Sample records for gasb-based iii-v alloys

  1. Computational optical band gap bowing of III-V semiconductors alloys

    NASA Astrophysics Data System (ADS)

    Ferhat, M.

    2004-08-01

    A phenomenological model is described for the calculations of the optical band bowing of III-V semiconductor alloys. The optical band gap bowing is shown to account successfully for theoretical calculations and the experimental data.

  2. Electron transport in the III-V nitride alloys

    SciTech Connect

    Foutz, B.E.; O'Leary, S.K.; Shur, M.S.; Eastman, L.F.

    1999-07-01

    The authors study electron transport in the alloys of aluminum nitride and gallium nitride and alloys of indium nitride and gallium nitride. In particular, employing Monte Carlo simulations they determine the velocity-field characteristics associated with these alloys for various alloy compositions. They also determine the dependence of the low-field mobility on the alloy composition. They find that while the low-field mobility is a strong function of the alloy composition, the peak and saturation drift velocities exhibit a more mild dependence. Transient electron transport is also considered. They find that the velocity overshoot characteristic is a strong function of the alloy composition. The device implications of these results are discussed.

  3. On-line determination of alloy composition during ternary III/V molecular beam epitaxy

    SciTech Connect

    Tsao, J. Y.; Brennan, T. M.; Klem, J. F.; Hammons, B. E.

    1989-08-21

    We describe a simple, new method for deducing surface alloy composition during ternary III/V molecular beam epitaxy. The method is based on on-line reflection mass spectrometry of the group V flux ''reflected'' from the surface during momentary terminations of individual group III fluxes.

  4. Nuclear Magnetic Resonance Studies of II-Vi and Iii-V Semiconductor Alloys

    Microsoft Academic Search

    Jian-Hui Shi

    1993-01-01

    In this thesis, I show how the basic solid-state NMR techniques can be used to study the local electronic structures of II-VI and III-V semiconductor alloys on an atomic scale. We have focused our studies on a few high quality samples, mainly Hg_{rm 1-x}Cd_{rm x} Te in the II-VI group, In-based binary III-V bulk semiconductors InP, InAs and InSb, and

  5. On the importance of the band gap bowing in Boron-based III V ternary alloys

    NASA Astrophysics Data System (ADS)

    Azzi, S.; Zaoui, A.; Ferhat, M.

    2007-11-01

    The optical band gap bowing of eighteen III-V compound alloys containing boron is calculated by means of a recent phenomenological model [M. Ferhat, Phys. Status Solidi b 241 (2004) R38]. The optical band gap bowing is found to be strong for the all studied III-V boron alloys. In particular, we find that BNSb shows an important optical band gap bowing of 19.78 eV. Parallel to this, we also introduce ab initio pseudopotential plane wave calculations with large relaxed supercells to check the validity of our phenomenological model for BNSb. This gives an optical bowing of 21.19 eV, in fairly good agreement with the model used. Results suggest that the III-V boron alloys are characterized by a strong competition between the volume deformation (b), charge transfer (b), and structural relaxation (b) effects. For the common cation alloys b dominates b, and b is relatively weak; whereas for the common anion alloys, the structural effect ( b and b) appears to control the total optical band gap bowing.

  6. Progress in the growth and optical properties of dilute bismide III-V semiconductor alloys

    NASA Astrophysics Data System (ADS)

    Beaton, Daniel A.; Christian, T.; Lewis, R. B.; Alberi, K.; Mascarenhas, A.

    2015-03-01

    The dilute bismuth containing III-V semiconducting alloys of have great potential for application in many areas of semiconductor technology, such as multijunction photvoltaics and solid-state lighting. There is a large reduction of the fundamental bandgap of GaAs with bismuth incorporation resultant from the raising of the valence band maximum. Dilute bismide alloys have long been compared to the dilute nitride alloy because bismuth introduces a state near the valence band edge of the host GaAs (instrad of near the conduction band edge in the nitride alloys) that affects its optical and electronic properties. Here I will discuss some recent advances in our understanding of the surface processes involved in dilute bismide alloy growth by molecular beam epitaxy which have lead to improved film quality and the growth of new bismide alloys. The improved film quality has made it possible to further explore the properties of this material.

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

    DOEpatents

    Ciszek, Theodore F. (Evergreen, CO)

    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.

  8. Computer modeling study of monolithic three-junction solar cells composed of III-V ternary alloys

    Microsoft Academic Search

    H. C. Hamaker

    1985-01-01

    Monolithic three-junction solar cells composed of III-V ternary alloys have been studied using a computer model. InGaAs was used as the low-bandgap material, either AlGaAs or GaAsP was used as the high-bandgap material, and any of these alloys were used for the middle-bandgap junction. Tunnel junctions were assumed to electrically connect the subcells. The model included the losses resulting from

  9. Electronic structure of BAs and boride III-V alloys Gus L. W. Hart and Alex Zunger

    E-print Network

    Hart, Gus

    semiconductor alloys on common substrates such as GaAs, silicon, and germanium, semiconductor compounds, which of the wide gap semiconductor to shift the alloy band-gap to the red e.g., adding 1%­3% GaN to GaAs-III­V compounds. We find unexpected valence-band offsets of BAs with respect to GaAs and AlAs. The valence

  10. 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 strain plays in surface reconstructions will lead to a more complete understanding of the properties which govern reconstructions in general, and also create the possibility of engineering specific reconstructions which will form more abrupt interfaces, inject specific types of defects, or act as surfaces for subsequent self-assembly.

  11. Dilute nonisovalent (II-VI)-(III-V) semiconductor alloys: Monodoping, codoping, and cluster doping in ZnSe-GaAs

    Microsoft Academic Search

    L. G. Wang; Alex Zunger

    2003-01-01

    A dilute nonisovalent semiconductor alloy, made of a III-V semiconductor component (GaAs) mixed with a II-VI semiconductor (ZnSe), can be viewed as the doping of a host semiconductor with a lower (higher) valent cation and a higher (lower) valent anion. We have investigated different doping types, i.e., monodoping, triatomic codoping, and cluster doping, in the ZnSe-GaAs system using ab initio

  12. Persistent photoconductivity in II-VI and III-V semiconductor alloys and a novel infrared detector

    Microsoft Academic Search

    H. X. Jiang; G. Brown; J. Y. Lin

    1991-01-01

    Persistent photoconductivity (PPC) mechanisms, as well as the similarities and the differences of PPC properties in II-VI and III-V semiconductor alloys have been investigated. The potential applications based on PPC phenomenon in these two kinds of materials are discussed. We have observed that PPC induced in a II-VI mixed crystal by visible (above band gap) illumination can be quenched by

  13. Calculations of Optical Properties for Quaternary III-V Semiconductor Alloys in the Transparent Region and Above (0.2-4.0eV)

    E-print Network

    Rubloff, Gary W.

    for heterostructure lasers. Keywords: dielectric constant, compound semiconductors, optical properties, interband1 Calculations of Optical Properties for Quaternary III-V Semiconductor Alloys in the Transparent-V semiconductor alloys in the energy range from 0.2 to 4eV, including the transparent region, is presented

  14. Electron scattering by native defects in III-V nitrides and their alloys

    SciTech Connect

    Hsu, L. [Univ. of California, Berkeley, CA (United States). Department of Physics; Walukiewicz, W. [Univ. of California, Berkeley, CA (United States). Ernest Orlando Lawrence Berkeley National Laboratory

    1996-03-01

    We have calculated the electron mobilities in GaN and InN taking into consideration scattering by short range potentials, in addition to all standard scattering mechanisms. These potentials are produced by the native defects which are responsible for the high electron concentrations in nominally undoped nitrides. Comparison of the calculated mobilities with experimental data shows that scattering by short range potentials is the dominant mechanism limiting the electron mobilities in unintentionally doped nitrides with large electron concentrations. In the case of Al{sub x}Ga{sub 1-x}N alloys, the reduction in the electron concentration due to the upward shift of the conduction band relative to the native defect level can account for the experimentally measured mobilities. Resonant scattering is shown to be important when the defect and Fermi levels are close in energy.

  15. A review of energy bandgap engineering in III V semiconductor alloys for mid-infrared laser applications

    NASA Astrophysics Data System (ADS)

    Yin, Zongyou; Tang, Xiaohong

    2007-01-01

    Semiconductor lasers emitting in mid-infrared (IR) range, 2-5 ?m, have many important applications in semiconductor industries, military, environmental protection, telecommunications, molecular spectroscopy, biomedical surgery and researches. Different designs of the reactive regions in mid-IR laser structures have been investigated for achieving high performance devices. In this article, semiconductor mid-IR lasers with double heterostructure, quantum well, quantum cascade, quantum wire, quantum dash and quantum dot active regions have been reviewed. The performance of the lasers with these different active regions and the development of the newly emerging III-V-N materials for mid-IR applications have been discussed in details.

  16. 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.

  17. Persistent Photoconductivity in II-Vi and III -v Semiconductor Alloys and Exciton Dynamics in Semiconductor Quantum Dots

    Microsoft Academic Search

    Amal S. Dissanayake

    1994-01-01

    Persistent Photoconductivity (PPC) and time-resolved photoluminescence (PL) have been used to study the electrical transport properties and carrier dynamics in semiconductor alloys. PPC in Zn_{0.3}Cd _{0.7}Se, CdS_ {0.5}Se_{0.5} , Zn_{0.04}Cd _{0.96}Te, Al_{0.3 }Ga_{0.7}As, and SiC have been studied in this work. The PPC relaxation in Zn_{0.3}Cd _{0.7}Se and CdS_ {0.5}Se_{0.5} II-VI semiconductor alloys can be well described by the stretched

  18. Envelope Function Approximation (EFA) Bandstructure Calculations for III-V Non-square Stepped Alloy Quantum Wells Incorporating Ultra-narrow (˜5Å) Epitaxial Layers

    Microsoft Academic Search

    K. A. Kaduki; W. Batty

    2000-01-01

    We describe Envelope Function Approximation (EFA) bandstructure calculations based on a 4-band electron (EL), heavy-hole (HH), light-hole (LH) and split-off hole (SO) effective mass Hamiltonian, with Burt-Foreman hermitianisation, which can handle III-V quantum well structures that incorporate ultra-narrow epi-layers. The model takes into account the coupling of EL, HH, LH and SO bands and is suitable for describing quantum wells

  19. Thermodynamic analysis of the short-range clustering in III V solid solutions

    E-print Network

    Boyer, Edmond

    crystal growth technics. Phase diagrams, calculated from the limiting binary systems, are useful of III V phase diagrams : the authors [3] have shown the peculiar importance of this clustering tendency III V alloys. For alloys with two sites sublattices, this clustering tendency is introduced in each

  20. 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.

  1. Synthesis of III-V nitride nanowires with controlled structure, morphology, and composition

    E-print Network

    Crawford, Samuel Curtis

    2014-01-01

    The III-V nitride materials system offers tunable electronic and optical properties that can be tailored for specific electronic and optoelectronic applications by varying the (In,Ga,Al)N alloy composition. While nitride ...

  2. Thermoelectric figure of merit of (In0.53Ga0.47As)0.8(In0.52Al0.48As)0.2 III-V semiconductor alloys Je-Hyeong Bahk,1 Zhixi Bian,2 Mona Zebarjadi,2 Joshua M. O. Zide,3 Hong Lu,1,4 Dongyan Xu,5 Joseph P. Feser,5

    E-print Network

    recently for thermoelectric power generation as candidates to substitute SiGe in high- temperatureThermoelectric figure of merit of (In0.53Ga0.47As)0.8(In0.52Al0.48As)0.2 III-V semiconductor alloys manuscript received 15 April 2010; published 10 June 2010 The thermoelectric figure of merit is measured

  3. 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.

  4. Photodetectors using III-V nitrides

    DOEpatents

    Moustakas, Theodore D. (Dover, MA); Misra, Mira (Arlington, MA)

    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.

  5. 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.

  6. III-V Based Semiconductor THz Detectors

    Microsoft Academic Search

    A. G. U. Perera

    2006-01-01

    The III-V semiconductor materials have been investigated for use in the terahertz range, and results are reported on heterojunction and homojunction detectors. Broad response out to 1 THz has been observed in both Nitride and Antimonide based detectors. A responsivity R of ~2.5 AAV in 1-5 THz range was observed for a GaN detector. A stronger narrower response was also

  7. Reflection mass spectrometry (REMS) during III/V MBE

    SciTech Connect

    Tsao, J.Y.; Brennan, T.M.; Dawson, L.R.; Hammons, B.E.; Hibray, R.E.

    1990-01-01

    Reflection Mass Spectrometry (REMS) consists of a cryo-shrouded mass spectrometer which measures mass-analyzed, line-of-sight chemical fluxes from a growing wafer. It is especially useful during III/V molecular beam epitaxy (MBE) for which there are always substantial group V fluxes and often some group III fluxes leaving the wafer during growth. These fluxes depend sensitively on the instantaneous chemical reactivity of the surface. That chemical reactivity in turn depends on instantaneous alloy composition (III/III ratio), surface stoichiometry (As coverage) and temperature. In this brief summary of our work, we describe two examples of the engineering'' usefulness of REMS, involving MBE of InAlAs and InGaAs and one example of measurements of basic scientific interest. 3 figs.

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

    NASA Astrophysics Data System (ADS)

    Chizmeshya, Andrew; Kouvetakis, John

    2014-03-01

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

  9. Historical perspective on radiation effects in III-V devices

    Microsoft Academic Search

    Todd R. Weatherford

    2003-01-01

    A historical review of radiation effects on III-V semiconductor devices is presented. The discussion ranges from examining early material and device studies to present-day understanding of III-V radiation effects. The purpose of this paper is to provide present researchers with a summary of discoveries and lessons learned from previous failures and successes.

  10. III-V nanowires for optoelectronics

    NASA Astrophysics Data System (ADS)

    Kim, Yong; Gao, Q.; Joyce, H. J.; Tan, H. H.; Jagadish, C.; Paladugu, M.; Zou, J.

    2006-09-01

    The optical and structural properties of binary and ternary III-V nanowires including GaAs, InP, In(Ga)As, Al(Ga)As, and GaAs(Sb) nanowires by metal-organic chemical vapour deposition are investigated. Au colloidal nanoparticles are employed to catalyze nanowire growth. Zinc blende or wurtzite crystal structures with some stacking faults are observed for these nanowires by high resolution transmission electron microscope. In addition, the properties of heterostructure nanowires including GaAs-AlGaAs core-shell nanowires, GaAs-InAs nanowires, and GaAs-GaSb nanowires are reported. Single nanowire luminescence properties from optically bright InP nanowires are reported. Interesting phenomena such as two-temperature procedure, nanowire height enhancement of isolated ternary InGaAs nanowires, kinking effect of InAs-GaAs heterostructure nanowires, and unusual growth property of GaAs-GaSb heterostructure nanowires are investigated. These nanowires will play an essential role in future optoelectronic devices.

  11. 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 et al describe the transfer printing and bonding of III-V die on to CMOS wafers and Dastjerdi et al describe the optical performance of free-standing InGaAsP tube optical cavities which may be transferred to silicon substrates. Finally, describing important recent progress on GaN-based devices Jiang et al describe their work on InGaN light-emitting diodes on Si (1?1?1) substrates, Wallis et al describe similar structures with the emphasis on x-ray methods for the control of AlGaN buffer layer strain, Kumar et al describe low leakage current, large-area Schottky barrier photodetectors on Si, whilst Soltani et al describe their recent progress on AlGaN/GaN high electron mobility transistors grown on (1?0?0) and (1?1?0) silicon substrates. Overall, we think that this special issue of Semiconductor Science and Technology provides a timely overview of progress and the opportunities in this exciting and important field. Finally, we would like to thank the IOP editorial staff, in particular Alice Malhador, for their support, and we would also like to thank all contributors for their efforts in making this special issue possible.

  12. The prospects for 10 nm III-V CMOS

    E-print Network

    del Alamo, Jesus A.

    The increasing difficulties for further scaling down of Si CMOS is bringing to the fore the investigation of alternative channel materials. Among these, III-V compound semiconductors are very attractive due to their ...

  13. Advanced III-V Multijunction Cells for Space

    Microsoft Academic Search

    Richard R. King; Christopher M. Fetzer; Daniel C. Law; Kenneth M. Edmondson; Hojun Yoon; Geoffrey S. Kinsey; Dimitri D. Krut; James H. Ermer; Peter Hebert; B. Terence Cavicchi; Nasser H. Karam

    2006-01-01

    III-V solar cells have become the dominant power generation technology in space, due to their unparalleled high efficiency, reliability in the space environment, and ability to be integrated into very lightweight panels. As remarkable as these attributes are, new types of space III-V solar cells are continually reaching new heights in performance. Commercially-available multijunction solar cells with 30% conversion efficiency

  14. Projected performance of III-V epitaxial multijunction solar cells in space

    Microsoft Academic Search

    T. J. Maloney

    1981-01-01

    The monolithic epitaxial multijunction stack, to be fabricated from III-V quaternary alloys, has been analyzed for use in space with a detailed computer model. AlGaInAs and AlGaAsSb three-junction cells, each having an AlAsSb window, were modeled as functions of temperature, concentration, minority carrier diffusion length, etc., as were AlGaAs\\/GaAs and AlGaAsSb\\/InP two-junction cells. Cell efficiencies for one expected operating point

  15. Epitaxial growth and characterization of narrow bandgap III-V semiconductors and related semimetals

    NASA Astrophysics Data System (ADS)

    Choi, Sukgeun

    III-V semiconductors with the lattice spacing of 6.1A---GaSb, AlSb, InAs, and their heterostructures---offer great flexibility in designing novel solid-state devices via bandgap engineering. Despite of increasing interest, optical properties of these materials are still not well understood. In order to design and optimize device structures, knowledge of optical properties over a wide energy range is of importance. In this study, dielectric responses of AlxGa1- xSb (0.00 ? x ? 0.39) alloys, (GaSb) 3n(AlSb)n (1 ? n ? 5) superlattices, and InAsxP1-x (0.0 ? x ? 1.0) alloys have been determined by spectroscopic ellipsometry. Analysis of second-energy-derivatives calculated numerically from the measured data yielded the critical-point energies of the E1, E1+Delta1, E0', E2, and E 1' for both AlxGa1- xSb alloys and (GaSb)3n(AlSb) n superlattices while the E1, E1+Delta1, E0', E2, and E2+delta for InAs xP1-x alloys. Dependences of the critical-point energies on alloy composition and superlattice period have been obtained for the alloys and the superlattices, respectively. For the superlattice samples, two additional features were also observed near the E1+Delta1 critical-point structures for n ? 4. There is increasing interest in semimetallic rare-earth group-V compounds integrated into III-V semiconductor for potential applications in metal-base electronic devices, thermodynamically stable metallic contacts, and novel optoelectronic devices based on metallic nanoparticles. We have studied Sc xEr1-xSb compounds that grow epitaxially on the 6.1A family of III-V semiconductors. For the success of epitaxial growth of dissimilar materials, the ability of tailoring surfaces and interfaces on the atomic scale is required. This research focus, therefore, has been on understanding the initial growth nature of ErSb on GaSb(100). Results show that the initial nucleation of ErSb on GaSb(100) surfaces produces nanometer scale islands embedded within the surface of the GaSb. The growth is well represented by the embedded growth model in which islands nucleate in the surface of a substrate, grow laterally, and coalesce into a uniform film, and continue to grow in a layer-by-layer mode.

  16. Multi-junction solar cells based on the integration of II\\/VI and III\\/V semiconductors

    Microsoft Academic Search

    D. Ding; S.-N. Wu; S. Wang; S. R. Johnson; S.-Q. Yu; X. Liu; J. K. Furdyna; Y.-H. Zhang

    2008-01-01

    High-efficiency multifunction solar cells are attracting a great deal of attention for both space and terrestrial applications. We proposed the monolithic integration of the II\\/VI (ZnCdMg)(SeTe) and the III\\/V (InAlGa)(AsSb) material systems for multijunction solar cells. These material systems have direct bandgap, zinc blende, quaternary alloys, lattice-matched to GaSb substrates that cover the entire optical spectrum from greater than 3.0

  17. Projected performance of III-V epitaxial multijunction solar cells in space

    NASA Astrophysics Data System (ADS)

    Maloney, T. J.

    1981-05-01

    The monolithic epitaxial multijunction stack, to be fabricated from III-V quaternary alloys, has been analyzed for use in space with a detailed computer model. AlGaInAs and AlGaAsSb three-junction cells, each having an AlAsSb window, were modeled as functions of temperature, concentration, minority carrier diffusion length, etc., as were AlGaAs/GaAs and AlGaAsSb/InP two-junction cells. Cell efficiencies for one expected operating point in space (50 suns, 125 C) were around 20% for the two-junction cells and around 23-24% for the three-junction cells, using projected minority carrier diffusion lengths of 1.5 microns. Longer diffusion lengths in the III-V alloys (approaching those of GaAs) would allow the three-junction cells to reach 30% efficiency, if such conditions as 100 suns, 50 C can be achieved. The major technological challenges facing the high-efficiency multijunction cell are summarized and discussed in light of the modeling results.

  18. Research opportunities in crystalline III-V photovoltaics

    SciTech Connect

    Coutts, T.J. (National Renewable Energy Lab., Golden, CO (United States)); Lundstrom, M.S. (Purdue Univ., West Lafayette, IN (United States))

    1993-01-01

    Although III-V solar cells have been developed to a high level of performance, opportunities for fundamental advances still exist. For example, new structures could lead to substantial gains in conversion efficiency, multi-junction solar cells could achieve efficiencies well above 50%, and new materials could be developed for applications such as thermophotovoltaics. In this paper, the authors describe research opportunities that could provide the scientific base for substantial enhancements in the performance of crystalline III-V photovoltaic cells. 39 refs., 4 figs.

  19. 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.

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

    SciTech Connect

    Dutta, P.S.; Ostrogorsky, A.G.; Gutmann, R.J. [Rensselaer Polytechnic Inst., Troy, NY (United States)

    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.

  1. Analysis of germanium epiready wafers for III–V heteroepitaxy

    Microsoft Academic Search

    Ignacio Rey-Stolle; Enrique Barrigón; Beatriz Galiana; Carlos Algora

    2008-01-01

    Frequently, when growing III–V semiconductors on germanium substrates, unexpected differences between nominally identical substrates are encountered. Using atomic force microscopy (AFM), we have analysed a set of germanium substrates sharing the same specifications. The substrates come from the same vendor but different results come about in terms of the morphology of the epilayers produced by the same epitaxial routine (i.e.

  2. Calculating the generation function of III-V solar cells

    Microsoft Academic Search

    G. Letay; M. Breselge; A. W. Bett

    2003-01-01

    Modelling the electrical response of a III-V solar cell requires an exact knowledge of the distribution of photogenerated electron hole pairs G(z) within the solar cell structure. Also, this generation function, connects the optical with the electrical part of a solar cell model. In contrast to silicon solar cells, 99 % of the light is absorbed in the first few

  3. Characterization of III-V materials by optical interferometry

    Microsoft Academic Search

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

    1993-01-01

    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

  4. Extraordinary optoconductance in III-V metal semiconductor hybrid structures

    Microsoft Academic Search

    Kristopher Allen Wieland

    2007-01-01

    Extraordinary Optoconductance (EOC) is a measurement of the geometric enhancement to the opto- (or photo-) conductivity of a device. This dissertation elucidates the proof of principle of EOC using III-V semiconductor hybrids. For EOC two devices, identical save the addition of a metal shunt, are compared. The device without metal, referred to as the bare device or the unshunted device,

  5. Vibrational, mechanical, and thermal properties of III-V semiconductors

    Microsoft Academic Search

    John Dow

    1991-01-01

    Theories of the mechanical, vibrational, and electronic properties of III-V semiconductors were developed and applied to the following conditions. The physics were studies which underlie the II-VI doping problem and suggesting band gap engineering schemes for circumventing the problem. Predictions are made of how the character of deep and shallow impurities can be different in superlattices from in bulk materials.

  6. Electroluminescence imaging of III–V multijunction solar cells

    Microsoft Academic Search

    Claus G. Zimmermann

    2010-01-01

    The potential of electroluminescence imaging is demonstrated for large area III-V triple junction solar cells. The cells are modeled as two dimensional diode networks and the emitted electroluminescence under forward bias is used as a measure of the local voltage. Mechanical cell defects introduce a discontinuity in this network which is shown to result in a pronounced electroluminescence signature. This

  7. III-V material solar cells for space application

    Microsoft Academic Search

    T. V. Torchynska; G. P. Polupan

    2002-01-01

    The present paper is a review of current situation in space solar cell engineering. The comparison of the Si and III-V solar cell performances, as well as their parameter variation with temperature rise, radiation treatments and improving design were analyzed. The modern directions of the space solar cell development and international space projects, applied new types of solar cells, were

  8. Approaches for III/V Photonics on Si

    SciTech Connect

    Wiesner, M.; Schulz, W.-M.; Rossbach, R.; Jetter, M.; Michler, P. [Institut fuer Halbleiteroptik und Funktionelle Grenzflaechen, University of Stuttgart, Stuttgart, Germany and Stuttgart Research Center of Photonic Engineering (SCoPE) (Germany); Angelopoulos, E. A.; Burghartz, J. N. [Institut fuer Mikroelektronik Stuttgart (IMS CHIPS), Stuttgart (Germany); Werner, J.; Oehme, M.; Schulze, J. [Institut fuer Halbleitertechnik, University of Stuttgart, Germany and Stuttgart Research Center of Photonic Engineering (SCoPE) (Germany)

    2011-12-23

    We investigated different approaches to overcome difficulties in III/V-on-Si heteroepitaxy, namely growth on compliant substrates and virtual Ge substrates, both realized on top of Si substrates, and in addition, directly on Si. The prospect of this work was the realization of a light emitter on standard Si(100) substrate, capable of being integrated in established industrial processes.

  9. BAs-GaAs Semiconductor Alloys as a Photovoltaic Alternative to Nitride Alloys

    SciTech Connect

    Hart, G. L. W.; Zunger, A.

    2000-01-01

    Nitrogen alloyed III-V semiconductor compounds have been intensely studied in recent years due to unusual effects caused by nitrogen alloying. These effects are exploited in band gap engineering for specific applications such as solar cells and blue lasers.

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

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaaki; Ohya, Shinobu; Nam Hai, Pham

    2014-03-01

    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.

  11. Defect Analysis in III-V Semiconductor Thin Films Grown by Hydride Vapor Phase Epitaxy

    NASA Astrophysics Data System (ADS)

    Schulte, Kevin Louis

    Hydride vapor phase epitaxy (HVPE) is an epitaxial growth technique renowned for its ability to grow III-V semiconductors at high growth rates using lower cost reagents compared to metal-organic vapor phase epitaxy (MOVPE), the current industry standard. Recent interest in III-V photovoltaics has led to increased attention on HVPE. While the technique came to maturity in the 70s, much is unknown about how defects incorporate in HVPE-grown materials. Further understanding of how defects incorporate in III-V materials grown by HVPE is necessary to facilitate wider adoption of the technique. This information would inform strategies for minimizing and eliminating defects in HVPE materials, allowing for the formation of high performance devices. This investigation presents a study of multiple defects in III-V semiconductors grown by HVPE in the context of specific device applications, spanning point defects comprised of individual atoms to extended defects which propagate throughout the crystal. The incorporation of the arsenic anti-site defect, AsGa, intrinsic point defect was studied in high growth rate GaAs layers with potential photovoltaic applications. Relationships between growth conditions and incorporation of AsGa in GaAs epilayers were determined. The incorporation of AsGa depended strongly on the growth conditions employed, and a model was developed to predict the concentration of anti-site defects as a function of those growth conditions. Dislocations and anti-phase domain boundaries (APDBs), two types of extended defects, were investigated in the heteroepitaxial GaAs/Ge system. It was found that the use of 6° miscut substrates and specific growth temperatures led to elimination of APDBs. Dislocation densities were reduced through the use of high growth temperatures. The third and final application investigated was the growth of InxGa1-xAs metamorphic buffer layers (MBLs) by HVPE. The relationships between the growth conditions and the alloy composition were determined, and a model was developed to explain the observed behavior. Compositional grading strategies were explored and insight into the minimization of dislocations in these layers was developed. The dislocation microstructure was analyzed by TEM and related to the layer design, leading to the development of an atomic scale model for dislocation nucleation and propagation throughout the MBL layers.

  12. Large area III-V infrared focal planes

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Ting, D. Z.; Hill, C. J.; Nguyen, J.; Soibel, A.; Rafol, S. B.; Keo, S. A.; Mumolo, J. M.; Lee, M. C.; Liu, J. K.; Yang, B.; Liao, A.

    2011-05-01

    Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for remote sensing and imaging applications. Currently, we are working on Superlattice detectors, multi-band quantum well infrared photodetectors (QWIPs), and quantum dot infrared photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper, we will discuss the demonstration of long-wavelength 1 K × 1 K QDIP FPA, 1 K × 1K QWIP FPA, the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP FPA, and demonstration of the first mid-wave and long-wave 1K × 1K superlattice FPA. In addition, we will discuss the advantages of III-V material system in the context of large format infrared FPAs.

  13. III-V quantum dot enhanced photovoltaic devices

    Microsoft Academic Search

    David V. Forbes; Seth M. Hubbard; Christopher Bailey; Stephen Polly; John Andersen; Ryne Raffaelle

    2010-01-01

    State of the art photovoltaics exhibiting conversion efficiency in excess of 30% (1-sun) utilize epitaxially grown multijunction III-V materials. Increasing photovoltaic efficiency is critically important to the space power, and more recently, the terrestrial concentrator PV communities The use of nanostructured materials within photovoltaic devices can enable improved efficiency, potentially in excess of the Shockley-Queisser limit. The addition of nanostructures

  14. 5-junction III-V solar cells for space applications

    Microsoft Academic Search

    F. Dimroth; C. Baur; M. Meusel; S. van Riesen; A. W. Bett

    2003-01-01

    Monolithic multi-junction III-V solar cells with five active junctions, namely AlGaInP, GaInP, AlGaInAs, GaInAs and Ge have been realized for the first time. An open circuit voltage of 4826 mV was measured. The cells are expected to benefit of a superior radiation hardness as the thickness of each individual subcell is only in the range of 120-1600 nm. The measurement

  15. Extensible modelling framework for nanostructured III-V solar cells

    Microsoft Academic Search

    Markus F Fuhrer; Jessica G J Adams; Keith W J Barnham; Ben C Browne; Ngai L A Chan; Daniel J Farrell; Louise Hirst; Kan-Hua Lee; Ned J Ekins-Daukes; Akio Ogura; Katsuhisa Yoshida; Yoshitaka Okada

    2011-01-01

    The use of nanostructures has been shown to provide practical performance enhancements to high-efficiency III-V based solar cells by permitting sub-bandgap tuneable absorption. Nanostructures present a fertile ground for new solar cell technologies, and an improved understanding of fundamental processes may even lead to functional intermediate band and hot-carrier devices. As the fundamental processes occurring in nanostructured solar cells are

  16. Optically enhanced oxidation of III-V compound semiconductors

    Microsoft Academic Search

    Mitsuo Fukuda; Kenichiro Takahei

    1985-01-01

    Oxidation of III-V compound semiconductor (110) cleaved surfaces under light irradiation is studied. The light irradiation enhanced the reaction rate of oxidation but the relationship between oxide growth and oxidation time under logarithmic law scarcely changed within this experimental range. The oxidation trend observed under light irradiation is similar to that of thermal oxidation for GaP, GaAs, InP, InAs, InGaAs,

  17. Electrochemical Studies of Iii-V Semiconductor Liquid Interfaces

    Microsoft Academic Search

    Louis Gregory Casagrande

    1988-01-01

    Systematic trends in the behavior of stable n -type III-V semiconductor\\/liquid interfaces have been investigated. The properties of liquid junction solar cells constructed from these materials differed substantially from those of the corresponding metal interfaces. An open-circuit photovoltage of 830 millivolts and an optical-to-electrical conversion efficiency of 11% at simulated 1 Sun, AM1.5 conditions were observed for the n-gallium arsenide\\/acetonitrile-lithium

  18. ESTUDIO DE CELDAS SOLARES BASADAS EN MATERIALES III-V

    Microsoft Academic Search

    M. Barrera; J. Plá; F. Rubinelli

    RESUMEN: Los dispositivos fotovoltaicos basados en semicondu ctores III-V se utilizan como fuente de potencia de satélites y otros vehículos espaciales debido a su alta eficiencia y resistencia a la radiación. En pa rticular, los paneles solares de las próximas misiones satelitales argentinas con tarán con celdas de triple juntura, ATJ ( Advanced Triple Junction ) InGaP\\/GaAs\\/Ge fabricadas por la

  19. New phenomena in Schottky barrier formation on III V compounds

    Microsoft Academic Search

    I. Lindau; P. W. Chye; C. M. Garner; P. Pianetta; C. Y. Su; W. E. Spicer

    1978-01-01

    The possibility of a defect mechanism is proposed to explain the Fermi-level pinning in Schottky barriers on III--V semiconductor surfaces. This suggestion comes from the results of photoemission spectroscopy applied to the study of formation of metal--semiconductor barrier heights. Changes in the electronic structure and composition of the interface are studied. For Au metal overlayers on the (110) surfaces of

  20. III-V infrared research at the Jet Propulsion Laboratory

    Microsoft Academic Search

    S. D. Gunapala; D. Z. Ting; C. J. Hill; A. Soibel; John Liu; J. M. Mumolo; S. A. Keo; J. Nguyen; S. V. Bandara; M. Z. Tidrow

    2009-01-01

    Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for NASA, DoD, and commercial applications. Currently, we are working on multi-band Quantum Well Infrared Photodetectors (QWIPs), Superlattice detectors, and Quantum Dot Infrared Photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper we report

  1. Large area III–V infrared focal planes

    Microsoft Academic Search

    S. D. Gunapala; D. Z. Ting; C. J. Hill; J. Nguyen; A. Soibel; S. B. Rafol; S. A. Keo; J. M. Mumolo; M. C. Lee; J. K. Liu; B. Yang; A. Liao

    2011-01-01

    Jet Propulsion Laboratory is actively developing the III–V based infrared detector and focal plane arrays (FPAs) for remote sensing and imaging applications. Currently, we are working on Superlattice detectors, multi-band quantum well infrared photodetectors (QWIPs), and quantum dot infrared photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper, we will

  2. Record Performance III-V and III-V on Si Esaki Diodes Authors: S. L. Rommel1

    E-print Network

    Rommel, Sean

    -to- valley current ratio (PVCR) performance III-V tunnel diodes on a Si platform (67) and record peak current platform. Two latticed matched In0.53Ga0.47As Esaki tunnel diodes, TD2 (Fig. 4a) and TD3 (Fig. 4b), were of the authors, TD1 has the largest experimentally observed JP of any tunnel diode [7]. The tunneling current

  3. How do electronic properties of conventional III-V semiconductors hold for the III-V boron bismuth BBi compound?

    NASA Astrophysics Data System (ADS)

    Madouri, D.; Ferhat, M.

    2005-11-01

    We have performed ab-initio self-consistent calculations using the full potential linear augmented plane wave method to investigate the structural and the electronic properties of the boron bismuth III-V compound BBi. Our calculations provide the first available information about the structural and electronic ground-state properties of BBi. Total energy calculations of the cubic zinc-blende, wurtzite, rock-salt, cesium chloride and orthorhombic Cmcm phases are made. The zinc-blende structure is found to be the ground-state phase of BBi; within the generalized gradient approximation (local density approximation), we found a lattice constant of 5.529 Å (5.416 Å) and a bulk modulus of 72.20 GPa (86.27 GPa). We found that, contrary to other boron compounds, the band gap of BBi is direct at the point. The relativistic contraction of the 6s orbital of Bi has a strong influence on the bands and bonds of BBi. Consequently, the electronic properties of BBi are shown to differ considerably from those of common group III-V semiconductors (e.g. GaAs); in particular, we found an unusually strong p-p mixing of the valence-band maximum relative to most of the other III-V compounds. Furthermore, the calculated valence charge density shows an anomalous behavior, characterized by a charge transfer towards the cation' B atom, further illustrating the rich behavior of boron bismuth compounds.

  4. Ultrabright and ultrafast III-V semiconductor photocathodes.

    PubMed

    Karkare, Siddharth; Boulet, Laurent; Cultrera, Luca; Dunham, Bruce; Liu, Xianghong; Schaff, William; Bazarov, Ivan

    2014-03-01

    Crucial photoemission properties of layered III-V semiconductor cathodes are predicted using Monte Carlo simulations. Using this modeling, a layered GaAs structure is designed to reduce simultaneously the transverse energy and response time of the emitted electrons. This structure, grown by molecular beam epitaxy and activated to negative electron affinity, is characterized. The measured values of quantum efficiency and transverse energy are found to agree well with the simulations. Such advanced layered structures will allow generation of short electron bunches from photoinjectors with superior beam brightness. PMID:24655275

  5. Ultrabright and Ultrafast III-V Semiconductor Photocathodes

    NASA Astrophysics Data System (ADS)

    Karkare, Siddharth; Boulet, Laurent; Cultrera, Luca; Dunham, Bruce; Liu, Xianghong; Schaff, William; Bazarov, Ivan

    2014-03-01

    Crucial photoemission properties of layered III-V semiconductor cathodes are predicted using Monte Carlo simulations. Using this modeling, a layered GaAs structure is designed to reduce simultaneously the transverse energy and response time of the emitted electrons. This structure, grown by molecular beam epitaxy and activated to negative electron affinity, is characterized. The measured values of quantum efficiency and transverse energy are found to agree well with the simulations. Such advanced layered structures will allow generation of short electron bunches from photoinjectors with superior beam brightness.

  6. III-V Infrared Research at the Jet Propulsion Laboratory

    NASA Technical Reports Server (NTRS)

    Gunapala, S. D.; Ting, D. Z.; Hill, C. J.; Soibel, A.; Liu, John; Liu, J. K.; Mumolo, J. M.; Keo, S. A.; Nguyen, J.; Bandara, S. V.; Tidrow, M. Z.

    2009-01-01

    Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for NASA, DoD, and commercial applications. Currently, we are working on multi-band Quantum Well Infrared Photodetectors (QWIPs), Superlattice detectors, and Quantum Dot Infrared Photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper we report the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP focal plane array (FPA). In addition, we will present the latest advances in QDIPs and Superlattice infrared detectors at the Jet Propulsion Laboratory.

  7. III-V infrared research at the Jet Propulsion Laboratory

    NASA Astrophysics Data System (ADS)

    Gunapala, S. D.; Ting, D. Z.; Hill, C. J.; Soibel, A.; Liu, John; Liu, J. K.; Mumolo, J. M.; Keo, S. A.; Nguyen, J.; Bandara, S. V.; Tidrow, M. Z.

    2009-08-01

    Jet Propulsion Laboratory is actively developing the III-V based infrared detector and focal plane arrays (FPAs) for NASA, DoD, and commercial applications. Currently, we are working on multi-band Quantum Well Infrared Photodetectors (QWIPs), Superlattice detectors, and Quantum Dot Infrared Photodetector (QDIPs) technologies suitable for high pixel-pixel uniformity and high pixel operability large area imaging arrays. In this paper we report the first demonstration of the megapixel-simultaneously-readable and pixel-co-registered dual-band QWIP focal plane array (FPA). In addition, we will present the latest advances in QDIPs and Superlattice infrared detectors at the Jet Propulsion Laboratory.

  8. Key aspects in the modeling of concentrator III-V solar cells and III-V thermophotovoltaic converters

    Microsoft Academic Search

    Carlos Algora

    2004-01-01

    The development of III-V concentrator solar cells and thermophotovoltaic converters is at a critical point in which both sophisticated\\u000a technology and an accurate modeling are required. This paper emphasizes the aspects relating to the modeling of multijunction\\u000a solar cells for the concentration of applications and thermophotovoltaic converters. In the case of solar cells, the key aspects\\u000a are\\u000a \\u000a \\u000a \\u000a – \\u000a \\u000a —Necessity of

  9. 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.

  10. Sulfur passivation techniques for III-V wafer bonding

    NASA Astrophysics Data System (ADS)

    Jackson, Michael James

    The use of direct wafer bonding in a multijunction III-V solar cell structure requires the formation of a low resistance bonded interface with minimal thermal treatment. A wafer bonded interface behaves as two independent surfaces in close proximity, hence a major source of resistance is Fermi level pinning common in III-V surfaces. This study demonstrates the use of sulfur passivation in III-V wafer bonding to reduce the energy barrier at the interface. Two different sulfur passivation processes are addressed. A dry sulfur passivation method that utilizes elemental sulfur vapor activated by ultraviolet light in vacuum is compared with aqueous sulfide and native oxide etch treatments. Through the addition of a sulfur desorption step in vacuum, the UV-S treatment achieves bondable surfaces free of particles contamination or surface roughening. X-ray photoelectron spectroscopy measurements of the sulfur treated GaAs surfaces find lower levels of oxide and the appearance of sulfide species. After 4 hrs of air exposure, the UV-S treated GaAs actually showed an increase in the amount of sulfide bonded to the semiconductor, resulting in less oxidation compared to the aqueous sulfide treatment. Large area bonding is achieved for sulfur treated GaAs / GaAs and InP / InP with bulk fracture strength achieved after annealing at 400 °C and 300 °C respectively, without large compressive forces. The electrical conductivity across a sulfur treated 400 °C bonded n-GaAs/n-GaAs interface significantly increased with a short anneal (1-2 minutes) at elevated temperatures (50--600 °C). Interfaces treated with the NH4OH oxide etch, on the other hand, exhibited only mild improvement in accordance with previously published studies in this area. TEM and STEM images revealed similar interfacial microstructure changes with annealing for both sulfur treated and NH4OH interfaces, whereby some areas have direct semiconductor-semiconductor contact without any interfacial layer. Fitting the observed temperature dependence of zero bias conductance using a model for tunneling through a grain boundary reveals that the addition of sulfur at the interface lowered the interfacial energy barrier by 0.2 eV. The interface resistance for these sulfur-treated structures is less than 0.03 O·cm 2 at room temperature. These results emphasize that sulfur passivation techniques reduce interface states that otherwise limit the implementation of wafer bonding for high efficiency solar cells and other devices.

  11. Design and growth of III–V nanowire solar cell arrays on low cost substrates

    Microsoft Academic Search

    Anjia Gu; Yijie Huo; Shu Hu; T. Sarmiento; Evan Pickett; Dong Liang; Shuang Li; Angie Lin; Shruti Thombare; Zongfu Yu; Shanhui Fan; P. McIntyre; Yi Cui; James Harris

    2010-01-01

    State-of-the-art III-V multijunction cells have achieved a record efficiency of 42.8%, which has fueled great interest in the utility sector for large-scale deployment. However, III-V solar cells have thus far proven too expensive for widespread terrestrial applications due to the combined cost of substrates, growth processes, and materials. Here, we propose a novel III-V solar cell based on the epitaxial

  12. Device physics studies of III-V and silicon MOSFETs for digital logic

    Microsoft Academic Search

    Himadri Sekhar Pal

    2010-01-01

    III-V's are currently gaining a lot of attraction as possible MOSFET channel materials due to their high intrinsic mobility. Several challenges, however, need to be overcome before III-V's can replace silicon (Si) in extremely scaled devices. The effect of low density-of-states of III-V materials is investigated by analyzing the semiconductor capacitance for different device structures and scaling. Solid solubility limit

  13. 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

    2013-06-01

    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. PMID:23736620

  14. 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.

  15. Heterogeneously integrated III-V laser on thin SOI with compact optical vertical interconnect access.

    PubMed

    Pu, Jing; Lim, Kim Peng; Ng, Doris Keh Ting; Krishnamurthy, Vivek; Lee, Chee Wei; Tang, Kun; Seng Kay, Anthony Yew; Loh, Ter Hoe; Wang, Qian

    2015-04-01

    A new heterogeneously integrated III-V/Si laser structure is reported in this report that consists of a III-V ridge waveguide gain section on silicon, III-V/Si optical vertical interconnect accesses (VIAs), and silicon-on-insulator (SOI) nanophotonic waveguide sections. The III-V semiconductor layers are introduced on top of the 300-nm-thick SOI layer through low temperature, plasma-assisted direct wafer-bonding and etched to form a III-V ridge waveguide on silicon as the gain section. The optical VIA is formed by tapering the III-V and the beneath SOI in the same direction with a length of 50 ?m for efficient coupling of light down to the 600 nm wide silicon nanophotonic waveguide or vice versa. Fabrication details and specification characterizations of this heterogeneous III-V/Si Fabry-Perot (FP) laser are given. The fabricated FP laser shows a continuous-wave lasing with a threshold current of 65 mA at room temperature, and the slope efficiency from single facet is 144??mW/A. The maximal single facet emitting power is about 4.5 mW at a current of 100 mA, and the side-mode suppression ratio is ?30??dB. This new heterogeneously integrated III-V/Si laser structure demonstrated enables more complex laser configuration with a sub-system on-chip for various applications. PMID:25831337

  16. 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.

  17. 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.

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

    SciTech Connect

    Chroneos, A., E-mail: alex.chroneos@open.ac.uk [Engineering and Innovation, The Open University, Milton Keynes MK7 6AA (United Kingdom); Tahini, H. A. [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Schwingenschlögl, U., E-mail: udo.schwingenschlogl@kaust.edu.sa [PSE Division, KAUST, Thuwal 23955-6900 (Saudi Arabia); Grimes, R. W., E-mail: r.grimes@imperial.ac.uk [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

    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.

  19. Dopant Profiling of III-V Nanostructures for Electronic Applications

    NASA Astrophysics Data System (ADS)

    Ford, Alexandra Caroline

    2011-12-01

    High electron mobility III-V compound semiconductors such as indium arsenide (InAs) are promising candidates for future active channel materials of electron devices to further enhance device performance. In particular, compound semiconductors heterogeneously integrated on Si substrates have been studied, combining the high mobility of III-V semiconductors and the well-established, low cost processing of Si technology. However, one of the primary challenges of III-V device fabrication is controllable, post-growth dopant profiling. Here InAs nanowires and ultrathin layers (nanoribbons) on SiO2/Si are investigated as the channel material for high performance field-effect transistors (FETs) and post-growth, patterned doping techniques are demonstrated. First, the synthesis of crystalline InAs nanowires with high yield and tunable diameters by using Ni nanoparticles as the catalyst material on SiO 2/Si substrates is demonstrated. The back-gated InAs nanowire FETs have electron field-effect mobilities of ˜4,000 cm2/Vs and ION/IOFF ˜104. The uniformity of the InAs nanowires is demonstrated by large-scale assembly of parallel arrays of nanowires (˜400 nanowires) on SiO2/Si substrates by a contact printing process. This enables high performance, "printable" transistors with 5--10 mA ON currents. Second, an epitaxial transfer method for the integration of ultrathin layers of single-crystalline InAs on SiO2/Si substrates is demonstrated. As a parallel to silicon-on-insulator (SOI) technology, the abbreviation "XOI" is used to represent this compound semiconductor-on-insulator platform. A high quality InAs/dielectric interface is obtained by the use of a thermally grown interfacial InAsOx layer (˜1 nm thick). Top-gated FETs exhibit a peak transconductance of ˜1.6 mS/microm at V DS=0.5V with ION/I OFF >104 and subthreshold swings of 107--150 mV/decade for a channel length of ˜0.5 microm. Next, temperature-dependent I-V and C-V studies of single InAs nanowire FETs are utilized to investigate the intrinsic electron transport properties as a function of nanowire radius. From C-V characterization, the densities of thermally-activated fixed charges and trap states on the surface of as-grown (unpassivated) nanowires are investigated to allow the accurate measurement of the gate oxide capacitance. This allows the direct assessment of the electron field-effect mobility. The field-effect mobility is found to monotonically decrease as the radius is reduced to sub-10 nm, with the low temperature transport data highlighting the impact of surface roughness scattering on the mobility degradation for smaller radius nanowires. Next, the electrical properties of the InAs XOI transistors are studied, showing the critical role of quantum confinement in the transport properties of ultrathin XOI layers. Following the investigation of the electrical properties of undoped InAs nanostructures, post-growth, surface doping processes for InAs nanostructures are addressed. Nanoscale, sulfur doping of InAs planar substrates with high dopant areal dose and uniformity by using a self-limiting monolayer doping approach is demonstrated as a means to create ultrashallow junctions. From transmission electron microscopy (TEM) and secondary ion mass spectrometry (SIMS), a dopant profile abruptness of ˜3.5 nm/decade is observed without significant lattice damage. The n+/ p+ junctions fabricated using this doping method exhibit negative differential resistance (NDR) behavior, demonstrating the utility of this approach for device fabrication with high electrically active sulfur concentrations of ˜8x1018 cm-3. Next, a gas phase doping approach for InAs nanowires and ultrathin XOI layers using zinc is demonstrated as an effective means for enabling post-growth dopant profiling of nanostructures. The versatility of the approach is demonstrated by the fabrication of gated diodes and p-MOSFETs. Electrically active zinc concentrations of ˜1x1019 cm-3 are achieved which is necessary for compensating the high electron concentration at the surface o

  20. Development of X-ray lithography and nanofabrication techniques for III-V optical devices

    E-print Network

    Lim, Michael H. (Michael Hong)

    2002-01-01

    This dissertation covers the development of fabrication techniques for Bragg-grating-based integrated optical devices in III-V materials. Work on this rich family of devices has largely been limited to numerical analysis ...

  1. Thermal considerations for advanced SOI substrates designed for III-V/Si heterointegration

    E-print Network

    Bulsara, Mayank

    Silicon-on-lattice engineered substrates (SOLES) are SOI substrates with embedded Ge layers that facilitate III-V compound integration for advanced integrated circuits. The new materials integration scheme in SOLES requires ...

  2. 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.

  3. Extraction of Virtual-Source Injection Velocity in sub-100 nm III-V HFETs

    E-print Network

    Brar, B.

    We have experimentally extracted the virtual-source electron injection velocity, vx0, of various III-V HFETs at room temperature. This is the carrier velocity that matters for logic applications of these transistors. Sub-100 ...

  4. A ballistic transport model for HEMTs and III-V MOSFETs

    E-print Network

    Warnock, Shireen M

    2013-01-01

    As silicon MOSFETs keep scaling down in size, the continued improvement on their logic performance is threated by their fundamental physical limits. With silicon approaching these limits, MOSFETs designed with III-V ...

  5. Electrochemical Studies of Iii-V Semiconductor Liquid Interfaces.

    NASA Astrophysics Data System (ADS)

    Casagrande, Louis Gregory

    1988-12-01

    Systematic trends in the behavior of stable n -type III-V semiconductor/liquid interfaces have been investigated. The properties of liquid junction solar cells constructed from these materials differed substantially from those of the corresponding metal interfaces. An open-circuit photovoltage of 830 millivolts and an optical-to-electrical conversion efficiency of 11% at simulated 1 Sun, AM1.5 conditions were observed for the n-gallium arsenide/acetonitrile-lithium perchlorate-ferricinium-ferrocene system. This contrasted with photovoltages of 450 millivolts and 5% efficiency typical of n-gallium arsenide/metal interfaces. Plots of the photovoltage as a function of temperature were straight lines with photovoltages extrapolated to be approximately equal to the band gap energy at zero Kelvin. Further kinetic investigations revealed surface-state recombination as the dominant bucking current mechanism in this system. Ex-situ spectroscopic ellipsometry was utilized to elucidate the chemical interactions of the semiconductor/liquid interface and to correlate trends in photovoltage with changes in composition of the surface. It was found that the presence of elemental arsenic can lead to initially increased recombination kinetics, but photoelectrochemical treatment in the acetonitrile-ferrocene system at low photocurrent density modified the surface to yield current-voltage properties similar to those obtained at an arsenic-free interface. These data are used to evaluate several models for the behavior of the corresponding metal junctions. Finally, trends in cell properties with variation in the bulk composition of the semiconductor and the solution were investigated. Negative shifts in equilibrium cell potential with appropriate choice of redox couple led to decreases in photovoltage, although less than predicted for an ideal interface. Increases in band gap energy, by substitution of aluminum for gallium to form aluminum gallium arsenide or substitution of phosphorous for arsenic to form gallium arsenide phosphide, resulted in increased photovoltages at a given redox potential and photocurrent density. The increases in photovoltage were linear with band gap, but were less than the full increase in band gap. Models to explain these discrepancies are discussed. Photovoltage versus temperature plots yielded photovoltages of approximately band gap at zero Kelvin. Trends in photovoltage with equilibrium cell potential paralleled those in gallium arsenide. These indicate dominant chemical interactions for the ternary systems similar to gallium arsenide.

  6. MOVPE Technology for the Growth of III-V Semiconductor Structures

    Microsoft Academic Search

    I. Garcia; B. Galiana; I. Rey-Stolle; C. Algora

    2007-01-01

    Metal-organic vapour phase epitaxy (MOVPE) is the most widely used technology for the growth of III-V compounds in the industry today, and has become the preferred choice for the mass fabrication of a wide range of devices. The I.E.S -U.P.M acquired a research-scale Aixtron MOVPE reactor in 2000 aiming the development of III-V multi-junction concentrator solar cells in a pilot

  7. Reconnaissance des défauts et traitement d’images pour les composés III–V

    Microsoft Academic Search

    Jean-Pierre Fillard

    1987-01-01

    Analyse  Cet article fait le point sur le problème de la détection et de l’analyse du rôle des défauts dans les substrats de matériaux\\u000a III–V en corrélation avec les performances des composants intégrés. La production de composants électroniques ou optoélectroniques\\u000a à partir de matériaux III–V offre des perspectives très favorables d’amélioration des performances de vitesse, puissance dissipée,\\u000a et résistances aux contraintes

  8. Properties of Group-IV, III-V and II-VI Semiconductors

    Microsoft Academic Search

    Sadao Adachi

    2005-01-01

    Almost all the semiconductors of practical interest are the group-IV, III-V and II-VI semiconductors and the range of technical applications of such semiconductors is extremely wide. The purpose of this book is twofold: * to discuss the key properties of the group-IV, III-V and II-VI semiconductors * to systemize these properties from a solid-state physics aspect The majority of the

  9. III–V/Ge channel MOS device technologies in nano CMOS era

    NASA Astrophysics Data System (ADS)

    Takagi, Shinichi; Zhang, Rui; Suh, Junkyo; Kim, Sang-Hyeon; Yokoyama, Masafumi; Nishi, Koichi; Takenaka, Mitsuru

    2015-06-01

    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 advanced LSIs in the future, because of its enhanced carrier transport properties. However, there are many critical issues and difficult challenges for realizing III–V/Ge-based CMOS on the Si platform such as (1) the formation of high-crystal-quality Ge/III–V films on Si substrates, (2) gate stack technologies to realize superior MOS/MIS interface quality, (3) the formation of a source/drain (S/D) with low resistivity and low leakage current, (4) process integration to realize ultrashort channel devices, and (5) total CMOS integration including Si CMOS. In this paper, we review the recent progress in III–V/Ge MOS devices and process technologies as viable approaches to solve the above critical problems on the basis of our recent research activities. The technologies include MOS gate stack formation, high-quality channel formation, low-resistance S/D formation, and CMOS integration. For the Ge device technologies, we focus on the gate stack technology and Ge channel formation on Si. Also, for the III–V MOS device technologies, we mainly address the gate stack technology, III–V channel formation on Si, the metal S/D technology, and implementation of these technologies into short-channel III–V-OI MOSFETs on Si substrates. On the basis of the present status of the achievements, we finally discuss the possibility of various CMOS structures using III–V/Ge channels.

  10. III-V semiconductors on silicon-germanium substrates for multi-junction photovoltaics

    Microsoft Academic Search

    Carrie L. Andre

    2004-01-01

    The epitaxial integration of high quality III-V semiconductors with Si is of fundamental interest for photovoltaic devices since Si substrates offer a lighter, stronger, and cost effective platform for device production. However, the lattice-mismatch between conventional III-V photovoltaic materials and Si generates threading dislocations in the epitaxial device layers, which can limit solar cell performance, depending of the density of

  11. Development of III-V dilute nitride-based solar cells grown by chemical beam epitaxy

    Microsoft Academic Search

    Aristotelis Fotkatzikis

    2007-01-01

    The peculiar properties of III-V dilute nitrides, namely the substantial reduction of the energy bandgap and the increase of the electron effective mass upon the introduction of a small amount of nitrogen in the III-V matrix, make them ideal candidates for solar cell applications. Specifically, the use of 1.0--1.25 eV GaInAsN subcells has been proposed as a potential way of

  12. 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 ?/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 ?/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 ?m) 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 microscopie interférentielle numérique est une nouvelle méthode de mesure qui a une résolution latérale micronique et une résolution verticale nanométrique. Ceci est utile pour l'analyse tri-dimensionnelle des défauts de surface et de la forme des composants dans beaucoup d'applications sur les matériaux massifs et épitaxiés. Dans cet article nous démontrons comment certains défauts peuvent être analysés sur les matériaux et les composants III-V avec deux méthodes interférométriques différentes. La microscopie à saut de phase est mieux adaptée, avec sa résolution de 1 nm et sa meilleure précision, à la mesure des petits défauts de moins de ?/2 en hauteur, ou des surfaces avec des pentes douces et continues, jusqu'à une altitude de 1 ou 2 ?m. Ceci est illustré par les études du polissage de plaquettes d'InP, des défauts sur une couche épitaxiée de GaAs sur InP et des boîtes quantiques sur GaAs. Pour mesurer les motifs, les mésas et les sillons qui ont des marches de plus que ?/2, la microscopie à glissement de franges est le meilleur choix. La résolution verticale est un peu moins bonne que celle de la PSM (4 nm) mais la dynamique verticale est plus grande (15 ?m). Ceci est démontré par les mesures d'un sillon gravé dans une structure laser/détecteur sur une couche quaternaire sur InP et d'un MESFET sur GaAs. En comparaison avec la microscopie électronique et les méthodes de champ proche, la microscopie interférentielle numérique a les avantages de la facilité d'utilisation et de la rapidité. Elle est également capable de résoudre certains problèmes difficiles ou insolubles avec les autres techniques, comme par exemple le profil des sillons étroits, ou la mesure des reliefs enterrés sous une couche transparente. Les inconvénients sont la résolution latérale qui est limitée au pouvoir résolutif de l'objectif et l'introduction d'erreurs liées aux variations des propriétés optiques de l'échantillon qui doivent être prises en compte.

  13. Materials and Device Aspects of III-V 3D Transistors

    NASA Astrophysics Data System (ADS)

    Ye, Peide

    2012-02-01

    Recently, III-V MOSFETs with high drain currents (Ids>1mA/?m) and high transconductances (gm>1mS/?m) have been achieved at sub-micron channel lengths (Lch), thanks to the better understanding and significant improvement in high-k/III-V interfaces. However, to realize a III-V FET at beyond 14nm technology node, one major challenge is how to effectively control the short channel effects (SCE). Due to the higher permittivity and lower bandgap of the channel materials, III-V MOSFETs are more susceptible to SCE than its Si counterpart. The scaling of planar devices stops at around 150nm Lch. The dramatic increase in DIBL beyond 150nm indicates severe impact from 2D electrostatics. Therefore, the introduction of 3-dimensonal (3D) structures to the fabrication of sub-100nm III-V FETs is necessary. In this talk, we will review the materials and device aspects of III-V 3D transistors developed very recently [1-3]. [4pt] [1] Y. Q. Wu et al. IEDM Tech. Dig. 331 (2009).[0pt] [2] M. Radosavljevic et al., IEDM Tech. Dig. 126 (2010).[0pt] [3] J. J. Gu et al. IEDM Tech Dig. 2011 (in press).

  14. Hydrogen incorporation into III-V nitrides during processing

    SciTech Connect

    Pearton, S.J.; Abernathy, C.R.; Vartuli, C.B. [Univ. of Florida, Gainesville, FL (United States)] [and others

    1995-10-01

    Hydrogen is readily incorporated into GaN and related alloys during wet and dry etching, chemical vapor deposition of dielectric overlayers, boiling in water and other process steps, in addition to its effects during MOCVD or MOMBE growth. The hydrogen is bound at defects or impurities and passivates their electrical activity. Reactivation occurs at 450-550{degrees}C, but evolution from the crystal requires much higher temperatures ({ge} 800{degrees}C).

  15. Recent progress in integration of III-V nanowire transistors on Si substrate by selective-area growth

    NASA Astrophysics Data System (ADS)

    Tomioka, Katsuhiro; Fukui, Takashi

    2014-10-01

    We report on the recent progress in electronic applications using III-V nanowires (NWs) on Si substrates using the selective-area growth method. This method could align vertical III-V NWs on Si under specific growth conditions. Detailed studies of the III-V NW/Si heterointerface showed the possibility of achieving coherent growth regardless of misfit dislocations in the III-V/Si heterojunction. The vertical III-V NWs grown using selective-area growth were utilized for high performance vertical field-effect transistors (FETs). Furthermore, III-V NW/Si heterointerfaces with fewer misfit dislocations provided us with a unique band discontinuity with a new functionality that can be used for the application of tunnel diodes and tunnel FETs. These demonstrations could open the door to a new approach for creating low power switches using III-V NWs as building-blocks of future nanometre-scaled electronic circuits on Si platforms.

  16. 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 elemental segregation. In a separate study, compositional instability is observed in lattice-matched InAlN films grown on GaN, for growth beyond a certain thickness. Beyond 200 nm of thickness, two sub-layers with different indium content are observed, the top one with lower indium content.

  17. Development of III-V p-MOSFETs with high-kappa gate stack for future CMOS applications

    NASA Astrophysics Data System (ADS)

    Nagaiah, Padmaja

    As the semiconductor industry approaches the limits of traditional silicon CMOS scaling, non-silicon materials and new device architectures are gradually being introduced to improve Si integrated circuit performance and continue transistor scaling. Recently, the replacement of SiO2 with a high-k material (HfO2) as gate dielectric has essentially removed one of the biggest advantages of Si as channel material. As a result, alternate high mobility materials are being considered to replace Si in the channel to achieve higher drive currents and switching speeds. III-V materials in particular have become of great interest as channel materials, owing to their superior electron transport properties. However, there are several critical challenges that need to be addressed before III-V based CMOS can replace Si CMOS technology. Some of these challenges include development of a high quality, thermally stable gate dielectric/III-V interface, and improvement in III-V p-channel hole mobility to complement the n-channel mobility, low source/drain resistance and integration onto Si substrate. In this thesis, we would be addressing the first two issues i.e. the development high performance III-V p-channels and obtaining high quality III-V/high-k interface. We start with using the device architecture of the already established InGaAs n-channels as a baseline to understand the effect of remote scattering from the high-k oxide and oxide/semiconductor interface on channel transport properties such as electron mobility and channel electron concentration. Temperature dependent Hall electron mobility measurements were performed to separate various scattering induced mobility limiting factors. Dependence of channel mobility on proximity of the channel to the oxide interface, oxide thickness, annealing conditions are discussed. The results from this work will be used in the design of the p-channel MOSFETs. Following this, InxGa1-xAs (x>0.53) is chosen as channel material for developing p-channel MOSFETs. Band engineering, strain induced valence band splitting and quantum confinement is used to improve channel hole mobility. Experimental results on the Hall hole mobility is presented for InxGa1-xAs channels with varying In content, thickness of the quantum well and temperature. Then, high mobility InxGa 1-xAs heterostructure thus obtained are integrated with in-situ deposited high-k gate oxide required for high performance p-MOSFET and discuss the challenges associated with the gated structure and draw conclusions on this material system. Antimonide based channel materials such as GaSb and InxGa 1-xSb are explored for III-V based p-MOSFETs in last two chapters. Options for Sb based strained QW channels to obtain maximum hole mobility by varying the strain, channel and barrier material, thickness of the layers etc. is discussed followed by the growth of these Sb channels on GaAs and InP substrates using molecular beam epitaxy. The physical properties of the structures such as the heterostructure quality, alloy content and surface roughness are examined via TEM, XRD and AFM. Following this, electrical measurement results on Hall hole mobility is presented. The effect of strain, alloy content, temperature and thickness on channel mobility and concentration is reported. Development of GaSb n- and p-MOS capacitor structures with in-situ deposited HfO2 gate oxide dielectric using in-situ deposited amorphous Si (a-Si) interface passivation layer (IPL) to improve the interface quality of high-k oxide and (In)GaSb surface is presented. In-situ deposited gate oxides such as Al2O3 and combination oxide of Al 2O3 and HfO2 with and without the a-Si IPL are also explored as alternate gate dielectrics. Subsequently, MOS capacitor structures using buried InGaSb QWs are demonstrated. Development of an inversion type bulk GaSb with implanted source-drain contacts and in-situ deposited gate oxide HfO2 gate oxide is discussed. The merits of biaxial compressive strain is demonstrated on strained surface and buried channel In0.36 Ga0.64Sb QW MOSFETs with thin top

  18. Electronic Properties and Microhardness of Semiconductor Alloys

    Microsoft Academic Search

    Sylvester Nwabuzor Ekpenuma

    1990-01-01

    The results of theoretical investigations of the properties of semiconductor alloys are presented. First, the effects of alloy disorder on the electronic properties of four III-V quaternary alloys are investigated using an extension of the bonding-antibonding coherent potential approximation (CPA) formalism. The alloys considered have two disordered sublattices so that their chemical formulae have the general form A_{x}B _{1-x}C_ {y}D_{1-y}.

  19. Materials Integration and Metamorphic Substrate Engineering from Silicon to Gallium Arsenide to Indium Phosphide for Advanced III-V/Silicon Photovoltaics

    NASA Astrophysics Data System (ADS)

    Carlin, Andrew M.

    Lattice-mismatched epitaxy in the III-V compound semiconductor system based on III-AsP and related alloys are of enormous importance, and considerable research interest, for many years. The reason is straightforward if one considers the limitations placed on available materials properties for devices dictated by lattice matching to the dominant substrate technologies - Si, GaAs (and/or Ge) and InP. For III-V epitaxy, the lattice constants of these substrates have defined a generation or more of device advances since growth of heterostructures possessing the same equilibrium lattice constants as the substrate yields essentially defect-free (specifically extended defect-free) materials and devices. Removing the restriction of lattice matching to current substrate technology opens a rich spectrum of bandgaps, bandgap combinations, conduction and valence band offsets, etc., that are desirable and exploitable for advancing device technologies for new functionality and greater performance. However successful exploitation of these properties requires mitigation of a variety of extended defects that result from the lattice mismatch between substrate and epitaxial heterostructures. A well known method to achieve this solution is through the use of compositionally (lattice constant-graded) buffer interlayers, in which the equilibrium lattice constants of interlayers are slowly altered by controlled changes in layer composition so that the mismatch strain between the initial substrate and the final device layers is spread across a thickness of buffer. The research accomplished has yielded success for both lattice constant ranges Si - GaAs and GaAs - InP. For the Si - GaAs system, a three step GaP nucleation process on Si has been developed and demonstrated, which maintains total avoidance of creating coalescence-related defects such as antiphase domains and stacking faults resulting from the initial III-V/IV interfaces while reducing overall threading dislocation density by ~10x, to a range of 1×107 cm-2, compared to current state of the art. This reduction can now enable future III-V/Si solar cells based on GaAsP metamorphic buffers in which the underlying Si substrate can participate as an active sub-cell, and such buffers have been demonstrated in this research. Second, in this same lattice constant range, novel GaP/SiGe interfaces on Si were grown and demonstrated to eliminate the small, but not negligible lattice misfit between GaP and Si, and provides a second pathway for future III-V/Si solar cell integration through subsequent metamorphic buffer growth. For the GaAs-InP range of lattice constants, multiple metamorphic buffer strategies, including those based on anion-specific quaternary GaInAsP, combinations of step and linearly-graded buffers, and buffers with multiple ternary alloys were all investigated. Micro-scale phase separation within quaternary anion-graded GaInAsP was identified as a mechanism to significantly inhibit proper lattice misfit strain relaxation, which was explained by thermodynamic arguments consistent with theoretical phase separation. This led to the creation of hybrid step and linearly graded InGaAs/InGaP metamorphic buffers through which phase separation was totally eliminated by avoiding specific compositions that were identified as sources for phase separation. These findings have enabled a realistic path for accessing the full range of bandgaps needed for future high efficiency III-V solar cells through optimized metamorphic III-V grading strategies.

  20. Predicted band structures of III-V semiconductors in the wurtzite phase

    SciTech Connect

    De, A.; Pryor, Craig E. [Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa, Iowa City, Iowa 52242 (United States)

    2010-04-15

    While non-nitride III-V semiconductors typically have a zinc-blende structure, they may also form wurtzite crystals under pressure or when grown as nanowhiskers. This makes electronic structure calculation difficult since the band structures of wurtzite III-V semiconductors are poorly characterized. We have calculated the electronic band structure for nine III-V semiconductors in the wurtzite phase using transferable empirical pseudopotentials including spin-orbit coupling. We find that all the materials have direct gaps. Our results differ significantly from earlier ab initio calculations, and where experimental results are available (InP, InAs, and GaAs) our calculated band gaps are in good agreement. We tabulate energies, effective masses, and linear and cubic Dresselhaus zero-field spin-splitting coefficients for the zone-center states. The large zero-field spin-splitting coefficients we find may facilitate the development of spin-based devices.

  1. Electronic structure of III-V zinc-blende semiconductors from first principles

    NASA Astrophysics Data System (ADS)

    Wang, Yin; Yin, Haitao; Cao, Ronggen; Zahid, Ferdows; Zhu, Yu; Liu, Lei; Wang, Jian; Guo, Hong

    2013-06-01

    For analyzing quantum transport in semiconductor devices, accurate electronic structures are critical for quantitative predictions. Here we report theoretical analysis of electronic structures of all III-V zinc-blende semiconductor compounds. Our calculations are from density functional theory with the semilocal exchange proposed recently [Tran and Blaha, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.102.226401 102, 226401 (2009)], within the linear muffin tin orbital scheme. The calculated band gaps and effective masses are compared to experimental data and good quantitative agreement is obtained. Using the theoretical scheme presented here, quantum transport in nanostructures of III-V compounds can be confidently predicted.

  2. Extremely compact hybrid III-V/SOI lasers: design and fabrication approaches.

    PubMed

    Bondarenko, Olesya; Fang, Cheng-Yi; Vallini, Felipe; Smalley, Joseph S T; Fainman, Yeshaiahu

    2015-02-01

    In this manuscript we discuss state of the art hybrid integration techniques and III-V/Si active components with an emphasis on hybrid distributed feedback (DFB) lasers for telecom applications. We review our work on ultra-compact III-V/Si DFB lasers and further describe design considerations and challenges associated with electrically pumped hybrid lasers. We conclude with a perspective on DFB lasers with extremely small footprint, a direction for future research with potential applications to densely-packed optical interconnects. PMID:25836132

  3. Modeling source-drain tunneling in ultimately scaled III-V transistors

    NASA Astrophysics Data System (ADS)

    Pan, Andrew; Chui, Chi On

    2015-06-01

    Intraband source-drain tunneling is predicted to limit leakage current in sub-10 nm field-effect transistors (FETs). We use non-equilibrium Green's function simulations to study this effect in III-V multigate FETs and derive simple, accurate intraband tunneling formulas suitable for use in compact models or semiclassical device simulators. Band nonparabolicity effects are shown to be quantitatively important and incorporated using band gap scaling. We also supply a general subthreshold electrostatic model including source and drain depletion effects for analytical modeling. Our results enable rapid modeling and simulation of ultimately scaled III-V FETs for device evaluation and optimization.

  4. 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.

  5. 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 (calculated from quantitative x-ray analysis and dislocation density) in each of the buffer layers was within the bounds predicted by existing relaxation models and dependent upon lattice mismatch strain. Lattice-matched In0.49Ga0.51P-GaAs junctions as active regions of a heterojuction bipolar transistor were evaluated by high-resolution transmission electron microscopy and related to device performance. Microscopy was established as a feasible technique for characterizing interfacial roughness which was related to interface crystal quality (quantified by reverse-biased leakage currents) but not low-voltage device performance.

  6. Thermal Considerations for Advanced SOI Substrates Designed for III-V/Si Heterointegration

    E-print Network

    Cedex, France e CEA, LETI, Minatec, F38054 Grenoble France f Raytheon RF Components, 362 Lowell St integrated III-V/Si differential amplifier. SOLES thermal budget The commercially available 100 mm SOLES used integration sequence led to the successful fabrication of InP/Si differential amplifier circuits. Figure 3

  7. III-V\\/Si Device Integration Via Metamorphic SiGe Substrates

    Microsoft Academic Search

    S. A. Ringel; O. Kwon; M. Lueck; J. Boeckl; E. A. Fitzgerald

    2006-01-01

    This paper presents growth, characterization and device results for III-V optoelectronic and solar cell heterostructure devices that have been monolithically integrated on Si via ultra low dislocation density SiGe interlayers. Prior work that has demonstrated high performance single junction solar cells (Andre et al., 2005) and visible wavelength LEDs (Kwon et al., 2005) on Si is extended here to include

  8. Quantum Chemical Study of Arsenic (III, V) Adsorption on Mn-Oxides

    E-print Network

    Sparks, Donald L.

    Quantum Chemical Study of Arsenic (III, V) Adsorption on Mn-Oxides: Implications for Arsenic and reaction energies on both Mn(III) and Mn(IV) sites in an attempt tobetterunderstandAs(III)oxidationbybirnessite,alayeredMn- dioxide mineral. Edge-sharing dioctahedral Mn(III) and Mn(IV) clusters with different combinations

  9. 3D Modeling of Concentrator III-V Multi-Junction Solar Cells

    Microsoft Academic Search

    Mathieu Baudrit; Carlos Algora

    2006-01-01

    Concentration based on III-V solar cells is one of the most promising technologies to reduce cost of PV electricity. To achieve high efficiency making a better use of the solar spectrum and under very high concentration, multijunction solar cells are explored at the IES-UPM. To give a real understanding of all the phenomena occurring inside these devices, the development of

  10. Microplasma breakdown in high-concentration III-V solar cells

    Microsoft Academic Search

    José Ramón González; Ignacio Rey-Stolle; Carlos Algora; Beatriz Galiana

    2005-01-01

    III-V high-concentration solar cells have demonstrated a significant degree of technological maturity. However, before their implantation on an industrial scale, these devices need to go through many tests in order to prove their reliability. While carrying out these tests in reverse bias, microplasma breakdown was found in these devices. Therefore, this letter presents the microplasma breakdown, never reported before, for

  11. High temperature thermoelectric characterization of III-V semiconductor thin films by oxide bonding

    E-print Network

    Bowers, John

    material characterization of semiconductor thin films for thermoelectric power generation, photovoltaicAs:InGa(Al)As materials have been used to build thermoelectric power generator modules to generate output power densityPage 1 High temperature thermoelectric characterization of III-V semiconductor thin films by oxide

  12. Flicker Noise Characterization and Modeling of Homo and Hetero-Junction III-V Tunnel FETs

    E-print Network

    Yener, Aylin

    Flicker Noise Characterization and Modeling of Homo and Hetero-Junction III-V Tunnel FETs R hetero-junction Tunnel Field Effect Transistors were demonstrated with MOSFET-like high drive currents due to reduction in the effective tunneling barrier (Ebeff) at the hetero- interface. In this work, we

  13. Hybridization of III-V semiconductor membranes onto ion-exchanged waveguides

    Microsoft Academic Search

    Matthieu Nannini; Etienne Grondin; Arnaud Gorin; Vincent Aimez; Jean-Emmanuel Broquin

    2005-01-01

    In this paper, we present an original method for the realization of hybrid photonic integrated circuits (PICs) based on ion-exchanged (IE) waveguides and III-V semiconductor materials. In our approach, we propose to bond thin semiconductor membranes at designated locations of the PIC where active functions are required. The advantage of very thin membranes is the possibility to keep the optical

  14. Ballistic recovery in III-V nanowire transistors M. J. Gilberta

    E-print Network

    Gilbert, Matthew

    Ballistic recovery in III-V nanowire transistors M. J. Gilberta and S. K. Banerjee Microelectronics of polar optical phonon processes allow devices to recover their ballistic behavior even in the presence different simulations of ballistic operation of these devices.2,3 However, recent work has shown

  15. European PVSECE Glasgow, Scotland 2000 III-V SPACE SOLAR CELLS ON Si SUBSTRATES USING GRADED GeSi BUFFERS

    E-print Network

    16th European PVSECE ­ Glasgow, Scotland 2000 III-V SPACE SOLAR CELLS ON Si SUBSTRATES USING GRADED Cells - 3 1. INTRODUCTION III-V solar cells for space applications are currently grown on Ge wafers due, OH USA ABSTRACT: Single junction AlGaAs/GaAs and InGaP/GaAs solar cells and test structures have been

  16. Experimental demonstration of a hybrid III-V-on-silicon microlaser based on resonant grating cavity mirrors.

    PubMed

    de Koninck, Yannick; Raineri, Fabrice; Bazin, Alexandre; Raj, Rama; Roelkens, Gunther; Baets, Roel

    2013-07-15

    We present the experimental demonstration of a novel class of hybrid III-V-on-silicon microlasers. We show that by coupling a silicon cavity to a III-V waveguide, the interaction between the propagating mode in the III-V waveguide and the cavity mode in the silicon resonator results in high, narrowband reflection back into the III-V waveguide, forming a so-called resonant mirror. By combining two such mirrors and providing optical gain in the III-V wire between these two mirrors, laser operation can be realized. This optically pumped device measures 55 by 2 ?m, requires microwatt-level threshold pump power, and shows single-mode laser emission with a side-mode suppression ratio of up to 39 dB. PMID:23939092

  17. 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)

    1990-01-01

    The III-V films are grown on large automatically perfect terraces of III-V substrates which have a different lattice constant, with temperature and Group III and V arrival rates chosen to give a Group III element stable surface. The growth is pulsed to inhibit Group III metal accumulation of 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 monolayers 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) through (3).

  18. High dielectric constant oxides on III-V complementary metal-oxide-semiconductors

    NASA Astrophysics Data System (ADS)

    Chobpattana, Varistha

    Suitable gate dielectrics are needed for III-V channel metal-oxide-semiconductor field-effect transistors (MOSFETs). III-V semiconductor surfaces tend to have high interface trap state density (Dit). High quality gate dielectrics require a high dielectric constant, a stable interface, and low Dit. The major challenges are scaling down the dielectric to achieve high capacitance densities, understanding defects at the oxide/semiconductor interface, and developing techniques to passivate Dit at the interface. By using nitrogen plasma pre-treatment passivation technique, MOSCAPs with ALD HfO 2 directly on InGaAs as high-k gate stack, with accumulation capacitance density 2.4 mu F/cm2 (EOT=0.6 nm) and 2.5 x 10 12 cm2 eV-1 midgap Dit have been achieved.

  19. 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).

  20. Hybrid III-V/silicon single-mode laser with periodic microstructures.

    PubMed

    Zhang, Yejin; Qu, Hongwei; Wang, Hailing; Zhang, Siriguleng; Ma, Shaodong; Qi, Aiyi; Feng, Zhigang; Peng, Hongling; Zheng, Wanhua

    2013-03-15

    In this Letter, a III-V/silicon hybrid single-mode laser operating at C band for photonic integration circuit is presented. The InGaAlAs gain structure is bonded onto a patterned silicon-on insulator through wafer to wafer directly. The mode selected mechanism based on a hybrid III-V/silicon straight cavity with periodic microstructures is applied, which only need low cost i-line projection photolithography in the whole technological process. At room temperature, we obtain 0.62 mW output power in continuous-wave. The side mode suppression ratio of larger than 20 dB is obtained from experiments. [corrected]. PMID:23503234

  1. 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.

  2. III-V silicon heterogeneous integration for integrated transmitters and receivers

    NASA Astrophysics Data System (ADS)

    Van Thourhout, D.; Van Campenhout, J.; Roelkens, G.; Brouckaert, J.; Baets, R.

    2008-02-01

    Silicon is excellent material for realizing compact nanophotonic ICs operating at wavelengths in the telecom range. Moreover, the desired circuits can be realized with the most advanced equipment available, used also for the fabrication of high-end electronic circuits. Efficient light emission and amplification directly from silicon remains a bottleneck however. Therefore, we developed an alternative approach, based on the heterogeneous integration of III-V epitaxial material and silicon nanophotonic circuits. Following fabrication and planarization of the latter, small unprocessed dies of InP-based epitaxial material are bonded on top. Next, the substrate of these dies is removed down to an etch stop layer. Finally the desired active optoelectronic devices are processed in the remaining III-V layers using waferscale processes. The critical alignment between the sources and the underlying nanophotonic circuits is ensured through accurate lithography. In this paper we review some recent devices fabricated through this integration process.

  3. III-V-semiconductor-based surface-micromachined catilevers for micro-opto-mechanical systems

    NASA Astrophysics Data System (ADS)

    Mao, Jin; Tong, Hua; Zhou, Dan; Jia, Zhensheng; Wang, Jianhua; Xie, Shizhong

    2001-10-01

    Surface micromachining processes based on III-V compound semiconductors are presented in this paper, in order to develop Micro-Opto-Electro-Mechanical systems (MOEMS). By fabricating micro cantilevers composed of seven InP/Air gap pairs, the major techniques of the surface micromachining are studied, including non-selective and selective etching, rinsing and drying. A severe problem of the sticking phenomena during rinsing and drying is avoided by the implementation of the Critical Point Drying (CPD) method.

  4. Device physics studies of III-V and silicon MOSFETs for digital logic

    NASA Astrophysics Data System (ADS)

    Pal, Himadri Sekhar

    III-V's are currently gaining a lot of attraction as possible MOSFET channel materials due to their high intrinsic mobility. Several challenges, however, need to be overcome before III-V's can replace silicon (Si) in extremely scaled devices. The effect of low density-of-states of III-V materials is investigated by analyzing the semiconductor capacitance for different device structures and scaling. Solid solubility limit of dopants in the III-V materials are also significantly lower than that in Si, causing high series resistance, and transconductance degradation due to source exhaustion. The metallic source/drain Schottky barrier MOSFET is explored as an alternative to effectively eliminate these issues. The performance of a Si channel SOI MOSFET fabricated at IBM is analyzed and interpreted using ballistic transport. The ballistic ratio and extracted mean free paths demonstrate that scattering effects cannot be ignored in modern Si channel devices. Scattering has been implemented within the non-equilibrium Green's function (NEGF) framework to investigate effects of phonon and surface roughness scattering on device performance. The computational complexity is greatly reduced by analytically integrating over the transverse (width) dimension, making it possible to include scattering in planar FETs. The model has been carefully benchmarked with analytical formulas and Boltzmann transport calculations (2-D Monte Carlo results) for simple potential profiles. The scattering model is used to study the role of phonon scattering on the on-state characteristics of Si channel devices. Finally, the role of surface roughness scattering and its implementation issues within NEGF is discussed.

  5. Blocking of indium incorporation by antimony in III-V-Sb nanostructures

    NASA Astrophysics Data System (ADS)

    Sanchez, A. M.; Beltran, A. M.; Beanland, R.; Ben, T.; Gass, M. H.; de la Peña, F.; Walls, M.; Taboada, A. G.; Ripalda, J. M.; Molina, S. I.

    2010-04-01

    The addition of antimony to III-V nanostructures is expected to give greater freedom in bandgap engineering for device applications. One of the main challenges to overcome is the effect of indium and antimony surface segregation. Using several very high resolution analysis techniques we clearly demonstrate blocking of indium incorporation by antimony. Furthermore, indium incorporation resumes when the antimony concentration drops below a critical level. This leads to major differences between nominal and actual structures.

  6. The last development in III-V multi-junction solar cells

    Microsoft Academic Search

    Q. A. H. Al Naser; H. W. Hilou; A. F. Abdulkader

    2009-01-01

    Multi-junction solar cells fabricated from III-V semiconductor materials exhibit high efficiencies matched by no other existing photovoltaic technology. Multi-junction solar cells are composed of 3 layers of material that have different band gaps. The top layer has the largest band gap while the bottom layer has the smallest band gap. This design allows less energetic photons to pass through the

  7. Characterization of monolithic III–V multi-junction solar cells—challenges and application

    Microsoft Academic Search

    M. Meusel; C. Baur; G. Siefer; F. Dimroth; A. W. Bett; W. Warta

    2006-01-01

    The characterization of monolithic III–V multi-junction solar cells is still a challenging task. In this paper we show that quantum efficiency measurements have to be performed under optimized light- and voltage-bias conditions to minimize measurement artifacts. They appear, if the subcell to be measured has a low shunt resistance or a low reverse breakdown voltage. Moreover, cells with increasing number

  8. Development of III-V-based concentrator solar cells and their application in PV-modules

    Microsoft Academic Search

    A. W. Bett; F. Dimroth; M. Hein; G. Lange; M. Meusel; U. Schubert; G. Siefer

    2002-01-01

    Concentrators have a great potential to achieve cost reduction for solar generated electricity. In this work III-V-based concentrator solar cells for high concentration levels were fabricated. Monolithic and mechanically stacked multi-junction cells were investigated achieving efficiencies up to 33.5 % at C=308 (AM1.5d, 1000W\\/m2, 25°C). The cells are employed in point-focus Fresnel lens modules. All-glass hermetized modules designed for a

  9. III–V compound multi-junction solar cells: present and future

    Microsoft Academic Search

    Masafumi Yamaguchi

    2003-01-01

    As a result of top cell material quality improvement, development of optically and electrically low-loss double-hetero structure tunnel junction, photon and carrier confinements, and lattice-matching between active cell layers and substrate, the last 15 years have seen large improvements in III–V compound multi-junction (MJ) solar cells. In this paper, present status of R&D program for super-high-efficiency MJ cells in the

  10. Magnetotransport properties of p-type (In,Mn)As diluted magnetic III-V semiconductors

    Microsoft Academic Search

    H. Ohno; H. Munekata; T. Penney; S. von Molnár; L. L. Chang

    1992-01-01

    Magnetotransport properties of p-type (In,Mn)As, a new diluted magnetic semiconductor based on a III-V semiconductor, are studied. The interaction between the holes and the Mn 3d spins is manifested in the anomalous Hall effect, which dominates the Hall resistivity from low temperature (0.4 K) to nearly room temperature, and in the formation of partial ferromagnetic order below 7.5 K, which

  11. Low-temperature photo-hydro-modification of II–VI and III–V semiconductors

    Microsoft Academic Search

    A. M. Kamuz; P. F. Oleksenko; E. Yu. Ovsyannikov; F. F. Sizov; T. A. Dyachenko

    1996-01-01

    The purpose of this paper was the investigation of a photostimulated modification of optical properties of semiconductors subsurface region, to create elements and devices of integrated optics. The experiments have been carried out in II–VI (CdS, CdTe) and III–V (GaAs) semiconductor single crystals. It was shown that during the photostimulated process the enriching of cadmium occurs in the subsurface region

  12. Interpreting interfacial structure in cross-sectional STM images of III–V semiconductor heterostructures

    Microsoft Academic Search

    B. Z. Nosho; W. Barvosa-Carter; M. J. Yang; B. R. Bennett; L. J. Whitman

    2000-01-01

    Using model GaSb–InAs heterostructures, we have systematically examined how cross-sectional scanning tunneling microscopy (XSTM) can be used for the study of III–V heterostructure interfaces. The interpretation of interfacial structure in XSTM images is impeded by the fact that only every other III or V plane as grown on the (001) substrate is seen in each image. We show how this

  13. Growth and characterization of thin film III-V compound semiconductor material for solar cell applications

    Microsoft Academic Search

    W. D. Johnston Jr.

    1979-01-01

    The paper presents an overview of the growth and characterization of thin film III-V compound semiconductor materials for solar cell applications. Attention is given to the cost analysis of GaAs or InP solar cells prepared on single crystal substrates, and to the basic properties of polycrystalline thin films. Growth techniques of GaAs solar cells are discussed, including reversible reactions, the

  14. New and unified model for Schottky barrier and III--V insulator interface states formation

    Microsoft Academic Search

    W. E. Spicer; P. W. Chye; P. R. Skeath; C. Y. Su; I. Lindau

    1979-01-01

    For n- and p-doped III--V compounds, Fermi-level pinning and accompanying phenomena of the (110) cleavage surface have been studied using photoemission at h..nu..< or approx. =300 eV (so that core as well as valence band levels could be studied). Both the clean surfaces and the changes produced, as metals or oxygen are added to those surfaces in submonolayer quantities, have

  15. Time dependent simulations of the growth of III–V crystals by the liquid phase electroepitaxy

    Microsoft Academic Search

    Zbigniew R. Zytkiewicz; Pawel Strak; Stanislaw Krukowski

    2011-01-01

    Results of time dependent simulations of growth of bulk binary III–V crystals by current controlled liquid phase electroepitaxy (LPEE) are reported using GaAs as an example. Without any electrical current the LPEE system is isothermal, kept at 1073K, thus no growth occurs. The electric current density of 10A\\/cm2 leads to ohmic heating of the entire system, Peltier cooling of the

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

    DOEpatents

    Alivisatos, A. Paul (Oakland, CA); Peng, Xiaogang (Fayetteville, AR); Manna, Liberato (Palo del Colle, IT)

    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.

  17. Static and dynamical properties of II–VI and III–V group binary solids

    Microsoft Academic Search

    D S Yadav; D V Singh

    2012-01-01

    In this paper, we extend to II–VI and III–V group binary solids of zinc blende (ZB) structure with conduction d-electrons the calculation of static and dynamical properties such as bulk modulus (B) and cohesive energy or total energy (Ecoh) using the plasma oscillation theory of solids formalism already employed for ternary chalcopyrite semiconductors. The present method is not limited to

  18. Atomic strings of group IV, III-V, and II-VI elements

    Microsoft Academic Search

    S. Tongay; E. Durgun; S. Ciraci

    2004-01-01

    A systematic first-principles study of atomic strings made by group IV, III-V, and II-VI elements has revealed interesting mechanical, electronic, and transport properties. The double bond structure underlies their unusual properties. We found that linear chain of C, Si, Ge, SiGe, GaAs, InSb, and CdTe are stable and good conductor, although their parent diamond (zincblende) crystals are covalent (polar) semiconductors

  19. Structural studies of III–V and group IV semiconductors at high pressure

    Microsoft Academic Search

    R. J. Nelmes; M. I. McMahon; N. G. Wright; D. R. Allan; H. Liu; J. S. Loveday

    1995-01-01

    Extensive new structural results on II–VI, III–V and group IV semiconductors under pressure have been obtained over the past two years at SRS Daresbury, using angle-dispersive techniques and an image-plate detector. In this paper, a brief overview is presented of recent work on Si, Ge, GaSb, InSb, InAs, InP and GaAs.

  20. Electrical and optical characterization of Group III-V heterostructures with emphasis on terahertz devices

    Microsoft Academic Search

    Aruna B. Weerasekara

    2007-01-01

    Electrical and optical characterizations of heterostructures and thin films based on group III-V compound semiconductors are presented. Optical properties of GaMnN thin films grown by Metalorganic Chemical Vapor Deposition (MOCVD) on GaN\\/Sapphire templates were investigated using IR reflection spectroscopy. Experimental reflection spectra were fitted using a non-linear fitting algorithm, and the high frequency dielectric constant (epsiloninfinity), optical phonon frequencies of

  1. Bifunctional redox flow battery-1 V(III)\\/V(II)–glyoxal(O 2) system

    Microsoft Academic Search

    Y. H. Wen; J. Cheng; P. H. Ma; Y. S. Yang

    2008-01-01

    Bifunctional redox flow batteries (BRFB) possess functions of both electricity storage and electrochemical preparation, having the potential for increasing the electrical energy utilization. A V(III)\\/V(II)–glyoxal(O2) system has been developed. Separators of the BRFB play a key role in BRFB performance. A Nafion solution was sprayed on a gas diffusion layer (GDL) at the Nafion loading of 2mgcm?2, and the GDL

  2. 40 Gbit\\/s transmission: III-V integrated circuits for opto-electronic interfaces

    Microsoft Academic Search

    André Scavennec; Jean Godin; René Lefevre

    2003-01-01

    Increasing both wavelength count and bit rate per channel is presently implemented in order to improve the use of optical\\u000a fiber bandwidth. This calls for suitable device structures and technologies for both optoelectronic transducers and associated\\u000a driving electronics. For transmission at 40 Gbit\\/s per channel, Si and III–V microelectronic technologies are presently investigated\\u000a with first successful demonstrations. In this paper

  3. ccsd00003231, Long-range ordering of III-V semiconductor

    E-print Network

    ccsd­00003231, version 1 ­ 29 Nov 2004 Long-range ordering of III-V semiconductor nanostructures from a GaAs/InAs/InGaAs/GaAs sequence grown on GaAs by metalorganic vapour phase epitaxy at two di#11) that forms, between a thin GaAs layer (on which growth was performed) and a GaAs substrate joined together

  4. The III-V semiconductor quantum well lasers and related optoelectronic devices on silicon

    Microsoft Academic Search

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

    1989-01-01

    The research goal is to further develop quantum well heterostructure (QWH) lasers and to realize reliable Al(x)Ga(1-x)As-GaAs QWH lasers on Si. In spite of the significant lattice and thermal expansion mismatch between GaAs and Si, the idea of splicing III-V semiconductor technology, i.e., optoelectronics and photonics, onto Si has obvious appeal. Adding to this is the fact, as shown earlier

  5. Heterogeneous Integration of III-V Active Devices on a Silicon-on-Insulator Photonic Platform

    Microsoft Academic Search

    G. Roelkens; J. Brouckaert; J. Van Campenhout; D. Van Thourhout; R. Baets

    2007-01-01

    We present the heterogeneous integration of III-V active opto-electronic devices on top of a silicon-on-insulator photonic integrated circuit. This is achieved by adhesive die-to-wafer bonding of an unprocessed InP\\/InGaAsP epitaxial layer structure, after which laser diodes and photodetectors were fabricated in the bonded layer and optically coupled to the underlying silicon-on-insulator waveguide circuit.

  6. R&D on III-V Compound Solar Cells for Space Application at TIPS

    Microsoft Academic Search

    Wenjun Chen; Fusheng Du; Qiang Sun; Zhibin Xiao; Zaixiang Qiao; Jun Xu; Yanzheng Sun; Shouyan Xu

    2006-01-01

    Driven by the market needs from high capacity telecommunication satellites, Tianjin Institute of Power Sources has made intensive efforts to develop GaAs based III-V compound solar cells in the last decade. A 20 KW\\/year production line was soon established and solar panels with GaAs\\/Ge single junction solar cells of excellent performance have been delivered for several telecommunication satellite projects. Meanwhile,

  7. Progress of inverted metamorphic III–V solar cell development at Spectrolab

    Microsoft Academic Search

    Hojun Yoon; Moran Haddad; Shoghig Mesropian; Jason Yen; Kenneth Edmondson; Daniel Law; Richard R. King; Dhananjay Bhusari; Andreea Boca; Nasser H. Karam

    2008-01-01

    Inverted metamorphic (IMM) solar cells based on III–V materials have the potential to achieve solar conversion efficiencies that are significantly higher than today's state of the art solar cells which are based on the 3-junction GaInP\\/GaInAs\\/Ge design. The 3J IMM device architecture based on (Al)GaInP\\/GaInAs\\/GaInAs, for example, allows for a higher voltage solar cell by replacing the low bandgap Ge

  8. Theoretical prediction of topological insulators in thallium-based III-V-VI2 ternary chalcogenides

    Microsoft Academic Search

    Binghai Yan; Chao-Xing Liu; Hai-Jun Zhang; Chi-Yung Yam; Xiao-Liang Qi; Thomas Frauenheim; Shou-Cheng Zhang

    2010-01-01

    We predict a new class of three-dimensional topological insulators in thallium-based III-V-VI2 ternary chalcogenides, including TlBiQ2 and TlSbQ2 (Q=Te, Se and S). These topological insulators have robust and simple surface states consisting of a single Dirac cone at the Gamma point. The mechanism for topological insulating behavior is elucidated using both first-principle calculations and effective field theory models. Remarkably, one

  9. Chapter 7.42 Oxford Plasmalab 100 ICP (Compound III-V)

    E-print Network

    Healy, Kevin Edward

    .1 Oxford-icp is an ICP-Bias plasma etcher built to etch InP, GaAs, and other 3-5 materials. At this time delicate balance of multiple etch, passivation, and sputter mechanisms. Sidewalls with rough and #12;oxford-icpChapter 7.42 Oxford Plasmalab 100 ICP (Compound III-V) (oxford-icp) (584) 1.0 Equipment Purpose 1

  10. Performance and Reliability of Multijunction III-V Modules for Concentrator Dish and Central Receiver Applications

    Microsoft Academic Search

    Pierre J. Verlinden; Allan Lewandowski; Carl Bingham; Geoffrey S. Kinsey; Raed A. Sherif; John B. Lasich

    2006-01-01

    Over the last 15 years, Solar Systems have developed a dense array receiver PV technology for 500X concentrator reflective dish applications. This concentrator PV technology has been successfully deployed at six different locations in Australia, counting for more than 1 MWp of installed peak power. A new Multijunction III-V receiver to replace the current silicon Point-Contact solar cells has recently

  11. III-V solar cell growth on wafer-bonded GaAs\\/Si-substrates

    Microsoft Academic Search

    J. Schone; F. Dimroth; A. W. Bett; A. Tauzin; C. Jaussaud; J.-C. Roussin

    2006-01-01

    The MOVPE (Metal Organic Vapour Phase Epitaxy) growth of GaAs single-junction solar cells on layer transferred GaAs\\/Si-substrates is reported. This novel type of alternative substrates for III-V epitaxial growth was realised by performing the Smart Cuttrade technology. HRXRD-measurements proved good material quality by a FWHM of about 30 arcsecond reveal a dislocation density below 4times105 cm -2 for a 5

  12. Surface influence on stability and structure of hexagon-shaped III-V semiconductor nanorods

    Microsoft Academic Search

    R. Leitsmann; F. Bechstedt

    2007-01-01

    We report ab initio investigations of hexagon-shaped, [111]\\/[0001]-oriented III-V semiconductor nanowires with varying crystal structure, surface passivation, surface orientation, and diameter. Their stability is dominated by the free surface energies of the corresponding facets, which differ only weakly from those of free surfaces. We observe a phase transition between local zinc-blende and wurtzite geometry versus preparation conditions of the surfaces,

  13. Band gap bowings and anomalous pressure effects in IIIV nitride alloys

    E-print Network

    Svane, Axel Torstein

    N, InxAl1ÀxN and GaxAl1ÀxN is performed to examine the role of indium in nitride alloys. The band gap, EgBand gap bowings and anomalous pressure effects in III­V nitride alloys: Role of In-segregation I Keywords gap bowings, nitride alloys, pressure coefficients * Corresponding author: e-mail iza

  14. Phase Separation and Atomic Ordering in Epitaxial Semiconductor Alloys Studied by Transmission Electron Microscopy

    Microsoft Academic Search

    Scott Phillip Ahrenkiel

    1995-01-01

    Transmission electron microscopy (TEM) is used to examine the microstructure of epitaxial II-VI and III -V ternary semiconductor alloys. Emphasis is placed on the crystallographic aspects of alloy ordering and phase separation and the influence of growth parameters. Quantitative methods of image and diffraction pattern analysis are examined. TEM studies of novel II-VI pseudobinary alloys grown by molecular beam epitaxy

  15. Growth and optical properties of axial hybrid III-V/silicon nanowires

    NASA Astrophysics Data System (ADS)

    Hocevar, Moïra; Immink, George; Verheijen, Marcel; Akopian, Nika; Zwiller, Val; Kouwenhoven, Leo; Bakkers, Erik

    2012-12-01

    Hybrid silicon nanowires with an integrated light-emitting segment can significantly advance nanoelectronics and nanophotonics. They would combine transport and optical characteristics in a nanoscale device, which can operate in the fundamental single-electron and single-photon regime. III-V materials, such as direct bandgap gallium arsenide, are excellent candidates for such optical segments. However, interfacing them with silicon during crystal growth is a major challenge, because of the lattice mismatch, different expansion coefficients and the formation of antiphase boundaries. Here we demonstrate a silicon nanowire with an integrated gallium-arsenide segment. We precisely control the catalyst composition and surface chemistry to obtain dislocation-free interfaces. The integration of gallium arsenide of high optical quality with silicon is enabled by short gallium phosphide buffers. We anticipate that such hybrid silicon/III-V nanowires open practical routes for quantum information devices, where for instance electronic and photonic quantum bits are manipulated in a III-V segment and stored in a silicon section.

  16. Growth and optical properties of axial hybrid III-V/silicon nanowires.

    PubMed

    Hocevar, Moïra; Immink, George; Verheijen, Marcel; Akopian, Nika; Zwiller, Val; Kouwenhoven, Leo; Bakkers, Erik

    2012-01-01

    Hybrid silicon nanowires with an integrated light-emitting segment can significantly advance nanoelectronics and nanophotonics. They would combine transport and optical characteristics in a nanoscale device, which can operate in the fundamental single-electron and single-photon regime. III-V materials, such as direct bandgap gallium arsenide, are excellent candidates for such optical segments. However, interfacing them with silicon during crystal growth is a major challenge, because of the lattice mismatch, different expansion coefficients and the formation of antiphase boundaries. Here we demonstrate a silicon nanowire with an integrated gallium-arsenide segment. We precisely control the catalyst composition and surface chemistry to obtain dislocation-free interfaces. The integration of gallium arsenide of high optical quality with silicon is enabled by short gallium phosphide buffers. We anticipate that such hybrid silicon/III-V nanowires open practical routes for quantum information devices, where for instance electronic and photonic quantum bits are manipulated in a III-V segment and stored in a silicon section. PMID:23232396

  17. 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. PMID:23393621

  18. Theoretical consideration of III-V nanowire/Si triple-junction solar cells.

    PubMed

    Wen, Long; Li, Xinhua; Zhao, Zhifei; Bu, Shaojiang; Zeng, XueSong; Huang, Jin-hua; Wang, Yuqi

    2012-12-21

    In this paper, we report theoretical consideration and simulation of a proposed III-V nanowire (NW)/Si triple-junction solar cell. The cell consists of two axially connected III-V NW subcells that are grown and electrically integrated on an active Si substrate. The optical properties of the cell are thoroughly analyzed by using the finite-difference time-domain method. It is found that NW subcells with optimized geometry have high absorption throughout their absorption region. Meanwhile, beyond the absorption edge of the top and middle NW subcells, the NWs act as an efficient antireflection coating for the bottom Si subcell due to the formation of an optical cavity within the NW layer. The physics responsible for the enhanced light harvesting process is qualitatively explained through modal analysis. In addition, we have shown that the condition of current matching in a III-V NW/Si multi-junction can be fulfilled by adjusting the diameter of the NWs. In order to study the current-voltage characteristics of the proposed cell, the optical generation profiles under AM1.5G illumination are incorporated into an electrical modeling. Our optoelectrical simulations indicate that, with an excellent current matching between subcells, the performance of the proposed structure is comparable with state-of-the-art multi-junction cells. The results presented here indicate that semiconductor NWs may provide a promising route toward high efficiency multi-junction solar cells. PMID:23182996

  19. Theoretical consideration of III-V nanowire/Si triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Wen, Long; Li, Xinhua; Zhao, Zhifei; Bu, Shaojiang; Zeng, XueSong; Huang, Jin-hua; Wang, Yuqi

    2012-12-01

    In this paper, we report theoretical consideration and simulation of a proposed III-V nanowire (NW)/Si triple-junction solar cell. The cell consists of two axially connected III-V NW subcells that are grown and electrically integrated on an active Si substrate. The optical properties of the cell are thoroughly analyzed by using the finite-difference time-domain method. It is found that NW subcells with optimized geometry have high absorption throughout their absorption region. Meanwhile, beyond the absorption edge of the top and middle NW subcells, the NWs act as an efficient antireflection coating for the bottom Si subcell due to the formation of an optical cavity within the NW layer. The physics responsible for the enhanced light harvesting process is qualitatively explained through modal analysis. In addition, we have shown that the condition of current matching in a III-V NW/Si multi-junction can be fulfilled by adjusting the diameter of the NWs. In order to study the current-voltage characteristics of the proposed cell, the optical generation profiles under AM1.5G illumination are incorporated into an electrical modeling. Our optoelectrical simulations indicate that, with an excellent current matching between subcells, the performance of the proposed structure is comparable with state-of-the-art multi-junction cells. The results presented here indicate that semiconductor NWs may provide a promising route toward high efficiency multi-junction solar cells.

  20. Broadband and omnidirectional anti-reflection layer for III/V multi-junction solar cells

    E-print Network

    Diedenhofen, Silke L; Haverkamp, Erik; Bauhuis, Gerard; Schermer, John; Rivas, Jaime Gómez; 10.1016/j.solmat.2012.02.022

    2012-01-01

    We report a novel graded refractive index antireflection coating for III/V quadruple solar cells based on bottom-up grown tapered GaP nanowires. We have calculated the photocurrent density of an InGaP-GaAs-InGaAsP-InGaAs solar cell with a MgF2/ZnS double layer antireflection coating and with a graded refractive index coating. The photocurrent density can be increased by 5.9 % when the solar cell is coated with a graded refractive index layer with a thickness of 1\\mu m. We propose to realize such a graded refractive index layer by growing tapered GaP nanowires on III/V solar cells. For a first demonstration of the feasibility of the growth of tapered nanowires on III/V solar cells, we have grown tapered GaP nanowires on AlInP/GaAs substrates. We show experimentally that the reflection from the nanowire coated substrate is reduced and that the transmission into the substrate is increased for a broad spectral and angular range.

  1. 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 so improve their roughness and degree of relaxation. This effect, combined with a threading dislocation filtering structure, is anticipated to produce high quality buffers for lattice-mismatched film growth.

  2. Magnetic and magnetotransport investigations of manganese doped ferromagnetic II-VI and III-V diluted magnetic semiconductors (DMS)

    Microsoft Academic Search

    Mustafa Eginligil

    2010-01-01

    This dissertation describes efforts to study and understand magnetic and electrical transport properties of diluted magnetic semiconductors (DMS), particularly the role of manganese (Mn) in II-VI and III-V DMS. It is divided into two chapters; both focused on ferromagnetism, collective alignment of spins, and in the III-V system how this affects transport properties; understanding is vital for semiconductor spintronics applications.

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

    NASA Astrophysics Data System (ADS)

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

    2002-10-01

    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.

  4. 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.

  5. Ultraviolet photodetectors and imaging arrays based on III-V nitride heterostructures

    NASA Astrophysics Data System (ADS)

    Brown, Jeffrey David

    2000-10-01

    The III-V nitride class of compound semiconductors has received much attention in the last decade. These materials have a wide, direct bandgap, making them a prime candidate for optoelectronic devices in the blue, green, and ultraviolet spectral regions. These materials exhibit impressive optical, electrical, and thermal properties, even though there are fundamental materials issues that are thus far unresolved. This work explores the application of III-V nitride semiconductors to optical detectors in the ultraviolet region of the electromagnetic spectrum. Metalorganic vapor phase epitaxy was used to synthesize thin film p-i-n photodiode structures on double side polished sapphire substrates; these films were characterized for optical, electrical and structural properties. The grown structures were designed to respond to a predetermined region of the UV spectrum when illuminated from the substrate side. These structures were fabricated into devices using generally accepted techniques for dry etching and p and n-contact metallizations. Test devices were characterized using tools developed by the author. These devices demonstrated as high as 80% quantum efficiency and extremely low dark currents; resulting in spectral detectivities as large as 6 * 1013 cmHz1/2W-1. Devices were designed and demonstrated for a series of detection regions ranging from 365 nm to 250 nm. Photolithography masks were designed to allow the fabrication of photodiode arrays that would hybridize to commercially available CMOS based readout integrated circuits (ROICs), used routinely for infrared photodiode imaging. Photodiode arrays were fabricated and indium bumps were deposited onto the diode contacts and the ROICs to provide electrical connection. The hybrid detector arrays were placed in leadless chip carriers, wirebonded, and connected to commercially available drive and readout circuitry. Images of UV scenes were focused onto the arrays using fused quartz lenses. These images and movies were successfully collected at frame rates up to 240 Hz using both 32 x 32 and 128 x 128 III-V nitride based UV photodiode imagers.

  6. Electronic structure and v alence of Mn imputiries in III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Schulthess, T. C.; Temmerman, W.; Szotek, Z.; Stocks, G. M.; Butler, W. H.

    2004-03-01

    Substitutional Mn impurities in III-V semiconductors can acquire either a divalent or a trivalent configuration. For example, it is generally accepted that Mn in GaAs is in a (d^5+h) configuration with five occupied Mn d-orbitals and a delocalized hole in the valence band. In contrast, Mn in GaN is believed to be in a d^4 configuration with a deep impurity state that has d-character. But there have recently been some discussions about the possibility of having some Mn ion in GaN assuming a divalent (d^5+h) type configuration. In order to achieve carrier induced ferromagnetism, the desired state of the Mn ions in III-V semiconductors is the (d^5+h) configuration. We have therefore performed ab-initio calculations of the Mn valence when it substitutes Ga in various III-V semiconductor hosts. We use the self-interaction corrected local spin density (SIC-LSD) method which is able to treat localized impurity orbitals properly. In particular we find that the method is capable of predicting the (d^5+h) state of Mn in GaAs. For Mn in GaP and GaN the calculations predict a trivalent d^4 state in the idealized system. The energy differences between d^4 and (d^5+h) configurations in GaP are, however, very small. Introduction of defects or donors doe change the valence of Mn in GaP, favoring the divalent state under certain circumstances. Work supported by the Defense Advanced Research Project Agency and by the Division of Materials Science and Engineering, U.S. Department of Energy, under Contract DE-AC05-00OR22725 with UT-Battelle LLC.

  7. Optically controlled characteristics of III–V Nitride based MM-wave transit-time devices

    Microsoft Academic Search

    Moumita Mukherjee

    2009-01-01

    Extensive simulation experiments are carried out for the first time, to study the photo-irradiation effects on the high frequency characteristics of III-V GaN (Gallium Nitride) based Top-Mounted and Flip-Chip IMPATT oscillators at MM-wave window frequency (140.0 GHz). MM-wave properties of un-illuminated GaN IMPATTs are compared with those of conventional Si, GaAs and InP IMPATTs, under similar operating conditions. Superiority of

  8. Extraction of interface state density in oxide/III–V gate stacks

    NASA Astrophysics Data System (ADS)

    Veksler, D.; Bersuker, G.; Madan, H.; Morassi, L.; Verzellesi, G.

    2015-06-01

    Extracted interface trap densities (Dit) in the oxide/III–V gate stacks vary strongly with the utilized measurement procedures and values of device parameters used in the extraction analysis. Such Dit dependency on both selected procedures and parameters compromises unambiguous extraction of energy distributions of defects affecting device characteristics. To overcome this uncertainty, we propose an extraction approach, which combines the essential features of the high–low method and Terman method, allowing us to self-consistently determine Dit distribution along with values of the critical device parameters, effective oxide thickness (EOT) and substrate doping density (Nd).

  9. Vertical bridgman and gradient freeze growth of III-V compound semiconductors

    SciTech Connect

    Bourret, E.D.

    1990-07-01

    Major improvements in the structural and electrical perfection of single crystals of III-V compound semiconductors have been achieved by using new vertical Bridgman-type and vertical gradient freeze techniques. A general review of experimental set-ups used for growth of large diameter crystals of GaP, InP and GaAs is presented. Crystal properties and characteristic features are discussed to illustrate advantages and disadvantages of the vertical Bridgman-type growth techniques. 22 refs., 5 figs.

  10. III-V/silicon photonic integrated circuits for communication and sensing applications

    NASA Astrophysics Data System (ADS)

    Roelkens, Gunther; Keyvaninia, Shahram; Stankovic, Stevan; De Koninck, Yannick; Tassaert, Martijn; Mechet, Pauline; Spuesens, Thijs; Hattasan, N.; Gassenq, A.; Muneeb, M.; Ryckeboer, E.; Ghosh, Samir; Van Thourhout, D.; Baets, R.

    2013-03-01

    In this paper we review our work in the field of heterogeneous integration of III-V semiconductors and non-reciprocal optical materials on a silicon waveguide circuit. We elaborate on the heterogeneous integration technology based on adhesive DVS-BCB die-to-wafer bonding and discuss several device demonstrations. The presented devices are envisioned to be used in photonic integrated circuits for communication applications (telecommunications and optical interconnects) as well as in spectroscopic sensing systems operating in the short-wave infrared wavelength range.

  11. Silicon grating structures for optical fiber interfacing and III-V/silicon opto-electronic components

    NASA Astrophysics Data System (ADS)

    Roelkens, Gunther; Vermeulen, Diedrik; Li, Yanlu; Muneeb, Muhammad; Hattasan, Nannicha; Ryckeboer, Eva; Deconinck, Yannick; Van Thourhout, Dries; Baets, Roel

    2013-02-01

    In this paper, we review our work on efficient, broadband and polarization independent interfaces between a silicon-on-insulator photonic IC and a single-mode optical fiber based on grating structures. The high alignment tolerance and the fact that the optical fiber interface is out-of-plane provide opportunities for easy packaging and wafer-scale testing of the photonic IC. Next to fiber-chip interfaces we will discuss the use of silicon grating structures in III-V on silicon optoelectronic components such as integrated photodetectors and microlasers.

  12. Ultraviolet photosulfidation of III-V compound semiconductors: A new approach to surface passivation

    SciTech Connect

    Ashby, C.I.H.; Zavadil, K.R.; Howard, A.J.; Hammons, B.E.G. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

    1994-05-02

    A new passivation technique for III-V compound semiconductors based on ultraviolet photolysis of elemental sulfur vapor has been developed. Photosulfidation produces a greater increase in the photoluminescence intensity from GaAs samples than that produced by conventional (NH[sub 4])[sub 2]S dip treatments and is more photostable than the conventional wet process. X-ray photoelectron spectroscopy of the photosulfided GaAs surfaces indicate formation of a surface sulfide rather than the disulfide characteristic of the (NH[sub 4])[sub 2]S process.

  13. Ultraviolet photosulfidation of III-V compound semiconductors: A new approach to surface passivation

    NASA Astrophysics Data System (ADS)

    Ashby, Carol I. H.; Zavadil, Kevin R.; Howard, Arnold J.; Hammons, B. E. Gene

    1994-05-01

    A new passivation technique for III-V compound semiconductors based on ultraviolet photolysis of elemental sulfur vapor has been developed. Photosulfidation produces a greater increase in the photoluminescence intensity from GaAs samples than that produced by conventional (NH4)2S dip treatments and is more photostable than the conventional wet process. X-ray photoelectron spectroscopy of the photosulfided GaAs surfaces indicate formation of a surface sulfide rather than the disulfide characteristic of the (NH4)2S process.

  14. 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.

  15. MOVPE growth of dilute nitride III/V semiconductors using all liquid metalorganic precursors

    NASA Astrophysics Data System (ADS)

    Volz, Kerstin; Koch, Jörg; Höhnsdorf, Falko; Kunert, Bernardette; Stolz, Wolfgang

    2009-04-01

    Understanding the growth mechanisms of III/V semiconductors containing dilute amounts of N, like (GaIn)(NAs) is necessary as these materials are promising candidates for the active material in several optoelectronic devices, as lasers and solar cells. As one deals with metastable material systems, growth has to be conducted far away from thermodynamic equilibrium with several characteristics emanating from that. This paper summarizes our present understanding of the growth of dilute nitride materials by metal organic vapour phase epitaxy, using exclusively liquid metalorganic precursors. N-incorporation in III/V semiconductors for Ga(NAs) as a model system is predominantly determined by the competition of the group-V elements. Large dependencies of the N-incorporation on crystal composition as well as on strain are observed. Additionally, there are minor effects of gas-phase reactions of metalorganic precursors. The nitrogen uptake of the quaternary material system (GaIn)(NAs)/GaAs is shown to be dominated by In-induced desorption of the nitrogen from the surface, which results in a decrease of N-content, by increasing growth temperature or lowering growth rate.

  16. Improved adhesion of photoresist to III-V substrates using PECVD carbon films

    NASA Astrophysics Data System (ADS)

    Mancini, David P.; Smith, Steven M.; Hooper, Andrew F.; Talin, A.; Chang, Daniel; Resnick, Douglas J.; Voight, Steven A.

    2002-07-01

    Amorphous PECVD carbon films have been investigated as a means to prepare III-V compound semiconductor substrates for improved photoresist adhesion. Results show that significant improvements in adhesive durability of patterned photoresist occurred for carbon primed GaAs and InGaAs wafers used in conjunction with both i-line and DUV lithography processes. These carbon layers, were 50-100 Angstrom in thickness, and varied in composition and morphology from a nitrogen-doped, diamond-like material (DLC), to a more hydrogen rich, polymer-like material (PLC). Adhesion durability tests performed in baths of ammonium hydroxide (NH4OH) and hydrochloric acid (HCl) in general showed superior performance compared to non-primed substrates. The sole exception was a failure of PLC priming on GaAs wafers used with a DUV anti-reflective coating. This same system, however, was shown to work extremely well when a DLC coating was substituted. Characterization of PLC and DLC films included use of AES, XPS, FTIR, AFM, and contact angle analysis. Results indicate that carbon films passivate III-V oxides, creating a stable, hydrophobic surface. This factor is proposed as a key reason for the improved resistance to aggressive aqueous environments. AFM results show that carbon films are extremely smooth and actually decrease surface roughness, indicating that mechanical adhesion is unlikely.

  17. GaP-nucleation on exact Si (0 0 1) substrates for III/V device integration

    NASA Astrophysics Data System (ADS)

    Volz, Kerstin; Beyer, Andreas; Witte, Wiebke; Ohlmann, Jens; Németh, Igor; Kunert, Bernardette; Stolz, Wolfgang

    2011-01-01

    This paper summarizes our present knowledge of the defect-free nucleation of III/V semiconductors on exactly oriented Si (0 0 1) surfaces. A defect-free III/V nucleation layer on Si (0 0 1) substrates is important for integrating optoelectronic functions on Si substrates, like III/V-based lasers and solar cells as well as high-mobility III/V-n-channel layers. For applications which rely on CMOS processing and devices, one should choose (0 0 1) Si substrates with no intentional off-cut (exactly oriented ±0.5°). Under high hydrogen pressures and at high annealing temperature, one can maximize the number of double steps even on this Si surface under vapour phase epitaxy (VPE) conditions. A GaP layer free from dislocations, stacking faults, twins and/or antiphase disorder can be grown on a Si homoepitaxial buffer by metal organic vapour phase epitaxy (MOVPE) in a two step process. We show that a thin and low temperature GaP nucleation layer has to be deposited in flow rate modulated growth mode to achieve a charge neutral interface and two-dimensional growth. A GaP layer grown at high temperature on this nucleation layer results in self-annihilation of the remaining antiphase domains. This defect-free GaP layer with a total thickness of only about 50 nm can serve as a template for subsequent integration of III/V device structures on Si (0 0 1) substrates.

  18. Ultraviolet photosulfidation of III-V compound semiconductors for electronic passivation

    SciTech Connect

    Zavadil, K.R.; Ashby, C.I.H.; Howard, A.J.; Hammons, B.E.

    1993-10-01

    A new vacuum-compatible passivation technique for III-V compound semiconductors has been developed. Sulfur passivation of GaAs(100) is produced by ultraviolet photolytic deposition of a sulfide species from vapor phase elemental sulfur. Photoluminescence studies of the photosulfided GaAs reveal a degree of passivation greater than or equal to that produced by conventional (NH{sub 4}{sub 2}S) solution treatment. X-ray Photoelectron Spectroscopy has shown that the sulfur resides on the surface as a single reduced sulfur species, either as sulfide of disulfide, indicating complete fragmentation of the S{sub 8} ring by UV light in proximity to the surface. The degree of photosulfidation depends strongly on surface preparation as demonstrated by the described surface oxide removal studies.

  19. 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. (Purdue Univ., Lafayette, IN (United States))

    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.

  20. Theoretical prediction of topological insulators in thallium-based III-V-VI2 ternary chalcogenides

    NASA Astrophysics Data System (ADS)

    Yan, Binghai; Liu, Chao-Xing; Zhang, Hai-Jun; Yam, Chi-Yung; Qi, Xiao-Liang; Frauenheim, Thomas; Zhang, Shou-Cheng

    2010-05-01

    We predict a new class of three-dimensional topological insulators in thallium-based III-V-VI2 ternary chalcogenides, including TlBiQ2 and TlSbQ2 (Q=Te, Se and S). These topological insulators have robust and simple surface states consisting of a single Dirac cone at the ? point. The mechanism for topological insulating behavior is elucidated using both first-principle calculations and effective field theory models. Remarkably, one topological insulator in this class, TlBiTe2, is also a superconductor when doped with p-type carriers. We discuss the possibility that this material could be a topological superconductor. Another material, TlSbS2, is on the border between topological insulator and trivial insulator phases, in which a topological phase transition can be driven by pressure.

  1. Towards a low noise class-A hybrid III-V/silicon laser

    NASA Astrophysics Data System (ADS)

    Girard, Nils; Baili, Ghaya; Nouchi, Pascale; Dolfi, Daniel; Le Liepvre, Alban; Accard, Alain; Kaspar, Peter; Make, Dalila; Charbonnier, Philippe; Mallecot, Franck; Faugeron, Mickael; Van Dijk, Frederic; Duan, Guang-Hua; Olivier, Ségolène; Malhouitre, Stephan; Kopp, Christophe

    2014-05-01

    We describe a hybrid III-V on Silicon laser designed for low noise class-A dynamics. The laser is based on an InP active region and a passive silicon region integrated in a long laser cavity. High-Q ring resonators are used as optical filters in order to achieve single frequency operation. A fiber-coupled output power of 4.6 mW and a 55 dB side mode suppression ratio are obtained. For a pumping rate of 5.2, the hybrid laser exhibits a Relative Intensity Noise below -145 dB/Hz over a wide frequency bandwidth, from 100 MHz to 40 GHz but still suffers from some noise excess due to relaxation oscillations phenomena and side modes noise. The optimization of the laser cavity design is discussed in order to reach class-A dynamics while reducing residual noise excess.

  2. Generation of Low Emtttance Beams Using Iii-V Semiconductor Photocathodes in AN RF Gun

    NASA Astrophysics Data System (ADS)

    Clendenin, J. E.; Kotseroglou, T.; Mulhollan, G. A.; Palmer, D. T.; Schmerge, J. F.

    2000-12-01

    Normalized rms emittances well below 10-6 m (with thermal emittance ignored) are now predicted for a 1-nC, 10-ps, flattop beam wing an S-band if gun. The expected thermal emittance of a Cu cathode excited at 263 nm is shown to be ~0.3 × 10-6 m, which is potentially a serious limit on the overall minimum emittance. For GaAs, the photoelectron energy parallel to the emitting surface is now known as a function of the perpendicular energy. By adjusting the vacuum level for the semiconductor, it appears that the thermal emittance can be reduced (compared to Cu) by a factor of 2--even more if the cathode is cooled. The prospects for operating an rf gun with a III-V semiconductor photocathode such as GaAs is summarized.

  3. 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. PMID:25490479

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

    SciTech Connect

    Lundstrom, M.S.; Melloch, M.R.; Lush, G.B.; Patkar, M.P.; Young, M.P. (Purdue Univ., Lafayette, IN (United States))

    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.

  5. Radiative dark current in optically thin III-V photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Welser, Roger E.; Sood, Ashok K.; Tatavarti, Sudersena Rao; Wibowo, Andree; Wilt, David M.; Howard, Alex

    2015-03-01

    High-voltage InGaAs quantum well solar cells have been demonstrated in a thin-film format, utilizing structures that employ advanced band gap engineering to suppress non-radiative recombination and expose the limiting radiative component of the diode current. In particular, multiple InGaAs quantum well structures fabricated via epitaxial lift-off exhibit one-sun open circuit voltages as high as 1.05 V. The dark diode characteristics of these high-voltage III-V photovoltaic devices are compared to the radiative current calculated from the measured external quantum efficiency using a generalized detailed balance model specifically adapted for optically-thin absorber structures. The fitted n=1 component of the diode current is found to match the calculated radiative dark current when assuming negligible photon recycling, suggesting this thin-film multiple quantum well structure is operating close to the radiative limit.

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

    PubMed

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

    2015-12-01

    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. PMID:26123270

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

    SciTech Connect

    Ahrenkiel, Scott Phillip [South Dakota School of Mines & Technology] [South Dakota School of Mines & Technology

    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.

  8. Ultraviolet photosulfidation of III--V compound semiconductors for electronic passivation

    SciTech Connect

    Zavadil, K.R.; Ashby, C.I.H.; Howard, A.J.; Hammons, B.E. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

    1994-07-01

    A new vacuum-compatible passivation technique for III--V compound semiconductors has been developed. Sulfur passivation of GaAs(100) is produced by ultraviolet photolytic deposition of a sulfide species from vapor phase elemental sulfur. Photoluminescence studies of the photosulfided GaAs reveal a degree of passivation greater than or equal to that produced by conventional (NH[sub 4])[sub 2]S solution treatments. X-ray photoelectron spectroscopy has shown that the sulfur resides on the surface as a single reduced sulfur species, either as sulfide or disulfide, indicating complete fragmentation of the S[sub 8] ring by UV light in proximity to the surface. The degree of photosulfidation depends strongly on surface preparation as demonstrated by the described surface oxide removal studies.

  9. Hybrid III-V/silicon laser with laterally coupled Bragg grating.

    PubMed

    Cao, Yu-Lian; Hu, Xiao-Nan; Luo, Xian-Shu; Song, Jun-Feng; Cheng, Yuanbing; Li, Cheng-Ming; Liu, Chong-Yang; Wang, Hong; Tsung-Yang, Liow; Lo, Guo-Qiang; Wang, QiJie

    2015-04-01

    In this paper, we demonstrate a compact electrically pumped distributed-feedback hybrid III-V/silicon laser with laterally coupled Bragg grating for the first time to the best of our knowledge. The hybrid laser structure consists of AlGaInAs/InP multi-quantum-well gain layers on top of a laterally corrugated silicon waveguide patterned on a silicon on insulator (SOI) substrate. A pair of surface couplers is integrated at the two ends of the silicon waveguide for the optical coupling and characterization of the ouput light. Single wavelength emission of ~1.55µm with a side-mode-suppression- ratio larger than 20dB and low threshold current density of 1.54kA/cm2 were achieved for the device under pulsed operation at 20 °C. PMID:25968717

  10. Ab initio synthesis of single-layer III-V materials

    NASA Astrophysics Data System (ADS)

    Singh, Arunima K.; Zhuang, Houlong L.; Hennig, Richard G.

    2014-06-01

    The discovery of a novel material requires the identification of the material's composition as well as of suitable synthesis conditions. We present a data-mining approach to identify suitable substrates for the growth of two-dimensional materials and apply the method to the recently predicted two-dimensional III-V compounds. We identify several lattice-matched substrates for their epitaxial growth, stabilization, and functionalization. Density-functional calculations show that these substrates sufficiently reduce the formation energies of the metastable two-dimensional materials to make them thermodynamically stable. We show that chemical interactions of the two-dimensional materials with the substrates shift the Fermi level of these materials, resulting in doping. The large adsorption energies and strong doping indicate that these metals should provide good electrical contact to enable transport measurements and electronic applications.

  11. Nucleation and growth of dielectric films on III-V semiconductors during atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Granados Alpizar, Bernal

    In order to continue with metal-oxide-semiconductors (CMOS) transistor scaling and to reduce the power density, the channel should be replaced with a material having a higher electron mobility, such as a III-V semiconductor. However, the integration of III-V's is a challenge because these materials oxidize rapidly when exposed to air and the native oxide produced is characterized by a high density of defects. Deposition of high-k materials on III-V semiconductors using Atomic Layer Deposition (ALD) reduces the thickness of these oxides, improving the semiconductor/oxide interface quality and the transistor electrical characteristics. In this work, ALD is used to deposit two dielectrics, Al 2O3 and TiO2, on two III-V materials, GaAs and InGaAs, and in-situ X-ray photoelectron spectroscopy (XPS) and in-situ thermal programmed desorption (TPD) are used for interface characterization. Hydrofluoric acid (HF) etching of GaAs(100) and brief reoxidation in air produces a 9.0 ±1.6 Å-thick oxide overlayer containing 86% As oxides. The oxides are removed by 1 s pulses of trimethylaluminum (TMA) or TiCl4. TMA removes the oxide overlayer while depositing a 7.5 ± 1.6 Å thick aluminum oxide. The reaction follows a ligand exchange mechanism producing nonvolatile Al-O species that remain on the surface. TiCl4 exposure removes the oxide overlayer in the temperature range 89°C to 300°C, depositing approximately 0.04 monolayer of titanium oxide for deposition temperatures from 89°C to 135°C, but no titanium oxide is present from 170 °C to 230 °C. TiCl4 forms a volatile oxychloride product and removes O from the surface while leaving Cl atoms adsorbed to an elemental As layer, chemically passivating the surface. The native oxide of In0.53Ga0.47As(100) is removed using liquid HF and gas phase HF before deposition of Al2O3 using TMA and H2O at 170 °C. An aluminium oxide film with a thickness of 7.2 ± 1.2 Å and 7.3 ± 1.2 Å is deposited during the first pulse of TMA on liquid and gas phase HF treated samples, respectively. After three complete ALD cycles the thickness of the aluminum oxide film is 10.0 ± 1.2 Å on liquid HF treated and 6.6 ± 1.2 Å on gas phase HF treated surfaces. Samples treated with gas phase HF inhibit growth. Inhibition is caused by residual F atoms that passivate the surface and by surface poisoning due to the thicker carbon film deposited during the first pulse of TMA. On InGaAs covered by native oxide, the first TMA pulse deposits 9 Å of aluminum oxide, and reaches saturation at 13 Å after 15 pulses of TMA. The film grows by scavenging oxygen from the substrate oxides. Substrate oxides are reduced by the first pulse of TMA even at 0°C. At 0°C, on a 9 Å thick Ga-rich oxide surface, 1 pulse of TMA mainly physisorbs and a limited amount of aluminum oxide is deposited. At 0°C, 110°C, and 170°C, more aluminum oxide is deposited on surfaces initially containing As oxide, and larger binding energy (BE) shifts of the O 1s peak are observed compared to surfaces that contain Ga oxides only, showing that As oxides improve the nucleation of Al2O 3.

  12. Compact modeling of the shift between classical and quantum threshold voltages in a III-V nanowire

    NASA Astrophysics Data System (ADS)

    Hiblot, G.; Rafhay, Q.; Boeuf, F.; Ghibaudo, G.

    2014-10-01

    In this work, a quantum correction model for the threshold voltage of cylindrical nanowires is presented. Using a cylindrical self-consistent 1-D Poisson-Schrödinger (PS) numerical resolution of the charge profile as a reference, a generalized and compact Hänsch’s formula is proposed and systematically validated on simulation. As an example of application, this equation is then applied to III-V nanowires and to the study of the threshold voltage variability of these devices. The results suggest an increased variability due to the small mass of III-V semiconductors and to the larger quantum confinement of nanowire architectures.

  13. Analytical theory of the anisotropy of the conduction band in III-V semiconductors in a strong magnetic field

    NASA Astrophysics Data System (ADS)

    Alekseev, P. S.

    2009-09-01

    Corrections from the K 3 Dresselhaus term cubic in the wave vector to the energies of the ground and first excited Landau levels in III-V semiconductors have been analyzed. The calculated corrections together with the known corrections from the K 4 terms in the Hamiltonian of an electron provide a complete analytical description of the anisotropy of the conduction-band vertex of the III-V semiconductors in an ultraquantum magnetic field. The performed analysis of the experimental data on the splitting of the cyclotron resonance line in GaAs confirms the reality of the anisotropy mechanism under investigation.

  14. 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.

  15. Use of 3-aminopropyltriethoxysilane deposited from aqueous solution for surface modification of III-V materials

    NASA Astrophysics Data System (ADS)

    Knorr, Daniel B., Jr.; Williams, Kristen S.; Baril, Neil F.; Weiland, Conan; Andzelm, Jan W.; Lenhart, Joseph L.; Woicik, Joseph C.; Fischer, Daniel A.; Tidrow, Meimei Z.; Bandara, Sumith V.; Henry, Nathan C.

    2014-11-01

    Focal plane arrays of strained layer superlattices (SLSs) composed of InAs/GaSb are excellent candidates for infrared imaging, but one key factor limiting their utility is the lack of a surface passivation technique capable of protecting the mesa sidewall from degradation. Along these lines, we demonstrate the use of aqueous 3-aminopropyl triethoxysilane (APTES) deposited as a surface functionalizing agent for subsequent polymer passivation on InAs and GaSb surfaces following a HCl/citric acid procedure to remove the conductive oxide In2O3. Using atomic force microscopy, variable angle spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS), and modeling with density functional theory (DFT), we demonstrate that APTES films can successfully be deposited on III-V substrates by spin coating and directly compare these films to those deposited on silicon substrates. The HCl/citric acid surface preparation treatment is particularly effective at removing In2O3 without the surface segregation of In oxides observed from use of HCl alone. However, HCl/citric acid surface treatment method does result in heavy oxidation of both Ga and Sb, accompanied by segregation of Ga oxide to the surface. Deposited APTES layer thickness did not depend on the substrate choice, and thicknesses between 1 and 20 nm were obtained for APTES solution concentrations ranging from 0.1 to 2.5 vol %. XPS results for the N1s band of APTES showed that the content of ionic nitrogen was high (?50%) for the thinnest films (?1 nm), and decreased with increasing film thickness. These results indicate that APTES can indeed be used to form a silane surface layer to cover III-V materials substrates. Such APTES silane layers may prove useful in surface passivation of these materials alone, or as surface functionalizing agents for subsequent covalent binding with polymer overlayers like polyimide.

  16. Improved performance III-V quantum well IR photodetectors: review of current and potential focal plane technology

    Microsoft Academic Search

    Lewis T. Claiborne

    1997-01-01

    The maturation of the III-V materials technology has provided an opportunity for the development of a producible and affordable class of IR detector arrays. Designs based on the GaAs compounds permit the realization of multiple quantum well IR photodetectors (QWIPs) which are useful for long wavelength focal plane arrays with sizes demonstrated up to 640 X 480. Similar designs using

  17. Computor control of maskless ion implanter with Au-Si-Be LM ion source for III-V compound semiconductors

    Microsoft Academic Search

    Eizo Miyauchi; Hiroshi Arimoto; Yasuo Bamba; Akira Takamori; Hisao Hashimoto

    1985-01-01

    We have developed a microcomputer control system to operate a 100 kV maskless ion implanter for III-V compound semiconductors. The performances of various functions of this computer-controlled ion implanter has been tested. Ion species switching by an E × B mass filter, ion beam diameter monitoring, ion beam mark detection, and ion beam writing by controlling E × B mass

  18. A test bench for accelerated thermal ageing of III–V concentration solar cells using forward bias injection

    Microsoft Academic Search

    Fabio Immovilli; Claudio Bianchini; Alberto Bellini; Andrea Sala

    2011-01-01

    Power production from solar photovoltaic systems is constantly increasing. In the last few years concentration photovoltaic (CPV) system using III-V multijunction cells ap- peared on the market, promising doubled efficiencies compared to traditional silicon PV solar panels. For CPV systems to be competitive on the market, they must be reliable to assure long- term operation. This paper presents the design

  19. Performance analysis of III–V triple-junction concentrator solar cells under varying temperature and intensity

    Microsoft Academic Search

    V. K. Narasimhan; C. E. Valdivia; N. Yastrebova; J. Fafard; V. Tatsiankou; F. Lejean; T. J. Hall; K. Hinzer

    2008-01-01

    We discuss intensity and temperature effects on solar cell performance. We simulate and measure these effects in III-V triple-junction concentrator cells incorporating quantum dots under AM1.5D illumination. Reducing series resistance improved simulated efficiency by 4.3%, and improving sub-cell design reduced power degradation with increasing temperature.

  20. LATTICE THERMAL CONDUCTIVITY OF p-TYPE III-V SEMICONDUCTORS AND p-Si AT LOW TEMPERATURES

    E-print Network

    Paris-Sud XI, Université de

    571 LATTICE THERMAL CONDUCTIVITY OF p-TYPE III-V SEMICONDUCTORS AND p-Si AT LOW TEMPERATURES M at low temperatures. This has been observed as a strong decrease in the thermal conductivity of Ge and Si thermal conductivity results of the p-type Ge and Si have been explained by Suzuki and Mikoshiba [23

  1. Self-aligned via and trench for metal contact in III-V semiconductor devices Jun Fei Zhenga

    E-print Network

    Demir, Hilmi Volkan

    and trench structures in III-V semiconductor devices in particular, on InP platform is presented, together of the device epitaxial layers e.g., InP on an InGaAs etch stop , both laid down on the device layers before as a part of the patterned structures and is, therefore, perfectly self-aligned. By selectively removing

  2. 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 potential for net gains in efficiency at high concentration.

  3. 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. [Sandia National Labs., Albuquerque, NM (United States); Foster, C. [Indiana University Cyclotron Facility, Bloomington, IN (United States)

    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)].

  4. Passively mode-locked III-V/silicon laser with continuous-wave optical injection.

    PubMed

    Cheng, Yuanbing; Luo, Xianshu; Song, Junfeng; Liow, Tsung-Yang; Lo, Guo-Qiang; Cao, Yulian; Hu, Xiaonan; Li, Xiaohui; Lim, Peng Huei; Wang, Qi Jie

    2015-03-01

    We demonstrate electrically pumped two-section mode locked quantum well lasers emitting at the L-band of telecommunication wavelength on silicon utilizing die to wafer bonding techniques. The mode locked lasers generate pulses at a repetition frequency of 30 GHz with signal to noise ratio above 30 dB and 1 mW average output power per facet. Optical injection-locking scheme was used to improve the noise properties of the pulse trains of passively mode-locked laser. The phases of the mode-locked frequency comb are shown to be coherent with that of the master continuous-wave (CW) laser. The radio-frequency (RF)-line-width is reduced from 7.6 MHz to 150 kHz under CW optical injection. The corresponding pulse-to-pulse jitter and integrated RMS jitter are 29.7 fs/cycle and 1.0 ps, respectively. The experimental results demonstrate that optical injection can reduce the noise properties of the passively mode locked III-V/Si laser in terms of frequency linewidth and timing jitter, which makes the devices attractive for photonic analog-to-digital converters and clock generation and recovery. PMID:25836859

  5. 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 ?s and 100 ns respectively in a 2 ?m 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.

  6. Compositional and Structural Characterization by TEM of Lattice-Mismatched III-V Epilayers

    SciTech Connect

    Ahrenkiel, S. P.; Rathi, M.; Nesheim, R.; Zheng, N.; Vunnam, S.; Carapella, J. J.; Wanlass, M. W.

    2011-01-01

    We discuss compositional and structural transmission electron microscopy (TEM) characterization of lattice-mismatched (LMM) III-V epilayers grown on GaAs by metalorganic chemical vapor deposition (MOCVD), with possible applications in high-efficiency multijunction solar cells. In addition to the use of TEM imaging to survey layer thicknesses and defect morphology, our analysis emphasizes the particular methods of energy-dispersive X-ray spectrometry (EDX) and convergent-beam electron diffraction (CBED). Outlined here is a standards-based method for extracting compositions by EDX, which uses principal-component analysis (PCA) [1], combined with the zeta-factor approach of Watanabe and Williams [2]. A procedure is described that uses the coordinates of high-order Laue zone (HOLZ) lines, which are found in the bright-field disks of CBED patterns, to extract composition and strain parameters from embedded epilayers. The majority of the crystal growth for this work was performed at NREL, which has accommodated the development at SDSM&T of the characterization techniques described. However, epilayer deposition capability at SDSM&T has recently been achieved, using a home-built system, which is presently being used to examine new lattice-mismatched structures relevant to photovoltaic technology.

  7. New Materials for Future Generations of III-V Solar Cells

    SciTech Connect

    Geisz, J. F.; Friedman, D. J.; Olson, J. M.; Kramer, C.; Kibbler, A.; Kurtz, S. R.

    1998-10-06

    Three- and four-junction III-V devices are proposed for ultrahigh-efficiency solar cells using a new 1-eV material lattice-matched to GaAs, namely, GaInNAs. We demonstrate working prototypes of a GaInNAs-based solar cell lattice-matched to GaAs with photoresponse down to 1 eV. Under the AM1.5 direct spectrum with all the light higher in energy than the GaAs band gap filtered out, the prototypes grown with base doping of about 10{sup 17} cm-3 have open-circuit voltages ranging from 0.35 to 0.44 V, short-circuit current densities of 1.8 mA/cm2, and fill factors from 61% to 66%. To improve on the current record-efficiency tandem GaInP/GaAs solar cell by adding a GaInNAs junction, the short-circuit current density of this 1-eV cell must be significantly increased. Because these low short-circuit current densities are due to short diffusion lengths, we have demonstrated a depletion-width-enhanced variation of one of the prototype devices that trades off decreased voltage for increased photocurrent, with a short-circuit current density of 7.4 mA/cm2 and an open-circuit voltage of 0.28 V.

  8. 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%.

  9. 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).

  10. Exploring cryogenic focused ion beam milling as a Group III-V device fabrication tool

    NASA Astrophysics Data System (ADS)

    Dolph, Melissa Commisso; Santeufemio, Christopher

    2014-06-01

    In this paper, we compare the features observed on a Group III-V strained layer superlattice (SLS) materials system as a result of room temperature Ga+ focused ion beam (FIB) milling to the features observed as a result of cryogenic FIB (cryo-FIB) milling at -135 °C under the same beam conditions (30 kV:1 nA). The features on the cryo-FIB milled material were observed both when the material was still cold and after it returned to room temperature. Although cryo-FIB milling yielded patterned features that were initially cleaner than comparable features defined by FIB milling at room temperature, we found that both room temperature FIB milling and cryo-FIB milling with subsequent sample warm-up resulted in the formation of Group III enriched features. These findings suggest that the structural and chemical properties of features fabricated by cryo-FIB milling are temperature-dependent, which is an important consideration when it comes to device fabrication. These dependencies will need to be better understood and controlled if cryo-FIB milling is to have future applications in this area.

  11. 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. PMID:23037542

  12. High-Temperature Thermoelectric Characterization of III-V Semiconductor Thin Films by Oxide Bonding

    NASA Astrophysics Data System (ADS)

    Bahk, Je-Hyeong; Zeng, Gehong; Zide, Joshua M. O.; Lu, Hong; Singh, Rajeev; Liang, Di; Ramu, Ashok T.; Burke, Peter; Bian, Zhixi; Gossard, Arthur C.; Shakouri, Ali; Bowers, John E.

    2010-08-01

    A device fabrication and measurement method utilizing a SiO2-SiO2 covalent bonding technique is presented for high-temperature thermoelectric characterization of thin-film III-V semiconductor materials that suffer from the side-effect of substrate conduction at high temperatures. The proposed method includes complete substrate removal, high-temperature surface passivation, and metallization with a Ti-W-N diffusion barrier. A thermoelectric material, thin-film ErAs:InGaAlAs metal/semiconductor nanocomposite grown on a lattice-matched InP substrate by molecular beam epitaxy, was transferred onto a sapphire substrate using the oxide bonding technique at 300°C, and its original InP substrate, which is conductive at high temperatures, was removed. Electrical conductivities and Seebeck coefficients were measured from room temperature to 840 K for this material on both the InP and sapphire substrates, and the measurement results clearly show that the InP substrate effect was eliminated for the sample on the sapphire substrate. A strain experiment has been conducted to investigate the effect of strain on electrical conductivity.

  13. Structural properties of bismuth-bearing semiconductor alloys

    Microsoft Academic Search

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

    1988-01-01

    Materials currently used for detection in the infrared spectral region have notoriously poor structural properties. In search of a better narrow-gap material, we have addressed the structural properties of bismuth-bearing III-V semiconductor alloys theoretically. Because the Bi compounds are not known to form zinc-blende structures, only the anion-substituted alloys InPBi, InAsBi, and InSbBi are considered candidates as narrow-gap semiconductors. We

  14. Gold-Free Ternary III–V Antimonide Nanowire Arrays on Silicon: Twin-Free down to the First Bilayer

    PubMed Central

    2013-01-01

    With the continued maturation of III–V nanowire research, expectations of material quality should be concomitantly raised. Ideally, III–V nanowires integrated on silicon should be entirely free of extended planar defects such as twins, stacking faults, or polytypism, position-controlled for convenient device processing, and gold-free for compatibility with standard complementary metal–oxide–semiconductor (CMOS) processing tools. Here we demonstrate large area vertical GaAsxSb1–x nanowire arrays grown on silicon (111) by molecular beam epitaxy. The nanowires’ complex faceting, pure zinc blende crystal structure, and composition are mapped using characterization techniques both at the nanoscale and in large-area ensembles. We prove unambiguously that these gold-free nanowires are entirely twin-free down to the first bilayer and reveal their three-dimensional composition evolution, paving the way for novel infrared devices integrated directly on the cost-effective Si platform. PMID:24329502

  15. Phase diagrams and optical properties of phosphide, arsenide, and antimonide binary and ternary III-V nanoalloys

    NASA Astrophysics Data System (ADS)

    Guisbiers, G.; Wautelet, M.; Buchaillot, L.

    2009-04-01

    We report a theoretical investigation, at the nanoscale, free of any adjustable parameters, concerning the size, shape, composition, and segregation effects on the melting temperature and energy band gap of zinc-blende III-V semiconductors. The corresponding nanophase diagram is established. From it, the composition and segregation effects on the energy band gap of the ternary semiconducting nanoalloy are deduced. Moreover, the liquid surface energies for AlP, GaP, AlAs, and AlSb have been calculated ( 0.566±0.060 , 0.510±0.060 , 0.506±0.060J/m2 , and 0.441±0.060J/m2 , respectively). The information obtained in this study can be used to tune the thermo-optical properties of III-V nanomaterials in nano-optoelectronics.

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

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.

    2015-05-01

    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.

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

    PubMed

    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. PMID:26026456

  18. A survey of ohmic contacts to III-V compound semiconductors

    SciTech Connect

    Baca, A.G.; Zolper, J.C.; Briggs, R.D. [Sandia National Labs., Albuquerque, NM (United States); Ren, F. [Lucent Technologies, Murray Hill, NJ (United States); Pearton, S.J. [Univ. of Florida, Gainesville, FL (United States)

    1997-04-01

    A survey of ohmic contact materials and properties to GaAs, InP, GaN will be presented along with critical issues pertaining to each semiconductor material. Au-based alloys (e.g., GeAuNi for n-type GaAs) are the most commonly used contacts for GaAs and InP materials for both n- and p-type contacts due to the excellent contact resistivity, reliability, and usefulness over a wide range of doping levels. Research into new contacting schemes for these materials has focused on addressing limitations of the conventional Au-alloys in thermal stability, propensity for spiking, poor edge definition, and new approaches for a non-alloyed contact. The alternative contacts to GaAs and InP include alloys with higher temperature stability, contacts based on solid phase regrowth, and contacts that react with the substrate to form lower bandgap semiconductors alloys at the interface. A new area of contact studies is for the wide bandgap group III-Nitride materials. At present, low resistivity ohmic contact to p-type GaN has not been obtained primarily due to the large acceptor ionization energy and the resultant difficulty in achieving high free hole concentrations at room temperature. For n-type GaN, however, significant progress has been reported with reactive Ti-based metalization schemes or the use of graded InGaN layers. The present status of these approaches will be reviewed.

  19. Suitability of III-V [XH4][YH4] materials for hydrogen storage: A density functional study

    Microsoft Academic Search

    Filippo Zuliani; Andreas W. Götz; Célia Fonseca Guerra; Evert Jan Baerends

    2009-01-01

    In the search for novel hydrogen storage media, the III-V hydridic material [NH4][BH4] is a natural candidate. It can store a high wt% of hydrogen and has a favorable volumetric density. Unfortunately it was found to decompose slowly at room temperature. It is of interest to consider chemically related materials, such as the series of [XH4][YH4] ionic solids ( X=B

  20. Critical issues in III-V compound semiconductor epitaxy on group IV (silicon, germanium) substrates for optoelectronic applications

    Microsoft Academic Search

    Robert Michael Sieg

    1998-01-01

    Controlled heteroepitaxy of GaAs onto Ge surfaces is an important enabling technology for high efficiency multi-junction III-V solar cells grown on Ge wafers for space satellite power applications, and is also a critical step in the proposed integration of GaAs devices with Si microelectronics via dislocation-suppressing graded SisbxGesb1-x buffer layers. The close lattice and thermal match between GaAs and Ge

  1. Ferromagnetic Order Induced by Photogenerated Carriers in Magnetic III-V Semiconductor Heterostructures of (In,Mn)As\\/GaSb

    Microsoft Academic Search

    S. Koshihara; A. Oiwa; M. Hirasawa; S. Katsumoto; Y. Iye; C. Urano; H. Takagi; H. Munekata

    1997-01-01

    We report the inducement of a ferromagnetic order by photogenerated carriers in a novel III-V-based magnetic semiconductor heterostructure p-(In,Mn)As\\/GaSb grown by molecular beam epitaxy. At low temperatures \\\\(<35 K\\\\), samples preserve ferromagnetic order even after the light is switched off, whereas they recover their original paramagnetic condition above 35 K. The results are explained in terms of hole transfer from

  2. Orthorhombic Symmetry DX\\/AX Deep Impurity Centers in III-V and II-VI Semiconductors

    Microsoft Academic Search

    James D. Chadi

    1997-01-01

    We have identified a new class of DX and AX centers with orthorhombic symmetry in III-V and II-VI semiconductors. The new centers have many of the properties of trigonally symmetric centers, i.e., the DX (AX) centers are negatively (positively) charged, they give rise to persistent-photoconductivity, and there is a large Stokes shift between the optical and thermal ionization energies. However,

  3. Revised ab initio natural band offsets of all group IV, II-VI, and III-V semiconductors

    Microsoft Academic Search

    Yong-Hua Li; Aron Walsh; Shiyou Chen; Wan-Jian Yin; Ji-Hui Yang; Jingbo Li; Juarez L. F. da Silva; X. G. Gong; Su-Huai Wei

    2009-01-01

    Using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V, and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the reference level volume deformation and offers a more reliable prediction of the ``natural'' unstrained offsets. Comparison is made to experimental

  4. Current conduction in bound-to-miniband transition III-V multiquantum well\\/superlattice infrared photodetectors

    Microsoft Academic Search

    S. S. Li; M. Y. Chuang; L. S. Yu

    1993-01-01

    The use of the optical matrix method for computing the energy states and transmission probability in the bound-to-miniband (BTM) and step-bound-to-miniband (SBTM) transition III-V quantum well infrared photodetectors (QWIPs) is described. The effect of exchange energy due to electron-electron interaction was taken into account in the calculation of the Fermi level in the quantum well. Numerical simulations of the dark

  5. ccsd-00003231,version1-29Nov2004 Long-range ordering of III-V semiconductor

    E-print Network

    Paris-Sud XI, Université de

    ccsd-00003231,version1-29Nov2004 Long-range ordering of III-V semiconductor nanostructures from a GaAs/InAs/InGaAs/GaAs sequence grown on GaAs by metalorganic vapour phase epitaxy at two) that forms, between a thin GaAs layer (on which growth was performed) and a GaAs substrate joined together

  6. Iii-v semiconductor quantum-well lasers and related opto-electronic devices on silicon. Technical report

    Microsoft Academic Search

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

    1989-01-01

    The research goal is to further develop quantum well heterostructure (QWH) lasers and to realize reliable Al(x)Ga(1-x)As-GaAs QWH lasers on Si. In spite of the significant lattice and thermal expansion mismatch between GaAs and Si, the idea of splicing III-V semiconductor technology, i.e., optoelectronics and photonics, onto Si has obvious appeal. Adding to this is the fact, as shown earlier

  7. Method of envelope functions and intervalley ?-X z interaction of states in (001) III–V semiconductor heterostructures

    Microsoft Academic Search

    É. E. Takhtamirov; V. A. Volkov

    2000-01-01

    The kp method is used to analyze the problem of intervalley \\\\Gamma-X_z\\u000ainteraction of conduction band states in the (001) lattice-matched III-V\\u000asemiconductor heterostructures. A convenient basis for expansion of the wave\\u000afunction is systematically selected and a multiband system of equations is\\u000aderived for the envelope functions which is then reduced to a system of three\\u000aequations for three

  8. Method of envelope functions and intervalley ?- X z interaction of states in (001) III–V semiconductor heterostructures

    Microsoft Academic Search

    É. E. Takhtamirov; V. A. Volkov

    2000-01-01

    The kp method is used to analyze the problem of intervalley ?-X\\u000a z interaction of conduction-band states in the (001) lattice-matched III–V semiconductor heterostructures. A convenient basis\\u000a for expansion of the wave function is systematically selected and a multiband system of equations is derived for the envelope\\u000a functions which is then reduced to a system of three equations for three

  9. Method of envelope functions and intervalley \\\\Gamma-X_z interaction of states in (001) III-V semiconductor heterostructures

    Microsoft Academic Search

    E. E. Takhtamirov; V. A. Volkov

    2001-01-01

    The kp method is used to analyze the problem of intervalley \\\\Gamma-X_z interaction of conduction band states in the (001) lattice-matched III-V semiconductor heterostructures. A convenient basis for expansion of the wave function is systematically selected and a multiband system of equations is derived for the envelope functions which is then reduced to a system of three equations for three

  10. Pressure-induced structural change of liquid InAs and the systematics of liquid III-V compounds

    Microsoft Academic Search

    T. Hattori; K. Tsuji; Y. Miyata; T. Sugahara; F. Shimojo

    2007-01-01

    To understand the pressure-induced structural changes of liquid III-V compounds systematically, the pressure dependence of l-InAs was investigated using the synchrotron x-ray diffraction and an ab initio molecular-dynamics simulation (AIMD). The x-ray diffraction experiments revealed that the liquid changes its compression behavior from a nearly uniform type to a nonuniform one around 9GPa . Corresponding to this change, the coordination

  11. Pressure-induced structural change of liquid InAs and the systematics of liquid III-V compounds

    Microsoft Academic Search

    T. Hattori; K. Tsuji; Y. Miyata; T. Sugahara; F. Shimojo

    2007-01-01

    To understand the pressure-induced structural changes of liquid III-V compounds systematically, the pressure dependence of l-InAs was investigated using the synchrotron x-ray diffraction and an ab initio molecular-dynamics simulation (AIMD). The x-ray diffraction experiments revealed that the liquid changes its compression behavior from a nearly uniform type to a nonuniform one around 9 GPa. Corresponding to this change, the coordination

  12. Physics-Based Compact Model for III–V Digital Logic FETs Including Gate Tunneling Leakage and Parasitic Capacitance

    Microsoft Academic Search

    Saeroonter Oh; H.-S. Philip Wong

    2011-01-01

    A physics-based compact model is developed for III-V field-effect transistors for digital logic applications. Quasi- ballistic ratios, trapezoidal quantum-well subband energy levels, and 2-D source\\/drain influence on both electrostatics and capaci- tance are considered. Furthermore, gate tunneling leakage current and parasitic capacitance models are included. These latter effects are important in future technology logic applications, particularly in circuits such as

  13. Revised ab initio natural band offsets of all group IV, II-VI, and III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Li, Yong-Hua; Walsh, Aron; Chen, Shiyou; Yin, Wan-Jian; Yang, Ji-Hui; Li, Jingbo; Da Silva, Juarez L. F.; Gong, X. G.; Wei, Su-Huai

    2009-05-01

    Using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V, and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the reference level volume deformation and offers a more reliable prediction of the "natural" unstrained offsets. Comparison is made to experimental work, where a noticeable improvement is found compared to previous methodologies.

  14. The Genetic Analysis of a Reciprocal Translocation, eT1(III; V), in CAENORHABDITIS ELEGANS

    PubMed Central

    Rosenbluth, Raja E.; Baillie, David L.

    1981-01-01

    The Caenorhabditis elegans mutation e873, which results in a recessive uncoordinated phenotype (formerly named Unc-72) and which had been isolated after 32P treatment (Brenner 1974), has now been found to act as a crossover suppressor and to be associated with a translocation between linkage groups (LG's) III and V. The translocation has been named, eT1(III; V); eT1 acts as a dominant crossover suppressor for both the right half of LGIII and the left half of LGV, providing a balancer for a total of 39 map units. The uncoordinated e873 phenotype has been shown to be a consequence of an inactive unc-36III gene. It was possible to demonstrate that, in translocation heterozygotes, eT1 chromosomes marked with either sma-3 or dpy-11 segregate from normal LGIII, while those marked with bli-5, sma-2 or unc-42 segregate from normal LGV. Since bli-5 and sma-2 are normally on LGIII, and dpy-11 is normally on LGV, it is concluded that: (a) eT1 is a reciprocal translocation; (b) there is a breakpoint between sma-3 and sma-2 in LGIII (the region containing unc-36) and one between dpy-11 and unc-42 in LGV; (c) there is no dominant centromere between sma-2 and bli-5 on LGIII, since in eT1 these genes are not linked to a LGIII centromere. Similarly, it is highly unlikely that there is a centromere to the left of dpy-11 on LGV. The new gene order in eT1 was determined by measuring recombination rates between markers in eT1 homozygotes. It is concluded that the new order is: dpy-1 sma-3 (break) dpy-11 unc-60, and bli-5 sma-2 (break) unc-42 unc-51.—This is the first analysis of a C. elegans translocation with respect to reciprocity, breakpoints and new gene order. PMID:6953041

  15. New materials for future generations of III-V solar cells

    SciTech Connect

    Geisz, J.F.; Friedman, D.J.; Olson, J.M.; Kramer, C.; Kibbler, A.; Kurtz, S.R. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States)

    1999-03-01

    Three- and four-junction III-V devices are proposed for ultrahigh-efficiency solar cells using a new 1-eV material lattice-matched to GaAs, namely, GaInNAs. We demonstrate working prototypes of a GaInNAs-based solar cell lattice-matched to GaAs with photoresponse down to 1 eV. Under the AM1.5 direct spectrum with all the light higher in energy than the GaAs band gap filtered out, the prototypes grown with base doping of about 10{sup 17}&hthinsp;cm{sup {minus}3} have open-circuit voltages ranging from 0.35 to 0.44 V, short-circuit current densities of 1.8 mA/cm{sup 2}, and fill factors from 61{percent} to 66{percent}. To improve on the current record-efficiency tandem GaInP/GaAs solar cell by adding a GaInNAs junction, the short-circuit current density of this 1-eV cell must be significantly increased. Because these low short-circuit current densities are due to short diffusion lengths, we have demonstrated a depletion-width-enhanced variation of one of the prototype devices that trades off decreased voltage for increased photocurrent, with a short-circuit current density of 7.4 mA/cm{sup 2} and an open-circuit voltage of 0.28 V. {copyright} {ital 1999 American Institute of Physics.}

  16. A III-V nanowire channel on silicon for high-performance vertical transistors.

    PubMed

    Tomioka, Katsuhiro; Yoshimura, Masatoshi; Fukui, Takashi

    2012-08-01

    Silicon transistors are expected to have new gate architectures, channel materials and switching mechanisms in ten years' time. The trend in transistor scaling has already led to a change in gate structure from two dimensions to three, used in fin field-effect transistors, to avoid problems inherent in miniaturization such as high off-state leakage current and the short-channel effect. At present, planar and fin architectures using III-V materials, specifically InGaAs, are being explored as alternative fast channels on silicon because of their high electron mobility and high-quality interface with gate dielectrics. The idea of surrounding-gate transistors, in which the gate is wrapped around a nanowire channel to provide the best possible electrostatic gate control, using InGaAs channels on silicon, however, has been less well investigated because of difficulties in integrating free-standing InGaAs nanostructures on silicon. Here we report the position-controlled growth of vertical InGaAs nanowires on silicon without any buffering technique and demonstrate surrounding-gate transistors using InGaAs nanowires and InGaAs/InP/InAlAs/InGaAs core-multishell nanowires as channels. Surrounding-gate transistors using core-multishell nanowire channels with a six-sided, high-electron-mobility transistor structure greatly enhance the on-state current and transconductance while keeping good gate controllability. These devices provide a route to making vertically oriented transistors for the next generation of field-effect transistors and may be useful as building blocks for wireless networks on silicon platforms. PMID:22854778

  17. Optical Properties of Iii-V and II-Vi Strained Semiconductor Heterostructures Under Pressure

    NASA Astrophysics Data System (ADS)

    Hwang, Seon-Ju.

    Scope and method of study. Optical properties of strained heterostructures in III-V and II-VI compounds have been investigated using various optical spectroscopic techniques, such as photoluminescence, photoluminescence excitation, photoreflectance, and photomodulated transmission measurements. Hydrostatic pressure, using a diamond anvil high-pressure cell, has been applied to study the pressure dependence of PL. Findings and conclusions. Pressure induced Gamma-X band crossover has been observed at pressures around 26 kbar in a GaAs/GaAs_{0.68}P_{0.32} strained multiple quantum well (SMQW) sample. With this crossover, the valence band offset ratio in the heterojunction has been determined to be Q_{v} = 0.25. The pressure induced band crossing in other GaAs/GaAs_{1-x}{rm P}_{x} samples was impossible to observe due to a donor-like deep level, which appeared at pressures higher than 17 kbar. The comparison of the experimental results and theoretical calculations showed that the coupling between the light-hole and the split -off band must be included to fit the higher order (n >= 2) interband transitions in InAs _{1 - x}{rm P}_ {x}/InP SMQW's. From the pressure dependent PL results and the ambient pressure PL and PLE spectra, the critical thickness of the CdSe well layer in highly strained CdSe/ZnSe single quantum wells was estimated as less than 4-monolayers which agreed well to the theoretically calculated value. The oscillations in PLE spectra in ZnSe/CdSe single quantum wells (SQW's) are attributed to the Franz -Keldysh effect due to the built-in electric field in the SQW's. The origin of the field is not yet understood. For the first time, pressure dependent PL of cubic GaN has been studied. Pressure coefficients of various transitions have been determined.

  18. III-V semiconductor waveguides for photonic functionality at 780 nm

    NASA Astrophysics Data System (ADS)

    Maclean, Jessica O.; Greenaway, Mark T.; Campion, Richard P.; Pyragius, Tadas; Fromhold, T. Mark; Kent, Anthony J.; Mellor, Christopher J.

    2014-03-01

    Photonic integrated circuits based on III-V semiconductor polarization-maintaining waveguides were designed and fabricated for the first time for application in a compact cold-atom gravimeter1,2 at an operational wavelength of 780 nm. Compared with optical fiber-based components, semiconductor waveguides achieve very compact guiding of optical signals for both passive functions, such as splitting and recombining, and for active functions, such as switching or modulation. Quantum sensors, which have enhanced sensitivity to a physical parameter as a result of their quantum nature, can be made from quantum gases of ultra-cold atoms. A cloud of ultra-cold atoms may start to exhibit quantum-mechanical properties when it is trapped and cooled using laser cooling in a magneto-optical trap, to reach milli-Kelvin temperatures. The work presented here focuses on the design and fabrication of optical devices for a quantum sensor to measure the acceleration of gravity precisely and accurately. In this case the cloud of ultra-cold atoms consists of rubidium (87Rb) atoms and the sensor exploits the hyperfine structure of the D1 transition, from an outer electronic state of 5 2S ½ to 5 2P3/2 which has an energy of 1.589 eV or 780.241 nm. The short wavelength of operation of the devices dictated stringent requirements on the Molecular Beam Epitaxy (MBE) and device fabrication in terms of anisotropy and smoothness of plasma etch processes, cross-wafer uniformities and alignment tolerances. Initial measurements of the optical loss of the polarization-maintaining waveguide, assuming Fresnel reflection losses only at the facets, suggested a loss of 8 dB cm-1, a loss coefficient, ?, of 1.9 (+/-0.3) cm-1.

  19. Lasing characteristics and optical properties of II-VI and III-V semiconductor microdisks

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Hua

    This dissertation focuses on exploring the interaction between confined photons and confined electronic states in new classes of semiconductor microcavities. We apply epitaxial and microfabrication technologies to make semiconductor microstructures that contain embedded nanostructures such as quantum wells and quantum dots. We use optical techniques, such as cryogenic static and dynamic microphotoluminescence, to study the physics of confined photons and confined electronic states in these systems. The first set of experiments focus on ZnSe microdisks containing Zn 0.7Cd0.3Se quantum wells. Unlike the more extensively investigated microcavities based upon the III-V semiconductors, these wide band gap systems are expected to be characterized by stronger excitonic effects. We have developed new protocols for the consistent fabrication of ZnSe microdisks of high structural quality, supported on (Al,Ga)As pedestals. The photoluminescence emission spectrum is dominated by excitonic recombination in the quantum well region. We observe a set of sharp emission lines on the low energy shoulder of the quantum well photoluminescence. We attribute these features to the coupling between exciton emission and the whispering-gallery modes of the microdisk. This inference is consistent with our temperature-dependent measurements. However, power-dependent measurements of these microdisks did not produce any evidence for stimulated emission, even when excited at high optical intensities using pulsed excitation. We conclude that harmful surface recombination may be responsible for these observations. The next set of experiments focus on the steady state and dynamic optical properties of GaAs/(Ga,Al)As microdisk containing interface fluctuation quantum dots. These constitute a departure from previously studied GaAs/(Ga,Al)As microdisk systems that contain self assembled quantum dots. We have developed a new processing protocol for fabricating these microdisks, including a surface passivation technique that greatly enhances the optical properties of these systems. Stimulated emission is achieved in the microdisk cavity using optical excitation. Steady-state measurements of the stimulated emission via whispering gallery modes yield a quality factor Q ˜ 5800 and a coupling constant beta ˜ 0.09. The broad gain spectrum produces mode hopping between spectrally adjacent whispering gallery modes as a function of temperature and excitation power. (Abstract shortened by UMI.)

  20. Role of Surface Reconstruction in Atomic Ordering in (001) Mixed Iii-V Epitaxial Layers

    NASA Astrophysics Data System (ADS)

    Philips, Brett Andrew

    This thesis investigates the influence of surface reconstruction on atomic ordering. In the ordering mechanism proposed, atomic order results from preferential occupation of lattice sites to relieve the strain associated with surface reconstruction and atomic relaxation. Simply due to steric considerations, larger atoms occupy the sites between dimer surface bonds, and the smaller atoms occupy the compressed sites beneath the dimer bonds. A unique inter-planar ordering mechanism was proposed in which the only requisite is that the surface be composed of only dimerized group V atoms at all stages of growth. Growth in the layer-by-layer mode would then result in a correlated shift of all dimers after the passage of the surface step. The resulting ordered microstructure would then be determined by the nature of step flow growth. The efficacy of the intra-planar ordering mechanism has been evaluated by using a valence field model to determine the atomic relaxation induced strains and the interaction of this strain with the preferential incorporation of atomic species differing in their tetrahedral radii. The proposed mechanism has been found to effectively relieve the reconstruction induced strain via preferential incorporation of the species with the larger tetrahedral radii to the dilated sites and those with the smaller tetrahedral radii to the compressed sites beneath the dimer bonds. The proposed mechanism provides a general theory that can explain nearly all of the experimental observation of atomic ordering in III -V semiconductors. Experiments to verify the relationship between surface reconstruction and atomic ordering were carried out and revealed that there is a direct correlation between the reconstruction present on the growth surface and the resulting ordered structure. By growing on the 2 x 4 surface reconstruction, the CuPt_{rm B} structure ordered along either the (111) _{B} or the (111) _{B} direction has been observed. Growth of InGaAs on the 4 x 2 gallium rich surface caused no change in the nature of ordering. However, when InGaAs was grown on the arsenic rich 2 x 3 or 1 x 3 surface reconstruction, the resulting novel ordered structure exhibited a three fold periodicity along the (111) _{A} and (111) _{A} directions. Surface reconstruction induced ordering below the 2 x 3 reconstruction can explain the nature of the triple period ordered structure. (Abstract shortened by UMI.).

  1. Erbium-V semimetal and III-V semiconductor composite materials

    NASA Astrophysics Data System (ADS)

    Hanson, Micah P.

    This work investigates the properties of various Er-V/III-V heterostructures grown by molecular beam epitaxy. Metal/semiconductor composite materials consisting of superlattices containing ErAs particles embedded in GaAs, InGaAs, and GaAsSb as well as ErSb particles in GaSb and in GaAsSb were grown. The various electrical and optical properties of these composite materials are found to be dependent on the size and shape of the embedded nanoparticles as influenced by growth conditions, as well as the surrounding matrix material. Hall measurements were performed to investigate the carrier concentrations in the various samples. In all cases, the Fermi level of the composite material was found to increase with the addition of ErAs or ErSb particles. The degree of this shift was dependent on the lateral size of the particles, with larger particles resulting in a smaller increase in Fermi level. Wavelength dependent transmission and reflection measurements of composite materials indicate large absorption resonance. These features are attributed to resonant plasma oscillations of electrons in the metallic nanoparticles, called surface plasmons. The resonance position decreases in wavelength with increasing lateral area of the particles. The position is also dependent on the matrix with ErSb particles in GaSb having resonances from 2.4-4.5 mum and ErAs particles in GaAs having resonances from 1.3-2.5 mum. Pump-probe photocarrier lifetime measurements are performed at 1.55 mum in GaSb and GaAsSb based samples. The addition of ErAs or ErSb particles is found to decrease the photocarrier lifetime. Very fast sub-picosecond photocarrier lifetimes are achieved. These lifetimes were also found to be dependent on the growth conditions of the ErAs and ErSb particles with larger particles leading to shorter photocarrier lifetimes. Finally, the optical transmission properties of complete ErAs films are investigated. The lower carrier concentration in semimetallic ErAs results in lower free carrier absorption than other metals. The films show a semitransparent window from about 2.4 to 1.2 mum. At the low wavelength end an abrupt absorption edge is attributed to interband transitions in the ErAs, while at the long wavelength end a more gradual decrease in transmission is observed, consistent with free carrier Drude absorption.

  2. Developing high-performance III-V superlattice IRFPAs for defense: challenges and solutions

    NASA Astrophysics Data System (ADS)

    Zheng, Lucy; Tidrow, Meimei; Aitcheson, Leslie; O'Connor, Jerry; Brown, Steven

    2010-04-01

    The antimonide superlattice infrared detector technology program was established to explore new infrared detector materials and technology. The ultimate goal is to enhance the infrared sensor system capability and meet challenging requirements for many applications. Certain applications require large-format focal plane arrays (FPAs) for a wide field of view. These FPAs must be able to detect infrared signatures at long wavelengths, at low infrared background radiation, and with minimal spatial cross talk. Other applications require medium-format pixel, co-registered, dual-band capability with minimal spectral cross talk. Under the technology program, three leading research groups have focused on device architecture design, high-quality material growth and characterization, detector and detector array processing, hybridization, testing, and modeling. Tremendous progress has been made in the past few years. This is reflected in orders-of-magnitude reduction in detector dark-current density and substantial increase in quantum efficiency, as well as the demonstration of good-quality long-wavelength infrared FPAs. Many technical challenges must be overcome to realize the theoretical promise of superlattice infrared materials. These include further reduction in dark current density, growth of optically thick materials for high quantum efficiency, and elimination of FPA processing-related performance degradation. In addition, challenges in long-term research and development cost, superlattice material availability, FPA chip assembly availability, and industry sustainability are also to be met. A new program was established in 2009 with a scope that is different from the existing technology program. Called Fabrication of Superlattice Infrared FPA (FastFPA), this 4-year program sets its goal to establish U.S. industry capability of producing high-quality superlattice wafers and fabricating advanced FPAs. It uses horizontal integration strategy by leveraging existing III-V industry resources and taking advantage of years of valuable experiences amassed by the HgCdTe FPA industry. By end of the program span, three sets of FPAs will be demonstrated-a small-format long-wave FPA, a large-format long-wave FPA, and a medium-format dual-band FPA at long-wave and mid-wave infrared.

  3. X-ray studies of III-V native oxide/gallium arsenide interface

    NASA Astrophysics Data System (ADS)

    Cheong, Seong-Kyun

    Three x-ray techniques have been employed to study wet-thermal native oxides of AlGaAs on GaAs. For these materials, a knowledge of the role of As at the interface is important for understanding Fermi-level pinning and is a central issue in efforts to develop high performance III-V MOSFET devices. This study is focused on how the As is incorporated at the interface, the interfacial strain, and related local structural parameters. X-ray absorption fine-structure spectroscopy (XAFS) was used to determine the site of residual As in wet-oxidized Al0.96Ga0.04As. In a ˜0.5 mum oxide film removed from its GaAs substrate, the remaining As atoms were found to be coordinated with oxygen in the form of amorphous As oxides, with a mixture of ˜80% As3+ and ˜20% As 5+ sites. These two sites are locally similar to As2O 3 and As2O5. Through this measurement, no evidence of interstitial or substitutional As, As precipitates, or GaAs was seen, implying that less than 10% of the As atoms are in these forms. To characterize the oxide structure in both the oxide film and the interfacial region, x-ray reflectivity and reflection-mode XAFS experiments were performed for a thin (300 A) oxidized AlxGa1-xAs (x = 0.96) film grown on GaAs. X-ray reflectivity studies showed that the composition of the surface oxidized film is not homogeneous as a function of depth. Reflection-mode XAFS, which uses the total external reflection of x-rays to confine an x-ray beam to the interfacial region, provided details of the local environment of As atoms at the interface of the oxide/GaAs. Analysis through this technique revealed that As atoms are in the form of mixed As oxides, with the local environment appearing to resemble As2O3 and As 2O5 in the interfacial region, which is consistent with the above observation from the isolated oxide film.

  4. Generalized Valence-Force-Field Model of (Ga,In)(N,P) Ternary Alloys

    SciTech Connect

    Biswas, K.; Franceschetti, A.; Lany, S.

    2008-01-01

    We present a generalized valence-force-field (VFF) model for the ternary III-V alloys (III=Ga, In and V=N, P) to predict the formation energies and atomic structures of ordered and disordered alloy configurations. For each alloy (GaInN, GaInP, GaNP, and InNP) the VFF parameters, which include bond-angle/bond-length interactions, are fitted to the first-principles calculated formation energies of 30 ternary structures. Compared to standard approaches where the VFF parameters are transferred from the individual binary III-V compounds, our generalized VFF approach predicts alloy formation energies and atomic structures with considerably improved accuracy. Using this generalized approach and random realizations in large supercells (4096 atoms), we determine the temperature-composition phase diagram, i.e., the binodal and spinodal decomposition curves, of the (Ga, In) (N, P) ternary alloys.

  5. Steady-State and Transient Electron Transport Within the III–V Nitride Semiconductors, GaN, AlN, and InN: A Review

    Microsoft Academic Search

    Stephen K. O'Leary; Brian E. Foutz; Michael S. Shur; Lester F. Eastman

    2006-01-01

    The III–V nitride semiconductors, gallium nitride, aluminum nitride, and indium nitride, have, for some time now, been recognized\\u000a as promising materials for novel electronic and optoelectronic device applications. As informed device design requires a firm\\u000a grasp of the material properties of the underlying electronic materials, the electron transport that occurs within these III–V\\u000a nitride semiconductors has been the focus of

  6. Specific resistivity of ohmic contacts to n-type direct band-gap III-V compound semiconductors

    NASA Astrophysics Data System (ADS)

    Cho, S. M.; Lee, J. D.; Lee, H. H.

    1991-07-01

    Contact resistivity curves are given in terms of intrinsic barrier height and doping level for ohmic contacts to n-type direct band-gap III-V semiconductor compounds, including AlxGa1-xAs. The results are based on a rigorous treatment of carrier transport across the metal-semiconductor interface. They show that the resistivity behaves quite differently from what might be expected from the usual notion of the effects of doping and barrier height on the resistivity. As such, the results can be used as a useful guide in attempts to lower the contact resistivity.

  7. Crystallographic orientation dependence of impurity incorporation into III-V compound semiconductors grown by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    Makoto Kondo; Chikashi Anayama; Naoko Okada; Hiroshi Sekiguchi; Kay Domen; Toshiyuki Tanahashi

    1994-01-01

    This article presents a comprehensive study of the dependence of impurity incorporation on the crystallographic orientation during metalorganic phase epitaxy of III-V compound semiconductors. We performed doping experiments for group-II impurities (Zn and Mg), group-VI impurities (Se and O), and a group-IV impurity (Si form SiH4 and Si2H6). The host materials were GaAs, Ga(0.5)In(0.5)P, and (Al(0.7)Ga(0.3))(0.5)In(0.5)P grown on GaAs substrates.

  8. Calculated Spin-Orbit Splittings of Some Group IV, III-V, and II-VI Semiconductors

    Microsoft Academic Search

    G. G. Wepfer; T. C. Collins; R. N. Euwema

    1971-01-01

    The spin-orbit splittings of the valence and conduction bands of the group-IV semiconductors Si, Ge, and alpha-Sn, the III-V compounds AlSb, GaP, GaAs, GaSb, InP, InAs, and InSb, and the II-VI compounds ZnS, ZnSe, ZnTe, and CdTe have been obtained at the Gamma, X, and L symmetry points in the Brillouin zone. The calculations were made using a relativistic orthogonalized

  9. In situ TEM observation of synergistic electronic-excitation-effects of phase stability in III-V binary compound nanoparticles

    NASA Astrophysics Data System (ADS)

    Yasuda, H.; Tanaka, A.; Usui, H.; Mori, H.; Lee, J. G.

    2007-07-01

    Electronic-excitation-effects of phase stability in III-V binary compound nanoparticles have been studied by TEM. When GaSb particles were excited by 75 keV electrons, the compound transforms to a two-phase consisting of an antimony core and a gallium shell or an amorphous phase, or remains the original crystalline phase, depending on particle size and/or temperature. It is suggested that such nonlinear responses of the phase stability may arise from synergistic effects of bond instability under excited states, formation of high density of excited states, chemical equilibrium under excited states and temperature dependence of defects mobility.

  10. Effects of Alloy Disorder on Schottky-Barrier Heights 

    E-print Network

    MYLES, CW; REN, SF; Allen, Roland E.; REN, SY.

    1987-01-01

    - ers of the inhomogeneous alloy broadening of deep energy levels due to substitutional impurities in bulk Al, Ga?As (Ref. 11) and Hg, ?Cd Te (Ref. 12) indi- cate that this effect can be of the order of 0.1 eV or greater for some alloy compositions... of antisite defects at the (110) surfaces of ternary III-V semiconductor alloys, A B& C. In these calculations, both the defect and the host were treated in the VCA, which replaces them by their composition-weighted averages. For example, the cation- on...

  11. 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??m thick InP thin-films on Mo foils with ultra-large grain size up to 100??m, 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

  12. Inter-band optoelectronic properties in quantum dot structure of low band gap III-V semiconductors

    SciTech Connect

    Dey, Anup, E-mail: a-dey2002@yahoo.com [Electronics and Communication Engineering Department, Kalyani Government Engineering College, Kalyani 741235 (India); Maiti, Biswajit [Physics Department, Kalyani Government Engineering College, Kalyani 741235 (India); Chanda, Debasree [Department of Engineering and Technological Studies, Kalyani University, Kalyani 741235 (India)

    2014-04-14

    A generalized theory is developed to study inter-band optical absorption coefficient (IOAC) and material gain (MG) in quantum dot structures of narrow gap III-V compound semiconductor considering the wave-vector (k{sup ?}) dependence of the optical transition matrix element. The band structures of these low band gap semiconducting materials with sufficiently separated split-off valance band are frequently described by the three energy band model of Kane. This has been adopted for analysis of the IOAC and MG taking InAs, InSb, Hg{sub 1?x}Cd{sub x}Te, and In{sub 1?x}Ga{sub x}As{sub y}P{sub 1?y} lattice matched to InP, as example of III–V compound semiconductors, having varied split-off energy band compared to their bulk band gap energy. It has been found that magnitude of the IOAC for quantum dots increases with increasing incident photon energy and the lines of absorption are more closely spaced in the three band model of Kane than those with parabolic energy band approximations reflecting the direct the influence of energy band parameters. The results show a significant deviation to the MG spectrum of narrow-gap materials having band nonparabolicity compared to the parabolic band model approximations. The results reflect the important role of valence band split-off energies in these narrow gap semiconductors.

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

    PubMed Central

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

    2014-01-01

    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 ?m, achieved using a single-mode silicon resonator with Q of 106. PMID:24516134

  14. Template-assisted selective epitaxy of III-V nanoscale devices for co-planar heterogeneous integration with Si

    NASA Astrophysics Data System (ADS)

    Schmid, H.; Borg, M.; Moselund, K.; Gignac, L.; Breslin, C. M.; Bruley, J.; Cutaia, D.; Riel, H.

    2015-06-01

    III-V nanoscale devices were monolithically integrated on silicon-on-insulator (SOI) substrates by template-assisted selective epitaxy (TASE) using metal organic chemical vapor deposition. Single crystal III-V (InAs, InGaAs, GaAs) nanostructures, such as nanowires, nanostructures containing constrictions, and cross junctions, as well as 3D stacked nanowires were directly obtained by epitaxial filling of lithographically defined oxide templates. The benefit of TASE is exemplified by the straightforward fabrication of nanoscale Hall structures as well as multiple gate field effect transistors (MuG-FETs) grown co-planar to the SOI layer. Hall measurements on InAs nanowire cross junctions revealed an electron mobility of 5400 cm2/V s, while the alongside fabricated InAs MuG-FETs with ten 55 nm wide, 23 nm thick, and 390 nm long channels exhibit an on current of 660 ?A/?m and a peak transconductance of 1.0 mS/?m at VDS = 0.5 V. These results demonstrate TASE as a promising fabrication approach for heterogeneous material integration on Si.

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

    SciTech Connect

    Daix, N., E-mail: dai@zurich.ibm.com; Uccelli, E.; Czornomaz, L.; Caimi, D.; Rossel, C.; Sousa, M.; Siegwart, H.; Marchiori, C.; Fompeyrine, J. [IBM Research - Zürich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Hartmann, J. M. [CEA, LETI 17, rue des Martyrs, F-38054 Grenoble (France); Shiu, K.-T.; Cheng, C.-W.; Krishnan, M.; Lofaro, M.; Kobayashi, M.; Sadana, D. [IBM T. J. Watson Research Center, 1101 Kitchawan Rd., Route 134 Yorktown Heights, New York 10598 (United States)

    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.

  16. 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 ?m, achieved using a single-mode silicon resonator with Q of 10(6). PMID:24516134

  17. Band-edge diagrams for strained III-V semiconductor quantum wells, wires, and dots

    NASA Astrophysics Data System (ADS)

    Pryor, C. E.; Pistol, M.-E.

    2005-11-01

    We have calculated band-edge energies for most combinations of zinc blende AlN, GaN, InN, GaP, GaAs, InP, InAs, GaSb, and InSb in which one material is strained to the other. Calculations were done for three different geometries (quantum wells, wires, and dots) and mean effective masses were computed in order to estimate confinement energies. For quantum wells, we have also calculated band-edges for ternary alloys. Energy gaps, including confinement, may be easily and accurately estimated using band energies and a simple effective mass approximation, yielding excellent agreement with experimental results. By calculating all material combinations we have identified interesting material combinations, such as artificial donors, that have not been experimentally realized. The calculations were perfomed using strain-dependent k•p theory and provide a comprehensive overview of band structures for strained heterostructures.

  18. 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.

  19. Electron-hole contribution to the apparent s-d exchange interaction in III-V dilute magnetic semiconductors

    NASA Astrophysics Data System (ADS)

    ?liwa, Cezary; Dietl, Tomasz

    2008-10-01

    Spin splitting of photoelectrons in p -type and electrons in n -type III-V Mn-based diluted magnetic semiconductors is studied theoretically. It is demonstrated that the unusual sign and magnitude of the apparent s-d exchange integral reported for GaAs:Mn arises from exchange interactions between electrons and holes bound to Mn acceptors. This interaction dominates over the coupling between electrons and Mn spins, so far regarded as the main source of spin-dependent phenomena. A reduced magnitude of the apparent s-d exchange integral found in n -type materials is explained by the presence of repulsive Coulomb potentials at ionized Mn acceptors and a bottleneck effect.

  20. 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.

  1. 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.

  2. O 2+ versus Cs + for high depth resolution depth profiling of III-V nitride-based semiconductor devices

    NASA Astrophysics Data System (ADS)

    Kachan, M.; Hunter, J.; Kouzminov, D.; Pivovarov, A.; Gu, J.; Stevie, F.; Griffis, D.

    2004-06-01

    Optimum depth resolution with adequate sensitivity for the elements of interest is required to obtain the information desired from SIMS analysis of multilayer nitride III-V structures. For many of the species of interest, particularly the p-type dopants, O 2+ bombardment at low energy is often used. Use of Cs + bombardment and detection of the cesium attachment secondary ions (CsM + where M is the element of interest) may provide several advantages over O 2+ analysis. Using similar low primary ion impact energy analysis conditions for O 2+ and Cs + on CAMECA IMS-6f and IMS-4f instruments, the depth resolution obtained for positive secondary ions is compared.

  3. 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.

  4. Heterogeneously integrated III-V-on-silicon multibandgap superluminescent light-emitting diode with 290 nm optical bandwidth.

    PubMed

    De Groote, A; Peters, J D; Davenport, M L; Heck, M J R; Baets, R; Roelkens, G; Bowers, J E

    2014-08-15

    A broadband superluminescent III-V-on-silicon light-emitting diode (LED) was realized. To achieve the large bandwidth, quantum well intermixing and multiple die bonding of InP on a silicon photonic waveguide circuit were combined for the first time, to the best of our knowledge. The device consists of four sections with different bandgaps, centered around 1300, 1380, 1460, and 1540 nm. The fabricated LEDs were connected on-chip in a serial way, where the light generated in the smaller bandgap sections travels through the larger bandgap sections. By balancing the pump current in the four LEDs, we achieved 292 nm of 3 dB bandwidth and an on-chip power of -8??dBm. PMID:25121874

  5. A physics-based fitting and extrapolation method for measured impact ionization coefficients in III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Chau, Hin-Fai; Pavlidis, Dimitris

    1992-07-01

    A general approach based on a physical model of impact ionization to fit and extrapolate measured ionization coefficients of electrons ? and holes ? in III-V semiconductors is described. Materials being considered include GaAs, AlxGa1-xAs (x=0.1-0.4), InP, In0.53Ga0.47As, and In0.52Al0.48As. Expressions giving the correct dependencies are obtained at very large or small electric fields outside the range of most measurements while at the same time a reasonable fit is achieved for experimental data. The results of the proposed approach yielded a set of physical parameters, which can be coupled with the temperature-dependence relationships in the model to predict impact ionization coefficients over a wide range of electric fields at different temperatures, and can be useful in calculations of temperature-dependent avalanche breakdown voltages of electronic and optical devices.

  6. Conduction-band states and surface core excitons in InSb(110) and other III-V compounds

    NASA Astrophysics Data System (ADS)

    Faul, Jürgen; Neuhold, Georg; Ley, Lothar; Fraxedas, Jordi; Zollner, Stefan; Riley, John D.; Leckey, Robert C. G.

    1994-09-01

    Angle-resolved constant-initial-state spectroscopy from the valence-band maximum (VBM) as the initial state was used to determine the conduction-band energies at the ? point up to 30 eV above the VBM for InSb. Structure in the spectra up to 20 eV could be assigned to particular interband transitions by comparison with empirical pseudopotential calculations. Autoionizing resonances due to surface core excitons have been observed. From their energies a surface-core-exciton binding energy of 0.5 eV for InSb has been determined. Both results are discussed in light of our previous work on the conduction-band states and surface core exditons of several III-V semiconductors.

  7. 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 ?g/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

  8. The metalorganic chemical vapor deposition of III-V nitrides for optoelectronic device applications

    NASA Astrophysics Data System (ADS)

    Grudowski, Paul Alexander

    Nitride-based light-emitting diodes (LEDs) and laser diodes are important for large-area LED displays, flat-panel displays, traffic signals, and optical data storage, due to their characteristic ultraviolet and visible light emission. However, much of the research and development addressing material related problems is recent. The room-temperature continuous wave (CW) operation of nitride-based laser diodes remains a major milestone because the material quality requirements for these devices are extremely high. This study investigates nitride material development by the metalorganic chemical vapor deposition (MOCVD) and characterization of GaN, AlGaN, and InGaN, and by qualifying these materials with fabricated devices. The ultimate goal was to develop a working laser diode. The nitride epitaxial films were characterized by 300K Hall effect, x-ray diffraction (XRD), photoluminescence (PL), cathodoluminescence (CL), secondary ion mass spectroscopy (SIMS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). GaN grown heteroepitaxially on (0001) sapphire substrates was first optimized. A low-temperature GaN nucleation layer was developed that gave subsequent high-temperature GaN layers with low background carrier concentrations (n < 1×10sp{17}\\ cmsp{-3}). Intentional p-type hole concentrations up to 2× 10sp{18} cmsp{-3} and n-type electron concentrations up to 1× 10sp{19} cmsp{-3} were achieved at 300K with magnesium and silicon, respectively. The ternary alloy Insb{x}Gasb{1-x}N was grown with indium compositions up to x = 0.25. These films exhibited strong and narrow 300K PL bandedge peaks. Multiple-quantum-well structures with Insb{0.13}Gasb{0.87}N wells and Insb{0.03}Gasb{0.97}N barriers were grown and gave enhanced PL intensity compared to single InGaN layers. Modulation-doped MQW's produced enhanced PL intensity compared to uniformly-doped MQW's. 300K photopumping experiments produced stimulated emission from a five-period MQW. Light-emitting device structures comprised of InGaN MQW active regions and p-type and n-type GaN contact layers and AlGaN confinement layers were grown and fabricated. LED's showed bright emission at a wavelength of 400 nm. While optically pumped lasers were demonstrated, no injection lasing action was achieved in these devices. GaN grown by selective area lateral epitaxial overgrowth (SALEO) has reduced dislocation defect density and, therefore, may prove to be a promising substrate for nearly defect-free device structures. Plan-view and cross-sectional CL was used to compare spatial inhomogeneities in the bandedge luminescence.

  9. GaN1-xBix: Extremely mismatched semiconductor alloys A. X. Levander,1,2

    E-print Network

    Wu, Junqiao

    that is lattice matched to GaAs.10­12 In addition, Bi in group III-V semiconductors has been used as a surfactantGaN1-xBix: Extremely mismatched semiconductor alloys A. X. Levander,1,2 K. M. Yu,1,a S. V. Novikov.1063/1.3499753 Semiconductor alloying is a common method for tailor- ing material properties for specific applications

  10. TOWARD ACHIEVING EFFICIENT III-V SPACE CELLS ON Ge/GeSi/Si WAFERS S.A. Ringel, R.M. Sieg and J.A. Carlin S. Ting, M. Currie, V. Yang, E.A. Fitzgerald

    E-print Network

    community for multi-functional device integration. For the specific case of space solar cellsTOWARD ACHIEVING EFFICIENT III-V SPACE CELLS ON Ge/GeSi/Si WAFERS S.A. Ringel, R.M. Sieg and J-V photovoltaic materials and Si wafers have long hampered the ability to integrate optimum III-V solar cells

  11. Giant and composition-dependent optical band gap bowing in dilute GaSb1-xNx alloys

    NASA Astrophysics Data System (ADS)

    Belabbes, A.; Ferhat, M.; Zaoui, A.

    2006-04-01

    Ab initio pseudopotential plane wave calculations and large 64-atom relaxed supercells are used to investigate the structural and electronic properties of GaNxSb1-x dilute alloys. While the band gaps of conventional III-V semiconductors have a simple and weak dependence on composition, this work illustrate a violation of this expected behavior. We show that the band gap decreases rapidly with increasing compositions of N and that GaNxSb1-x show an abnormal giant gap reduction. As a consequence, the optical band gap bowing is found to be giant and composition dependent as found for other mixed anion III-V-N systems.

  12. 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.

  13. Covalent Attachment to GaP(110) - Engineering the Chemical Functionalization of a III-V Semiconductor

    NASA Astrophysics Data System (ADS)

    Bradley, A. J.; Ugeda, M. M.; Liu, Wenjun; Yu, Min; Tilley, T. Don; Pérez, Rubén; Neaton, Jeffrey B.; Crommie, M. F.

    2014-03-01

    With its 2.3 eV bulk bandgap, relatively high conduction band edge, and low chemical reactivity, the (110) surface of GaP is an excellent candidate for many UV and visible light applications, such as photo-catalysis and light-induced chemical reduction. However, the reconstruction and resulting charge transfer of the surface makes it difficult to covalently attach the required molecules. Indeed, very little work has been done to understand either covalent functionalization or passivation of this surface. Here we report on a Staudinger-type, thermally-driven covalent attachment of perfluorophenyl azide (pfpa) to GaP(110). We have studied the adsorption of pfpa molecules by means of high-resolution scanning tunneling microscopy and spectroscopy in combination with first principles calculations. We show a progression from a physisorbed state at room temperature to a covalently attached state after exposure to slightly higher temperatures (~ 50°C). The developed approach is expected to be valid for various other functional groups attached to the azide, as well as other III-V semiconductors.

  14. Infrared surface plasmon resonances due to Er-V semimetallic nanoparticles in III-V semiconductor matrices

    NASA Astrophysics Data System (ADS)

    Hanson, M. P.; Gossard, A. C.; Brown, E. R.

    2007-08-01

    Absorption resonances attributed to surface plasmons are observed in various Er-V nanoparticle/III-V semiconductor superlattices grown by molecular beam epitaxy. ErAs particles in GaAs and GaAs0.5Sb0.5 as well as ErSb particles in GaSb and GaAs0.5Sb0.5 are investigated. Transmission measurements indicate resonant absorption peaks from 1.2to2.4?m depending on growth conditions for ErAs particles in GaAs. In the case of ErSb particles in GaSb these features are observed from about 2.4to4.5?m. For the ErAs or ErSb particles grown in GaAs0.5Sb0.5 the resonances were found to straddle the band gap of the semiconductor matrix around 1.5?m. Growth conditions are used to engineer the nanoparticles' shape and density in order to tune the wavelength and intensity of the resonance. The asymmetry of the ErSb particles, which preferentially elongate along the [01¯1] direction, leads to a dependence of the resonance on polarization of the incident light. The absorption peak for light polarized parallel to the long axis of the particles is found to occur at longer wavelengths than those for that for light polarized perpendicular to the long axis of the particles.

  15. Proteomic and metabolomic biomarkers for III-V semiconductors: And prospects for application to nano-materials

    SciTech Connect

    Fowler, Bruce A. [Program in Toxicology, University of Maryland, Baltimore, Maryland (United States); ATSDR, Atlanta, Georgia (United States)], E-mail: bxf9@cdc.gov; Conner, Elizabeth A. [Program in Toxicology, University of Maryland, Baltimore, Maryland (United States); NCI, Bethesda, Maryland (United States); Yamauchi, Hiroshi [Program in Toxicology, University of Maryland, Baltimore, Maryland (United States); Kitasato University (Japan)

    2008-11-15

    There has been an increased appreciation over the last 20 years that chemical agents at very low dose levels can produce biological responses in protein expression patterns (proteomic responses) or alterations in sensitive metabolic pathways (metabolomic responses). Marked improvements in analytical methodologies, such as 2-D gel electrophoresis, matrix-assisted laser desorption-time of flight (MALDI-TOF) and surface enhanced laser desorption-time of flight (SELDI-TOF) technologies are capable of identifying specific protein patterns related to exposure to chemicals either alone or as mixtures. The detection and interpretation of early cellular responses to chemical agents have also made great advances through correlative ultrastructural morphometric and biochemical studies. Similarly, advances in analytical technologies such as HPLC, proton NMR, MALDI-TOF, and SELDI-TOF have permitted early detection of changes in a number of essential metabolic pathways following chemical exposures by measurement of alterations in metabolic products from those pathways. Data from these approaches are increasingly regarded as potentially useful biomarkers of chemical exposure and early cellular responses. Validation and establishment of linkages to biological outcomes are needed in order for biomarkers of effect to be established. This short review will cover a number of the above techniques and report data from chemical exposures to two binary III-V semiconductor compounds to illustrate gender differences in proteomic responses. In addition, the use of these methodologies in relation to rapid safety evaluations of nanotechnology products will be discussed. (Supported in part by NIH R01-ES4879)

  16. Ab initio calculation of natural band offsets of all group IV, II-VI and III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Wei, Su-Huai; Walsh, Aron; Li, Yong-Hua; Gong, Xingao

    2010-03-01

    The natural band offset between semiconductors is one of the most fundamental properties in materials physics. It is a necessary quantity to assess charge transport and quantum confinement, and is of particular relevance to the design of optoelectronic devices which feature an interface between two or more materials. However, in the past, the natural band offset calculations were based on the assumption that certain reference levels (core levels, average Coulomb potentials, etc.) have zero absolute deformation potential, and thus align between the bulk and heterostructures. In this study [1], using an all-electron band structure approach, we have systematically calculated the natural band offsets between all group IV, III-V and II-VI semiconductor compounds, taking into account the deformation potential of the core states. This revised approach removes assumptions regarding the deformation potential of the reference levels, and offers a more reliable prediction of the `natural' unstrained offsets. Comparison is made to experimental work, where a noticeable improvement is found compared to previous methodologies. [1] Y.-H. Li et al., Appl. Phys. Lett. 94, 212109 (2009).

  17. Application of analytical k.p model with envelope function approximation to intersubband transitions in n-type III-V semiconductor Gamma quantum wells

    Microsoft Academic Search

    C. W. Cheah; L. S. Tan; G. Karunasiri

    2002-01-01

    A 14-band k.p model combined with an envelope function approximation has been developed for the analysis of III-V semiconductor quantum wells by including the six Gamma7, Gamma8 conduction bands nonperturbatively. With appropriate approximations, the envelope functions associated with the Gamma7, Gamma8 bands can be expressed in terms of the two Gamma6 conduction band envelope functions, which are the most important

  18. Application of analytical k.p model with envelope function approximation to intersubband transitions in n-type III–V semiconductor ? quantum wells

    Microsoft Academic Search

    C. W. Cheah; L. S. Tan; G. Karunasiri

    2002-01-01

    A 14-band k.p model combined with an envelope function approximation has been developed for the analysis of III–V semiconductor quantum wells by including the six ?7,?8 conduction bands nonperturbatively. With appropriate approximations, the envelope functions associated with the ?7,?8 bands can be expressed in terms of the two ?6 conduction band envelope functions, which are the most important components in

  19. Narrow-linewidth short-pulse III-V-on-silicon mode-locked lasers based on a linear and ring cavity geometry.

    PubMed

    Keyvaninia, S; Uvin, S; Tassaert, M; Fu, X; Latkowski, S; Mariën, J; Thomassen, L; Lelarge, F; Duan, G; Verheyen, P; Lepage, G; Van Campenhout, J; Bente, E; Roelkens, G

    2015-02-01

    Picosecond-pulse III-V-on-silicon mode-locked lasers based on linear and ring extended cavity geometries are presented. In passive mode-locked operation a 12 kHz -3dB linewidth of the fundamental RF tone at 4.7 GHz is obtained for the linear cavity geometry and 16 kHz for the ring cavity geometry. Stabilization of the repetition rate of these devices using hybrid mode-locking is also demonstrated. PMID:25836180

  20. Si(100) versus Ge(100): Watching the interface formation for the growth of III-V-based solar cells on abundant substrates

    Microsoft Academic Search

    S. Bruckner; O. Supplie; E. Barrigon; P. Kleinschmidt; A. Dobrich; I. Rey-Stolle; C. Algora; H. Doscher; T. Hannappel

    2011-01-01

    We investigated the atomic surface properties of differently prepared silicon and germanium (100) surfaces during metal-organic vapour phase epitaxy\\/chemical vapour deposition (MOVPE\\/MOCVD), in particular the impact of the MOVPE ambient, and applied reflectance anisotropy\\/difference spectroscopy (RAS\\/RDS) in our MOVPE reactor to in-situ watch and control the preparation on the atomic length scale for subsequent III-V-nucleation. The technological interest in the

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

    Microsoft Academic Search

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

    1997-01-01

    Besides the standard group V precursors AsH3 and PH3, 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

  2. Ab initio all-electron calculation of absolute volume deformation potentials of IV-IV, III-V, and II-VI semiconductors: The chemical trends

    Microsoft Academic Search

    Yong-Hua Li; X. G. Gong; Su-Huai Wei

    2006-01-01

    We calculate systematically the absolute volume deformation potential (AVDP) of the Gamma8v valence band maximum (VBM) and the Gamma6c conduction band minimum (CBM) states for all group IV, III-V, and II-VI semiconductors. Unlike previous calculations that involve various assumptions, the AVDPs are calculated using a recently developed approach that is independent of the selection of the reference energy levels. We

  3. A simple molecular-orbital theory of the nonlinear optical properties of group III-V and II-VI compounds

    Microsoft Academic Search

    CHUNG L. TANG

    1973-01-01

    The second-order nonlinear optical susceptibility in the low-frequency limit for Group III-V and II-VI semiconductors can be understood in terms of a very simple and yet surprisingly accurate molecular-orbital model of the tetrahedral bonds of the crystal. The physical origin of the nonlinearity is the field-dependence in the ionicity of the bond due to the transfer of valence charge from

  4. 230A problem: 1. III-V compound semiconductor GaAs has two families of cleavage planes (110) and (10). You

    E-print Network

    California at San Diego, University of

    230A problem: 1. III-V compound semiconductor GaAs has two families of cleavage planes (110 semiconductor lasers are fabricated (i.e. using the cleaved planes as reflecting mirrors). For a (211) GaAs structure of GaAs and InP? d. The lattice constant for GaAs is 5.65 . Find the interplane distances for (111

  5. Modeling of the degradation of III–V triple-junction cells due to particle irradiation on the basis of component cells

    Microsoft Academic Search

    C. Baur; A. W. Bett

    2010-01-01

    The paper reports about the possibility of predicting the degradation of III-V multi-junction solar cells due to particle irradiation in space solely based on the radiation response of the respective sub cells. State-of-the art triple-junction solar cells of the 3G28 class manufactured by AZUR Space GmbH are used as an example to demonstrate how to model the degradation behavior of

  6. Application of real-time low-energy ion scattering spectroscopy to heterointerface formation processes of molecular beam epitaxially grown III-V compound semiconductors

    Microsoft Academic Search

    M. Tamura; T. Saitoh; N. Sugiyama; A. Hashimoto; S. Ohkouchi; N. Ikoma; Y. Morishita

    1994-01-01

    Coaxial impact-collision ion scattering spectroscopy (CAICISS) has been applied for the in situ analysis of heterointerface formation processes and related phenomena of III-V compound semiconductors in a CAICISS\\/molecular beam epitaxy (MBE) system where CAICISS was directly combined with an MBE chamber. We first demonstrate that CAICISS is useful for studying surface step structures by taking vicinal GaAs (100) surfaces as

  7. Fabrication and Characterization of III-V Tunnel Field-Effect Transistors for Low Voltage Logic Applications

    NASA Astrophysics Data System (ADS)

    Romanczyk, Brian R.

    With voltage scaling to reduce power consumption in scaled transistors the subthreshold swing is becoming a critical factor influencing the minimum voltage margin between the transistor on and off-states. Conventional metal-oxide-semiconductor field-effect transistors (MOSFETs) are fundamentally limited to a 60 mV/dec swing due to the thermionic emission current transport mechanism at room temperature. Tunnel field-effect transistors (TFETs) utilize band-to-band tunneling as the current transport mechanism resulting in the potential for sub-60 mV/dec subthreshold swings and have been identified as a possible replacement to the MOSFET for low-voltage logic applications. The TFET operates as a gated p-i-n diode under reverse bias where the gate electrode is placed over the intrinsic channel allowing for modulation of the tunnel barrier thickness. When the barrier is sufficiently thin the tunneling probability increases enough to allow for significant number of electrons to tunnel from the source into the channel. To date, experimental TFET reports using III-V semiconductors have failed to produce devices that combine a steep subthreshold swing with a large enough drive current to compete with scaled CMOS. This study developed the foundations for TFET fabrication by improving an established Esaki tunnel diode process flow and extending it to include the addition of a gate electrode to form a TFET. The gating process was developed using an In0.53Ga 0.57As TFET which demonstrated a minimum subthreshold slope of 100 mV/dec. To address the issue of TFET drive current an InAs/GaSb heterojunction TFET structure was investigated taking advantage of the smaller tunnel barrier height.

  8. Fabrication and Characterization of Optoelectronics Devices Based on III-V Materials for Infrared Applications by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Torfi, Amin

    Optoelectronic devices based on III-V materials operating in infrared wavelength range have been attracting intensive research effort due to their applications in optical communication, remote sensing, spectroscopy, and environmental monitoring. The novel semiconductor lasers and photodetectors structures and materials investigated in this thesis cover the spectral range from 1.3µm to 12µm. This spectral region includes near-infrared (NIR), mid-infrared (MIR) and long wavelength infrared. This thesis demonstrated infrared optoelectronic devices, based on III-V compound semiconductors grown by Molecular Beam Epitaxy (MBE), utilizing various combinations of novel III-V materials, device structures and substrate orientations. This thesis will be presented in two parts; the first part focuses on two types of photodetectors; type-II InAs/GaSb superlattice IR detector and AlGaAsSb/InGaAsSb mid-infrared heterojunction p-i-n photodetector. The second part of this thesis focuses on the three types of quantum well (QW) lasers; phosphor-free1.3µm InAlGaAs strain-compensated multiple-quantum-well (SCMQW) lasers on InP (100), InGaAsNSb/GaAs quantum wells (QWs) grown on GaAs (411)A substrates and mid-infrared InGaAsSb lasers with digitally grown tensile-strained AlGaAsSb barriers. Type-II InAs/GaSb superlattice IR detectors with various spectral ranges were grown by MBE. Two superlattice structures with 15 monolayers (ML) of InAs/12ML GaSb and 17ML InAs/7ML GaSb are discussed. Based on X-ray diffraction (XRD) measurements both InAs/GaSb superlattices exhibit excellent material qualities with the full width at half maximum (FWHM) of the 0th-order peak about 20arcsec, which is among the narrowest ever reported. The 50% cutoff wavelengths at 80K of the two photodiodes with 15ML InAs/12ML GaSb and 17ML InAs/7ML GaSb superlattices are measured to be 10.2µm and 6.6µm, respectively. Mid-infrared heterojunction p-i-n photodetector, AlGaAsSb/InGaAsSb lattice-matched to GaSb grown by solid source molecular beam epitaxy using As and Sb valved crackers greatly facilitated the lattice-matching of the quaternary InGaAsSb absorbing layer to the GaSb substrates, as characterized by X-ray diffraction. The resulting device exhibited low dark current and a breakdown voltage of 32V at room temperature. A record Johnson-noise-limited detectivity of 9.0 × 1010 cm Hz½/W was achieved at 290K. The 50% cutoff wavelength of the device was 2.57 µm. Thus, our result has clearly demonstrated the potential of very high-performance lattice-matched InGaAsSb p-i-n photodetectors for mid-infrared wavelengths. For phosphor-free1.3 µm InAlGaAs multiple-quantum-well (MQW) lasers, the substrate temperature has been found to be a critical growth parameter for lattice-matched InAl(Ga)As layers in the laser structures. As shown by X-ray diffraction measurements, in the temperature range of 485-520° C, spontaneously ordered superlattices (SLs) with periods around 7-10 nm were formed in the bulk InAl(Ga)As layers. Based on photoluminescence (PL) measurements, a large band gap reduction of 300 meV and a broadened PL peak were observed for the In0.52 Al0.48As layers with SL, as compared to those without SL. The undesirable, spontaneously-ordered SL can be avoided by using MBE growth temperatures higher than 530 °C. This results in a high laser performance. Threshold-current density as low as 690 A/cm2 and T0 as high as 80 K were achieved for InAlGaAs laser bars emitting at 1310 nm. InGaAsNSb/GaAs QWs on GaAs (411)A exhibited remarkably enhanced photoluminescence efficiency compared with the same structures on conventional GaAs (100) substrates. It was further observed that the optimum growth temperature for (411)A was 30 °C higher than that for (100). To explain this phenomenon, a model based on the self-assembling of local rough surface domains into a unique global smooth surface at the lowest energy state of the system is proposed. Lastly, the digital-growth approach for tensile-strained AlGaAsSb barriers improved the reliability and controllability of MBE growth fo

  9. 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.

  10. Photoluminescence and secondary ion mass spectrometry investigation of unintentional doping in epitaxial germanium thin films grown on III-V compound by metal-organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Bai, Yu; Bulsara, Mayank T.; Fitzgerald, Eugene A.

    2012-01-01

    High quality epitaxial germanium (Ge) thin films grown on lattice matched and mismatched III-V compound may lead to development of new electronic and optoelectronic devices. Understanding the doping and electronic properties of these Ge thin films is the first step in this development. In this paper, we report on high-quality epitaxial Ge thin films grown on GaAs and AlAs by metal-organic chemical vapor deposition. Cross-sectional transmission electron microscopy and atomic force microscopy reveal the high structural quality of the Ge thin films. Using photoluminescence, secondary ion mass spectrometry, and spreading resistance analysis, we investigated the unintentional doping characteristics of the fabricated Ge-on-III-V thin films. We found that arsenic (n-type doping) concentration is determined by the background partial pressure of volatile As-species (e.g., As2 and As4), which incorporate into the Ge thin films via gas phase transport during the growth. Group III element (p-type doping) incorporation in the Ge thin films occurs during the growth through a surface exchange process. There exists a trade-off between Ge film structural quality and group III element "auto-doping." III-V compound surfaces that are group III element-rich facilitate the initiation of Ge thin films with high crystalline quality and low surface roughness. However, the group-III-rich surfaces also result in high group III element (p-type doping) concentrations in the Ge thin films.

  11. Optical properties of zinc-blende semiconductor alloys: Effects of epitaxial strain and atomic ordering

    Microsoft Academic Search

    Su-Huai Wei; Alex Zunger

    1994-01-01

    Spontaneous ordering of III-V alloys is known to cause a band-gap reduction ||DeltaEg|| and a splitting DeltaE12 of the valence-band maximum. Strain also leads to a valence-band splitting and, depending on the sign of the strain ?, to an increase (for ?0) in the band gap. We present a general theory explaining how the strain produced by lattice mismatch with

  12. 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° and 6° misorientation, respectively. The second focus of this study was on the OMVPE growth of InAs quantum dots in a large-area commercial reactor. Quantum dot growth parameters require careful balancing in the large-scale reactor due to different thermodynamic and flow profiles compared with smaller- area reactors. The goal of the work was to control the growth process in order to produce high densities of uniform quantum dots for inclusion in double and triple junction III - V material solar cells. Initial growth proved unsuccessful due to lack of familiarity with the process but through balancing of injector flows of alkyl gasses, coherent and optically active quantum dots were able to first be formed at low densities (0.5 - 0.7 x 1010 cm-2). Further optimization included increased quantum dot growth times leading to number densities in the (2.1-2.7x10 10cm-2 with improved optical performance as measured by photoluminescence (PL) spectroscopy. Finally, an investigation of GaAs spacer layer thickness for improved optical coupling was performed, indicating that a combined low temperature and high temperature GaAs thickness of 9.3nm led to strong PL intensity indicating good optical coupling of QD layers. Ge/(In)GaAs double junction solar cells were grown and fabricated with and without quantum dots in the (In)GaAs cell to investigate the effect of quantum dot inclusion on device performance. AM 0 measurements showed an average increase of 1.0mA/cm 2 in short-circuit current for these devices. Integrated spectral response measurements revealed a contribution to short-circuit current of 0.02mA/cm2/QDlayer which is consistent with reports seen in literature. The current improvement for the double junction solar cells motivated the investigation of quantum dot inclusion in the (In)GaAs junction of a Ge/(In)GaAs/InGaP triple junction solar cell. AM0 measurements on these cells did not reveal any increase in current for quantum dot enhanced devices over a baseline device. Integrated spectral response for each junction revealed an increase of 0.3mA/cm 2 in cur

  13. Self-Interaction Corrections to the Electronic Structure of II-VI and III-V Nitride Semiconductors

    Microsoft Academic Search

    J. Pollmann

    1998-01-01

    II-VI and group-III nitride semiconductors have paramount technological potential for applications in micro- and optoelectronics. A most accurate description of their bulk electronic structure as a basis for studying defect properties, band-edge properties in respective ternary or quaternary alloys and electronic properties of their surfaces and interfaces is of major importance, therefore. Standard LDA band-structure calculations for these wide-band-gap compounds

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

    DOEpatents

    Norman, Andrew G. (Evergreen, CO); Olson, Jerry M. (Lakewood, CO)

    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.

  15. GaP heteroepitaxy on Si(001): Correlation of Si-surface structure, GaP growth conditions, and Si-III/V interface structure

    NASA Astrophysics Data System (ADS)

    Beyer, A.; Ohlmann, J.; Liebich, S.; Heim, H.; Witte, G.; Stolz, W.; Volz, K.

    2012-04-01

    GaP-layers on Si(001) can serve as pseudo-substrates for a variety of novel optoelectronic devices. The quality of the GaP nucleation layer is a crucial parameter for the performance of such devices. Especially, anti-phase domains (APDs) evolving at mono-atomic steps on the Si-surface can affect the quality of a layer adversely. The size, shape, and possible charge of the APDs and their boundaries depend on the polarity of the surrounding crystal. The observed polarity of the GaP is caused by the A-type double step configuration of the Si-surface reconstruction prior to GaP growth and the prevalent binding of Ga to Si under optimized growth conditions. The polarity of the GaP-layer and hence the atomic configuration at the Si-III/V interface can be changed by altering the growth conditions. With this knowledge, defect-free GaP/Si(001) templates for III/V device integration on Si-substrates can be grown.

  16. Nanoscale opening fabrication on Si (111) surface from SiO2 barrier for vertical growth of III-V nanowire arrays

    NASA Astrophysics Data System (ADS)

    Shi, Tuanwei; Wang, Xiaoye; Wang, Baojun; Wang, Wei; Yang, Xiaoguang; Yang, Wenyuan; Chen, Qing; Xu, Hongqi; Xu, Shengyong; Yang, Tao

    2015-07-01

    We reported here a selectively additive process to fabricate nanoscale openings of an Si (111) surface from an SiO2 barrier layer. Such nanoscale openings are made for the growth of vertical III–V nanowires. The Si (111) surface protected by a patterned SiNx layer was thermally oxidized, which resulted in a selectively added SiO2 barrier layer. After removing the SiNx, nanoscale openings of the Si (111) surface were exposed for the nanowire growth. Arrays with patterned nanoholes of varied diameters from 60 nm to 334 nm have been used for position-controlled catalyst-free growth of vertical InAs nanowire arrays by metal-organic chemical vapor deposition. Correlations between the nanohole diameter and the diameter, length and growth yield of as-fabricated nanowire arrays have been investigated, showing a repeatable stability. This technique offers an alternative approach for the fabrication of novel III–V nanowire devices using vertical array configuration. A lateral thermal oxidation effect led to a smaller size of the Si opening than that of the SiNx protection nanoislands; therefore, the technique also offers a controllable way to produce nanoholes with an ultra-small diameter.

  17. Stability of Metal Oxide/Ge and Metal Oxide/III-V Interfaces and Implications for Low Defect Density MOS Devices

    NASA Astrophysics Data System (ADS)

    McIntyre, Paul

    2008-03-01

    The need to achieve high performance in MOS transistors as they scale to their ultimate size limits prompts interest in channel materials, such as Ge and III-V compound semiconductors, which exhibit larger intrinsic carrier mobilities than Si. Given the need to reduce gate leakage current density while maintaining electrostatic control of the devices, it is necessary to deposit high-k gate dielectrics onto these novel channel materials. Unlike silicon, high mobility channel materials do not form a highly-stable and stoichiometric native oxide; therefore, control of the state of oxidation at the metal oxide dielectric/channel interface during and after gate dielectric deposition is essential. This presentation will summarize findings reported to date on 1) chemical stability of Ge and III-V surfaces in the presence of oxygen and 2) oxide/channel defect formation and passivation. New results on pre-high-k chemical surface preparation, structural modification during metal oxide deposition and the resulting effects on MOS capacitor and transistor characteristics will also be presented, with emphasis on Al2O3 and HfO2 gate insulators grown by atomic layer deposition onto Ge and InGaAs channels. In situ and ex situ monitoring of chemical bonding at the gate insulator/channel interface by photoelectron spectroscopy will be correlated with the Dit, fixed charge and charge trapping behavior of MOS devices.

  18. Nanoscale opening fabrication on Si (111) surface from SiO2 barrier for vertical growth of III-V nanowire arrays.

    PubMed

    Shi, Tuanwei; Wang, Xiaoye; Wang, Baojun; Wang, Wei; Yang, Xiaoguang; Yang, Wenyuan; Chen, Qing; Xu, Hongqi; Xu, Shengyong; Yang, Tao

    2015-07-01

    We reported here a selectively additive process to fabricate nanoscale openings of an Si (111) surface from an SiO2 barrier layer. Such nanoscale openings are made for the growth of vertical III-V nanowires. The Si (111) surface protected by a patterned SiNx layer was thermally oxidized, which resulted in a selectively added SiO2 barrier layer. After removing the SiNx, nanoscale openings of the Si (111) surface were exposed for the nanowire growth. Arrays with patterned nanoholes of varied diameters from 60 nm to 334 nm have been used for position-controlled catalyst-free growth of vertical InAs nanowire arrays by metal-organic chemical vapor deposition. Correlations between the nanohole diameter and the diameter, length and growth yield of as-fabricated nanowire arrays have been investigated, showing a repeatable stability. This technique offers an alternative approach for the fabrication of novel III-V nanowire devices using vertical array configuration. A lateral thermal oxidation effect led to a smaller size of the Si opening than that of the SiNx protection nanoislands; therefore, the technique also offers a controllable way to produce nanoholes with an ultra-small diameter. PMID:26062784

  19. Quasiparticle self-consistent GW theory of III-V nitride semiconductors: Bands, gap bowing, and effective masses

    NASA Astrophysics Data System (ADS)

    Svane, A.; Christensen, N. E.; Gorczyca, I.; van Schilfgaarde, M.; Chantis, A. N.; Kotani, T.

    2010-09-01

    The electronic band structures of InN, GaN, and a hypothetical ordered InGaN2 compound, all in the wurtzite crystal structure, are calculated using the quasiparticle self-consistent GW approximation. This approach leads to band gaps which are significantly improved compared to gaps calculated on the basis of the local approximation to density functional theory, although generally overestimated by 0.2-0.3 eV in comparison with experimental gap values. Details of the electronic energies and the effective masses including their pressure dependence are compared with available experimental information. The band gap of InGaN2 is considerably smaller than what would be expected by linear interpolation implying a significant band gap bowing in InGaN alloys.

  20. Dependence of doubly curved regions on drying method in the fabrication of long-side rolled-up III-V microtubes

    NASA Astrophysics Data System (ADS)

    Li, Bochang; Wang, Qi; Wang, Eryang; Jia, Zhigang; Yan, Yingce; Bian, Zhiqiang; Ren, Xiaomin; Cai, Shiwei; Huang, Yongqing

    2013-07-01

    Through improving fabrication process, short-side rolling phenomenon has been eliminated, and well-aligned long-side rolled-up III-V microtube arrays have been achieved. Finite element method (FEM) has been exploited to simulate the evolution of strain energy in the entire self-rolling process, showing that the difference of strain-released regions is the major factor that determines the rolling direction. Meanwhile, the doubly curved regions have been observed around the openings of air-dried microtubes but do not exist on the microtubes dried in critical point dryer, which demonstrates this structural deformation results not from the release of residual strain energy but from the surface tension.

  1. Origin of nonlinear piezoelectricity in III-V semiconductors: Internal strain and bond ionicity from hybrid-functional density functional theory

    NASA Astrophysics Data System (ADS)

    Caro, Miguel A.; Schulz, Stefan; O'Reilly, Eoin P.

    2015-02-01

    We derive first- and second-order piezoelectric coefficients for the zinc-blende III-V semiconductors {Al ,Ga ,In }-{N ,P ,As ,Sb } . The results are obtained within the Heyd-Scuseria-Ernzerhof hybrid-functional approach in the framework of density functional theory and the Berry-phase theory of electric polarization. To achieve a meaningful interpretation of the results, we build an intuitive phenomenological model based on the description of internal strain and the dynamics of the electronic charge centers. We discuss in detail first- and second-order internal strain effects, together with strain-induced changes in ionicity. This analysis reveals that the relatively large importance in the III-Vs of nonlinear piezoelectric effects compared to the linear ones arises because of a delicate balance between the ionic polarization contribution due to internal strain relaxation effects, and the contribution due to the electronic charge redistribution induced by macroscopic and internal strain.

  2. 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. [Purdue Univ., Lafayette, IN (United States)

    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.

  3. 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. [Purdue Univ., Lafayette, IN (United States)

    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.

  4. 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.

  5. Band gap bowing in large size-mismatched II-VI alloys

    NASA Astrophysics Data System (ADS)

    Wei, Su-Huai; Moon, Chang-Youn; Zhu, Y. Z.; Chen, G. D.

    2007-03-01

    Band gap bowing coefficients in large size-mismatched II-VI alloys M^IIX^VI1-xOx with M^II=Zn and Cd, and X^VI=S, Se, and Te in the zinc-blend structure are calculated using first-principles methods. We show that in these systems, the bowing coefficients are large and composition-dependent. The bowing coefficients increase as the size and chemical mismatch between the constituents increase. The bowing coefficients for the Zn alloys are larger than the corresponding Cd alloys, but smaller than the corresponding III-V alloys. We show that these results can be explained by the size and atomic eigenvalue differences between the constituents and the resulting band offsets and isovalent defect levels in these systems. Our results are compared with recent experimental data.

  6. 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 solaires multi-jonction (MJSC), revêtement antireflet (ARC), passivation des semiconducteurs III-V, nitrure de silicium (Si?Ny), PECVD.

  7. Optical phonon modes of III-V nanoparticles and indium phosphide/II-VI core-shell nanoparticles: A Raman and infrared study

    NASA Astrophysics Data System (ADS)

    Manciu, Felicia Speranta

    The prospects for realizing efficient nanoparticle light emitters in the visible/near IR for communications and bio-medical applications have benefited from progress in chemical fabrication of nanoparticles. III-V semiconductor nanopaticles such as GaP and InP are promising materials for the development of "blue" and "green" emitters, respectively, due to their large effective bandgaps. Enhanced emission efficiency has been achieved for core-shell nanoparticles, since inorganic shell materials increase electronic tunability and may decrease surface defects that often occur for nanoparticles capped with organic molecules. Also, the emission wavelength of InP nanoparticle cores can be tuned from green to red by changing the shell material in InP/II-VI core-shell nanoparticles. Investigations of phonon modes in nanocrystals are of both fundamental and applied interest. In the former case the optical phonon modes, such as surface/interface modes, are dependent on the nanoparticle dimensions, and also can provide information about dynamical properties of the nanoparticles and test the validity of various theoretical approaches. In the latter case the vibronic properties of nanoparticle emitters are controlled by confined phonons and modifications of the electron-phonon interaction by the confinement. Thus, the objective of the present thesis is the detailed study of the phonon modes of III-V nanoparticles (GaP and InP) and InP/II-VI core-shell nanoparticles by IR absorption and Raman scattering spectroscopies, and an elucidation of their complex vibrational properties. With the exception of three samples (two GaP and one InP), all samples were synthesized by a novel colloidal chemistry method, which does not requires added surfactant, but rather treatment of the corresponding precursors in octadecene noncoordinative solvent. Sample quality was characterized by ED, TEM and X-ray diffraction. Based on a comparison with a dielectric continuum model, the observed features in the IR and Raman results are assigned to the surface optical (SO) modes of the corresponding nanoparticles (InP and GaP), and to SO/interface modes for InP/II-VI core-shell nanoparticles. For the latter systems, an evaluation of the ratio of the shell material thickness to the core radius is achieved. Reasonable agreement is obtained between the Raman and FIR results, as well as with the calculations. (Abstract shortened by UMI.)

  8. Atomic chains of group-IV elements and III-V and II-VI binary compounds studied by a first-principles pseudopotential method

    NASA Astrophysics Data System (ADS)

    Senger, R. T.; Tongay, S.; Durgun, E.; Ciraci, S.

    2005-08-01

    Using the first-principles plane wave pseudopotential method we have studied structural, electronic, and transport properties of atomic chains of group-IV elements and group III-V and group II-VI binary compounds. Several materials which are insulating or semiconducting in bulk are found to be metallic in nanowire structures. Our calculations reveal that monatomic chains of Si, Ge, and Sn elements, and of binary compounds such as InP, GaAs, and AlSb, are stable and metallic. On the other hand, compound wires of BN, SiC, GaN, ZnSe, and several others have semiconducting or insulating properties. Ideal mechanical strength calculations show that some of these atomic chains can sustain strains of up to ?=0.3 . We have presented ab initio electron transport calculations for Si and AlP linear chain segments in between Al electrodes. Conductance of Si monatomic chains displays some nontrivial features as the number of atoms in the chain is varied or as the chain is strained. In addition to single atomic chain structures, junctions and grid structures of Si are investigated.

  9. 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 (?) of ~16.47% was obtained, indicating an increased efficiency by 3.47% compared to the bare solar cell (i.e., ?~13%). PMID:24922242

  10. 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 (?) of ~16.47% was obtained, indicating an increased efficiency by 3.47% compared to the bare solar cell (i.e., ?~13%). PMID:24800289

  11. 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 ?m and 3 ?m 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.

  12. Epitaxial lift-off of II-VI semiconductors from III-V substrates using a MgS release layer

    NASA Astrophysics Data System (ADS)

    Rajan, Akhil; Davidson, Ian A.; Moug, Richard T.; Prior, Kevin A.

    2013-12-01

    Epitaxial lift-off (ELO) is a post-growth process that allows an epitaxial layer to be removed from its original substrate and transferred to a new one. ELO has previously been successfully demonstrated for III-V materials and also ZnSe based II-VI semiconductors using a MgS sacrificial layer. Following the recent successful growth of epitaxial MgS layers on GaP and InP substrates, in this paper we compare ELO of II-VI epilayers grown on GaP, GaAs, and InP substrates using MgS sacrificial layers in the range of 7-15 nm thick. Good quality lifted layers are obtained rapidly from InP and GaAs substrates. For GaP substrates, ELO is much slower and good quality lifts have only been achieved with ZnSe epilayers. Photoluminescence spectra obtained from epitaxial layers before and after ELO show changes in peak positions, which are compatible with changes of strain in the layer. The layers produced by ELO are flat and free of cracks, suggesting that this is an efficient and convenient method for the transfer of II-VI epitaxial layers to other substrates.

  13. A mixed-valence polyoxovanadate(III,IV) cluster with a calixarene cap exhibiting ferromagnetic V(III)-V(IV) interactions.

    PubMed

    Aronica, Christophe; Chastanet, Guillaume; Zueva, Ekaterina; Borshch, Serguei A; Clemente-Juan, Juan M; Luneau, Dominique

    2008-02-20

    A series of compounds (cat)[V6O6(OCH3)8(calix)(CH3OH)] was obtained under anaerobic conditions and solvothermal reaction of VOSO4 with p-tert-butylcalix[4]arene (calix) in methanol using different types of bases (Et4NOH, NH4OH, pyridine, Et3N). All compounds contain the same polyoxo(alkoxo)hexavanadate anion [V6O6(OCH3)8(calix)(CH3OH)]- (1) exhibiting a mixed valence {VIIIVIV5O19} core with the so-called Lindqvist structure coordinated to a calix[4]arene macrocycle and cocrystallizing with the conjugated acid of the base (cat = Et4N+, NH4(+), pyridinium, Et3NH+) involved in the synthesis process. The structures have been fully established from X-ray diffraction on single crystals and the mixed valence state has been confirmed by bond valence sum calculations. The magnetic behavior of all compounds are the same because of the polyalkoxohexavanadate anion [V6O6(OCH3)8(calix)(CH3OH)]- (1) and have been interpreted by DFT calculations. Thus the V(III)...V(IV) interactions are found to be weakly ferromagnetic (<5.5 cm(-1)) while the V(IV)...V(IV) are antiferromagnetic (-17.6; -67.6 cm(-1)). The set of the coupling exchange parameters allows a good agreement with the magnetic experimental data. PMID:18215045

  14. Synthesis of III-V compound semiconductor materials: an assessment of research and development activities in the United States and Japan

    NASA Astrophysics Data System (ADS)

    Collins, Douglas M.

    1986-04-01

    A comparative assessment of U.S. and Japanese research and development activities in the field of III-V compound semiconductor materials is presented. Work on both epitaxial materials (i.e., molecular beam epitaxy (MBE) and organometallic vapor phase epitaxy (OMVPE) of materials in the (Al, Ga)As and (In, Ga)(As,P) systems and bulk materials (i.e., liquid-encapsulated Czochralski (LEC) growth of GaAs) is described with an emphasis on high-speed and optoelectronic device and integrated circuit applications. The assessment is based primarily on widely available information including that which is disseminated in both English-language and Japanese-language journals and conferences. Key points which are addressed include (1) a comparison of U.S. and Japanese technical achievements, (2) the equity of technical exchanges between the U.S. and Japan, and (3) the relative effectiveness with which these technologies are commercialized in the U.S. and Japan.

  15. Band-gap bowing coefficients in large size-mismatched II-VI alloys: first-principles calculations

    NASA Astrophysics Data System (ADS)

    Moon, Chang-Youn; Wei, Su-Huai; Zhu, Y. Z.; Chen, G. D.

    2006-12-01

    Band-gap bowing coefficients in large size-mismatched II-VI alloys MIIX1-xVIOx with MII=Zn and Cd, and XVI=S , Se, and Te in the zinc-blende structure are calculated using first-principles methods. We show that in these systems, the bowing coefficients are large and composition dependent. The bowing coefficients increase as the size and chemical mismatch between the constituents increase. The bowing coefficients for the Zn alloys are larger than the corresponding Cd alloys, but smaller than the corresponding III-V alloys. We show that these results can be explained by the size and atomic eigenvalue differences between the constituents and the resulting band offsets and isovalent defect levels in these systems. Our results are compared with recent experimental data.

  16. 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. PMID:22109493

  17. Wide-Bandgap III–V nitride based avalanche transit-time diode in Terahertz regime: Studies on the effects of punch through on high frequency characteristics and series resistance of the device

    Microsoft Academic Search

    Moumita Mukherjee; Sitesh Kumar Roy

    2010-01-01

    Extensive simulation investigations on III–V nitride (Gallium Nitride, GaN) based Single Drift (p++ n n++) avalanche transit-time diode clearly establishes the potential of GaN material system in Terahertz region. Further, the effects of punch through on the Terahertz behavior of the GaN IMPATT (IMPact Avalanche Transit-Time diode) are studied for the first time, through a generalized simulation technique. The computed

  18. Solvothermal syntheses, crystal structures, and properties of new mercury(II)-thioantimonates(III) and a mixed-valent thioantimonate(III,V)

    NASA Astrophysics Data System (ADS)

    Tang, Weiwei; Tang, Chunying; Wang, Fang; Chen, Ruihong; Zhang, Yong; Jia, Dingxian

    2013-03-01

    New heterometallic thioantimonates(III) [Co(dien)2]HgSb2S5 (1), [Ni(dien)2]HgSb2S5 (2) and [H2dien]HgSb8S14 (3), and a mixed-valent thioantimonate(III,V) [Co(dien)2]2Sb4S9 (4) were solvothermally prepared in diethylenetriamine (dien) solvent from Co(Ni)-Hg-Sb-S, Hg-Sb-S and Co-Sb-S systems, respectively. In 1 and 2, the bimeric subunit Sb2S5 condenses with HgS4 tetrahedron via sharing common S atoms to form an one-dimensional [HgSb2S5]n2n- chain, in which a new ?3-1?2S1,S5:2?S2:3?S4 bridging mode of the Sb2S5 subunit is obtained. In 3, four SbS3 trigonal pyramids and a linear HgS2 unit condense via sharing S atoms to generate an one-dimensional double-lined [HgSb8S14] n2n- chain. In 4, three SbIIIS3 pyramids and a SbVS4 tetrahedron share common corners to form an one-dimensional mixed-valent [Sb4S9]n4n- anion. The syntheses of 1-4 demonstrated that the Hg2+ ion is easily incorporated into thioantimonate networks, and has a higher affinity to S than that of transition metals. 1-4 exhibit semiconducting properties with optical band gaps in 2.0-2.4 eV.

  19. Mechanical Alloying

    Microsoft Academic Search

    J. S. Benjamin

    1976-01-01

    A new technique of combining metals has been developed which overcomes many of the limitations of conventional alloying. Ball mills that generate higher energies than conventional ball mills are used to tumble a mixture of powders, such as WC and Co, in order to form a composite. Ni-base alloys can be dispersion-hardened in this way with an oxide such as

  20. 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.

  1. GaAsPN-based PIN solar cells MBE-grown on GaP substrates: toward the III-V/Si tandem solar cell

    NASA Astrophysics Data System (ADS)

    Da Silva, M.; Almosni, S.; Cornet, C.; Létoublon, A.; Levallois, C.; Rale, P.; Lombez, L.; Guillemoles, J.-F.; Durand, O.

    2015-03-01

    GaAsPN semiconductors are promising material for the elaboration of high efficiencies tandem solar cells on silicon substrates. GaAsPN diluted nitride alloy is studied as the top junction material due to its perfect lattice matching with the Si substrate and its ideal bandgap energy allowing a perfect current matching with the Si bottom cell. We review our recent progress in materials development of the GaAsPN alloy and our recent studies of some of the different building blocks toward the elaboration of a PIN solar cell. A lattice matched (with a GaP(001) substrate, as a first step toward the elaboration on a Si substrate) 1?m-thick GaAsPN alloy has been grown by MBE. After a post-growth annealing step, this alloy displays a strong absorption around 1.8-1.9 eV, and efficient photoluminescence at room temperature suitable for the elaboration of the targeted solar cell top junction. Early stage GaAsPN PIN solar cells prototypes have been grown on GaP (001) substrates, with 2 different absorber thicknesses (1?m and 0.3?m). The external quantum efficiencies and the I-V curves show that carriers have been extracted from the GaAsPN alloy absorbers, with an open-circuit voltage of 1.18 V, while displaying low short circuit currents meaning that the GaAsPN structural properties needs a further optimization. A better carrier extraction has been observed with the absorber displaying the smallest thickness, which is coherent with a low carriers diffusion length in our GaAsPN compound. Considering all the pathways for improvement, the efficiency obtained under AM1.5G is however promising.

  2. 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.

  3. The carrier contribution to the elastic constants in III–V, ternary and quaternary materials in the presence of light waves: Simplified theory, relative comparison and a suggestion for experimental determination

    Microsoft Academic Search

    K. P. Ghatak; S. Bhattacharya; S. Pahari; S. N. Mitra; P. K. Bose; D. De

    2009-01-01

    In this paper, we have studied the electronic contribution to the elastic constants for III–V, ternary and quaternary materials in the presence of light waves on the basis of newly formulated electron statistics. It has been found taking n-InAs, n-InSb, n-Hg1?xCdxTe and n-In1?xGaxAsyP1?y lattice matched to InP, as examples that the elastic constants increase with increasing electron concentration, intensity and

  4. Epitaxial growth in dislocation-free strained asymmetric alloy films

    SciTech Connect

    Desai, Rashmi C.; Kim, Ho Kwon; Chatterji, Apratim; Ngai, Darryl; Chen Si; Yang Nan [Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7 (Canada)

    2010-06-15

    Epitaxial growth in strained asymmetric, dislocation-free, coherent, alloy films is explored. Linear-stability analysis is used to theoretically analyze the coupled instability arising jointly from the substrate-film lattice mismatch (morphological instability) and the spinodal decomposition mechanism. Both the static and growing films are considered. Role of various parameters in determining stability regions for a coherent growing alloy film is investigated. In addition to the usual parameters: lattice mismatch {epsilon}, solute-expansion coefficient {eta}, growth velocity V, and growth temperature T, we consider the alloy asymmetry arising from its mean composition. The dependence of elastic moduli on composition fluctuations and the coupling between top surface and underlying bulk of the film also play important roles. The theory is applied to group III-V films such as GaAsN, InGaN, and InGaP and to group IV Si-Ge films at temperatures below the bare critical temperature T{sub c} for strain-free spinodal decomposition. The dependences of various material parameters on mean concentration and temperature lead to significant qualitative changes.

  5. VAl Alloy

    NASA Astrophysics Data System (ADS)

    Mikami, M.; Mizoshiri, M.; Ozaki, K.; Takazawa, H.; Yamamoto, A.; Terazawa, Y.; Takeuchi, T.

    2014-06-01

    Power generation performance of a thermoelectric module consisting of the Heusler Fe2VAl alloy was evaluated. For construction of the module, W-doped Fe2VAl alloys were prepared using powder metallurgy process. Power generation tests of the module consisting of 18 pairs of p- n junctions were conducted on a heat source of 373-673 K in vacuum. The reduction of thermal conductivity and improvement of thermoelectric figure of merit by W-doping enhanced the conversion efficiency and the output power. High output power density of 0.7 W/cm2 was obtained by virtue of the high thermoelectric power factor of the Heusler alloy. The module exhibited good durability, and the relatively high output power was maintained after temperature cycling test in air.

  6. Orthodontic silver brazing alloys.

    PubMed

    Brockhurst, P J; Pham, H L

    1989-10-01

    Orthodontic silver brazing alloys suffer from the presence of cadmium, excessive flow temperatures, and crevice corrosion on stainless steel. Seven alloys were examined. Two alloys contained cadmium. The lowest flow temperature observed was 629 degrees C for a cadmium alloy and 651 degrees C for two cadmium free alloys. Three alloys had corrosion resistance superior to the other solders. Addition of low melting temperature elements gallium and indium reduced flow temperature in some cases but produced brittleness in the brazing alloy. PMID:2576971

  7. 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. [EDTEK Inc. 7082 S. 220th Street Kent, Washington 98032 (United States); Morosini, M.B.; Patel, N.B. [Instituto de Fisica, UNICAMP, Campinas, Brasil (Brazil); Field, H. [NREL, Golden, Colorado (United States)

    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.}

  8. Distributed feedback GaSb based laser diodes with buried grating

    SciTech Connect

    Gaimard, Q.; Cerutti, L.; Teissier, R.; Vicet, A. [IES, UMR CNRS 5214, CC067, Université Montpellier 2, Place Eugene Bataillon, 34095 Montpellier Cedex 05 (France)

    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??m-wide laser ridges. Single frequency laser emission at a wavelength of 2.2??m 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.

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

    NASA Astrophysics Data System (ADS)

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

    1997-03-01

    In this work we report the characteristics of ternary, GaInSb (Eg=0.70 eV) and quarternary, GaInAsSb (Eg=0.5 eV) 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 0.8 A/cm2, while the corresponding values for the quarternary device are 0.25 V, 0.58 and 0.8 A/cm2, respectively. The peak internal quantum efficiency for the ternary is over 90% and that of the quarternary is above 75%. Process optimization should improve the performance charcateristics of the quarternary.

  10. Electroluminescence and phototrigger effect in single crystals of GaS{sub x}Se{sub 1-x} alloys

    SciTech Connect

    Kyazym-Zade, A. G., E-mail: bsu_aydin@yahoo.com; Salmanov, V. M.; Mokhtari, A. G.; Dadashova, V. V.; Agaeva, A. A. [Baku State University (Azerbaijan)

    2008-05-15

    The effects of switching and electroluminescence as well as the interrelation between these effects in single crystals of GaS{sub x}Se{sub 1-x} alloys are detected and studied. It is established that the threshold voltage for switching depends on temperature, resistivity, and composition of alloys, and also on the intensity and spectrum of photoactive light. As a result, a phototrigger effect is observed; this effect arises under irradiation with light from the fundamental-absorption region. Electroluminescence is observed in the subthreshold region of the current-voltage characteristic; the electroluminescence intensity decreases drastically to zero as the sample is switched from a high-resistivity state to a low-resistivity state. Experimental data indicating that the electroluminescence and the switching effect are based on the injection mechanism (as it takes place in other layered crystals of the III-V type) are reported.

  11. Quantitative evaluation of microtwins and antiphase defects in GaP/Si nanolayers for a III–V photonics platform on silicon using a laboratory X-ray diffraction setup1

    PubMed Central

    Ping Wang, Yan; Letoublon, Antoine; Nguyen Thanh, Tra; Bahri, Mounib; Largeau, Ludovic; Patriarche, Gilles; Cornet, Charles; Bertru, Nicolas; Le Corre, Alain; Durand, Olivier

    2015-01-01

    This study is carried out in the context of III–V semiconductor monolithic integration on silicon for optoelectronic device applications. X-ray diffraction is combined with atomic force microscopy and scanning transmission electron microscopy for structural characterization of GaP nanolayers grown on Si. GaP has been chosen as the interfacial layer, owing to its low lattice mismatch with Si. But, microtwins and antiphase boundaries are still difficult to avoid in this system. Absolute quantification of the microtwin volume fraction is used for optimization of the growth procedure in order to eliminate these defects. Lateral correlation lengths associated with mean antiphase boundary distances are then evaluated. Finally, optimized growth conditions lead to the annihilation of antiphase domains within the first 10?nm.

  12. 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.

  13. 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.

  14. Spin injection from Heusler alloys into semiconductors: A materials perspective

    NASA Astrophysics Data System (ADS)

    Farshchi, R.; Ramsteiner, M.

    2013-05-01

    The notion of using electron spins as bits for highly efficient computation coupled with non-volatile data storage has driven an intense international research effort over the past decade. Such an approach, known as spin-based electronics or spintronics, is considered to be a promising alternative to charge-based electronics in future integrated circuit technologies. Many proposed spin-based devices, such as the well-known spin-transistor, require injection of spin polarized currents from ferromagnetic layers into semiconductor channels, where the degree of injected spin polarization is crucial to the overall device performance. Several ferromagnetic Heusler alloys are predicted to be half-metallic, meaning 100% spin-polarized at the Fermi level, and hence considered to be excellent candidates for electrical spin injection. Furthermore, they exhibit high Curie temperatures and close lattice matching to III-V semiconductors. Despite their promise, Heusler alloy/semiconductor heterostructures investigated in the past decade have failed to fulfill the expectation of near perfect spin injection and in certain cases have even demonstrated inferior behavior compared to their elemental ferromagnetic counterparts. To address this problem, a slew of theoretical and experimental work has emerged studying Heusler alloy/semiconductor interface properties. Here, we review the dominant prohibitive materials challenges that have been identified, namely atomic disorder in the Heusler alloy and in-diffusion of magnetic impurities into the semiconductor, and their ensuing detrimental effects on spin injection. To mitigate these effects, we propose the incorporation of half-metallic Heusler alloys grown at high temperatures (>200 °C) along with insertion of a MgO tunnel barrier at the ferromagnet/semiconductor interface to minimize magnetic impurity in-diffusion and potentially act as a spin-filter. By considering evidence from a variety of structural, optical, and electrical studies, we hope to paint a realistic picture of the materials environment encountered by spins upon injection from Heusler alloys into semiconductors. Finally, we review several emerging device paradigms that utilize Heusler alloys as sources of spin polarized electrons.

  15. Metal alloy identifier

    DOEpatents

    Riley, William D. (Avondale, MD); Brown, Jr., Robert D. (Avondale, MD)

    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.

  16. Carrier and Spin Dynamics in InAsP Ternary Alloys

    NASA Astrophysics Data System (ADS)

    Meeker, Michael; McCutcheon, Kelly; Bhowmick, Mithun; Magill, Brenden; Khodaparast, Giti A.; Tischler, Joe G.; Choi, Sukgeun G.; Palmstrøm, Chris J.

    2013-03-01

    The recent rapid progress in the field of spintronics involves extensive measurements of carrier and spin relaxation dynamics in III-V semiconductors. In addition, as the switching rates in electronic and optoelectronic devices are pushed to higher frequencies, it is important to understand carrier dynamic phenomena in semiconductors on femtosecond time-scales. In this work, we employed time and polarization-resolved differential transmission measurements in near and mid-infrared, to probe carrier and spin relaxation times in several InAsP ternary alloys. Our results demonstrate the unique and complex dynamics in this material system that can be important for electronic and optoelectronic devices. We present our experimental observations and compare them with the observations in InAs and InP. The recent rapid progress in the field of spintronics involves extensive measurements of carrier and spin relaxation dynamics in III-V semiconductors. In addition, as the switching rates in electronic and optoelectronic devices are pushed to higher frequencies, it is important to understand carrier dynamic phenomena in semiconductors on femtosecond time-scales. In this work, we employed time and polarization-resolved differential transmission measurements in near and mid-infrared, to probe carrier and spin relaxation times in several InAsP ternary alloys. Our results demonstrate the unique and complex dynamics in this material system that can be important for electronic and optoelectronic devices. We present our experimental observations and compare them with the observations in InAs and InP. Supported by: NSF-Career Award DMR-0846834 and Virginia Tech ICTAS

  17. Weldability of intermetallic alloys

    SciTech Connect

    David, S.A. (Oak Ridge National Lab., TN (United States))

    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.

  18. Alloy phase diagrams

    Microsoft Academic Search

    L. H. Bennett; B. C. Giessen; T. B. Massalski

    1984-01-01

    These proceedings collect papers presented at a symposium on alloy phase diagrams. Topics include: Crystal phase transformations; order-disorder transformations; crystal lattices; metallic glasses; metastable states; solubility; binary alloy systems; and alloys of iron, tantalum, silicon, aluminum, germanium, palladium, copper, and nickel.

  19. Alloys for aerospace

    Microsoft Academic Search

    S. Tuominen; C. Wojcik

    1995-01-01

    Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys

  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. Alloying of aluminum-beryllium alloys

    NASA Astrophysics Data System (ADS)

    Molchanova, L. V.; Ilyushin, V. N.

    2013-01-01

    The existing phase diagrams of Al-Be- X alloys, where X is an alloying element, are analyzed. Element X is noted to poorly dissolve in both aluminum and beryllium. It is shown that the absence of intermetallic compounds in the Al-Be system affects the phase equilibria in an Al-Be- X system. Possible phase equilibria involving phases based on aluminum, beryllium, and intermetallic compounds are proposed, and the types of strengthening of Al-Be alloys by an addition of a third element are classified.

  2. Flexible III-V Multijunction Solar Blanket

    Microsoft Academic Search

    K. M. Edmondson; D. C. Law; G. Glenn; A. Paredes; R. R. King; N. H. Karam

    2006-01-01

    Thin high-efficiency triple junction GalnP\\/GaAs\\/Ge solar cells have been incorporated into prototype flexible blanket coupons with a coupon efficiency of 28% for AMO (0.1353 W\\/cm2) Prototype coupons have a specific power density from 360-500 W\\/kg and may well approach >1000 W\\/kg with further thin cell and blanket fabrication improvements. Initial LIV results are shown for a thin flexible three-cell and

  3. Surface phonons of III-V semiconductors 

    E-print Network

    Das, Pradip Kumar

    1994-01-01

    of the Harten-Toennies mode for GaAs along SY and Yl'. Plot 'a' is the atteunation at 0. 4 of the distance along SY, and 'b' at 0. 6. Plot 'c' is the along halfway between Y and P, and 'd' at 0. 8 of the distance along YF. 'b' is a well defined first layer... 0. 6 of the distance along YF, Ss becomes a resonance. For the rest of the path along YF, Ss continues to be a first layer resonance. At Y, S4 starts as a well defined second layer surface mode; atoms are polarized in SH inode (parallel to the x...

  4. 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.

  5. Development of titanium alloys by the method of complex alloying

    Microsoft Academic Search

    A. I. Khorev

    2006-01-01

    We study the effect of alloying on the mechanical properties of welded joints and base metal of titanium alloys of the system\\u000a Ti-Al-Mo-V-Cr-Fe. We also formulate the theoretical aspects and principles of complex alloying of titanium alloys and the\\u000a theory of alloying of additive materials for the welding of ?-, (? + ?), and ?-alloys. It has been shown that

  6. 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. PMID:18572716

  7. Uranium-titanium-niobium alloy

    Microsoft Academic Search

    Ludtka

    1990-01-01

    This patent describes a uranium alloy having small additions of Ti and Nb. It shows improved strength and ductility in cross-section of greater than one inch over prior uranium alloy having only Ti as an alloy element.

  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. Semiconductor alloy theory

    Microsoft Academic Search

    A. B. Chen

    1986-01-01

    This grant supported our work on semiconductor alloy theory. Many useful results have been obtained, 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 energy, bond length and mixing enthalpy for all

  10. Low activation ferritic alloys

    DOEpatents

    Gelles, David S. (West Richland, WA); Ghoniem, Nasr M. (Granada Hills, CA); Powell, Roger W. (Pasco, WA)

    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.

  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. In situ measurement of CuPt alloy ordering using strain anisotropy

    SciTech Connect

    France, Ryan M.; McMahon, William E.; Kang, Joongoo; Steiner, Myles A.; Geisz, John F. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2014-02-07

    The optical and electrical properties of many III-V alloys change with the degree of CuPt atomic ordering, which is very sensitive to growth conditions. The bulk ordered alloy is elongated along the normal to the ordered planes, and is asymmetrically strained when coherent to a cubic substrate. Here, we demonstrate in situ measurement of the anisotropic strain due to ordering using two-dimensional wafer curvature. The measurement is sensitive to bulk anisotropies, and so is complementary to other in situ measurements that are sensitive to surface anisotropies. Using ab initio calculations, we determine a maximum strain anisotropy of 0.27% between [110] and [1{sup ¯}10] when perfectly ordered single-variant GaInP{sub 2} is coherent to a (001) cubic substrate. We relate the in situ measurement of strain anisotropy on various GaInP{sub 2} samples to ex situ measurements of the order parameter to validate the measurement and confirm the capability to predict material properties. The measurement monitors change in ordering during growth, useful for quickly determining the growth condition dependence of ordering or monitoring order-disorder transitions. More generally, this measurement technique could, in principle, be used to monitor phase changes in any epitaxial system for which the strain anisotropy of the two phases differs.

  13. Copper-tantalum alloy

    DOEpatents

    Schmidt, Frederick A. (Ames, IA); Verhoeven, John D. (Ames, IA); Gibson, Edwin D. (Ames, IA)

    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.

  14. 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.

  15. ZIRCONIUM ALLOYS FOR REACTORS

    Microsoft Academic Search

    Nishihara

    1960-01-01

    The general characteristics of the reactor-grade Zr alloys are revewed, ; including the physical properties of pure Zr and of the pertinent alloys, ; manufacturing processes of Zr sponge and of Zircaloy, electric arc welding ; methods for the pure metal and the ingot, hot and cold working, annealing and ; welding. The high temperatare behavior of Zircaloy, Ozhennite and

  16. Shape Memory Alloys

    Microsoft Academic Search

    Abhijit Bhattacharyya; Dimitris C Lagoudas

    2007-01-01

    This special issue on shape memory alloys (SMA) is an encore to a special issue on the same topic edited by us six years ago (Smart Mater. Struct.9 (5) October 2000). A total of 19 papers is offered in this issue, organized into the three broad categories of modeling, characterization and applications. In addition to thermally activated shape memory alloys,

  17. Rhenium alloys in electronics

    Microsoft Academic Search

    E. M. Savitskii; M. A. Tylkina; A. M. Levin

    1980-01-01

    The book presents information on the utilization of rhenium and its alloys in electronics for electronic vacuum devices such as preheaters, cathodes, and screens, and also in the thin-film microelectronic designs. Data on physical and chemical interaction of rhenium with other elements are generalized, and basic theoretical premises in the development of rhenium alloys with specified properties are summarized. The

  18. 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.

  19. Ductile transplutonium metal alloys

    DOEpatents

    Conner, William V. (Boulder, CO)

    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.

  20. Mechanically alloyed, ferritic oxide dispersion strengthened alloys: structure and properties

    Microsoft Academic Search

    A. Czyrska-Filemonowicz; B. Dubiel

    1997-01-01

    The paper presents information concerning the production of oxide dispersion strengthened (ODS) alloys by mechanical alloying process. The macro- and microstructures of the ferritic ODS alloys, INCOLOY MA 956 and PM2000 are discussed in detail. The basic engineering properties of these alloys, namely oxidation resistance and mechanical properties, especially tensile, compression and high temperature creep, are outlined.

  1. Alloying aluminum alloys with scandium and zirconium additives

    Microsoft Academic Search

    V. G. Davydov; V. I. Elagin; V. V. Zakharov; D. Rostoval

    1996-01-01

    In recent years Russian specialists have developed industrial weldable aluminum alloys alloyed with a small amount of scandium. Scandium added to existing weldable aluminum alloys improves considerably the set of their operational properties. In addition, the presence of scandium makes it possible to create new materials superior to traditional aluminum alloys. The present paper is devoted to problems of simultaneous

  2. Alloys for aerospace

    SciTech Connect

    Tuominen, S.; Wojcik, C. [Teledyne Wah Chang, Albany, OR (United States)

    1995-04-01

    Aerospace industries require special allows with many properties tailored to meet specific needs. Prerequisites include clean melting techniques to maintain low impurity levels, tight control of alloy chemistry, and the analytical capability to characterize the product. Teledyne Wah Chang (TWC) produces specially refractory metals, including zirconium, hafnium, titanium, niobium and vanadium, which are essential components of many aerospace alloys. Alloys are prepared by vacuum-arc-remelting (VAR) or electron beam (EB) melting, and ingots are processed to products ranging from bar and tube stock to wire and foil. Chemical, mechanical, and microstructural tests are all conducted at TWC`s in-house laboratory facilities. Of the alloys described here, Ti-3Al-2.5V, Tiadyne 3515 (Alloy C), NiTiFe, and C-103 are produced commercially, while orthorhombic titanium aluminides are promising candidates for future light-weight composite matrices.

  3. 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.

  4. Integration of GaAsP alloys on SiGe virtual substrates for Si-based dual-junction solar cells

    E-print Network

    Sharma, Prithu

    2013-01-01

    Integration of III-V compound semiconductors with silicon is an area that has generated a lot of interest because III-V materials and Si are best suited for different types of devices. Monolithic integration enables the ...

  5. 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. (Palo Alto, CA)

    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.

  6. 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. (Palo Alto, CA)

    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.

  7. (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. [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States); Jiang, L.; Xu, C.; Smith, D. J.; Menendez, J. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)

    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.

  8. Subtyping in alloy

    E-print Network

    Torlak, Emina, 1979-

    2004-01-01

    A type system for the Alloy modelling language is described that supports subtypes and allows overloading of relation names. No special syntactic features needed to be added to the language to support the type system; there ...

  9. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  10. High temperature niobium alloys

    Microsoft Academic Search

    J. J. Stephens; I. Ahmad

    1991-01-01

    This book covers the following areas regarding high temperature niobium alloys: atomic mass transport of interstitial solutes in niobium; electroplastic effect; dispersion strengthening; dispersion hardening by carbides; tensile behavior of tungsten\\/niobium composites; phase stability; mechanical properties; oxidation.

  11. Ductile ordered intermetallic alloys.

    PubMed

    Liu, C T; Stiegler, J O

    1984-11-01

    Many ordered intermetallic alloys have attractive high-temperature properties; however, low ductility and brittle fracture limit their use for structural applications. The embrittlement in these alloys is mainly caused by an insufficient number of slip systems (bulk brittleness) and poor grain-boundary cohesion. Recent studies have shown that the ductility and fabricability of ordered intermetallics can be substantially improved by alloying processes and control of microstructural features through rapid solidification and thermomechanical treatments. These results demonstrate that the brittleness problem associated with ordered intermetallics can be overcome by using physical metallurgical principles. Application of these principles will be illustrated by results on Ni(3)Al and Ni(3)V-Co(3)V-Fe(3)V. The potential for developing these alloys as a new class of high-temperature structural materials is discussed. PMID:17774926

  12. Mechanical alloying and milling

    Microsoft Academic Search

    C. Suryanarayana

    2001-01-01

    Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from

  13. Thixoforming 7075 aluminium alloys

    Microsoft Academic Search

    S. Chayong; H. V. Atkinson; P. Kapranos

    2005-01-01

    Commercially extruded 7075 alloy (extrusion ratio of 16:1) has been used as a feedstock for thixoforming in order to investigate thixoformability of a high performance aluminium alloy. The microstructure in the semi-solid state consists of fine spheroidal solid grains surrounded by liquid. The results of thixoforming with one step, two-step and three-step induction heating regimes are presented. Typical defects in

  14. 2.2–2.7 ?m side wall corrugated index coupled distributed feedback GaSb based laser diodes

    NASA Astrophysics Data System (ADS)

    Gaimard, Q.; Larrue, A.; Triki, M.; Adelin, B.; Nguyen-Ba, T.; Rouillard, Y.; Gauthier-Lafaye, O.; Teissier, R.; Vicet, A.

    2015-06-01

    We report on the modeling, growth, processing, characterization and integration in a gas detection setup of side wall corrugated distributed feed-back antimonide diode lasers emitting at 2.28 and 2.67 ?m. The laser structures were grown by molecular beam epitaxy on GaSb substrate. Ridge lasers were fabricated from the grown wafers according to the following process: a second order Bragg grating was defined on the sides of the ridges by interferometric lithography, optical lithography and etched in a Cl-based inductively coupled plasma reactor. The devices exhibit a power reaching 40 mW, a side mode suppression ratio better than 28 dB and a tuning range of 3 nm at room temperature. One of these devices was successfully integrated in a tunable diode laser absorption spectroscopy setup, thus demonstrating that they are suitable for gas analysis.

  15. EXAMINATION AND PROPERTIES OF URANIUM ALLOYS

    Microsoft Academic Search

    H. A. Saller; F. A. Rough

    1953-01-01

    The heat treatment, microstructure, hardness, and density data for a ; series of uranium alloys are described. These are alloys which were studied ; because of their potential interest for high-temperature water-corrosion ; resistance. The alloys studied include uranium--zirconium biiiary alloys, ; uranium-- zirconium-base ternary alloys, and uranium --molybdenum alloys. ; (auth);

  16. Quenching Alloys in Containerless Processing

    NASA Technical Reports Server (NTRS)

    Oran, W. A.

    1984-01-01

    Magnetic levitation and gas quenching combined in proposed method to melt and rapidly solidify alloys without contacting container walls. Method used to develop new carbides for drill bits, high-ductility structured steel and new high-strength superplastic alloys.

  17. 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.

  18. Utilization of titanium alloy equipment

    Microsoft Academic Search

    N. M. Shmakov; V. S. Mikheev

    1974-01-01

    Alloys AT-3 and AT-6 have wide application in practice in contrast to many series containing titanium alloyed with cheap obtainable elements such as aluminum, chromium, iron, silicon, and boron. Alloys AT-3 and AT-6 are processable. Extruded electrodes consisting of magnesio-thermic titanium and added alloying elements were fused twice in a vacuum arc furnace in an argon atmosphere. After machining to

  19. TERNARY ALLOY-CONTAINING PLUTONIUM

    Microsoft Academic Search

    Waber

    1960-01-01

    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

  20. ELECTROLESS-PLATED BRAZING ALLOYS

    Microsoft Academic Search

    P. Patriarca; G. M. Slaughter; W. D. Manly

    1957-01-01

    The electroless-plating process deposits an Ni-P brazing alloy that ; exhibits excellent wetability and flowability in conjunction with each high-; temperature alloys as austenitic stainless steels or Inconel when heated above ; the eutectic temperature in a dry hydrogen atmosphere. Complex tubeto-fin heat ; exchanger assemblies can be fabricated by preplating with electroless Ni-P alloy ; and then brazing at

  1. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter (Houston, TX); Koh, Shirlaine (Houston, TX); Mani, Prasanna (Houston, TX); Ratndeep, Srivastava (Houston, TX)

    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.

  2. PLUTONIUM-URANIUM-TITANIUM ALLOYS

    Microsoft Academic Search

    Coffinberry

    1959-01-01

    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

  3. Boron addition to alloys

    SciTech Connect

    Coad, B. C.

    1985-08-20

    A process for addition of boron to an alloy which involves forming a melt of the alloy and a reactive metal, selected from the group consisting of aluminum, titanium, zirconium and mixtures thereof to the melt, maintaining the resulting reactive mixture in the molten state and reacting the boric oxide with the reactive metal to convert at least a portion of the boric oxide to boron which dissolves in the resulting melt, and to convert at least portion of the reactive metal to the reactive metal oxide, which oxide remains with the resulting melt, and pouring the resulting melt into a gas stream to form a first atomized powder which is subsequently remelted with further addition of boric oxide, re-atomized, and thus reprocessed to convert essentially all the reactive metal to metal oxide to produce a powdered alloy containing specified amounts of boron.

  4. Magnesium and magnesium alloys

    SciTech Connect

    Avedesian, M.; Baker, H. [eds.

    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.

  5. Noble alloys in dentistry.

    PubMed

    Gettleman, L

    1991-04-01

    Noble metals used for dental castings continue to consist of alloys of gold, palladium, and silver (not a noble metal), with smaller amounts of iridium, ruthenium, and platinum. The majority are used as a backing for ceramic baking, with the rest used as inlays, onlays, and unveneered crowns. Base metal alloys, principally made of nickel, chromium, and beryllium have gained widespread usage, especially in the United States, due to their lower cost and higher mechanical properties. The current literature, for the most part, cites the use of noble alloys as controls for trials of alternative materials. Direct gold (gold foil) still retains a following and a number of new patents were founded. PMID:1777669

  6. 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.

  7. Microstructural studies on Alloy 693

    NASA Astrophysics Data System (ADS)

    Halder, R.; Dutta, R. S.; Sengupta, P.; Samajdar, I.; Dey, G. K.

    2014-10-01

    Superalloy 693, is a newly identified ‘high-temperature corrosion resistant alloy’. Present study focuses on microstructure and mechanical properties of the alloy prepared by double ‘vacuum melting’ route. In general, the alloy contains ordered Ni3Al precipitates distributed within austenitic matrix. M6C primary carbide, M23C6 type secondary carbide and NbC particles are also found to be present. Heat treatment of the alloy at 1373 K for 30 min followed by water quenching (WQ) brings about a microstructure that is free from secondary carbides and Ni3Al type precipitates but contains primary carbides. Tensile property of Alloy 693 materials was measured with as received and solution annealed (1323 K, 60 min, WQ) and (1373 K, 30 min, WQ) conditions. Yield strength, ultimate tensile strength (UTS) and hardness of the alloy are found to drop with annealing. It is noted that in annealed condition, considerable cold working of the alloy can be performed.

  8. Band structure properties of novel BxGa1-xP alloys for silicon integration

    NASA Astrophysics Data System (ADS)

    Hossain, Nadir; Hosea, T. J. C.; Sweeney, Stephen J.; Liebich, Sven; Zimprich, Martin; Volz, Kerstin; Kunert, Bernardette; Stolz, Wolfgang

    2011-09-01

    We have grown and investigated the band-structure properties of novel III-V alloys based upon BxGa1-xP. These layers are utilized as strain-compensating layers for the lattice-matched integration of novel direct bandgap Ga(NAsP) quantum well lasers on silicon. Experimental and theoretical studies reveal the dependence of the direct and indirect band gaps for strained BxGa1-xP layers grown on silicon as a function of Boron composition from which we derive the properties of free-standing BxGa1-xP. For Boron fractions up to 6%, we find that the bowing parameter for the lowest (indirect) band gap is - 6.2 ± 0.2 eV. High crystalline quality and promising optical material properties are demonstrated and applied to monolithically integrated Ga(NAsP)/(BGa)P multi-quantum well heterostructures on (001) silicon substrates. Our results show that novel (BGa)P layers are suitable for strain compensation purposes, which pave the way towards a commercial solution for the monolithic integration of long term stable laser diodes on silicon substrates.

  9. Lasing in direct-bandgap GeSn alloy grown on Si

    NASA Astrophysics Data System (ADS)

    Wirths, S.; Geiger, R.; von den Driesch, N.; Mussler, G.; Stoica, T.; Mantl, S.; Ikonic, Z.; Luysberg, M.; Chiussi, S.; Hartmann, J. M.; Sigg, H.; Faist, J.; Buca, D.; Grützmacher, D.

    2015-02-01

    Large-scale optoelectronics integration is limited by the inability of Si to emit light efficiently, because Si and the chemically well-matched Ge are indirect-bandgap semiconductors. To overcome this drawback, several routes have been pursued, such as the all-optical Si Raman laser and the heterogeneous integration of direct-bandgap III–V lasers on Si. Here, we report lasing in a direct-bandgap group IV system created by alloying Ge with Sn without mechanically introducing strain. Strong enhancement of photoluminescence emerging from the direct transition with decreasing temperature is the signature of a fundamental direct-bandgap semiconductor. For T???90?K, the observation of a threshold in emitted intensity with increasing incident optical power, together with strong linewidth narrowing and a consistent longitudinal cavity mode pattern, highlight unambiguous laser action. Direct-bandgap group IV materials may thus represent a pathway towards the monolithic integration of Si-photonic circuitry and complementary metal–oxide–semiconductor (CMOS) technology.

  10. METALLOGRAPHY OF TITANIUM ALLOYS

    Microsoft Academic Search

    H. R. Ogden; F. C. Holden

    1958-01-01

    Because of the importance of mnetalography to the technolagy of titanium ; and because of the current interest in titanium technology, it is essential that ; the metallurgists working with titanium understand its metallography. In this ; report emphasis is placed on the microstructures of titanium and its alloys. The ; report contains both a general description of titanium metallegraphy

  11. 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.

  12. 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.

  13. Quinary metallic glass alloys

    DOEpatents

    Lin, Xianghong (Pasadena, CA); Johnson, William L. (Pasadena, CA)

    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.

  14. 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.

  15. Corrosion resistant austenitic alloy

    Microsoft Academic Search

    T. A. DeBold; D. G. Frick; J. S. Kutzamanis

    1984-01-01

    An austenitic stainless corrosion resistant alloy and articles made therefrom having good resistance to pitting and crevice corrosion in oxidizing chloride-bearing media combined with resistance to general corrosion and to intergranular corrosion in oxidizing media containing C, Mn, Si, P, S, Cr, Ni, Mo, Cu, N, B, Ce, La, Nb, Ti and the balance iron. The amount of nitrogen is

  16. Casting Characteristics of Aluminum Die Casting Alloys

    Microsoft Academic Search

    Makhlouf M. Makhlouf; Diran Apelian

    2002-01-01

    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

  17. Investigation of HVOF spraying on magnesium alloys

    Microsoft Academic Search

    Maria Parco; Lidong Zhao; Jochen Zwick; Kirsten Bobzin; Erich Lugscheider

    2006-01-01

    Magnesium alloys are promising alternatives to other lightweight alloys such as aluminum alloys due to their high specific strength and stiffness. However, the use of magnesium alloys is limited by their poor wear behaviour and corrosion performance. Recent studies have shown an enormous potential of thermal spray techniques for the surface modification of Mg alloys. The high particle velocities and

  18. Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying

    E-print Network

    Zheng, Yufeng

    Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying and Hot IsostaticNb-6Zr (at.%) shape memory alloys produced using elemental powders by means of mechanical alloying strength. Keywords hot isostatic pressing, mechanical alloying, shape memory alloy 1. Introduction Porous

  19. Structure of dental gallium alloys.

    PubMed

    Herø, H; Simensen, C J; Jørgensen, R B

    1996-07-01

    The interest in gallium alloys as a replacement for amalgam has increased in recent years due to the risk of environmental pollution from amalgam. Alloy powders with compositions close to those for alloys of amalgam are mixed with a liquid gallium alloy. The mix is condensed into a prepared cavity in much the same way as for amalgam. The aim of the present work was to study the structure of: (1) two commercial alloy powders containing mainly silver, tin and copper, and (2) the phases formed by mixing these powders with a liquid alloy of gallium, indium and tin. One of the alloy powders contained 9 wt% palladium. Cross-sections of cylindrical specimens made by these gallium mixes were investigated by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Discrete grains of the following phases were found to be present in both gallium alloys: hexagonal Ag2Ga, tetragonal Cu(Pd)Ga2, cubic Ag9In4 and tetragonal beta-Sn. Indications of hexagonal or orthorhombic Ag2Sn were found in the remaining, unreacted alloy particles. In the palladium-containing alloy the X-ray reflections indicate a minor fraction of cubic Cu9Ga4 in addition to the Cu(Pd)Ga2 phase. Particles of beta-Sn are probably precipitated because Sn-Ga phases cannot be formed according to the binary phase diagram. PMID:8805980

  20. Laser surface alloying of silicon into aluminum casting alloys

    Microsoft Academic Search

    Zhiyue Xu; Keng H. Leong; Paul G. Sanders

    2000-01-01

    Aluminum alloys that are easily castable tend to have lower silicon content, and hence, lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:yttrium-aluminum-garnet laser with fiber-optic beam delivery was used

  1. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

    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.

  2. Alloys for crown and bridgework.

    PubMed

    Brockhurst, P J; Cannon, R W

    1981-10-01

    The requirements of alloys for metal-ceramic crowns and bridgework are examined. The functional requirements and manipulative behaviour and cost of cheaper alternatives to high gold alloys are discussed. All types use--high gold, reduced gold, silver palladium and base metal--appear to function satisfactorily in the mouth. Nickel and beryllium do not appear to be health hazards. Dental laboratory procedures and materials must be chosen to suit the type of alloy employed, although all alloy types appear suitable for crown and bridgework. The cost of alloy must be carefully examined in the context of total cost to the patient, and the use of alternatives to gold alloys in many cases may not warrant the required changes to laboratory procedures, but the saving is real, and can make permanent restorations available to greater proportion of the community. PMID:7036968

  3. Two phase titanium aluminide alloy

    DOEpatents

    Deevi, Seetharama C. (Midlothian, VA); Liu, C. T. (Oak Ridge, TN)

    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.

  4. Magnesium-lithium casting alloys

    NASA Technical Reports Server (NTRS)

    Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

    1974-01-01

    The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

  5. 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.

  6. Alloys based on nickel aluminides

    Microsoft Academic Search

    V. P. Buntushkin; E. N. Kablov; O. A. Bazyleva; G. I. Morozova

    1999-01-01

    The possibility of replacing commercial high-termperature alloys of the ZhS6U type by alloys based on nickel aluminides is\\u000a considered. A complex study of alloys based on nickel aluminide has been conducted with determination of ways to increase\\u000a their ductility, heat-resistance, and strength in a wide range of operating temperatures.

  7. Amorphous metal alloy and composite

    DOEpatents

    Wang, Rong (Richland, WA); Merz, Martin D. (Richland, WA)

    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.

  8. 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.

  9. Shape memory alloy actuator

    DOEpatents

    Varma, Venugopal K. (Knoxville, TN)

    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.

  10. 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.

  11. The manufacture of superplastic alloys

    NASA Astrophysics Data System (ADS)

    Grimes, R.

    1987-08-01

    Amongst aluminum alloys, the Al-6 percent Cu-0.4 percent Zr system that typifies the Supral alloys requires a specially developed casting system in order to achieve a very high level of supersaturation with zirconium. Subsequent manufacturing is fairly conventional, the sheet product recrystallizing dynamically during superplastic forming. The higher strength aluminum alloys are conventionally cast but achieve a very fine grain size at sheet stage by careful thermal mechanical treatment during the later stages of semi-fabrication. With titanium, the standard production route for the Ti-6Al-4V alloy results in a product with superplastic capabilities perfectly adequate for most applications.

  12. DIMENSIONALLY STABLE URANIUM ALLOYS. III. URANIUM-CARBON ALLOYS

    Microsoft Academic Search

    I. Sheinhartz; J. L. Zambrow

    1959-01-01

    In an attempt to improve the strength at elevated temperatures of a 1.5% ; molybdenum in uranium alloy, a network of uranium carbide was incorporated within ; the structure of the alloy by use of powder-metallurgical techniques. ; Compositions containing up to 10% uranium carbide were evaluated by the use of ; hot hardness tests at temperatures up to 700

  13. 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.

  14. The fractography of casting alloys

    Microsoft Academic Search

    G POWELL

    1994-01-01

    Several types of casting alloys were fractured using various loading modes (uniaxial tension, bending, impact, and torsion, and cyclic stressing), and the corresponding mechanical properties were determined. The unetched and etched fracture surfaces and the microstructures were examined using conventional techniques. The types of casting alloys that were the subjects f these investigations include gray iron, ductile iron, cast steel,

  15. 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.

  16. MEMORANDUM ON URANIUM TITANIUM ALLOYS

    Microsoft Academic Search

    Wyman

    1949-01-01

    A series of four U--Ti alloys containing 15, 26.4, 35, and 45 wt.% Ti ; were run in the precision differential dilatometer. With the possible exception ; of the high temperature transformation in the 15% Ti alloy, all the changes took ; place over an appreciable range of temperature. (W.L.H.)

  17. 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.

  18. Irradiation Resistance of Multicomponent Alloys

    NASA Astrophysics Data System (ADS)

    Egami, T.; Guo, W.; Rack, P. D.; Nagase, T.

    2014-01-01

    High-entropy alloys (HEAs) are characterized not only by high values of entropy but also by high atomic-level stresses originating from mixing of elements with different atomic sizes. Particle irradiation on solids produces atomic displacements and thermal spikes. The high atomic-level stresses in HEAs facilitate amorphization upon particle irradiation, followed by local melting and re-crystallization due to thermal spikes. We speculate that this process will leave much less defects in HEAs than in conventional alloys. For this reason, they may be excellent candidates as new nuclear materials. We discuss initial results of computer simulation on model binary alloys and an electron microscopy study on Zr-Hf-Nb alloys, which demonstrate extremely high irradiation resistance of these alloys against electron damage to support this speculation.

  19. Normal evaporation of binary alloys

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

    In the study of normal evaporation, it is assumed that the evaporating alloy is homogeneous, that the vapor is instantly removed, and that the alloy follows Raoult's law. The differential equation of normal evaporation relating the evaporating time to the final solute concentration is given and solved for several important special cases. Uses of the derived equations are exemplified with a Ni-Al alloy and some binary iron alloys. The accuracy of the predicted results are checked by analyses of actual experimental data on Fe-Ni and Ni-Cr alloys evaporated at 1600 C, and also on the vacuum purification of beryllium. These analyses suggest that the normal evaporation equations presented here give satisfactory results that are accurate to within an order of magnitude of the correct values, even for some highly concentrated solutions. Limited diffusion and the resultant surface solute depletion or enrichment appear important in the extension of this normal evaporation approach.

  20. 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.

  1. Stress Corrosion Cracking of Certain Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Hasse, K. R.; Dorward, R. C.

    1983-01-01

    SC resistance of new high-strength alloys tested. Research report describes progress in continuing investigation of stress corrosion (SC) cracking of some aluminum alloys. Objective of program is comparing SC behavior of newer high-strength alloys with established SC-resistant alloy.

  2. Manufacturing development of low activation vanadium alloys

    Microsoft Academic Search

    J. P. Smith; W. R. Johnson; C. B. Baxi

    1996-01-01

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of

  3. Physical metallurgy of recycling wrought aluminum alloys

    Microsoft Academic Search

    J. B. Hess

    1983-01-01

    It is quite characteristic of aluminum alloys that if the amount of any element addition is gradually increased, then an upper limit (a tolerance limit) is eventually reached where some important aspect of the alloy's overall behavior is affected harmfully. Although alloy compositional registers and specifications commonly list upper limits for only the main alloying additions and usual impurities, in

  4. Towards an Operational Semantics for Alloy

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, Theophilos; Dougherty, Daniel J.; Fisler, Kathi; Krishnamurthi, Shriram

    The Alloy modeling language has a mathematically rigorous denotational semantics based on relational algebra. Alloy specifications often represent operations on a state, suggesting a transition-system semantics. Because Alloy does not intrinsically provide a notion of state, however, this interpretation is only implicit in the relational-algebra semantics underlying the Alloy Analyzer.

  5. High-Alloy Materials for Offshore Applications

    Microsoft Academic Search

    T. F. Lemke; J. A. Harris

    1983-01-01

    High-alloy materials possessing good corrosion resistance in hot, sour brines are being seriously considered for offshore applications. These alloys are available in a wide range of strength levels which can be attained by the methods of cold working or precipitation hardening. Results of testing INCONEL alloys 625 and 718 and INCOLOY alloys 825 and 925 for resistance to general corrosion,

  6. (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 [Departamento de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain); Mesa, Jose L. [Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain)], E-mail: joseluis.mesa@ehu.es; Pizarro, Jose L.; Bazan, Begona [Departamento de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain); Ruiz de Larramendi, Idoia [Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain); Arriortua, Maria I. [Departamento de Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain); Rojo, Teofilo [Departamento de Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/EHU, Apdo. 644, E-48080 Bilbao (Spain)

    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}].

  7. Oxidation resistant alloys, method for producing oxidation resistant alloys

    SciTech Connect

    Dunning, John S. (Corvallis, OR); Alman, David E. (Salem, OR)

    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

  8. New Amorphous Silicon Alloy Systems

    NASA Astrophysics Data System (ADS)

    Kapur, Mridula N.

    1990-01-01

    The properties of hydrogenated amorphous silicon (a-Si:H) have been modified by alloying with Al, Ga and S respectively. The Al and Ga alloys are in effect quaternary alloys as they were fabricated in a carbon-rich discharge. The alloys were prepared by the plasma assisted chemical vapor deposition (PACVD) method. This method has several advantages, the major one being the relatively low defect densities of the resulting materials. The PACVD system used to grow the alloy films was designed and constructed in the laboratory. It was first tested with known (a-Si:H and a-Si:As:H) materials. Thus, it was established that device quality alloy films could be grown with the home-made PACVD setup. The chemical composition of the alloys was characterized by secondary ion mass spectrometry (SIMS), and electron probe microanalysis (EPMA). The homogeneous nature of hydrogen distribution in the alloys was established by SIMS depth profile analysis. A quantitative analysis of the bulk elemental content was carried out by EPMA. The analysis indicated that the alloying element was incorporated in the films more efficiently at low input gas concentrations than at the higher concentrations. A topological model was proposed to explain the observed behavior. The optical energy gap of the alloys could be varied in the 0.90 to 1.92 eV range. The Al and Ga alloys were low band gap materials, whereas alloying with S had the effect of widening the energy gap. It was observed that although the Si-Al and Si-Ga alloys contained significant amounts of C and H, the magnitude of the energy gap was determined by the metallic component. The various trends in optical properties could be related to the binding characteristics of the respective alloy systems. A quantitative explanation of the results was provided by White's tight binding model. The dark conductivity-temperature dependence of the alloys was examined. A linear dependence was observed for the Al and Ga systems. Electronic conduction in the S-alloys appeared to proceed by a two step mechanism. The thermal activation energies for the high Al content and S-alloys were close to half the band gap value. The photoresponse of the films was determined from the light to dark conductivity ratio. The best photoresponse (sigma_ {L}/sigma_{D} = 4 times 10^2) was obtained for the Si-S alloys showing that they are promising electrode materials for solar cell application. A single unit photovoltaic electrolyzer was constructed by combining a-Si:H solar cells with an electrolysis cell. Several different configurations ((PIN), (PIN)^2 , and (PIN)^3) of the solar cells were tested. Both electric power and chemical energy (H_2) could be simultaneously drawn from the electrolyzer.

  9. Physical metallurgy of recycling wrought aluminum alloys

    Microsoft Academic Search

    J. B. Hess

    1983-01-01

    It is quite characteristic of aluminum alloys that if the amount of any element addition is gradually increased, then an upper\\u000a limit (a tolerance limit) is eventually reached where some important aspect of the alloy’s overall behavior is affected harmfully.\\u000a Although alloy compositional registers and specifications commonly list upper limits for only the main alloying additions\\u000a and usual impurities, in

  10. 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.

  11. Heat storage in alloy transformations

    NASA Astrophysics Data System (ADS)

    Birchenall, C. E.

    1980-04-01

    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.

  12. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  13. Processing of aluminium alloys containing titanium addition by mechanical alloying

    Microsoft Academic Search

    K. R. Cardoso; C. A. D. Rodrigues; W. J. Botta F

    2004-01-01

    In this work, mechanical alloying was used to produce precursor powders of 2024 and 7050 aluminium alloys containing titanium addition. Milling was performed in a planetary mill using a ball to powder weight ratio of 20:1 and a milling time varying from 10 to 100h. Characterisation of the milled powders was performed by X-ray diffraction (XRD), differential scanning calorimetry (DSC)

  14. [MRO] Oligocrystalline Shape Memory Alloys

    E-print Network

    Chen, Ying

    Copper-based shape memory alloys (SMAs) exhibit excellent shape memory properties in single crystalline form. However, when they are polycrystalline, their shape memory properties are severely compromised by brittle fracture ...

  15. Tritium Production from Palladium Alloys

    SciTech Connect

    Claytor, T.N.; Schwab, M.J.; Thoma, D.J.; Teter, D.F.; Tuggle, D.G.

    1998-04-19

    A number of palladium alloys have been loaded with deuterium or hydrogen under low energy bombardment in a system that allows the continuous measurement of tritium. Long run times (up to 200 h) result in an integration of the tritium and this, coupled with the high intrinsic sensitivity of the system ({approximately}0.1 nCi/l), enables the significance of the tritium measurement to be many sigma (>10). We will show the difference in tritium generation rates between batches of palladium alloys (Rh, Co, Cu, Cr, Ni, Be, B, Li, Hf, Hg and Fe) of various concentrations to illustrate that tritium generation rate is dependent on alloy type as well as within a specific alloy, dependent on concentration.

  16. 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.

  17. Volatilization from PCA steel alloy

    SciTech Connect

    Hagrman, D.L.; Smolik, G.R.; McCarthy, K.A.; Petti, D.A. [Lockheed Martin Idaho Technologies Company, Idaho Falls, ID (United States)

    1996-12-31

    The mobilizations of key components from Primary Candidate Alloy (PCA) steel alloy have been measured with laboratory-scale experiments. The experiments indicate most of the mobilization from PCA steel is due to oxide formation and spalling but that the spalled particles are large enough to settle rapidly. Based on the experiments, models for the volatilization of iron, manganese, and cobalt from PCA steel in steam and molybdenum from PCA steel in air have been derived. 6 refs., 3 figs.

  18. Sintered titanium carbide hard alloys

    Microsoft Academic Search

    G. V. Samsonov; N. N. Sergeev; G. T. Dzodziev; V. K. Vitryanyuk; L. V. Latyaeva

    1971-01-01

    1.A study was made of the preparation of titanium carbide hard alloys with a nickel binder. It is shown that satisfactory mechanical properties (bend strength 107–115 kg\\/mm2, hardness 90–90.5 HRA) are exhibited by 80% TiC-20% Ni alloys produced from fine-milled mixtures by sintering in a vacuum of 5·10-3 mm Hg at a temperature of 1300‡C and an isothermal holding time

  19. Castable hot corrosion resistant alloy

    NASA Technical Reports Server (NTRS)

    Barrett, Charles A. (inventor); Holt, William H. (inventor)

    1988-01-01

    Some 10 wt percent nickel is added to an Fe-base alloy which has a ferrite microstructure to improve the high temperature castability and crack resistance while about 0.2 wt percent zirconium is added for improved high temperatur cyclic oxidation and corrosion resistance. The basic material is a high temperature FeCrAl heater alloy, and the addition provides a material suitable for burner rig nozzles.

  20. The mechanism of mechanical alloying

    Microsoft Academic Search

    J. S. Benjamin; T. E. Volin

    1974-01-01

    The mechanical alloying process is a new method for producing composite metal powders with controlled microstructures. It\\u000a is unique in that it is an entirely solid state process, permitting dispersion of insoluble phases such as refractory oxides\\u000a and addition of reactive alloying elements such as aluminum and titanium. Interdispersion of the ingredients occurs by repeated\\u000a cold welding and fracture of

  1. Overview of ODS Alloy Development

    Microsoft Academic Search

    Ian G Wright; Bruce A Pint

    2005-01-01

    The overall goal of this effort is to address the materials-related barriers to expediting the use of oxide dispersion-strengthened (ODS) alloys in components required in the U.S. Department of Energy's (DOE's) Office of Fossil Energy's advanced coal combustion, gasification, and utilization processes to operate at temperatures higher than are possible with conventionally-strengthened alloys. The project is focused on the needs

  2. Superplastic forming of alloy 718

    SciTech Connect

    Smith, G.D.; Flower, H.L. (Inco Alloys International Inc., Huntington, WV (United States))

    1994-04-01

    Inconel Alloy 718 (UNS N07718) is now available in a fine-grained, controlled composition modification that can be super-plastically formed. The new superplastic forming (SPF) capability allows the manufacture of large, complex, and detailed parts, which improves integrity by reducing the need for joining. Furthermore, it allows designers to fabricate components having higher strength, fatigue resistance, and temperature capability than parts made of aluminum or titanium alloys.

  3. 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.

  4. 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.

  5. Lithium alloy anode for thermal cells

    SciTech Connect

    Cupp, E.B.; Cottingham, D.R.

    1986-12-02

    This patent describes as an article of manufacture, an anode wafer for a thermal cell, the anode wafer comprising particles of a lithium anode alloy bonded with particles of a metal binder, the lithium anode alloy being of the class consisting of lithium-aluminum alloys; lithium-silicon alloys; and lithium-boron alloys, the metal binder being of the class consisting of unalloyed iron, copper, nickel, manganese; and mixtures thereof, and wherein substantially all the metal binder in the wafer remains present as a discrete phase, unalloyed with the lithium alloy.

  6. Space applications of shape memory alloys 

    E-print Network

    Godard, Olivier Jean

    2002-01-01

    This work presents an investigation of two new possible space applications of shape memory alloys. The first application uses these alloys as active devices to optimally reorient solar panels in space. The thermal issues related to the actuation...

  7. Lower-cost tungsten-rhenium alloys

    NASA Technical Reports Server (NTRS)

    Klopp, W. D.; Raffo, P. L.; Witzke, W. R.

    1966-01-01

    Tungsten-rhenium alloys with a substantially more dilute rhenium content have ductilities and other mechanical properties which compare favorably with the tungsten-rhenium alloys having much higher concentrations of the costly rhenium.

  8. 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.

  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. PMID:26023135

  10. Quasicrystal-reinforced Mg alloys

    NASA Astrophysics Data System (ADS)

    Kim, Young Kyun; Kim, Won Tae; Hyang Kim, Do

    2014-04-01

    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 + ?-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 ?-Mg matrix.

  11. 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.

  12. Fatigue behavior of titanium alloys

    SciTech Connect

    Boyer, R.R.; Eylon, D.; Luetjering, G. [eds.

    1999-07-01

    This symposium was international in nature, with leaders in the fields of fatigue technology and the metallurgy of titanium from the US, Europe and Asia. It covered basic research, development, applications and modeling--life predictions and design of both fatigue crack initiation and propagation of titanium alloys. There were presentations on the full range of titanium alloy systems, from commercially pure and {alpha}-alloys, {alpha}/{beta}- and {beta}-alloys to the gamma titanium aluminides. The effects of processing/heat treatment/microstructure on the fatigue properties were discussed, and models proposed to correlate the microstructures to the observed fatigue performance. Test environments reported on included hard vacuum (and the effect of vacuum level), vacuums with partial pressures of miscellaneous gases, lab air and aqueous media. A session was devoted to the effects of environment and fatigue enhancement via surface treatments using techniques such as shot peening and roller burnishing. The effects of dwell on both S-N and crack growth rate behavior were covered. It was a very comprehensive symposium with presentations from academia, government laboratories and industry, with industrial participants ranging from the petroleum industry to medical and aerospace interests. This book has been separated into four sections, representing the technology areas covered in various sessions, namely Mechanisms of Fatigue crack Initiation and Propagation of Conventional Alloys, Fatigue in Intermetallics, Environmental and Surface Aspects of Fatigue, and Application, Life Prediction and Design. Separate abstracts were prepared for most papers in this volume.

  13. Fusion boundary microstructure evolution in aluminum alloys

    Microsoft Academic Search

    Anastasios Dimitrios Kostrivas

    2000-01-01

    A melting technique was developed to simulate the fusion boundary of aluminum alloys using the GleebleRTM thermal simulator. Using a steel sleeve to contain the aluminum, samples were heated to incremental temperatures above the solidus temperature of a number of alloys. In alloy 2195, a 4wt%Cu-1wt%Li alloy, an equiaxed non-dendritic zone (EQZ) could be formed by heating in the temperature

  14. Caldron For High-Temperature Alloys

    NASA Technical Reports Server (NTRS)

    Geringer, Henry J.

    1989-01-01

    Induction-heated caldron melts high-temperature alloys. Prevents sort of contamination of melts occurring during arc melting in ceramic crucibles. Liquefies 200 grams of solid metal components of alloy like niobium aluminum and makes alloy homogeneous in less than 3 minutes. Plugged sleeve constitutes main body of caldron. Coolant flows through sleeve to prevent it from melting. Mandrel-wound induction coils adjusted to tune source of power. Also serves as mold for casting alloys into such shapes as bars.

  15. Zinc alloy enhances strength and creep resistance

    SciTech Connect

    Machler, M. [Fisher Gauge Ltd., Peterborough, Ontario (Canada). Fishercast Div.

    1996-10-01

    A family of high-performance ternary zinc-copper-aluminum alloys has been developed that provides higher strength, hardness, and creep resistance than the traditional zinc-aluminum alloys Zamak 3, Zamak 5, and ZA-8. Designated ACuZinc, mechanical properties comparable to those of more expensive materials make it suitable for high-load applications and those at elevated temperatures. This article describes the alloy`s composition, properties, and historical development.

  16. 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. PMID:8462293

  17. 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.

  18. Semiconductor-bonded III–V multijunction space solar cells

    Microsoft Academic Search

    D. C. Law; D. M. Bhusari; S. Mesropian; J. C. Boisvert; W. D. Hong; A. Boca; D. C. Larrabee; C. M. Fetzer; R. R. King; N. H. Karam

    2009-01-01

    Boeing-Spectrolab recently demonstrated monolithic 5-junction space solar cells using direct semiconductor-bonding technique. The direct-bonded 5-junction cells consist of (Al)GaInP, AlGa(In)As, Ga(In)As, GaInPAs, and GaIn(P)As subcells deposited on GaAs or Ge and InP substrates. Large-area, high-mechanical strength, and low-electrical resistance direct-bonded interface was achieved to support the high-efficiency solar cell structure. Preliminary 1-sun AM0 testing of the 5-junction cells showed encouraging

  19. III-V Solar Cells and Concentrator Arrays

    Microsoft Academic Search

    Z. I. Alferov; V. M. Andreev; V. D. Rumyantsev

    Semiconductor heterostructures allow us to solve the problems of controlling the fundamental parameters of the semiconductor\\u000a devices. These heterostructures provide the ability to change the electronic band structure, band gaps and refractive indices\\u000a of the material itself during epitaxial growth, as well as to control the effective masses and mobilities of the charge carriers\\u000a in it. The development of the

  20. III-V Solar Cells and Concentrator Arrays

    Microsoft Academic Search

    Z. I. Alferov; V. M. Andreev; V. D. Rumyantsev

    2009-01-01

    Semiconductor heterostructures allow us to solve the problems of controlling the fundamental parameters of the semiconductor devices. These heterostructures provide the ability to change the electronic band structure, band gaps and refractive indices of the material itself during epitaxial growth, as well as to control the effective masses and mobilities of the charge carriers in it. The development of the

  1. Ion implantation and annealing studies in III-V nitrides

    SciTech Connect

    Zolper, J.C. [Sandia National Labs., Albuquerque, NM (United States); Pearton, S.J. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Williams, J.S.; Tan, H.H. [Australian National Univ., Canberra (Australia). Dept. of Electronic Materials Engineering; Karlicek, R.J. Jr.; Stall, R.A. [Emcore Corp., Somerset, NJ (United States)

    1996-12-31

    Ion implantation doping and isolation is expected to play an enabling role for the realization of advanced III-Nitride based devices. In fact, implantation has already been used to demonstrate n- and p-type doping of GaN with Si and Mg or Ca, respectively, as well as to fabricate the first GaN junction field effect transistor. Although these initial implantation studies demonstrated the feasibility of this technique for the III-Nitride materials, further work is needed to realize its full potential. After reviewing some of the initial studies in this field, the authors present new results for improved annealing sequences and defect studies in GaN. First, sputtered AlN is shown by electrical characterization of Schottky and Ohmic contacts to be an effect encapsulant of GaN during the 1,100 C implant activation anneal. The AlN suppresses N-loss from the GaN surface and the formation of a degenerate n{sup +}-surface region that would prohibit Schottky barrier formation after the implant activation anneal. Second, they examine the nature of the defect generation and annealing sequence following implantation using both Rutherford Backscattering (RBS) and Hall characterization. They show that for a Si-dose of 1 x 10{sup 16} cm{sup {minus}2} 50% electrical donor activation is achieved despite a significant amount of residual implantation-induced damage in the material.

  2. 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.

  3. Unidirectional III-V microdisk lasers heterogeneously integrated on SOI.

    PubMed

    Mechet, P; Verstuyft, S; de Vries, T; Spuesens, T; Regreny, P; Van Thourhout, D; Roelkens, G; Morthier, G

    2013-08-12

    We demonstrate unidirectional bistability in microdisk lasers electrically pumped and heterogeneously integrated on SOI. The lasers operate in continuous wave regime at room temperature and are single mode. Integrating a passive distributed Bragg reflector (DBR) on the waveguide to which the microdisk is coupled feeds laser emission back into the laser cavity. This introduces an extra unidirectional gain and results in unidirectional emission of the laser, as demonstrated in simulations as well as in experiment. PMID:23938850

  4. 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.

  5. III-V Nanowires—Extending a Narrowing Road

    Microsoft Academic Search

    Lars-Erik Wernersson; Claes Thelander; Erik Lind; Lars Samuelson

    2010-01-01

    Semiconductor nanowires have attracted considerable attention during the last decade and are considered as an alternative path to extend the road for scaled semiconductor devices. The interest is motivated by the improved electrostatic control in the cylindrical geometry and the possibility to utilize heterostructures in transistor design. Currently, nanowire transistors have been realized both in III-Vs and in group IV

  6. Multijunction III-V solar cells: recent and projected results

    Microsoft Academic Search

    H. F. MacMillan; H. C. Hamaker; G. F. Virshup; J. G. Werthen

    1988-01-01

    The authors discuss Varian's strategy for developing high-efficiency multijunction cells. Cell performance data are reviewed and compared to computer modeling performance projections for two and three-junction cascade cells. Results are presented for single-junction and multijunction monolithic structures fabricated with the AlGaAs-GaAs-InGaAs materials system grown by metal-organic chemical vapor deposition. The problems and progress for lattice-matched and lattice-mismatched structures and cell

  7. Elastic constants of nanoporous III-V semiconductors

    NASA Astrophysics Data System (ADS)

    Janovská, Michaela; Sedlák, Petr; Kruisová, Alena; Seiner, Hanuš; Landa, Michal; Grym, Jan

    2015-06-01

    Resonant ultrasound spectroscopy is applied to determine elastic constants of nanoporous gallium arsenide and indium phosphide single crystals with various pore morphologies. Three samples with approximately the same level of porosity (30%) are studied; it is shown that in all cases this porosity leads to a decrease of Young’s moduli by more than 50% and to a significant increase of the Poisson’s ratios, while the strength of the resulting elastic anisotropy of the nanoporous material follows from the particular morphology of the pores. The experimentally obtained elastic constants are compared to those predicted for the given morphologies by finite elements modeling. It is observed that the numerical models give acceptably realistic predictions of the elastic constants, although they tend to underestimate the decrease of the elastic moduli due to the porosity as well as the corresponding increase of the Poisson’s ratio.

  8. Lightweight, Flexible, High-Efficiency III-V Multijunction Cells

    Microsoft Academic Search

    Daniel C. Law; K. M. Edmondson; N. Siddiqi; A. Paredes; R. R. King; G. Glenn; E. Labios; M. H. Haddad; T. D. Isshiki; N. H. Karam

    2006-01-01

    Large-area (26.6 cm2), thin GaInP\\/GaInAs\\/Ge triple-junction (TJ) solar cells with thickness as low as 50 mum were demonstrated. The average conversion efficiency of fifty thin TJ cells is 28 %, 1-sun AMO. The thin TJ cells showed nominal performance after welding of interconnects and flexibility test (50 mm curvature radius). Prototype coupons made with these thin TJ cells met flexible

  9. III-V 4D Transistors J. J. Gu 1)

    E-print Network

    in HCl:H2O (1:2) solution for nanowire release. The HCl based solution selectively removes the InP. Fabrication started with a 2 inch semi-insulating InP (100) substrate. As shown in Fig. 1(a), the following layers were grown sequentially on the InP substrate: a 100nm undoped InAlAs etch stop layer, an 80nm

  10. Piezoelectricity and growth polarization in III-V nitrides

    Microsoft Academic Search

    Philip Ross Tavernier

    2002-01-01

    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

  11. [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 patients? 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. PMID:24953699

  12. Multijunction III-V solar cells - Recent and projected results

    NASA Astrophysics Data System (ADS)

    MacMillan, H. F.; Hamaker, H. C.; Virshup, G. F.; Werthen, J. G.

    The authors discuss Varian's strategy for developing high-efficiency multijunction cells. Recent cell performance data are reviewed and compared to computer modeling performance projections for two- and three-junction cascade cells. Results are presented for single-junction and multijunction monolithic structures fabricated with the AlGaAs-GaAs-InGaAs materials system grown by metal-organic chemical vapor deposition. The problems and progress for lattice-matched and lattice-mismatched structures and cell interconnects are discussed and assessed. It is concluded that the latest results are significant steps toward a demonstration of the viability of cascade cells. The hurdles to be overcome in an effort to achieve efficiencies above 30 percent are discussed.

  13. Multijunction III-V solar cells - Recent and projected results

    Microsoft Academic Search

    H. F. MacMillan; H. C. Hamaker; G. F. Virshup; J. G. Werthen

    1988-01-01

    The authors discuss Varian's strategy for developing high-efficiency multijunction cells. Recent cell performance data are reviewed and compared to computer modeling performance projections for two- and three-junction cascade cells. Results are presented for single-junction and multijunction monolithic structures fabricated with the AlGaAs-GaAs-InGaAs materials system grown by metal-organic chemical vapor deposition. The problems and progress for lattice-matched and lattice-mismatched structures and

  14. Alloy design and microstructure of a biomedical Co-Cr alloy

    Microsoft Academic Search

    Longquan Shi; D. O. Northwood; Zhengwang Cao

    1993-01-01

    Two wrought Co-Cr alloys for dental and surgical implant and equipment applications were designed and their microstructures and hot workability determined and compared to a current dental alloy SC-H. The chemical composition of the alloys was selected with regard to the general requirements for biomedical alloys and the general principles of alloying theory. A phase-control law originally developed for nickel-base

  15. Alloy rotary kilns for hazardous waste disposal

    Microsoft Academic Search

    J. V. Del Bene; J. K. Shah; E. F. Colburn

    1987-01-01

    The major conclusions of the study of rotary kilns for processing abrasive, energetic or corrosive hazardous wastes are: Alloy kilns are preferable to smaller refractory lined kilns for abrasive and\\/or explosive feed materials. Alloy construction and bolted sections make alloy kilns transportable; a pyrolysis operating mode can reduce the equipment size for wastes with a high energy release rate. However,

  16. Friction stir welding of aluminum alloys

    Microsoft Academic Search

    Fu Zhi-hong; He Di-qiu; Wang Hong

    2004-01-01

    Friction stir welding (FSW), a new solid-state welding technology invited in the early 1990s, enables us weld aluminum alloys\\u000a and titanium alloys etc. The processing of FSW, the microstructure in FSW alloys and the factors influencing weld quality\\u000a are introduced. The complex factors affecting the properties are researched.

  17. Development of zirconium alloys. Part II

    Microsoft Academic Search

    A. D. Schwope; W. Chubb

    1952-01-01

    A number of alloys of zirconium have been investigated as part of a program aimed at improving the high-temperature tensile and creep strength of zirconium. These alloys include aluminum, beryllium, lead, magnesium, molybdenum, niobium, tantalum, tin, titanium, tungsten, vanadium, and zinc, binary and ternary alloys. The data indicate that aluminum, lead, molybdenum niobium, tin, titanium, tungsten, and vanadium can be

  18. The response of shape memory alloy composites

    Microsoft Academic Search

    Jacob Aboudi

    1997-01-01

    A microstructural model that couples the local and global effects is employed to analyse the behavior of composite materials with shape memory alloy fibers. Both metallic matrices and resin matrix composites with embedded shape memory alloy fibers are considered. Since shape memory alloys form fibers with large diameter, this model is particularly suitable for the analysis of this type of

  19. Neutron Yields from Americium-Beryllium Alloys

    Microsoft Academic Search

    O. J. C. Runnalls; R. R. Boucher

    1955-01-01

    THE neutron yields from two americium - beryllium alloys have been measured. The alloys were prepared by the reduction of americium trifluoride with powdered beryllium metal in vacuum, according to the reaction: The beryllium fluoride readily distilled, leaving a fluoride-free alloy.

  20. Improved thermal treatment of aluminum alloy 7075

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.

    1968-01-01

    Newly developed tempering treatment considerably increases the corrosion resistance of 7075-T6 alloy and concomitantly preserves its yield strength. The results of tests on samples of the alloy subjected to the above treatments show that when the overaging period is 12 hours /at 325 degrees F/, the alloy exhibits a yield strength of 73,000 psi.

  1. INVESTIGATION OF TANTALUM AND ITS ALLOYS

    Microsoft Academic Search

    F. F. Schmidt; E. S. Bartlett; H. R. Ogden

    1963-01-01

    Minor (1 to 2%) reactive metal (Zr, Hf) additions to Ta-W-- Mo alloys ; effect pronounced strengthening at 1925 deg C with minimal degradation of low-; temperature alloy behavior. Additions of carbon to alloys containibg reactive ; metals degrade both 1925 deg C strength and low-temperature behavior; however, ; ZrC dispersions exhibit pronounced strengthening at lower temperatures (1480 deg ;

  2. High strength uranium-tungsten alloys

    DOEpatents

    Dunn, Paul S. (Santa Fe, NM); Sheinberg, Haskell (Los Alamos, NM); Hogan, Billy M. (Los Alamos, NM); Lewis, Homer D. (Bayfield, CO); Dickinson, James M. (Los Alamos, NM)

    1991-01-01

    Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

  3. High strength uranium-tungsten alloy process

    DOEpatents

    Dunn, Paul S. (Santa Fe, NM); Sheinberg, Haskell (Los Alamos, NM); Hogan, Billy M. (Los Alamos, NM); Lewis, Homer D. (Bayfield, CO); Dickinson, James M. (Los Alamos, NM)

    1990-01-01

    Alloys of uranium and tungsten and a method for making the alloys. The amount of tungsten present in the alloys is from about 4 wt % to about 35 wt %. Tungsten particles are dispersed throughout the uranium and a small amount of tungsten is dissolved in the uranium.

  4. Biocompatibility of dental casting alloys.

    PubMed

    Geurtsen, Werner

    2002-01-01

    Most cast dental restorations are made from alloys or commercially pure titanium (cpTi). Many orthodontic appliances are also fabricated from metallic materials. It has been documented in vitro and in vivo that metallic dental devices release metal ions, mainly due to corrosion. Those metallic components may be locally and systemically distributed and could play a role in the etiology of oral and systemic pathological conditions. The quality and quantity of the released cations depend upon the type of alloy and various corrosion parameters. No general correlation has been observed between alloy nobility and corrosion. However, it has been documented that some Ni-based alloys, such as beryllium-containing Ni alloys, exhibit increased corrosion, specifically at low pH. Further, microparticles are abraded from metallic restorations due to wear. In sufficient quantities, released metal ions-particularly Cu, Ni, Be, and abraded microparticles-can also induce inflammation of the adjacent periodontal tissues and the oral mucosa. While there is also some in vitro evidence that the immune response can be altered by various metal ions, the role of these ions in oral inflammatory diseases such as gingivitis and periodontitis is unknown. Allergic reactions due to metallic dental restorations have been documented. Ni has especially been identified as being highly allergenic. Interestingly, from 34% to 65.5% of the patients who are allergic to Ni are also allergic to Pd. Further, Pd allergy always occurrs with Ni sensitivity. In contrast, no study has been published which supports the hypothesis that dental metallic materials are mutagenic/genotoxic or might be a carcinogenic hazard to man. Taken together, very contradictory data have been documented regarding the local and systemic effects of dental casting alloys and metallic ions released from them. Therefore, it is of critical importance to elucidate the release of cations from metallic dental restorations in the oral environment and to determine the biological interactions of released metal components with oral and systemic tissues. PMID:12097239

  5. Ballistic transport in semiconductor alloys

    Microsoft Academic Search

    Srinivasan Krishnamurthy; M. A. Berding; A. Sher; A.-B. Chen

    1988-01-01

    The electronic structure of semiconductor compounds GaAs, InAs, and InP and alloys Ga0.5In0.5As, Ga0.7Al0.3As, and InP0.5As0.5, obtained in the coherent potential approximation, is used to calculate the group velocity and velocity relaxation time limited by longitudinal optical phonons, alloy disorder, and ionized impurities as a function of electron energy at 300 K. The nonparabolic nature of the band structure is

  6. Imparting passivity to vapor deposited magnesium alloys

    NASA Astrophysics Data System (ADS)

    Wolfe, Ryan C.

    Magnesium has the lowest density of all structural metals. Utilization of low density materials is advantageous from a design standpoint, because lower weight translates into improved performance of engineered products (i.e., notebook computers are more portable, vehicles achieve better gas mileage, and aircraft can carry more payload). Despite their low density and high strength to weight ratio, however, the widespread implementation of magnesium alloys is currently hindered by their relatively poor corrosion resistance. The objective of this research dissertation is to develop a scientific basis for the creation of a corrosion resistant magnesium alloy. The corrosion resistance of magnesium alloys is affected by several interrelated factors. Among these are alloying, microstructure, impurities, galvanic corrosion effects, and service conditions, among others. Alloying and modification of the microstructure are primary approaches to controlling corrosion. Furthermore, nonequilibrium alloying of magnesium via physical vapor deposition allows for the formation of single-phase magnesium alloys with supersaturated concentrations of passivity-enhancing elements. The microstructure and surface morphology is also modifiable during physical vapor deposition through the variation of evaporation power, pressure, temperature, ion bombardment, and the source-to-substrate distance. Aluminum, titanium, yttrium, and zirconium were initially chosen as candidates likely to impart passivity on vapor deposited magnesium alloys. Prior to this research, alloys of this type have never before been produced, much less studied. All of these metals were observed to afford some degree of corrosion resistance to magnesium. Due to the especially promising results from nonequilibrium alloying of magnesium with yttrium and titanium, the ternary magnesium-yttrium-titanium system was investigated in depth. While all of the alloys are lustrous, surface morphology is observed under the scanning electron microscope. The corrosion rate of the nonequilibrium sputtered alloys, as determined by polarization resistance, is significantly reduced compared to the most corrosion resistant commercial magnesium alloys. The open circuit potentials of the sputter deposited alloys are significantly more noble compared to commercial, equilibrium phase magnesium alloys. Galvanic corrosion susceptibility has also been considerably reduced. Nonequilibrium magnesium-yttrium-titanium alloys have been shown to achieve passivity autonomously by alteration of the composition chemistry of the surface oxide/hydroxide layer. Self-healing properties are also evident, as corrosion propagation can be arrested after initial pitting of the material. A clear relationship exists between the corrosion resistance of sputter vapor deposited magnesium alloys and the amount of ion bombardment incurred by the alloy during deposition. Argon pressure, the distance between the source and the substrate, and alloy morphology play important roles in determining the ability of the alloy to develop a passive film. Thermal effects, both during and after alloy deposition, alter the stress state of the alloys, precipitation of second phases, and the mechanical stability of the passive film. An optimal thermal treatment has been developed in order to maximize the corrosion resistance of the magnesium-yttrium-titanium alloys. The significance of the results includes the acquisition of electrochemical data for these novel materials, as well as expanding the utilization of magnesium alloys by the improvement in their corrosion resistance. The magnesium alloys developed in this work are more corrosion resistant than any commercial magnesium alloy. Structural components comprised of these alloys would therefore exhibit unprecedented corrosion performance. Coatings of these alloys on magnesium components would provide a corrosion resistant yet galvanically-compatible coating. The broad impact of these contributions is that these new low-density, corrosion resistant magnesium alloys can be used to produce engine

  7. Rapidly solidified alloys and their mechanical and magnetic properties

    Microsoft Academic Search

    B. C. Giessen; D. E. Polk; A. I. Taub

    1986-01-01

    This book is organized under the following headings: Processing; Amorphous Alloys Formation; Amorphous Alloys-Relaxation and Phase Transformation; Amorphous Alloys-Consolidation, Mechanical, and Chemical Properties; Amorphous Alloys-Magnetic Properties; Crystalline Magnetic Materials; Quasicrystals; Microstructure and Properties of Crystalline RSP Alloys-Light Metals: Aluminum, Magnesium, Titanium; Microstructure and Properties of Crystalline RSP Alloys-Nickel, Iron and Cobalt Alloysl; Microstructure and Properties of Crystallilne RSP Alloys-Other Systems.

  8. Creep Behavior of Hydrogenated Zirconium Alloys

    NASA Astrophysics Data System (ADS)

    Sarkar, A.; Boopathy, K.; Eapen, J.; Murty, K. L.

    2014-10-01

    Zirconium (Zr) alloys are the primary structural materials of most water reactors. Creep is considered to be one of the important degradation mechanisms of Zr alloys during reactor operating and repository conditions. Zr alloys pick up hydrogen (H2) during their service from the coolant water. Hydrogen can be present in solid solution or precipitated hydride form in Zr alloys depending upon the temperature and concentration. This study reviews the effect of hydrogen on creep behavior of Zr alloys used in the water reactors.

  9. Liquid metal ion source and alloy

    DOEpatents

    Clark, Jr., William M. (Thousand Oaks, CA); Utlaut, Mark W. (Saugus, CA); Behrens, Robert G. (Los Alamos, NM); Szklarz, Eugene G. (Los Alamos, NM); Storms, Edmund K. (Los Alamos, NM); Santandrea, Robert P. (Santa Fe, NM); Swanson, Lynwood W. (McMinnville, OR)

    1988-10-04

    A liquid metal ion source and alloy, wherein the species to be emitted from the ion source is contained in a congruently vaporizing alloy. In one embodiment, the liquid metal ion source acts as a source of arsenic, and in a source alloy the arsenic is combined with palladium, preferably in a liquid alloy having a range of compositions from about 24 to about 33 atomic percent arsenic. Such an alloy may be readily prepared by a combustion synthesis technique. Liquid metal ion sources thus prepared produce arsenic ions for implantation, have long lifetimes, and are highly stable in operation.

  10. Stress corrosion of high strength aluminum alloys.

    NASA Technical Reports Server (NTRS)

    Cocks, F. H.; Brummer, S. B.

    1972-01-01

    An investigation has been carried out to examine the relationship of the observed chemical and mechanical properties of Al-Cu and Al-Zn-Mg alloys to the stress corrosion mechanisms which dominate in each case. Two high purity alloys and analogous commercial alloys were selected. Fundamental differences between the behavior of Al-Cu and of Al-Zn-Mg alloys were observed. These differences in the corrosion behavior of the two types of alloys are augmented by substantial differences in their mechanical behavior. The relative cleavage energy of the grain boundaries is of particular importance.

  11. High-alloy materials for offshore applications

    SciTech Connect

    Lemke, T.F.; Harris, J.A.

    1983-05-01

    High-alloy materials possessing good corrosion resistance in hot, sour brines are being seriously considered for offshore applications. These alloys are available in a wide range of strength levels which can be attained by the methods of cold working or precipitation hardening. Results of testing INCONEL alloys 625 and 718 and INCOLOY alloys 825 and 925 for resistance to general corrosion, hydrogen embrittlement, and stress-corrosion cracking (SCC) are presented. This paper also contrasts the range of mechanical properties available in precipitation-hardened materials with properties of cold-worked alloys.

  12. Environmental fatigue in aluminum-lithium alloys

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.

    1992-01-01

    Aluminum-lithium alloys exhibit similar environmental fatigue crack growth characteristics compared to conventional 2000 series alloys and are more resistant to environmental fatigue compared to 7000 series alloys. The superior fatigue crack growth behavior of Al-Li alloys 2090, 2091, 8090, and 8091 is due to crack closure caused by tortuous crack path morphology and crack surface corrosion products. At high R and reduced closure, chemical environment effects are pronounced resulting in accelerated near threshold da/dN. The beneficial effects of crack closure are minimized for small cracks resulting in rapid growth rates. Limited data suggest that the 'chemically small crack' effect, observed in other alloy system, is not pronounced in Al-Li alloys. Modeling of environmental fatigue in Al-Li-Cu alloys related accelerated fatigue crack growth in moist air and salt water to hydrogen embrittlement.

  13. [Fatigue properties of dental alloys. 12% Au-Pd-Ag alloy and type III gold alloy].

    PubMed

    Kato, H

    1989-12-01

    Usually the mechanical properties of dental alloys are determined from the values obtained through static tests of their tensile strength, hardness, etc. Generally, high tensile strength and ductility are preferred. However, when small stresses within proportional limits are applied repeatedly (even though not amounting to destructive forces in static tests), they may cause rupture in the alloy or, at least, cause it to lose its original mechanical properties. This phenomenon is called metal fatigue. It is estimated that the intraoral stress loads received by dental restorations during mastication or during insertion and removal of appliances are repeated more than 3 x 10(5) times/year. From this standpoint, it may be more appropriate to estimate the fracture strength of such dental alloys based on the fatigue properties of the restorative materials used for clasps, bars, and fixed bridges. For this reason, it is necessary to obtain data through fatigue tests on the fatigue strength and the fatigue endurance limits of dental alloys, and it is important to find a correlation between these data and the static data on tensile strengths and ductility obtained by tensile tests. Two alloys are used in these experiments. Both wrought specimens and cast specimens of 12% Au-Pd-Ag and Type III gold alloy were prepared for the fatigue tests. The size of the rectangular wrought specimens was 3 x 4 x 110 mm. The 12% Au-Pd-Ag alloy was heated to 800 degrees C for 15 minutes, quenched, and reheated to 400 degrees C for 20 minutes and quenched again according to the manufacturer's instructions for heat treatment. The Type III gold alloy was heated to 700 degrees C for 10 minutes, quenched, and reheated to 350 degrees C for 20 minutes and quenched again. The cylindrical cast specimens were 60 mm long and 2 mm in diameter. They were invested by conventional methods and cast in a centrifugal casting machine, Thermotrol Model 2500. The four point bending test for the wrought specimen was performed with a Universal Fatigue testing machine, Shimazu UF-15 at a stress amplitude rate of 30 Hz. The cylindrical cast specimens were tested in cyclic tension in a Hydraulic IC Servo Machine, Instron Model 8501 at a gauge length of 25 mm and a stress amplitude of 10 Hz. The tensile tests for both wrought and cast specimens were performed with a Universal Testing Machine, Instron Model 1125 and measured at a cross-head speed of 1 mm/min.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2489466

  14. Zirconium alloy heat treatment process

    Microsoft Academic Search

    Urquhart

    1982-01-01

    Zirconium-base alloy channels, fuel cladding tubes, and other nuclear reactor structural components having unique resistance to accelerated pustular corrosion in a boiling water reactor environment are produced by a sequence of heat treatments causing segregation of intermetallic particulate precipitate phase in two dimensional arrays of particles of diameter from 100 to 400 angstroms located along grain boundaries and sub-grain boundaries

  15. Recent developments in light alloys

    NASA Technical Reports Server (NTRS)

    Woodward, R W

    1920-01-01

    This report is intended to cover the progress that has been made in both the manufacture and utility of light alloys in the United States since the first part of 1919. Duralumin is extensively discussed both as to manufacture and durability.

  16. Alcoa: the Alloy constraint analyzer

    Microsoft Academic Search

    Daniel Jackson; Ian Schechter; Ilya Shlyakhter

    2000-01-01

    Alcoa is a tool for analyzing object models. It has a range of uses. At one end, it can act as a support tool for object model diagrams, checking for consistency of multiplicities and generating sample snapshots. At the other end, it embodies a lightweight formal method in which subtle properties of behaviour can be investigated. Alcoa's input language, Alloy,

  17. Alcoa: the alloy constraint analyzer

    Microsoft Academic Search

    Daniel Jackson; Ian Schechter; Hya Shlyahter

    2000-01-01

    Alcoa is a tool for analyzing object models. It has a range of uses. At one end, it can act as a support tool for object model diagrams, checking for consistency of multiplicities and generating sample snapshots. At the other end, it embodies a lightweight formal method in which subtle properties of behaviour can be investigated.Alcoa's input language, Alloy, is

  18. Dispersion-strengthened chromium alloy

    NASA Technical Reports Server (NTRS)

    Blocker, J. M., Jr.; Veigel, N. D.

    1972-01-01

    Finely divided powder mixture produced by vapor deposition of CR on small ThO2 particles was hot pressed or pressure bonded. Resulting alloy has lower ductile-to-brittle transition temperature than pure chromium, and high strength and oxidation resistance at elevated temperatures, both in as-rolled condition and after annealing.

  19. Heusler alloys: Tuning exchange bias

    NASA Astrophysics Data System (ADS)

    Nordblad, Per

    2015-07-01

    Exchange bias is a magnetic phenomenon that has facilitated the ever-increasing storage density of magnetic recording systems. The finding of high tunable exchange bias in certain Heusler alloys indicates new routes for the design of rare-earth-free hard magnetic materials.

  20. Phase structure of electrodeposited alloys

    Microsoft Academic Search

    P. L. Cavallotti; L. Nobili; A. Vicenzo

    2005-01-01

    By electrodeposition it is possible to obtain alloy phases of metastable structure; these phases may be different from those reported for metallurgical equilibrium conditions or may have different compositions for the solubility limits, in some cases with very important enlargement. Typical cases are examined, discussing published results and presenting new findings. To understand the general behaviour, free energy versus composition