Hubbard, Seth M.

    2013-03-01

    The incorporation of nanostructures, such as quantum dots (QD), into the intrinsic region of III-V solar cells has been proposed as a potential route towards boosting conversion efficiencies with immediate applications in concentrator photovoltaic and space power systems. Necessary to the optimization process of this particular class of solar cells is the ability to correlate nanoscale properties with macroscopic device characteristics. To this purpose, the physics-based software Crosslight APSYS has been developed to investigate the design parameters of QD enhanced solar cells with particular focus on the InAs/GaAs system. This methodology is used to study how nanoscale variables, including size, shape and material compositions, influence photovoltaic performance. In addition, device-level engineering of the nanostructures is explored in optimizing the overall device response. Specifically, the effect of the position of the QDs within the intrinsic regions is investigated. Preliminary simulations suggest strategically placing the QDs off-center reduces non-radiative recombination and thereby the dark saturation current, contributing to a marked increase in opencircuit voltage and fill factor. The short-circuit current remains unchanged in the high field region resulting in an increase in overall conversion efficiency. To further explore this finding, a series of three samples with the QDs placed in the center and near the doped regions of a pin-GaAs solar cell have been grown using MOCVD, fabricated and fully characterized. Contrary to predictions, the emitter-shifted devices exhibit a marked decrease in open-circuit voltage and fill factor. This behavior is attributed to non-negligible n-type background doping in the intrinsic region which shifts the region of maximum recombination towards the p-type emitter.

  12. Protective capping and surface passivation of III-V nanowires by atomic layer deposition

    SciTech Connect

    Dhaka, Veer Perros, Alexander; Kakko, Joona-Pekko; Haggren, Tuomas; Lipsanen, Harri; Naureen, Shagufta; Shahid, Naeem; Jiang, Hua; Kauppinen, Esko; Srinivasan, Anand

    2016-01-15

    Low temperature (∼200 °C) grown atomic layer deposition (ALD) films of AlN, TiN, Al{sub 2}O{sub 3}, GaN, and TiO{sub 2} were tested for protective capping and surface passivation of bottom-up grown III-V (GaAs and InP) nanowires (NWs), and top-down fabricated InP nanopillars. For as-grown GaAs NWs, only the AlN material passivated the GaAs surface as measured by photoluminescence (PL) at low temperatures (15K), and the best passivation was achieved with a few monolayer thick (2Å) film. For InP NWs, the best passivation (∼2x enhancement in room-temperature PL) was achieved with a capping of 2nm thick Al{sub 2}O{sub 3}. All other ALD capping layers resulted in a de-passivation effect and possible damage to the InP surface. Top-down fabricated InP nanopillars show similar passivation effects as InP NWs. In particular, capping with a 2 nm thick Al{sub 2}O{sub 3} layer increased the carrier decay time from 251 ps (as-etched nanopillars) to about 525 ps. Tests after six months ageing reveal that the capped nanostructures retain their optical properties. Overall, capping of GaAs and InP NWs with high-k dielectrics AlN and Al{sub 2}O{sub 3} provides moderate surface passivation as well as long term protection from oxidation and environmental attack.

  13. A novel surface preparation methodology for epi-ready antimonide based III-V substrates

    NASA Astrophysics Data System (ADS)

    Dutta, P. S.; Rajagopalan, G.; Kim, H. J.; Kumar, A.

    2005-05-01

    Surfaces of GaSb substrates currently available from various commercial vendors are nowhere close to device grade GaAs, Si or InP wafer surfaces. Hence epitaxial growth and device fabrication on as-received commercial substrates poses significant difficulties amongst antimonide based researchers. Antimonide based materials are known to have poor surface oxide quality and not so well understood chemical reactions with various chemicals used to remove the oxides prior to growth. There are no existing reports on the detailed recipe for the preparation of "atomically flat and clean" surfaces that works on wafers obtained from various commercial vendors. This paper presents a detailed recipe for obtaining atomically flat and clean GaSb surfaces, irrespective of the initial polishing source. The same recipe (with slight modification) has been found to be successful with other III-V and II-VI compounds. The novel surface preparation process developed in our laboratory includes, chemical-mechanical polishing using an agglomerate-free sub-micron alumina slurry on a soft pad such as velvet, surface cleaning using dilute ammonium or potassium hydroxide-H2O solution and surfactant or glycerol, surface degreasing using organic solvents, oxide desorption using HCl-H2O and HF-H2O mixtures, mild chemical etching using ammonium sulfide and a final rinse in high purity deionized (DI) water and methanol. Using this recipe, we have been able to achieve surfaces with atomic flatness (RMS surface roughness close to 0.5 nm over a 10 x 10 mm2) and extremely clean surfaces, irrespective of the initial contamination or the sources of the wafers. Results of wafer surfaces before and after polishing using our recipe will be presented.

  14. Semiconductor quantum well lasers and related optoelectronic devices on silicon, III-V

    NASA Astrophysics Data System (ADS)

    Holonyak, N., Jr.; Hsieh, K. C.; Stillman, G. E.

    1989-06-01

    Although an ultimate goal of this work is to achieve long term reliable laser operation of Al(x)Ga(1-x)As-GaAs quantum well heterostructures (QWH's), or similar III-V QWH's, grown on Si, this has proven to be a formidable enough problem that to the best of our knowledge no one has exceeded the results we reported in 1987 and 1988. This problem is of such dimensions that it may not be solved for as much as 10 years, or even more. All we know so far is that continuous (CW) 300 K Al(x)Ga(1-x)As-GaAs QWH lasers can be grown on Si, and that, indeed, the heat sinking of an Al(x)Ga(1-x)As-GaAs QWH laser on Si is better than a similar laser on a GaAs substrate. Nevertheless, the problem of growing better versions of these devices (i.e., long-lived high performance CW 300 K lasers on Si) has run into the fundamental issue of the large GaAs-Si lattice and thermal expansion mismatch, and hence the built-in difficulty in reducing the defects guaranteed by mismatch. Accordingly, and as much as we have worked further on the problem of Al(x)Ga(1-x)As-GaAs QWH lasers on Si, we have worked as hard on other QWH laser problems, as well as a impurity-induced layer disordering (or layer intermixing, IILD) and its application in laser devices. We briefly describe this work below and append the titles and abstracts of the papers we have published on laser studies and IILD.

  15. Nanometer-Scale Compositional Structure in III-V Semiconductor Heterostructures Characterized by Scanning Tunneling Microscopy

    SciTech Connect

    Allerman, A.A.; Bi, W.G.; Biefeld, R.M.; Tu, C.W.; Yu, E.T.; Zuo, S.L.

    1998-11-10

    Nanometer-scale compositional structure in InAsxP1.InNYAsxPl.x-Y/InP, grown by gas-source molecular-beam epitaxy and in InAsl-xPJkAsl$b#InAs heterostructures heterostructures grown by metal-organic chemical vapor deposition has been characterized using cross-sectional scanning tunneling microscopy. InAsxP1-x alloy layers are found to contain As-rich and P-rich clusters with boundaries formed preferentially within (T 11) and (111) crystal planes. Similar compositional structure is observed within InNYAsxP1-x-Y alloy layers. Imaging of InAsl-xp@Asl#bY superlattices reveals nanometer-scale clustering within both the hAsI-.p and InAsl$bY alloy layers, with preferential alignment of compositional features in the direction. Instances are observed of compositional structure correlated across a heterojunction interface, with regions whose composition corresponds to a smaller unstrained lattice, constant relative to the surrounding alloy material appearing to propagate across the interface.

  16. International Workshop on Hydrogen Passivation of Dopants and Defects in III-V Compounds and Their Alloys

    DTIC Science & Technology

    1988-11-04

    operation. Present addreR: Raytheon 3esearch, 131 Spring Sreet. Lexington, MA 02173 ACTIVITIE 0[:IYzEOG:N -AS’’AIN rEECS -rLI Gerhard Pensl institute cf...continued support. References [1] J. Tatarkiewicz, M. Stutzmann, phys. stat. sol, (b) 149, no. 2 (1988), in press; [21 G. Herzberg "Molecular Spectra and

  17. Ga-rich GaxIn1-xP solar cells on Si with 1.95 eV bandgap for ideal III-V/Si photovoltaics

    NASA Astrophysics Data System (ADS)

    Ratcliff, Christopher; Grassman, T. J.; Carlin, J. A.; Chmielewski, D. J.; Ringel, S. A.

    2014-03-01

    Theoretical models for III-V compound multijunction solar cells show that solar cells with bandgaps of 1.95-2.3 eV are needed to create ideal optical partitioning of the solar spectrum for device architectures containing three, four and more junctions. For III-V solar cells integrated with an active Si sub-cell, GaInP alloys in the Ga-rich regime are ideal since direct bandgaps of up to ~ 2.25 eV are achieved at lattice constants that can be integrated with appropriate GaAsP, SiGe and Si materials, with efficiencies of almost 50% being predicted using practical solar cell models under concentrated sunlight. Here we report on Ga-rich, lattice-mismatched Ga0.57In0.43P sub-cell prototypes with a bandgap of 1.95 eV grown on tensile step-graded metamorphic GaAsyP1-y buffers on GaAs substrates. The goal is to create a high bandgap top cell for integration with Si-based III-V/Si triple-junction devices. Excellent carrier collection efficiency was measured via internal quantum efficiency measurements and with their design being targeted for multijunction implementation (i.e. they are too thin for single junction cells), initial cell results are encouraging. The first generation of identical 1.95 eV cells on Si were fabricated as well, with efficiencies for these large bandgap, thin single junction cells ranging from 7% on Si to 11% on GaAs without antireflection coatings, systematically tracking the change in defect density as a function of growth substrate.

  18. Mono- and polynucleation, atomistic growth, and crystal phase of III-V nanowires under varying group V flow

    SciTech Connect

    Dubrovskii, V. G.

    2015-05-28

    We present a refined model for the vapor-liquid-solid growth and crystal structure of Au-catalyzed III-V nanowires, which revisits several assumptions used so far and is capable of describing the transition from mononuclear to polynuclear regime and ultimately to regular atomistic growth. We construct the crystal phase diagrams and calculate the wurtzite percentages, elongation rates, critical sizes, and polynucleation thresholds of Au-catalyzed GaAs nanowires depending on the As flow. We find a non-monotonic dependence of the crystal phase on the group V flow, with the zincblende structure being preferred at low and high group V flows and the wurtzite structure forming at intermediate group V flows. This correlates with most of the available experimental data. Finally, we discuss the atomistic growth picture which yields zincblende crystal structure and should be very advantageous for fabrication of ternary III-V nanowires with well-controlled composition and heterointerfaces.

  19. Growth and Defect Characterization of Quantum Dot-Embedded III-V Semiconductors for Advanced Space Photovoltaics

    DTIC Science & Technology

    2014-05-15

    provide, which could be useful in the future development of intermediate band solar cell (IBSC) devices. Defect spectroscopy was also performed on OMVPE...grown InAs/GaAs QD-embedded solar cells . A large increase in mid-gap trap density surrounding the embedded QDs was found and points to a potentially... cell calibration, high altitude solar cell calibration, high altitude balloon solar cell calibration, III-V compound semiconductors, solar cells

  20. 'Junction-Level' Heterogeneous Integration of III-V Materials with Si CMOS for Novel Asymmetric Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Chang, Yoon Jung

    Driven by Moore's law, semiconductor chips have become faster, denser and cheaper through aggressive dimension scaling. The continued scaling not only led to dramatic performance improvements in digital logic applications but also in mixed-mode and/or communication applications. Moreover, size/weight/power (SWAP) restrictions on all high-performance system components have resulted in multi-functional integration of multiple integrated circuits (ICs)/dies in 3D packages/ICs by various system-level approaches. However, these approaches still possess shortcomings and in order to truly benefit from the most advanced digital technologies, the future high-speed/high power devices for communication applications need to be fully integrated into a single CMOS chip. Due to limitations in Si device performance in high-frequency/power applications as well as expensive III-V compound semiconductor devices with low integration density, heterogeneous integration of compound semiconductor materials/devices with Si CMOS platform has emerged as a viable solution to low-cost high-performance ICs. In this study, we first discuss on channel and drain engineering approaches in the state-of-the-art multiple-gate field-effect transistor to integrate III-V compound semiconductor materials with Si CMOS for improved device performance in mixed-mode and/or communication applications. Then, growth, characterization and electrical analysis on small-area (diameter < 100nm) complete selective-area epitaxy of GaAs/GaN will be demonstrated for achieving 'dislocation-free' III-V compound semiconductor film on a Si(001) substrate. Based on a success in dislocation-free heterogeneous III-V film growth, we propose a novel ultra-scaled 'junction-level' heterogeneous integration onto mainstream Si CMOS platform. Device architecture and its key features to overcome aforementioned challenges will be given to demonstrate the potential to improve the overall system performance with diverse functionality.

  1. All-optical NRZ wavelength conversion based on a single hybrid III-V/Si SOA and optical filtering.

    PubMed

    Wu, Yingchen; Huang, Qiangsheng; Keyvaninia, Shahram; Katumba, Andrew; Zhang, Jing; Xie, Weiqiang; Morthier, Geert; He, Jian-Jun; Roelkens, Gunther

    2016-09-05

    We demonstrate all-optical wavelength conversion (AOWC) of non-return-to-zero (NRZ) signal based on cross-gain modulation in a single heterogeneously integrated III-V-on-silicon semiconductor optical amplifier (SOA) with an optical bandpass filter. The SOA is 500 μm long and consumes less than 250 mW electrical power. We experimentally demonstrate 12.5 Gb/s and 40 Gb/s AOWC for both wavelength up and down conversion.

  2. Electronic band structure and material gain of III-V-Bi quantum wells grown on GaSb substrate and dedicated for mid-infrared spectral range

    NASA Astrophysics Data System (ADS)

    Gladysiewicz, M.; Kudrawiec, R.; Wartak, M. S.

    2016-02-01

    The 8-band kp Hamiltonian is applied to calculate electronic band structure and material gain in III-V-Bi quantum wells (QWs) grown on GaSb substrates. We analyzed three Bi-containing QWs (GaSbBi, GaInSbBi, and GaInAsSbBi) and different Bi-free barriers (GaSb and AlGaInAsSb), lattice matched to GaSb. Bi-related changes in the electronic band structure of III-V host incorporated into our formalism are based on recent ab-initio calculations for ternary alloys (III-Ga-Bi and III-In-Bi) [Polak et al., Semicond. Sci. Technol. 30, 094001 (2015)]. When compared to Bi-free QWs, the analyzed Bi-containing structures show much better quantum confinement in the valence band and also larger redshift of material gain peak per percent of compressive strain. For 8 nm thick GaInSb/GaSb QWs, material gain of the transverse electric (TE) mode is predicted at 2.1 μm for the compressive strain of ɛ = 2% (32% In). The gain peak of the TE mode in 8 nm thick GaSbBi/GaSb QW reaches this wavelength for compressive strain of 0.15% that corresponds to about 5% Bi. It has also been shown that replacing In atoms by Bi atoms in GaInSbBi/GaSb QWs while keeping the same compressive strain (ɛ = 2%) in QW region enhances and shifts gain peak significantly to the longer wavelengths. For 8 nm wide GaInSbBi/GaSb QW with 5% Bi, the gain peak is predicted at around 2.6 μm, i.e., is redshifted by about 400 nm compared to Bi-free QW. For 8 nm wide GaInAsSbSb QWs (80% In, 5% Bi, and ɛ = 2%) with proper AlGaInAsSb barriers, it is possible to achieve large material gain even at 4.0 μm.

  3. Toward the III-V/Si co-integration by controlling the biatomic steps on hydrogenated Si(001)

    NASA Astrophysics Data System (ADS)

    Martin, M.; Caliste, D.; Cipro, R.; Alcotte, R.; Moeyaert, J.; David, S.; Bassani, F.; Cerba, T.; Bogumilowicz, Y.; Sanchez, E.; Ye, Z.; Bao, X. Y.; Pin, J. B.; Baron, T.; Pochet, P.

    2016-12-01

    The integration of III-V on silicon is still a hot topic as it will open up a way to co-integrate Si CMOS logic with photonic devices. To reach this aim, several hurdles should be solved, and more particularly the generation of antiphase boundaries (APBs) at the III-V/Si(001) interface. Density functional theory (DFT) has been used to demonstrate the existence of a double-layer steps on nominal Si(001) which is formed during annealing under proper hydrogen chemical potential. This phenomenon could be explained by the formation of dimer vacancy lines which could be responsible for the preferential and selective etching of one type of step leading to the double step surface creation. To check this hypothesis, different experiments have been carried in an industrial 300 mm metalorganic chemical vapor deposition where the total pressure during the annealing step of Si(001) surface has been varied. Under optimized conditions, an APBs-free GaAs layer was grown on a nominal Si(001) surface paving the way for III-V integration on silicon industrial platform.

  4. Second-order optical susceptibility in doped III-V piezoelectric semiconductors in the presence of a magnetostatic field

    NASA Astrophysics Data System (ADS)

    Lal, B.; Aghamkar, P.; Kumar, S.; Kashyap, M. K.

    2011-02-01

    A detailed analytical investigation of second-order optical susceptibility has been made in moderately doped III-V weakly piezoelectric semiconductor crystal, viz. n-InSb, in the absence and presence of an external magnetostatic field, using the coupled mode theory. The second-order optical susceptibility arises from the nonlinear interaction of a pump beam with internally generated density and acoustic perturbations. The effect of doping concentration, magnetostatic field and pump intensity on second-order optical susceptibility of III-V semiconductors has been studied in detail. The numerical estimates are made for n-type InSb crystals duly shined by pulsed 10.6 μm CO2 laser and efforts are made towards optimising the doping level, applied magnetostatic field and pump intensity to achieve a large value of second-order optical susceptibility and change of its sign. The enhancement in magnitude and change of sign of second-order optical susceptibility, in weakly piezoelectric III-V semiconductor under proper selection of doping concentration and externally applied magnetostatic field, confirms the chosen nonlinear medium as a potential candidate material for the fabrication of nonlinear optical devices. In particular, at B 0 = 14.1 T, the second-order susceptibility was found to be 3.4 × 10-7 (SI unit) near the resonance condition.

  5. Silicon, germanium, and III-V-based tunneling devices for low-power applications

    NASA Astrophysics Data System (ADS)

    Smith, Joshua T.

    While the scaling of transistor dimensions has kept pace with Moore's Law, the voltages applied to these devices have not scaled in tandem, giving rise to ever-increasing power/heating challenges in state-of-the-art integrated circuits. A primary reason for this scaling mismatch is due to the thermal limit---the 60 mV minimum required at room temperature to change the current through the device by one order of magnitude. This voltage scaling limitation is inherent in devices that rely on the mechanism of thermal emission of charge carriers over a gate-controlled barrier to transition between the ON- and OFF-states, such as in the case of conventional CMOS-based technologies. To overcome this voltage scaling barrier, several steep-slope device concepts have been pursued that have experimentally demonstrated sub-60-mV/decade operation since 2004, including the tunneling-field effect transistor (TFET), impact ionization metal-oxide-semiconductor (IMOS), suspended-gate FET (SG-FET), and ferroelectric FET (Fe-FET). These reports have excited strong efforts within the semiconductor research community toward the realization of a low-power device that will support continued scaling efforts, while alleviating the heating issues prevalent in modern computer chips. Literature is replete with claims of sub-60-mV/decade operation, but often with neglect to other voltage scaling factors that offset this result. Ideally, a low-power device should be able to attain sub-60-mV/decade inverse subthreshold slopes (S) employing low supply and gate voltages with a foreseeable path toward integration. This dissertation describes the experimental development and realization of CMOS-compatible processes to enhance tunneling efficiency in Si and Si/Ge nanowire (NW) TFETs for improved average S (S avg) and ON-currents (ION), and a novel, III-V-based tunneling device alternative is also proposed. After reviewing reported efforts on the TFET, IMOS, and SG-FET, the TFET is highlighted as the

  6. Highly Scaled High Dielectric Constant Oxides on III-V CMOS with Low Interface Trap and Low Leakage Densities

    NASA Astrophysics Data System (ADS)

    Chobpattana, Varistha

    Complementary metal-oxide-semiconductor (CMOS) transistors are being aggressively scaled, reaching the fundamental limits of silicon. Due to their much higher electron mobilities, III-V semiconductors are being considered as alternative channel materials to potentially replace Si. This requires the integration of high dielectric constant (high-k) oxides with III-V semiconductor layers, which is the most significant challenge to achieve high performance of III-V metal-oxide-semiconductor field-effect transistors (MOSFETs). Large interface trap densities, inherent to these interfaces, degrade the transistor performance. In this dissertation, we utilize in-situ atomic layer deposition (ALD) combined with surface passivation techniques to reduce the interface traps densities between high-k oxides and III-V semiconductors to obtain highly scaled, low defect density interfaces. Cycles of hydrogen and/or nitrogen plasmas and metal-organic precursors were applied directly onto n- and p type In0.53 Ga0.47As surfaces before high-k oxide ALD. The high-k oxides investigated include Al2O 3, HfO2, ZrO2, and TiO2. We examined the electrical characteristics of MOS capacitors (MOSCAPs), surface morphology of the surface, and chemical components of the interface. High quality interfaces of high-k oxide and n-type In0.53Ga0.47As with low interface trap densities (Dit) of 1012 eV-1 cm-2, low leakage current density, and high capacitance densities gate stacks (>5 muF/cm 2) were achieved by the optimized cycles of nitrogen plasma+tetrakis(dimethylamido)titanium (TDMAT) ALD surface cleaning. Using x-ray photoelectron spectroscopy, the interface region indicates that the removing As-oxides, sub-oxides, and As-As bonding are responsible for decreasing frequency dispersion in the midgap region of the n-type In0:53Ga0:47As, reducing midgap Dit, and unpinning Fermi level. The modified interface chemistry from Al2O3 to TiO2 leads to lower frequency dispersion in accumulation. The highly

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

    NASA Astrophysics Data System (ADS)

    Choi, Donghun

    Integration of III-V compound semiconductors on silicon substrates has recently received much attention for the development of optoelectronic and high speed electronic devices. However, it is well known that there are some key challenges for the realization of III-V device fabrication on Si substrates: (i) the large lattice mismatch (in case of GaAs: 4.1%), and (ii) the formation of antiphase domain (APD) due to the polar compound semiconductor growth on non-polar elemental structure. Besides these growth issues, the lack of a useful surface passivation technology for compound semiconductors has precluded development of metal-oxide-semiconductor (MOS) devices and causes high surface recombination parasitics in scaled devices. This work demonstrates the growth of high quality III-V materials on Si via an intermediate Ge buffer layer and some surface passivation methods to reduce interface defect density for the fabrication of MOS devices. The initial goal was to achieve both low threading dislocation density (TDD) and low surface roughness on Ge-on-Si heterostructure growth. This was achieved by repeating a deposition-annealing cycle consisting of low temperature deposition + high temperature-high rate deposition + high temperature hydrogen annealing, using reduced-pressure chemical-vapor deposition (CVD). We then grew III-V materials on the Ge/Si virtual substrates using molecular-beam epitaxy (MBE). The relationship between initial Ge surface configuration and antiphase boundary formation was investigated using surface reflection high-energy electron diffraction (RHEED) patterns and atomic force microscopy (AFM) image analysis. In addition, some MBE growth techniques, such as migration enhanced epitaxy (MEE) and low temperature GaAs growth, were adopted to improve surface roughness and solve the Ge self-doping problem. Finally, an Al2O3 gate oxide layer was deposited using atomic-layer-deposition (ALD) system after HCl native oxide etching and ALD in-situ pre

  8. Threading dislocation reduction in III-V films: Theoretical modeling and experimental methods

    NASA Astrophysics Data System (ADS)

    Mathis, Sheila Kathleen

    Heteroepitaxy remains the most efficient and successful way to integrate materials with the same crystal structure but different lattice constants and optoelectronic properties. The purpose of this work is to understand the processes of strain relaxation and subsequent threading dislocation (TD) reduction through modeling and experiment. The interpretation of these data is made according to a previously published model that is based on dislocation reactions. 1,2 These reactions are the sole mechanism for threading dislocation reduction in III--V epitaxial films.3 Gallium nitride, with no available substrate even close to the lattice-matched condition, has a unique microstructure that develops as a result of initial island growth. Dislocation densities on the order of 109--10 10/cm2 are routinely measured in GaN grown on sapphire. Dislocation reduction in these hexagonal films is extremely slow, and it is shown in Chapter II that film thicknesses on the order of a substrate thickness are required to reduce threading dislocation densities to a low (10 6/cm2) level. A model is developed to treat the reduction of TDs in (0001)-oriented films that explains the non-saturating TD density in GaN. Screw dislocation behavior is shown to strongly affect the dislocation density falloff with thickness. Threading dislocation reduction in low-temperature-grown GaAs (250--350°C) and InGaAs was known to be more efficient than in high-temperature-grown GaAs (580°C). Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to study the microstructure of GaAs grown on InP substrates at temperatures between 250 and 580°C to determine the mechanism by which TD reduction was enhanced. While a high level of arsenic antisite defects [ASGa] may affect the TD density at temperatures below 300°C, they do not account for the improved dislocation reduction. When dislocations are generated at high temperature, the TD density on the (111)A and (111)B planes is asymmetric

  9. Metabolomic and proteomic biomarkers for III-V semiconductors: chemical-specific porphyrinurias and proteinurias.

    PubMed

    Fowler, Bruce A; Conner, Elizabeth A; Yamauchi, Hiroshi

    2005-08-07

    A pressing need exists to develop and validate molecular biomarkers to assess the early effects of chemical agents, both individually and in mixtures. This is particularly true for new and chemically intensive industries such as the semiconductor industry. Previous studies from this laboratory and others have demonstrated element-specific alterations of the heme biosynthetic pathway for the III-V semiconductors gallium arsenide (GaAs) and indium arsenide (InAs) with attendant increased urinary excretion of specific heme precursors. These data represent an example of a metabolomic biomarker to assess chemical effects early, before clinical disease develops. Previous studies have demonstrated that the intratracheal or subcutaneous administration of GaAs and InAs particles to hamsters produces the induction of the major stress protein gene families in renal proximal tubule cells. This was monitored by 35-S methionine labeling of gene products followed by two-dimensional gel electrophoresis after exposure to InAs particles. The present studies examined whether these effects were associated with the development of compound-specific proteinuria after 10 or 30 days following subcutaneous injection of GaAs or InAs particles in hamsters. The results of these studies demonstrated the development of GaAs- and InAs-specific alterations in renal tubule cell protein expression patterns that varied at 10 and 30 days. At the 30-day point, cells in hamsters that received InAs particles showed marked attenuation of protein expression, suggesting inhibition of the stress protein response. These changes were associated with GaAs and InAs proteinuria patterns as monitored by two-dimensional gel electrophoresis and silver staining. The intensity of the protein excretion patterns increased between the 10- and 30-day points and was most pronounced for animals in the 30-day InAs treatment group. No overt morphologic signs of cell death were seen in renal tubule cells of these animals

  10. Metabolomic and proteomic biomarkers for III-V semiconductors: Chemical-specific porphyrinurias and proteinurias

    SciTech Connect

    Fowler, Bruce A. . E-mail: bxf9@cdc.gov; Conner, Elizabeth A.; Yamauchi, Hiroshi

    2005-08-07

    A pressing need exists to develop and validate molecular biomarkers to assess the early effects of chemical agents, both individually and in mixtures. This is particularly true for new and chemically intensive industries such as the semiconductor industry. Previous studies from this laboratory and others have demonstrated element-specific alterations of the heme biosynthetic pathway for the III-V semiconductors gallium arsenide (GaAs) and indium arsenide (InAs) with attendant increased urinary excretion of specific heme precursors. These data represent an example of a metabolomic biomarker to assess chemical effects early, before clinical disease develops. Previous studies have demonstrated that the intratracheal or subcutaneous administration of GaAs and InAs particles to hamsters produces the induction of the major stress protein gene families in renal proximal tubule cells. This was monitored by 35-S methionine labeling of gene products followed by two-dimensional gel electrophoresis after exposure to InAs particles. The present studies examined whether these effects were associated with the development of compound-specific proteinuria after 10 or 30 days following subcutaneous injection of GaAs or InAs particles in hamsters. The results of these studies demonstrated the development of GaAs- and InAs-specific alterations in renal tubule cell protein expression patterns that varied at 10 and 30 days. At the 30-day point, cells in hamsters that received InAs particles showed marked attenuation of protein expression, suggesting inhibition of the stress protein response. These changes were associated with GaAs and InAs proteinuria patterns as monitored by two-dimensional gel electrophoresis and silver staining. The intensity of the protein excretion patterns increased between the 10- and 30-day points and was most pronounced for animals in the 30-day InAs treatment group. No overt morphologic signs of cell death were seen in renal tubule cells of these animals

  11. Strained InGaAs/InAlAs Quantum Wells for Complementary III-V Transistors

    DTIC Science & Technology

    2014-01-01

    InAlAs. Integrated circuits based on InP HEMTs are suitable for a variety of microwave applications including cell phones, cellular base stations, fiber...barrier p-FETs with good DC and microwave performance [12,18]. In addition, (In)GaSb-channel MOSFETs have been fabri- cated; they have the attractive...shutters and the As and Sb valves remained open , allowing better control of composition compared to random alloys [13,34,35]. Short-period superlattices

  12. Optimized III-V Multijunction Concentrator Solar Cells on Patterned Si and Ge Substrates: Final Technical Report, 15 September 2004--30 September 2006

    SciTech Connect

    Ringel, S. A.

    2008-11-01

    Goal is to demo realistic path to III-V multijunction concentrator efficiencies > 40% by substrate-engineering combining compositional grading with patterned epitaxy for small-area cells for high concentration.

  13. Synthesis and Characterization of Mixed III-V and II-VI Semiconductor Monomers Included in the Borate Sodalite Analogue

    DTIC Science & Technology

    1993-04-30

    Characterization of Mixed III-V and .I-VI N00014-k0-J-er59Semiconductor Monomrers Included in the Borate Sodalite Analogue ..... C LL AU N.𔃾 K.L. Moran...dependent static and magic angle spinning and solid state NMR experiments. Inclusion of GaP within the borate sodalite analogue results in the formation of an...properties of compounds can be dramatically altered by inclusion into the sodalite framework, which is one of several reasons why this zeolite structure

  14. Specific Approach for Size-Control III-V Quantum/Nano LED Fabrication for Prospective White Light Source

    DTIC Science & Technology

    2007-08-10

    The Final Report Title: Specific approach for size-control III-V based quantum/nano LED fabrication for prospective white ...COVERED 14-06-2005 to 14-12-2005 4. TITLE AND SUBTITLE Size controlled GaN based quantum dot LED for the prospective white light source 5a. CONTRACT...structure LED The physical model of the PC LED for optical simulation is shown in Figure 10. The LED are composed with p-type GaN/ MQW of InGaN /GaN/ n

  15. Hybrid III-V on Si grating as a broadband reflector and a high-Q resonator

    NASA Astrophysics Data System (ADS)

    Chung, Il-Sug; Taghizadeh, Alireza; Park, Gyeong Cheol

    2016-03-01

    Hybrid grating (HG) with a high-refractive-index cap layer added onto a high contrast grating (HCG), can provide a high reflectance close 100 % over a broader wavelength range than HCGs, or work as a ultrahigh quality (Q) factor resonator. The reflection and resonance properties of HGs have been investigated and the mechanisms leading to these properties are discussed. A HG reflector sample integrating a III-V cap layer with InGaAlAs quantum wells onto a Si grating has been fabricated and its reflection property has been characterized. The HG-based lasers have a promising prospect for silicon photonics light source or high-speed laser applications.

  16. III-V Ultra-Thin-Body InGaAs/InAs MOSFETs for Low Standby Power Logic Applications

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Ying

    As device scaling continues to sub-10-nm regime, III-V InGaAs/InAs metal- oxide-semiconductor ?eld-e?ect transistors (MOSFETs) are promising candidates for replacing Si-based MOSFETs for future very-large-scale integration (VLSI) logic applications. III-V InGaAs materials have low electron effective mass and high electron velocity, allowing higher on-state current at lower VDD and reducing the switching power consumption. However, III-V InGaAs materials have a narrower band gap and higher permittivity, leading to large band-to-band tunneling (BTBT) leakage or gate-induced drain leakage (GIDL) at the drain end of the channel, and large subthreshold leakage due to worse electrostatic integrity. To utilize III-V MOSFETs in future logic circuits, III-V MOSFETs must have high on-state performance over Si MOSFETs as well as very low leakage current and low standby power consumption. In this dissertation, we will report InGaAs/InAs ultra-thin-body MOSFETs. Three techniques for reducing the leakage currents in InGaAs/InAs MOSFETs are reported as described below. 1) Wide band-gap barriers: We developed AlAs0.44Sb0.56 barriers lattice-match to InP by molecular beam epitaxy (MBE), and studied the electron transport in In0.53Ga0.47As/AlAs 0.44Sb0.56 heterostructures. The InGaAs channel MOSFETs using AlAs0.44Sb0.56 bottom barriers or p-doped In0.52 Al0.48As barriers were demonstrated, showing significant suppression on the back barrier leakage. 2) Ultra-thin channels: We investigated the electron transport in InGaAs and InAs ultra-thin quantum wells and ultra-thin body MOSFETs (t ch ~ 2-4 nm). For high performance logic, InAs channels enable higher on-state current, while for low power logic, InGaAs channels allow lower BTBT leakage current. 3) Source/Drain engineering: We developed raised InGaAs and recessed InP source/drain spacers. The raised InGaAs source/drain spacers improve electrostatics, reducing subthreshold leakage, and smooth the electric field near drain, reducing

  17. III-V-N materials for super high-efficiency multijunction solar cells

    SciTech Connect

    Yamaguchi, Masafumi; Bouzazi, Boussairi; Suzuki, Hidetoshi; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio

    2012-10-06

    We have been studying concentrator multi-junction solar cells under Japanese Innovative Photovoltaic R and D program since FY2008. InGaAsN is one of appropriate materials for 4-or 5-junction solar cell configuration because this material can be lattice-matched to GaAs and Ge substrates. However, present InGaAsN single-junction solar cells have been inefficient because of low minority-carrier lifetime due to N-related recombination centers and low carrier mobility due to alloy scattering and non-homogeneity of N. This paper presents our major results in the understanding of majority and minority carrier traps in GaAsN grown by chemical beam epitaxy and their relationships with the poor electrical properties of the materials.

  18. III-V-N materials for super high-efficiency multijunction solar cells

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Masafumi; Bouzazi, Boussairi; Suzuki, Hidetoshi; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio

    2012-10-01

    We have been studying concentrator multi-junction solar cells under Japanese Innovative Photovoltaic R&D program since FY2008. InGaAsN is one of appropriate materials for 4-or 5-junction solar cell configuration because this material can be lattice-matched to GaAs and Ge substrates. However, present InGaAsN single-junction solar cells have been inefficient because of low minority-carrier lifetime due to N-related recombination centers and low carrier mobility due to alloy scattering and non-homogeneity of N. This paper presents our major results in the understanding of majority and minority carrier traps in GaAsN grown by chemical beam epitaxy and their relationships with the poor electrical properties of the materials.

  19. 30 CFR 57.22222 - Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines). 57.22222 Section 57.22222 Mineral Resources MINE SAFETY AND HEALTH....22222 Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines). Brattice cloth...

  20. 30 CFR 57.22222 - Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines). 57.22222 Section 57.22222 Mineral Resources MINE SAFETY AND HEALTH....22222 Ventilation materials (I-A, I-B, I-C, II-A, III, V-A, and V-B mines). Brattice cloth...

  1. High-coherence semiconductor lasers based on integral high-Q resonators in hybrid Si/III-V platforms.

    PubMed

    Santis, Christos Theodoros; Steger, Scott T; Vilenchik, Yaakov; Vasilyev, Arseny; Yariv, Amnon

    2014-02-25

    The semiconductor laser (SCL) is the principal light source powering the worldwide optical fiber network. The ever-increasing demand for data is causing the network to migrate to phase-coherent modulation formats, which place strict requirements on the temporal coherence of the light source that no longer can be met by current SCLs. This failure can be traced directly to the canonical laser design, in which photons are both generated and stored in the same, optically lossy, III-V material. This leads to an excessive and large amount of noisy spontaneous emission commingling with the laser mode, thereby degrading its coherence. High losses also decrease the amount of stored optical energy in the laser cavity, magnifying the effect of each individual spontaneous emission event on the phase of the laser field. Here, we propose a new design paradigm for the SCL. The keys to this paradigm are the deliberate removal of stored optical energy from the lossy III-V material by concentrating it in a passive, low-loss material and the incorporation of a very high-Q resonator as an integral (i.e., not externally coupled) part of the laser cavity. We demonstrate an SCL with a spectral linewidth of 18 kHz in the telecom band around 1.55 μm, achieved using a single-mode silicon resonator with Q of 10(6).

  2. Electronic Band Structures of the Highly Desirable III-V Semiconductors: TB-mBJ DFT Studies

    NASA Astrophysics Data System (ADS)

    Rehman, Gul; Shafiq, M.; Saifullah; Ahmad, Rashid; Jalali-Asadabadi, S.; Maqbool, M.; Khan, Imad; Rahnamaye-Aliabad, H.; Ahmad, Iftikhar

    2016-07-01

    The correct band gaps of semiconductors are highly desirable for their effective use in optoelectronic and other photonic devices. However, the experimental and theoretical results of the exact band gaps are quite challenging and sometimes tricky. In this article, we explore the electronic band structures of the highly desirable optical materials, III-V semiconductors. The main reason of the ineffectiveness of the theoretical band gaps of these compounds is their mixed bonding character, where large proportions of electrons reside outside atomic spheres in the intestinal regions, which are challenging for proper theoretical treatment. In this article, the band gaps of the compounds are revisited and successfully reproduced by properly treating the density of electrons using the recently developed non-regular Tran and Blaha's modified Becke-Johnson (nTB-mBJ) approach. This study additionally suggests that this theoretical scheme could also be useful for the band gap engineering of the III-V semiconductors. Furthermore, the optical properties of these compounds are also calculated and compared with the experimental results.

  3. Fully first-principles sX-LDA calculations of excited states and optical properties of III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Hyon Rhim, Sung; Kim, Miyoung; Freeman, A. J.

    2004-03-01

    III-V semiconductors are important for their extensive applications as optical devices such as laser diodes and infrared sensors. Optical properties, [ɛ_2(ω), n, k, R, and α], of III-V semiconductors (InAs, InSb, GaSb, and AlSb), are investigated using our highly precise full-potential linearized augmented plane wave(E.Wimmer,H.Krakauer, M.Weinert, A.J.Freeman, PRB,24), 864 (1981)(FLAPW) method with the screened-exchange local density approximation( R.Asahi,W.Mannstadt, A.J.Freeman,PRB,59), 7486 (1999)(sX-LDA) solved self-consistently and with spin-orbit coupling included. The imaginary part of the dielectric constant, ɛ_2(ω) is calculated using the longitudinal expression with full e^iqotr matrix elements, due to the nonlocality of the potential in the sX-LDA method(R.Del Sole, R.Girlanda, PRB 48), 11789 (1993). The structure of the ɛ_2(ω)'s are analyzed with band structures and consideration of interband transitions. The result shows good agreement of the peak positions in ɛ_2(ω) with experiment( D.E.Aspnes,A.A.Studna, PRB 27), 985 (1983) .

  4. DX centers in III-V semiconductors under hydrostatic pressure. [GaAs:Si; InP:S

    SciTech Connect

    Wolk, J.A.

    1992-11-01

    DX centers are deep level defects found in some III-V semiconductors. They have persistent photoconductivity and large difference between thermal and optical ionization energies. Hydrostatic pressure was used to study microstructure of these defects. A new local vibrational mode (LVM) was observed in hydrostatically stressed, Si-doped GaAs. Corresponding infrared absorption peak is distinct from the Si[sub Ga] shallow donor LVM peak, which is the only other LVM peak observed in our samples, and is assigned to the Si DX center. Analysis of the relative intensities of the Si DX LVM and the Si shallow donor LVM peaks, combined with Hall effect and resistivity indicate that the Si DX center is negatively charged. Frequency of this new mode provides clues to the structure of this defect. A pressure induced deep donor level in S-doped InP was also discovered which has the properties of a DX center. Pressure at which the new defect becomes more stable than the shallow donor is 82 kbar. Optical ionization energy and energy dependence of the optical absorption cross section was measured for this new effect. Capture barrier from the conduction band into the DX state were also determined. That DX centers can be formed in InP by pressure suggests that DX states should be common in n-type III-V semiconductors. A method is suggested for predicting under what conditions these defects will be the most stable form of the donor impurity.

  5. A direct thin-film path towards low-cost large-area III-V photovoltaics.

    PubMed

    Kapadia, Rehan; Yu, Zhibin; Wang, Hsin-Hua H; Zheng, Maxwell; Battaglia, Corsin; Hettick, Mark; Kiriya, Daisuke; Takei, Kuniharu; Lobaccaro, Peter; Beeman, Jeffrey W; Ager, Joel W; Maboudian, Roya; Chrzan, Daryl C; Javey, Ali

    2013-01-01

    III-V photovoltaics (PVs) have demonstrated the highest power conversion efficiencies for both single- and multi-junction cells. However, expensive epitaxial growth substrates, low precursor utilization rates, long growth times, and large equipment investments restrict applications to concentrated and space photovoltaics (PVs). Here, we demonstrate the first vapor-liquid-solid (VLS) growth of high-quality III-V thin-films on metal foils as a promising platform for large-area terrestrial PVs overcoming the above obstacles. We demonstrate 1-3 μm thick InP thin-films on Mo foils with ultra-large grain size up to 100 μm, which is ~100 times larger than those obtained by conventional growth processes. The films exhibit electron mobilities as high as 500 cm²/V-s and minority carrier lifetimes as long as 2.5 ns. Furthermore, under 1-sun equivalent illumination, photoluminescence efficiency measurements indicate that an open circuit voltage of up to 930 mV can be achieved, only 40 mV lower than measured on a single crystal reference wafer.

  6. Analysis of the Si(111) surface prepared in chemical vapor ambient for subsequent III-V heteroepitaxy

    NASA Astrophysics Data System (ADS)

    Zhao, W.; Steidl, M.; Paszuk, A.; Brückner, S.; Dobrich, A.; Supplie, O.; Kleinschmidt, P.; Hannappel, T.

    2017-01-01

    For well-defined heteroepitaxial growth of III-V epilayers on Si(111) substrates the atomic structure of the silicon surface is an essential element. Here, we study the preparation of the Si(111) surface in H2-based chemical vapor ambient as well as its atomic structure after contamination-free transfer to ultrahigh vacuum (UHV). Applying complementary UHV-based techniques, we derive a complete picture of the atomic surface structure and its chemical composition. X-ray photoelectron spectroscopy measurements after high-temperature annealing confirm a Si surface free of any traces of oxygen or other impurities. The annealing in H2 ambient leads to a monohydride surface termination, as verified by Fourier-transform infrared spectroscopy. Scanning tunneling microscopy confirms a well ordered, atomically smooth surface, which is (1 × 1) reconstructed, in agreement with low energy electron diffraction patterns. Atomic force microscopy reveals a significant influence of homoepitaxy and wet-chemical pretreatment on the surface morphology. Our findings show that wet-chemical pretreatment followed by high-temperature annealing leads to contamination-free, atomically flat Si(111) surfaces, which are ideally suited for subsequent III-V heteroepitaxy.

  7. Preservation of water samples for arsenic(III/V) determinations: An evaluation of the literature and new analytical results

    USGS Publications Warehouse

    McCleskey, R.B.; Nordstrom, D.K.; Maest, A.S.

    2004-01-01

    Published literature on preservation procedures for stabilizing aqueous inorganic As(III/V) redox species contains discrepancies. This study critically evaluates published reports on As redox preservation and explains discrepancies in the literature. Synthetic laboratory preservation experiments and time stability experiments were conducted for natural water samples from several field sites. Any field collection procedure that filters out microorganisms, adds a reagent that prevents dissolved Fe and Mn oxidation and precipitation, and isolates the sample from solar radiation will preserve the As(III/V) ratio. Reagents that prevent Fe and Mn oxidation and precipitation include HCl, H 2SO4, and EDTA, although extremely high concentrations of EDTA are necessary for some water samples high in Fe. Photo-catalyzed Fe(III) reduction causes As(III) oxidation; however, storing the sample in the dark prevents photochemical reactions. Furthermore, the presence of Fe(II) or SO 4 inhibits the oxidation of As(III) by Fe(III) because of complexation reactions and competing reactions with free radicals. Consequently, fast abiotic As(III) oxidation reactions observed in the laboratory are not observed in natural water samples for one or more of the following reasons: (1) the As redox species have already stabilized, (2) most natural waters contain very low dissolved Fe(III) concentrations, (3) the As(III) oxidation caused by Fe(III) photoreduction is inhibited by Fe(II) or SO4.

  8. A direct thin-film path towards low-cost large-area III-V photovoltaics

    PubMed Central

    Kapadia, Rehan; Yu, Zhibin; Wang, Hsin-Hua H.; Zheng, Maxwell; Battaglia, Corsin; Hettick, Mark; Kiriya, Daisuke; Takei, Kuniharu; Lobaccaro, Peter; Beeman, Jeffrey W.; Ager, Joel W.; Maboudian, Roya; Chrzan, Daryl C.; Javey, Ali

    2013-01-01

    III-V photovoltaics (PVs) have demonstrated the highest power conversion efficiencies for both single- and multi-junction cells. However, expensive epitaxial growth substrates, low precursor utilization rates, long growth times, and large equipment investments restrict applications to concentrated and space photovoltaics (PVs). Here, we demonstrate the first vapor-liquid-solid (VLS) growth of high-quality III-V thin-films on metal foils as a promising platform for large-area terrestrial PVs overcoming the above obstacles. We demonstrate 1–3 μm thick InP thin-films on Mo foils with ultra-large grain size up to 100 μm, which is ~100 times larger than those obtained by conventional growth processes. The films exhibit electron mobilities as high as 500 cm2/V-s and minority carrier lifetimes as long as 2.5 ns. Furthermore, under 1-sun equivalent illumination, photoluminescence efficiency measurements indicate that an open circuit voltage of up to 930 mV can be achieved, only 40 mV lower than measured on a single crystal reference wafer. PMID:23881474

  9. Towards large size substrates for III-V co-integration made by direct wafer bonding on Si

    SciTech Connect

    Daix, N. Uccelli, E.; Czornomaz, L.; Caimi, D.; Rossel, C.; Sousa, M.; Siegwart, H.; Marchiori, C.; Fompeyrine, J.; Hartmann, J. M.; Shiu, K.-T.; Cheng, C.-W.; Krishnan, M.; Lofaro, M.; Kobayashi, M.; Sadana, D.

    2014-08-01

    We report the first demonstration of 200 mm InGaAs-on-insulator (InGaAs-o-I) fabricated by the direct wafer bonding technique with a donor wafer made of III-V heteroepitaxial structure grown on 200 mm silicon wafer. The measured threading dislocation density of the In{sub 0.53}Ga{sub 0.47}As (InGaAs) active layer is equal to 3.5 × 10{sup 9} cm{sup −2}, and it does not degrade after the bonding and the layer transfer steps. The surface roughness of the InGaAs layer can be improved by chemical-mechanical-polishing step, reaching values as low as 0.4 nm root-mean-square. The electron Hall mobility in 450 nm thick InGaAs-o-I layer reaches values of up to 6000 cm{sup 2}/Vs, and working pseudo-MOS transistors are demonstrated with an extracted electron mobility in the range of 2000–3000 cm{sup 2}/Vs. Finally, the fabrication of an InGaAs-o-I substrate with the active layer as thin as 90 nm is achieved with a Buried Oxide of 50 nm. These results open the way to very large scale production of III-V-o-I advanced substrates for future CMOS technology nodes.

  10. Material growth and characterization directed toward improving III-V heterojunction solar cells

    NASA Technical Reports Server (NTRS)

    Stefanakos, E. K.; Alexander, W. E.; Collis, W.; Abul-Fadl, A.

    1979-01-01

    In addition to the existing materials growth laboratory, the photolithographic facility and the device testing facility were completed. The majority of equipment for data acquisition, solar cell testing, materials growth and device characterization were received and are being put into operation. In the research part of the program, GaAs and GaA1As layers were grown reproducibly on GaAs substrates. These grown layers were characterized as to surface morphology, thickness and thickness uniformity. The liquid phase epitaxial growth process was used to fabricate p-n junctions in Ga(1-x)A1(x)As. Sequential deposition of two alloy layers was accomplished and detailed analysis of the effect of substrate quality and dopant on the GaA1As layer quality is presented. Finally, solar cell structures were formed by growing a thin p-GaA1As layer upon an epitaxial n-GaA1As layer. The energy gap corresponding to the long wavelength cutoff of the spectral response characteristic was 1.51-1.63 eV. Theoretical calculations of the spectral response were matched to the measured response.

  11. III-V Solar Cells Based on a Lattice Parameter near that of InP

    NASA Astrophysics Data System (ADS)

    O'Mahony, Donagh; Mathews, Ian; Gocalinska, Agnieszka; Pelucchi, Emanuele; Thomas, Kevin; Morrison, Alan P.; Corbett, Brian

    2014-08-01

    Multi-junction cells based on a lattice constant of 5.816 Å using InAlAs - InGaAsP - InGaAs alloys can theoretically outperform those based on the GaAs lattice parameter by 3%. This lattice constant is close to that of InP (5.86 Å) but ultimately requires growth on a lower cost substrate such as Ge or Si for cost effectiveness. This paper presents an overview of our group's progress on the development of the essential sub-elements of this novel configuration, namely: (i) single-junction In0.52Al0.48As and In0.53Ga0.47As solar cells lattice matched to InP substrates with measured 1-Sun PV efficiencies of 13.8% and 9.3% respectively, (ii) a compositionally-graded InxGa1-xAs/InP metamorphic buffer layer (MBL) that alters the lattice constant from 5.65 Å (GaAs) to 5.87 Å (InP) and (iii) the growth of In0.52Al0.48As and In0.53Ga0.47As single junction cells on GaAs substrates.

  12. Toward the Development of Group III-V Photodetectors and Imaging Arrays

    NASA Technical Reports Server (NTRS)

    Wickenden, Dennis K.

    2003-01-01

    A collaboration between researchers at NASA Goddard Space Flight Center (GSFC) (Code 718.1) and the Johns Hopkins University Applied Physics Laboratory (APL) on the development of gallium nitride (GaN) based photodetectors has been in existence since July 1994. This collaboration, based on APL undertaking the material growth and GSFC undertaking the device processing, has led to discrete GaN photoconductive detectors with superior characteristics to those of similar devices reported in the literature and, more recently, to the development of state-of-the art 256x256 imaging arrays with the pixels indium bump-bonded to a silicon readout circuit (RIOC). The object of this proposal is to continue the collaboration for the period 1998-2002 by outlining a program of work at the APL on the metalorganic chemical vapor deposition (MOCVD) growth of GaN and related materials for UV detector applications. In particular, emphasis will be placed on the optimization of growth on 2 in diameter substrates, on the growth of In(sub x)Ga(1-x)N and Al(sub x)Ga(1-x)N alloy structures to produce devices with a wider range of tailored cut-off wavelengths, and on the growth of pn-junction structures for photovoltaic devices.

  13. Calculation of strain compensation thickness for III-V semiconductor quantum dot superlattices

    NASA Astrophysics Data System (ADS)

    Polly, S. J.; Bailey, C. G.; Grede, A. J.; Forbes, D. V.; Hubbard, S. M.

    2016-11-01

    Models based on continuum elasticity theory are discussed to calculate the necessary thickness of a strain compensation (SC) layer for a superlattice (SL) of strained quantum wells (QW) or quantum dots (QD). These models are then expanded to cover material systems (substrates, QW or QD, and SC) composed of AlP, AlAs, AlSb, GaP, GaAs, GaSb, InP, InAs, or InSb, as well as the ternary, quaternary, and higher order material alloys possible in the Al/Ga/In/P/As/Sb systems. SC thickness calculation methods were compared against dynamical scattering simulations and experimental X-ray diffraction measurements of the InAs/GaP/GaAs QD/SC/Substrate superlattices of varying SC thickness. Based on the reduced (but not eliminated) strain present, a further modified strain compensation thickness is calculated to maximize the number of SL repeat units before the onset of misfit dislocations is also calculated. These models have been assembled into a free application on nanoHUB for use by the community.

  14. Iii-V Compound Multiple Quantum Well Based Modulator and Switching Devices.

    NASA Astrophysics Data System (ADS)

    Hong, Songcheol

    A general formalism to study the absorption and photocurrent in multiple quantum well is provided with detailed consideration of quantum confined Stark shift, exciton binding energy, line broadening, tunneling, polarization, and strain effects. Results on variation of exciton size, binding energies and transition energies as a function electric field and well size have been presented. Inhomogeneous line broadening of exciton lines due to interface roughness, alloy disorder and well to well size fluctuation is calculated. The potential of material tailoring by introducing strain for specific optical response is discussed. Theoretical and experimental results on excitonic and band-to-band absorption spectra in strained multi-quantum well structures are shown. I also report on polarization dependent optical absorption for excitonic and interband transitions in lattice matched and strained multiquantum well structures in presence of transverse electric field. Photocurrent in a p-i(MQW)-n diode with monochromatic light is examined with respect to different temperatures and intensities. The negative resistance of I-V characteristic of the p-i-n diode is based on the quantum confined Stark effect of the heavy hole excitonic transition in a multiquantum well. This exciton based photocurrent characteristic allows efficient switching. A general purpose low power optical logic device using the controller-modulator concept bas been proposed and realized. The controller is a heterojunction phototransistor with multiquantum wells in the base-collector depletion region. This allows an amplified photocurrent controlled voltage feedback with low light intensity levels. Detailed analysis of the sensitivity of this device in various modes of operation is studied. Studies are also presented on the cascadability of the device as well as its integrating -thresholding properties. A multiquantum well heterojunction bipolar transistor (MHBT), which has N^+ -p^+-i(MQW)-N structure has been

  15. Effects of proton irradiation on luminescence and carrier dynamics of self-assembled III-V quatum dots

    NASA Technical Reports Server (NTRS)

    Leon, R.; Marcinkevicius, S.; Siegert, J.; Magness, B.; Taylor, W.; Lobo, C.

    2002-01-01

    The effects of proton irradiation (1.5 MeV) on photoluminescence intensities and carrier dynamics were compared between III-V quantum dots and similar quantum well structures. A significant enhancement in radiation tolerance is seen with three-dimensional quantum confinement. Measurements were carried out in different quantum dot (QD) structures, varying in material (InGaAs/GaAs and InAlAs/AlGaAs), QD surface density (4x10^8 to 3x10'^10 cm^-2), and substrate orientation [(100) and (311) B]. Similar trends were observed for all QD samples. A slight increase in PL emission after low to intermediate proton doses, are also observed in InGaAs/GaAs (100) QD structures. The latter is explained in terms of more efficient carrier transfer from the wetting layer via radiation-induced defects.

  16. Multi-Band and Broad-Band Infrared Detectors Based on III-V Materials for Spectral Imaging Instruments

    NASA Technical Reports Server (NTRS)

    Bandara, S. V.; Gunapala, S. D.; Liu, J. K.; Rafol, S. B.; Hill, C. J.; Ting, D. Z.; Mumolo, J. M.; Trinh, T. Q.

    2005-01-01

    Quantum well infrared photodetector technology has shown remarkable success by realizing large-format focal plane arrays in both broad-bands and in multi-bands. The spectral response of these detectors based on the III-V material system are tailorable within the mid and long wavelength IR bands (similar to 3-25 mu m) and possibly beyond. Multi-band and broad-band detector arrays have been developed by vertically integrating stacks of multi quantum wells tailored for response in different wavelengths bands. Each detector stack absorbs photons within the specified wavelength band while allowing the transmission other photons, thus efficiently permitting multiband detection. Flexibility in many design parameters of these detectors allows for tuning and tailoring the spectral shape according to application requirements, specifically for spectral imaging instruments.

  17. Molecular beam epitaxy engineered III-V semiconductor structures for low-power optically addressed spatial light modulators

    NASA Technical Reports Server (NTRS)

    Larsson, Anders G.; Maserjian, Joseph

    1992-01-01

    Device approaches are investigated for optically addressed SLMs based on molecular-beam epitaxy (MBE) engineered III-V materials and structures. Strong photooptic effects can be achieved in periodically delta-doped multiple-quantum-well structures, but are still insufficient for high-contrast modulation with only single- or double-pass absorption through active layers of practical thickness. The asymmetric Fabry-Perot cavity approach is employed to permit extinction of light due to interference of light reflected from the front and back surfaces of the cavity. This approach is realized with an all-MBE-grown structure consisting of GaAs/AlAs quarter-wave stack reflector grown over the GaAs substrate as the high reflectance mirror and the GaAs surface as the low reflectance mirror. High-contrast modulation is achieved using a low-power InGaAs/GaAs quantum well laser for the control signal.

  18. Monolithic in-based III-V compound semiconductor focal plane array cell with single stage CCD output

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Cunningham, Thomas J. (Inventor); Krabach, Timothy N. (Inventor); Staller, Craig O. (Inventor)

    1995-01-01

    A monolithic semiconductor imager includes an indium-based III-V compound semiconductor monolithic active layer of a first conductivity type, an array of plural focal plane cells on the active layer, each of the focal plane cells including a photogate over a top surface of the active layer, a readout circuit dedicated to the focal plane cell including plural transistors formed monolithically with the monolithic active layer and a single-stage charge coupled device formed monolithically with the active layer between the photogate and the readout circuit for transferring photo-generated charge accumulated beneath the photogate during an integration period to the readout circuit. The photogate includes thin epitaxial semiconductor layer of a second conductivity type overlying the active layer and an aperture electrode overlying a peripheral portion of the thin epitaxial semiconductor layer, the aperture electrode being connectable to a photogate bias voltage.

  19. Monolithic in-based III-V compound semiconductor focal plane array cell with single stage CCD output

    NASA Technical Reports Server (NTRS)

    Fossum, Eric R. (Inventor); Cunningham, Thomas J. (Inventor); Krabach, Timothy N. (Inventor); Staller, Craig O. (Inventor)

    1994-01-01

    A monolithic semiconductor imager includes an indium-based III-V compound semiconductor monolithic active layer of a first conductivity type, an array of plural focal plane cells on the active layer, each of the focal plane cells including a photogate over a top surface of the active layer, a readout circuit dedicated to the focal plane cell including plural transistors formed monolithically with the monolithic active layer and a single-stage charge coupled device formed monolithically with the active layer between the photogate and the readout circuit for transferring photo-generated charge accumulated beneath the photogate during an integration period to the readout circuit. The photogate includes thin epitaxial semiconductor layer of a second conductivity type overlying the active layer and an aperture electrode overlying a peripheral portion of the thin epitaxial semiconductor layer, the aperture electrode being connectable to a photogate bias voltage.

  20. Atomic-scale studies of nanometer-sized graphene on III-V semiconductors using scanning tunneling microscopy.

    NASA Astrophysics Data System (ADS)

    He, Kevin; Koepke, Justin; Lyding, Joseph

    2009-03-01

    We utilize the Dry Contact Transfer (DCT) method [1] to deposit nanometer-sized, monolayer graphene flakes, in situ, onto cleaved GaAs (110) and InAs (110) surfaces. The flakes were characterized using a homebuilt, room temperature, ultrahigh-vacuum scanning tunneling microscope. We report on the apparent electronic semi-transparency of the monolayer graphene flakes, such that the underlying III-V semiconductor lattice is revealed in our topographic images. This transparency is strongly dependent on the applied sample bias, similar to results seen on SiC (1000) for large sheets of graphene grown via thermal desorption [2]. [3pt] [1] P.M. Albrecht and J.W. Lyding, APL 83, 5029 (2003). [0pt] [2] G.M. Rutter et al, Phys. Rev. B 76, 235416 (2007).

  1. Scalable, epitaxy-free fabrication of super-absorbing sparse III-V nanowire arrays for photovoltaic applications (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Cheng, Wen-Hui; Fountaine, Katherine T.; Bukowsky, Colton R.; Atwater, Harry A.

    2016-09-01

    III-V compound semiconductor nanowire arrays are promising candidates for photovoltaics applications due to their high volumetric absorption. Uniform nanowire arrays exhibit high absorption at certain wavelengths due to strong coupling into lossy waveguide modes. Previously, simulations predicted near-unity, broadband absorption in sparse semiconductor nanowire arrays (<5% fill fraction) with multi-radii and tapered nanowire array designs [1]. Herein, we experimentally demonstrate near-unity broadband absorption in InP nanowire arrays via a scalable, epitaxy-free fabrication method, using nanoimprint lithography and ICP-RIE to define nanowire arrays in bulk InP wafers. In addition to mask pattern design (wire radius and spacing) and etch chemistry (wire taper), appropriate selection of a hard mask for the InP etch is critical to precise dimension control and reproducibility. Polymer-embedded wires are removed from the bulk InP substrate by a mechanical method that facilitates extensive reuse of a single bulk InP wafer to synthesize many polymer-embedded nanowire array thin films. Arrays containing multiple nanowire radii and tapered nanowires were successfully fabricated. For both designs, the polymer-embedded arrays achieved 90% broadband absorption (λ=400-900 nm) in less than 100 nm planar equivalence of InP. The addition of a silver back reflector increased this broadband absorption to 95%. The repeatable process of imprinting, etching and peeling to obtain many nanowire arrays from one single wafer represents an economical manufacturing route for high efficiency III-V photovoltaics. [1] K.T. Fountaine, C.G. Kendall, Harry A. Atwater, "Near-unity broadband absorption designs for semiconducting nanowire arrays via localized radial mode excitation," Opt. Exp. (2014).

  2. Predicted Growth of Two-Dimensional Topological Insulators Consisting of Hydrogenated III-V Thin films on Si(111) Substrate

    NASA Astrophysics Data System (ADS)

    Chuang, Feng-Chuan; Crisostomo, Christian; Yao, Liang-Zi; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Lin, Hsin; Albao, Marvin; Bansil, Arun

    We have carried out systematic first-principles electronic structure calculations of growth of ultrathin films of compounds of group III (B, Al, In, Ga and Tl) with group V (N, P, As, Sb and Bi) elements on Si(111) substrate, including effects of hydrogenation. A total of six compounds (GaBi, InBi, TlBi, TlAs, TlSb and TlN) are identified to be nontrivial in unhydrogenated case; whereas for hydrogenated case, only four (GaBi, InBi, TlBi and TlSb) remains nontrivial. The band gap is found to be as large as 855 meV for the hydrogenated TlBi film, making this class of III-V materials suitable for room temperature applications. TlBi remains topologically nontrivial with a large band gap at various hydrogen coverages, indicating the robustness of its band topology against bonding effects of substrates. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN and TlBi which can be driven into the nontrivial phase via strain. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.

  3. Chemical trends of stability and band alignment of lattice-matched II-VI/III-V semiconductor interfaces

    NASA Astrophysics Data System (ADS)

    Deng, Hui-Xiong; Luo, Jun-Wei; Wei, Su-Huai

    2015-02-01

    Using the first-principles density functional theory method, we systematically investigate the structural and electronic properties of heterovalent interfaces of the lattice-matched II-VI/III-V semiconductors, i.e., ZnTe/GaSb, ZnSe/GaAs, ZnS/GaP, and ZnO/GaN. We find that, independent of the orientations, the heterovalent superlattices with period n =6 are energetically more favorable to form nonpolar interfaces. For the [001] interface, the stable nonpolar interfaces are formed by mixing 50% group-III with 50% group-II atoms or by mixing 50% group-V with 50% group-VI atoms; for the [111] nonpolar interfaces, the mixings are 25% group-III (II) and 75% group-II (III) atoms or 25% group-V (VI) and 75% group-VI (V) atoms. For all the nonpolar interfaces, the [110] interface has the lowest interfacial energy because it has the minimum number of II-V or III-VI "wrong bonds" per unit interfacial area. The interfacial energy increases when the atomic number of the elements decreases, except for the ZnO/GaN system. The band alignments between the II-VI and III-V compounds are drastically different depending on whether they have mixed-cation or mixed-anion interfaces, but the averaged values are nearly independent of the orientations. Similarly, other than ZnO/GaN, the valence-band offsets also increase as the atomic number of the elements decreases. The abnormal trends in interfacial energy and band alignment for ZnO/GaN are primarily attributed to the very short bond lengths in this system. The underlying physics behind these trends are explained.

  4. Removal of Arsenic (III, V) from aqueous solution by nanoscale zero-valent iron stabilized with starch and carboxymethyl cellulose

    PubMed Central

    2014-01-01

    In this work, synthetic nanoscale zerovalent iron (NZVI) stabilized with two polymers, Starch and Carboxymethyl cellulose (CMC) were examined and compared for their ability in removing As (III) and As (V) from aqueous solutions as the most promising iron nanoparticles form for arsenic removal. Batch operations were conducted with different process parameters such as contact time, nanoparticles concentration, initial arsenic concentration and pH. Results revealed that starch stabilized particles (S-nZVI) presented an outstanding ability to remove both arsenate and arsenite and displayed ~ 36.5% greater removal for As (V) and 30% for As (III) in comparison with CMC-stabilized nanoparticles (C-nZVI). However, from the particle stabilization viewpoint, there is a clear trade off to choosing the best stabilized nanoparticles form. Removal efficiency was enhanced with increasing the contact time and iron loading but reduced with increasing initial As (III, V) concentrations and pH. Almost complete removal of arsenic (up to 500 μg/L) was achieved in just 5 min when the S-nZVI mass concentration was 0.3 g/L and initial solution pH of 7 ± 0.1. The maximum removal efficiency of both arsenic species was obtained at pH = 5 ± 0.1 and starched nanoparticles was effective in slightly acidic and natural pH values. The adsorption kinetics fitted well with pseudo-second-order model and the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 14 mg/g for arsenic (V), and 12.2 mg/g for arsenic (III). It could be concluded that starch stabilized Fe0 nanoparticles showed remarkable potential for As (III, V) removal from aqueous solution e.g. contaminated water. PMID:24860660

  5. Tunable Optical Phenomena and Carrier Recombination Dynamics in III-V Semiconductor Nanostructures

    NASA Astrophysics Data System (ADS)

    Kumar Thota, Venkata Ramana

    Semiconductor nanostructures such as quantum dots, quantum wires and quantum wells have gained significant attention in the scientific community due to their peculiar properties, which arise from the quantum confinement of charge carriers. In such systems, confinement plays key role and governs the emission spectra. With the advancements in growth techniques, which enable the fabrication of these nanostructured devices with great precision down to the atomic scale, it is intriguing to study and observe quantum mechanical effects through light-matter interactions and new physics governed by the confinement, size, shape and alloy composition. The goal is to reduce the size of semiconductor bulk material to few nanometers, which in turn localizes the charge carriers inside these structures such that the spin associated with them is used to carry and process information within ultra-short time scales. The main focus of this dissertation is the optical studies of quantum dot molecule (QDM) systems. A system where the electrons can tunnel between the two dots leading to observable tunneling effects. The emission spectra of such system has been demonstrated to have both intradot transitions (electron-hole pair residing in the same dot) and interdot transitions (electron-hole pair participating in the recombination origin from different dots). In such a system, it is possible to apply electric field such that the wavefunction associated with the charge carriers can be tuned to an extent of delocalizing between the two dots. This forms the first project of this dissertation, which addresses the origin of the fine structure splitting in the exciton-biexciton cascade. Moreover, we also show how this fine structure can be tuned in the quantum dot molecule system with the application of electric field along the growth direction. This is demonstrated through high resolution polarization dependent photoluminescence spectroscopy on a single QDM, which was described in great detail

  6. Understanding the Potential and Limitations of Dilute Nitride Alloys for Solar Cells

    SciTech Connect

    Kurtz, S.; Ptak, A.; Johnston, S.; Kramer, C.; Young, M.; Friedman, D.; Geisz, J.; McMahon, W.; Kibbler, A.; Olson, J.; Crandall, R.; Branz, H.

    2005-11-01

    Dilute nitride alloys provide a powerful tool for engineering the band gap and lattice constant of III-V alloys. However, nitrogen degrades the performance of GaAs solar cells. This project seeks to understand and demonstrate the limits of performance of GaInNAs alloys by (a) correlating deep-level transient spectroscopy (DLTS) data with device performance and (b) using molecular beam epitaxy (MBE) to reduce background impurity concentrations.

  7. Surface and Interfacial Properties of Ga0.47In0.53As Alloys.

    DTIC Science & Technology

    2014-09-26

    S. TYPE OF REPORT & PERIOD COVERED Surface and Interfacial Properties of Final Report Ga0 471n0 53As Alloys April 1. 󈨘 to March 31,󈨙S. PERFORMING...for growing binary and ternary III-V alloy semiconducting layers. Gallium arsenide layers grown with this MBE system have electrical properties which... properties and impurity * 2 doping with both donors and acceptors of this system. However, the availability of the two ternary alloys : Ino 52A10 48As

  8. MOCVD Growth of III-V Photodetectors and Light Emitters for Integration of Optoelectronic Devices on Si substrates

    NASA Astrophysics Data System (ADS)

    Geng, Yu

    With the increase of clock speed and wiring density in integrated circuits, inter-chip and intra-chip interconnects through conventional electrical wires encounter increasing difficulties because of the large power loss and bandwidth limitation. Optical interconnects have been proposed as an alternative to copper-based interconnects and are under intense study due to their large data capacity, high data quality and low power consumption. III-V compound semiconductors offer high intrinsic electron mobility, small effective electron mass and direct bandgap, which make this material system advantageous for high-speed optoelectronic devices. The integration of III-V optoelectronic devices on Si substrates will provide the combined advantage of a high level of integration and large volume production of Si-based electronic circuitry with the superior electrical and optical performance of III-V components, paving the way to a new generation of hybrid integrated circuits. In this thesis, the direct heteroepitaxy of photodetectors (PDs) and light emitters using metal-organic chemical vapor deposition for the integration of photonic devices on Si substrates were studied. First we studied the selective-area growth of InP/GaAs on patterned Si substrates for PDs. To overcome the loading effect, a multi-temperature composite growth technique for GaAs was developed. By decreasing various defects such as dislocations and anti-phase domains, the GaAs and InP buffer layers are with good crystalline quality and the PDs show high speed and low dark current performance both at the edge and center of the large growth well. Then the growth and fabrication of GaAs/AlGaAs QW lasers were studied. Ellipsometry was used to calibrate the Al composition of AlGaAs. Thick p and n type AlGaAs with a mirrorlike surface were grown by high V/III ratio and high temperature. The GaAs/AlGaAs broad area QW laser was successfully grown and fabricated on GaAs substrate and showed a pulsed lasing result

  9. Iii-V Compound Semiconductor Integrated Charge Storage Structures for Dynamic and Non-Volatile Memory Elements

    NASA Astrophysics Data System (ADS)

    Hetherington, Dale Laird

    This thesis presents an investigation into a novel group of GaAs charge storage devices. These devices, which are an integration of bipolar and junction field effect transistor structures were conceived, designed, fabricated, and tested within this study. The purpose was to analyse new types of charge storage devices, which are suitable for fabrication and lead to the development of dynamic and nonvolatile memories in III-V compound semiconductors. Currently, III-V semiconductor storage devices consist only of capacitors, where data is destroyed during reading and electrical erasure is difficult. In this work, four devices types were demonstrated that exhibit nondestructive reading, and three of the prototypes can be electrically erased. All types use the junction field effect transistor (JFET) for charge sensing, with each having different bipolar or epitaxial layer structure controlling the junction gate. The bottom epitaxial layer in each case served as the JFET channel. Two of the device types have three alternately doped layers, while the remaining two have four alternately doped layers. In all cases, removal of majority carriers from the middle layers constitutes stored charge. The missing carriers deplete the current carrying a region of the JFET channel. Drain current of the JFET becomes an indicator of stored charge. The basic function of each JFET memory element type is independent of interchanging n- and p- type doping within the structure type. Some performance advantage can be realized, however, by sensing with an n-type channel as compared to p- type due to increased carrier mobility. All device types exhibit storage time characteristics of order ten seconds. Devices are constructed in epitaxial layers grown by molecular beam epitaxy (MBE) reactors. The design of the epitaxial layers is an intrinsic part, together with the electrical design, of the storage device concept. These concepts are implemented first with photolithography masks which are used

  10. In situ preparation of Si p-n junctions and subsequent surface preparation for III-V heteroepitaxy in MOCVD ambient

    NASA Astrophysics Data System (ADS)

    Paszuk, Agnieszka; Dobrich, Anja; Koppka, Christian; Brückner, Sebastian; Duda, Marek; Kleinschmidt, Peter; Supplie, Oliver; Hannappel, Thomas

    2017-04-01

    III-V integration on active Si-bottom cells promises not only high-efficiency multi-junction solar cells but also lower production costs. In situ preparation of an adequate Si p-n junction in metalorganic chemical vapor deposition ambient is challenging, particularly since the final Si surface should be atomically well-ordered to enable low-defect III-V nucleation. Precisely, a single-domain Si(100) surface with double layer steps needs to be prepared in order to suppress antiphase disorder in subsequently grown III-V layer structures on top of the Si p-n junction. We first investigate the formation of a n+-type collector in Si(100) as a result of annealing in tertiarybutylphosphine (TBP) or tertiarybutylarsine (TBAs) ambient. We illustrate how the n-type doping concentrations and their depth profiles depend on the essential preparation parameters, such as precursor partial pressures, exposure and annealing time, as well as reactor pressure. Subsequently, by applying in situ reflectance anisotropy spectroscopy, we find that exposure of Si(100) to TBP or TBAs leads to atomic disorder on the surface. Further, we apply an additional annealing step without precursor supply leading to predominantly (1×2) reconstructed Si(100) surfaces, which are suitable for subsequent low-defect III-V growth.

  11. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate

    SciTech Connect

    Yao, Liang-Zi; Crisostomo, Christian P.; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2015-11-05

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.

  12. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate

    DOE PAGES

    Yao, Liang-Zi; Crisostomo, Christian P.; Yeh, Chun-Chen; ...

    2015-11-05

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One andmore » two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.« less

  13. Are Electro-Luminescence Defects in Concentrator Iii-V Cells Responsible to Thermal Runaway and Sudden Death?

    NASA Astrophysics Data System (ADS)

    Araki, Kenji; Al Taher, Omar; Nagai, Hirokazu; Hebert, Peter; Valles, Juan

    2011-12-01

    Two types of failure of III-V cells in CPV system by Daido Steel have been observed. One is thermal runaway and another is what we call a electrical shock. This paper will discuss on the frequency of the cell failure seen in a field and on experiments to determine the root cause of thermal runaway. Failures by the electrical shock were not related to thermal runaway, and a packaging solution to the failure by the electrical shock was found which will be published at another time. A detailed investigation of 30 kW field was undertaken to identify failed cells. After the other failure mechanism has been removed, experiments can be conducted on thermal runaway. Thermal runaway can occur due to loss of thermal conduction, such as voids or discontinuities in the thermal interchange material bonding cell to heat sink. It has been hypothesized that thermal runaway can also occur at location of cell defects as identified by electroluminescence. So far it we have not been able to induce thermal runaway at locations of electroluminescence defects.

  14. Impact of photon recycling and luminescence coupling on III-V single and dual junction photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Walker, Alexandre W.; Höhn, Oliver; Micha, Daniel N.; Wagner, Lukas; Helmers, Henning; Bett, Andreas W.; Dimroth, Frank

    2015-01-01

    Modeling single junction solar cells composed of III-V semiconductors such as GaAs with the effects of photon recycling yields insight into design and material criteria required for high efficiencies. For a thin-film single junction GaAs cell to reach 28.5% efficiency, simulation results using a recently developed model which accounts for photon recycling indicate that Shockley-Read-Hall (SRH) lifetimes of electrons and holes must be longer than 3 and 1 μs, respectively, in a 2-μm thin active region, and that the native substrate must be removed such that the cell is coupled to a highly reflective rear-side mirror. The model is generalized to account for luminescence coupling in tandem devices, which yields direct insight into the top cell's nonradiative lifetimes. A heavily current mismatched GaAs/GaAs tandem device is simulated and measured experimentally as a function of concentration between 3 and 100 suns. The luminescence coupling increases from 14% to 33% experimentally, whereas the model requires increasing electron and hole SRH lifetimes to explain these results. This could be an indication of the saturating defects which mediate the SRH process. However, intermediate GaAs layers between the two subcells may also contribute to the luminescence coupling as a function of concentration.

  15. III-V compound semiconductor multi-junction solar cells fabricated by room-temperature wafer-bonding technique

    NASA Astrophysics Data System (ADS)

    Arimochi, Masayuki; Watanabe, Tomomasa; Yoshida, Hiroshi; Tange, Takashi; Nomachi, Ichiro; Ikeda, Masao; Dai, Pan; He, Wei; Ji, Lian; Lu, Shulong; Yang, Hui; Uchida, Shiro

    2015-05-01

    We have developed III-V compound semiconductor multi-junction solar cells by a room-temperature wafer-bonding technique to avoid the formation of dislocations and voids due to lattice mismatch and thermal damage during a conventional high-temperature wafer-bonding process. First, we separately grew an (Al)GaAs top cell on a GaAs substrate and an InGaAs bottom cell on an InP substrate by metal solid source molecular beam epitaxy. Thereafter, we successfully bonded these sub-cells by the room-temperature wafer-bonding technique and fabricated (Al)GaAs ∥ InGaAs wafer-bonded solar cells. To the best of our knowledge, the obtained GaAs ∥ InGaAs and AlGaAs ∥ InGaAs wafer-bonded solar cells exhibited the lowest electrical and optical losses ever reported. The AlGaAs ∥ InGaAs solar cells reached the maximum efficiency of 27.7% at 120 suns. These results suggest that the room-temperature wafer-bonding technique has high potential for achieving higher conversion efficiencies.

  16. Substrate-supported large-band-gap quantum spin Hall insulator based on III-V bismuth layers

    NASA Astrophysics Data System (ADS)

    Padilha, J. E.; Janotti, A.; Fazzio, A.; da Silva, A. J. R.

    2016-11-01

    We show that III-V bismuth-based two-dimensional (2D) materials grown on an anion-terminated SrTe (111) substrate are 2D topological insulators. The III-Bi layers exhibit large nontrivial band gaps, ranging from 0.15 to 0.72 eV, depending on the passivation on the top surface, i.e., using hydrogen or halogens. We find that Γ -centered Dirac helical states, protected by time-reversal symmetry, appear at the edges of nanoribbon structures made of III-Bi layers on the SrTe substrate. The nontrivial character of the band gap is also determined by calculations of the Z2 invariant. We also find that the topological phase is maintained in the ultrathin quantum well heterostructures SrTe/III-Bi/SrTe, i.e., when the 2D materials are sandwiched between SrTe along the [111] direction, opening a new route for the fabrication of nanostructured devices based on 2D quantum spin Hall insulators.

  17. Rapid 2D incoherent mirror fabrication by laser interference lithography and wet etching for III-V MQW solar cells

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Freundlich, Alex

    2016-03-01

    Optimization of non-planar antireflective coating and back- (or front-) surface texturing are widely studied as advanced light management approach to further reduce the reflection losses and increase the sunlight absorption path in solar cells. Rear reflectors have been developed from coherent mirrors to incoherent mirrors in order to further increase light path, which can significantly improve the efficiency and allow for much thinner devices. A Lambertian surface, which has the most random texture, can theoretically raise the light path to 4n2 times that of a smooth surface. It's a challenge however to fabricate ideal Lambertian texture, especially in a fast and low cost way. In this work, a method is developed to overcome this challenge that combines the use of laser interference lithography (LIL) and selective wet etching. This approach allows for a rapid (10 min) wafer scale (3 inch wafer) texture processing with sub-wavelength (nano)-scale control of the pattern and the pitch. The technique appears as being particularly attractive for the development of ultrathin III-V devices, or in overcoming the weak sub-bandgap absorption in devices incorporating quantum dots or quantum wells. The structure of the device is demonstrated, without affecting active layers.

  18. Ion beam nanopatterning of III-V semiconductors: consistency of experimental and simulation trends within a chemistry-driven theory

    PubMed Central

    El-Atwani, O.; Norris, S. A.; Ludwig, K.; Gonderman, S.; Allain, J. P.

    2015-01-01

    Several proposed mechanisms and theoretical models exist concerning nanostructure evolution on III-V semiconductors (particularly GaSb) via ion beam irradiation. However, making quantitative contact between experiment on the one hand and model-parameter dependent predictions from different theories on the other is usually difficult. In this study, we take a different approach and provide an experimental investigation with a range of targets (GaSb, GaAs, GaP) and ion species (Ne, Ar, Kr, Xe) to determine new parametric trends regarding nanostructure evolution. Concurrently, atomistic simulations using binary collision approximation over the same ion/target combinations were performed to determine parametric trends on several quantities related to existing model. A comparison of experimental and numerical trends reveals that the two are broadly consistent under the assumption that instabilities are driven by chemical instability based on phase separation. Furthermore, the atomistic simulations and a survey of material thermodynamic properties suggest that a plausible microscopic mechanism for this process is an ion-enhanced mobility associated with energy deposition by collision cascades. PMID:26670948

  19. Interface simulation of strained and non-abrupt III-V quantum wells. Part 1: band profile calculation

    NASA Astrophysics Data System (ADS)

    Lamberti, C.

    1996-01-01

    This work presents a program, based on the Van de Walle-Martin model solid theory, able to compute the most important physical quantities of any In 1- xGa xAs yP 1- y quaternary epitaxially strained growth on any In 1- zGa zAs wP 1- w hypothetical substrate. The adopted interface-band alignment procedure is extensively described. The effect of strain on several examples of ideal heterostructures characterized by abrupt interfaces is discussed in detail. Furthermore, the problem of a composition gradient spread over some monolayers at the interfaces of III-V quantum wells and superlattices, due to the technological problems in group V switches in the present epitaxial techniques is treated extensively. The interface layers are thus non-intentionally strained on the substrate lattice parameter causing a local change in the bands profile along the growth direction. The differences between an ideal rectangular potential and the real profile are shown. The output files of this program consist in the band profiles for electrons, heavy and light holes, which will be used by the program PLSIMUL (described in a subsequent article) to compute the corresponding quantized levels to be compared with experimental 4 K photoluminescence data.

  20. III-V tri-gate quantum well MOSFET: Quantum ballistic simulation study for 10 nm technology and beyond

    NASA Astrophysics Data System (ADS)

    Datta, Kanak; Khosru, Quazi D. M.

    2016-04-01

    In this work, quantum ballistic simulation study of a III-V tri-gate MOSFET has been presented. At the same time, effects of device parameter variation on ballistic, subthreshold and short channel performance is observed and presented. The ballistic simulation result has also been used to observe the electrostatic performance and Capacitance-Voltage characteristics of the device. With constant urge to keep in pace with Moore's law as well as aggressive scaling and device operation reaching near ballistic limit, a full quantum transport study at 10 nm gate length is necessary. Our simulation reveals an increase in device drain current with increasing channel cross-section. However short channel performance and subthreshold performance get degraded with channel cross-section increment. Increasing device cross-section lowers threshold voltage of the device. The effect of gate oxide thickness on ballistic device performance is also observed. Increase in top gate oxide thickness affects device performance only upto a certain value. The thickness of the top gate oxide however shows no apparent effect on device threshold voltage. The ballistic simulation study has been further used to extract ballistic injection velocity of the carrier and ballistic carrier mobility in the channel. The effect of device dimension and gate oxide thickness on ballistic velocity and effective carrier mobility is also presented.

  1. Predicted Growth of Two-Dimensional Topological Insulator Thin Films of III-V Compounds on Si(111) Substrate

    NASA Astrophysics Data System (ADS)

    Yao, Liang-Zi; Crisostomo, Christian P.; Yeh, Chun-Chen; Lai, Shu-Ming; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2015-11-01

    We have carried out systematic first-principles electronic structure computations of growth of ultrathin films of compounds of group III (B, Al, In, Ga, and Tl) with group V (N, P, As, Sb, and Bi) elements on Si(111) substrate, including effects of hydrogenation. Two bilayers (BLs) of AlBi, InBi, GaBi, TlAs, and TlSb are found to support a topological phase over a wide range of strains, in addition to BBi, TlN, and TlBi which can be driven into the nontrivial phase via strain. A large band gap of 134 meV is identified in hydrogenated 2 BL film of InBi. One and two BL films of GaBi and 2 BL films of InBi and TlAs on Si(111) surface possess nontrivial phases with a band gap as large as 121 meV in the case of 2 BL film of GaBi. Persistence of the nontrivial phase upon hydrogenations in the III-V thin films suggests that these films are suitable for growing on various substrates.

  2. Ion beam nanopatterning of III-V semiconductors: Consistency of experimental and simulation trends within a chemistry-driven theory

    DOE PAGES

    El-Atwani, O.; Norris, S. A.; Ludwig, K.; ...

    2015-12-16

    In this study, several proposed mechanisms and theoretical models exist concerning nanostructure evolution on III-V semiconductors (particularly GaSb) via ion beam irradiation. However, making quantitative contact between experiment on the one hand and model-parameter dependent predictions from different theories on the other is usually difficult. In this study, we take a different approach and provide an experimental investigation with a range of targets (GaSb, GaAs, GaP) and ion species (Ne, Ar, Kr, Xe) to determine new parametric trends regarding nanostructure evolution. Concurrently, atomistic simulations using binary collision approximation over the same ion/target combinations were performed to determine parametric trends onmore » several quantities related to existing model. A comparison of experimental and numerical trends reveals that the two are broadly consistent under the assumption that instabilities are driven by chemical instability based on phase separation. Furthermore, the atomistic simulations and a survey of material thermodynamic properties suggest that a plausible microscopic mechanism for this process is an ion-enhanced mobility associated with energy deposition by collision cascades.« less

  3. Ion beam nanopatterning of III-V semiconductors: Consistency of experimental and simulation trends within a chemistry-driven theory

    SciTech Connect

    El-Atwani, O.; Norris, S. A.; Ludwig, K.; Gonderman, S.; Allain, J. P.

    2015-12-16

    In this study, several proposed mechanisms and theoretical models exist concerning nanostructure evolution on III-V semiconductors (particularly GaSb) via ion beam irradiation. However, making quantitative contact between experiment on the one hand and model-parameter dependent predictions from different theories on the other is usually difficult. In this study, we take a different approach and provide an experimental investigation with a range of targets (GaSb, GaAs, GaP) and ion species (Ne, Ar, Kr, Xe) to determine new parametric trends regarding nanostructure evolution. Concurrently, atomistic simulations using binary collision approximation over the same ion/target combinations were performed to determine parametric trends on several quantities related to existing model. A comparison of experimental and numerical trends reveals that the two are broadly consistent under the assumption that instabilities are driven by chemical instability based on phase separation. Furthermore, the atomistic simulations and a survey of material thermodynamic properties suggest that a plausible microscopic mechanism for this process is an ion-enhanced mobility associated with energy deposition by collision cascades.

  4. Ion beam nanopatterning of III-V semiconductors: consistency of experimental and simulation trends within a chemistry-driven theory

    NASA Astrophysics Data System (ADS)

    El-Atwani, O.; Norris, S. A.; Ludwig, K.; Gonderman, S.; Allain, J. P.

    2015-12-01

    Several proposed mechanisms and theoretical models exist concerning nanostructure evolution on III-V semiconductors (particularly GaSb) via ion beam irradiation. However, making quantitative contact between experiment on the one hand and model-parameter dependent predictions from different theories on the other is usually difficult. In this study, we take a different approach and provide an experimental investigation with a range of targets (GaSb, GaAs, GaP) and ion species (Ne, Ar, Kr, Xe) to determine new parametric trends regarding nanostructure evolution. Concurrently, atomistic simulations using binary collision approximation over the same ion/target combinations were performed to determine parametric trends on several quantities related to existing model. A comparison of experimental and numerical trends reveals that the two are broadly consistent under the assumption that instabilities are driven by chemical instability based on phase separation. Furthermore, the atomistic simulations and a survey of material thermodynamic properties suggest that a plausible microscopic mechanism for this process is an ion-enhanced mobility associated with energy deposition by collision cascades.

  5. Optimising the defect filter layer design for III/V QDs on Si for integrated laser applications

    NASA Astrophysics Data System (ADS)

    Orchard, Jonathan R.; Wu, Jiang; Chen, Siming; Jiang, Qi; Ward, Thomas; Beanland, Richard; Lui, Huiyun; Mowbray, David

    2015-02-01

    We introduce the concept of using strained superlattice structures as defect filters, with their purpose to reduce the upwards propagation of dislocations that result from the lattice mismatch which occurs when III-V materials are grown on silicon substrates. Three samples with defect filter layers are grown on Si with and without in situ annealing and are compared to a similar structure grown on a GaAs substrate. Transmission electron microscopy is used to verify the effectiveness of the different designs grown on Si, with the twice-annealed sample reducing the number of defects present in the active region by 99.9%. Optical studies carried out exhibit brighter room temperature emission and reduced photoluminescence quenching with temperature in samples where annealing is performed. Photoluminescence excitation measurements reveal a ~20 meV redshift in the position of the GaAs exciton for the samples grown on Si compared to that of GaAs, indicating a residual inplane tensile strain ~0.35% in the GaAs of the active region for the samples grown on Si.

  6. Fast pixelated sensors for radiation detection and imaging based on quantum confined structures in III/V semiconductors

    NASA Astrophysics Data System (ADS)

    Tortora, M.; Biasiol, G.; Cautero, G.; Menk, R. H.; Plaisier, J. R.; Antonelli, M.

    2017-03-01

    In order to improve the characterisation of the delivered beams in many types of photon sources, innovative beam profilers based on III/V semiconductor materials (InGaAs/InAlAs) have been deeply investigated. Owing to a tunable and direct band gap these devices allow radiation detection in a wide spectral range. In order to increase the sensitivity of the device in radiation detection charge amplification on the sensor level is implemented. This is obtained by exploiting In0.75Ga0.25As/In0.75Al0.25As quantum wells (QW) hosting a two-dimensional electron gas (2DEG) through molecular beam epitaxy (MBE). Internal charge-amplification mechanism can be achieved for very low applied voltages, while the high carrier mobility allows the design of very fast photon detectors with sub-nanosecond response times. This technology has been preliminarily exploited to fabricate prototype beam profilers with a strip geometry (with 50-μm-wide strips). Tests were carried out both with conventional X-ray tubes and at the Elettra synchrotron facility. The results testify how these profilers are capable of reconstructing the shape of the beam, as well as estimating the position of the beam centroid with a precision of about 400 nm. Further measurements with different samples of decreasing thickness have shown how this precision could be further improved by an optimised microfabrication. For this reason a new design, based on a membrane-photodetector, is proposed. Results regarding the spatial resolution as function of the sensor thickness will be presented and discussed.

  7. Soil attenuation of As(III, V) and Se(IV, VI) seepage potential at ash disposal facilities.

    PubMed

    Hyun, Seunghun; Lee, Linda S

    2013-11-01

    Leachate from ash landfills is frequently enriched with As and Se but their off-site movement is not well understood. The attenuation potential of As and Se by soils surrounding selected landfills during leachate seepage was investigated in laboratory column studies using simulated ash leachate. As(III, V) and Se(IV, VI) concentrations as well as pH, flow rate, and a tracer were monitored in influent and effluent for up to 800 pore volumes followed by sequential desorption, extraction, and digestion of column segments. Column breakthrough curves (BTCs) were compared to predictions based on previously measured sorption isotherms. Early As(V) breakthrough and retarded As(III) breakthrough relative to predicted BTCs are indicative of oxidative transformation during seepage. For Se(VI), which exhibits linear sorption and the lowest sorption propensity, measured BTCs were predicted fairly well by equilibrium sorption isotherms, except for the early arrival of Se(IV) in one site soil, which in part, may be due to higher column pH values compared to batch isotherms. Most of the As and Se retained by soils during leaching was found to be strongly sorbed (60-90%) or irreversibly bound (10-40%) with <5% readily desorbable. Redox potential favoring transformation to the more sorptive valence states of As(V) and Se(IV) will invoke additional attenuation beyond equilibrium sorption-based predictions. With the exception of Se(IV) on one site soil, results indicate that attenuation by down-gradient soils of As and Se in ash landfill seepage will often be no less than what is predicted by equilibrium sorption capacity with further attenuation expected due to favorable redox transformation processes, thus mitigating contaminant plumes and associated risks.

  8. III-V-on-nothing metal-oxide-semiconductor field-effect transistors enabled by top-down nanowire release process: Experiment and simulation

    NASA Astrophysics Data System (ADS)

    Gu, J. J.; Koybasi, O.; Wu, Y. Q.; Ye, P. D.

    2011-09-01

    III-V-on-nothing (III-VON) metal-oxide-semiconductor field-effect transistors (MOSFETs) are experimentally demonstrated with In0.53Ga0.47As as channel and atomic layer deposited Al2O3 as gate dielectric. A hydrochloric acid based release process has been developed to create an air gap beneath the InGaAs channel layer, forming the nanowire channel with width down to 40 nm. III-VON MOSFETs with channel lengths down to 50 nm are fabricated and show promising improvement in drain-induced barrier lowering, due to suppressed short-channel effects. The top-down processing technique provides a viable pathway towards fully gate-all-around III-V MOSFETs.

  9. Investigation of the abnormal Zn diffusion phenomenon in III-V compound semiconductors induced by the surface self-diffusion of matrix atoms

    NASA Astrophysics Data System (ADS)

    Tang, Liangliang; Xu, Chang; Liu, Zhuming

    2017-01-01

    Zn diffusion in III-V compound semiconductorsare commonly processed under group V-atoms rich conditions because the vapor pressure of group V-atoms is relatively high. In this paper, we found that group V-atoms in the diffusion sources would not change the shaped of Zn profiles, while the Zn diffusion would change dramatically undergroup III-atoms rich conditions. The Zn diffusions were investigated in typical III-V semiconductors: GaAs, GaSb and InAs. We found that under group V-atoms rich or pure Zn conditions, the double-hump Zn profiles would be formed in all materials except InAs. While under group III-atoms rich conditions, single-hump Zn profiles would be formed in all materials. Detailed diffusion models were established to explain the Zn diffusion process; the surface self-diffusion of matrix atoms is the origin of the abnormal Zn diffusion phenomenon.

  10. Position-controlled III-V compound semiconductor nanowire solar cells by selective-area metal-organic vapor phase epitaxy.

    PubMed

    Fukui, Takashi; Yoshimura, Masatoshi; Nakai, Eiji; Tomioka, Katsuhiro

    2012-01-01

    We demonstrate position-controlled III-V semiconductor nanowires (NWs) by using selective-area metal-organic vapor phase epitaxy and their application to solar cells. Efficiency of 4.23% is achieved for InP core-shell NW solar cells. We form a 'flexible NW array' without a substrate, which has the advantage of saving natural resources over conventional thin film photovoltaic devices. Four junction NW solar cells with over 50% efficiency are proposed and discussed.

  11. 30 CFR 57.22234 - Actions at 1.0 percent methane (I-A, I-B, III, V-A, and V-B mines).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Actions at 1.0 percent methane (I-A, I-B, III...-UNDERGROUND METAL AND NONMETAL MINES Safety Standards for Methane in Metal and Nonmetal Mines Ventilation § 57.22234 Actions at 1.0 percent methane (I-A, I-B, III, V-A, and V-B mines). (a) If methane reaches...

  12. 30 CFR 57.22234 - Actions at 1.0 percent methane (I-A, I-B, III, V-A, and V-B mines).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Actions at 1.0 percent methane (I-A, I-B, III...-UNDERGROUND METAL AND NONMETAL MINES Safety Standards for Methane in Metal and Nonmetal Mines Ventilation § 57.22234 Actions at 1.0 percent methane (I-A, I-B, III, V-A, and V-B mines). (a) If methane reaches...

  13. Surface reactions during the atomic layer deposition of high-kappa dielectrics on III-V semiconductor surfaces

    NASA Astrophysics Data System (ADS)

    Ye, Liwang

    The quality of the dielectric/semiconductor interface is one of the most critical parameters for the fabrication of high-speed and low-power-consumption III-V semiconductor based metal-oxide-semiconductor field effect transistors (MOSFETs), as it determines the device performance. This dissertation contains investigations of the deposition and interface of binary oxide films on GaAs(100) and InAs(100) surfaces aiming at understanding the removal of the surface native oxides during certain atomic layer deposition (ALD) processes. To accomplish that, two complementary experimental approaches have been used. Initially, films were deposited in a conventional ALD reactor and characterized ex situ using spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The systems examined were Ta2O 5 on GaAs(100) surfaces from pentakis(dimethylamino) tantalum (Ta(N(CH 3)2)5, PDMAT) and TiO2 on GaAs(100) and InAs(100) surfaces from tetrakis(dimethylamino) titanium (Ti(N(CH 3)2)4, TDMAT). For these systems, deposition at the optimal ALD temperature resulted in practically sharp interfaces. Indium oxides were found to diffuse through ~ 6 nm of TiO2 film and accumulate on the topmost film layer. For the ALD of Ta2O5 on GaAs(100) surfaces, native oxide removal was enhanced at deposition temperatures above the ALD window; for ALD of TiO2 on both GaAs(100) and InAs(100) surfaces, native oxide removal was enhanced as the deposition temperatures increased up to 250 A°C, while oxidation of the interface was observed for deposition above 300 A°C due to the formation of noncontinuous films. To elucidate the surface reactions occurring during the deposition, an in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy apparatus was constructed and used to investigate the surface reactions during the ALD of TiO2 and HfO2 on GaAs(100) surfaces. The

  14. Low temperature plasma enhanced CVD epitaxial growth of silicon on GaAs: a new paradigm for III-V/Si integration

    PubMed Central

    Cariou, Romain; Chen, Wanghua; Maurice, Jean-Luc; Yu, Jingwen; Patriarche, Gilles; Mauguin, Olivia; Largeau, Ludovic; Decobert, Jean; Roca i Cabarrocas, Pere

    2016-01-01

    The integration of III-V semiconductors with silicon is a key issue for photonics, microelectronics and photovoltaics. With the standard approach, namely the epitaxial growth of III-V on silicon, thick and complex buffer layers are required to limit the crystalline defects caused by the interface polarity issues, the thermal expansion, and lattice mismatches. To overcome these problems, we have developed a reverse and innovative approach to combine III-V and silicon: the straightforward epitaxial growth of silicon on GaAs at low temperature by plasma enhanced CVD (PECVD). Indeed we show that both GaAs surface cleaning by SiF4 plasma and subsequent epitaxial growth from SiH4/H2 precursors can be achieved at 175 °C. The GaAs native oxide etching is monitored with in-situ spectroscopic ellipsometry and Raman spectroscopy is used to assess the epitaxial silicon quality. We found that SiH4 dilution in hydrogen during deposition controls the layer structure: the epitaxial growth happens for deposition conditions at the transition between the microcrystalline and amorphous growth regimes. SIMS and STEM-HAADF bring evidences for the interface chemical sharpness. Together, TEM and XRD analysis demonstrate that PECVD enables the growth of high quality relaxed single crystal silicon on GaAs. PMID:27166163

  15. Liquid phase epitaxy of binary III-V nanocrystals in thin Si layers triggered by ion implantation and flash lamp annealing

    NASA Astrophysics Data System (ADS)

    Wutzler, Rene; Rebohle, Lars; Prucnal, Slawomir; Bregolin, Felipe L.; Hübner, Rene; Voelskow, Matthias; Helm, Manfred; Skorupa, Wolfgang

    2015-05-01

    The integration of III-V compound semiconductors in Si is a crucial step towards faster and smaller devices in future technologies. In this work, we investigate the formation process of III-V compound semiconductor nanocrystals, namely, GaAs, GaSb, and InP, by ion implantation and sub-second flash lamp annealing in a SiO2/Si/SiO2 layer stack on Si grown by plasma-enhanced chemical vapor deposition. Raman spectroscopy, Rutherford Backscattering spectrometry, and transmission electron microscopy were performed to identify the structural and optical properties of these structures. Raman spectra of the nanocomposites show typical phonon modes of the compound semiconductors. The formation process of the III-V compounds is found to be based on liquid phase epitaxy, and the model is extended to the case of an amorphous matrix without an epitaxial template from a Si substrate. It is shown that the particular segregation and diffusion coefficients of the implanted group-III and group-V ions in molten Si significantly determine the final appearance of the nanostructure and thus their suitability for potential applications.

  16. Low temperature plasma enhanced CVD epitaxial growth of silicon on GaAs: a new paradigm for III-V/Si integration

    NASA Astrophysics Data System (ADS)

    Cariou, Romain; Chen, Wanghua; Maurice, Jean-Luc; Yu, Jingwen; Patriarche, Gilles; Mauguin, Olivia; Largeau, Ludovic; Decobert, Jean; Roca I Cabarrocas, Pere

    2016-05-01

    The integration of III-V semiconductors with silicon is a key issue for photonics, microelectronics and photovoltaics. With the standard approach, namely the epitaxial growth of III-V on silicon, thick and complex buffer layers are required to limit the crystalline defects caused by the interface polarity issues, the thermal expansion, and lattice mismatches. To overcome these problems, we have developed a reverse and innovative approach to combine III-V and silicon: the straightforward epitaxial growth of silicon on GaAs at low temperature by plasma enhanced CVD (PECVD). Indeed we show that both GaAs surface cleaning by SiF4 plasma and subsequent epitaxial growth from SiH4/H2 precursors can be achieved at 175 °C. The GaAs native oxide etching is monitored with in-situ spectroscopic ellipsometry and Raman spectroscopy is used to assess the epitaxial silicon quality. We found that SiH4 dilution in hydrogen during deposition controls the layer structure: the epitaxial growth happens for deposition conditions at the transition between the microcrystalline and amorphous growth regimes. SIMS and STEM-HAADF bring evidences for the interface chemical sharpness. Together, TEM and XRD analysis demonstrate that PECVD enables the growth of high quality relaxed single crystal silicon on GaAs.

  17. Increased bismuth concentration in MBE GaAs{sub 1−x}Bi{sub x} films by oscillating III/V flux ratio during growth

    SciTech Connect

    Wood, Adam W. Babcock, Susan E.; Li, Jincheng; Brown, April S.

    2015-05-15

    The authors have examined bismuth concentration profiles in GaAs{sub 1−x}Bi{sub x} films grown by molecular beam epitaxy using high angle annular dark field imaging (Z-contrast imaging) in an aberration-corrected scanning transmission electron microscope in conjunction with x-ray diffraction. Samples were grown with a gradient in each of the component fluxes, and therefore, the III/V ratio across the substrate. Rotating the sample during growth exposed the growth surface to an oscillating III/V flux ratio. Sinusoidal [Bi] profiles resulted in the growth direction, the wavelength and number of which were consistent with the growth rate and the rate of substrate rotation. However, the magnitude of [Bi] in the observed fluctuations was greater than the maximum [Bi] achieved using the same Bi flux and Ga/As flux ratios in steady-state conditions on a stationary substrate, suggesting that varying the III/V flux ratio during growth promotes the incorporation of Bi in GaAs{sub 1−x}Bi{sub x} films. A proposed qualitative model for how this enhancement might occur hypothesizes a critical role for alternating growth and shrinkage of Ga-Bi predroplet clusters on the surface as the growing material is rotated through Ga-rich and As-rich flux compositions.

  18. The Dependence of Electrical Properties on Miscut Orientation in Direct Bonded III-V Solar Cell Layers

    NASA Astrophysics Data System (ADS)

    Seal, Mark

    interface morphology. No interfacial layer is present in InP//InP structures before or after rapid thermal processing. It is observed that regions adjacent to the interface undergo a process of atomic redistribution and recrystallize into the same lattice arrangement as the bulk semiconductor. GaAs//InP interfaces are observed to contain regions direct substrate contact with oxide inclusions in between after rapid thermal processing, consistent with previous work on GaAs//GaAs interfaces. It is concluded that for III-V direct wafer bonded heterostructures, interface conductivity is a function of both the relative misorientation between the (001) surfaces and the material pair. The significance of this study is that the additional variable of lattice mismatch does not degrade electrical conductivity through GaAs//InP interfaces. This is significant for applications where heterostructure interface conduction must be controlled, such as the direct bonding of III-V wafers for photovoltaic applications.

  19. Optimization and Characterization of Indium Arsenide Quantum Dots for Application in III-V Material Solar Cells

    NASA Astrophysics Data System (ADS)

    Podell, Adam P.

    In this work, InAs quantum dots grown by organometallic vapor-phase epitaxy (OMVPE) are investigated for application in III - V material solar cells. The first focus is on the opti- mization of growth parameters to produce high densities of uniform defect-free quantum dots via growth on 2" vicinal GaAs substrates. Parameters studied are InAs coverage, V/III ratio and growth rate. QDs are grown by the Stranski-Krastanov (SK) growth mode on (100) GaAs substrates misoriented toward (110) or (111) planes with various degrees of misorientation from 0° to 6°. Atomic force microscopy results indicated that as misorientation angle increased toward(110),critical thickness for quantum dot formation increased with theta c =1.8ML,1.9ML and 2.0 ML corresponding to 0°, 2° and 6°, respectively. Results for quantum dots grown on (111) misoriented substrates indicated, on average, that higher densities of quantum dots were achieved, compared with similar growths on substrates misoriented toward (110). Most notably, a stable average number density of 8 x 1010cm -2 was observed over a range of growth rates of 0.1ML/s - 0.4ML/s on (111) misoriented substrates compared with a decreasing number density as low as 2.85 x 1010cm -2 corresponding to a growth rate of 0.4ML/s grown on (110) misoriented substrates. p-i-n solar cell devices with a 10-layer quantum dot super- lattice imbedded in the i-region were also grown on (100) GaAs substrates misoriented 0°, 2° and 6° toward (110) as well as a set of devices grown on substrates misoriented toward (111). Device results showed a 1.0mA/cm2 enhancement to the short-circuit current for a v 2° misoriented device with 2.2 ML InAs coverage per quantum dot layer. Spectral response measurements were performed and integrated spectral response showed sub-GaAs bandgap short-circuit contribution which increased with increasing InAs coverage in the quantum dot layers from 0.04mA/cm2/ML, 0.28mA/cm2/ ML and 0.19mA/cm2/ML corresponding to 0°, 2

  20. A thermodynamic analysis of native point defect and dopant solubilities in zinc-blende III-V semiconductors

    SciTech Connect

    Hurle, D. T. J.

    2010-06-15

    A thermodynamic model is used to analyze available experimental data relevant to point defects in the binary zinc-blende III-V compounds (Ga,In)-(P,As,Sb). The important point defects and their complexes in each of the materials are identified and included in the model. Essentially all of the available experimental data on dopant solubility, crystal density, and lattice parameter of melt and solution grown crystals and epilayers are reproduced by the model. It extends an earlier study [Hurle, J. Appl. Phys. 85, 6957 (1999)] devoted solely to GaAs. Values for the enthalpy and entropy of formation of both native and dopant related point defects are obtained by fitting to experimental data. In undoped material, vacancies, and interstitials on the Group V sublattice dominate in the vicinity of the melting point (MP) in both the phosphides and arsenides, whereas, in the antimonides, vacancies on both sublattices dominate. The calculated concentrations of the native point defects are used to construct the solidus curves of all the compounds. The charged native point defect concentrations at the MP in four of the six materials are significantly higher than their intrinsic carrier concentrations. Thus the usually assumed high temperature 'intrinsic' electroneutrality condition for undoped material (n=p) is not valid for these materials. In GaSb, the Ga{sub Sb} antisite defect appears to be grown-in from the melt. This contrasts with the As{sub Ga} defect in GaAs for which the concentration grown-in at the MP is negligibly small. Compensation of donor-doped material by donor-Group III vacancy complexes is shown to exist in all the compounds except InP where Group VI doped crystals are uncompensated and in InSb where there is a lack of experimental data. The annealing effects in n{sup +} GaAs, including lattice superdilation, which were shown in the earlier paper to be due to Group III vacancy undersaturation during cooling, are found to be present also in GaSb and In

  1. A thermodynamic analysis of native point defect and dopant solubilities in zinc-blende III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Hurle, D. T. J.

    2010-06-01

    A thermodynamic model is used to analyze available experimental data relevant to point defects in the binary zinc-blende III-V compounds (Ga,In)-(P,As,Sb). The important point defects and their complexes in each of the materials are identified and included in the model. Essentially all of the available experimental data on dopant solubility, crystal density, and lattice parameter of melt and solution grown crystals and epilayers are reproduced by the model. It extends an earlier study [Hurle, J. Appl. Phys. 85, 6957 (1999)] devoted solely to GaAs. Values for the enthalpy and entropy of formation of both native and dopant related point defects are obtained by fitting to experimental data. In undoped material, vacancies, and interstitials on the Group V sublattice dominate in the vicinity of the melting point (MP) in both the phosphides and arsenides, whereas, in the antimonides, vacancies on both sublattices dominate. The calculated concentrations of the native point defects are used to construct the solidus curves of all the compounds. The charged native point defect concentrations at the MP in four of the six materials are significantly higher than their intrinsic carrier concentrations. Thus the usually assumed high temperature "intrinsic" electroneutrality condition for undoped material (n=p) is not valid for these materials. In GaSb, the GaSb antisite defect appears to be grown-in from the melt. This contrasts with the AsGa defect in GaAs for which the concentration grown-in at the MP is negligibly small. Compensation of donor-doped material by donor-Group III vacancy complexes is shown to exist in all the compounds except InP where Group VI doped crystals are uncompensated and in InSb where there is a lack of experimental data. The annealing effects in n+ GaAs, including lattice superdilation, which were shown in the earlier paper to be due to Group III vacancy undersaturation during cooling, are found to be present also in GaSb and InAs. Results for native

  2. Replacement of hydrides by TBAs and TBP for the growth of various III V materials in production scale MOVPE reactors

    NASA Astrophysics Data System (ADS)

    Beccard, R.; Lengeling, G.; Schmitz, D.; Gigase, Y.; Jürgensen, H.

    1997-01-01

    Besides the standard group V precursors AsH 3 and PH 3, so-called alternative precursors like TBAs and TBP (tertiary-butyl-arsine and tertiary-butyl-phosphine) are more and more important in today's MOVPE processes. A lot of publications have demonstrated that these precursors can be successfully used for the growth of different III-V materials. In this study we want to demonstrate that TBAs and TBP can be used as the group V precursor in a complete family of production scale reactors. It is shown that these precursors can be used for the growth of InP-based as well as for GaAs-based materials. The reactors that have been employed are medium scale reactors (AIX 200/4; 1 × 2 inch, 3 or 4 inch or 3 × 2 inch capability) and large scale Planetary Reactors®, in particular the AIX 2400 system (15 × 2 inch or 5 × 4 inch). Materials that have been grown are (Al)GaInP on GaAs and GaInAsP on InP. The lower cracking energy of these precursors compared to PH 3 and AsH 3 allows one to use lower growth temperatures and lower {V}/{III} ratios, particularly in combination with the high cracking efficiencies of the used reactors. For the growth of GaInAsP on InP, the consumption of TBP and TBAs is up to 8 times lower than using PH 3 and AsH 3. GaInP on GaAs could be grown with a {V}/{III} ratio as low as 25 in a Planetary Reactor®. Good crystalline quality is demonstrated by DCXD (e.g. for GaInP: FWHM = 35 arcsec, substrate 32 arcsec). PL intensity and growth rate are not affected by using the alternative precursors. The compositional uniformity is similar to layers grown with arsine and phosphine (e.g. 1.5 nm uniformity for GaInAsP ( λ = 1.5 μm) on 2 inch; approximately 1 nm uniformity for GaInP) [1,2]. The purity of the grown layers depends mainly on the quality of the TBP and TBAs. Using high purity TBP, InP revealed background carrier concentration in the mid 10 14 cm -3 regime. Our investigation shows that TBP and TBAs can replace phosphine and arsine in state of the

  3. Nanostructures produced by phase-separation during growth of (III-V).sub.1-x(IV.sub.2).sub.x alloys

    DOEpatents

    Norman, Andrew G.; Olson, Jerry M.

    2007-06-12

    Nanostructures (18) and methods for production thereof by phase separation during metal organic vapor-phase epitaxy (MOVPE). An embodiment of one of the methods may comprise providing a growth surface in a reaction chamber and introducing a first mixture of precursor materials into the reaction chamber to form a buffer layer (12) thereon. A second mixture of precursor materials may be provided into the reaction chamber to form an active region (14) on the buffer layer (12), wherein the nanostructure (18) is embedded in a matrix (16) in the active region (14). Additional steps are also disclosed for preparing the nanostructure (18) product for various applications.

  4. Arsenic (III, V), indium (III), and gallium (III) toxicity to zebrafish embryos using a high-throughput multi-endpoint in vivo developmental and behavioral assay.

    PubMed

    Olivares, Christopher I; Field, Jim A; Simonich, Michael; Tanguay, Robert L; Sierra-Alvarez, Reyes

    2016-04-01

    Gallium arsenide (GaAs), indium gallium arsenide (InGaAs) and other III/V materials are finding increasing application in microelectronic components. The rising demand for III/V-based products is leading to increasing generation of effluents containing ionic species of gallium, indium, and arsenic. The ecotoxicological hazard potential of these streams is unknown. While the toxicology of arsenic is comprehensive, much less is known about the effects of In(III) and Ga(III). The embryonic zebrafish was evaluated for mortality, developmental abnormalities, and photomotor response (PMR) behavior changes associated with exposure to As(III), As(V), Ga(III), and In(III). The As(III) lowest observable effect level (LOEL) for mortality was 500 μM at 24 and 120 h post fertilization (hpf). As(V) exposure was associated with significant mortality at 63 μM. The Ga(III)-citrate LOEL was 113 μM at 24 and 120 hpf. There was no association of significant mortality over the tested range of In(III)-citrate (56-900 μM) or sodium citrate (213-3400 μM) exposures. Only As(V) resulted in significant developmental abnormalities with LOEL of 500 μM. Removal of the chorion prior to As(III) and As(V) exposure was associated with increased incidence of mortality and developmental abnormality suggesting that the chorion may normally attenuate mass uptake of these metals by the embryo. Finally, As(III), As(V), and In(III) caused PMR hypoactivity (49-69% of control PMR) at 900-1000 μM. Overall, our results represent the first characterization of multidimensional toxicity effects of III/V ions in zebrafish embryos helping to fill a significant knowledge gap, particularly in Ga(III) and In(III) toxicology.

  5. Beyond CMOS: heterogeneous integration of III-V devices, RF MEMS and other dissimilar materials/devices with Si CMOS to create intelligent microsystems.

    PubMed

    Kazior, Thomas E

    2014-03-28

    Advances in silicon technology continue to revolutionize micro-/nano-electronics. However, Si cannot do everything, and devices/components based on other materials systems are required. What is the best way to integrate these dissimilar materials and to enhance the capabilities of Si, thereby continuing the micro-/nano-electronics revolution? In this paper, I review different approaches to heterogeneously integrate dissimilar materials with Si complementary metal oxide semiconductor (CMOS) technology. In particular, I summarize results on the successful integration of III-V electronic devices (InP heterojunction bipolar transistors (HBTs) and GaN high-electron-mobility transistors (HEMTs)) with Si CMOS on a common silicon-based wafer using an integration/fabrication process similar to a SiGe BiCMOS process (BiCMOS integrates bipolar junction and CMOS transistors). Our III-V BiCMOS process has been scaled to 200 mm diameter wafers for integration with scaled CMOS and used to fabricate radio-frequency (RF) and mixed signals circuits with on-chip digital control/calibration. I also show that RF microelectromechanical systems (MEMS) can be integrated onto this platform to create tunable or reconfigurable circuits. Thus, heterogeneous integration of III-V devices, MEMS and other dissimilar materials with Si CMOS enables a new class of high-performance integrated circuits that enhance the capabilities of existing systems, enable new circuit architectures and facilitate the continued proliferation of low-cost micro-/nano-electronics for a wide range of applications.

  6. Ultralow-power all-optical wavelength conversion in a silicon-on-insulator waveguide based on a heterogeneously integrated III-V microdisk laser

    NASA Astrophysics Data System (ADS)

    Liu, Liu; Van Campenhout, Joris; Roelkens, Günther; Van Thourhout, Dries; Rojo-Romeo, Pedro; Regreny, Philippe; Seassal, Christian; Fédéli, Jean-Marc; Baets, Roel

    2008-08-01

    Ultralow-power all-optical wavelength conversion is presented for a silicon-on-insulator wire waveguide with a heterogeneously integrated III-V microdisk laser. The principle relies on the suppression of natural lasing from the microdisk laser by an external injection. No probe beam is needed in this configuration. Static wavelength conversion with a control power of 6.4 μW or even lower is achieved. The resonance and gain provided by the microdisk cavity are at the origin of such low control power. Dynamically, wavelength conversion using a 5 Gbps non-return-to-zero bit sequence is demonstrated in the proposed device.

  7. Detection of soft X-rays with NEA III-V photocathodes. [Negative Electron Affinity X-ray detector for astronomy

    NASA Technical Reports Server (NTRS)

    Bardas, D.; Kellogg, E.; Murray, S.; Enck, R., Jr.

    1978-01-01

    A description is presented of the results of tests on an X-ray photomultiplier containing a negative electron affinity (NEA) photocathode. This device makes it possible to investigate the response of the NEA photocathode to X-rays of various energies. The obtained data provide a basis for the determination of the photoelectron yield and energy resolution of the considered photocathode as a function of energy in the range from 0.8 to 3 keV. The investigation demonstrates the feasibility of using an NEA III-V photocathode for the detection of soft X-rays.

  8. Electronic structure of and quantum size effect in III-V and II-VI semiconducting nanocrystals using a realistic tight binding approach

    NASA Astrophysics Data System (ADS)

    Viswanatha, Ranjani; Sapra, Sameer; Saha-Dasgupta, Tanusri; Sarma, D. D.

    2005-07-01

    We analyze the electronic structure of group III-V semiconductors obtained within full potential linearized augmented plane wave (FP-LAPW) method and arrive at a realistic and minimal tight-binding model, parametrized to provide an accurate description of both valence and conduction bands. It is shown that the cation sp3 - anion sp3d5 basis along with the next nearest neighbor model for hopping interactions is sufficient to describe the electronic structure of these systems over a wide energy range, obviating the use of any fictitious s* orbital, employed previously. Similar analyses were also performed for the II-VI semiconductors, using the more accurate FP-LAPW method compared to previous approaches, in order to enhance reliability of the parameter values. Using these parameters, we calculate the electronic structure of III-V and II-VI nanocrystals in real space with sizes ranging up to about 7nm in diameter, establishing a quantitatively accurate description of the bandgap variation with sizes for the various nanocrystals by comparing with available experimental results from the literature.

  9. The recombination velocity at III-V compound heterojunctions with applications to Al (x) Ga(1-x)As-GaAs(1-y)Sb(y)

    NASA Technical Reports Server (NTRS)

    Kim, J. S.

    1978-01-01

    Interface recombination velocity in AlxGa1-xAs-GaAs and A10.85 Ga0.15As-GaAs1-ySby heterojunction systems was studied as a function of lattice mismatch. The results are applied to the design of highly efficient III-V heterojunction solar cells. A horizontal liquid-phase epitaxial growth system was used to prepare p-p-p and p-p-n double heterojunction test samples with specified values of x and y. Samples were grown at each composition, with different GaAs and GaAsSb layer thicknesses. A method was developed to obtain the lattice mismatch and lattice constants in mixed single crystals grown on (100) and (111)B oriented GaAs substrates.

  10. New III-V cell design approaches for very high efficiency. Annual subcontract report, 1 August 1990--31 July 1991

    SciTech Connect

    Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; O`Bradovich, G.J.; Young, M.P.

    1993-01-01

    This report describes progress during the first year of a three-year project. The objective of the research is to examine new design approaches for achieving very high conversion efficiencies. The program is divided into two areas. The first centers on exploring new thin-film approaches specifically designed for III-V semiconductors. The second area centers on exploring design approaches for achieving high conversion efficiencies without requiring extremely high quality material. Research activities consisted of an experimental study of minority carrier recombination in n-type, metal-organic chemical vapor deposition (MOCVD)-deposited GaAs, an assessment of the minority carrier lifetimes in n-GaAs grown by molecular beam epitaxy, and developing a high-efficiency cell fabrication process.

  11. Heterogeneously integrated III-V-on-silicon 2.3x μm distributed feedback lasers based on a type-II active region

    NASA Astrophysics Data System (ADS)

    Wang, Ruijun; Sprengel, Stephan; Malik, Aditya; Vasiliev, Anton; Boehm, Gerhard; Baets, Roel; Amann, Markus-Christian; Roelkens, Gunther

    2016-11-01

    We report on 2.3x μm wavelength InP-based type-II distributed feedback (DFB) lasers heterogeneously integrated on a silicon photonics integrated circuit. In the devices, a III-V epitaxial layer stack with a "W"-shaped InGaAs/GaAsSb multi-quantum-well active region is adhesively bonded to the first-order silicon DFB gratings. Single mode laser emission coupled to a single mode silicon waveguide with a side mode suppression ratio of 40 dB is obtained. In continuous-wave regime, the 2.32 μm laser operates close to room temperature (above 15 °C) and emits more than 1 mW output power with a threshold current density of 1.8 kA/cm2 at 5 °C. A tunable diode laser absorption measurement of CO is demonstrated using this source.

  12. New III-V cell design approaches for very high efficiency. Annual subcontract report, 1 August 1991--31 July 1992

    SciTech Connect

    Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; Patkar, M.P.; Young, M.P.

    1993-04-01

    This report describes to examine new solar cell desip approaches for achieving very high conversion efficiencies. The program consists of two elements. The first centers on exploring new thin-film approaches specifically designed for M-III semiconductors. Substantial efficiency gains may be possible by employing light trapping techniques to confine the incident photons, as well as the photons emitted by radiative recombination. The thin-film approach is a promising route for achieving substantial performance improvements in the already high-efficiency, single-junction, III-V cell. The second element of the research involves exploring desip approaches for achieving high conversion efficiencies without requiring extremely high-quality material. This work has applications to multiple-junction cells, for which the selection of a component cell often involves a compromise between optimum band pp and optimum material quality. It could also be a benefit manufacturing environment by making the cell`s efficiency less dependent on materialquality.

  13. Calculating Effect of Point Defects on Optical Absorption Spectra of III-V Semiconductor Superlattices Based on (8x8) k-dot-p Band Structures

    NASA Astrophysics Data System (ADS)

    Huang, Danhong; Iurov, Andrii; Gumbs, Godfrey; Cardimona, David; Krishna, Sanjay

    For a superlattice which is composed of layered zinc-blende structure III-V semiconductor materials, its realistic anisotropic band structures around the Gamma-point are calculated by using the (8x8)k-dot-p method with the inclusion of the self-consistent Hartree potential and the spin-orbit coupling. By including the many-body screening effect, the obtained band structures are further employed to calculate the optical absorption coefficient which is associated with the interband electron transitions. As a result of a reduced quasiparticle lifetime due to scattering with point defects in the system, the self-consistent vertex correction to the optical response function is also calculated with the help of the second-order Born approximation.

  14. Benchmarks of a III-V TFET technology platform against the 10-nm CMOS FinFET technology node considering basic arithmetic circuits

    NASA Astrophysics Data System (ADS)

    Strangio, S.; Palestri, P.; Lanuzza, M.; Esseni, D.; Crupi, F.; Selmi, L.

    2017-02-01

    In this work, a benchmark for low-power digital applications of a III-V TFET technology platform against a conventional CMOS FinFET technology node is proposed. The analysis focuses on full-adder circuits, which are commonly identified as representative of the digital logic environment. 28T and 24T topologies, implemented in complementary-logic and transmission-gate logic, respectively, are investigated. Transient simulations are performed with a purpose-built test-bench on each single-bit full adder solution. The extracted delays and energy characteristics are post-processed and translated into figures-of-merit for multi-bit ripple-carry-adders. Trends related to the different full-adder implementations (for the same device technology platform) and to the different technology platforms (for the same full-adder topology) are presented and discussed.

  15. Effect of low temperature anneals and nonthermal treatments on the properties of gap fill oxides used in SiGe and III-V devices

    NASA Astrophysics Data System (ADS)

    Ryan, E. Todd; Morin, Pierre; Madan, Anita; Mehta, Sanjay

    2016-07-01

    Silicon dioxide is used to electrically isolate CMOS devices such as fin field effect transistors by filling gaps between the devices (also known as shallow trench isolation). The gap fill oxide typically requires a high temperature anneal in excess of 1000 °C to achieve adequate electrical properties and oxide densification to make the oxide compatible with subsequent fabrication steps such as fin reveal etch. However, the transition from Si-based devices to high mobility channel materials such as SiGe and III-V semiconductors imposes more severe thermal limitations on the processes used for device fabrication, including gap fill oxide annealing. This study provides a framework to quantify and model the effect of anneal temperature and time on the densification of a flowable silicon dioxide as measured by wet etch rate. The experimental wet etch rates allowed the determination of the activation energy and anneal time dependence for oxide densification. Dopant and self-diffusion can degrade the channel material above a critical temperature. We present a model of self-diffusion of Ge and Si in SiGe materials. Together these data allowed us to map the thermal process space for acceptable oxide wet etch rate and self-diffusion. The methodology is also applicable to III-V devices, which require even lower thermal budget. The results highlight the need for nonthermal oxide densification methods such as ultraviolet (UV) and plasma treatments. We demonstrate that several plasma treatments, in place of high temperature annealing, improved the properties of flowable oxide. In addition, UV curing prior to thermal annealing enables acceptable densification with dramatically reduced anneal temperature.

  16. Effects of brining on the corrosion of ZVI and its subsequent As(III/V) and Se(IV/VI) removal from water.

    PubMed

    Yang, Zhe; Xu, Hui; Shan, Chao; Jiang, Zhao; Pan, Bingcai

    2017-03-01

    Zero-valent iron (ZVI) has been extensively applied in water remediation, and most of the ZVI materials employed in practical applications are iron scraps, which have usually been corroded to certain extent under different conditions. In this study, the effects of brining with six solutions (NaCl, Na2SO4, NaHCO3, Na2SiO3, NH4Cl, and NaH2PO4) on the corrosion of ZVI and its performance in the removal of As(III/V)/Se(IV/VI) were systematically investigated. All the studied solutions enhanced the corrosion of ZVI except for Na2SiO3, and the degrees of corrosion followed the order of NH4Cl > NaH2PO4 > Na2SO4 > NaCl > NaHCO3 > H2O > Na2SiO3. The corrosion products derived from ZVI were identified by SEM and XRD, and the dominant corrosion products varied with the type of brine solution. The positive correlation between the degree of ZVI corrosion and As(III/V)/Se(IV/VI) removal by the pre-corroded ZVI (pcZVI) was verified. In addition, As and Se removal by pcZVI was realized via a comprehensive process including adsorption and reduction, as further supported by the XPS analysis. We believe this study will shed new light upon the selection of iron materials pre-corroded under different saline conditions for practical water remediation.

  17. Structural properties of bismuth-bearing semiconductor alloys

    NASA Technical Reports Server (NTRS)

    Berding, M. A.; Sher, A.; Chen, A.-B.; Miller, W. E.

    1988-01-01

    The structural properties of bismuth-bearing III-V semiconductor alloys InPBi, InAsBi, and InSbBi were studied theoretically. Bond energies, bond lengths, and strain coefficients were calculated for pure AlBi, GaBi, and InBi compounds and their alloys, and predictions were made for the mixing enthalpies, miscibility gaps, and critical metastable-to-stable material transition temperatures. Miscibility calculations indicate that InSbBi will be the most miscible, and the InPBi will be the the most difficult to mix. However, calculations of the hardness of the Bi compounds indicate that, once formed, the InPBi alloy will be harder than the other Bi alloys and substantially harder than the currently favored narrow-gap semiconductor HgCdTe.

  18. III-V-semiconductor-on-insulator n-channel metal-insulator-semiconductor field-effect transistors with buried Al2O3 layers and sulfur passivation: Reduction in carrier scattering at the bottom interface

    NASA Astrophysics Data System (ADS)

    Yokoyama, Masafumi; Yasuda, Tetsuji; Takagi, Hideki; Miyata, Noriyuki; Urabe, Yuji; Ishii, Hiroyuki; Yamada, Hisashi; Fukuhara, Noboru; Hata, Masahiko; Sugiyama, Masakazu; Nakano, Yoshiaki; Takenaka, Mitsuru; Takagi, Shinichi

    2010-04-01

    We have developed III-V-semiconductor-on-insulator (III-V-OI) structures on Si wafers with excellent bottom interfaces between In0.53Ga0.47As-OI channel layers and atomic-layer-deposited Al2O3 (ALD-Al2O3) buried oxides (BOXs). A surface activated bonding process and the sulfur passivation pretreatment have realized the excellent In0.53Ga0.47As-OI/ALD-Al2O3 BOX bottom interface properties. As a result, the III-V-OI n-channel metal-insulator-semiconductor field-effect transistors under the back-gate configuration showed the peak mobility of 1800 cm2/V s and the higher electron mobility than the Si universal one even in the high effective electric field range because of the reduction in the surface roughness and fixed charges.

  19. Determining the Presence of Ordering in Ternary Semiconductor Alloys Grown by Molecular Beam Epitaxy

    DTIC Science & Technology

    2013-01-01

    not usually detectable by the standard (004) x-ray diffraction (XRD) measurements typically used as a simple measurement of film quality. 15. SUBJECT...as a simple measurement of film quality. 2. Motivation and Army Interest One common example of ordering seen in many semiconductor alloys is copper...this will provide a III-V analog to direct bandgap mercury cadmium telluride (HgCdTe), with the benefits of higher quantum efficiencies (QEs) and

  20. Study of Magnetic Alloys: Critical Phenomena.

    DTIC Science & Technology

    MAGNETIC ALLOYS, TRANSPORT PROPERTIES), ELECTRICAL RESISTANCE, SEEBECK EFFECT , MAGNETIC PROPERTIES, ALUMINUM ALLOYS, COBALT ALLOYS, GADOLINIUM ALLOYS, GOLD ALLOYS, IRON ALLOYS, NICKEL ALLOYS, PALLADIUM ALLOYS, PLATINUM ALLOYS, RHODIUM ALLOYS

  1. Large-signal characterizations of DDR IMPATT devices based on group III-V semiconductors at millimeter-wave and terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Acharyya, Aritra; Mallik, Aliva; Banerjee, Debopriya; Ganguli, Suman; Das, Arindam; Dasgupta, Sudeepto; Banerjee, J. P.

    2014-08-01

    Large-signal (L-S) characterizations of double-drift region (DDR) impact avalanche transit time (IMPATT) devices based on group III-V semiconductors such as wurtzite (Wz) GaN, GaAs and InP have been carried out at both millimeter-wave (mm-wave) and terahertz (THz) frequency bands. A L-S simulation technique based on a non-sinusoidal voltage excitation (NSVE) model developed by the authors has been used to obtain the high frequency properties of the above mentioned devices. The effect of band-to-band tunneling on the L-S properties of the device at different mm-wave and THz frequencies are also investigated. Similar studies are also carried out for DDR IMPATTs based on the most popular semiconductor material, i.e. Si, for the sake of comparison. A comparative study of the devices based on conventional semiconductor materials (i.e. GaAs, InP and Si) with those based on Wz-GaN shows significantly better performance capabilities of the latter at both mm-wave and THz frequencies.

  2. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum

    PubMed Central

    Seghilani, Mohamed S.; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-01-01

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here “orbital birefringence”, based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create “orbital gain dichroism” allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications. PMID:27917885

  3. X-Ray Emission Spectra and Electronic Structures of Red Phosphorus, 3d Transition-Metal Phosphides and III V Compounds

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1995-07-01

    The P Kβ emission spectra in fluorescence from red amorphous phosphorus, 3d transition-metal phosphides TiP, CrP, FeP, Fe2P, Fe3P, CoP, Co2P, Ni5P4, Ni2P, Ni3P, Cu3P, ZnP2 (black) and Zn3P2, and the semiconducting phosphides of the III-V type, BP, AlP, GaP and InP are measured with a high-resolution two-crystal vacuum spectrometer equipped with Ge(111) crystals. The influence of the metal atoms appears distinctly on the P Kβ fluorescence emission spectra. The measured spectra are compared with available X-ray emission and XPS valence-band spectra and theoretical energy-band calculations on a common energy scale. It is shown that considerable p-d, s mixing occurs in the valence bands of the 3d transition-metal phosphides and the P 3p states mix fairly with the P 3s states in the valence bands of red phosphorus, Gap and InP

  4. Systematic defect donor levels in III-V and II-VI semiconductors revealed by hybrid functional density-functional theory

    NASA Astrophysics Data System (ADS)

    Petretto, Guido; Bruneval, Fabien

    2015-12-01

    The identification of defect levels from photoluminescence spectroscopy is a useful but challenging task. Density-functional theory (DFT) is a highly valuable tool to this aim. However, the semilocal approximations of DFT that are affected by a band gap underestimation are not reliable to evaluate defect properties, such as charge transition levels. It is now established that hybrid functional approximations to DFT improve the defect description in semiconductors. Here we demonstrate that the use of hybrid functionals systematically stabilizes donor defect states in the lower part of the band gap for many defects, impurities or vacancies, in III-V and in II-VI semiconductors, even though these defects are usually considered as acceptors. These donor defect states are a very general feature and, to the best of our knowledge, have been overlooked in previous studies. The states we identify here may challenge the older assignments to photoluminescent peaks. Though appealing to screen quickly through the possible stable charge states of a defect, semilocal approximations should not be trusted for that purpose.

  5. Electrochemically synthesized broadband antireflective and hydrophobic GaOOH nanopillars for III-V InGaP/GaAs/Ge triple-junction solar cell applications.

    PubMed

    Leem, Jung Woo; Lee, Hee Kwan; Jun, Dong-Hwan; Heo, Jonggon; Park, Won-Kyu; Park, Jin-Hong; Yu, Jae Su

    2014-03-10

    We report the efficiency enhancement of III-V InGaP/GaAs/ Ge triple-junction (TJ) solar cells using a novel structure, i.e., vertically-oriented gallium oxide hydroxide (GaOOH) nanopillars (NPs), as an antireflection coating. The optical reflectance properties of rhombus-shaped GaOOH NPs, which were synthesized by a simple, low-cost, and large-scalable electrochemical deposition method, were investigated, together with a theoretical analysis using the rigorous coupled-wave analysis method. For the GaOOH NPs, the solar weighted reflectance of ~8.5% was obtained over a wide wavelength range of 300-1800 nm and their surfaces exhibited a high water contact angle of ~130° (i.e., hydrophobicity). To simply demonstrate the feasibility of device applications, the GaOOH NPs were incorporated into a test-grown InGaP/GaAs/Ge TJ solar cell structure. For the InGaP/GaAs/Ge TJ solar cell with broadband antireflective GaOOH NPs, the conversion efficiency (η) of ~16.47% was obtained, indicating an increased efficiency by 3.47% compared to the bare solar cell (i.e., η~13%).

  6. Theoretical modeling and optimization of III-V GaInP/GaAs/Ge monolithic triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Leem, Jung Woo; Yu, Jae Su; Kim, Jong Nam; Noh, Sam Kyu

    2014-05-01

    We design and optimize monolithic III-V GaInP/GaAs/Ge triple-junction (TJ) solar cells by using a commercial software Silvaco ATLAS simulator to obtain the maximum short-circuit current density J sc . The maximum J sc , which is a current matching value between the GaInP top and GaAs middle subcells, can be determined by varying the base thicknesses of the GaInP top and GaAs middle subcells. From the numerical simulation results, a matched maximum J sc value of 13.92 mA/cm2 is obtained at base thicknesses of 0.57 μm and 3 μm for the GaInP top and GaAs middle subcells, respectively, under 1-sun air mass 1.5 global spectrum illumination, leading to a high power conversion efficiency of 30.72%. The open-circuit voltage and the fill factor are 2.55 V and 86.55%, respectively. For the optimized cell structure, the external quantum efficiency and the photogeneration rate distributions are also investigated. To obtain efficient antireflection coatings (ARCs), we perform optical reflectance calculations by using a rigorous coupled-wave analysis method. For this, a silicon oxide/titanium oxide double-layer is used as an ARC on the TJ solar cell.

  7. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum

    NASA Astrophysics Data System (ADS)

    Seghilani, Mohamed S.; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-12-01

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here “orbital birefringence”, based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create “orbital gain dichroism” allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications.

  8. Optically detected carrier transport in III/V semiconductor QW structures: experiments, model calculations and applications in fast 1.55 µm laser devices

    NASA Astrophysics Data System (ADS)

    Hillmer, H.; Marcinkevičius, S.

    1998-01-01

    This paper reviews optically detected carrier dynamics in III/V semiconductor quantum well (QW) heterostructures perpendicular to the interfaces. Photoluminescence emissions originating from different semiconductor layers are recorded in a time-resolved way to monitor the carrier dynamics between these layers. The experimental methods presented provide a very high spatial and temporal resolution, partly even in the nanometer and sub-picosecond ranges, respectively. Model calculations based on a self-consistent solution of the continuity equation, the Poisson equation and rate-equation(s) are used to evaluate the experimental data. It will be demonstrated that experiments using several specially tailored semiconductor heterostructures enable the following individual dynamic effects to be studied and separated: transport in extended unquantized layers, capture into the QWs, relaxation in the QWs, tunneling between the QWs and thermal re-emission from the QWs. It will be shown that several basic physical effects have to be studied and understood before modern high-speed semiconductor laser devices can be designed and implemented. By adding levels of increasing complexity, this review starts from simple basic structures to finally approach real laser structures in a sequence of consecutive steps. AlGaInAs and GaInAsP heterostructures are compared with respect to interwell transfer efficiencies and problems in technological implementation. This review proceeds from basic research on carrier dynamics to applications in high-speed laser devices. Throughout the review an overview of the experimental and theoretical literature is given.

  9. A comprehensive study of the magnetic, structural, and transport properties of the III-V ferromagnetic semiconductor InMnP

    SciTech Connect

    Khalid, M.; Hübner, R.; Baehtz, C.; Skorupa, W.; Zhou, Shengqiang; Gao, Kun; Helm, M.; Weschke, E.; Gordan, O.; Salvan, G.; Zahn, D. R. T.

    2015-01-28

    The manganese induced magnetic, electrical, and structural modification in InMnP epilayers, prepared by Mn ion implantation and pulsed laser annealing, are investigated in the following work. All samples exhibit clear hysteresis loops and strong spin polarization at the Fermi level. The degree of magnetization, the Curie temperature, and the spin polarization depend on the Mn concentration. The bright-field transmission electron micrographs show that InP samples become almost amorphous after Mn implantation but recrystallize after pulsed laser annealing. We did not observe an insulator-metal transition in InMnP up to a Mn concentration of 5 at. %. Instead all InMnP samples show insulating characteristics up to the lowest measured temperature. Magnetoresistance results obtained at low temperatures support the hopping conduction mechanism in InMnP. We find that the Mn impurity band remains detached from the valence band in InMnP up to 5 at. % Mn doping. Our findings indicate that the local environment of Mn ions in InP is similar to GaMnAs, GaMnP, and InMnAs; however, the electrical properties of these Mn implanted III-V compounds are different. This is one of the consequences of the different Mn binding energy in these compounds.

  10. Vortex Laser based on III-V semiconductor metasurface: direct generation of coherent Laguerre-Gauss modes carrying controlled orbital angular momentum.

    PubMed

    Seghilani, Mohamed S; Myara, Mikhael; Sellahi, Mohamed; Legratiet, Luc; Sagnes, Isabelle; Beaudoin, Grégoire; Lalanne, Philippe; Garnache, Arnaud

    2016-12-05

    The generation of a coherent state, supporting a large photon number, with controlled orbital-angular-momentum L = ħl (of charge l per photon) presents both fundamental and technological challenges: we demonstrate a surface-emitting laser, based on III-V semiconductor technology with an integrated metasurface, generating vortex-like coherent state in the Laguerre-Gauss basis. We use a first order phase perturbation to lift orbital degeneracy of wavefunctions, by introducing a weak anisotropy called here "orbital birefringence", based on a dielectric metasurface. The azimuthal symmetry breakdown and non-linear laser dynamics create "orbital gain dichroism" allowing selecting vortex handedness. This coherent photonic device was characterized and studied, experimentally and theoretically. It exhibits a low divergence (<1°) diffraction limited beam, emitting 49 mW output power in the near-IR at λ ≃ 1 μm, a charge l = ±1, … ±4 (>50 dB vortex purity), and single frequency operation in a stable low noise regime (0.1% rms). Such high performance laser opens the path to widespread new photonic applications.

  11. Scattering amplitudes and static atomic correction factors for the composition-sensitive 002 reflection in sphalerite ternary III-V and II-VI semiconductors.

    PubMed

    Schowalter, M; Müller, K; Rosenauer, A

    2012-01-01

    Modified atomic scattering amplitudes (MASAs), taking into account the redistribution of charge due to bonds, and the respective correction factors considering the effect of static atomic displacements were computed for the chemically sensitive 002 reflection for ternary III-V and II-VI semiconductors. MASAs were derived from computations within the density functional theory formalism. Binary eight-atom unit cells were strained according to each strain state s (thin, intermediate, thick and fully relaxed electron microscopic specimen) and each concentration (x = 0, …, 1 in 0.01 steps), where the lattice parameters for composition x in strain state s were calculated using continuum elasticity theory. The concentration dependence was derived by computing MASAs for each of these binary cells. Correction factors for static atomic displacements were computed from relaxed atom positions by generating 50 × 50 × 50 supercells using the lattice parameter of the eight-atom unit cells. Atoms were randomly distributed according to the required composition. Polynomials were fitted to the composition dependence of the MASAs and the correction factors for the different strain states. Fit parameters are given in the paper.

  12. Fabrication of HfO2 patterns by laser interference nanolithography and selective dry etching for III-V CMOS application

    PubMed Central

    2011-01-01

    Nanostructuring of ultrathin HfO2 films deposited on GaAs (001) substrates by high-resolution Lloyd's mirror laser interference nanolithography is described. Pattern transfer to the HfO2 film was carried out by reactive ion beam etching using CF4 and O2 plasmas. A combination of atomic force microscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy microanalysis was used to characterise the various etching steps of the process and the resulting HfO2/GaAs pattern morphology, structure, and chemical composition. We show that the patterning process can be applied to fabricate uniform arrays of HfO2 mesa stripes with tapered sidewalls and linewidths of 100 nm. The exposed GaAs trenches were found to be residue-free and atomically smooth with a root-mean-square line roughness of 0.18 nm after plasma etching. PACS: Dielectric oxides 77.84.Bw, Nanoscale pattern formation 81.16.Rf, Plasma etching 52.77.Bn, Fabrication of III-V semiconductors 81.05.Ea PMID:21711946

  13. Polarity-Driven Quasi-3-Fold Composition Symmetry of Self-Catalyzed III-V-V Ternary Core-Shell Nanowires.

    PubMed

    Zhang, Yunyan; Sanchez, Ana M; Wu, Jiang; Aagesen, Martin; Holm, Jeppe V; Beanland, Richard; Ward, Thomas; Liu, Huiyun

    2015-05-13

    A quasi-3-fold composition symmetry has for the first time been observed in self-catalyzed III-V-V core-shell nanowires. In GaAsP nanowires, phosphorus-rich sheets on radial {110} planes originating at the corners of the hexagonal core were observed. In a cross section, they appear as six radial P-rich bands that originate at the six outer corners of the hexagonal core, with three of them higher in P content along ⟨112⟩A direction and others along ⟨112⟩B, forming a quasi-3-fold composition symmetry. We propose that these P-rich bands are caused by a curvature-induced high surface chemical potential at the small corner facets, which drives As adatoms away more efficiently than P adatoms. Moreover, their polarity related P content difference can be explained by the different adatom bonding energies at these polar corner facets. These results provide important information on the further development of shell growth in the self-catalyzed core-shell NW structure and, hence, device structure for multicomponent material systems.

  14. The role of the substrate on the dispersion in accumulation in III-V compound semiconductor based metal-oxide-semiconductor gate stacks

    SciTech Connect

    Krylov, Igor; Ritter, Dan; Eizenberg, Moshe

    2015-09-07

    Dispersion in accumulation is a widely observed phenomenon in metal-oxide-semiconductor gate stacks based on III-V compound semiconductors. The physical origin of this phenomenon is attributed to border traps located in the dielectric material adjacent to the semiconductor. Here, we study the role of the semiconductor substrate on the electrical quality of the first layers at atomic layer deposited (ALD) dielectrics. For this purpose, either Al{sub 2}O{sub 3} or HfO{sub 2} dielectrics with variable thicknesses were deposited simultaneously on two technology important semiconductors—InGaAs and InP. Significantly larger dispersion was observed in InP based gate stacks compared to those based on InGaAs. The observed difference is attributed to a higher border trap density in dielectrics deposited on InP compared to those deposited on InGaAs. We therefore conclude that the substrate plays an important role in the determination of the electrical quality of the first dielectric monolayers deposited by ALD. An additional observation is that larger dispersion was obtained in HfO{sub 2} based capacitors compared to Al{sub 2}O{sub 3} based capacitors, deposited on the same semiconductor. This phenomenon is attributed to the lower conduction band offset rather than to a higher border trap density.

  15. Revetements antireflet-passivation a base de nitrure de silicium PECVD pour cellules solaires triple-jonction III-V/ Ge

    NASA Astrophysics Data System (ADS)

    Homier, Ram

    Dans le contexte environnemental actuel, le photovoltaïque bénéficie de l'augmentation des efforts de recherche dans le domaine des énergies renouvelables. Pour réduire le coût de la production d'électricité par conversion directe de l'énergie lumineuse en électricité, le photovoltaïque concentré est intéressant. Le principe est de concentrer une grande quantité d'énergie lumineuse sur des petites surfaces de cellules solaires multi-jonction à haute efficacité. Lors de la fabrication d'une cellule solaire, il est essentiel d'inclure une méthode pour réduire la réflexion de la lumière à la surface du dispositif. Le design d'un revêtement antireflet (ARC) pour cellules solaires multi-jonction présente des défis à cause de la large bande d'absorption et du besoin d'égaliser le courant produit par chaque sous-cellule. Le nitrure de silicium déposé par PECVD en utilisant des conditions standards est largement utilisé dans l'industrie des cellules solaires à base de silicium. Cependant, ce diélectrique présente de l'absorption dans la plage des courtes longueurs d'onde. Nous proposons l'utilisation du nitrure de silicium déposé par PECVD basse fréquence (LFSiN) optimisé pour avoir un haut indice de réfraction et une faible absorption optique pour l'ARC pour cellules solaires triple-jonction III-V/Ge. Ce matériau peut aussi servir de couche de passivation/encapsulation. Les simulations montrent que l'ARC double couche SiO2/LFSiN peut être très efficace pour réduire les pertes par réflexion dans la plage de longueurs d'onde de la sous-cellule limitante autant pour des cellules solaires triple-jonction limitées par la sous-cellule du haut que pour celles limitées par la sous-cellule du milieu. Nous démontrons aussi que la performance de la structure est robuste par rapport aux fluctuations des paramètres des couches PECVD (épaisseurs, indice de réfraction). Mots-clés : Photovoltaïque concentré (CPV), cellules

  16. Alloy materials

    DOEpatents

    Hans Thieme, Cornelis Leo; Thompson, Elliott D.; Fritzemeier, Leslie G.; Cameron, Robert D.; Siegal, Edward J.

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

  17. 30 CFR 57.22202 - Main fans (I-A, I-B, I-C, II-A, III, V-A, and V-B mines).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards for Methane in Metal and Nonmetal Mines Ventilation § 57.22202... alloy fan blades shall not contain more than 0.5 percent magnesium. . (d) When an internal...

  18. 10 Gbit/s all-optical NRZ-OOK to RZ-OOK format conversion in an ultra-small III-V-on-silicon microdisk fabricated in a CMOS pilot line.

    PubMed

    Kumar, Rajesh; Spuesens, Thijs; Mechet, Pauline; Olivier, Nicolas; Fedeli, Jean-Marc; Regreny, Philippe; Roelkens, Gunther; van Thourhout, Dries; Morthier, Geert

    2011-11-21

    We report the demonstration of an all-optical, bias free and error-free (bit-error-rate ~10(-12)), 10 Gbit/s non-return-to-zero (NRZ) to return-to-zero (RZ) data format conversion using a 7.5 µm diameter III-V-on-silicon microdisk resonator. The device is completely processed in a 200 mm CMOS pilot line. The data format conversion is based on the phenomenon of pulse carving of an NRZ optical data stream by an optical clock. The underlying physical effect for the pulse carving is the change in the refractive index caused by the generation of free-carriers in a pump -probe configuration. We believe it to be the first NRZ-to-RZ format convertor built on a hybrid III-V-on-silicon technology platform.

  19. Investigating the growth, structural and electrical properties of III-V semiconductor nanopillars for the next-generation electronic and optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Lin, Andrew

    Extensive research efforts have been devoted to the study and development of III-V compound semiconductor nanowires (NWs) and nanopillars (NPs) because of their unique physical properties and ability to form high quality, highly lattice-mismatched axial and radial heterostructures. These advantages lead to precise nano-bandgap engineering to achieve new device functionalities. One unique and powerful approach to realize these NPs is by catalyst-free, selective-area epitaxy (SAE) via metal-organic chemical vapor deposition, in which the NP location and diameter can be precisely controlled lithographically. Early demonstrations of electronic and optoelectronic devices based on these NPs, however, are often inferior compared to their planar counterparts due to a few factors: (1) interface/surface states, (2) inaccurate doping calibration, and (3) increased carrier scattering and trapping from stacking fault formation in the NPs. In this study, the detailed growth mechanisms of different III-As, III-Sb and III-P NPs and their heterostructures are investigated. These NPs are then fabricated into single-NP field-effect transistors (FETs) to probe their electrical properties. It is shown that these devices are highly diameter-dependent, mainly because of the effects of surface states. By growing a high band-gap shell around the NP cores to passivate the surface, the device performance can be significantly improved. Further fabrication and characterization of vertical surround-gate FETs using a high-mobility InAs/InP NP channel is also discussed. Aside from the radial NP heterostructures, different approaches to achieve purely axial heterostructures in InAs/In(As)P materials are also presented with excellent interface quality. Both single barrier and double barrier structures are realized and fabricated into devices that show carrier transport characteristics over a barrier and even resonant tunneling behavior. Antimonide-based NPs are also studied for their immense

  20. Absorption enhancement of GaInP nanowires by tailoring transparent shell thicknesses and its application in III-V nanowire/Si film two-junction solar cells.

    PubMed

    Li, Xinhua; Shi, Tongfei; Liu, Guangqiang; Wen, Long; Zhou, BuKang; Wang, Yuqi

    2015-09-21

    A non-absorbing transparent shell is proposed to be coated on the outer surface of the core photoactive GaInP nanowire array (NWA) of the III-V nanowire (NW)/Si film two-junction solar cell. Interestingly, the diluted (at the filling ratio of 0.25) GaInP NWA with core / transparent shell structure can absorb more light than that in bare denser (at the filling ratio of 0.5) NWA. This allows for less source material consumption during the fabrication of III-V NWA/Si film two-junction cell. Meanwhile, the condition of current matching between the top III-V NWA and Si film sub cell can be easily fulfilled by tailoring the coating thickness of the transparent coating. Beyond the advantages on light absorption, the surface passivation effects introduced by the addition of some transparent dielectric coatings can reduce the surface recombination rate at the top NWA sub cell surface. This facilitates the effective extraction of photo-generated carriers and enhances output stability of the top NWA sub cell. From electrical simulation, a power conversion efficiency of 29.9% can be obtained at the optimized coating geometry.

  1. Simulated characteristics of a heterojunction phototransistor with Ge1-xSnx alloy as base

    NASA Astrophysics Data System (ADS)

    Kumar, Dur Vesh; Pandey, Ankit Kumar; Basu, Rikmantra; Sharma, Anuj K.

    2016-12-01

    Groups III-V compound semiconductors and their alloys are the main photodetecting elements for the entire fiber optic telecommunication band. However, the recent successful growth of GeSnx alloy on Ge virtual substrates on Si platform makes the group IV alloys a potential competitor. GeSnx alloy shows direct band gap and has an absorption coefficient almost 10 times higher than that of Ge. The photonic devices are complementary metal-oxide-semiconductor compatible. We have considered an n-Ge/p+-GeSnx/n-GeSnx heterojunction phototransistor (HPT) and studied the variations of terminal currents by considering the Gummel Poon model of HPT, and values of optical and current gains, photocurrent, and responsivity have been obtained. The performance of the device as a photodetector at fiber optic communication wavelengths seems quite encouraging to justify the use of GeSn-based HPTs as a replacement of III-IV semiconductor-based photodetectors.

  2. III-V semiconductor Quantum Well systems: Physics of Gallium Arsenide two-dimensional hole systems and engineering of mid-infrared Quantum Cascade lasers

    NASA Astrophysics Data System (ADS)

    Chiu, YenTing

    This dissertation examines two types of III-V semiconductor quantum well systems: two-dimensional holes in GaAs, and mid-infrared Quantum Cascade lasers. GaAs holes have a much reduced hyperfine interaction with the nuclei due to the p-like orbital, resulting in a longer hole spin coherence time comparing to the electron spin coherence time. Therefore, holes' spins are promising candidates for quantum computing qubits, but the effective mass and the Lande g-factor, whose product determines the spin-susceptibility of holes, are not well known. In this thesis, we measure the effective hole mass through analyzing the temperature dependence of Shubnikov-de Haas oscillations in a relatively strong interacting two-dimensional hole systems confined to a 20 nm-wide, (311)A GaAs quantum well. The holes in this system occupy two nearly-degenerate spin subbands whose effective mass we measure to be ˜ 0.2 me. We then apply a sufficiently strong parallel magnetic field to fully depopulate one of the spin subbands, and the spin susceptibility of the two-dimensional hole system is deduced from the depopulation field. We also confine holes in closely spaced bilayer GaAs quantum wells to study the interlayer tunneling spectrum as a function of interlayer bias and in-plane magnetic field, in hope of probing the hole's Fermi contour. Quantum Cascade lasers are one of the major mid-infrared light sources well suited for applications in health and environmental sensing. One of the important factors that affect Quantum Cascade laser performance is the quality of the interfaces between the epitaxial layers. What has long been neglected is that interface roughness causes intersubband scattering, and thus affecting the relation between the lifetimes of the upper and lower laser states, which determines if population inversion is possible. We first utilize strategically added interface roughness in the laser design to engineer the intersubband scattering lifetimes. We further

  3. Casting alloys.

    PubMed

    Wataha, John C; Messer, Regina L

    2004-04-01

    Although the role of dental casting alloys has changed in recent years with the development of improved all-ceramic materials and resin-based composites, alloys will likely continue to be critical assets in the treatment of missing and severely damaged teeth. Alloy shave physical, chemical, and biologic properties that exceed other classes of materials. The selection of the appropriate dental casting alloy is paramount to the long-term success of dental prostheses,and the selection process has become complex with the development of many new alloys. However, this selection process is manageable if the practitioner focuses on the appropriate physical and biologic properties, such as tensile strength, modulus of elasticity,corrosion, and biocompatibility, and avoids dwelling on the less important properties of alloy color and short-term cost. The appropriate selection of an alloy helps to ensure a longer-lasting restoration and better oral health for the patient.

  4. VANADIUM ALLOYS

    DOEpatents

    Smith, K.F.; Van Thyne, R.J.

    1959-05-12

    This patent deals with vanadium based ternary alloys useful as fuel element jackets. According to the invention the ternary vanadium alloys, prepared in an arc furnace, contain from 2.5 to 15% by weight titanium and from 0.5 to 10% by weight niobium. Characteristics of these alloys are good thermal conductivity, low neutron capture cross section, good corrosion resistance, good welding and fabricating properties, low expansion coefficient, and high strength.

  5. BRAZING ALLOYS

    DOEpatents

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1963-02-26

    A brazing alloy which, in the molten state, is characterized by excellent wettability and flowability, said alloy being capable of forming a corrosion resistant brazed joint wherein at least one component of said joint is graphite and the other component is a corrosion resistant refractory metal, said alloy consisting essentially of 20 to 50 per cent by weight of gold, 20 to 50 per cent by weight of nickel, and 15 to 45 per cent by weight of molybdenum. (AEC)

  6. Simulation study of 14-nm-gate III-V trigate field effect transistor devices with In1-xGaxAs channel capping layer

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Hao; Li, Yiming

    2015-06-01

    In this work, we study characteristics of 14-nm-gate InGaAs-based trigate MOSFET (metal-oxide-semiconductor field effect transistor) devices with a channel capping layer. The impacts of thickness and gallium (Ga) concentration of the channel capping layer on the device characteristic are firstly simulated and optimized by using three-dimensional quantum-mechanically corrected device simulation. Devices with In1-xGaxAs/In0.53Ga0.47As channels have the large driving current owing to small energy band gap and low alloy scattering at the channel surface. By simultaneously considering various physical and switching properties, a 4-nm-thick In0.68Ga0.32As channel capping layer can be adopted for advanced applications. Under the optimized channel parameters, we further examine the effects of channel fin angle and the work-function fluctuation (WKF) resulting from nano-sized metal grains of NiSi gate on the characteristic degradation and variability. To maintain the device characteristics and achieve the minimal variation induced by WKF, the physical findings of this study indicate a critical channel fin angle of 85o is needed for the device with an averaged grain size of NiSi below 4x4 nm2.

  7. PILOT EVALUATION OF VANADIUM ALLOYS.

    DTIC Science & Technology

    ARCS, SHEETS, ROLLING(METALLURGY), HIGH TEMPERATURE, SCIENTIFIC RESEARCH, COMPRESSIVE PROPERTIES, DUCTILITY, CREEP, OXIDATION, COATINGS , SILICIDES , HARDNESS, WELDING, EXTRUSION, TANTALUM ALLOYS, MOLYBDENUM ALLOYS....VANADIUM ALLOYS, * NIOBIUM ALLOYS, MECHANICAL PROPERTIES, MECHANICAL PROPERTIES, TITANIUM ALLOYS, ZIRCONIUM ALLOYS, CARBON ALLOYS, MELTING, ELECTRIC

  8. Nonswelling alloy

    DOEpatents

    Harkness, S.D.

    1975-12-23

    An aluminum alloy containing one weight percent copper has been found to be resistant to void formation and thus is useful in all nuclear applications which currently use aluminum or other aluminum alloys in reactor positions which are subjected to high neutron doses.

  9. URANIUM ALLOYS

    DOEpatents

    Seybolt, A.U.

    1958-04-15

    Uranium alloys containing from 0.1 to 10% by weight, but preferably at least 5%, of either zirconium, niobium, or molybdenum exhibit highly desirable nuclear and structural properties which may be improved by heating the alloy to about 900 d C for an extended period of time and then rapidly quenching it.

  10. ZIRCONIUM ALLOY

    DOEpatents

    Wilhelm, H.A.; Ames, D.P.

    1959-02-01

    A binary zirconiuin--antimony alloy is presented which is corrosion resistant and hard containing from 0.07% to 1.6% by weight of Sb. The alloys have good corrosion resistance and are useful in building equipment for the chemical industry.

  11. Compound semiconductor alloys: From atomic-scale structure to bandgap bowing

    NASA Astrophysics Data System (ADS)

    Schnohr, C. S.

    2015-09-01

    Compound semiconductor alloys such as InxGa1-xAs, GaAsxP1-x, or CuInxGa1-xSe2 are increasingly employed in numerous electronic, optoelectronic, and photonic devices due to the possibility of tuning their properties over a wide parameter range simply by adjusting the alloy composition. Interestingly, the material properties are also determined by the atomic-scale structure of the alloys on the subnanometer scale. These local atomic arrangements exhibit a striking deviation from the average crystallographic structure featuring different element-specific bond lengths, pronounced bond angle relaxation and severe atomic displacements. The latter, in particular, have a strong influence on the bandgap energy and give rise to a significant contribution to the experimentally observed bandgap bowing. This article therefore reviews experimental and theoretical studies of the atomic-scale structure of III-V and II-VI zincblende alloys and I-III-VI2 chalcopyrite alloys and explains the characteristic findings in terms of bond length and bond angle relaxation. Different approaches to describe and predict the bandgap bowing are presented and the correlation with local structural parameters is discussed in detail. The article further highlights both similarities and differences between the cubic zincblende alloys and the more complex chalcopyrite alloys and demonstrates that similar effects can also be expected for other tetrahedrally coordinated semiconductors of the adamantine structural family.

  12. Structural properties of bismuth-bearing semiconductor alloys

    NASA Technical Reports Server (NTRS)

    Berding, M. A.; Sher, A.; Chen, A. B.

    1986-01-01

    The structural properties of bismuth-bearing III-V semiconductor alloys are addressed. Because the Bi compounds are not known to form zincblende structures, only the anion-substituted alloys InPBi, InAsBi, and InSbBi are considered candidates as narrow-gap semiconductors. Miscibility calculations indicate that InSbBi will be the most miscible, and InPBi, with the large lattice mismatch of the constituents, will be the most difficult to mix. Calculations of the hardness of the Bi compounds indicate that, once formed, the InPBi alloy will be harder than the other Bi alloys, and substantially harder than the currently favored narrow-gap semiconductor HgCdTe. Thus, although InSbBi may be an easier material to prepare, InPBi promises to be a harder material. Growth of the Bi compounds will require high effective growth temperatures, probably attainable only through the use of nonequilibrium energy-assisted epitaxial growth techniques.

  13. PLUTONIUM ALLOYS

    DOEpatents

    Chynoweth, W.

    1959-06-16

    The preparation of low-melting-point plutonium alloys is described. In a MgO crucible Pu is placed on top of the lighter alloying metal (Fe, Co, or Ni) and the temperature raised to 1000 or 1200 deg C. Upon cooling, the alloy slug is broke out of the crucible. With 14 at. % Ni the m.p. is 465 deg C; with 9.5 at. % Fe the m.p. is 410 deg C; and with 12.0 at. % Co the m.p. is 405 deg C. (T.R.H.) l6262 l6263 ((((((((Abstract unscannable))))))))

  14. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  15. BRAZING ALLOYS

    DOEpatents

    Donnelly, R.G.; Gilliland, R.G.; Slaughter, G.M.

    1962-02-20

    A brazing alloy is described which, in the molten state, is characterized by excellent wettability and flowability and is capable of forming a corrosion-resistant brazed joint. At least one component of said joint is graphite and the other component is a corrosion-resistant refractory metal. The brazing alloy consists essentially of 40 to 90 wt % of gold, 5 to 35 wt% of nickel, and 1 to 45 wt% of tantalum. (AEC)

  16. COATED ALLOYS

    DOEpatents

    Harman, C.G.; O'Bannon, L.S.

    1958-07-15

    A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

  17. Multiple doping of silicon-germanium alloys for thermoelectric applications

    NASA Technical Reports Server (NTRS)

    Fleurial, Jean-Pierre; Vining, Cronin B.; Borshchevsky, Alex

    1989-01-01

    It is shown that heavy doping of n-type Si/Ge alloys with phosphorus and arsenic (V-V doping interaction) by diffusion leads to a significant enhancement of their carrier concentration and possible improvement of the thermoelectric figure of merit. High carrier concentrations were achieved by arsenic doping alone, but for a same doping level higher carrier mobilities and lower resistivities are obtained through phosphorus doping. By combining the two dopants with the proper diffusion treatments, it was possible to optimize the different properties, obtaining high carrier concentration, good carrier mobility and low electrical resistivity. Similar experiments, using the III-V doping interaction, were conducted on boron-doped p-type samples and showed the possibility of overcompensating the samples by diffusing arsenic, in order to get n-type behavior.

  18. Kinetic effects and mechanisms limiting substitutional solubility in the formation of supersaturated alloys by pulsed laser annealing

    SciTech Connect

    White, C.W.; Appleton, B.R.; Stritzker, B.; Zehner, D.M.; Wilson, S.R.

    1980-11-01

    Pulsed laser annealing of silicon implanted by Group (III,V) dopants leads to the formation of supersaturated alloys by nonequilibrium processes occurring in the interfacial region during liquid phase epitaxial regrowth. The distribution coefficient from the melt (k') and the maximum dopant substitutional solubility (C/sub s//sup max/) are far greater than equilibrium values and both are functions of growth velocity. Substitutional solubility is limited by lattice strain and by constitutional supercooling at the interface during regrowth. Values for C/sub s//sup max/ obtained at different velocities are compared with predictions of thermodynamic limits for solute trapping.

  19. Systematic approach for simultaneously correcting the band-gap andp-dseparation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

    DOE PAGES

    Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

    2015-07-31

    We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X = N,P,As,Sb, and II-VI compounds, (Zn or Cd)X, with X = O,S,Se,Te. By correcting (1) the binary band gaps at high-symmetry points , L, X, (2) the separation of p-and d-orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles methodmore » can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.« less

  20. Hybrid III-V Silicon Lasers

    NASA Astrophysics Data System (ADS)

    Bowers, John

    2014-03-01

    Abstract: A number of important breakthroughs in the past decade have focused attention on Si as a photonic platform. We review here recent progress in this field, focusing on efforts to make lasers, amplifiers, modulators and photodetectors on or in silicon. We also describe optimum quantum well design and distributed feedback cavity design to reduce the threshold and increase the efficiency and power output. The impact active silicon photonic integrated circuits could have on interconnects, telecommunications and on silicon electronics is reviewed. Biography: John Bowers holds the Fred Kavli Chair in Nanotechnology, and is the Director of the Institute for Energy Efficiency and a Professor in the Departments of Electrical and Computer Engineering and Materials at UCSB. He is a cofounder of Aurrion, Aerius Photonics and Calient Networks. Dr. Bowers received his M.S. and Ph.D. degrees from Stanford University and worked for AT&T Bell Laboratories and Honeywell before joining UC Santa Barbara. Dr. Bowers is a member of the National Academy of Engineering and a fellow of the IEEE, OSA and the American Physical Society. He is a recipient of the OSA/IEEE Tyndall Award, the OSA Holonyak Prize, the IEEE LEOS William Streifer Award and the South Coast Business and Technology Entrepreneur of the Year Award. He and coworkers received the EE Times Annual Creativity in Electronics (ACE) Award for Most Promising Technology for the hybrid silicon laser in 2007. Bowers' research is primarily in optoelectronics and photonic integrated circuits. He has published ten book chapters, 600 journal papers, 900 conference papers and has received 54 patents. He has published 180 invited papers and conference papers, and given 16 plenary talks at conferences. As well as Chong Zhang.

  1. Characterization of III-V Semiconductors.

    DTIC Science & Technology

    1981-04-01

    Epitaxial GaAs by Transient Capacitance ....................... 71 9.5 Persistent Photoconductivity in GaAs: Relationship to Low-Temperature Solar Cell I - V Characteristiss...the DLTS techniqu&. 66 71 __ 9.5 Persistant Photoconductivitv in GaAs:Relationship to Low- Temperature Solar Cell I - V Characteristics The following

  2. Alloy softening in binary molybdenum alloys

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of Hf, Ta, W, Re, Os, Ir, and Pt on the hardness of Mo. Special emphasis was placed on alloy softening in these binary Mo alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to Mo, while those elements having an equal number or fewer s+d electrons than Mo failed to produce alloy softening. Alloy softening and hardening can be correlated with the difference in number of s+d electrons of the solute element and Mo.

  3. GaSb based ternary and quaternary diffused junction devices for TPV applications

    SciTech Connect

    Sundaram, V.S.; Saban, S.B.; Morgan, M.D.; Horne, W.E.; Evans, B.D.; Ketterl, J.R.; Morosini, M.B.; Patel, N.B.; Field, H.

    1997-03-01

    In this work we report the characteristics of ternary, GaInSb (Eg=0.70eV) and quarternary, GaInAsSb (Eg=0.5eV) diffused junction photovoltaic devices. The unique feature of the quarternary device is the extended long-wavelength response to 2.1 microns enabling the efficient use of the blackbody-like thermal sources operating at 1373 K in thermophotovoltaic energy conversion systems. The ternary device was fabricated by diffusing zinc into a n-type (100) oriented GaInSb substrate. For the quarternary, a four micron thick Te doped GaInAsSb layer grown by LPE on a n-type GaSb(100) wafer was used as the starting substrate for zinc diffusion. The ternary device exhibits an open circuit voltage of 0.38 V, Fill Factor of 0.63 and a short circuit current of 0.8A/cm{sup 2}, while the corresponding values for the quarternary device are 0.25 V, 0.58 and 0.8A/cm{sup 2}, respectively. The peak internal quantum efficiency for the ternary is over 90{percent} and that of the quarternary is above 75{percent}. Process optimization should improve the performance charcateristics of the quarternary. {copyright} {ital 1997 American Institute of Physics.}

  4. Distributed feedback GaSb based laser diodes with buried grating

    SciTech Connect

    Gaimard, Q.; Cerutti, L.; Teissier, R.; Vicet, A.

    2014-04-21

    We report on the growth, fabrication, and experimental study of distributed feed-back antimonide diode lasers with buried grating. A second order index-coupled grating was defined by interferometric lithography on the top of the laser waveguide and dry etched by reactive ion etching. The grating was then buried thanks to an overgrowth of the top cladding layer using molecular beam epitaxy. The wafer was then processed using standard photolithography and wet etching into 15 μm-wide laser ridges. Single frequency laser emission at a wavelength of 2.2 μm was measured with a side mode suppression ratio of 34 dB, a maximum output power of 30 mW, and a total continuous tuning range of 6.5 nm.

  5. The C-terminal N-glycosylation sites of the human alpha1,3/4-fucosyltransferase III, -V, and -VI (hFucTIII, -V, adn -VI) are necessary for the expression of full enzyme activity.

    PubMed

    Christensen, L L; Jensen, U B; Bross, P; Orntoft, T F

    2000-09-01

    The alpha1,3/4-fucosyltransferases are involved in the synthesis of fucosylated cell surface glycoconjugates. Human alpha1,3/4-fucosyltransferase III, -V, and -VI (hFucTIII, -V, and -VI) contain two conserved C-terminal N-glycosylation sites (hFucTIII: Asn154 and Asn185; hFucTV: Asn167 and Asn198; and hFucTVI: Asn153 and Asn184). In the present study, we have analyzed the functional role of these potential N-glycosylation sites, laying the main emphasis on the sites in hFucTIII. Tunicamycin treatment completely abolished hFucTIII enzyme activity while castanospermine treatment diminished hFucTIII enzyme activity to approximately 40% of the activity of the native enzyme. To further analyze the role of the conserved N-glycosylation sites in hFucTIII, -V, and -VI, we made a series of mutant genomic DNAs in which the asparagine residues in the potential C-terminal N-glycosylation sites were replaced by glutamine. Subsequently, the hFucTIII, -V, and -VI wild type and the mutants were expressed in COS-7 cells. All the mutants exhibited lower enzyme activity than the wild type and elimination of individual sites had different effects on the activity. The mutations did not affect the protein level of the mutants in the cells, but reduced the molecular mass as predicted. Kinetic analysis of hFucTIII revealed that lack of glycosylation at Asn185 did not change the Km values for the oligosaccharide acceptor and the nucleotide sugar donor. The present study demonstrates that hFucTIII, -V, and -VI require N-glycosylation at the two conserved C-terminal N-glycosylation sites for expression of full enzyme activity.

  6. Metal alloy identifier

    DOEpatents

    Riley, William D.; Brown, Jr., Robert D.

    1987-01-01

    To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

  7. First-principles calculation on dilute magnetic alloys in zinc blend crystal structure

    NASA Astrophysics Data System (ADS)

    Ullah, Hamid; Inayat, Kalsoom; Khan, S. A.; Mohammad, S.; Ali, A.; Alahmed, Z. A.; Reshak, A. H.

    2015-07-01

    Ab-initio calculations are performed to investigate the structural, electronic and magnetic properties of spin-polarized diluted magnetic alloys in zinc blende structure. The first-principles study is carried out on Mn doped III-V semiconductors. The calculated band structures, electronic properties and magnetic properties of Ga1-xMnxX (X=P, As) compounds reveal that Ga0.75Mn0.25P is half metallic turned to be metallic with increasing x to 0.5 and 0.75, whereas substitute P by As cause to maintain the half-metallicity nature in both of Ga0.75Mn0.25As and Ga0.5Mn0.5As and tune Ga0.25Mn0.75As to be metallic. Calculated total magnetic moments and the robustness of half-metallicity of Ga0.75Mn0.25P, Ga0.75Mn0.25As and Ga0.5Mn0.5As with respect to the variation in lattice parameters are also discussed. The predicted theoretical evidence shows that some Mn-doped III-V semiconductors can be effectively used in spintronic devices.

  8. Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

    DOEpatents

    Spahn, Olga B.; Lear, Kevin L.

    1998-01-01

    A semiconductor structure. The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g. Al.sub.2 O.sub.3), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3-1.6 .mu.m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation.

  9. Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

    DOEpatents

    Spahn, O.B.; Lear, K.L.

    1998-03-10

    The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g., Al{sub 2}O{sub 3}), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3--1.6 {mu}m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation. 10 figs.

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

    SciTech Connect

    Calabrese, Gabriele; Baricordi, Stefano; Bernardoni, Paolo; Fin, Samuele; Guidi, Vincenzo; Vincenzi, Donato

    2014-09-26

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

  11. Films of Soft-Magnetic Fe-Based Nanocrystalline Alloys for High-Density Magnetic Storage Application

    NASA Astrophysics Data System (ADS)

    Shefteľ, E. N.; Bannykh, O. A.

    This paper presents a review of works related to the problem of development of soft-magnetic film Fe-based alloys exhibiting the combination of properties, such as the high saturation inductance, high level of soft-magnetic parameters over a wide range of MHz-frequencies, high wear-resistance and thermal stability, and an ability to be prepared by thin-film technologies. Magnetic cores of high-density recording heads are the principal application of these materials. Physical fundamentals of explanation of ferromagnetic behavior of a material with nano-sized structure, which have been developed for FINEMETs (Fe-Nb-Cu-Si-B) with the mixed amorphous + nanocrystalline structure, are considered. A new class of alloys Fe-Me-X (Me=Metal of III-V groups of the Periodic Table and X=C, N, O, and B) whose properties are higher that those of FINEMETs are discussed. The structure of these alloys consists of two nanocrystalline phases, such as the ferromagnetic α-Fe-based and nonmagnetic MeX phases. This structure provides the dispersion strengthening of the alloys. Metal science approaches to the selection of both chemical compositions and conditions of structure formation for these film alloys have been developed by authors and are discussed in this article.

  12. SUPERCONDUCTING VANADIUM BASE ALLOY

    DOEpatents

    Cleary, H.J.

    1958-10-21

    A new vanadium-base alloy which possesses remarkable superconducting properties is presented. The alloy consists of approximately one atomic percent of palladium, the balance being vanadium. The alloy is stated to be useful in a cryotron in digital computer circuits.

  13. Weldability of intermetallic alloys

    SciTech Connect

    David, S.A. )

    1990-01-01

    Ordered intermetallic alloys are a unique class of material that have potential for structural applications at elevated temperatures. The paper describes the welding and weldability of these alloys. The alloys studied were nickel aluminide (Ni[sub 3]Al), titanium aluminide (Ti[sub 3]Al), and iron aluminide.

  14. DELTA PHASE PLUTONIUM ALLOYS

    DOEpatents

    Cramer, E.M.; Ellinger, F.H.; Land. C.C.

    1960-03-22

    Delta-phase plutonium alloys were developed suitable for use as reactor fuels. The alloys consist of from 1 to 4 at.% zinc and the balance plutonium. The alloys have good neutronic, corrosion, and fabrication characteristics snd possess good dimensional characteristics throughout an operating temperature range from 300 to 490 deg C.

  15. PLUTONIUM-THORIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.

    1959-09-15

    New plutonium-base binary alloys useful as liquid reactor fuel are described. The alloys consist of 50 to 98 at.% thorium with the remainder plutonium. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are easy fabrication, phase stability, and the accompanying advantuge of providing a means for converting Th/sup 232/ into U/sup 233/.

  16. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  17. Rhenium alloying of tungsten heavy alloys

    SciTech Connect

    German, R.M.; Bose, A.; Jerman, G.

    1989-01-01

    Alloying experiments were performed using rhenium additions to a classic 90 mass % tungsten heavy alloy. The mixed-powder system was liquid phase sintered to full density at 1500 C in 60 min The rhenium-modified alloys exhibited a smaller grain size, higher hardness, higher strength, and lower ductility than the unalloyed system. For an alloy with a composition of 84W-6Re-8Ni-2Fe, the sintered density was 17, 4 Mg/m{sup 3} with a yield strength of 815 MPa, tensile strength of 1180 MPa, and elongation to failure of 13%. This property combination results from the aggregate effects of grain size reduction and solid solution hardening due to rhenium. In the unalloyed system these properties require post-sintering swaging and aging; thus, alloying with rhenium is most attractive for applications where net shaping is desired, such as by powder injection molding.

  18. Processing and alloying of tungsten heavy alloys

    SciTech Connect

    Bose, A.; Dowding, R.J.

    1993-12-31

    Tungsten heavy alloys are two-phase metal matrix composites with a unique combination of density, strength, and ductility. They are processed by liquid-phase sintering of mixed elemental powders. The final microstructure consists of a contiguous network of nearly pure tungsten grains embedded in a matrix of a ductile W-Ni-Fe alloy. Due to the unique property combination of the material, they are used extensively as kinetic energy penetrators, radiation shields. counterbalances, and a number of other applications in the defense industry. The properties of these alloys are extremely sensitive to the processing conditions. Porosity levels as low as 1% can drastically degrade the properties of these alloys. During processing, care must be taken to reduce or prevent incomplete densification, hydrogen embrittlement, impurity segregation to the grain boundaries, solidification shrinkage induced porosity, and in situ formation of pores due to the sintering atmosphere. This paper will discuss some of the key processing issues for obtaining tungsten heavy alloys with good properties. High strength tungsten heavy alloys are usually fabricated by swaging and aging the conventional as-sintered material. The influence of this on the shear localization tendency of a W-Ni-Co alloy will also be demonstrated. Recent developments have shown that the addition of certain refractory metals partially replacing tungsten can significantly improve the strength of the conventional heavy alloys. This development becomes significant due to the recent interest in near net shaping techniques such as powder injection moldings. The role of suitable alloying additions to the classic W-Ni-Fe based heavy alloys and their processing techniques will also be discussed in this paper.

  19. Extrusion of aluminium alloys

    SciTech Connect

    Sheppard, T.

    1999-01-01

    In recent years the importance of extruded alloys has increased due to the decline in copper extrusion, increased use in structural applications, environmental impact and reduced energy consumption. There have also been huge technical advances. This text provides comprehensive coverage of the metallurgical, mathematical and practical features of the process. The contents include: continuum principles; metallurgical features affecting the extrusion of Al-alloys; extrusion processing; homogenization and extrusion conditions for specific alloys; processing of 6XXX alloys; plant utilization; Appendix A: specification of AA alloys and DIN equivalents; Appendix B: chemical compositions; and Appendix C: typical properties.

  20. High strength alloys

    DOEpatents

    Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

    2010-08-31

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

  1. High strength alloys

    DOEpatents

    Maziasz, Phillip James; Shingledecker, John Paul; Santella, Michael Leonard; Schneibel, Joachim Hugo; Sikka, Vinod Kumar; Vinegar, Harold J.; John, Randy Carl; Kim, Dong Sub

    2012-06-05

    High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tublar that is at least partially made from a material containing at least one of the metal alloys.

  2. Interacting quasi-band theory for electronic states in compound semiconductor alloys: Wurtzite structure

    NASA Astrophysics Data System (ADS)

    Kishi, Ayaka; Oda, Masato; Shinozuka, Yuzo

    2016-05-01

    This paper reports on the electronic states of compound semiconductor alloys of wurtzite structure calculated by the recently proposed interacting quasi-band (IQB) theory combined with empirical sp3 tight-binding models. Solving derived quasi-Hamiltonian 24 × 24 matrix that is characterized by the crystal parameters of the constituents facilitates the calculation of the conduction and valence bands of wurtzite alloys for arbitrary concentrations under a unified scheme. The theory is applied to III-V and II-VI wurtzite alloys: cation-substituted Al1- x Ga x N and Ga1- x In x N and anion-substituted CdS1- x Se x and ZnO1- x S x . The obtained results agree well with the experimental data, and are discussed in terms of mutual mixing between the quasi-localized states (QLS) and quasi-average bands (QAB): the latter bands are approximately given by the virtual crystal approximation (VCA). The changes in the valence and conduction bands, and the origin of the band gap bowing are discussed on the basis of mixing character.

  3. Creep Resistant Zinc Alloy

    SciTech Connect

    Frank E. Goodwin

    2002-12-31

    This report covers the development of Hot Chamber Die Castable Zinc Alloys with High Creep Strengths. This project commenced in 2000, with the primary objective of developing a hot chamber zinc die-casting alloy, capable of satisfactory service at 140 C. The core objectives of the development program were to: (1) fill in missing alloy data areas and develop a more complete empirical model of the influence of alloy composition on creep strength and other selected properties, and (2) based on the results from this model, examine promising alloy composition areas, for further development and for meeting the property combination targets, with the view to designing an optimized alloy composition. The target properties identified by ILZRO for an improved creep resistant zinc die-casting alloy were identified as follows: (1) temperature capability of 1470 C; (2) creep stress of 31 MPa (4500 psi); (3) exposure time of 1000 hours; and (4) maximum creep elongation under these conditions of 1%. The project was broadly divided into three tasks: (1) Task 1--General and Modeling, covering Experimental design of a first batch of alloys, alloy preparation and characterization. (2) Task 2--Refinement and Optimization, covering Experimental design of a second batch of alloys. (3) Task 3--Creep Testing and Technology transfer, covering the finalization of testing and the transfer of technology to the Zinc industry should have at least one improved alloy result from this work.

  4. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  5. Weldability of High Alloys

    SciTech Connect

    Maroef, I

    2003-01-22

    The purpose of this study was to investigate the effect of silicon and iron on the weldability of HAYNES HR-160{reg_sign} alloy. HR-I60 alloy is a solid solution strengthened Ni-Co-Cr-Si alloy. The alloy is designed to resist corrosion in sulfidizing and other aggressive high temperature environments. Silicon is added ({approx}2.75%) to promote the formation of a protective oxide scale in environments with low oxygen activity. HR-160 alloy has found applications in waste incinerators, calciners, pulp and paper recovery boilers, coal gasification systems, and fluidized bed combustion systems. HR-160 alloy has been successfully used in a wide range of welded applications. However, the alloy can be susceptible to solidification cracking under conditions of severe restraint. A previous study by DuPont, et al. [1] showed that silicon promoted solidification cracking in the commercial alloy. In earlier work conducted at Haynes, and also from published work by DuPont et al., it was recognized that silicon segregates to the terminal liquid, creating low melting point liquid films on solidification grain boundaries. Solidification cracking has been encountered when using the alloy as a weld overlay on steel, and when joining HR-160 plate in a thickness greater than19 millimeters (0.75 inches) with matching filler metal. The effect of silicon on the weldability of HR-160 alloy has been well documented, but the effect of iron is not well understood. Prior experience at Haynes has indicated that iron may be detrimental to the solidification cracking resistance of the alloy. Iron does not segregate to the terminal solidification product in nickel-base alloys, as does silicon [2], but iron may have an indirect or interactive influence on weldability. A set of alloys covering a range of silicon and iron contents was prepared and characterized to better understand the welding metallurgy of HR-160 alloy.

  6. Alloy 10: A 1300F Disk Alloy

    NASA Technical Reports Server (NTRS)

    Gayda, John

    2000-01-01

    Gas turbine engines for future subsonic transports will probably have higher pressure ratios which will require nickel-base superalloy disks with 13000 to 1400 F temperature capability. Several advanced disk alloys are being developed to fill this need. One of these, Allied Signal's Alloy 10, is a promising candidate for gas turbine engines to be used on smaller, regional aircraft. For this application, compressor/turbine disks must withstand temperatures of 1300 F for several hundred hours over the life of the engine. In this paper, three key properties of Alloy 10--tensile, 0.2% creep, and fatigue crack growth--will be assessed at 1300 F.

  7. Surface alloying of Mg alloys after surface nanocrystallization.

    PubMed

    Zhang, Ming-Xing; Shi, Yi-Nong; Sun, Haiqing; Kelly, Patrick M

    2008-05-01

    Surface nanocrystallization using a surface mechanical attrition treatment effectively activates the surface of magnesium alloys due to the increase in grain boundary diffusion channels. As a result, the temperature of subsequent surface alloying treatment of pure Mg and AZ91 alloy can be reduced from 430 degrees C to 380 degrees C. Thus, it is possible to combine the surface alloying process with the solution treatment for this type of alloy. After surface alloying, the hardness of the alloyed layer is 3 to 4 times higher than that of the substrate and this may significantly improve the wear resistance of magnesium alloys.

  8. Catalyst Alloys Processing

    NASA Astrophysics Data System (ADS)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  9. Low activation ferritic alloys

    DOEpatents

    Gelles, David S.; Ghoniem, Nasr M.; Powell, Roger W.

    1986-01-01

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  10. Low activation ferritic alloys

    DOEpatents

    Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

    1985-02-07

    Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

  11. Amorphous metal alloy

    DOEpatents

    Wang, R.; Merz, M.D.

    1980-04-09

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  12. PLUTONIUM-ZIRCONIUM ALLOYS

    DOEpatents

    Schonfeld, F.W.; Waber, J.T.

    1960-08-30

    A series of nuclear reactor fuel alloys consisting of from about 5 to about 50 at.% zirconium (or higher zirconium alloys such as Zircaloy), balance plutonium, and having the structural composition of a plutonium are described. Zirconium is a satisfactory diluent because it alloys readily with plutonium and has desirable nuclear properties. Additional advantages are corrosion resistance, excellent fabrication propenties, an isotropie structure, and initial softness.

  13. NICKEL-BASE ALLOY

    DOEpatents

    Inouye, H.; Manly, W.D.; Roche, T.K.

    1960-01-19

    A nickel-base alloy was developed which is particularly useful for the containment of molten fluoride salts in reactors. The alloy is resistant to both salt corrosion and oxidation and may be used at temperatures as high as 1800 deg F. Basically, the alloy consists of 15 to 22 wt.% molybdenum, a small amount of carbon, and 6 to 8 wt.% chromium, the balance being nickel. Up to 4 wt.% of tungsten, tantalum, vanadium, or niobium may be added to strengthen the alloy.

  14. Supersaturated Aluminum Alloy Powders.

    DTIC Science & Technology

    1981-07-15

    shown in Fig. 18 . It .an be clearly seen that most of the iron is concentrated in the precipitates (Fig. 18 ), X-ray mapping immage for the chromium...At 232°C our alloys are comparable to 2� and 2618 in their tensile properties, and except for alloy #1 which at t i temperature has elongation of...demonstrate better yield strength and UTS than the 2219, 2618 and are comparable to the ALCOA alloy. They show however higher ductility than the ALCOA alloy

  15. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A.; Verhoeven, John D.; Gibson, Edwin D.

    1986-07-15

    A tantalum-copper alloy can be made by preparing a consumable electrode consisting of an elongated copper billet containing at least two spaced apart tantalum rods extending longitudinally the length of the billet. The electrode is placed in a dc arc furnace and melted under conditions which co-melt the copper and tantalum to form the alloy.

  16. Ductile transplutonium metal alloys

    SciTech Connect

    Conner, W.V.

    1983-04-19

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  17. Neutron Absorbing Alloys

    SciTech Connect

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  18. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  19. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  20. PLUTONIUM-CERIUM ALLOY

    DOEpatents

    Coffinberry, A.S.

    1959-01-01

    An alloy is presented for use as a reactor fuel. The binary alloy consists essentially of from about 5 to 90 atomic per cent cerium and the balance being plutonium. A complete phase diagram for the cerium--plutonium system is given.

  1. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  2. Ductile transplutonium metal alloys

    DOEpatents

    Conner, W.V.

    1981-10-09

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as souces of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  3. Cesium iodide alloys

    DOEpatents

    Kim, H.E.; Moorhead, A.J.

    1992-12-15

    A transparent, strong CsI alloy is described having additions of monovalent iodides. Although the preferred iodide is AgI, RbI and CuI additions also contribute to an improved polycrystalline CsI alloy with outstanding multispectral infrared transmittance properties. 6 figs.

  4. Alloys in energy development

    SciTech Connect

    Frost, B.R.T.

    1984-02-01

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems.

  5. Ultrahigh temperature intermetallic alloys

    SciTech Connect

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  6. THORIUM-SILICON-BERYLLIUM ALLOYS

    DOEpatents

    Foote, F.G.

    1959-02-10

    Th, Si, anol Bt alloys where Be and Si are each present in anmounts between 0.1 and 3.5% by weight and the total weight per cent of the minor alloying elements is between 1.5 and 4.5% are discussed. These ternary alloys show increased hardness and greater resistant to aqueous corrosion than is found in pure Th, Th-Si alloys, or Th-Be alloys.

  7. Magnesium silicide intermetallic alloys

    NASA Astrophysics Data System (ADS)

    Li, Gh.; Gill, H. S.; Varin, R. A.

    1993-11-01

    Methods of induction melting an ultra-low-density magnesium silicide (Mg2Si) intermetallic and its alloys and the resulting microstructure and microhardness were studied. The highest quality ingots of Mg2Si alloys were obtained by triple melting in a graphite crucible coated with boron nitride to eliminate reactivity, under overpressure of high-purity argon (1.3 X 105 Pa), at a temperature close to but not exceeding 1105 °C ± 5 °C to avoid excessive evaporation of Mg. After establishing the proper induction-melting conditions, the Mg-Si binary alloys and several Mg2Si alloys macroalloyed with 1 at. pct of Al, Ni, Co, Cu, Ag, Zn, Mn, Cr, and Fe were induction melted and, after solidification, investigated by optical microscopy and quantitative X-ray energy dispersive spectroscopy (EDS). Both the Mg-rich and Si-rich eutectic in the binary alloys exhibited a small but systematic increase in the Si content as the overall composition of the binary alloy moved closer toward the Mg2Si line compound. The Vickers microhardness (VHN) of the as-solidified Mg-rich and Si-rich eutectics in the Mg-Si binary alloys decreased with increasing Mg (decreasing Si) content in the eutectic. This behavior persisted even after annealing for 75 hours at 0.89 pct of the respective eutectic temperature. The Mg-rich eutectic in the Mg2Si + Al, Ni, Co, Cu, Ag, and Zn alloys contained sections exhibiting a different optical contrast and chemical composition than the rest of the eutectic. Some particles dispersed in the Mg2Si matrix were found in the Mg2Si + Cr, Mn, and Fe alloys. The EDS results are presented and discussed and compared with the VHN data.

  8. TUNGSTEN BASE ALLOYS

    DOEpatents

    Schell, D.H.; Sheinberg, H.

    1959-12-15

    A high-density quaternary tungsten-base alloy having high mechanical strength and good machinability composed of about 2 wt.% Ni, 3 wt.% Cu, 5 wt.% Pb, and 90wt.% W is described. This alloy can be formed by the powder metallurgy technique of hot pressing in a graphite die without causing a reaction between charge and the die and without formation of a carbide case on the final compact, thereby enabling re-use of the graphite die. The alloy is formable at hot- pressing temperatures of from about 1200 to about 1350 deg C. In addition, there is little component shrinkage, thereby eliminating the necessity of subsequent extensive surface machining.

  9. Electrical Resistivity of Ten Selected Binary Alloy Systems.

    DTIC Science & Technology

    1981-04-01

    alloys --* Aluminum Alloys --*Copper alloys --*Gold alloys --*Nickel Alloys --*Silver alloys --*Iron alloys --*Palladium alloys ... aluminum -magnesium, and copper-zinc) are given for 27 compositions: 0 (pure element).* For aluminum -copper, aluninu.-eagnes tur, end copper-zinc alloy ...available data and infor- mation. The ten binary alloy systems selected are the systems of aluminum - copper, aluminum -magnesium, copper-gold,

  10. First-principles calculations of bismuth induced changes in the band structure of dilute Ga-V-Bi and In-V-Bi alloys: chemical trends versus experimental data

    NASA Astrophysics Data System (ADS)

    Polak, M. P.; Scharoch, P.; Kudrawiec, R.

    2015-09-01

    Bi-induced changes in the band structure of Ga-V-Bi and In-V-Bi alloys are calculated within the density functional theory (DFT) for alloys with Bi ≤3.7% and the observed chemical trends are discussed in the context of the virtual crystal approximation (VCA) and the valence band anticrossing (VBAC) model. It is clearly shown that the incorporation of Bi atoms into III-V host modifies both the conduction band (CB) and the valence band (VB). The obtained shifts of bands in GaP1-xBix, GaAs1-xBix, GaSb1-xBix, InP1-xBix, InAs1-xBix, and InSb1-xBix are respectively, 15, -29, -16, -27, -15, and -10 meV/%Bi for CB, 82, 62, 16, 79, 45, and 16 meV/%Bi for VB, and -17, -3, -2, -8, -6, and 14 meV/%Bi for spin-orbit split off band. The Bi-induced reduction of the band gap is very consistent with the available experimental data. The chemical trends observed in our calculations as well as in experimental data are very clear: in a sequence of alloys from III-P-Bi to III-Sb-Bi the Bi-induced changes in the band structure weaken. For dilute GaSb1-xBix and InSb1-xBix alloys the band structure modification, in the first approximation, can be described within the VCA, while for Ga-V-Bi and In-V-Bi alloys with V = As or P another phenomenological approach is needed to predict the Bi-induced changes in their band structure. We have found that a combination of the VCA with the VBAC model, which is widely applied for highly mismatched alloys, is suitable for this purpose. The chemical trends for III-V-Bi alloys observed in our DFT calculations are also exhibited by the coupling parameter {C}BiM, which describes the magnitude of interaction between Bi-induced levels and VB states in the VBAC model. This coupling parameter monotonously decreases along the sequence of alloys from III-P-Bi to III-Sb-Bi.

  11. Electroplating on titanium alloy

    NASA Technical Reports Server (NTRS)

    Lowery, J. R.

    1971-01-01

    Activation process forms adherent electrodeposits of copper, nickel, and chromium on titanium alloy. Good adhesion of electroplated deposits is obtained by using acetic-hydrofluoric acid anodic activation process.

  12. Alloy Selection System

    SciTech Connect

    2001-02-01

    Software will Predict Corrosion Rates to Improve Productivity in the Chemical Industry. Many aspects of equipment design and operation are influenced by the choice of the alloys used to fabricate process equipment.

  13. Semiconductor Alloy Theory.

    DTIC Science & Technology

    1986-01-14

    ftoc*o~ow7 and Idenify’ by block nam. bor) Electron mobility , Lattice Relaxation, Bond Length, Bond Energy, Mixing Enthalpies, Band Structure, Core...including: (1) generalization of Brooks’ formula for alloy-scattering limited electron mobility to including multiple bands and indirect gaps, (2...calculation of SiGe alloys band structure, electron mobility and core-exciton binding energy and • :linewidth, (3) comprehensive calculation of bond

  14. PLUTONIUM-URANIUM ALLOY

    DOEpatents

    Coffinberry, A.S.; Schonfeld, F.W.

    1959-09-01

    Pu-U-Fe and Pu-U-Co alloys suitable for use as fuel elements tn fast breeder reactors are described. The advantages of these alloys are ease of fabrication without microcracks, good corrosion restatance, and good resistance to radiation damage. These advantages are secured by limitation of the zeta phase of plutonium in favor of a tetragonal crystal structure of the U/sub 6/Mn type.

  15. Ultrahigh temperature intermetallic alloys

    SciTech Connect

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.

    1998-11-01

    A new family of Cr-Cr{sub 2}Ta intermetallic alloys based on Cr-(6--10)Ta (at.%) is under development for structural use in oxidizing environments in the 1,000-1,300 C (1,832--2,372 F) temperature range. Development objectives relate to high temperature strength and oxidation resistance and room temperature fracture toughness. The 1,200 C (2,192 F) strength goals have been met: yield and fracture strengths of 275 MPa (40 ksi) and 345 MPa (50 ksi), respectively, were achieved. Progress in attaining reasonable fracture toughness of Cr-Cr{sub 2}Ta alloys has been made; current alloys exhibit room-temperature values of about 10--12 MPa{radical}m (1.1 MPa{radical}m = 1 ksi{radical}in.). Oxidation rates of these alloys at 950 C (1,742 F) in air are in the range of those reported for chromia-forming alloys. At 1,100 C (2,012 F) in air, chromia volatility was significant but, nevertheless, no scale spallation and positive weight gains of 1--5 mg/cm{sup 2} have been observed during 120-h, 6-cycle oxidation screening tests. These mechanical and oxidative properties represent substantial improvement over Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr alloys previously developed.

  16. Lattice constant grading in the Al.sub.y Ga.sub.1-y As.sub.1-x Sb.sub.x alloy system

    DOEpatents

    Moon, Ronald L.

    1980-01-01

    Liquid phase epitaxy is employed to grow a lattice matched layer of GaAsSb on GaAs substrates through the compositional intermediary of the III-V alloy system AlGaAsSb which acts as a grading layer. The Al constituent reaches a peak atomic concentration of about 6% within the first 2.5 .mu.m of the transition layer, then decreases smoothly to about 1% to obtain a lattice constant of 5.74 A. In the same interval the equilibrium concentration of Sb smoothly increases from 0 to about 9 atomic percent to form a surface on which a GaAsSb layer having the desired energy bandgap of 1.1 ev for one junction of an optimized dual junction photolvoltaic device. The liquid phase epitaxy is accomplished with a step cooling procedure whereby dislocation defects are more uniformly distributed over the surface of growing layer.

  17. Lattice constant grading in the Al.sub.y Ca.sub.1-y As.sub.1-x Sb.sub.x alloy system

    DOEpatents

    Moon, Ronald L.

    1981-01-01

    Liquid phase epitaxy is employed to grow a lattice matched layer of GaAsSb on GaAs substrates through the compositional intermediary of the III-V alloy system AlGaAsSb which acts as a grading layer. The Al constituent reaches a peak atomic concentration of about 6% within the first 2.5.mu.m of the transition layer, then decreases smoothly to about 1% to obtain a lattice constant of 5.74 A. In the same interval the equilibrium concentration of Sb smoothly increases from 0 to about 9 atomic percent to form a surface on which a GaAsSb layer having the desired energy bandgap of 1.1 ev for one junction of an optimized dual junction photovoltaic device. The liquid phase epitaxy is accomplished with a step cooling procedure whereby dislocation defects are more uniformly distributed over the surface of the growing layer.

  18. (Si){sub 5-2y}(AlP){sub y} alloys assembled on Si(100) from Al-P-Si{sub 3} building units

    SciTech Connect

    Watkins, T.; Chizmeshya, A. V. G.; Kouvetakis, J.; Jiang, L.; Xu, C.; Smith, D. J.; Menendez, J.

    2012-01-09

    An original class of IV/III-V hybrid (Si){sub 5-2y}(AlP){sub y}/Si(100) semiconductors have been produced via tailored interactions of molecular P(SiH{sub 3}){sub 3} and atomic Al yielding tetrahedral ''Al-P-Si{sub 3}'' building blocks. Extensive structural, optical, and vibrational characterization corroborates that these units condense to assemble single-phase, monocrystalline alloys containing 60%-90% Si (y = 0.3-1.0) as nearly defect-free layers lattice-matched to Si. Spectroscopic ellipsometry and density functional theory band structure calculations indicate mild compositional bowing of the band gaps, suggesting that the tuning needed for optoelectronic applications should be feasible.

  19. The optical spectrum of ternary alloy BBi1-xAsx

    NASA Astrophysics Data System (ADS)

    Yalcin, Battal G.; Aslan, M.; Ozcan, M. H.; Rahnamaye Aliabad, H. A.

    2016-06-01

    Among the III-V semiconductors, boron BBi and BAs as well as their alloys have attracted both scientific and technological interest in recent years. We present a calculation of the structural, electronic and optical properties of ternary alloy BBi1-xAsx by means of the WIEN2k software package. The exchange-correlation potential is treated by the generalized gradient approximation (GGA) within the schema of Wu and Cohen. Also, we have used the modified Becke-Johnson (mBJ) formalism to improve the band gap results. All the calculations have been performed after geometry optimization. In this study, we have investigated structural properties such as the lattice constant (a0), bulk modulus (B0) and its pressure derivative (B‧), and calculated the electronic band structures of the studied materials. Accurate calculation of linear optical properties, such as real (ɛ 1) and imaginary (ɛ 2) dielectric functions, reflectivity (R), electron energy loss spectrum, absorption coefficient (α), refractive index (n) and sum rule (Neff) are investigated. Our obtained results for studied binary compounds, BBi and BAs, fairly coincide with other theoretical calculations and experimental measurements. According to the best of our knowledge, no experimental or theoretical data are presently available for the studied ternary alloy BBi1-xAsx (0 < x < 1). The role of electronic band structure calculation with regards to the linear optical properties of BBi1-xAsx is discussed. The effect of the spin-orbit interaction (SOI) is also investigated and found to be quite small.

  20. Palladium alloys for biomedical devices.

    PubMed

    Wataha, John C; Shor, Kavita

    2010-07-01

    In the biomedical field, palladium has primarily been used as a component of alloys for dental prostheses. However, recent research has shown the utility of palladium alloys for devices such as vascular stents that do not distort magnetic resonance images. Dental palladium alloys may contain minor or major percentages of palladium. As a minor constituent, palladium hardens, strengthens and increases the melting range of alloys. Alloys that contain palladium as the major component also contain copper, gallium and sometimes tin to produce strong alloys with high stiffness and relatively low corrosion rates. All current evidence suggests that palladium alloys are safe, despite fears about harmful effects of low-level corrosion products during biomedical use. Recent evidence suggests that palladium poses fewer biological risks than other elements, such as nickel or silver. Hypersensitivity to palladium alone is rare, but accompanies nickel hypersensitivity 90-100% of the time. The unstable price of palladium continues to influence the use of palladium alloys in biomedicine.

  1. Hot Microfissuring in Nickel Alloy

    NASA Technical Reports Server (NTRS)

    Thompson, R. G.; Nunes, A.

    1984-01-01

    Experiments in intergranular cracking of nickel alloy near solidus temperature discussed in contractor report. Purpose of investigation development of schedule for welding, casting, forging, or other processing of alloy without causing microfissuring.

  2. Selective dissolution in binary alloys

    NASA Astrophysics Data System (ADS)

    McCall, Carol Rene

    Corrosion is an important issue in the design of engineering alloys. De-alloying is an aspect of alloy corrosion related to the selective dissolution of one or more of the components in an alloy. The work reported herein focuses on the topic of de-alloying specific to single-phase binary noble metal alloy systems. The alloy systems investigated were gold-silver and gold-copper. The onset of a bulk selective dissolution process is typically marked by a critical potential whereby the more reactive component in the alloy begins dissolving from the bulk, leading to the formation of a bi-continuous solid-void morphology. The critical potential was investigated for the entire composition range of gold-silver alloys. The results presented herein include the formulation of an expression for critical potential as a function of both alloy and electrolyte composition. Results of the first investigation of underpotential deposition (UPD) on alloys are also presented herein. These results were implemented as an analytical tool to provide quantitative measurements of the surface evolution of gold during de-alloying. The region below the critical potential was investigated in terms of the compositional evolution of the alloy surface. Below the critical potential, there is a competition between the dissolution of the more reactive alloying constituent (either silver or copper) and surface diffusion of gold that serves to cover dissolution sites and prevent bulk dissolution. By holding the potential at a prescribed value below the critical potential, a time-dependent gold enrichment occurs on the alloy surface leading to passivation. A theoretical model was developed to predict the surface enrichment of gold based on the assumption of layer-by-layer dissolution of the more reactive alloy constituent. The UPD measurements were used to measure the time-dependent surface gold concentration and the results agreed with the predictions of the theoretical model.

  3. Tissue Response to Base-Metal Dental Alloys.

    DTIC Science & Technology

    RESPONSE(BIOLOGY), *CASTING ALLOYS, *BASE METAL, * DENTAL PROSTHESES, TISSUES(BIOLOGY), COMPATIBILITY, NICKEL ALLOYS, BERYLLIUM, DENTISTRY, CANCER, HISTOLOGY, DENTAL IMPLANTOLOGY , COBALT ALLOYS, CHROMIUM ALLOYS.

  4. Finding the Alloy Genome

    NASA Astrophysics Data System (ADS)

    Hart, Gus L. W.; Nelson, Lance J.; Zhou, Fei; Ozolins, Vidvuds

    2012-10-01

    First-principles codes can nowadays provide hundreds of high-fidelity enthalpies on thousands of alloy systems with a modest investment of a few tens of millions of CPU hours. But a mere database of enthalpies provides only the starting point for uncovering the ``alloy genome.'' What one needs to fundamentally change alloy discovery and design are complete searches over candidate structures (not just hundreds of known experimental phases) and models that can be used to simulate both kinetics and thermodynamics. Despite more than a decade of effort by many groups, developing robust models for these simulations is still a human-time-intensive endeavor. Compressive sensing solves this problem in dramatic fashion by automatically extracting the ``sparse model'' of an alloy in only minutes. This new paradigm to model building has enabled a new framework that will uncover, automatically and in a general way across the periodic table, the important components of such models and reveal the underlying ``genome'' of alloy physics.

  5. (NH{sub 4})[V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}]: A new mixed valence vanadium(III,IV) fluoro-arsenate with ferromagnetic interactions and electronic conductivity

    SciTech Connect

    Berrocal, Teresa

    2009-01-15

    A new mixed valence vanadium(III,IV) fluoro-arsenate compound, with formula (NH{sub 4})[V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}] and KTP structure-type, has been synthesized by mild hydrothermal techniques. The crystal structure has been solved from single crystal X-ray diffraction data in the Pna2{sub 1} orthorhombic space group. The unit-cell parameters are a=13.196(2) A, b=6.628(1) A and c=10.7379(7) A with Z=8. The final R factors were R1=0.0438 and wR2=0.0943 [all data]. The crystal structure consists of a three-dimensional framework formed by (V{sup III,IV}O{sub 4}F{sub 2}) octahedra and (AsO{sub 4}){sup 3-} tetrahedra arsenate oxoanions. The vanadium(III,IV) cations, from the (V{sup III,IV}O{sub 4}F{sub 2}) octahedra, are linked through the fluorine atoms giving rise to zigzag chains. The ammonium cations are located in the cavities of the structure compensating the anionic charge of the [V{sub 1-x}{sup III}V{sub x}{sup IV}(AsO{sub 4})F{sub 1-x}O{sub x}]{sup -} inorganic skeleton. The thermal stability limit of the phase is 345 deg. C, around to this temperature the ammonium cation and fluoride anion are lost. The IR spectrum shows the characteristic bands of the (NH{sub 4}){sup +} and (AsO{sub 4}){sup 3-} ions. Magnetic measurements indicate the existence of weak ferromagnetic interactions. Electronic conductivity, via a hopping mechanism, occurs with an activation energy of 0.66 eV. - Graphical abstract: Polyhedral view of the crystal structure of (NH{sub 4})[V{sup III}{sub 1-x}V{sup IV}{sub x}(AsO{sub 4})F{sub 1-x}O{sub x}].

  6. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  7. Aluminum alloys with improved strength

    NASA Technical Reports Server (NTRS)

    Deiasi, R.; Adler, P.

    1975-01-01

    Mechanical strength and stress corrosion of new BAR and 7050 alloys that include Zn instead of Cr have been studied and compared with those of 7075 aluminum alloy. Added mechanical strength of new alloys is attributed to finer grain size of 5 to 8 micrometers, however, susceptibility to stress corrosion attack is increased.

  8. PLUTONIUM-URANIUM-TITANIUM ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-07-28

    A plutonium-uranium alloy suitable for use as the fuel element in a fast breeder reactor is described. The alloy contains from 15 to 60 at.% titanium with the remainder uranium and plutonium in a specific ratio, thereby limiting the undesirable zeta phase and rendering the alloy relatively resistant to corrosion and giving it the essential characteristic of good mechanical workability.

  9. Semiconductor alloys - Structural property engineering

    NASA Technical Reports Server (NTRS)

    Sher, A.; Van Schilfgaarde, M.; Berding, M.; Chen, A.-B.

    1987-01-01

    Semiconductor alloys have been used for years to tune band gaps and average bond lengths to specific applications. Other selection criteria for alloy composition, and a growth technique designed to modify their structural properties, are presently considered. The alloys Zn(1-y)Cd(y)Te and CdSe(y)Te(1-y) are treated as examples.

  10. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H.

    1998-12-31

    This new handbook is the most comprehensive publication of engineering information on commercial magnesium alloys under one cover in the last sixty years. Prepared with the cooperation of the International Magnesium Association, it presents the industrial practices currently used throughout the world, as well as the properties of the products critical to their proper application. Contents include: general characteristics; physical metallurgy; melting, refining, alloying, recycling, and powder production; casting; heat treatment; forging, rolling, and extrusion; semisolid processing; forming; joining; cleaning and finishing; selection, application, and properties of grades and alloys; design considerations; mechanical behavior and wear resistance; fatigue and fracture-mechanics; high-temperature strength and creep; corrosion and stress-corrosion cracking; specification.

  11. Hydrogen in titanium alloys

    SciTech Connect

    Wille, G W; Davis, J W

    1981-04-01

    The titanium alloys that offer properties worthy of consideration for fusion reactors are Ti-6Al-4V, Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242S) and Ti-5Al-6Sn-2Zr-1Mo-Si (Ti-5621S). The Ti-6242S and Ti-5621S are being considered because of their high creep resistance at elevated temperatures of 500/sup 0/C. Also, irradiation tests on these alloys have shown irradiation creep properties comparable to 20% cold worked 316 stainless steel. These alloys would be susceptible to slow strain rate embrittlement if sufficient hydrogen concentrations are obtained. Concentrations greater than 250 to 500 wppm hydrogen and temperatures lower than 100 to 150/sup 0/C are approximate threshold conditions for detrimental effects on tensile properties. Indications are that at the elevated temperature - low hydrogen pressure conditions of the reactors, there would be negligible hydrogen embrittlement.

  12. Surface modification of high temperature iron alloys

    DOEpatents

    Park, J.H.

    1995-06-06

    A method and article of manufacture of a coated iron based alloy are disclosed. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700--1200 C to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy. 13 figs.

  13. Surface modification of high temperature iron alloys

    DOEpatents

    Park, Jong-Hee

    1995-01-01

    A method and article of manufacture of a coated iron based alloy. The method includes providing an iron based alloy substrate, depositing a silicon containing layer on the alloy surface while maintaining the alloy at a temperature of about 700.degree. C.-1200.degree. C. to diffuse silicon into the alloy surface and exposing the alloy surface to an ammonia atmosphere to form a silicon/oxygen/nitrogen containing protective layer on the iron based alloy.

  14. Si-Ge-Sn alloys with 1.0 eV gap for CPV multijunction solar cells

    SciTech Connect

    Roucka, Radek Clark, Andrew; Landini, Barbara

    2015-09-28

    Si-Ge-Sn ternary group IV alloys offer an alternative to currently used 1.0 eV gap materials utilized in multijunction solar cells. The advantage of Si-Ge-Sn is the ability to vary both the bandgap and lattice parameter independently. We present current development in fabrication of Si-Ge-Sn alloys with gaps in the 1.0 eV range. Produced material exhibits excellent structural properties, which allow for integration with existing III-V photovoltaic cell concepts. Time dependent room temperature photoluminescence data demonstrate that these materials have long carrier lifetimes. Absorption tunable by compositional changes is observed. As a prototype device set utilizing the 1 eV Si-Ge-Sn junction, single junction Si-Ge-Sn device and triple junction device with Si-Ge-Sn subcell have been fabricated. The resulting I-V and external quantum efficiency data show that the Si-Ge-Sn junction is fully functional and the performance is comparable to other 1.0 eV gap materials currently used.

  15. Systematic approach for simultaneously correcting the band-gap andp-dseparation errors of common cation III-V or II-VI binaries in density functional theory calculations within a local density approximation

    SciTech Connect

    Wang, Jianwei; Zhang, Yong; Wang, Lin-Wang

    2015-07-31

    We propose a systematic approach that can empirically correct three major errors typically found in a density functional theory (DFT) calculation within the local density approximation (LDA) simultaneously for a set of common cation binary semiconductors, such as III-V compounds, (Ga or In)X with X = N,P,As,Sb, and II-VI compounds, (Zn or Cd)X, with X = O,S,Se,Te. By correcting (1) the binary band gaps at high-symmetry points , L, X, (2) the separation of p-and d-orbital-derived valence bands, and (3) conduction band effective masses to experimental values and doing so simultaneously for common cation binaries, the resulting DFT-LDA-based quasi-first-principles method can be used to predict the electronic structure of complex materials involving multiple binaries with comparable accuracy but much less computational cost than a GW level theory. This approach provides an efficient way to evaluate the electronic structures and other material properties of complex systems, much needed for material discovery and design.

  16. (Defect studies in III-V thin film semiconductors)

    SciTech Connect

    Not Available

    1991-01-01

    Our primary research objective in 90/91 has been to continue studying misfit dislocation confinement by patterning substrates into mesas before the epitaxial growth of strained layers. This report presents progress for many of the areas of our research. (JL)

  17. Radiation Effects in III-V Nanowire Devices

    DTIC Science & Technology

    2016-09-01

    Al diffusion into the GaAs layers across the heterointerface activated by Si atoms which cause Al intermixing at doped AlGaAs/GaAs heterointerfaces...pound (lb) 4.535 924 × 10 –1 kilogram (kg) unified atomic mass unit (amu) 1.660 539 × 10 –27 kilogram (kg) pound-mass per cubic foot (lb ft –3...sacrificial AlGaAs layer that will be oxidized to provide the isolation from the substrate.  local area growth of a nanowire or top-down definition of

  18. Piezoelectricity and growth polarization in III-V nitrides

    NASA Astrophysics Data System (ADS)

    Tavernier, Philip Ross

    GaN, AlN and InN form a relatively new class of semiconductors being utilized for their direct wide bandgap and polarization effects. Novel transistors using only piezoelectric doping have already surpassed the power handling capabilities of traditional silicon transistors. GaN light emitting diodes and solid state lasers, sensitive to the effects of piezoelectric polarization, are rapidly proliferating for use in lighting and next generation optical storage devices. GaN and AIN sensors and MEMS devices using the strong piezoelectric coupling coefficients of these materials are slowly being introduced into communications and chemical sensing applications. Despite the importance of the piezoelectric effect in each of these devices, relatively little is known of the magnitude of the effect in GaN and AIN as measured experimentally. The present work seeks to develop an experimental method of measuring the piezoelectric effect in thin films of GaN and AIN. Using a stress pulse induced by the single shot of a Nd:YAG laser, substrates of polar GaAs and ZnO are subject to short duration loading which generates piezoelectric dipoles. The orientation and magnitude of these dipoles induces current flow in an external circuit which is measured as a function time. By comparing the magnitude of the current generated in this circuit and the applied stress, it is shown that the axial piezoelectric constant, e 33, can be determined. Extending the measurement technique to thin films of GaN and AIN on sapphire and silicon, we have observed the magnitude and orientation of the piezoelectric dipoles in these materials. A value of 0.45 C/m2 for e33 in GaN was determined. This work motivated a closer investigation of the polarity of GaN during crystal growth. The addition of Mg during MOCVD was found to cause a uniform inversion of the growth axis producing nitrogen terminated surfaces under certain growth conditions. Chemical-mechanical polishing of these surfaces with colloidal silica was found to produce smooth, damage free surfaces suitable for regrowth or additional processing. Growth of GaN and InGaN along the nitrogen polar direction was characterized by AFM, TEM, SIMS, x-ray, PL, and Hall measurements revealing surprisingly high quality material suitable for optical and electrical devices.

  19. Investigation of New Semiinsulating Behavior of III-V Compounds.

    DTIC Science & Technology

    1990-02-23

    Czochralski and horizontal Bridgman techniques and in epitaxial crystals prepared by liquid-phase electroepitaxy. By employing deep-level transient... Bridgman (HB) 5’’ tech- motivated by the speculation that vanadium-oxygen com- niques has also been reported. In the above studies the posi- plexes...liquid-encapsulated Czochralski, (HB) horizontal Bridgman . found within the GaAs energy gap. However, several auth- (LPEE) liquid-phase

  20. Carbon films grown from plasma on III-V semiconductors

    NASA Technical Reports Server (NTRS)

    Pouch, J. J.; Warner, J. D.; Liu, D. C.

    1985-01-01

    Dielectric carbon films were grown on n- and p-type GaAs and InP substrates using plasmas generated at 30 KHz from gaseous hydrocarbons. The effect of gas source, flow rate, and power on film growth were investigated. Methane and n-butane gases were utilized. The flow rate and power ranged from 30 to 50 sccm and 25 to 300 W, respectively. AES measurements show only carbon to be present in the films. The relative Ar ion sputtering rate (3 KeV) of carbon depends on the ratio power/pressure. In addition, the degree of asymmetry associated with the carbon-semiconductor interface is approximately power-independent. SIMS spectra indicate different H-C bonding configurations to be present in the films. Band gaps as high as 3.05 eV are obtained from optical absorption studies.

  1. Chemical beam epitaxy growth of III-V semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Mohummed Noori, Farah T.

    2013-12-01

    Indium- Arsenide (InAs) nanowires were grown in a high vacuum chemical beam epitaxy (CBE) unit on InAs(111) wafers substrates at 425-454°C. Two types of nanogold were used as orientation catalyst, 40nm and 80nm. The measurements were performed using scanning electron microscopy showed that uniform nanowires. The nanowires orient vertically in the InAs nanowire scanning electron microscopy of an array 80nm diameter InAs nanowire with length is in the range 0.5-1 μm and of an array 40nm diameter with length is in the range 0.3-0.7μm. The nanowire length with growth time shows that the linear increase of nanowires start to grow as soon as TMIn is available. The growth rate with temperature was studied.

  2. Free Surface Properties of III-V Compound Semiconductor Surfaces.

    DTIC Science & Technology

    1980-06-01

    Review of Modern Physics Vol. 42 #3 July 1980, p. 317. 2. A. Kahn, G. Cisneros, M. Bonn, P. Mark and C.B. Duke, Surface Science 71, 387 (1978). 3. A...Kahn, E. So, P. Mark , C.B. Duke, J. Vac. Sci. Technol. 15, 580 (1978). 4. R.J. Meyer, C.B. Duke, A. Paton, A. Kahn, E. So, P. Mark , Phys. Rev. B19 (1979...Yeh, J. Tsang, A. Kahn, P. Mark , Phys. Rev. (to be published). 7. E. So, Ph.D. Dissertation, Princeton University, Department of Electrical Engineering

  3. Characterization of Hydrogen Complex Formation in III-V Semiconductors

    SciTech Connect

    Williams, Michael D

    2006-09-28

    Atomic hydrogen has been found to react with some impurity species in semiconductors. Hydrogenation is a methodology for the introduction of atomic hydrogen into the semiconductor for the express purpose of forming complexes within the material. Efforts to develop hydrogenation as an isolation technique for AlGaAs and Si based devices failed to demonstrate its commercial viability. This was due in large measure to the low activation energies of the formed complexes. Recent studies of dopant passivation in long wavelength (0.98 - 1.55m) materials suggested that for the appropriate choice of dopants much higher activation energies can be obtained. This effort studied the formation of these complexes in InP, This material is extensively used in optoelectronics, i.e., lasers, modulators and detectors. The experimental techniques were general to the extent that the results can be applied to other areas such as sensor technology, photovoltaics and to other material systems. The activation energies for the complexes have been determined and are reported in the scientific literature. The hydrogenation process has been shown by us to have a profound effect on the electronic structure of the materials and was thoroughly investigated. The information obtained will be useful in assessing the long term reliability of device structures fabricated using this phenomenon and in determining new device functionalities.

  4. Routes for Efficiency Improvement in III-V Photovoltaics

    DTIC Science & Technology

    2012-05-17

    solar cells that are both highly efficient and durable, high performance cells , such as GaAs -based devices, can be made smaller (< 1 cm2...2 mm2, and 1 cm2) GaAs thin film solar cells . Without passivation, a decline in efficiency was observed (Fig. 3, blue markers) with decreasing cell ...Eisler, C.N., Atwater, H.A. “ GaAs Passivation with Trioctylphosphine Sulfide for Enhanced Solar Cell Efficiency and

  5. Optoelectronic III-V Heterostructures on SI Substrates

    DTIC Science & Technology

    1990-09-14

    December 1989. VI. PERSONNEL Gary Y. Robinson, Principal Investigator Mike J. Hafich, Research Associate Todd E. Crumbaker, Graduate Student, Ph.D...and G.E. Stillman, AppL. Phys. Let- 54, 1457 (1989). 7. M.A. Haase, M.A. Emmanuel , S.C. Smith,. U. Coleman, and G.E. Stillman, Appl. Phys. Lett. 50

  6. Vertical III-V nanowire device integration on Si(100).

    PubMed

    Borg, Mattias; Schmid, Heinz; Moselund, Kirsten E; Signorello, Giorgio; Gignac, Lynne; Bruley, John; Breslin, Chris; Das Kanungo, Pratyush; Werner, Peter; Riel, Heike

    2014-01-01

    We report complementary metal-oxide-semiconductor (CMOS)-compatible integration of compound semiconductors on Si substrates. InAs and GaAs nanowires are selectively grown in vertical SiO2 nanotube templates fabricated on Si substrates of varying crystallographic orientations, including nanocrystalline Si. The nanowires investigated are epitaxially grown, single-crystalline, free from threading dislocations, and with an orientation and dimension directly given by the shape of the template. GaAs nanowires exhibit stable photoluminescence at room temperature, with a higher measured intensity when still surrounded by the template. Si-InAs heterojunction nanowire tunnel diodes were fabricated on Si(100) and are electrically characterized. The results indicate a high uniformity and scalability in the fabrication process.

  7. III-V Heterojunction Structures and High Speed Devices

    DTIC Science & Technology

    1992-03-02

    L’s) with tuent bulk materials and in an increase varyTng primitive cell , consisting of m of the number of atoms per primitive and n monolayers of...and lattice dynamics of these (m+n) per primitive cell (20). The SL’s and for obtaining a detailed infor- (Si) (Ge)n [001) SL’s constitute five...the primitive cell for the SL’s is governed by the specific vAlues of m and n for each Sb-family Present address: Division of Physic,. being a series

  8. Ion Implantation in III-V Compound Semiconductors

    DTIC Science & Technology

    1984-09-01

    340 keV H + -0 Ga P  O UES-723-292 !:• (H o>ray *P-K X - rayO Ga-K X -ray iii! RBS * ..I -iO.. 0 10I to1. 01 • .0 -. I0 1 LI =i, O I 0 01 0.J 10...Identity by blo ," pume) Ion Implantation, GaAs, Hall effect, electrical resistivity, Rutherford Backscattering (RBS), channeling, Proton induced x -ray...Mebility (jH) upon Aiinealing Temperature (TA) for 1 X 101 /cm• Dose Samples of GaAs:Mg with Three Different Capping Methods 33 p 14 Dependence of Surface

  9. Novel compound semiconductor devices based on III-V nitrides

    SciTech Connect

    Pearton, S.J.; Abernathy, C.R.; Ren, F.

    1995-10-01

    New developments in dry and wet etching, ohmic contacts and epitaxial growth of Ill-V nitrides are reported. These make possible devices such as microdisk laser structures and GaAs/AlGaAs heterojunction bipolar transistors with improved InN ohmic contacts.

  10. High temperature surface degradation of III-V nitrides

    SciTech Connect

    Vartuli, C.B.; Pearton, S.J.; Abernathy, C.R.; MacKenzie, J.D.; Lambers, E.S.; Zolper, J.C.

    1996-05-01

    The surface stoichiometry, surface morphology and electrical conductivity of AlN, GaN, InN, InGaN and InAlN was examined at rapid thermal annealing temperatures up to 1,150 C. The sheet resistance of the AlN dropped steadily with annealing, but the surface showed signs of roughening only above 1,000 C. Auger Electronic Spectroscopy (AES) analysis showed little change in the surface stoichiometry even at 1,150 C. GaN root mean square (RMS) surface roughness showed an overall improvement with annealing, but the surface became pitted at 1,000 C, at which point the sheet resistance also dropped by several orders of magnitude, and AES confirmed a loss of N from the surface. The InN surface had roughened considerably even at 650 C, and scanning electron microscopy (SEM) showed significant degradation. In contrast to the binary nitrides the sheet resistance of InAlN was found to increase by {approximately} 10{sup 2} from the as grown value after annealing at 800 C and then remain constant up to 1,000 C, while that of InGaN increased rapidly above 700 C. The RMS roughness increased above 800 C and 700 C respectively for InAlN and InGaN samples. In droplets began to form on the surface at 900 C for InAlN and at 800 C for InGaN, and then evaporate at 1,000 C leaving pits. AES analysis showed a decrease in the N concentration in the top 500 {angstrom} of the sample for annealing {ge} 800 C in both materials.

  11. Thermodynamic and Kinetic Aspects of III/V Epitaxy

    DTIC Science & Technology

    1992-05-22

    a applications electroniques et optiques University of Utah Dept. of Materials Science & Engineering Salt Lake City, UT 84112 May 22, 1992... microscopic strain energy. The kinetic aspects of epitaxy are by far the most complex and, consequently, the least understood. We are beginning to understand

  12. Assembly of nanostructures in III-V semiconductor films

    NASA Astrophysics Data System (ADS)

    Lee-Feldman, Jennifer Y.

    In film growth, assembly of nanostructures allows precise placement and reliable dimensions for higher efficiency in devices. This work looks at two extremes of assembly: spontaneous assembly manipulated by experimental parameters and directed assembly by altering surface patterns. First we vary experimental procedures to change feature sizes, and then we directly assemble dots on patterned surfaces. The morphologies in these films are characterized and then reproduced. We examine two different strained material systems: mesa formation in 2 monolayer GaAs films on In0.53Ga0.47As/InP and quantum dots in 2 monolayer InAs films on GaAs. We employ focused ion beam (FIB) patterning on the latter system to direct the formation of quantum dots. When varying growth parameters in the GaAs films, the mesa-trench morphology shown by scanning tunneling microscopy images changes significantly. There is roughening and mesa narrowing at higher temperatures, and intermixing is confirmed by X-ray coherent Bragg rod analysis. We use a Ga adatom density model to correspond to step edge density to predict morphological trends. This shows the commonly used metric of VIII growth ratio is not applicable at low As growth rates because of roughening. In the second material system we grow InAs quantum dots on GaAs. Explorations of ex situ FIB patterning show the technique is not successful due to oxide desorption roughness. We instead use in vacuo FIB to successfully assemble quantum dots on FIB-irradiated holes. We vary growth conditions, irradiation dose, and periodicity to yield single or multiple quantum dots. Elastic kinetic Monte Carlo simulations help predict the number of dots at sites and show that dot nucleation begins within the hole walls. The simulations show agreement with multiple dots, but discrepancies arise because of the limited amount of intermixing and initial hole shape. We characterize the quantum dot shape and holes and attempt to reconcile the large range of sizes with our experiments. Photoluminescent structures grown from the FIB-patterned quantum dots are measured. Spatial mapping shows that the FIB decreases InAs quantum dot peaks. Transmission electron microscopy images indicate that the lowered emission is due to the presence of defects caused by FIB.

  13. Study of the Electronic Surface State of III - V Compounds

    DTIC Science & Technology

    1976-03-15

    possible reason for the variation in Ep pinning observed by different groups , because EF is very sensitive to small (« 1 monolayer) of oxygen, and... foming a SchPtt.y barrier or by s^l amounts of oxygen. East,nan and cpworkers ba.e ^ alsp reported now finding n-type 3-S’s without surface state

  14. Physics and Technology of III-V Pseudomorphic Structures

    DTIC Science & Technology

    1990-11-15

    GaAs and InAs 2. Experimental procedures 11 AS BEPC(oir) MOMBE InAs The experiments were performed in a modified 0 o0.9 0 .50.6 prototype Perkin-Elmer...compared. The MEE technique results in better luminescent and device properties for hi2h indium concentration in the active layer. 2. EXPERIMENTAL ...surface: (3) a 150A InGaAs channel. the thickness of which is kept constant throughout the experiment : (4) a top delta-doped region in an Al 0 .28Gao

  15. Enhancing Hole Mobility in III-V Semiconductors

    DTIC Science & Technology

    2012-05-21

    in the channel and also to check for any residual strain present in the metamorphic buffer as it absorbs the lattice mismatch with the GaAs substrate...Figure 10 shows the rocking curves near the (004) GaAs peak for sample A1 (with In0.41Ga0.59Sb chan- nel) and sample B1 (GaSb channel with...superlattice of (AlAs)x(AlSb)1x). The different peaks in the rocking curve for sample A1 (Figure 10(a)) correspond to the peak from the GaAs substrate, the

  16. Nonlinear Frequency Conversion in III-V Semiconductor Photonic Crystals

    DTIC Science & Technology

    2012-03-01

    polarizing beamsplitter, SPF : short pass filter, PD: photodiode. The incident light traces the red line into the cavity sample. The second harmonic...33 CCD HWP HWP NPBSOLSample Polarizer Laser PBS PD Monochromator SPF 720 730 740 750 760 770 0 10 20 30 40 50 Wavelength [nm] C o u n ts a. b. c...OL: objective lens, PBS: polarizing beamsplitter, SPF : short pass filter, PD: photodiode. The incident light traces the red line into the cavity

  17. Asiago eclipsing binaries program. III. V570 Persei

    NASA Astrophysics Data System (ADS)

    Tomasella, L.; Munari, U.; Cassisi, S.; Siviero, A.; Dallaporta, S.; Sordo, R.; Zwitter, T.

    2008-05-01

    The orbit and physical parameters of the previously unsolved double-lined eclipsing binary V570 Per, discovered by the Hipparcos satellite, were derived using high-resolution Echelle spectroscopy and B, V photoelectric photometry. The metallicity from χ2 analysis of the spectra is [ M/H]=+0.02±0.03, and reddening from interstellar NaI and KI absorption lines is EB-V=0.023±0.007. V570 Per is a well-detached system, with shallow eclipses (due to low orbital inclination) and no sign of chromospheric activity. The two components have masses of 1.449±0.006 and 1.350±0.006~M_⊙ and spectral types F3 and F5, respectively. They are both still within the main sequence band (T_1=6842±25 K, T_2=6562± 25 K from χ2 analysis, R_1=1.523±0.030, R_2=1.388± 0.019 R_⊙ derived by forcing the orbital solution to conform to the spectroscopic light ratio) and are dynamically relaxed to co-rotation with the orbital motion (V_rot,1,2 sin i=40 and 36 (±1) km s-1). The distance to V570 Per obtained from the orbital solution is 123 ±2 pc, in excellent agreement with the revised Hipparcos distance of 123±11 pc. The observed properties of V570 Per components were compared to available families of stellar evolutionary tracks and, in particular, to BaSTI models computed on purpose for exactly the observed masses and varied chemical compositions. This system is interesting since both components have their masses in the range where the efficiency of convective core overshooting has to decrease with the total mass as a consequence of the decreasing size of the convective core during the central H-burning stage. Our numerical simulations show that, in order to match all empirical constraints, a small but not null overshooting is required, with efficiencies of λ_OV=0.14 and 0.11 for the 1.449 and 1.350 M_⊙ components, respectively. This confirms the finding of Paper II on the similar system V505 Per. At the ≈0.8 Gyr age of the system, the element diffusion has reduced the surface metallicity of the models from the initial [ M/H]=+0.17 to [ M/H]=+0.02, in perfect agreement with the spectroscopically derived [ M/H]=+0.02± 0.03 value. Based mainly on data obtained with Asiago 1.82 m telescope. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/483/263

  18. The Performance of Advanced III-V Solar Cells

    NASA Technical Reports Server (NTRS)

    Mueller, Robert L.; Gaddy, Edward; Day, John H. (Technical Monitor)

    2002-01-01

    Test results show triple junction solar cells with efficiencies as high as 27% at 28C and 136.7 mw/sq cm. Triple junction cells also achieve up to 27.5% at -120 C and 5 mw/sq cm, conditions applicable to missions to Jupiter. Some triple junction cells show practically no degradation as a result of Low Intensity Low Temperature (LILT) effects, while others show some; this degradation can be overcome with minor changes to the cell design.

  19. [Update of breast cancer in Primary Care (III/V)].

    PubMed

    Álvarez Hernández, C; Vich Pérez, P; Brusint, B; Cuadrado Rouco, C; Díaz García, N; Robles Díaz, L

    2014-01-01

    Breast cancer is a prevalent disease with implications in all aspects of patientś life, therefore, family doctors must know this pathology in depth, in order to optimize the health care provided to these patients with the best available resources. This series of five articles on breast cancer is based on a review of the scientific literature of the last ten years. This third article will review the clinical context and the staging and prognostic factors of the disease. This summary report aims to provide a global, current and practical review about this problem, providing answers to family doctors and helping them to be by the patients for their benefit throughout their illness.

  20. Dispersive Phonon Imaging in Iii-V Semiconductors.

    NASA Astrophysics Data System (ADS)

    Hebboul, Saad Eddine

    Low-temperature transport properties of high-frequency acoustic phonons are investigated in GaAs, InSb, InP and InAs using the phonon-imaging technique. In this method, a focused laser beam provides a movable heat source on one side of a cooled crystal (<=q2 K). A single small phonon detector on the opposite face records the transmitted heat flux as a function of propagation direction. Ballistic phonons channel along directions in the crystal which are completely determined by the detailed shape of constant-energy surfaces in wavevector space. The resulting focusing patterns are characterized by sharp phonon caustics which are clearly identified from the continuous background due to scattered phonons. In the dispersive regime, where phonon wavelength is comparable to atomic spacing, the angular positions of these caustic lines are very sensitive to phonon frequency, thus providing a novel test for lattice dynamics theories. Experiments are performed with superconducting tunnel junctions and Al bolometers to probe both the high-frequency and low -frequency regimes, respectively. We find that large-k ballistic phonons give rise to distinct focusing patterns in all four types of crystals, with thicknesses varying between 0.4 and 0.8 mm. Due to isotope scattering in the bulk, tunnel-junction experiments yield well-defined caustic patterns with a dominant frequency given by the detector gap 2Delta. In InSb, where zone boundary frequencies are small (nu_ {TA} ~ 1.2 THz), the frequency dependence of the dispersive phonon focusing patterns are measured using PbTl (0.43, 0.59 THz) and PbBi (0.69, 0.73, 0.78, 0.82 THz) tunnel junction detectors. The results are interpreted with Monte Carlo calculations based on rigid, dipole, shell, and bond-charge models. Although each model yields satisfactory fits to the previously measured dispersion curves, the predicted patterns show remarkable differences in the caustic structures. This result underscores the utility of phonon imaging in providing new information about the elastic forces between atoms in crystals.

  1. Physics and Technology of III-V Pseudomorphic Structures

    DTIC Science & Technology

    1991-03-01

    otR1tstk 1- An 0^13 DAT E 4. -r ln- 90 -30 Sevt. 91 Physics and Technology of 111-V Pseudomorphic P613 Structures R&T#4 14s002 6. AUTHOR(S) I C.W. Tu 1...tightens its grip on the fiber optic cable. The able gain from I to 5 for the incoming signal from each of electrical RHEED signals leave the phototransistor...box via the two phototransistors. The variable gain allows match- BNC connectors, and the 15 V dc required by the pho- ing of the noise levels of the

  2. Passivation of III-V Compound Semiconductor Based Devices

    DTIC Science & Technology

    1993-11-29

    approximately 60 A/s. The AES, Rutherford Backscattering, FIIR and stress measurements were also carried out. This work was done in collaboration with Dr ...begun to collaborate with us on the project. A brief description of these projects are listed below: 8 a) HP Research Laboratory ( Drs . S. Camnitz, K. L...DC characterization of devices. b) University of California. Santa Barbara ( Drs . B. Young, L. A. Coldren and V. Malhotra): Passivation of GaAs-based

  3. Quinary metallic glass alloys

    DOEpatents

    Lin, X.; Johnson, W.L.

    1998-04-07

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3}K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf){sub a}(Al,Zn){sub b}(Ti,Nb){sub c}(Cu{sub x}Fe{sub y}(Ni,Co){sub z}){sub d} wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d{hor_ellipsis}y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  4. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong; Johnson, William L.

    1998-01-01

    At least quinary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise zirconium and/or hafnium in the range of 45 to 65 atomic percent, titanium and/or niobium in the range of 4 to 7.5 atomic percent, and aluminum and/or zinc in the range of 5 to 15 atomic percent. The balance of the alloy compositions comprise copper, iron, and cobalt and/or nickel. The composition is constrained such that the atomic percentage of iron is less than 10 percent. Further, the ratio of copper to nickel and/or cobalt is in the range of from 1:2 to 2:1. The alloy composition formula is: (Zr,Hf).sub.a (Al,Zn).sub.b (Ti,Nb).sub.c (Cu.sub.x Fe.sub.y (Ni,Co).sub.z).sub.d wherein the constraints upon the formula are: a ranges from 45 to 65 atomic percent, b ranges from 5 to 15 atomic percent, c ranges from 4 to 7.5 atomic percent, d comprises the balance, d.multidot.y is less than 10 atomic percent, and x/z ranges from 0.5 to 2.

  5. Microporosity in casting alloys.

    PubMed

    Lewis, A J

    1975-06-01

    Three series of tensile test pieces were produced using a nickel base partial denture casting alloy. For the first series induction heating was employed, for the second a resistance crucible, and for the third an oxy-acetylene torch. Samples from each series were sectioned longitudinally, mounted, polished and examined microscopically for evidence of microporosity.

  6. Superplasticity in aluminum alloys

    SciTech Connect

    Nieh, T. G.

    1997-12-01

    We have characterized in the Al-Mg system the microstructure and mechanical properties of a cold-rolled Al-6Mg-0.3Sc alloy. The alloy exhibited superplasticity at relatively high strain rates (about 10-2 s-1). At a strain rate of 10-2 s-1 there exists a wide temperature range (475-520`C) within which the tensile elongation is over 1000%. There also exists a wide strain rate range (10-3 - 10-1 s-1) within which the tensile elongation is over 500%. The presence of Sc in the alloy results in a uniform distribution of fine coherent Al3SC precipitates which effectively pin grain and subgrain boundaries during static and continuous recrystallization. As a result, the alloy retains its fine grain size (about 7 micron), even after extensive superplastic deformation (>1000%). During deformation, dislocations Mg with a high Schmidt factor slip across subgrains but are trapped by subgrain boundaries, as a result of the strong pining of Al3Sc. This process leads to the conversion of low-angled subgrain boundaries to high-angled grain boundaries and the subsequent grain boundary sliding, which produces superelasticity. A model is proposed to describe grain boundary sliding accommodated by dislocation glide across grains with a uniform distribution of coherent precipitates. The model predictions is consistent with experimental observations.

  7. Shape Memory Alloy Actuator

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert J. (Inventor)

    2002-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  8. Shape Memory Alloy Actuator

    NASA Technical Reports Server (NTRS)

    Baumbick, Robert J. (Inventor)

    2000-01-01

    The present invention discloses and teaches a unique, remote optically controlled micro actuator particularly suitable for aerospace vehicle applications wherein hot gas, or in the alternative optical energy, is employed as the medium by which shape memory alloy elements are activated. In gas turbine powered aircraft the source of the hot gas may be the turbine engine compressor or turbine sections.

  9. Mechanical alloying of brittle materials

    NASA Astrophysics Data System (ADS)

    Davis, R. M.; McDermott, B.; Koch, C. C.

    1988-12-01

    Mechanical alloying by high energy ball milling has been observed in systems with nominally brittle components. The phases formed by mechanical alloying of brittle components include solid solutions (Si + Ge → SiGe solid solution), intermetallic compounds (Mn + Bi → MnBi), and amorphous alloys (NiZr2 + Ni11Zr9 → amorphous Ni50Zr50). A key feature of possible mechanisms for mechanical alloying of brittle components is the temperature of the powders during milling. Experiments and a computer model of the kinetics of mechanical alloying were carried out in order to esti-mate the temperature effect. Temperature rises in typical powder alloys during milling in a SPEX mill were estimated to be ≤350 K using the kinetic parameters determined from the computer model. The tempering response of fresh martensite in an Fe-1.2 wt pct C alloy during milling was consistent with the maximum results of the computer model, yielding temperatures in the pow-ders of ≤575 K i.e., ΔT ≤ 300 K). Thermal activation was required for mechanical alloying of Si and Ge powder. No alloying occurred when the milling vial was cooled by liquid nitrogen. The pos-sible mechanisms responsible for material transfer during mechanical alloying of brittle components are considered.

  10. Grindability of dental magnetic alloys.

    PubMed

    Hayashi, Eisei; Kikuchi, Masafumi; Okuno, Osamu; Kimura, Kohei

    2005-06-01

    In this study, the grindability of cast magnetic alloys (Fe-Pt-Nb magnetic alloy and magnetic stainless steel) was evaluated and compared with that of conventional dental casting alloys (Ag-Pd-Au alloy, Type 4 gold alloy, and cobalt-chromium alloy). Grindability was evaluated in terms of grinding rate (i.e., volume of metal removed per minute) and grinding ratio (i.e., volume ratio of metal removed compared to wheel material lost). Solution treated Fe-Pt-Nb magnetic alloy had a significantly higher grinding rate than the aged one at a grinding speed of 750-1500 m x min(-1). At 500 m x min(-1), there were no significant differences in grinding rate between solution treated and aged Fe-Pt-Nb magnetic alloys. At a lower speed of 500 m x min(-1) or 750 m x min(-1), it was found that the grinding rates of aged Fe-Pt-Nb magnetic alloy and stainless steel were higher than those of conventional casting alloys.

  11. Advanced ordered intermetallic alloy deployment

    SciTech Connect

    Liu, C.T.; Maziasz, P.J.; Easton, D.S.

    1997-04-01

    The need for high-strength, high-temperature, and light-weight materials for structural applications has generated a great deal of interest in ordered intermetallic alloys, particularly in {gamma}-based titanium aluminides {gamma}-based TiAl alloys offer an attractive mix of low density ({approximately}4g/cm{sup 3}), good creep resistance, and high-temperature strength and oxidation resistance. For rotating or high-speed components. TiAl also has a high damping coefficient which minimizes vibrations and noise. These alloys generally contain two phases. {alpha}{sub 2} (DO{sub 19} structure) and {gamma} (L 1{sub 0}), at temperatures below 1120{degrees}C, the euticoid temperature. The mechanical properties of TiAl-based alloys are sensitive to both alloy compositions and microstructure. Depending on heat-treatment and thermomechanical processing, microstructures with near equiaxed {gamma}, a duplex structure (a mix of the {gamma} and {alpha}{sub 2} phases) can be developed in TiAl alloys containing 45 to 50 at. % Al. The major concern for structural use of TiAl alloys is their low ductility and poor fracture resistance at ambient temperatures. The purpose of this project is to improve the fracture toughness of TiAl-based alloys by controlling alloy composition, microstructure and thermomechanical treatment. This work is expected to lead to the development of TiAl alloys with significantly improved fracture toughness and tensile ductility for structural use.

  12. Tungsten carbide laser alloying of a low alloyed steel

    NASA Astrophysics Data System (ADS)

    Cojocaru, Mihai; Taca, Mihaela

    1996-10-01

    Laser alloying is a way to change the composition of metal surfaces in order to improve their corrosion-resistance, high-temperature strength and hardness. The results of a structural and phase analysis of a tungsten carbide based surface layer prepared by laser alloying of a low carbon steel substrate are presented. Structure, phase composition and microhardness of surface alloyed layers have been investigated. The surface of the samples exhibited a thin layer with a different chemical and phase composition. An increase in alloyed surface hardness and wear-resistance was observed.

  13. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  14. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  15. DESIGN DATA STUDY FOR COATED COLUMBIUM ALLOYS

    DTIC Science & Technology

    ANTIOXIDANTS, * COATINGS , * NIOBIUM ALLOYS, *REFRACTORY COATINGS , *SILICON COATINGS , ALLOYS, ALUMINUM, DEFORMATION, ELASTIC PROPERTIES, HIGH...TEMPERATURE, OXIDATION, PLASTIC PROPERTIES, REENTRY VEHICLES, REFRACTORY MATERIALS, SHEETS, SILICIDES , VACUUM APPARATUS, VAPOR PLATING, ZIRCONIUM ALLOYS

  16. Materials data handbook, Inconel alloy 718

    NASA Technical Reports Server (NTRS)

    Sessler, J.; Weiss, V.

    1967-01-01

    Materials data handbook on Inconel alloy 718 includes data on the properties of the alloy at cryogenic, ambient, and elevated temperatures and other pertinent engineering information required for the design and fabrication of components and equipment utilizing this alloy.

  17. Two phase titanium aluminide alloy

    DOEpatents

    Deevi, Seetharama C.; Liu, C. T.

    2001-01-01

    A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

  18. TERNARY ALLOY-CONTAINING PLUTONIUM

    DOEpatents

    Waber, J.T.

    1960-02-23

    Ternary alloys of uranium and plutonium containing as the third element either molybdenum or zirconium are reported. Such alloys are particularly useful as reactor fuels in fast breeder reactors. The alloy contains from 2 to 25 at.% of molybdenum or zirconium, the balance being a combination of uranium and plutonium in the ratio of from 1 to 9 atoms of uranlum for each atom of plutonium. These alloys are prepared by melting the constituent elements, treating them at an elevated temperature for homogenization, and cooling them to room temperature, the rate of cooling varying with the oomposition and the desired phase structure. The preferred embodiment contains 12 to 25 at.% of molybdenum and is treated by quenching to obtain a body centered cubic crystal structure. The most important advantage of these alloys over prior binary alloys of both plutonium and uranium is the lack of cracking during casting and their ready machinability.

  19. Titanium-tantalum alloy development

    SciTech Connect

    Cotton, J.D.; Bingert, J.F.; Dunn, P.S.; Butt, D.P.; Margevicius, R.W.

    1996-04-01

    Research has been underway at Los Alamos National Laboratory for several years to develop an alloy capable of containing toxic materials in the event of a fire involving a nuclear weapon. Due to their high melting point, good oxidation resistance, and low solubility in molten plutonium, alloys based on the Ti-Ta binary system have been developed for this purpose. The course of the alloy development to-date, along with processing and property data, are presented in this overview.

  20. Characterization Techniques for Amorphous Alloys

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter '2 Characterization Techniques for Amorphous Alloys' with the content:

  1. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong; Merz, Martin D.

    1985-01-01

    Amorphous metal alloys of the iron-chromium and nickel-chromium type have excellent corrosion resistance and high temperature stability and are suitable for use as a protective coating on less corrosion resistant substrates. The alloys are stabilized in the amorphous state by one or more elements of titanium, zirconium, hafnium, niobium, tantalum, molybdenum, and tungsten. The alloy is preferably prepared by sputter deposition.

  2. Machine Casting of Ferrous Alloys.

    DTIC Science & Technology

    possible today. Extensive work was conducted on casting of semi-solid alloys when highly fluid (’ Rheocasting ’) and when thixotropically gelled...Thixocasting’). In initial phases of the program, copper base alloys and cast iron alloys were prepared with special non-dendritic Rheocast structure by batch...processing. Compatibility studies were carried out to select materials suitable for preparing cast iron with the Rheocast structure. Design

  3. Surface Segregation in Ternary Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo H.; Abel, Phillip B.

    2000-01-01

    Surface segregation profiles of binary (Cu-Ni, Au-Ni, Cu-Au) and ternary (Cu-Au-Ni) alloys are determined via Monte Carlo-Metropolis computer simulations using the BFS method for alloys for the calculation of the energetics. The behavior of Cu or Au in Ni is contrasted with their behavior when both are present. The interaction between Cu and Au and its effect on the segregation profiles for Cu-Au-Ni alloys is discussed.

  4. Alloy Interface Interdiffusion Modeled

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo H.; Garces, Jorge E.; Abel, Phillip B.

    2003-01-01

    With renewed interest in developing nuclear-powered deep space probes, attention will return to improving the metallurgical processing of potential nuclear fuels so that they remain dimensionally stable over the years required for a successful mission. Previous work on fuel alloys at the NASA Glenn Research Center was primarily empirical, with virtually no continuing research. Even when empirical studies are exacting, they often fail to provide enough insight to guide future research efforts. In addition, from a fundamental theoretical standpoint, the actinide metals (which include materials used for nuclear fuels) pose a severe challenge to modern electronic-structure theory. Recent advances in quantum approximate atomistic modeling, coupled with first-principles derivation of needed input parameters, can help researchers develop new alloys for nuclear propulsion.

  5. Shape memory alloy actuator

    DOEpatents

    Varma, Venugopal K.

    2001-01-01

    An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

  6. Duct and cladding alloy

    DOEpatents

    Korenko, Michael K.

    1983-01-01

    An austenitic alloy having good thermal stability and resistance to sodium corrosion at 700.degree. C. consists essentially of 35-45% nickel 7.5-14% chromium 0.8-3.2% molybdenum 0.3-1.0% silicon 0.2-1.0% manganese 0-0.1% zirconium 2.0-3.5% titanium 1.0-2.0% aluminum 0.02-0.1% carbon 0-0.01% boron and the balance iron.

  7. Nanocrystal dispersed amorphous alloys

    NASA Technical Reports Server (NTRS)

    Perepezko, John H. (Inventor); Allen, Donald R. (Inventor); Foley, James C. (Inventor)

    2001-01-01

    Compositions and methods for obtaining nanocrystal dispersed amorphous alloys are described. A composition includes an amorphous matrix forming element (e.g., Al or Fe); at least one transition metal element; and at least one crystallizing agent that is insoluble in the resulting amorphous matrix. During devitrification, the crystallizing agent causes the formation of a high density nanocrystal dispersion. The compositions and methods provide advantages in that materials with superior properties are provided.

  8. Full-zone k.p model for the electronic structure of unstrained GaAs1-xPx and strained AlxIn1-xAs alloys

    NASA Astrophysics Data System (ADS)

    Neffati, R.; Saïdi, I.; Boujdaria, K.

    2012-09-01

    We analyze the electronic energy band structure of strained and unstrained III-V semiconductors alloys within full-zone k.p approach in order to reach a realistic and minimal k.p model, parametrized to provide an accurate description of both valence and conduction bands. We show that a 40-band k.p model is fairly sufficient to reproduce accurately the overall band structure, obviating the use of any fictitious s* orbital. As an application, the 40-level k.p model is used to describe the band offsets as well as the band parameters in the strained AlxIn1-xAs/AlyGa1-yAs system.

  9. Radiation Effects in Refractory Alloys

    NASA Astrophysics Data System (ADS)

    Zinkle, Steven J.; Wiffen, F. W.

    2004-02-01

    In order to achieve the required low reactor mass per unit electrical power for space reactors, refractory alloys are essential due to their high operating temperature capability that in turn enables high thermal conversion efficiencies. One of the key issues associated with refractory alloys is their performance in a neutron irradiation environment. The available radiation effects data are reviewed for alloys based on Mo, W, Re, Nb and Ta. The largest database is associated with Mo alloys, whereas Re, W and Ta alloys have the least available information. Particular attention is focused on Nb-1Zr, which is a proposed cladding and structural material for the reactor in the Jupiter Icy Moons Orbiter (JIMO) project. All of the refractory alloys exhibit qualitatively similar temperature-dependent behavior. At low temperatures up to ~0.3TM, where TM is the melting temperature, the dominant effect of radiation is to produce pronounced radiation hardening and concomitant loss of ductility. The radiation hardening also causes a dramatic decrease in the fracture toughness of the refractory alloys. These low temperature radiation effects occur at relatively low damage levels of ~0.1 displacement per atom, dpa (~2×1024 n/m2, E>0.1 MeV). As a consequence, operation at low temperatures in the presence of neutron irradiation must be avoided for all refractory alloys. At intermediate temperatures (0.3 to 0.6 TM), void swelling and irradiation creep are the dominant effects of irradiation. The amount of volumetric swelling associated with void formation in refractory alloys is generally within engineering design limits (<5%) even for high neutron exposures (>>10 dpa). Very little experimental data exist on irradiation creep of refractory alloys, but data for other body centered cubic alloys suggest that the irradiation creep will produce negligible deformation for near-term space reactor applications.

  10. PLUTONIUM-CERIUM-COPPER ALLOYS

    DOEpatents

    Coffinberry, A.S.

    1959-05-12

    A low melting point plutonium alloy useful as fuel is a homogeneous liquid metal fueled nuclear reactor is described. Vessels of tungsten or tantalum are useful to contain the alloy which consists essentially of from 10 to 30 atomic per cent copper and the balance plutonium and cerium. with the plutontum not in excess of 50 atomic per cent.

  11. Shape memory alloy thaw sensors

    DOEpatents

    Shahinpoor, Mohsen; Martinez, David R.

    1998-01-01

    A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

  12. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

    Report is a summary of research work which has been done here and abroad on the constitution and mechanical properties of the various alloy systems with aluminum. The mechanical properties and compositions of commercial light alloys for casting, forging, or rolling, obtainable in this country are described.

  13. Equivalent crystal theory of alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1991-01-01

    Equivalent Crystal Theory (ECT) is a new, semi-empirical approach to calculating the energetics of a solid with defects. The theory has successfully reproduced surface energies in metals and semiconductors. The theory of binary alloys to date, both with first-principles and semi-empirical models, has not been very successful in predicting the energetics of alloys. This procedure is used to predict the heats of formation, cohesive energy, and lattice parameter of binary alloys of Cu, Ni, Al, Ag, Au, Pd, and Pt as functions of composition. The procedure accurately reproduces the heats of formation versus composition curves for a variety of binary alloys. The results are then compared with other approaches such as the embedded atom and lattice parameters of alloys from pure metal properties more accurately than Vegard's law is presented.

  14. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.; Gueceri, S. I.; Farkas, D.; Labdon, M. B.; Nagaswami, N.; Pregger, B.

    1981-01-01

    The feasibility of using metal alloys as thermal energy storage media was determined. The following major elements were studied: (1) identification of congruently transforming alloys and thermochemical property measurements; (2) development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients; (3) development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase change materials; and (4) identification of materials that could be used to contain the metal alloys. Several eutectic alloys and ternary intermetallic phases were determined. A method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase change media.

  15. Mo-Si alloy development

    SciTech Connect

    Liu, C.T.; Heatherly, L.; Wright, J.L.

    1996-06-01

    The objective of this task is to develop new-generation corrosion-resistant Mo-Si intermetallic alloys as hot components in advanced fossil energy conversion and combustion systems. The initial effort is devoted to Mo{sub 5}-Si{sub 3}-base (MSB) alloys containing boron additions. Three MSB alloys based on Mo-10.5Si-1.1B (wt %), weighing 1500 g were prepared by hot pressing of elemental and alloy powders at temperatures to 1600{degrees}C in vacuum. Microporosities and glassy-phase (probably silicate phases) formations are identified as the major concerns for preparation of MSB alloys by powder metallurgy. Suggestions are made to alleviate the problems of material processing.

  16. DEVELOPMENT OF PROTECTIVE COATINGS FOR TANTALUM-BASE ALLOYS

    DTIC Science & Technology

    PHASE STUDIES, PHYSICAL PROPERTIES, REFRACTORY MATERIALS, SILICIDES , SILICON COATINGS , SILICON COMPOUNDS, TANTALUM, TENSILE PROPERTIES, TITANIUM COMPOUNDS, TUNGSTEN ALLOYS, VANADIUM ALLOYS, VAPOR PLATING, ZINC COATINGS ....TANTALUM ALLOYS, ALLOYS, ALUMINUM COATINGS , ALUMINUM COMPOUNDS, BORON COMPOUNDS, CERAMIC COATINGS , CHROMIUM COMPOUNDS, COATINGS , FLAME SPRAYING...HAFNIUM ALLOYS, HAFNIUM COMPOUNDS, HARDNESS, HEAT RESISTANT ALLOYS, INTERMETALLIC COMPOUNDS, METAMATHEMATICS, NIOBIUM ALLOYS, OSCILLOGRAPHS, OXIDES

  17. Wedlable nickel aluminide alloy

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    2002-11-19

    A Ni.sub.3 Al alloy with improved weldability is described. It contains about 6-12 wt % Al, about 6-12 wt % Cr, about 0-3 wt % Mo, about 1.5-6 wt % Zr, about 0-0.02 wt % B and at least one of about 0-0.15 wt % C, about 0-0.20 wt % Si, about 0-0.01 wt % S and about 0-0.30 wt % Fe with the balance being Ni.

  18. Lightweight Disk Alloy Development

    DTIC Science & Technology

    1991-04-01

    2001 (1982). 45. K C. Russell and J. W Eddington , JI Mat. Sci., 6, 20 (1972). 46. M. J. Lequeux, Ph.D. Thesis, Univ. de Paris-Sud (1979). 47. P S ...AD-A237 064 UGHTWEIGHT DISK ALLOY DEVELOPMENT S . M. Russel, C. C. Law and M. J. Blackburn Uted Te lowkles Corpoaton Prat & Whtney Govnment Enes...Space Propulo P. 0. Box 109600 West Palm Beach, FL 33410-9600 P. C. Clapp and D. M. Pease Istitute of Materials Science 9 ELECT Fg AW 11il S E Final

  19. Thermomechanical treatment of alloys

    DOEpatents

    Bates, John F.; Brager, Howard R.; Paxton, Michael M.

    1983-01-01

    An article of an alloy of AISI 316 stainless steel is reduced in size to predetermined dimensions by cold working in repeated steps. Before the last reduction step the article is annealed by heating within a temperature range, specifically between 1010.degree. C. and 1038.degree. C. for a time interval between 90 and 60 seconds depending on the actual temperature. By this treatment the swelling under neutron bombardment by epithermal neutrons is reduced while substantial recrystallization does not occur in actual use for a time interval of at least of the order of 5000 hours.

  20. Stable palladium alloys for diffusion of hydrogen

    NASA Technical Reports Server (NTRS)

    Patapoff, M.

    1973-01-01

    Literature search on hydrogen absorption effect on palladium alloys revealed existence of alloy compositions in which alpha--beta transition does not take place. Survey conclusions: 40 percent gold alloy of palladium should be used in place of palladium; alloy must be free of interstitial impurities; and metallic surfaces of tube must be clean.

  1. Interaction Of Hydrogen With Metal Alloys

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Montano, J. W.

    1993-01-01

    Report describes experiments on interaction of hydrogen with number of metal alloys. Discusses relationship between metallurgical and crystallographic aspects of structures of alloys and observed distributions of hydrogen on charging. Also discusses effect of formation of hydrides on resistances of alloys to hydrogen. Describes attempt to correlate structures and compositions of alloys with their abilities to resist embrittlement by hydrogen.

  2. THEORY OF DIFFUSION IN ORDERING ALLOYS

    DTIC Science & Technology

    interstitial atoms through the interstices Diffusion of interstitial atoms in alloys with a body - centered cubic lattice Diffusion of...sites of the alloy The case of an alloy with body - centered cubic lattic structure The case of an alloy with a face-centered cubic lattic

  3. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

  4. Oxidation resistant alloys, method for producing oxidation resistant alloys

    DOEpatents

    Dunning, John S.; Alman, David E.

    2002-11-05

    A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

  5. Joint properties of cast Fe-Pt magnetic alloy laser welded to gold alloys.

    PubMed

    Watanabe, Ikuya; Nguyen, Khoi; Benson, P Andrew; Tanaka, Yasuhiro

    2006-01-01

    This study investigated the joint properties of a cast Fe-Pt magnetic alloy (Fe-36 at % Pt) laser welded to three gold alloys. The gold alloys used were ADA Type II and Type IV gold alloys, and an Ag-based (Ag-Au) gold alloy. Cast plates (0.5 x 3.0 x 10 mm) were prepared for each alloy. After the cast Fe-Pt plates were heat treated, they were butted against each of the three alloys and then laser welded with Nd:YAG laser at 200 V. Homogeneously welded specimens were also prepared for each alloy. Tensile testing was conducted at a crosshead speed of 1 mm/min. Failure load (N) and elongation (%) were recorded. After tensile testing, the fractured surfaces were examined with the use of SEM. The failure-load values of the group of alloys welded homogeneously were ranked in the order of: Ag-Au alloy > Type IV alloy > Type II alloy > Fe-Pt alloy. The Type IV alloy welded to Fe-Pt alloy had the highest failure-load value among the three alloys tested. The elongation results tended to follow a similar pattern. The results of this study indicated that Type IV gold alloy is a suitable alloy for metal frameworks to which cast Fe-Pt magnetic alloy is laser welded.

  6. High performance alloy electroforming

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Winkelman, D. M.

    1989-01-01

    Electroformed copper and nickel are used in structural applications for advanced propellant combustion chambers. An improved process has been developed by Bell Aerospace Textron, Inc. wherein electroformed nickel-manganese alloy has demonstrated superior mechanical and thermal stability when compared to previously reported deposits from known nickel plating processes. Solution chemistry and parametric operating procedures are now established and material property data is established for deposition of thick, large complex shapes such as the Space Shuttle Main Engine. The critical operating variables are those governing the ratio of codeposited nickel and manganese. The deposition uniformity which in turn affects the manganese concentration distribution is affected by solution resistance and geometric effects as well as solution agitation. The manganese concentration in the deposit must be between 2000 and 3000 ppm for optimum physical properties to be realized. The study also includes data regarding deposition procedures for achieving excellent bond strength at an interface with copper, nickel-manganese or INCONEL 718. Applications for this electroformed material include fabrication of complex or re-entry shapes which would be difficult or impossible to form from high strength alloys such as INCONEL 718.

  7. DISPERSION STRENGTHENED NICKEL-BASE ALLOYS.

    DTIC Science & Technology

    The swaged cone of extruded Nichrome-thoria alloys prepared by the thermal decomposition of thorium nitrate onto alloy powder indicated descreased... swaging of these dispersion-strengthened Nichrome alloys was dependent on the presence of a mild steel jacket on the alloy rod as a result of the canned...extrusion practice. Efforts to cold swage the alloy materials without this jacket were unsuccessful. (Author)

  8. Heat storage in alloy transformations

    NASA Technical Reports Server (NTRS)

    Birchenall, C. E.

    1980-01-01

    The feasibility of using metal alloys as thermal energy storage media was investigated. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases were determined. A new method employing X-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation. The method and apparatus are discussed and the experimental results are presented for aluminum and two aluminum-eutectic alloys. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide was identified as a promising containment material and surface-coated iron alloys were also evaluated. System considerations that are pertinent if alloy eutectics are used as thermal energy storage media are discussed. Potential applications to solar receivers and industrial furnaces are illustrated schematically.

  9. Mechanically Alloyed High Entropy Composite

    NASA Astrophysics Data System (ADS)

    Popescu, G.; Adrian, M. M.; Csaki, I.; Popescu, C. A.; Mitrică, D.; Vasile, S.; Carcea, I.

    2016-08-01

    In the last years high entropy alloys have been investigated due to their high hardness, high temperature stability and unusual properties that make these alloys to have significant interest. In comparison with traditional alloys that are based on two or three major elements, this new generation alloys consists at least of 5 principal elements, with the concentration between 5 and 35 at.%. The present paper reports synthesis of high entropy alloys (HEA) and high entropy composites (HEC) synthesized by mechanical alloying (MA). The equiatomic AlCrFeNiMn matrix was used for creating the HEA matrix, starting from elemental powders and as reinforcing material for composites was used pure graphite. The mechanical alloying process was carried out at different duration, in a high energy planetary ball mill, under argon atmosphere. The elemental powders alloying began after '5 hours of milling and was complete after 40 hours. The mechanical alloyed matrix and composite was pressed and heat treated under argon protection. The elemental powers were investigated for physical - technological properties, and by X-ray diffraction and scanning electron microscopy. Phase pressing operation was realized with a hydraulic press and the applied pressure was progressive. The sintering process was carried out at 850°C for 2 h. The X-ray diffraction revealed that the MA process resulted in solid solutions formation and also revealed body- centred cubic (BCC) and face-centred cubic (FCC) structures with average grain size around 40 nm. In addition, nanoscale particles were highlighted by scanning electron microscopy, as well as the homogeneity of the chemical composition of the matrix and composite that was confirmed by EDX microanalysis. It was noted that HEA matrix and HEA composites were processed with a high degree of compaction and with a quite large capacity of mixed powder densification (around 70%).

  10. Modeling dissolution in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Durbin, Tracie Lee

    2005-07-01

    Aluminum and its alloys are used in many aspects of modern life, from soda cans and household foil to the automobiles and aircraft in which we travel. Aluminum alloy systems are characterized by good workability that enables these alloys to be economically rolled, extruded, or forged into useful shapes. Mechanical properties such as strength are altered significantly with cold working, annealing, precipitation-hardening, and/or heat-treatments. Heat-treatable aluminum alloys contain one or more soluble constituents such as copper, lithium, magnesium, silicon and zinc that individually, or with other elements, can form phases that strengthen the alloy. Microstructure development is highly dependent on all of the processing steps the alloy experiences. Ultimately, the macroscopic properties of the alloy depend strongly on the microstructure. Therefore, a quantitative understanding of the microstructural changes that occur during thermal and mechanical processing is fundamental to predicting alloy properties. In particular, the microstructure becomes more homogeneous and secondary phases are dissolved during thermal treatments. Robust physical models for the kinetics of particle dissolution are necessary to predict the most efficient thermal treatment. A general dissolution model for multi-component alloys has been developed using the front-tracking method to study the dissolution of precipitates in an aluminum alloy matrix. This technique is applicable to any alloy system, provided thermodynamic and diffusion data are available. Treatment of the precipitate interface is explored using two techniques: the immersed-boundary method and a new technique, termed here the "sharp-interface" method. The sharp-interface technique is based on a variation of the ghost fluid method and eliminates the need for corrective source terms in the characteristic equations. In addition, the sharp-interface method is shown to predict the dissolution behavior of precipitates in aluminum

  11. Alloy design for intrinsically ductile refractory high-entropy alloys

    NASA Astrophysics Data System (ADS)

    Sheikh, Saad; Shafeie, Samrand; Hu, Qiang; Ahlström, Johan; Persson, Christer; Veselý, Jaroslav; Zýka, Jiří; Klement, Uta; Guo, Sheng

    2016-10-01

    Refractory high-entropy alloys (RHEAs), comprising group IV (Ti, Zr, Hf), V (V, Nb, Ta), and VI (Cr, Mo, W) refractory elements, can be potentially new generation high-temperature materials. However, most existing RHEAs lack room-temperature ductility, similar to conventional refractory metals and alloys. Here, we propose an alloy design strategy to intrinsically ductilize RHEAs based on the electron theory and more specifically to decrease the number of valence electrons through controlled alloying. A new ductile RHEA, Hf0.5Nb0.5Ta0.5Ti1.5Zr, was developed as a proof of concept, with a fracture stress of close to 1 GPa and an elongation of near 20%. The findings here will shed light on the development of ductile RHEAs for ultrahigh-temperature applications in aerospace and power-generation industries.

  12. Mechanical alloying of biocompatible Co-28Cr-6Mo alloy.

    PubMed

    Sánchez-De Jesús, F; Bolarín-Miró, A M; Torres-Villaseñor, G; Cortés-Escobedo, C A; Betancourt-Cantera, J A

    2010-07-01

    We report on an alternative route for the synthesis of crystalline Co-28Cr-6Mo alloy, which could be used for surgical implants. Co, Cr and Mo elemental powders, mixed in an adequate weight relation according to ISO Standard 58342-4 (ISO, 1996), were used for the mechanical alloying (MA) of nano-structured Co-alloy. The process was carried out at room temperature in a shaker mixer mill using hardened steel balls and vials as milling media, with a 1:8 ball:powder weight ratio. Crystalline structure characterization of milled powders was carried out by X-ray diffraction in order to analyze the phase transformations as a function of milling time. The aim of this work was to evaluate the alloying mechanism involved in the mechanical alloying of Co-28Cr-6Mo alloy. The evolution of the phase transformations with milling time is reported for each mixture. Results showed that the resultant alloy is a Co-alpha solid solution, successfully obtained by mechanical alloying after a total of 10 h of milling time: first Cr and Mo are mechanically prealloyed for 7 h, and then Co is mixed in for 3 h. In addition, different methods of premixing were studied. The particle size of the powders is reduced with increasing milling time, reaching about 5 mum at 10 h; a longer time promotes the formation of aggregates. The morphology and crystal structure of milled powders as a function of milling time were analyzed by scanning electron microscopy and XR diffraction.

  13. Metallic alloy stability studies

    NASA Technical Reports Server (NTRS)

    Firth, G. C.

    1983-01-01

    The dimensional stability of candidate cryogenic wind tunnel model materials was investigated. Flat specimens of candidate materials were fabricated and cryo-cycled to assess relative dimensional stability. Existing 2-dimensional airfoil models as well as models in various stages of manufacture were also cryo-cycled. The tests indicate that 18 Ni maraging steel offers the greatest dimensional stability and that PH 13-8 Mo stainless steel is the most stable of the stainless steels. Dimensional stability is influenced primarily by metallurgical transformations (austenitic to martensitic) and manufacturing-induced stresses. These factors can be minimized by utilization of stable alloys, refinement of existing manufacturing techniques, and incorporation of new manufacturing technologies.

  14. High strength ferritic alloy

    DOEpatents

    Hagel, William C.; Smidt, Frederick A.; Korenko, Michael K.

    1977-01-01

    A high-strength ferritic alloy useful for fast reactor duct and cladding applications where an iron base contains from about 9% to about 13% by weight chromium, from about 4% to about 8% by weight molybdenum, from about 0.2% to about 0.8% by weight niobium, from about 0.1% to about 0.3% by weight vanadium, from about 0.2% to about 0.8% by weight silicon, from about 0.2% to about 0.8% by weight manganese, a maximum of about 0.05% by weight nitrogen, a maximum of about 0.02% by weight sulfur, a maximum of about 0.02% by weight phosphorous, and from about 0.04% to about 0.12% by weight carbon.

  15. Manufacturing of High Entropy Alloys

    NASA Astrophysics Data System (ADS)

    Jablonski, Paul D.; Licavoli, Joseph J.; Gao, Michael C.; Hawk, Jeffrey A.

    2015-07-01

    High entropy alloys (HEAs) have generated interest in recent years due to their unique positioning within the alloy world. By incorporating a number of elements in high proportion they have high configurational entropy, and thus they hold the promise of interesting and useful properties such as enhanced strength and phase stability. The present study investigates the microstructure of two single-phase face-centered cubic (FCC) HEAs, CoCrFeNi and CoCrFeNiMn, with special attention given to melting, homogenization and thermo-mechanical processing. Large-scale ingots were made by vacuum induction melting to avoid the extrinsic factors inherent in small-scale laboratory button samples. A computationally based homogenization heat treatment was applied to both alloys in order to eliminate segregation due to normal ingot solidification. The alloys fabricated well, with typical thermo-mechanical processing parameters being employed.

  16. Technical Seminar "Shape Memory Alloys"

    NASA Video Gallery

    Shape memory alloys are a unique group of materials that remember their original shape and return to that shape after being strained. How could the aerospace, automotive, and energy exploration ind...

  17. Casting Characteristics of Aluminum Die Casting Alloys

    SciTech Connect

    Makhlouf M. Makhlouf; Diran Apelian

    2002-02-05

    The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

  18. Shape memory alloy thaw sensors

    DOEpatents

    Shahinpoor, M.; Martinez, D.R.

    1998-04-07

    A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states. 16 figs.

  19. Alloy dissolution in argon stirred steel

    NASA Astrophysics Data System (ADS)

    Webber, Darryl Scott

    Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I low carbon ferromanganese, nickel and tin (as a surrogate for low melting alloys) and Class II ferroniobium. The alloys ranged in size and form from granular to 30 mm diameter lumps. Experimental results were evaluated using a theoretically based numerical model for the steel shell period, alloy mixing (Class I) and alloy dissolution (Class II). A CFD model of the experimental ladle was used to understand steel motion in the ladle and to provide steel velocity magnitudes for the numerical steel shell model. Experiments and modeling confirmed that smaller sized alloys have shorter steel shell periods and homogenize faster than larger particles. Increasing the argon flow rate shortened mixing times and reduced the delay between alloy addition and the first appearance of alloy in the melt. In addition, for every five degree increase in steel bath temperature the steel shell period was shortened by approximately four percent. Class II ferroniobium alloy dissolution was an order of magnitude slower than Class I alloy mixing.

  20. Research and Development on Titanium Alloys

    DTIC Science & Technology

    1949-10-31

    svmym lIfe. Th~e rAnge of cOmposila Ivwstpted in the bin"rtniaum-stiver sistems was extended to 5% snw an M~an~Ajmm loy cntprn 0.1 Is beryllium were...extended to 5,0 per cent silverl and titanium- beryllium alloys containing 0.1 to-1.0 per cent berylliuma were inveitiga~ted. None of~ these alloys had...of: 1. Binary titanium-germanium alloys. 2. Binary titanium-nickel alloys. 3, Binary titanium-silver alloys. 4. Binary titanium- beryllium alloys. 5

  1. Choosing An Alloy For Automotive Stirling Engines

    NASA Technical Reports Server (NTRS)

    Stephens, Joseph R.

    1988-01-01

    Report describes study of chemical compositions and microstructures of alloys for automotive Stirling engines. Engines offer advantages of high efficiency, low pollution, low noise, and ability to use variety of fuels. Twenty alloys evaluated for resistance to corrosion permeation by hydrogen, and high temperature. Iron-based alloys considered primary candidates because of low cost. Nickel-based alloys second choice in case suitable iron-based alloy could not be found. Cobalt-based alloy included for comparison but not candidate, because it is expensive strategic material.

  2. Ni{sub 3}Al aluminide alloys

    SciTech Connect

    Liu, C.T.

    1993-10-01

    This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

  3. Alloy hardening and softening in binary molybdenum alloys as related to electron concentration

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Witzke, W. R.

    1972-01-01

    An investigation was conducted to determine the effects of alloy additions of hafnium, tantalum, tungsten, rhenium, osmium, iridium, and platinum on hardness of molybdenum. Special emphasis was placed on alloy softening in these binary molybdenum alloys. Results showed that alloy softening was produced by those elements having an excess of s+d electrons compared to molybdenum, while those elements having an equal number or fewer s+d electrons that molybdenum failed to produce alloy softening. Alloy softening and alloy hardening can be correlated with the difference in number of s+d electrons of the solute element and molybdenum.

  4. High strength forgeable tantalum base alloy

    NASA Technical Reports Server (NTRS)

    Buckman, R. W., Jr.

    1975-01-01

    Increasing tungsten content of tantalum base alloy to 12-15% level will improve high temperature creep properties of existing tantalum base alloys while retaining their excellent fabrication and welding characteristics.

  5. Imprinting bulk amorphous alloy at room temperature

    PubMed Central

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-01-01

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. Our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment. PMID:26563908

  6. Alloys developed for high temperature applications

    NASA Astrophysics Data System (ADS)

    Basuki, Eddy Agus; Prajitno, Djoko Hadi; Muhammad, Fadhli

    2017-01-01

    Alloys used for high temperatures applications require combinations of mechanical strength, microstructural stability and corrosion/oxidation resistance. Nickel base superalloys have been traditionally the prime materials utilized for hot section components of aircraft turbine engines. Nevertheless, due to their limited melting temperatures, alloys based on intermetallic compounds, such as TiAl base alloys, have emerged as high temperature materials and intensively developed with the main aim to replace nickel based superalloys. For applications in steam power plants operated at lower temperatures, ferritic high temperature alloys still attract high attention, and therefore, development of these alloys is in progress. This paper highlights the important metallurgical parameters of high temperature alloys and describes few efforts in the development of Fe-Ni-Al based alloys containing B2-(Fe,Ni)Al precipitates, oxide dispersion strengthening (ODS) ferritic steels and titanium aluminide based alloys include important protection system of aluminide coatings.

  7. Imprinting bulk amorphous alloy at room temperature

    SciTech Connect

    Kim, Song-Yi; Park, Eun-Soo; Ott, Ryan T.; Lograsso, Thomas A.; Huh, Moo-Young; Kim, Do-Hyang; Eckert, Jürgen; Lee, Min-Ha

    2015-11-13

    We present investigations on the plastic deformation behavior of a brittle bulk amorphous alloy by simple uniaxial compressive loading at room temperature. A patterning is possible by cold-plastic forming of the typically brittle Hf-based bulk amorphous alloy through controlling homogenous flow without the need for thermal energy or shaping at elevated temperatures. The experimental evidence suggests that there is an inconsistency between macroscopic plasticity and deformability of an amorphous alloy. Moreover, imprinting of specific geometrical features on Cu foil and Zr-based metallic glass is represented by using the patterned bulk amorphous alloy as a die. These results demonstrate the ability of amorphous alloys or metallic glasses to precisely replicate patterning features onto both conventional metals and the other amorphous alloys. In conclusion, our work presents an avenue for avoiding the embrittlement of amorphous alloys associated with thermoplastic forming and yields new insight the forming application of bulk amorphous alloys at room temperature without using heat treatment.

  8. Ab-initio DFT FP-LAPW GGA and LDA TB-mBJ and SO theoretical study of structural and elastic properties of Zinc-Blende crystal phase GaAs1-xBix alloys

    NASA Astrophysics Data System (ADS)

    Menezla, S.; Kadri, A.; Zitouni, K.; Djelal, A.; Djermouni, M.; Hallouche, A.; Zaoui, A.

    2015-12-01

    We present an ab-initio theoretical study of structural and elastic properties of GaAs1-xBix alloys in the Zinc-Blende (ZB) phase. We use a recent version of Wien2k package code based on Density Functional Theory (DFT) Full Potential and Linearized Augmented Plane Waves (FP-LAPW) method including recent Tran-Blaha modified Becke-Johnson correction of the exchange potential (TB-mBJ) and the spin-orbit interaction (SO). The calculations are performed within the Local Density Approximation (LDA) as well as the Generalized Gradient Approximation (GGA). We study first the structural properties of GaAs1-xBix alloys by solving Murnaghan equation of state. Our results show that the ZB phase is the lowest equilibrium crystal structure of GaAs1-xBix in the whole alloy composition range, in agreement with previous theoretical predictions. The variations versus Bi contents of the ZB GaAs1-xBix lattice constant a0, bulk modulus B0 and its pressure derivative B0‧ are also found very close to other theoretical and experimental data, but with much smaller bowing effects indicating a better resolution thanks to TB-mBJ correction. The variations of B0 versus the reverse equilibrium volume of the unit cell (1/V0) are found to be described by the simple linear empirical expression B0 = -0.21068 + 0.16695/V0 which is close to the theoretical prediction for III-V semiconductors with, however, somewhat lower linear coefficients values, suggesting a more metallic behavior. In a second part of this work, we use Birch-Murnaghan approach to study the elastic properties of GaAs1-xBix alloys. The elastic stiffness coefficients, C11, C12 and C44, and their variations versus alloy composition were determined for ZB GaAs1-xBix alloy. Their values in GaAs and GaBi binary compounds are found in very good agreement with available experimental and/or theoretical data. Their variations in GaAs1-xBix alloy show a monotonic decrease with increasing Bi contents, indicating a softening behavior as is

  9. Shape memory alloys. Ultralow-fatigue shape memory alloy films.

    PubMed

    Chluba, Christoph; Ge, Wenwei; Lima de Miranda, Rodrigo; Strobel, Julian; Kienle, Lorenz; Quandt, Eckhard; Wuttig, Manfred

    2015-05-29

    Functional shape memory alloys need to operate reversibly and repeatedly. Quantitative measures of reversibility include the relative volume change of the participating phases and compatibility matrices for twinning. But no similar argument is known for repeatability. This is especially crucial for many future applications, such as artificial heart valves or elastocaloric cooling, in which more than 10 million transformation cycles will be required. We report on the discovery of an ultralow-fatigue shape memory alloy film system based on TiNiCu that allows at least 10 million transformation cycles. We found that these films contain Ti2Cu precipitates embedded in the base alloy that serve as sentinels to ensure complete and reproducible transformation in the course of each memory cycle.

  10. Tarnish of dental alloys by oral microorganisms.

    PubMed

    Vaidyanathan, T K; Vaidyanathan, J; Linke, H A; Schulman, A

    1991-11-01

    Five dental alloys, on exposure to blood and chocolate media with and without inoculated microorganisms, showed varying degrees of tarnish. The results indicated a composition-dependent tarnish behavior of alloys in microorganism-inoculated media, indicating a potential role for the oral microorganisms in inducing clinically observed tarnish of dental alloys. Actinomyces viscosus and periodontal pocket specimens show a similarity in their activity to induce tarnish in base metal-containing dental alloys.

  11. Nickel aluminide alloys with improved weldability

    DOEpatents

    Santella, Michael L.; Goodwin, Gene M.

    1995-05-09

    Weldable nickel aluminide alloys which are essentially free, if not entirely free, of weld hot cracking are provided by employing zirconium concentrations in these alloys of greater than 2.6 wt. % or sufficient to provide a substantial presence of Ni--Zr eutectic phase in the weld so as to prevent weld hot cracking. Weld filler metals formed from these so modified nickel aluminide alloys provide for crack-free welds in previously known nickel aluminide alloys.

  12. Nickel aluminide alloys with improved weldability

    DOEpatents

    Santella, M.L.; Goodwin, G.M.

    1995-05-09

    Weldable nickel aluminide alloys which are essentially free, if not entirely free, of weld hot cracking are provided by employing zirconium concentrations in these alloys of greater than 2.6 wt. % or sufficient to provide a substantial presence of Ni--Zr eutectic phase in the weld so as to prevent weld hot cracking. Weld filler metals formed from these so modified nickel aluminide alloys provide for crack-free welds in previously known nickel aluminide alloys. 5 figs.

  13. HEAT TREATED U-Nb ALLOYS

    DOEpatents

    McGeary, R.K.; Justusson, W.M.

    1959-11-24

    A fuel element for a nuclear reactor is described comprising an alloy containing uranium and from 7 to 20 wt.% niobium, the alloy being substantially in the gamma phase and having been produced by working an ingot of the alloy into the desired shape, homogenizing it by annealing it at a temperature in the gamma phase field, and quenching it to retain the gamma phase structure of the alloy.

  14. Contact dermatitis from beryllium in dental alloys.

    PubMed

    Haberman, A L; Pratt, M; Storrs, F J

    1993-03-01

    An increasing number of metals with the potential to cause allergic contact dermatitis have found their way into dental alloys for economic and practical reasons. 2 patients are reported who developed gingivitis adjacent to the Rexillium III alloy in their dental prostheses. Patch testing demonstrated positive reactions to beryllium sulfate, a component of the alloy. Components of dental alloys and the mechanism of the contact dermatitis are discussed.

  15. Self-disintegrating Raney metal alloys

    DOEpatents

    Oden, Laurance L.; Russell, James H.

    1979-01-01

    A method of preparing a Raney metal alloy which is capable of self-disintegrating when contacted with water vapor. The self-disintegrating property is imparted to the alloy by incorporating into the alloy from 0.4 to 0.8 weight percent carbon. The alloy is useful in forming powder which can be converted to a Raney metal catalyst with increased surface area and catalytic activity.

  16. HIGH-TEMPERATURE OXIDATION PROTECTIVE COATINGS FOR VANADIUM-BASE ALLOYS

    DTIC Science & Technology

    SILICIDES , SILICON COATINGS , THIN FILM STORAGE DEVICES, TITANIUM ALLOYS, VAPOR PLATING, YTTRIUM COMPOUNDS, ZINC ALLOYS, ZINC COATINGS ....ANTIOXIDANTS, *METAL COATINGS , *REFRACTORY COATINGS , *VANADIUM ALLOYS, ALUMINUM ALLOYS, CERAMIC COATINGS , CHROMIUM ALLOYS, CLADDING, FLAME SPRAYING...HIGH TEMPERATURE, INTERMETALLIC COMPOUNDS, IODINE COMPOUNDS, IRON ALLOYS, MAGNESIUM ALLOYS, NICKEL ALLOYS, NICKEL COMPOUNDS, NIOBIUM ALLOYS, OXIDES

  17. Oxidation of low cobalt alloys

    NASA Technical Reports Server (NTRS)

    Barrett, C. A.

    1982-01-01

    Four high temperature alloys: U-700, Mar M-247, Waspaloy and PM/HIP U-700 were modified with various cobalt levels ranging from 0 percent to their nominal commercial levels. The alloys were then tested in cyclic oxidation in static air at temperatures ranging from 1000 to 1150 C at times from 500 to 100 1 hour cycles. Specific weight change with time and X-ray diffraction analyses of the oxidized samples were used to evaluate the alloys. The alloys tend to be either Al2O3/aluminate spinel or Cr2O3/chromite spinel formers depending on the Cr/Al ratio in the alloy. Waspaloy with a ratio of 15:1 is a strong Cr2O3 former while this U-700 with a ratio of 3.33:1 tends to form mostly Cr2O3 while Mar M-247 with a ratio of 1.53:1 is a strong Al2O3 former. The best cyclic oxidation resistance is associated with the Al2O3 formers. The cobalt levels appear to have little effect on the oxidation resistance of the Al2O3/aluminate spinel formers while any tendency to form Cr2O3 is accelerated with increased cobalt levels and leads to increased oxidation attack.

  18. Superconducting compounds and alloys research

    NASA Technical Reports Server (NTRS)

    Otto, G.

    1975-01-01

    Resistivity measurements as a function of temperature were performed on alloys of the binary material system In sub(1-x) Bi sub x for x varying between 0 and 1. It was found that for all single-phase alloys (the pure elements, alpha-In, and the three intermetallic compounds) at temperatures sufficiently above the Debye-temperature, the resistivity p can be expressed as p = a sub o T(n), where a sub o and n are composition-dependent constants. The same exponential relationship can also be applied for the sub-system In-In2Bi, when the two phases are in compositional equilibrium. Superconductivity measurements on single and two-phase alloys can be explained with respect to the phase diagram. There occur three superconducting phases (alpha-In, In2Bi, and In5Bi3) with different transition temperatures in the alloying system. The magnitude of the transition temperatures for the various intermetallic phases of In-Bi is such that the disappearance or occurrence of a phase in two component alloys can be demonstrated easily by means of superconductivity measurements.

  19. Quasicrystal-reinforced Mg alloys

    PubMed Central

    Kyun Kim, Young; Tae Kim, Won; Hyang Kim, Do

    2014-01-01

    The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg–Zn–Y and Mg–Zn–Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α-Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg–Zn–Y alloys, the co-presence of I and Ca2Mg6Zn3 phases by addition of Ca can significantly enhance formability, while in Mg–Zn–Al alloys, the co-presence of the I-phase and Mg2Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg–Zn–Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg–Zn–Al–Sn alloys is attributed to the presence of finely distributed Mg2Sn and I-phase particles embedded in the α-Mg matrix. PMID:27877660

  20. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    DOEpatents

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)