Sample records for ga ky ms

  1. ?? / Kagaku / ?? /Ky?ri: Science

    E-Print Network [OSTI]

    Tsukahara, T?go

    2012-01-01T23:59:59.000Z

    question when considering science and technology in Japanese?? /Kagaku / ?? /Ky?ri: Science Tsukahara T?go Translationto incorporate and develop science and technology from the

  2. MS Exam, Fall 2012, Solid State Electronic Devices (ECE 230A-B) 1. III-V compound semiconductor GaAs has two families of cleavage planes (110) and

    E-Print Network [OSTI]

    Wang, Deli

    MS Exam, Fall 2012, Solid State Electronic Devices (ECE 230A-B) ECE230A: 1. III-V compound of GaAs crystal. 1 #12;MS Exam, Fall 2012, Solid State Electronic Devices (ECE 230A-B) ECE 230B: Assume silicon, room temperature, complete ionization. 1. For an abrupt n+-p diode in Si, the n+ doping is 1020

  3. West KY Regional Middle School Science Bowl | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradley Nickell DirectorThe& FederalPleasePhotoWest KY Regional

  4. Fluidic Optics George M. Whitesides* and Sindy K.Y. Tang

    E-Print Network [OSTI]

    Prentiss, Mara

    Fluidic Optics George M. Whitesides* and Sindy K.Y. Tang Department of Chemistry and Chemical Biology, Harvard University 12 Oxford St., Cambridge, MA 02138 ABSTRACT Fluidic optics is a new class of optical system with real-time tunability and reconfigurability enabled by the introduction of fluidic

  5. Beta decay of Ga-62 

    E-Print Network [OSTI]

    Hyman, BC; Iacob, VE; Azhari, A.; Gagliardi, Carl A.; Hardy, John C.; Mayes, VE; Neilson, RG; Sanchez-Vega, M.; Tang, X.; Trache, L.; Tribble, Robert E.

    2003-01-01T23:59:59.000Z

    We report a study of the beta decay of Ga-62, whose dominant branch is a superallowed 0(+)-->0(+) transition to the ground state of Zn-62. We find the total half-life to be 115.84+/-0.25 ms. This is the first time that the Ga-62 half-life has been...

  6. MS Detectors

    SciTech Connect (OSTI)

    Koppenaal, David W.; Barinaga, Charles J.; Denton, M Bonner B.; Sperline, Roger P.; Hieftje, Gary M.; Schilling, G. D.; Andrade, Francisco J.; Barnes IV., James H.

    2005-11-01T23:59:59.000Z

    Good eyesight is often taken for granted, a situation that everyone appreciates once vision begins to fade with age. New eyeglasses or contact lenses are traditional ways to improve vision, but recent new technology, i.e. LASIK laser eye surgery, provides a new and exciting means for marked vision restoration and improvement. In mass spectrometry, detectors are the 'eyes' of the MS instrument. These 'eyes' have also been taken for granted. New detectors and new technologies are likewise needed to correct, improve, and extend ion detection and hence, our 'chemical vision'. The purpose of this report is to review and assess current MS detector technology and to provide a glimpse towards future detector technologies. It is hoped that the report will also serve to motivate interest, prompt ideas, and inspire new visions for ion detection research.

  7. Finding the largest low-rank clusters with Ky Fan 2-k-norm and l1-norm

    E-Print Network [OSTI]

    Xuan Vinh Doan

    2014-03-24T23:59:59.000Z

    Mar 24, 2014 ... Abstract: We propose a convex optimization formulation with the Ky Fan 2-k-norm and l1-norm to fi nd k largest approximately rank-one ...

  8. Fractal Location and Anomalous Diffusion Dynamics for Oil Wells from the KY Geological Survey

    E-Print Network [OSTI]

    Andrew, Keith; Andrew, Kevin A

    2009-01-01T23:59:59.000Z

    Utilizing data available from the Kentucky Geonet (KYGeonet.ky.gov) the fossil fuel mining locations created by the Kentucky Geological Survey geo-locating oil and gas wells are mapped using ESRI ArcGIS in Kentucky single plain 1602 ft projection. This data was then exported into a spreadsheet showing latitude and longitude for each point to be used for modeling at different scales to determine the fractal dimension of the set. Following the porosity and diffusivity studies of Tarafdar and Roy1 we extract fractal dimensions of the fossil fuel mining locations and search for evidence of scaling laws for the set of deposits. The Levy index is used to determine a match to a statistical mechanically motivated generalized probability function for the wells. This probability distribution corresponds to a solution of a dynamical anomalous diffusion equation of fractional order that describes the Levy paths which can be solved in the diffusion limit by the Fox H function ansatz.

  9. Research results from the Ashland Exploration, Inc., Ford Motor Company 80 (COOP 2) well, Pike County, KY. Topical report, October 1991-November 1992

    SciTech Connect (OSTI)

    Frantz, J.H.; Lancaster, D.E.

    1993-04-01T23:59:59.000Z

    The report summarizes the work performed on the Ashland Exploration, Inc. (AEI) Ford Motor Company 80 (COOP 2) well in Pike County, KY. The COOP 2 was the second well in a three-well research project being conducted by GRI in eastern Kentucky targeting both the Devonian Shales and the Berea Sand; the FMC 80 focused on the Berea. The primary objective of the research was to use and transfer technologies developed in GRI`s Tight Gas Sands and Gas Shales programs to evaluate the Berea in Pike Co., KY.

  10. Improved InGaN/GaN light-emitting diodes with a p-GaN/n-GaN/p-GaN/n-GaN/p-GaN current-

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Improved InGaN/GaN light-emitting diodes with a p-GaN/n-GaN/p-GaN/n-GaN/p-GaN current- spreading experimental and theoretical studies on the InGaN/GaN light-emitting diodes (LEDs) with optical output power and external quantum efficiency (EQE) levels substantially enhanced by incorporating p-GaN/n-GaN/p-GaN/n-GaN/p-GaN

  11. ICP-MS Workshop

    SciTech Connect (OSTI)

    Carman, April J.; Eiden, Gregory C.

    2014-11-01T23:59:59.000Z

    This is a short document that explains the materials that will be transmitted to LLNL and DNN HQ regarding the ICP-MS Workshop held at PNNL June 17-19th. The goal of the information is to pass on to LLNL information regarding the planning and preparations for the Workshop at PNNL in preparation of the SIMS workshop at LLNL.

  12. Prof Dr Mr Mrs Ms Prof Dr Mr Mrs Ms

    E-Print Network [OSTI]

    Xu, Jianliang

    Prof Dr Mr Mrs Ms Prof Dr Mr Mrs Ms Standard Room Request Payment Card No Expiry Date Contact or a 1-night applicable room charge will be levied as cancellation charge. * Daily rate will be subject

  13. 5""reuniondu GroupeMarocaindu Permien et du Trias El Jadida,26-29Avril2006. Maroc The first 200 ky of the Early Jurassic in eastern North America and Morocco

    E-Print Network [OSTI]

    Olsen, Paul E.

    5""Ã?reuniondu GroupeMarocaindu Permien et du Trias El Jadida,26-29Avril2006. Maroc The first 200 ky, 26-29 Avril2006, Maroc likewise of low taxonomic diversity at the family level consisting almost

  14. On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N-GaN built-in junctions in the n-GaN layer for

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    On the effect of N-GaN/P-GaN/N-GaN/P-GaN/N- GaN built-in junctions in the n-GaN layer for InGaN/GaN: N-GaN/P-GaN/N-GaN/P-GaN/N-GaN (NPNPN-GaN) junctions embedded between the n-GaN region and multiple the performance of InGaN/GaN light emitting diodes (LEDs) in this work. In the proposed architecture, each thin P-GaN

  15. M.S. Physics Program M.S. in Physics

    E-Print Network [OSTI]

    Hemmers, Oliver

    M.S. Physics Program M.S. in Physics Department(s) Physics and Astronomy College Sciences 1 for later reference. 1. understanding of a variety of fields of physics at the graduate level 2. performance of a physics research project suitable for a masters thesis 3. ability to communicate scientific research

  16. Microsoft Word - 2014 DOE Science Bowl MS results with photos

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    FOR IMMEDIATE RELEASE Buz Smith (270) 441-6821 Feb. 28, 2014 Robert.Smith@lex.doe.gov Lone Oak Middle School Finishes 1-2 in DOE Regional Science Bowl PADUCAH, KY - Teams from...

  17. METLIN: MS/MS metabolite data from the MAGGIE Project

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    METLIN is a metabolite database for metabolomics containing over 50,000 structures, it also represents a data management system designed to assist in a broad array of metabolite research and metabolite identification by providing public access to its repository of current and comprehensive MS/MS metabolite data. An annotated list of known metabolites and their mass, chemical formula, and structure are available on the METLIN website. Each metabolite is conveniently linked to outside resources such as the the Kyoto Encyclopedia of Genes and Genomes (KEGG) for further reference and inquiry. MS/MS data is also available on many of the metabolites. The list is expanding continuously as more metabolite information is being deposited and discovered. [from http://metlin.scripps.edu/] Metlin is a component of the MAGGIE Project. MAGGIE is funded by the DOE Genomics: GTL and is an acronym for "Molecular Assemblies, Genes, and Genomics Integrated Efficiently."

  18. ECE 230A/B AP/EDM (Grad) MS Comprehensive Exam FA10

    E-Print Network [OSTI]

    Wang, Deli

    ECE 230A/B ­ AP/EDM (Grad) MS Comprehensive Exam FA10 Problem 1 For the 1-D Ga (everything else unchanged). (d) Replace the Si base with a uniform SiGe base of bandgap 0.1 eV smaller than that of Si (everything else unchanged). #12;

  19. Ms. Maria Galanti Site Coordinator

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Office 2195 Front Street Logan, Ohio 43138 Dear Ms. Galanti: TRANSMITTAL OF Dl CONSTRUCTION COMPLETION REPORT FOR PHASES I AND II OF THE REMOVAL OF THE X-760 CHEMICAL...

  20. KY_50mwind

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    WPC DistributionInformation: ResourceDescription: Downloadable Data StandardOrderProcess: DigitalForm: DigitalTransferInformation: TransferSize: 0.395...

  1. Graphene/GaN diodes for ultraviolet and visible photodetectors

    SciTech Connect (OSTI)

    Lin, Fang; Chen, Shao-Wen; Meng, Jie; Tse, Geoffrey; Fu, Xue-Wen; Xu, Fu-Jun [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Shen, Bo; Liao, Zhi-Min, E-mail: liaozm@pku.edu.cn, E-mail: yudp@pku.edu.cn; Yu, Da-Peng, E-mail: liaozm@pku.edu.cn, E-mail: yudp@pku.edu.cn [State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China)

    2014-08-18T23:59:59.000Z

    The Schottky diodes based on graphene/GaN interface are fabricated and demonstrated for the dual-wavelength photodetection of ultraviolet (UV) and green lights. The physical mechanisms of the photoelectric response of the diodes with different light wavelengths are different. For UV illumination, the photo-generated carriers lower the Schottky barrier and increase the photocurrent. For green light illumination, as the photon energy is smaller than the bandgap of GaN, the hot electrons excited in graphene via internal photoemission are responsible for the photoelectric response. Using graphene as a transparent electrode, the diodes show a ?mS photoresponse, providing an alternative route toward multi-wavelength photodetectors.

  2. Ms. Nancy Slach Department of

    E-Print Network [OSTI]

    /Certificate, Orthodon- tics, 1948 UI Alumni Service Award Ms. Penni Ryan Alumni Relations and Con- tinuing Dental Education 2009 Regents Staff Excellence Award; President designate of the Association of Continuing Dental Education (2013). Dr. Jeffrey Murray Colleges of Medicine and Dentistry Research grant total: $1

  3. Advantages of the Blue InGaN/GaN Light-Emitting Diodes with an AlGaN/GaN/AlGaN Quantum Well Structured Electron Blocking Layer

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Advantages of the Blue InGaN/GaN Light-Emitting Diodes with an AlGaN/GaN/AlGaN Quantum Well ABSTRACT: InGaN/GaN light-emitting diodes (LEDs) with p-(AlGaN/GaN/AlGaN) quantum well structured electron. The proposed QWEBL LED structure, in which a p-GaN QW layer is inserted in the p-AlGaN electron blocking layer

  4. The role of the N*(1535) resonance and the pi^- p --> KY amplitudes in the OZI forbidden pi N --> phi N reaction

    E-Print Network [OSTI]

    M. Döring; E. Oset; B. S. Zou

    2008-07-11T23:59:59.000Z

    We study the pi N --> phi N reaction close to the phi N threshold within the chiral unitary approach, by combining the pi^- p --> K^+ Sigma^-, pi^- p --> K^0 Sigma^0 and pi^- p --> K^0 Lambda amplitudes with the coupling of the phi to the K components of the final states of these reactions via quantum loops. We obtain a good agreement with experiment when the dominant pi^- p --> K^0 Lambda amplitude is constrained with its experimental cross section. We also evaluate the coupling of the N*(1535) to phi N and find a moderate coupling as a consequence of partial cancellation of the large KY components of the N*(1535). We also show that the N*(1535) pole approximation is too small to reproduce the measured cross section for the pi N --> phi N reaction.

  5. Micromechanical resonators fabricated from lattice-matched and etch-selective GaAs/InGaP/GaAs heterostructures

    E-Print Network [OSTI]

    Micromechanical resonators fabricated from lattice-matched and etch-selective GaAs/InGaP September 2007 Utilizing lattice-matched GaAs/InGaP/GaAs heterostructures, clean micromechanical resonators are fabricated and characterized. The nearly perfect selectivity of GaAs/InGaP is demonstrated by realizing

  6. Ga nanoparticle-enhanced photoluminescence of GaAs

    SciTech Connect (OSTI)

    Kang, M.; Al-Heji, A. A.; Jeon, S.; Wu, J. H. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Lee, J.-E.; Saucer, T. W.; Zhao, L.; Sih, V. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States); Katzenstein, A. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Eckerd College, St. Petersburg, Florida 33711-4744 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

    2013-09-02T23:59:59.000Z

    We have examined the influence of surface Ga nanoparticles (NPs) on the enhancement of GaAs photoluminescence (PL) efficiency. We have utilized off-normal focused-ion-beam irradiation of GaAs surfaces to fabricate close-packed Ga NP arrays. The enhancement in PL efficiency is inversely proportional to the Ga NP diameter. The maximum PL enhancement occurs for the Ga NP diameter predicted to maximize the incident electromagnetic (EM) field enhancement. The PL enhancement is driven by the surface plasmon resonance (SPR)-induced enhancement of the incident EM field which overwhelms the SPR-induced suppression of the light emission.

  7. AlGaN/GaN-based power semiconductor switches

    E-Print Network [OSTI]

    Lu, Bin, Ph. D. Massachusetts Institute of Technology

    2013-01-01T23:59:59.000Z

    AlGaN/GaN-based high-electron-mobility transistors (HEMTs) have great potential for their use as high efficiency and high speed power semiconductor switches, thanks to their high breakdown electric field, mobility and ...

  8. GaAs/InGaP/AlGaAs quantum-well infrared photodetectors

    SciTech Connect (OSTI)

    Keshagupta, P.; Radpour, F. [Univ. of Cincinnati, OH (United States)

    1994-12-31T23:59:59.000Z

    In this paper, a new quantum-well infrared photodetector (QWIP) based on bound-to-miniband transitions in a GaAs/InGaP quantum well with GaAs/AlGaAs short superlattice barriers is presented and compared with the conventional GaAs/InGaP QWIPs. Results of the theoretical calculations of the detector parameters and the preliminary fabrication results of an embedded-well to miniband (EWTMB) GaAs/InGaP/AlGaAs quantum well/superlattice detector are presented. The advantages of the proposed design include improvement of the material quality, ability to adjust the peak wavelength in 8--12 {micro}m range, and in the lower dark current.

  9. ARM - Instrument - ptr-ms

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006Datastreamstwrcam40mgovInstrumentsmwr3c Documentation MWR3CgovInstrumentspgsgovInstrumentsptr-ms

  10. LA-5097-MS INFORMAL REPORT

    Office of Legacy Management (LM)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOn AprilA group currentBradleyTableSelling CorpNewCF INDUSTRIES,L? .-I I2 m.m 2L5097-MS

  11. Carrier spin relaxation in GaInNAsSb/GaNAsSb/GaAs quantum well

    SciTech Connect (OSTI)

    Asami, T.; Nosho, H.; Tackeuchi, A. [Department of Applied Physics, Waseda University, Shinjuku, Tokyo 169-8555 (Japan); Li, L. H.; Harmand, J. C. [Laboratory for Photonics and Nanostructures-CNRS, Site Alcatel de Marcoussis, Route de Nozay, 91460 Marcoussis (France); Lu, S. L. [Suzhou Institute of Nano-tech and Nano-bionics, CAS, Dushu, Lake Higher Education Town, Ruoshui Road 398, Suzhou Industrial Park, Suzhou 215125 (China)

    2011-12-23T23:59:59.000Z

    We have investigated the carrier spin relaxation in GaInNAsSb/GaNAsSb/GaAs quantum well (QW) by time-resolved photoluminescence (PL) measurement. The sample consists of an 8-nm-thick GaIn{sub 0.36}N{sub 0.006}AsSb{sub 0.015} well, 5-nm-thick GaN{sub 0.01}AsSb{sub 0.11} intermediate barriers and 100-nm-thick GaAs barriers grown by molecular beam epitaxy on a GaAs(100) substrate. The spin relaxation time and recombination lifetime at 10 K are measured to be 228 ps and 151 ps, respectively. As a reference, we have also obtained a spin relaxation time of 125 ps and a recombination lifetime of 63 ps for GaInNAs/GaNAs/GaAs QW. This result shows that crystal quality is slightly improved by adding Sb, although these short carrier lifetimes mainly originate from a nonradiative recombination. These spin relaxation times are longer than the 36 ps spin relaxation time of InGaAs/InP QWs and shorter than the 2 ns spin relaxation time of GaInNAs/GaAs QW.

  12. Compositionally-graded InGaAsInGaP alloys and GaAsSb alloys for metamorphic InP on GaAs

    E-Print Network [OSTI]

    Compositionally-graded InGaAs­InGaP alloys and GaAsSb alloys for metamorphic InP on GaAs Li Yang a of tandem graded layers of InGaAs and InGaP with compositional grading of the In concentration. This tandem

  13. Kentucky Department for Natural Resources and Environmental Protection permit application for air contaminant source: SRC-I demonstration plant, Newman, Kentucky. Supplement I. [Additional information on 38 items requested by KY/DNREP

    SciTech Connect (OSTI)

    Pearson, Jr., John F.

    1981-02-13T23:59:59.000Z

    In response to a letter from KY/DNREP, January 19, 1981, ICRC and DOE have prepared the enclosed supplement to the Kentucky Department for Natural Resources and Environmental Protection Permit Application for Air Contaminant Source for the SRC-I Demonstration Plant. Each of the 38 comments contained in the letter has been addressed in accordance with the discussions held in Frankfort on January 28, 1981, among representatives of KY/DNREP, EPA Region IV, US DOE, and ICRC. The questions raised involve requests for detailed information on the performance and reliability of proprietary equipment, back-up methods, monitoring plans for various pollutants, composition of wastes to flares, emissions estimates from particular operations, origin of baseline information, mathematical models, storage tanks, dusts, etc. (LTN)

  14. Low frequency noise in AlGaN/InGaN/GaN double heterostructure field effect transistors

    E-Print Network [OSTI]

    Pala, Nezih

    Torr and consisted of a 1.4 lm undoped GaN buffer layer on i-SiC substrate, * Corresponding authorLow frequency noise in AlGaN/InGaN/GaN double heterostructure field effect transistors N. Pala a November 2002 Abstract Low-frequency noise in AlGaN/InGaN/GaN double heterostructure field effect

  15. Polarization-engineered GaN/InGaN/GaN tunnel diodes

    E-Print Network [OSTI]

    Sriram Krishnamoorthy; Digbijoy N. Nath; Fatih Akyol; Pil Sung Park; Michele Esposto; Siddharth Rajan

    2010-08-24T23:59:59.000Z

    We report on the design and demonstration of polarization-engineered GaN/InGaN/GaN tunnel junction diodes with high current density and low tunneling turn-on voltage. Wentzel-Kramers-Brillouin (WKB) calculations were used to model and design tunnel junctions with narrow bandgap InGaN-based barrier layers. N-polar p-GaN/In0.33Ga0.67N/n-GaN heterostructure tunnel diodes were grown using molecular beam epitaxy. Efficient zero bias tunneling turn-on with a high current density of 118 A/cm2 at a reverse bias of 1V, reaching a maximum current density up to 9.2 kA/cm2 were obtained. These results represent the highest current density reported in III-nitride tunnel junctions, and demonstrate the potential of III-nitride tunnel devices for a broad range of optoelectronic and electronic applications.

  16. Violet to deep-ultraviolet InGaN/GaN and GaN/AlGaN quantum structures for UV electroabsorption modulators

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Violet to deep-ultraviolet InGaN/GaN and GaN/AlGaN quantum structures for UV electroabsorption In this paper, we present four GaN based polar quantum structures grown on c-plane embedded in p-i-n diode GaN/AlGaN quantum structures for operation in the deep-UV spectral region and the other three

  17. Entertainment Technology Center, CMU Internship Survey Results, Dec 2013, May 2014, and Dec 2014

    E-Print Network [OSTI]

    Matsuda, Noboru

    Developer Mount Pleasant SC Visionary Works LLC UX Designer, Game Programmer Washington DC VOCI Technology, NM, OK, TX 2 West: CA, HI, NV 16 Southeast: AL, AR, FL, GA, KY, LA, MS, NC, PR, SC, TN 1 Midwest: IA Emails 28 Faculty Contacts 22 Personal Network 17 Interviews Arranged by Career Services 9 Intern Search

  18. Entertainment Technology Center, CMU Post-Graduation Survey Results, Dec 2012, May 2013, and Aug 2013

    E-Print Network [OSTI]

    Matsuda, Noboru

    Alumni Contacts 13 ETC dlist email 11 Intern Search/Company Websites 9 Faculty Contacts 8 Interviews Southwest: AZ, NM, OK, TX 1 West: CA, HI, NV 40 Southeast: AL, AR, FL, GA, KY, LA, MS, NC, PR, SC, TN 3

  19. 2d-LC-MS/MS Method-ORNL Developed for Bacteriophage

    E-Print Network [OSTI]

    Sullivan, Matthew B.

    mass spectrometry (2d-LC-MS/MS) method was optimized for bacteriophage by Kristen Corrier undergraduate should be. 4. The mass spectrometer is run in data dependent mode, specific settings should be optimized

  20. Luminescence Efficiency of InGaN/GaN Quantum Wells on Bulk GaN Substrate M. Dworzak1

    E-Print Network [OSTI]

    Nabben, Reinhard

    Luminescence Efficiency of InGaN/GaN Quantum Wells on Bulk GaN Substrate M. Dworzak1 , T. Stempel1/37, 01-142 Warsaw, Poland ABSTRACT Time-integrated and time-resolved photoluminescence measurements on InGaN quantum wells grown by MOCVD on two different substrates (sapphire and GaN) show that the lumines- cence

  1. Analysis of InGaN light-emitting diodes with GaN-AlGaN and AlGaN-GaN composition-graded barriers

    SciTech Connect (OSTI)

    Yang, Yujue; Wang, Junxi; Li, Jinmin; Zeng, Yiping, E-mail: ypzeng@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2014-06-21T23:59:59.000Z

    The effects of InGaN-based light-emitting diodes (LEDs) with Al composition increasing and decreasing GaN-AlGaN barriers along the growth direction are studied numerically. Simulation results suggest that the LEDs with GaN-AlGaN composition-decreased barriers show more significant enhancement of light-output power and internal quantum efficiency than LEDs with composition-increasing GaN-AlGaN barriers when compared with the conventional LED with GaN barriers, due to the improvement in hole injection efficiency and electron blocking capability. Moreover, the optical performance is further improved by replacing GaN-AlGaN barriers with AlGaN-GaN barriers of the same Al composition-decreasing range, which are mainly attributed to the modified band diagrams. In addition, the major causes of the different efficiency droop behaviors for all the designed structures are explained by the electron leakage current and the different increase rates of hole concentration with injection current.

  2. Design and fabrication of InGaN/GaN heterojunction bipolar transistors for microwave power amplifiers

    E-Print Network [OSTI]

    Keogh, David Martin

    2006-01-01T23:59:59.000Z

    T. Henderson, “High- Speed InGaP/GaAs HBT’s Using a SimpleA typical AlGaAs/GaAs HBT or InGaP/GaAs HBT has the opposite

  3. Investigation of the GaN-on-GaAs interface for vertical power device applications

    SciTech Connect (OSTI)

    Möreke, Janina, E-mail: janina.moereke@bristol.ac.uk; Uren, Michael J.; Kuball, Martin [H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Novikov, Sergei V.; Foxon, C. Thomas [Department of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Hosseini Vajargah, Shahrzad; Wallis, David J.; Humphreys, Colin J. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Haigh, Sarah J. [Super STEM Laboratory, STFC Daresbury Campus, Keckwick Lane, Daresbury WA4 4AD (United Kingdom); School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Al-Khalidi, Abdullah; Wasige, Edward; Thayne, Iain [School of Engineering, University of Glasgow, Rankine Bldg, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)

    2014-07-07T23:59:59.000Z

    GaN layers were grown onto (111) GaAs by molecular beam epitaxy. Minimal band offset between the conduction bands for GaN and GaAs materials has been suggested in the literature raising the possibility of using GaN-on-GaAs for vertical power device applications. I-V and C-V measurements of the GaN/GaAs heterostructures however yielded a rectifying junction, even when both sides of the junction were heavily doped with an n-type dopant. Transmission electron microscopy analysis further confirmed the challenge in creating a GaN/GaAs Ohmic interface by showing a large density of dislocations in the GaN layer and suggesting roughening of the GaN/GaAs interface due to etching of the GaAs by the nitrogen plasma, diffusion of nitrogen or melting of Ga into the GaAs substrate.

  4. Ga NMR spectra and relaxation in wurtzite GaN M. Corti and A. Gabetta

    E-Print Network [OSTI]

    Svane, Axel Torstein

    69,71 Ga NMR spectra and relaxation in wurtzite GaN M. Corti and A. Gabetta Department of Physics properties of wurtzite GaN are studied by Ga nuclear magnetic resonance NMR in a GaN bulk crystal containing GaN is a wide band-gap semiconductor which crystallizes in the hexagonal wurtzite structure

  5. Cross-sectional Scanning Tunneling Microscopy and Spectroscopy of InGaP/GaAs Heterojunctions

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Cross-sectional Scanning Tunneling Microscopy and Spectroscopy of InGaP/GaAs Heterojunctions Y Abstract Compositionally abrupt InGaP/GaAs heterojunctions grown by gas-source molecular beam epitaxy have the InGaP layer show non-uniform In and Ga distribution. About 1.5 nm of transition region

  6. Role of Electrochemical Reactions in the Degradation Mechanisms of AlGaN/GaN HEMTs

    E-Print Network [OSTI]

    del Alamo, Jesús A.

    Role of Electrochemical Reactions in the Degradation Mechanisms of AlGaN/GaN HEMTs Feng Gao1, USA tpalacios@mit.edu; (617) 324-2395 Keywords: AlGaN/GaN HEMTs, reliability, moisture, electro-chemical reactions Abstract The nature of structural degradation in AlGaN/GaN high electron mobility transistors

  7. Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High

    E-Print Network [OSTI]

    Li, Yat

    Dopant-Free GaN/AlN/AlGaN Radial Nanowire Heterostructures as High Electron Mobility Transistors, 2006 ABSTRACT We report the rational synthesis of dopant-free GaN/AlN/AlGaN radial nanowire-organic chemical vapor deposition (MOCVD). Transmission electron microscopy (TEM) studies reveal that the GaN/ AlN/AlGaN

  8. Influence of GaAs surface termination on GaSb/GaAs quantum dot structure and band offsets

    SciTech Connect (OSTI)

    Zech, E. S.; Chang, A. S.; Martin, A. J.; Canniff, J. C.; Millunchick, J. M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Lin, Y. H. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)

    2013-08-19T23:59:59.000Z

    We have investigated the influence of GaAs surface termination on the nanoscale structure and band offsets of GaSb/GaAs quantum dots (QDs) grown by molecular-beam epitaxy. Transmission electron microscopy reveals both coherent and semi-coherent clusters, as well as misfit dislocations, independent of surface termination. Cross-sectional scanning tunneling microscopy and spectroscopy reveal clustered GaSb QDs with type I band offsets at the GaSb/GaAs interfaces. We discuss the relative influences of strain and QD clustering on the band offsets at GaSb/GaAs interfaces.

  9. Analysis of Thiodiglycol: Validation of Semi-Volatile Analysis by HPLC-MS/MS by EPA Method MS777

    SciTech Connect (OSTI)

    Owens, J; Koester, C

    2008-07-24T23:59:59.000Z

    The Environmental Protection Agency's (EPA) Region 5 Chicago Regional Laboratory (CRL) developed a method for the analysis of thiodiglycol, the breakdown product of the sulfur mustard HD, in water by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), titled Method EPA MS777 (hereafter referred to as EPA CRL SOP MS777). This draft standard operating procedure (SOP) was distributed to multiple EPA laboratories and to Lawrence Livermore National Laboratory, which was tasked to serve as a reference laboratory for EPA's Environmental Reference Laboratory Network (ERLN) and to develop and validate analytical procedures. The primary objective of this study was to verify the analytical procedures described in MS777 for analysis of thiodiglycol in aqueous samples. The gathered data from this study will be used to: (1) demonstrate analytical method performance; (2) generate quality control acceptance criteria; and (3) revise the SOP to provide a validated method that would be available for use during a homeland security event. The data contained in this report will be compiled, by EPA CRL, with data generated by other EPA Regional laboratories so that performance metrics of Method EPA MS777 can be determined.

  10. MS.BIOLOGY.THESIS ACADEMIC LEARNING PLAN

    E-Print Network [OSTI]

    O'Laughlin, Jay

    effectively to constructive feedback. Job Prospects for Biology Graduates MS in Biology Bioremediation Biotechnology Medical Research Industry Government Education Microbiology Health Professions Research Health Food Production Pollution Control Environmental Diagnostics Forestry Agriculture #12;APPENDIX B

  11. Energy Management Standards (EnMS)

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Management Standards (EnMS) Paul Scheihing U.S. DOE January, 2009 2 Why an Energy Management Standard? Most energy efficiency in industry is achieved through changes in how energy...

  12. Laser Ablation-ICP-MS Analysis of Dissected Tissue: A

    E-Print Network [OSTI]

    Hopkins, William A.

    Laser Ablation-ICP-MS Analysis of Dissected Tissue: A Conservation-Minded Approach to Assessing the animal. In this paper, we report on the application of laser ablation-ICP-MS (LA- ICP-MS) for sampling

  13. Sources of Technical Variability in Quantitative LC-MS Proteomics...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Sources of Technical Variability in Quantitative LC-MS Proteomics: Human Brain Tissue Sample Analysis. Sources of Technical Variability in Quantitative LC-MS Proteomics: Human...

  14. Electrospray Ionization Tandem Mass Spectrometry (ESI-MS/MS)-Based Shotgun Lipidomics

    SciTech Connect (OSTI)

    Mezengie, Giorgis I.

    2011-01-11T23:59:59.000Z

    In the past decade, many new strategies for mass spectrometry (MS)-based analyses of lipids have been developed. Lipidomics is one of the most promising research fields to emerge as a result of these advances in MS. Currently, mass spectrometric analysis of lipids involves two complementary approaches: direct infusion (shotgun lipidomics) and liquid chromatography coupled to MS. In this chapter, I will demonstrate the approach of shotgun lipidomics using electrospray ionization tandem MS for the analysis of lipid molecular species directly from crude biological extracts of tissue or fluids.

  15. Analysis of Ethanolamines: Validation of Semi-Volatile Analysis by HPLC-MS/MS by EPA Method MS888

    SciTech Connect (OSTI)

    Owens, J; Vu, A; Koester, C

    2008-10-08T23:59:59.000Z

    The Environmental Protection Agency's (EPA) Region 5 Chicago Regional Laboratory (CRL) developed a method titled 'Analysis of Diethanolamine, Triethanolamine, n-Methyldiethanolamine, and n-Ethyldiethanolamine in Water by Single Reaction Monitoring Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS): EPA Method MS888'. This draft standard operating procedure (SOP) was distributed to multiple EPA laboratories and to Lawrence Livermore National Laboratory, which was tasked to serve as a reference laboratory for EPA's Environmental Reference Laboratory Network (ERLN) and to develop and validate analytical procedures. The primary objective of this study was to validate and verify the analytical procedures described in 'EPA Method MS888' for analysis of the listed ethanolamines in aqueous samples. The gathered data from this validation study will be used to: (1) demonstrate analytical method performance; (2) generate quality control acceptance criteria; and (3) revise the SOP to provide a validated method that would be available for use during a homeland security event. The data contained in this report will be compiled, by EPA CRL, with data generated by other EPA Regional laboratories so that performance metrics of 'EPA Method MS888' can be determined.

  16. Analysis of Carbamate Pesticides: Validation of Semi-Volatile Analysis by HPLC-MS/MS by EPA Method MS666

    SciTech Connect (OSTI)

    Owens, J; Koester, C

    2008-05-14T23:59:59.000Z

    The Environmental Protection Agency's (EPA) Region 5 Chicago Regional Laboratory (CRL) developed a method for analysis of aldicarb, bromadiolone, carbofuran, oxamyl, and methomyl in water by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), titled Method EPA MS666. This draft standard operating procedure (SOP) was distributed to multiple EPA laboratories and to Lawrence Livermore National Laboratory, which was tasked to serve as a reference laboratory for EPA's Environmental Reference Laboratory Network (ERLN) and to develop and validate analytical procedures. The primary objective of this study was to validate and verify the analytical procedures described in MS666 for analysis of carbamate pesticides in aqueous samples. The gathered data from this validation study will be used to: (1) demonstrate analytical method performance; (2) generate quality control acceptance criteria; and (3) revise the SOP to provide a validated method that would be available for use during a homeland security event. The data contained in this report will be compiled, by EPA CRL, with data generated by other EPA Regional laboratories so that performance metrics of Method EPA MS666 can be determined.

  17. Multiple-band-edge quantum-well intermixing in the InGaAs/InGaAsP/InGaP material system

    E-Print Network [OSTI]

    Coldren, Larry A.

    Multiple-band-edge quantum-well intermixing in the InGaAs/InGaAsP/InGaP material system Erik J InGaAs/InGaAsP/InGaP material system. © 2005 American Institute of Physics. DOI: 10 of achieving QWI in such active regions.3,4 However, InGaAs/InGaAsP/InGaP-based de- vices offer numerous

  18. GaInNAs laser gain

    SciTech Connect (OSTI)

    CHOW,WENG W.; JONES,ERIC D.; MODINE,NORMAND A.; KURTZ,STEVEN R.; ALLERMAN,ANDREW A.

    2000-05-23T23:59:59.000Z

    The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.

  19. Red emitting photonic devices using InGaP/InGaAlP material system

    E-Print Network [OSTI]

    Kangude, Yamini

    2005-01-01T23:59:59.000Z

    In this thesis, two red emitting photonic devices are presented using the InGaP/InGaAlP material system. InGaP/InGaAlP material system provides large flexibility in the band gap energy while being lattice matched to GaAs ...

  20. AlGaAs/InGaAs/AlGaAs Double Barrier

    E-Print Network [OSTI]

    Perera, A. G. Unil

    -state Er. Tunneling Quantum Dot Sensors for Multi-band Infrared and Terahertz Radiation Detection G radiation detection are demonstrated. In T-QDIP structures, photoabsorption takes place in InGaAs QDs (due

  1. Composition and Interface Analysis of InGaN/GaN Multiquantum...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Composition and Interface Analysis of InGaNGaN Multiquantum-Wells on GaN Substrates Using Atom Probe Tomography. Composition and Interface Analysis of InGaNGaN Multiquantum-Wells...

  2. GaAs, AlGaAs and InGaP Tunnel Junctions for Multi-Junction Solar Cells Under Concentration: Resistance Study

    SciTech Connect (OSTI)

    Wheeldon, Jeffrey F.; Valdivia, Christopher E.; Walker, Alex; Kolhatkar, Gitanja; Hall, Trevor J.; Hinzer, Karin [Centre for Research in Photonics, University of Ottawa, Ottawa, ON (Canada); Masson, Denis; Riel, Bruno; Fafard, Simon [Cyrium Technologies Inc., Ottawa, ON (Canada); Jaouad, Abdelatif; Turala, Artur; Ares, Richard; Aimez, Vincent [Centre de Recherche en Nanofabrication et en Nanocaracterisation CRN2, Universite de Sherbrooke, Sherbrooke, QC (Canada)

    2010-10-14T23:59:59.000Z

    The following four TJ designs, AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs are studied to determine minimum doping concentration to achieve a resistance of <10{sup -4} {omega}{center_dot}cm{sup 2} and a peak tunneling current suitable for MJ solar cells up to 1500-suns concentration (operating current of 21 A/cm{sup 2}). Experimentally calibrated numerical models are used to determine how the resistance changes as a function of doping concentration. The AlGaAs/GaAs TJ design is determined to require the least doping concentration to achieve the specified resistance and peak tunneling current, followed by the GaAs/GaAs, and AlGaAs/AlGaAs TJ designs. The AlGaAs/InGaP TJ design can only achieve resistances >5x10{sup -4} {omega}cm{sup 2}.

  3. PRESSURE DEPENDENCE OF OPTICAL TRANSITIONS IN InGaN/GaN MULTIPLE QUANTUM WELLS

    E-Print Network [OSTI]

    McCluskey, Matthew

    -µm thick GaN layer deposited on a sapphire substrate, and it is capped by a 0.2-µm GaN:Mg pPRESSURE DEPENDENCE OF OPTICAL TRANSITIONS IN InGaN/GaN MULTIPLE QUANTUM WELLS W. Shan,* J.W. Ager pressure on optical transitions in InGaN/GaN multiple quantum wells (MQWs) has been studied

  4. Free carrier accumulation at cubic AlGaN/GaN heterojunctions Q. Y. Wei,1

    E-Print Network [OSTI]

    As, Donat Josef

    ) substrate,7 with GaN and AlGaN layer thickness of 600 nm and 30 nm, respectively. The layer thicknessFree carrier accumulation at cubic AlGaN/GaN heterojunctions Q. Y. Wei,1 T. Li,1 J. Y. Huang,1 F. A (Received 24 February 2012; accepted 19 March 2012; published online 3 April 2012) Cubic Al0.3Ga0.7N/GaN

  5. InGaP/GaAs/InGaP double-heterojunction bipolar transistors grown by solid-source molecular-beam epitaxy with a valved phosphorus cracker

    E-Print Network [OSTI]

    Woodall, Jerry M.

    InGaP/GaAs/InGaP double-heterojunction bipolar transistors grown by solid-source molecular; accepted 17 November 1995 The growth and device characterization of an InGaP/GaAs double-quality phosphorus-containing compounds.1­4 The growth of high-performance InGaP/ GaAs and InGaAs/InP single

  6. LA-12968-MS The Unsaturated Hydraulic

    E-Print Network [OSTI]

    LA-12968-MS The Unsaturated Hydraulic Characteristics of the BandelierTuff LosN A T I O N A L L A B technical correctness. #12;The Unsaturated Hydraulic Characteristics of the Bandelier Tuff David B. Rogers........................................................................................................4 Hydraulic Data Presentation

  7. InGaP/InGaAsN/GaAs NpN double-heterojunction bipolar transistor

    SciTech Connect (OSTI)

    Chang, P. C. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Baca, A. G. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Li, N. Y. [Emcore Photovoltaics, Emcore Corporation, Albuquerque, New Mexico 87123 (United States)] [Emcore Photovoltaics, Emcore Corporation, Albuquerque, New Mexico 87123 (United States); Xie, X. M. [Emcore Photovoltaics, Emcore Corporation, Albuquerque, New Mexico 87123 (United States)] [Emcore Photovoltaics, Emcore Corporation, Albuquerque, New Mexico 87123 (United States); Hou, H. Q. [Emcore Photovoltaics, Emcore Corporation, Albuquerque, New Mexico 87123 (United States)] [Emcore Photovoltaics, Emcore Corporation, Albuquerque, New Mexico 87123 (United States); Armour, E. [Emcore Corporation, Somerset, New Jersey 08873 (United States)] [Emcore Corporation, Somerset, New Jersey 08873 (United States)

    2000-04-17T23:59:59.000Z

    We have demonstrated a functional NpN double-heterojunction bipolar transistor (DHBT) using InGaAsN for the base layer. The InGaP/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs DHBT has a low V{sub ON} of 0.81 V, which is 0.13 V lower than in a InGaP/GaAs heterojunction bipolar transistor (HBT). The lower turn-on voltage is attributed to the smaller band gap (1.20 eV) of metalorganic chemical vapor deposition-grown In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} base layer. GaAs is used for the collector; thus the breakdown voltage (BV{sub CEO}) is 10 V, consistent with the BV{sub CEO} of InGaP/GaAs HBTs of comparable collector thickness and doping level. To alleviate the current blocking phenomenon caused by the larger conduction band discontinuity between InGaAsN and GaAs, a graded InGaAs layer with {delta} doping is inserted at the base-collector junction. The improved device has a peak current gain of seven with ideal current-voltage characteristics. (c) 2000 American Institute of Physics.

  8. InGaP/InGaAsN/GaAs NpN double heterojunction bipolar transistor

    SciTech Connect (OSTI)

    Chang, P.C.; Baca, A.G.; Li, N.Y.; Xie, X.M.; Sharps, P.R.; Hou, H.Q.

    2000-01-10T23:59:59.000Z

    The authors have demonstrated a functional NpN double heterojunction bipolar transistor (DHBT) using InGaAsN for base layer. The InGaP/In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01}/GaAs DHBT has a low V{sub ON} of 0.81 V, which is 0.13 V lower than in a InGaP/GaAs HBT. The lower V{sub ON} is attributed to the smaller bandgap (E{sub g}=1.20eV) of MOCVD grown In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} base layer. GaAs is used for the collector; thus the BV{sub CEO} is 10 V, consistent with the BV{sub CEO} of InGaP/GaAs Hbts of comparable collector thickness and doping level. To alleviate the current blocking phenomenon caused by the larger {triangle}E{sub C} between InGaAsN and GaAs, a graded InGaAs layer with {delta}-doping is inserted at the base-collector junction. The improved device has a peak current gain of 7 with ideal IV characteristics.

  9. Intrafacet migration effects in InGaN/GaN structures grown on triangular GaN ridges studied by submicron beam x-ray diffraction

    E-Print Network [OSTI]

    Sirenko, Andrei

    Intrafacet migration effects in InGaN/GaN structures grown on triangular GaN ridges studied for x-ray diffraction and reciprocal space mapping of InGaN/GaN multiple-quantum-well MQW structures grown on the sidewalls of 10- m-wide triangular GaN ridges with 1-1.1 facets. Samples were produced

  10. GaN0.011P0.989–GaP Double-Heterostructure Red Light-Emitting Diodes Directly Grown on GaP Substrates

    E-Print Network [OSTI]

    Tu, Charles W

    2000-01-01T23:59:59.000Z

    and C. W. Tu, GaN diodes on GaP substrates, 2000. [7] J. W.on a GaN directly grown on a GaP substrate was successfullyDH) directly a GaN grown on a (100) GaP substrate. Fig. 1(a)

  11. AlGaAs/InGaAsN/GaAs PnP double heterojunction bipolar transistor

    SciTech Connect (OSTI)

    Chang, P.C.; Baca, A.G.; Li, N.Y.; Sharps, P.R.; Hou, H.Q.; Laroche, J.R.; Ren, F.

    2000-01-11T23:59:59.000Z

    The authors have demonstrated a functional MOCVD-grown AlGaAs/InGaAsN/GaAsPnP DHBT that is lattice matched to GaAs and has a peak current gain ({beta}) of 25. Because of the smaller bandgap (E{sub g}=1.20eV)of In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} used for the base layer, this device has a low V{sub ON} of 0.79 V, 0.25 V lower than in a comparable Pnp AlGaAs/GaAs HBT. The BV{sub CEO} is 12 V, consistent with its GaAs collector thickness and doping level.

  12. Asymmetric interfacial abruptness in N-polar and Ga-polar GaN/AlN/GaN heterostructures

    SciTech Connect (OSTI)

    Mazumder, B.; Hurni, C. A.; Zhang, J. Y.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Wong, M. H.; Mishra, U. K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2012-08-27T23:59:59.000Z

    In this letter, we report on the interfacial abruptness of GaN/AlN/GaN heterostructures with pulsed laser atom probe tomography (APT). The samples were grown by plasma-assisted molecular beam epitaxy (MBE) under both metal-rich and N-rich conditions on both Ga-polar (0001) GaN templates and N-polar (0001) GaN substrates. An NH{sub 3} assisted MBE technique was involved to grow similar Ga-polar and N-polar structures on GaN:Fe substrates and GaN/Al{sub 2}O{sub 3} templates, respectively, for a comparison study. We find in all cases the interface with net positive polarization charge was chemically abrupt, whereas the interface with net negative polarization charge was diffuse. We discuss the implications on device design and performance. These data validate the efficiency of APT in studying interfaces for better performance in devices.

  13. Superior radiation-resistant properties of InGaP/GaAs tandem solar cells

    SciTech Connect (OSTI)

    Yamaguchi, M.; Okuda, T.; Taylor, S.J.; Takamoto, T. [Toyota Technological Institute 2-12-1 Hisakata, Tempaku, Nagoya 468 (Japan)] [Toyota Technological Institute 2-12-1 Hisakata, Tempaku, Nagoya 468 (Japan); Ikeda, E.; Kurita, H. [Central Resource Laboratory, Japan Energy Company, Niizo-Minami, Toda, Saitama 335 (Japan)] [Central Resource Laboratory, Japan Energy Company, Niizo-Minami, Toda, Saitama 335 (Japan)

    1997-03-01T23:59:59.000Z

    The observation of minority-carrier injection-enhanced annealing of radiation damage to InGa{sub 0.5}P{sub 0.5}/GaAs tandem solar cells is reported. Radiation resistance of InGaP/GaAs tandem solar cells as is similar with GaAs-on-Ge cells have been confirmed with 1 MeV electron irradiations. Moreover, minority-carrier injection under light illumination and forward bias conditions is shown to enhance defect annealing in InGaP and to result in the recovery of InGaP/GaAs tandem solar cell properties. These results suggest that the InGaP/GaAs(/Ge) multijunction solar cells and InGaP-based devices have great potential for space applications. {copyright} {ital 1997 American Institute of Physics.}

  14. MS 211 -CALCULO NUMERICO -1o http://www.ime.unicamp.br/ ms211/

    E-Print Network [OSTI]

    Sussner, Peter

    MS 211 - C´ALCULO NUM´ERICO - 1o SEM/2010 http://www.ime.unicamp.br/ ms211/ Turma Per Ruggiero e V´era Lucia da Rocha Lopes, C´alculo Num´erico - Aspectos Te´oricos e Computacionais, Pearson´etodos Num´ericos para as Engenharias e Ci^encias Aplicadas, Edi- tora da Unicamp, Campinas, segunda edi

  15. Beta decay of Ga-62

    E-Print Network [OSTI]

    Hyman, BC; Iacob, VE; Azhari, A.; Gagliardi, Carl A.; Hardy, John C.; Mayes, VE; Neilson, RG; Sanchez-Vega, M.; Tang, X.; Trache, L.; Tribble, Robert E.

    2003-01-01T23:59:59.000Z

    from the ex- perimental ft value for a 01?01 b decay between analog states with the relation @3# 0556-2813/2003/68~1!/015501~6!/$20.00 68 015501- of 62Ga . Hardy, V. E. Mayes, R. G. Neilson, M. Sanchez-Vega, and R. E. Tribble y, College Station...

  16. GaN nanowires show more 3D piezoelectricity than bulk GaN

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Logo GaN nanowires show more 3D piezoelectricity than bulk GaN admin / January 11, 2012 individual gallium nitride (GaN) nanowires showing strong piezoelectric effect in 3D. This is in spite of the fact that each nanowire only measures 100nm in diameter. While GaN is ubiquitous in optoelectronic

  17. Self-aligned AlGaN/GaN transistors for sub-mm wave applications

    E-Print Network [OSTI]

    Saadat, Omair I

    2010-01-01T23:59:59.000Z

    This thesis describes work done towards realizing self-aligned AlGaN/GaN high electron mobility transistors (HEMTs). Self-aligned transistors are important for improving the frequency of AlGaN/GaN HEMTs by reducing source ...

  18. Invited Paper GaN HEMT reliability

    E-Print Network [OSTI]

    del Alamo, Jesús A.

    Invited Paper GaN HEMT reliability J.A. del Alamo *, J. Joh Microsystems Technology Laboratories mechanism recently identified in GaN high-electron mobility transistors subject to electrical stress. Under high voltage, it has been found that electrically active defects are generated in the AlGaN barrier

  19. New GaInP/GaAs/GaInAs, Triple-Bandgap, Tandem Solar Cell for High-Efficiency Terrestrial Concentrator Systems

    SciTech Connect (OSTI)

    Kurtz, S.; Wanlass, M.; Kramer, C.; Young, M.; Geisz, J.; Ward, S.; Duda, A.; Moriarty, T.; Carapella, J.; Ahrenkiel, P.; Emery. K.; Jones, K.; Romero, M.; Kibbler, A.; Olson, J.; Friedman, D.; McMahon, W.; Ptak, A.

    2005-11-01T23:59:59.000Z

    GaInP/GaAs/GaInAs three-junction cells are grown in an inverted configuration on GaAs, allowing high quality growth of the lattice matched GaInP and GaAs layers before a grade is used for the 1-eV GaInAs layer. Using this approach an efficiency of 37.9% was demonstrated.

  20. Simultaneous MS-IR Studies of Surface Formate Reactivity Under...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    MS-IR Studies of Surface Formate Reactivity Under Methanol Synthesis Conditions on CuSiO2. Simultaneous MS-IR Studies of Surface Formate Reactivity Under Methanol Synthesis...

  1. Ms. Judy Clayton, Chair Paducah Citizens Advisory Board EHI Consultant...

    Office of Environmental Management (EM)

    0 Ms. Judy Clayton, Chair Paducah Citizens Advisory Board EHI Consultants, Inc. 1 1 1 Memorial Drive Paducah, Kentucky 4200 1 Dear Ms. Clayton: Thank you for your recent letter...

  2. MS.BIOLOGY.NON-THESIS ACADEMIC LEARNING PLAN

    E-Print Network [OSTI]

    O'Laughlin, Jay

    to constructive feedback Job Prospects for Biology Graduates MS/non-thesis in Biology Bioremediation Biotechnology Medical Research Industry Government Education Microbiology Health Professions Research Laboratories Find Food Production Pollution Control Environmental Diagnostics Forestry Agriculture #12;MS

  3. DEBRA ANNE ROACH, M.S. Assistant Dean

    E-Print Network [OSTI]

    Navara, Kristen

    #12;DEBRA ANNE ROACH, M.S. Assistant Dean Director Graduate Enrollment SEAN-MICHAEL GREEN, J.D., LL & Adult Enrollment 845-575-3512 sean-michael.green@marist.edu DEBRA ANNE ROACH, M.S. Assistant Dean

  4. Designing a Digital Version of British Library, Harley MS 4431 

    E-Print Network [OSTI]

    Laidlaw, James; Mansfield, Charlie

    2005-05-12T23:59:59.000Z

    Discusses design for the electronic transcription of MS BL Harley 4431 aims first of all to create a diplomatic corpus made up of the thirty works which Christine de Pizan included in the Queen’s MS. The generally accepted ...

  5. InAs=InGaP=GaAs heterojunction power Schottky rectifiers

    E-Print Network [OSTI]

    Woodall, Jerry M.

    InAs=InGaP=GaAs heterojunction power Schottky rectifiers A. Chen, M. Young and J.M. Woodall A low-matched InGaP on GaAs, to make a high-temperature power rectifier. The LT molecular beam epitaxy technique enables the formation of an abrupt interface between InAs and InGaP. This heterojunction rectifier

  6. Monolithic Millimeter-wave Distributed Amplifiers using AlGaN/GaN HEMTs

    E-Print Network [OSTI]

    York, Robert A.

    Monolithic Millimeter-wave Distributed Amplifiers using AlGaN/GaN HEMTs Rajkumar Santhakumar, Yi have been designed and fabricated using AlGaN/GaN HEMTs. One of them uses a standard HEMT for the unit-gate distributed amplifier achieves a CW peak output power of 1W and a PAE of about 16% at 4GHz. Index Terms -- GaN

  7. Role of strain in polarization switching in semipolar InGaN/GaN quantum wells

    E-Print Network [OSTI]

    Role of strain in polarization switching in semipolar InGaN/GaN quantum wells Qimin Yan,1,a Patrick November 2010 The effect of strain on the valence-band structure of 112¯2 semipolar InGaN grown on GaN D6 is calculated for GaN and InN using density functional theory with the Heyd­Scuseria­ Ernzerhof

  8. GaN/AlGaN heterojunction infrared detector responding in 814 and 2070 m ranges

    E-Print Network [OSTI]

    Perera, A. G. Unil

    GaN/AlGaN heterojunction infrared detector responding in 8­14 and 20­70 m ranges G. Ariyawansa, M October 2006 A GaN/AlGaN heterojunction interfacial work function internal photoemission infrared detector, the work demonstrates 54 m 5.5 THz operation of the detector based on 1s­2p± transition of Si donors in GaN

  9. Genizah MS T-S AS 154.342

    E-Print Network [OSTI]

    Unknown

    2011-02-24T23:59:59.000Z

    Possibly payment order or accounting, mentioning M?s? (?), Egypt and 'only three', with Persian-Arabic numerals....

  10. Effect of buffer structures on AlGaN/GaN high electron mobility transistor reliability

    SciTech Connect (OSTI)

    Liu, L. [University of Florida, Gainesville; Xi, Y. Y. [University of Florida, Gainesville; Ren, F. [University of Florida; Pearton, S. J. [University of Florida; Laboutin, O. [Kopin Corporation, Taunton, MA; Cao, Yu [Kopin Corporation, Taunton, MA; Johnson, Wayne J. [Kopin Corporation, Taunton, MA; Kravchenko, Ivan I [ORNL

    2012-01-01T23:59:59.000Z

    AlGaN/GaN high electron mobility transistors (HEMTs) with three different types of buffer layers, including a GaN/AlGaN composite layer, or 1 or 2 lm GaN thick layers, were fabricated and their reliability compared. The HEMTs with the thick GaN buffer layer showed the lowest critical voltage (Vcri) during off-state drain step-stress, but this was increased by around 50% and 100% for devices with the composite AlGaN/GaN buffer layers or thinner GaN buffers, respectively. The Voff - state for HEMTs with thin GaN and composite buffers were 100 V, however, this degraded to 50 60V for devices with thick GaN buffers due to the difference in peak electric field near the gate edge. A similar trend was observed in the isolation breakdown voltage measurements, with the highest Viso achieved based on thin GaN or composite buffer designs (600 700 V), while a much smaller Viso of 200V was measured on HEMTs with the thick GaN buffer layers. These results demonstrate the strong influence of buffer structure and defect density on AlGaN/GaN HEMT performance and reliability.

  11. 607 MS Major Code Major College Bachelor's Master's Doctor's

    E-Print Network [OSTI]

    Bolding, M. Chad

    Engineering CAFLS BS MS PhD 824 Biotechnology CAFLS MS 500 Business & Behavioral Science Entomology CAFLS MS PhD #12;402 General CES non 129 Environmental and Natural Res (Natural Resources CAFLS BS 126 Environmental and Natural Resources CAFLS nondegree 127 Environmental

  12. Master of Science (MS), Major: Chemical Engineering Apply Now

    E-Print Network [OSTI]

    Shihadeh, Alan

    Master of Science (MS), Major: Chemical Engineering Apply Now The Chemical Engineering Program to the following degrees: Master of Science, major Chemical Engineering The MS program will be open to students with a Bachelor of Science (BS) in Chemical Engineering, or other related disciplines. The MS program will also

  13. Growth of AlGaN/GaN heterojunction field effect transistors on semi-insulating GaN using an AlGaN interlayer

    SciTech Connect (OSTI)

    Chen, Z.; Denbaars, S. P. [Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Department, University of California, Santa Barbara, California 93106 (United States); Pei, Y.; Newman, S.; Chu, R.; Brown, D.; Keller, S.; Mishra, U. K. [Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Chung, R.; Nakamura, S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)

    2009-03-16T23:59:59.000Z

    Semi-insulating (SI) GaN layers were grown on 4H-SiC substrates by inserting an AlGaN layer between the AlN buffer and the GaN layer. Secondary ion mass spectroscopy measurements showed that the AlGaN layer prevented Si from diffusing from the substrate into the GaN layer. X-ray diffraction and atomic force microscopy analyses showed that an optimized AlGaN interlayer does not degrade the crystal quality or surface morphology of the SI GaN. The room temperature mobility of an AlGaN/GaN heterostructure using this SI GaN was 2200 cm{sup 2}/V s. High electron mobility transistors (HEMTs) with 0.65 {mu}m long gates were also fabricated on these SI GaN buffers. A power density of 19.0 W/mm with a power added efficiency of 48% was demonstrated at 10 GHz at a drain bias of 78 V. These HEMTs also exhibited sharp pinch off, low leakage, and negligible dispersion.

  14. Strain variations in InGaAsP/InGaP superlattices studied by scanning probe microscopy

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Strain variations in InGaAsP/InGaP superlattices studied by scanning probe microscopy Huajie Chen, Kista, Sweden Abstract Strain-compensated InGaAsP/InGaP superlattices are studied in cross- section. The strain compensated InGaAsP/InGaP/InP superlattices studied here have application for light sources

  15. AlGaN/GaN Metal Oxide Semiconductor Field Effect Transistors using Titanium Dioxide P. J. HANSEN

    E-Print Network [OSTI]

    York, Robert A.

    AlGaN/GaN Metal Oxide Semiconductor Field Effect Transistors using Titanium Dioxide P. J. HANSEN 1 epitaxially on AlGaN/GaN HFET structures by molecular beam epitaxy (MBE). Growth was first performed on GaN templates to establish epitaxial growth conditions. X-ray diffraction showed [001] TiO2 || [1010]GaN

  16. AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium titanate

    E-Print Network [OSTI]

    York, Robert A.

    AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium; published 13 October 2004) Use of high-k gate dielectrics in AlGaN/GaN heterostructure field transconductance and pinchoff voltage. To achieve this, AlGaN/GaN metal-oxide-semiconductor heterostructure field

  17. In this paper, an AlGaN/GaN high electron mobility transistor (HEMT) device based on a

    E-Print Network [OSTI]

    Yang, Kyounghoon

    205 Abstract In this paper, an AlGaN/GaN high electron mobility transistor (HEMT) device basedBm at 2 GHz have been demonstrated from the fabricated device. 1. Introduction In recent years, AlGaN/GaN noise amplifier and switch. Superior results have been reported in microwave power performance of AlGaN/GaN

  18. A New Architecture for AlGaN/GaN HEMT Frequency Doubler Using Active Integrated Antenna Design Approach

    E-Print Network [OSTI]

    Itoh, Tatsuo

    A New Architecture for AlGaN/GaN HEMT Frequency Doubler Using Active Integrated Antenna Design presents a new architecture for an AlGaN/GaN HEMT frequency doubler using the active integrated antenna. The antenna operates as a fundamental frequency reflector in this circuit. Using AlGaN/GaN with 1mm gate

  19. Generation-Recombination Defects In AlGaN/GaN HEMT On SiC Substrate,

    E-Print Network [OSTI]

    Boyer, Edmond

    Generation-Recombination Defects In AlGaN/GaN HEMT On SiC Substrate, Evidenced By Low Frequency Aristide Briand, 92.195 Meudon, France Abstract. Wide bandgap devices such as AlGaN/GaN High Electron of GR- bulges related respectively to AlGaN/GaN interface and quantum well are identified. Each GR

  20. Effect of dislocations on electron mobility in AlGaN/GaN and AlGaN/AlN/GaN heterostructures

    SciTech Connect (OSTI)

    Kaun, Stephen W.; Burke, Peter G.; Kyle, Erin C. H.; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Wong, Man Hoi; Mishra, Umesh K. [Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

    2012-12-24T23:59:59.000Z

    Al{sub x}Ga{sub 1-x}N/GaN (x = 0.06, 0.12, 0.24) and AlGaN/AlN/GaN heterostructures were grown on 6 H-SiC, GaN-on-sapphire, and free-standing GaN, resulting in heterostructures with threading dislocation densities of {approx}2 Multiplication-Sign 10{sup 10}, {approx}5 Multiplication-Sign 10{sup 8}, and {approx}5 Multiplication-Sign 10{sup 7} cm{sup -2}, respectively. All growths were performed under Ga-rich conditions by plasma-assisted molecular beam epitaxy. Dominant scattering mechanisms with variations in threading dislocation density and sheet concentration were indicated through temperature-dependent Hall measurements. The inclusion of an AlN interlayer was also considered. Dislocation scattering contributed to reduced mobility in these heterostructures, especially when sheet concentration was low or when an AlN interlayer was present.

  1. High efficiency InGaP solar cells for InGaP/GaAs tandem cell application

    SciTech Connect (OSTI)

    Takamoto, T.; Ikeda, E.; Kurita, H.; Ohmori, M. [Japan Energy Corp., Toda, Saitama (Japan). Central Research Lab.

    1994-12-31T23:59:59.000Z

    In this paper, high conversion efficiency single junction InGaP solar cells with n-p-p{sup +} structure are presented and their application to InGaP/GaAs monolithic tandem cells is discussed. In the InGaP cells, a best conversion efficiency of 18.48% was achieved by introducing the p{sup +} peak back surface field (BSF) layer with a high carrier concentration of 2 {times} 10{sup 18} cm{sup {minus}3}, which improved both short circuit current (Isc) and open circuit voltage (Voc). However, in the case of InGaP/GaAs tandem cells, a decrease in carrier concentration of the InGaP BSF layer, which was caused by the diffusion of Zn, was found to reduce the Isc and Voc of the tandem cell. The reduction in the carrier concentration was suppressed by using a thicker BSF layer of 0.5 {micro}m, which reduced the current density in the GaAs bottom cell. An InGaP/GaAs tandem cell with 27.3% efficiency and a high Voc of 2.418 V was obtained.

  2. Relaxed, high-quality InP on GaAs by using InGaAs and InGaP graded buffers to avoid phase separation

    E-Print Network [OSTI]

    Relaxed, high-quality InP on GaAs by using InGaAs and InGaP graded buffers to avoid phaseAs was 70% of that on bulk InP at both temperatures. To achieve this, graded buffers in the InGaAs, InGaP

  3. AlGaN/GaN HEMTs grown by Molecular Beam Epitaxy on sapphire, Sic, and HVPE GaN templates

    E-Print Network [OSTI]

    Manfra, Michael J.

    PS-4 AlGaN/GaN HEMTs grown by Molecular Beam Epitaxy on sapphire, Sic, and HVPE GaN templates Nils ABSTRACT Molecular Beam Epitaxy of GaN and related alloys is becoming a rival to the more established, and HVPE SI-GaN templates on sapphire. While sapphire and SI-Sic are established substrates for the growth

  4. ZrO2 gate dielectrics produced by ultraviolet ozone oxidation for GaN and AlGaN/GaN transistors

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    MOSCAP process ?ow: n-GaN substrate; Ohmic metallization andtion for a AlGaN/ GaN HEMT on a substrate which has a poorsapphire substrate, a well-passivated AlGaN/ GaN HEMT grown

  5. ARM - Campaign Instrument - ptr-ms

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492air Comments? We would love to hear from you!jpl Comments?govInstrumentsprecipisogovInstrumentsptr-ms

  6. To: Ms. Dorothy Riehle, FOIA Officer,

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level:Energy: Grid Integration Redefining What'sis Taking Over OurThe Iron Spin Transition in2, 2003 (NextTime-ResolvedTo: Ms. Dorothy Riehle, FOIA

  7. LA-8318-MS Informal Report I

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492 742EnergyOnItem Not Found Item Not Found TheHot electron dynamics in grapheneInverter8318-MS

  8. Green light emission by InGaN/GaN multiple-quantum-well microdisks

    SciTech Connect (OSTI)

    Hsu, Yu-Chi; Lo, Ikai, E-mail: ikailo@mail.phys.nsysu.edu.tw; Shih, Cheng-Hung; Pang, Wen-Yuan; Hu, Chia-Hsuan; Wang, Ying-Chieh; Tsai, Cheng-Da; Chou, Mitch M. C. [Department of Physics, Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)] [Department of Physics, Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Hsu, Gary Z. L. [United Crystal Corporation, No. 243-3, Wenshan 36061, Miaoli, Taiwan (China)] [United Crystal Corporation, No. 243-3, Wenshan 36061, Miaoli, Taiwan (China)

    2014-03-10T23:59:59.000Z

    The high-quality In{sub x}Ga{sub 1?x}N/GaN multiple quantum wells were grown on GaN microdisks with ?-LiAlO{sub 2} substrate by using low-temperature two-step technique of plasma-assisted molecular beam epitaxy. We demonstrated that the hexagonal GaN microdisk can be used as a strain-free substrate to grow the advanced In{sub x}Ga{sub 1?x}N/GaN quantum wells for the optoelectronic applications. We showed that the green light of 566-nm wavelength (2.192?eV) emitted from the In{sub x}Ga{sub 1?x}N/GaN quantum wells was tremendously enhanced in an order of amplitude higher than the UV light of 367-nm wavelength (3.383?eV) from GaN.

  9. InGaAsN/GaAs heterojunction for multi-junction solar cells

    DOE Patents [OSTI]

    Kurtz, Steven R. (Albuquerque, NM); Allerman, Andrew A. (Albuquerque, NM); Klem, John F. (Albuquerque, NM); Jones, Eric D. (Edgewood, NM)

    2001-01-01T23:59:59.000Z

    An InGaAsN/GaAs semiconductor p-n heterojunction is disclosed for use in forming a 0.95-1.2 eV bandgap photodetector with application for use in high-efficiency multi-junction solar cells. The InGaAsN/GaAs p-n heterojunction is formed by epitaxially growing on a gallium arsenide (GaAs) or germanium (Ge) substrate an n-type indium gallium arsenide nitride (InGaAsN) layer having a semiconductor alloy composition In.sub.x Ga.sub.1-x As.sub.1-y N.sub.y with 0GaAs layer, with the InGaAsN and GaAs layers being lattice-matched to the substrate. The InGaAsN/GaAs p-n heterojunction can be epitaxially grown by either molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD). The InGaAsN/GaAs p-n heterojunction provides a high open-circuit voltage of up to 0.62 volts and an internal quantum efficiency of >70%.

  10. InGaP/GaAs and InGaAs mechanically-stacked triple-junction solar cells

    SciTech Connect (OSTI)

    Takamoto, T.; Ikeda, E.; Agui, T. [Japan Energy Corp., Toda, Saitama (Japan)] [and others

    1997-12-31T23:59:59.000Z

    Triple-junction cells with AM1.5 efficiencies of over 33% have been demonstrated. A planar type InGaP/GaAs monolithic dual-junction cell was fabricated on a semi-insulating FaAs substrate, which has high infra-red transparency. Then a dual-junction cell, with efficiency of 27--28%, was mechanically stacked on an InGaAs cell fabricated on an InP substrate. The bottom InGaAs cell showed an efficiency of 6.2% under the InGaP/GaAs cell, and a total efficiency of 33--34% was achieved for the four-terminal triple-junction cell.

  11. Graphene induced remote surface scattering in graphene/AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Liu, Xiwen; Li, Dan; Wang, Bobo; Liu, Bin; Chen, Famin; Jin, Guangri; Lu, Yanwu, E-mail: ywlu@bjtu.edu.cn [Department of Physics, Beijing Jiaotong University, Beijing 100044 (China)

    2014-10-20T23:59:59.000Z

    The mobilities of single-layer graphene combined with AlGaN/GaN heterostructures on two-dimensional electron gases in graphene/AlGaN/GaN double heterojunction are calculated. The impact of electron density in single-layer graphene is also studied. Remote surface roughness (RSR) and remote interfacial charge (RIC) scatterings are introduced into this heterostructure. The mobilities limited by RSR and RIC are an order of magnitude higher than that of interface roughness and misfit dislocation. This study contributes to designing structures for generation of higher electron mobility in graphene/AlGaN/GaN double heterojunction.

  12. Experimental evidence of Ga-vacancy induced room temperature ferromagnetic behavior in GaN films

    SciTech Connect (OSTI)

    Roul, Basanta; Kumar, Mahesh [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S. B. [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India); Kalghatgi, A. T. [Central Research Laboratory, Bharat Electronics, Bangalore 560013 (India); Kumar, Nitesh; Sundaresan, A. [Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560064 (India)

    2011-10-17T23:59:59.000Z

    We have grown Ga deficient GaN epitaxial films on (0001) sapphire substrate by plasma-assisted molecular beam epitaxy and report the experimental evidence of room temperature ferromagnetic behavior. The observed yellow emission peak in room temperature photoluminescence spectra and the peak positioning at 300 cm{sup -1} in Raman spectra confirms the existence of Ga vacancies. The x-ray photoelectron spectroscopic measurements further confirmed the formation of Ga vacancies; since the N/Ga is found to be >1. The ferromagnetism is believed to originate from the polarization of the unpaired 2p electrons of N surrounding the Ga vacancy.

  13. Ultra-Thin, Triple-Bandgap GaInP/GaAs/GaInAs Monolithic Tandem Solar Cells

    SciTech Connect (OSTI)

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

    2007-02-01T23:59:59.000Z

    The performance of state-of-the-art, series-connected, lattice-matched (LM), triple-junction (TJ), III-V tandem solar cells could be improved substantially (10-12%) by replacing the Ge bottom subcell with a subcell having a bandgap of {approx}1 eV. For the last several years, research has been conducted by a number of organizations to develop {approx}1-eV, LM GaInAsN to provide such a subcell, but, so far, the approach has proven unsuccessful. Thus, the need for a high-performance, monolithically integrable, 1-eV subcell for TJ tandems has remained. In this paper, we present a new TJ tandem cell design that addresses the above-mentioned problem. Our approach involves inverted epitaxial growth to allow the monolithic integration of a lattice-mismatched (LMM) {approx}1-eV GaInAs/GaInP double-heterostructure (DH) bottom subcell with LM GaAs (middle) and GaInP (top) upper subcells. A transparent GaInP compositionally graded layer facilitates the integration of the LM and LMM components. Handle-mounted, ultra-thin device fabrication is a natural consequence of the inverted-structure approach, which results in a number of advantages, including robustness, potential low cost, improved thermal management, incorporation of back-surface reflectors, and possible reclamation/reuse of the parent crystalline substrate for further cost reduction. Our initial work has concerned GaInP/GaAs/GaInAs tandem cells grown on GaAs substrates. In this case, the 1-eV GaInAs experiences 2.2% compressive LMM with respect to the substrate. Specially designed GaInP graded layers are used to produce 1-eV subcells with performance parameters nearly equaling those of LM devices with the same bandgap (e.g., LM, 1-eV GaInAsP grown on InP). Previously, we reported preliminary ultra-thin tandem devices (0.237 cm{sup 2}) with NREL-confirmed efficiencies of 31.3% (global spectrum, one sun) (1), 29.7% (AM0 spectrum, one sun) (2), and 37.9% (low-AOD direct spectrum, 10.1 suns) (3), all at 25 C. Here, we include recent results of testing similar devices under the concentrated AMO spectrum, and also present the first demonstration of a high-efficiency, ultra-thin GaInP/GaAs/GaInAs tandem cell processed on a flexible kapton handle.

  14. September 16-21, 2007 Las Vegas, Nevada Gate recess technology on AlGaN/GaN HFET with InGaN as etch-stop layer

    E-Print Network [OSTI]

    Pala, Nezih

    0 2 V(V) C(pF) Before etching (material) After etching (device) G AlGaN substrate i-GaN DS AlN AlGaN substrate AlN i-GaN AlGaN S G DAlGaNAlGaN InGaNInGaN Standard gate recess InGaN stop layer gate recess InGaNICNS 7 September 16-21, 2007 ­ Las Vegas, Nevada Gate recess technology on AlGaN/GaN HFET with InGaN

  15. Rutile films grown by molecular beam epitaxy on GaN and AlGaN/GaN P. J. Hansen

    E-Print Network [OSTI]

    York, Robert A.

    Rutile films grown by molecular beam epitaxy on GaN and AlGaN/GaN P. J. Hansen Materials Department March 2005 Titanium dioxide TiO2, with the rutile structure was grown on 0001 oriented GaN and 0001 Al0.33Ga0.67N/GaN heterostructure field effect transistor HFET structures by molecular beam epitaxy. X

  16. Single-Wire Light-Emitting Diodes Based on GaN Wires Containing Both Polar and Nonpolar InGaN/GaN Quantum Wells

    E-Print Network [OSTI]

    Single-Wire Light-Emitting Diodes Based on GaN Wires Containing Both Polar and Nonpolar InGaN/GaN based on radial p­i­n multi quantum well (QW) junctions have been realized from GaN wires grown by catalyst- free metal organic vapor phase epitaxy. The Inx Ga1Àx N/GaN undoped QW system is coated over both

  17. High density plasma damage in InGaP/GaAs as AlGaAs/GaAs high electron mobility transistors

    SciTech Connect (OSTI)

    Lee, J.W.; Pearton, S.J. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering; Ren, F.; Kopf, R.F.; Kuo, J.M. [Bell Labs., Murray Hill, NJ (United States). Lucent Technologies; Shul, R.J. [Sandia National Labs., Albuquerque, NM (United States); Constantine, C.; Johnson, D. [Plasma-Therm Inc., St. Petersburg, FL (United States)

    1998-11-01T23:59:59.000Z

    The introduction of plasma damage in InGaP/GaAs and AlGaAs/GaAs high electron mobility transistors (HEMTs) has been investigated using both inductively coupled plasma and electron cyclotron resonance Ar discharges. The saturated drain-source current is found to be decreased through introduction of compensating deep levels into the InGaP or AlGaAs donor layer. The degradation of device performance is a strong function of ion energy and ion flux, and an advantage of both high density plasma tools is that ion energy can be reduced by increasing the plasma density. Increasing process pressure and source power, and decreasing radio-frequency chuck power produce the lowest amounts of plasma damage in HEMTs.

  18. Comparison of compressive and tensile relaxed composition-graded GaAsP and ,,Al...InGaP substrates

    E-Print Network [OSTI]

    Comparison of compressive and tensile relaxed composition-graded GaAsP and ,,Al...InGaP substrates, around 104 cm-2 . The structures, grown on GaP or GaAs, consist of graded In-fraction InGaP and AlInGaP. High surface roughness and branch defects in Al InGaP lead to the lowest quality virtual substrates we

  19. Carrier Dynamics in InGaN/GaN SQW Structure Probed by the Transient Grating Method

    E-Print Network [OSTI]

    Okamoto, Koichi

    Carrier Dynamics in InGaN/GaN SQW Structure Probed by the Transient Grating Method; 78.55.Cr; 78.67.De; S7.14 Carrier dynamics in GaN and InGaN/GaN SQW structures were observed by using inhomogeneity of In composition. Recently, InGaN/GaN-based light emitting diodes (LEDs) have been commercialized

  20. N-Face GaN/AlGaN HEMTs Fabricated Through Layer Transfer Technology

    E-Print Network [OSTI]

    Chung, Jinwook

    We present a new method to fabricate N-face GaN/AlGaN high electron mobility transistors (HEMTs). These devices are extremely promising for ultrahigh frequency applications where low contact resistances and excellent carrier ...

  1. Development and Industrialization of InGaN/GaN LEDs on Patterned...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    of InGaNGaN LEDs on Patterned Sapphire Substrates for Low Cost Emitter Architecture Development and Industrialization of InGaNGaN LEDs on Patterned Sapphire...

  2. Breakdown mechanism in AlGaN/GaN HEMTs on Si substrate

    E-Print Network [OSTI]

    Lu, Bin

    AlGaN/GaN high electron mobility transistors (HEMTs) grown on Si substrates have attracted a great interest for power electronics applications. Despite the low cost of the Si substrate, the breakdown voltage (V[subscript ...

  3. Siemens Pittsburgh, PA Novelis Corporation Atlanta, GA

    E-Print Network [OSTI]

    McGaughey, Alan

    Industrial Design ­ Shanghai, China Eaton Corporation ­ Pittsburgh, PA CMU, CTTEC ­ PittsburghSiemens ­ Pittsburgh, PA Novelis Corporation ­ Atlanta, GA Expense

  4. Strain-balanced InGaN/GaN multiple quantum wells

    SciTech Connect (OSTI)

    Van Den Broeck, D. M.; Hosalli, A. M.; Bedair, S. M. [Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Bharrat, D.; El-Masry, N. A. [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-07-21T23:59:59.000Z

    InGaN/GaN multiple quantum well (MQW) structures suffer from a high amount of compressive strain in the InGaN wells and the accompanied piezoelectric field resulting in both a blue shift in emission and a reduction of emission intensity. We report the growth of In{sub x}Ga{sub 1?x}N/GaN “strain-balanced” multiple quantum wells (SBMQWs) grown on thick In{sub y}Ga{sub 1?y}N templates for x?>?y by metal organic chemical vapor deposition. SBMQWs consist of alternating layers of In{sub x}Ga{sub 1?x}N wells and GaN barriers under compressive and tensile stress, respectively, which have been lattice matched to a thick In{sub y}Ga{sub 1?y}N template. Growth of the In{sub y}Ga{sub 1?y}N template is also detailed in order to achieve thick, relaxed In{sub y}Ga{sub 1?y}N grown on GaN without the presence of V-grooves. When compared to conventional In{sub x}Ga{sub 1?x}N/GaN MQWs grown on GaN, the SBMQW structures exhibit longer wavelength emission and higher emission intensity for the same InN mole fraction due to a reduction in the well strain and piezoelectric field. By matching the average lattice constant of the MQW active region to the lattice constant of the In{sub y}Ga{sub 1?y}N template, essentially an infinite number of periods can be grown using the SBMQW growth method without relaxation-related effects. SBMQWs can be utilized to achieve longer wavelength emission in light emitting diodes without the use of excess indium and can be advantageous in addressing the “green gap.”.

  5. High current gain InGaN=GaN HBTs with C operating temperature

    E-Print Network [OSTI]

    Asbeck, Peter M.

    with an $20 nm low-temperature (Tg ¼ 550 C) GaN buffer layer on a (0001) sapphire substrate. The layer 1018 cmÀ3 Buffer GaN 2.5 mm ­ Substrate Sapphire ­ ­ HBT device processing began by depositing a 100 nmHigh current gain InGaN=GaN HBTs with 300 C operating temperature D.M. Keogh, P.M. Asbeck, T. Chung

  6. Switchable piezoelectric transduction in AlGaN/GaN MEMS resonators

    E-Print Network [OSTI]

    Weinstein, Dana

    This work presents a new switching mechanism in piezoelectric transduction of AlGaN/GaN bulk acoustic resonators. A piezoelectric transducer is formed in the AlGaN, between a top Schottky electrode and a 2D electron gas ...

  7. Spontaneous emission in GaN/InGaN photonic crystal nanopillars

    E-Print Network [OSTI]

    Boyer, Edmond

    . Sigalas, "InGaN/GaN quantum-well heterostructure light-emitting diodes employing photonic crystal, "III-nitride blue and ultraviolet photonic crystal light emitting diodes," Appl. Phys. Lett. 84, 466, and H. Benisty, "Photonic-crystal GaN light-emitting diodes with tailored guided modes distribution

  8. GaInP/GaAs/GaInAs Monolithic Tandem Cells for High-Performance Solar Concentrators

    SciTech Connect (OSTI)

    Wanlass, M. W.; Ahrenkiel, S. P.; Albin, D. S.; Carapella, J. J.; Duda, A.; Emery, K.; Geisz, J. F.; Jones, K.; Kurtz, S.; Moriarty, T.; Romero, M. J.

    2005-08-01T23:59:59.000Z

    We present a new approach for ultra-high-performance tandem solar cells that involves inverted epitaxial growth and ultra-thin device processing. The additional degree of freedom afforded by the inverted design allows the monolithic integration of high-, and medium-bandgap, lattice-matched (LM) subcell materials with lower-bandgap, lattice-mismatched (LMM) materials in a tandem structure through the use of transparent compositionally graded layers. The current work concerns an inverted, series-connected, triple-bandgap, GaInP (LM, 1.87 eV)/GaAs (LM, 1.42 eV)/GaInAs (LMM, {approx}1 eV) device structure grown on a GaAs substrate. Ultra-thin tandem devices are fabricated by mounting the epiwafers to pre-metallized Si wafer handles and selectively removing the parent GaAs substrate. The resulting handle-mounted, ultra-thin tandem cells have a number of important advantages, including improved performance and potential reclamation/reuse of the parent substrate for epitaxial growth. Additionally, realistic performance modeling calculations suggest that terrestrial concentrator efficiencies in the range of 40-45% are possible with this new tandem cell approach. A laboratory-scale (0.24 cm2), prototype GaInP/GaAs/GaInAs tandem cell with a terrestrial concentrator efficiency of 37.9% at a low concentration ratio (10.1 suns) is described, which surpasses the previous world efficiency record of 37.3%.

  9. Alignment of LC-MS Data Using Peptide Features

    E-Print Network [OSTI]

    Tang, Xincheng

    2012-02-14T23:59:59.000Z

    Spectrometry MALDI Matrix Assisted Laser Desorption Ionization MS Mass Spectrometry MS/MS Tandem Mass Spectrometry M/Z Mass-To-Charge Ratio PNNL Paci c Northwest National Laboratory RT Retention Time SELDI Surface Enhanced Laser Desorption Ionization... alignment. In this paper, two Shewanella datasets are obtained from Paci c Northwest Na- tional Laboratory (PNNL) and they were analyzed by SEQUEST on di erent days. SEQUEST correlates uninterpreted tandem mass spectra of peptides with amino acid...

  10. Fine structure of Fe-Co-Ga and Fe-Cr-Ga alloys with low Ga content

    SciTech Connect (OSTI)

    Kleinerman, Nadezhda M., E-mail: kleinerman@imp.uran.ru; Serikov, Vadim V., E-mail: kleinerman@imp.uran.ru; Vershinin, Aleksandr V., E-mail: kleinerman@imp.uran.ru; Mushnikov, Nikolai V., E-mail: kleinerman@imp.uran.ru; Stashkova, Liudmila A., E-mail: kleinerman@imp.uran.ru [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation)

    2014-10-27T23:59:59.000Z

    Investigation of Ga influence on the structure of Fe-Cr and Fe-Co alloys was performed with the use of {sup 57}Fe Mössbauer spectroscopy and X-ray diffraction methods. In the alloys of the Fe-Cr system, doping with Ga handicaps the decomposition of solid solutions, observed in the binary alloys, and increases its stability. In the alloys with Co, Ga also favors the uniformity of solid solutions. The analysis of Mössbauer experiments gives some grounds to conclude that if, owing to liquation, clusterization, or initial stages of phase separation, there exist regions enriched in iron, some amount of Ga atoms prefer to enter the nearest surroundings of iron atoms, thus forming binary Fe-Ga regions (or phases)

  11. TEM Characterization of InAs/GaAs Quantum Dots Capped by a GaSb/GaAs Layer

    SciTech Connect (OSTI)

    Beltran, AM [Universidad de Cadiz, Spain; Ben, Teresa [Universidad de Cadiz, Spain; Sanchez, AM [Universidad de Cadiz, Spain; Sales Lerida, David [ORNL; Chisholm, Matthew F [ORNL; Varela del Arco, Maria [ORNL; Pennycook, Stephen J [ORNL; Galindo, Pedro [Universidad de Cadiz, Spain; Ripalda, JM [Instituto de Microelectronica de Madrid (CNM, CSIC); Molina Rubio, Sergio I [ORNL

    2008-01-01T23:59:59.000Z

    It is well known that there is intense interest in expanding the usable wavelength for electronic devices. This is one of the reasons to study new self-assembled semiconductor nanostructures. Telecommunication applications use InGaAsP/InP emitting at 1.3 and 1.55 m. Research efforts are dedicated to develop GaAs technology in order to achieve emission at the same range as InP, so GaAs could be used for optical fibre communications. Ga(As)Sb on InAs/GaAs quantum dots (QDs) is a promising nanostructure to be used in telecommunications. The introduction of antimony during or after the QDs growth is an effective solution to obtain a red shift in the emission wavelength, even at room temperature.

  12. Excitonic properties of strained wurtzite and zinc-blende GaNAlxGa1xN quantum dots

    E-Print Network [OSTI]

    Fonoberov, Vladimir

    Excitonic properties of strained wurtzite and zinc-blende GaNÕAlxGa1ÀxN quantum dots Vladimir A 2003 We investigate exciton states theoretically in strained GaN/AlN quantum dots with wurtzite WZ of GaN QDs.1­8 Molecu- lar beam epitaxial growth in the Stranski­Krastanov mode of wurtzite WZ Ga

  13. Morphological and compositional variations in strain-compensated InGaAsP/InGaP superlattices

    E-Print Network [OSTI]

    Feenstra, Randall

    Morphological and compositional variations in strain- compensated InGaAsP/InGaP superlattices R of Technology, Kista, Sweden Abstract We have investigated the properties of strain-compensated InGaAsP/In- GaP superlattices, grown by metalorganic vapor phase epitaxy, with and without InP interlayers inserted in the InGaP

  14. Operating Characteristics of GaAs/InGaP Self Aligned Stripe Lasers Benjamin J. Stevens1

    E-Print Network [OSTI]

    Operating Characteristics of GaAs/InGaP Self Aligned Stripe Lasers Benjamin J. Stevens1 , Kristian of GaAs based self-aligned lasers based upon a single overgrowth. A lattice matched n-doped InGaP layer were exposed to oxygen. True buried heterostructures devices utilising InGaP clad- ding layers have

  15. Microstructure and luminescent properties of novel InGaP alloys on relaxed GaAsP substrates

    E-Print Network [OSTI]

    Microstructure and luminescent properties of novel InGaP alloys on relaxed GaAsP substrates M. J of unconventional alloys of InGaP with In fraction of 0.2­0.4 grown on fully relaxed GaAsP virtual substrates demonstrate growth of extremely high quality InGaP heterostructures which hold promise for fabrication

  16. Band Offsets of InGaP/GaAs Heterojunctions by Scanning Tunneling Spectroscopy Y. Dong and R. M. Feenstra

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Band Offsets of InGaP/GaAs Heterojunctions by Scanning Tunneling Spectroscopy Y. Dong and R. M Abstract Scanning tunneling microscopy and spectroscopy are used to study InGaP/GaAs heterojunctions computation of the tunnel current. Curve fitting of theory to experiment is performed. Using an InGaP band gap

  17. Negative capacitance in GaN/AlGaN heterojunction dual-band detectors L. E. Byrum,1

    E-Print Network [OSTI]

    Dietz, Nikolaus

    Negative capacitance in GaN/AlGaN heterojunction dual-band detectors L. E. Byrum,1 G. Ariyawansa,1 online 2 September 2009 A study of trap states in n+ -GaN/AlGaN heterostructures using electrical related absorption centers attributed to shallow Si-donor pinned to the AlGaN barrier , N-vacancy/ C

  18. High Power Wideband AlGaN/GaN HEMT Feedback Amplifier Module with Drain and Feedback Loop

    E-Print Network [OSTI]

    Itoh, Tatsuo

    High Power Wideband AlGaN/GaN HEMT Feedback Amplifier Module with Drain and Feedback Loop amplifier module using AlGaN/GaN high electron mobility transistor (HEMT) has been developed that covers radars and communications systems. GaN-based HEMT's for high power applications at microwave frequencies

  19. Impact ionization in N-polar AlGaN/GaN high electron mobility transistors

    SciTech Connect (OSTI)

    Killat, N., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk; Uren, M. J.; Kuball, M., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk [Center for Device Thermography and Reliability (CDTR), H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Keller, S.; Kolluri, S.; Mishra, U. K. [Department of Electrical and Computer Engineering, University of Santa Barbara California, Santa Barbara, California 93106 (United States)

    2014-08-11T23:59:59.000Z

    The existence of impact ionization as one of the open questions for GaN device reliability was studied in N-polar AlGaN/GaN high electron mobility transistors. Electroluminescence (EL) imaging and spectroscopy from underneath the device gate contact revealed the presence of hot electrons in excess of the GaN bandgap energy even at moderate on-state bias conditions, enabling impact ionization with hole currents up to several hundreds of pA/mm. The detection of high energy luminescence from hot electrons demonstrates that EL analysis is a highly sensitive tool to study degradation mechanisms in GaN devices.

  20. Michael J. Poston Atlanta, GA 30307

    E-Print Network [OSTI]

    Orlando, Thomas

    Page | 1 Michael J. Poston Atlanta, GA 30307 Michael.Poston@gatech.edu Cell: 770.561.4756 U.S. Citizen Education PhD Candidate in Chemistry Georgia Institute of Technology, Atlanta, GA August 2007 with Application to Lunar Observations," JGR ­ Planets, 118, 105, doi: 10.1002/jgre.20025. Poston, M. J

  1. Tunable two-dimensional plasmon resonances in an InGaAs/InP high electron mobility transistor

    E-Print Network [OSTI]

    Peale, Robert E.

    of materials systems such as GaAs/AlGaAs,3 InGaP/InGaAs/GaAs,4 GaN/AlGaN,2,5 and Si Ref. 1 have been explored

  2. FUPWG Meeting Agenda - Atlanta, GA | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Atlanta, GA FUPWG Meeting Agenda - Atlanta, GA Energy on My Mind FUPWG Atlanta, GA May 3-4, 2006 Hosted by: AGL Resources Logo May 3-4, 2006 Hosted by AGL Resources Atlanta,...

  3. AlGaN/GaN heterostructure prepared on a Si (110) substrate via pulsed sputtering

    SciTech Connect (OSTI)

    Watanabe, T.; Ohta, J.; Kondo, T.; Ohashi, M.; Ueno, K.; Kobayashi, A. [Institute of Industrial Science (IIS), The University of Tokyo, 4-6-1 Komaba, Tokyo 153-8505 (Japan); Fujioka, H., E-mail: hfujioka@iis.u-tokyo.ac.jp [Institute of Industrial Science (IIS), The University of Tokyo, 4-6-1 Komaba, Tokyo 153-8505 (Japan); CREST, Japan Science and Technology Corporation (JST), 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075 (Japan)

    2014-05-05T23:59:59.000Z

    GaN films were grown on Si (110) substrates using a low-temperature growth technique based on pulsed sputtering. Reduction of the growth temperature suppressed the strain in the GaN films, leading to an increase in the critical thickness for crack formation. In addition, an AlGaN/GaN heterostructure with a flat heterointerface was prepared using this technique. Furthermore, the existence of a two dimensional electron gas at the heterointerface with a mobility of 1360 cm{sup 2}/Vs and a sheet carrier density of 1.3?×?10{sup 13}?cm{sup ?2} was confirmed. Finally, the use of the AlGaN/GaN heterostructure in a high electron mobility transistor was demonstrated. These results indicate that low-temperature growth via pulsed sputtering is quite promising for the fabrication of GaN-based electronic devices.

  4. 56 IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 1, JANUARY 2012 Metamorphic GaAsP and InGaP Solar Cells on GaAs

    E-Print Network [OSTI]

    Haller, Gary L.

    56 IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 1, JANUARY 2012 Metamorphic GaAsP and InGaP Solar bandgap range. Index Terms--Epitaxy, GaAsP, InGaP, metamorphic. I. INTRODUCTION TODAY'S highest efficiency

  5. Defect structures in rapidly degraded InGaAsP/InGaP double-heterostructure lasers

    SciTech Connect (OSTI)

    Ueda, O.; Wakao, K.; Yamaguchi, A.; Isozumi, S.; Komiya, S.

    1985-03-01T23:59:59.000Z

    Rapidly degraded InGaAsP/InGaP double-heterostructure lasers grown on (001)-oriented GaAs substrates by liquid phase epitaxy have been investigated by photolumi

  6. Emission properties of heterostructures with a (GaAsSb-InGaAs)/GaAs bilayer quantum well

    SciTech Connect (OSTI)

    Zvonkov, B. N.; Nekorkin, S. M.; Vikhrova, O. V.; Dikareva, N. V., E-mail: dikareva@nifti.unn.ru [Nizhni Novgorod State University, Physical-Technical Research Institute (Russian Federation)

    2013-09-15T23:59:59.000Z

    The specific features of the emission characteristics of GaAs-based heterostructures with a GaAs{sub 1-x}Sb{sub x}-In{sub y}Ga{sub 1-y}As bilayer quantum well are studied. The heterostructures are grown by metal-organic chemical vapor deposition (MOCVD). With an analysis of previously reported data on the MOCVD growth process taken into account, the temperature range (560-580 Degree-Sign C), the relation between the fluxes emitted by the sources of Group-V and -III elements ( Less-Than-Or-Equivalent-To 1), and the order of layer growth for the production of the active region of a GaAs/InGaP laser heterostructure are determined experimentally. The active region is a GaAs{sub 0.75}Sb{sub 0.25}-In{sub 0.2}Ga{sub 0.8}As bilayer quantum well. For the structure, a 1075-nm electroluminescence signal attributed to indirect transitions between the valence band of the GaAs{sub 0.75}Sb{sub 0.25} layer and the conduction band of the In{sub 0.2}Ga{sub 0.8}As layer is observed. An increase in the continuous-wave pump current yields a decrease in the 1075-nm emission intensity and initiates stable lasing at a wavelength of 1022 nm at a threshold current density of 1.4 kA cm{sup -2} at room temperature. Lasing occurs at transitions direct in coordinate space.

  7. MS. CHERYL ZAHNISER (Chair) 5915 Beach Drive SW

    E-Print Network [OSTI]

    .com MRS. GAIL HAYES DAVIS MS `74 ArtEd; BS `69 ArtEd Executive Director (retired) Young Audiences.stangelandlandscape.com MR. DOUG STREETER Arch `80 Design Principal Perkins + Will 1221 Second Avenue, Ste. 200 Seattle, WA 98101 206.381.6007 doug.streeter@perkinswill.com www.perkinswill.com MS. JULIE STOTT B-IArch `77

  8. GRADUATE STUDENT HANDBOOK Vol. I. Master Programs (MS and ME)

    E-Print Network [OSTI]

    .2 Degree Requirements 3.2.1 MS and ME Degree Requirements in Civil Engineering and Environmental.1 Welcome Welcome to the graduate program of the Department of Civil and Environmental Engineering and Environmental Engineering: Master of Engineering (M.E.) in Civil Engineering Master of Science (M.S.) in Civil

  9. Ms. Maushumi, Head Mistress Babul Sarkar, Vice President

    E-Print Network [OSTI]

    Nahar, Sultana Nurun

    Ms. Maushumi, Head Mistress Babul Sarkar, Vice President Char Domdoama Primary School Vill: Char Razzaq-Shamsun Best Teacher Award and Abdul Awal Sarkar Best Student Awards in Char Domdoma Primary School Dear Ms. Maushumi and Mr. Sarkar, My proposal for the introduction of one teaching and three

  10. AlGaN/GaN HFET Single-Ended Frequency Doubler Younkyu Chung and Tatsuo Itoh

    E-Print Network [OSTI]

    Itoh, Tatsuo

    AlGaN/GaN HFET Single-Ended Frequency Doubler Younkyu Chung and Tatsuo Itoh Department-mail: ykchung@ee.ucla.edu Abstract - This paper presents the first single-ended AlGaN/GaN heterojunction field, respectively. For the frequency doubler with 1mm gate periphery AlGaN/GaN HFET, conversion gain of 0.17 d

  11. Materials Science and Engineering B59 (1999) 319322 Microcalorimetric absorption spectroscopy in GaNAlGaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    1999-01-01T23:59:59.000Z

    Microcalorimetric measurements of small absorption coefficients have been performed on thin GaN­AlGaN quantum wells in GaN­AlGaN quantum wells Axel Go¨ldner a, *, Axel Hoffmann a , Bernard Gil b , Pierre Lefebvre b at the energy of the GaN buffer and at the energy of the thick AlGaN barrier layers, we could also readily

  12. Al fraction induced effects on the capacitance characteristics -GaN/AlxGa1-xN IR detectors

    E-Print Network [OSTI]

    Dietz, Nikolaus

    substrate. As shown in Fig. 1(a), the device structures consist of a 0.2 m n+ -GaN top contact (emitter.1117/12.828156 Proc. of SPIE Vol. 7467 74670W-1 #12;(a) Sapphire Substrate n GaN Bottom Contact AlxGa1-xN Barrier n GaNAl fraction induced effects on the capacitance characteristics of n+ -GaN/AlxGa1-xN IR detectors

  13. Improvement of breakdown voltage in InGaP/InGaAs/GaAs heterostructure MESFETs for MMICs

    SciTech Connect (OSTI)

    Koh, Inoue; Yamane, Yasuro; Shiojima, Kenji [NTT LSI Lab., Kanagawa (Japan)] [and others

    1995-12-31T23:59:59.000Z

    This paper describes the trade-off between breakdown voltage and RF performance of InGaP/InGaAs/GaAs heterostructure MESFETs for power amplifiers and oscillators in multi-function MMICs in the millimeter-wave range. The authors successfully improved both gate-drain and drain-source breakdown voltages while maintaining excellent high-frequency performance by using a double-layered gate consisting of WSiN with different nitrogen contents, and by varying epitaxial layer thickness and implantation dose.

  14. Necessity of Ga prelayers in GaAs/Ge growth using gas-source molecular beam epitaxy

    E-Print Network [OSTI]

    in a highly defective GaAs layer.as5 Recently, InGaP light-emitting diodes have been fabricated on Si using

  15. Structural and optical properties of InGaN–GaN nanowire heterostructures grown by molecular beam epitaxy

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Limbach, F. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Gotschke, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Stoica, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Calarco, R. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Sutter, E. [Brookhaven National Lab., Upton, NY (United States); Ciston, J. [Brookhaven National Lab., Upton, NY (United States); Cusco, R. [Consell Superior d'Investigacions Cientifiques (CSIC), Barcelona (Spain); Artus, L. [Consell Superior d'Investigacions Cientifiques (CSIC), Barcelona (Spain); Kremling, S. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Hofling, S. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Worschech, L. [Univ. Wurzburg, Wilhelm Conrad Rontgen Research Centre Complex Matter Systems, Wurzburg (Germany); Grutzmacher, D. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jülich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany)

    2011-01-07T23:59:59.000Z

    InGaN/GaN nanowire (NW) heterostructures grown by plasma assisted molecular beam epitaxy were studied in comparison to their GaN and InGaN counterparts. The InGaN/GaN heterostructure NWs are composed of a GaN NW, a thin InGaN shell, and a multifaceted InGaN cap wrapping the top part of the GaN NW. High-resolution transmission electron microscopy (HRTEM) images taken from different parts of a InGaN/GaN NW show a wurtzite structure of the GaN core and the epitaxial InGaN shell around it, while additional crystallographic domains are observed whithin the InGaN cap region. Large changes in the lattice parameter along the wire, from pure GaN to higher In concentration demonstrate the successful growth of a complex InGaN/GaN NW heterostructure. Photoluminescence (PL) spectra of these heterostructure NW ensembles show rather broad and intense emission peak at 2.1 eV. However, ?-PL spectra measured on single NWs reveal a reduced broadening of the visible luminescence. The analysis of the longitudinal optical phonon Raman peak position and its shape reveal a variation in the In content between 20% and 30%, in agreement with the values estimated by PL and HRTEM investigations. The reported studies are important for understanding of the growth and properties of NW heterostructures suitable for applications in optoelectronics and photovoltaics.

  16. High-efficiency radiation-resistant InGaP/GaAs tandem solar cells

    SciTech Connect (OSTI)

    Takamoto, T. [Toyota Technological Inst., Tempaku, Nagoya (Japan); [Japan Energy Corp., Toda, Saitama (Japan); Yamaguchi, M.; Taylor, S.J. [Toyota Technological Inst., Tempaku, Nagoya (Japan); Ikeda, E.; Agui, T.; Kurita, H. [Japan Energy Corp., Toda, Saitama (Japan)

    1997-12-31T23:59:59.000Z

    A world-record efficiency of 26.9% (AM0, 28 C) has been obtained for InGaP/GaAs tandem solar cells fabricated by the MOCVD method. The radiation resistance of the InGaP/GaAs tandem solar cells has also been evaluated following 1 MeV electron irradiation. Degradation in the tandem cell performance has been confirmed to be mainly attributed to large degradation in the GaAs bottom cell, which features a highly doped base layer. Similar radiation-resistance with GaAs-on-Ge cells has been observed for the InGaP/GaAs tandem cell. However, some recovery of the tandem cell performance has been found due to minority-carrier injection under light illumination of forward bias, which causes defect annealing in InGaP cells. The optimal design of the InGaP base layer thickness for current matching at end of life (EOL) (after irradiation with 10{sup 15} electrons cm{sup {minus}2}) has been examined.

  17. Investigation of the metabolism of Substance-P at the blood-brain barrier using LC-MS/MS

    E-Print Network [OSTI]

    Chappa, Arvind K.; Cooper, Joshua D.; Audus, Kenneth L.; Lunte, Susan M.

    2007-01-01T23:59:59.000Z

    , the metabolism of SP was investigated using an in vitro model of the BBB and LC-MS/MS. Substance P metabolism was found to be non-saturable in the concentration range of 100 nM to 10 ?M, with approximately 70% of the peptide remaining intact after 5 hrs...

  18. Highly uniform, multi-stacked InGaAs/GaAs quantum dots embedded in a GaAs nanowire

    SciTech Connect (OSTI)

    Tatebayashi, J., E-mail: tatebaya@iis.u-tokyo.ac.jp; Ota, Y. [NanoQUINE, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Ishida, S.; Nishioka, M.; Iwamoto, S.; Arakawa, Y. [NanoQUINE, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan); Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2014-09-08T23:59:59.000Z

    We demonstrate a highly uniform, dense stack of In{sub 0.22}Ga{sub 0.78}As/GaAs quantum dot (QD) structures in a single GaAs nanowire (NW). The size (and hence emission energy) of individual QD is tuned by careful control of the growth conditions based on a diffusion model of morphological evolution of NWs and optical characterization. By carefully tailoring the emission energies of individual QD, dot-to-dot inhomogeneous broadening of QD stacks in a single NW can be as narrow as 9.3?meV. This method provides huge advantages over traditional QD stack using a strain-induced Stranski-Krastanow growth scheme. We show that it is possible to fabricate up to 200 uniform QDs in single GaAs NWs using this growth technique without degradation of the photoluminescence intensity.

  19. Strain induced variations in band offsets and built-in electric fields in InGaN/GaN multiple quantum wells

    E-Print Network [OSTI]

    Alpay, S. Pamir

    Strain induced variations in band offsets and built-in electric fields in InGaN/GaN multiple InxGa1-xN(InGaN)/GaN multilayers on the In composition and misfit strain. The results indicate that for non-polar m-plane configurations with ½1210InGaN//½1210GaN and ½0001InGaN//½0001GaN epitaxial

  20. Multi-bands photoconductive response in AlGaN/GaN multiple quantum wells

    SciTech Connect (OSTI)

    Chen, G.; Rong, X.; Xu, F. J.; Tang, N. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Wang, X. Q., E-mail: wangshi@pku.edu.cn; Shen, B., E-mail: bshen@pku.edu.cn [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter, Beijing (China); Fu, K.; Zhang, B. S. [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Ruoshui Road 398, 215123 Suzhou (China); Hashimoto, H.; Yoshikawa, A. [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)

    2014-04-28T23:59:59.000Z

    Based on the optical transitions among the quantum-confined electronic states in the conduction band, we have fabricated multi-bands AlGaN/GaN quantum well infrared photodetectors. Crack-free AlGaN/GaN multiple quantum wells (MQWs) with atomically sharp interfaces have been achieved by inserting an AlN interlayer, which releases most of the tensile strain in the MQWs grown on the GaN underlayer. With significant reduction of dark current by using thick AlGaN barriers, photoconductive responses are demonstrated due to intersubband transition in multiple regions with center wavelengths of 1.3, 2.3, and 4??m, which shows potential applications on near infrared detection.

  1. High-performance InGaP/GaAs pnp {delta}-doped heterojunction bipolar transistor

    SciTech Connect (OSTI)

    Tsai, J.-H. [National Kaohsiung Normal University, Department of Electronic Engineering (China)], E-mail: jhtsai@nknucc.nknu.edu.tw; Chiu, S.-Y.; Lour, W.-S. [National Taiwan Ocean University, Department of Electrical Engineering (China); Guo, D.-F. [Air Force Academy, Department of Electronic Engineering (China)

    2009-07-15T23:59:59.000Z

    In this article, a novel InGaP/GaAs pnp {delta}-doped heterojunction bipolar transistor is first demonstrated. Though the valence band discontinuity at InGaP/GaAs heterojunction is relatively large, the addition of a {delta}-doped sheet between two spacer layers at the emitter-base (E-B) junction effectively eliminates the potential spike and increases the confined barrier for electrons, simultaneously. Experimentally, a high current gain of 25 and a relatively low E-B offset voltage of 60 mV are achieved. The offset voltage is much smaller than the conventional InGaP/GaAs pnp HBT. The proposed device could be used for linear amplifiers and low-power complementary integrated circuit applications.

  2. Synthesis, morphology and optical properties of GaN and AlGaN semiconductor nanostructures

    SciTech Connect (OSTI)

    Kuppulingam, B., E-mail: drbaskar2009@gmail.com; Singh, Shubra, E-mail: drbaskar2009@gmail.com; Baskar, K., E-mail: drbaskar2009@gmail.com [Crystal Growth Centre, Anna University, Chennai-600025 (India)

    2014-04-24T23:59:59.000Z

    Hexagonal Gallium Nitride (GaN) and Aluminum Gallium Nitride (AlGaN) nanoparticles were synthesized by sol-gel method using Ethylene Diamine Tetra Acetic acid (EDTA) complex route. Powder X-ray diffraction (PXRD) analysis confirms the hexagonal wurtzite structure of GaN and Al{sub 0.25}Ga{sub 0.75}N nanoparticles. Surface morphology and elemental analysis were carried out by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray spectroscopy (EDX). The room temperature Photoluminescence (PL) study shows the near band edge emission for GaN at 3.35 eV and at 3.59 eV for AlGaN nanoparticles. The Aluminum (Al) composition of 20% has been obtained from PL emission around 345 nm.

  3. Effect of polarization on intersubband transition in AlGaN/GaN multiple quantum wells

    SciTech Connect (OSTI)

    Chen, G.; Li, Z. L.; Wang, X. Q.; Huang, C. C.; Rong, X.; Xu, F. J.; Tang, N.; Qin, Z. X.; Shen, B. [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)] [State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Sang, L. W.; Sumiya, M. [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)] [Optical and Electronic Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Chen, Y. H. [Laboratory of Semiconductor Material Science, Institute of Semiconductors, CAS, Beijing 100083 (China)] [Laboratory of Semiconductor Material Science, Institute of Semiconductors, CAS, Beijing 100083 (China); Ge, W. K. [Department of Physics, Tsinghua University, Beijing 100871 (China)] [Department of Physics, Tsinghua University, Beijing 100871 (China)

    2013-05-13T23:59:59.000Z

    Intersubband transitions (ISBT) of AlGaN/GaN multiple quantum wells (MQWs) with wavelength towards atmospheric window (3-5 {mu}m) have been investigated. A Ga-excess epitaxial method is used in the molecular beam epitaxy leading to ultra-sharp interface and negligible elements inter-diffusion. The absorption peak wavelength of the ISBT was successfully tuned in the range of 3-4 {mu}m by modifying the GaN well thickness from 2.8 to 5.5 nm. It was further found that the polarization charge density of the AlGaN/GaN MQWs was about -0.034 C/m{sup 2} which gave rise to blueshift of the ISBT wavelength and thus partially compensated its redshift with increasing well thickness.

  4. InGaN/GaN single-quantum-well microdisks

    SciTech Connect (OSTI)

    Hsu, Yu-Chi; Lo, Ikai; Shih, Cheng-Hung; Pang, Wen-Yuan; Hu, Chia-Hsuan; Wang, Ying-Chieh; Chou, Mitch M. C. [Department of Physics, Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

    2012-06-11T23:59:59.000Z

    We have grown In{sub x}Ga{sub 1-x}N/GaN quantum wells atop GaN microdisk with {gamma}-LiAlO{sub 2} substrate by using plasma-assisted molecular beam epitaxy. The structural and optical properties of the samples were analyzed by transmission electron microscopy, x-ray diffraction, cathodoluminescence, and photoluminescence measurements. Based on the measured results, we obtained the indium concentration of the In{sub x}Ga{sub 1-x}N/GaN single quantum well to be x = 0.25 with a band-gap energy of 2.31 eV, which is consistent with the bowing effect of bulk In{sub x}Ga{sub 1-x}N: E{sub g}(x) = [3.42 - x * 2.65 - x * (1 - x) * 2.4] eV.

  5. Atomic layer deposition of GaN using GaCl3 and NH3 Oh Hyun Kim, Dojun Kim, and Tim Andersona

    E-Print Network [OSTI]

    Anderson, Timothy J.

    be grown at lower temperature than by CVD. As example, ALD growth of device quality GaAs, GaP, and InGaP

  6. Characterization of the Human Pancreatic Islet Proteome by Two-Dimensional LC/MS/MS

    SciTech Connect (OSTI)

    Metz, Thomas O.; Jacobs, Jon M.; Gritsenko, Marina A.; Fontes, Ghislaine; Qian, Weijun; Camp, David G.; Poitout, Vincent J.; Smith, Richard D.

    2006-12-01T23:59:59.000Z

    Research to elucidate the pathogenesis of type 1 diabetes mellitus has traditionally focused on the genetic and immunological factors associated with the disease, and, until recently, has not considered the target cell. While there have been reports detailing proteomic analyses of established islet cell lines or isolated rodent islets, the information gained is not always easily extrapolated to humans. Therefore, extensive characterization of the human islet proteome could result in better understanding of islet biology and lead to more effective treatment strategies. We have applied a two-dimensional LC-MS/MS-based analysis to the characterization of the human islet proteome, resulting in the detection of 29,021 unique peptides corresponding to 4,925 proteins. As expected, major islet hormones (insulin, glucagon, somatostatin), beta-cell enriched secretory products (IAPP), ion channels (K-ATP channel), and transcription factors (PDX-1, Nkx 6.1, HNF-1 beta) were detected. In addition, significant proteome coverage of metabolic enzymes and cellular pathways was obtained, including the insulin signaling cascade and the MAP kinase, NF-??, and JAK/STAT pathways. This work represents the most extensive characterization of the human islet proteome to date and provides a peptide reference library that may be utilized in future studies of islet biology and type 1 diabetes.

  7. Dependence of the ground-state transition energy versus optical pumping in GaAsSb/InGaAs/GaAs heterostructures

    SciTech Connect (OSTI)

    Morozov, S. V.; Kryzhkov, D. I., E-mail: krizh@ipmras.ru; Aleshkin, V. Ya. [Institute for Physics of Microstructures, RAS, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Yablonsky, A. N.; Krasilnik, Z. F. [Institute for Physics of Microstructures, RAS, 603950 Nizhny Novgorod (Russian Federation); Zvonkov, B. N.; Vikhrova, O. V. [Physical-Technical Research Institute, Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation)

    2014-01-13T23:59:59.000Z

    In this work, we report on the time-resolved photoluminescence studies of a double quantum well In{sub 0.2}Ga{sub 0.8}As/GaAs{sub 0.8}Sb{sub 0.2}/GaAs heterostructure which, in contrast to the GaAsSb/GaAs structures, is expected to provide effective confinement of electrons due to additional InGaAs layer. The studies at 4.2?K have revealed a complicated nonmonotonic dependence of the ground-state transition energy on the concentration of nonequilibrium charge carriers in the quantum well. The effect observed in this work is important in terms of creating sources of radiation, including stimulated emission, on the basis of InGaAs/GaAsSb/GaAs structures.

  8. AlGaN/GaN field effect transistors for power electronics—Effect of finite GaN layer thickness on thermal characteristics

    SciTech Connect (OSTI)

    Hodges, C., E-mail: chris.hodges@bristol.ac.uk; Anaya Calvo, J.; Kuball, M. [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)] [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Stoffels, S.; Marcon, D. [IMEC, Kapeldreef 75, B3001 Leuven (Belgium)] [IMEC, Kapeldreef 75, B3001 Leuven (Belgium)

    2013-11-11T23:59:59.000Z

    AlGaN/GaN heterostructure field effect transistors with a 150?nm thick GaN channel within stacked Al{sub x}Ga{sub 1?x}N layers were investigated using Raman thermography. By fitting a thermal simulation to the measured temperatures, the thermal conductivity of the GaN channel was determined to be 60?W m{sup ?1} K{sup ?1}, over 50% less than typical GaN epilayers, causing an increased peak channel temperature. This agrees with a nanoscale model. A low thermal conductivity AlGaN buffer means the GaN spreads heat; its properties are important for device thermal characteristics. When designing power devices with thin GaN layers, as well as electrical considerations, the reduced channel thermal conductivity must be considered.

  9. InGaAsP/InGaP buried heterostructure lasers at 810 nm

    SciTech Connect (OSTI)

    Wakao, K.; Isozumi, S.; Nishi, H.; Ohsaka, S.

    1984-12-01T23:59:59.000Z

    InGaAsP/InGaP buried heterostructure lasers emitting at 810 nm have been grown on GaAs substrates using two-step liquid-phase epitaxy. A threshold current of 79 mA and an external differential quantum efficiency of 26% are obtained. Fundamental transverse mode operation up to 3 mW is achieved in the laser with the active region of 3.5 ..mu..m wide.

  10. Simplified 2DEG carrier concentration model for composite barrier AlGaN/GaN HEMT

    SciTech Connect (OSTI)

    Das, Palash, E-mail: d.palash@gmail.com; Biswas, Dhrubes, E-mail: d.palash@gmail.com [Indian Institute of Technology Kharagpur, Kharagpur - 721302, West Bengal (India)

    2014-04-24T23:59:59.000Z

    The self consistent solution of Schrodinger and Poisson equations is used along with the total charge depletion model and applied with a novel approach of composite AlGaN barrier based HEMT heterostructure. The solution leaded to a completely new analytical model for Fermi energy level vs. 2DEG carrier concentration. This was eventually used to demonstrate a new analytical model for the temperature dependent 2DEG carrier concentration in AlGaN/GaN HEMT.

  11. Ohmic contacts to n-GaSb

    E-Print Network [OSTI]

    Yang, Zhengchong

    1997-01-01T23:59:59.000Z

    In recent years, the Ill-V semiconductor GaSb and its ternary alloys containing antimony have exhibited interesting electrical and optical properties for device applications which include negative resistance tunnel devices, lasers, detectors and FET...

  12. The structure of GaAs/Si(211) heteroepitaxial layers

    SciTech Connect (OSTI)

    Liliental-Weber, Z.; Weber, E.R.; Washburn, J.; Liu, T.Y.; Kroemer, H.

    1985-05-01T23:59:59.000Z

    Gallium arsenide films grown on (211)Si by molecular-beam epitaxy have been investigated using transmission electron microscopy. The main defects observed in the alloy were of misfit dislocations, stacking faults, and microtwin lamellas. Silicon surface preparation was found to play an important role on the density of defects formed at the Si/GaAs interface. Two different types of strained-layer superlattices, InGaAs/InGaP and InGaAs/GaAs, were applied either directly to the Si substrate, to a graded layer (GaP-InGaP), or to a GaAs buffer layer to stop the defect propagation into the GaAs films. Applying InGaAs/GaAs instead of InGaAs/InGaP was found to be more effective in blocking defect propagation. In all cases of strained-layer superlattices investigated, dislocation propagation was stopped primarily at the top interface between the superlattice package and GaAs. Graded layers and unstrained AlGaAs/GaAs superlattices did not significantly block dislocations propagating from the interface with Si. Growing of a 50 nm GaAs buffer layer at 505/sup 0/C followed by 10 strained-layer superlattices of InGaAs/GaAs (5 nm each) resulted in the lowest dislocation density in the GaAs layer (approx.5 x 10/sup 7//cm/sup 2/) among the structures investigated. This value is comparable to the recently reported density of dislocations in the GaAs layers grown on (100)Si substrates. Applying three sets of the same strained layers decreased the density of dislocations an additional approx.2 to 3 times.

  13. Over 30{percent} efficient InGaP/GaAs tandem solar cells

    SciTech Connect (OSTI)

    Takamoto, T.; Ikeda, E.; Kurita, H. [Central Research Laboratory, Japan Energy Corporation, 3-17-35 Niizo-Minami, Toda, Saitama 335 (Japan)] [Central Research Laboratory, Japan Energy Corporation, 3-17-35 Niizo-Minami, Toda, Saitama 335 (Japan); Ohmori, M. [Japan Energy Research Center Company, Ltd., 1-11-9 Azabudai, Minato-ku, Tokyo 106 (Japan)] [Japan Energy Research Center Company, Ltd., 1-11-9 Azabudai, Minato-ku, Tokyo 106 (Japan)

    1997-01-01T23:59:59.000Z

    A two-terminal monolithic InGaP/GaAs tandem solar cell with a new efficiency record of 30.28{percent} is realized with a practical large area of 4 cm{sup 2} under one-sun air-mass 1.5 global illumination. We report improvements of the tandem cell performance by introducing a double-hetero (hereafter DH) structure InGaP tunnel junction, in which the InGaP layers are surrounded by high band gap AlInP barriers. The DH structure by AlInP barriers increase the peak current of InGaP tunnel junction. The AlInP barrier directly below the InGaP top cell, which takes the part of a back surface field (hereafter BSF) layer, is found to be considerably effective in reflecting minority carriers in the top cell. The AlInP BSF layer does not only form a high potential barrier but also prevents the diffusion of zinc from a high doped tunnel junction toward the top cell during epitaxial growth. Furthermore, an InGaP tunnel junction reduces the absorption loss, which exists in a GaAs tunnel junction, and increases the photogenerated current in the GaAs bottom cell. {copyright} {ital 1997 American Institute of Physics.}

  14. GaTe semiconductor for radiation detection

    DOE Patents [OSTI]

    Payne, Stephen A. (Castro Valley, CA); Burger, Arnold (Nashville, TN); Mandal, Krishna C. (Ashland, MA)

    2009-06-23T23:59:59.000Z

    GaTe semiconductor is used as a room-temperature radiation detector. GaTe has useful properties for radiation detectors: ideal bandgap, favorable mobilities, low melting point (no evaporation), non-hygroscopic nature, and availability of high-purity starting materials. The detector can be used, e.g., for detection of illicit nuclear weapons and radiological dispersed devices at ports of entry, in cities, and off shore and for determination of medical isotopes present in a patient.

  15. Probing temperature gradients within the GaN buffer layer of AlGaN/GaN high electron mobility transistors with Raman thermography

    SciTech Connect (OSTI)

    Hodges, C., E-mail: chris.hodges@bristol.ac.uk; Pomeroy, J.; Kuball, M. [H. H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2014-02-14T23:59:59.000Z

    We demonstrate the ability of confocal Raman thermography using a spatial filter and azimuthal polarization to probe vertical temperature gradients within the GaN buffer layer of operating AlGaN/GaN high electron mobility transistors. Temperature gradients in the GaN layer are measured by using offset focal planes to minimize the contribution from different regions of the GaN buffer. The measured temperature gradient is in good agreement with a thermal simulation treating the GaN thermal conductivity as homogeneous throughout the layer and including a low thermal conductivity nucleation layer to model the heat flow between the buffer and substrate.

  16. Thermoelectric effects in wurtzite GaN and AlxGa1-xN alloys and Alexander A. Balandin

    E-Print Network [OSTI]

    with the active thermoelectric cooling implemented on the same material system can improve the device performance, for the pro- posed cooling system should also be based on GaN. To real- ize this, the high-efficiency Ga,6 Great progress has been achieved in GaN-based microwave technology. GaN transistors with very high

  17. Journal of Crystal Growth 298 (2007) 272275 Dislocation analysis in homoepitaxial GaInN/GaN light emitting

    E-Print Network [OSTI]

    Wetzel, Christian M.

    2007-01-01T23:59:59.000Z

    of GaInN/GaN-based light emitting diodes (LED) on quasi-bulk GaN with an atomically flat polished were much improved. The optical output power of the light emitting diode increased by more than one. Cathodoluminescence; A1. Threading dislocation density; A2. Homoepitaxial growth; B1. GaInN; B3. Light emitting diode

  18. The Effect of the Thermal Boundary Resistance on Self-Heating of AlGaN/GaN HFETs

    E-Print Network [OSTI]

    The Effect of the Thermal Boundary Resistance on Self-Heating of AlGaN/GaN HFETs 1. Introduction, performance of these devices has been limited by self-heating [1] [6]. Thus, accurate modeling of heat diffusion and self-heating effects in AlGaN/GaN heterostructures and device optimization based

  19. InAsGaPInGaP high-temperature power Schottky rectifier and J. M. Woodall

    E-Print Network [OSTI]

    Woodall, Jerry M.

    °C. Further improvement of the thermal stability is expected to be achieved by reducing the diffusion is thought to be due to strong covalent bonding at the InAs/GaP interface. The InAs/GaP heterointerface effectively blocks impurity diffusion. Since InGaP is superior to GaP for high-power applica- tions, as shown

  20. GaAs-based self-aligned laser incorporating InGaP opto-electronic confinement layer

    E-Print Network [OSTI]

    GaAs-based self-aligned laser incorporating InGaP opto-electronic confinement layer K.M. Groom, B fabrication, is demonstrated. An n-doped InGaP layer is utilised for both electrical and optical confinement-doped InGaP current blocking layer that also provides optical confinement. This tech- nology relies

  1. GaN/ZnO and AlGaN/ZnO heterostructure LEDs: growth, fabrication, optical and electrical characterization

    E-Print Network [OSTI]

    Wetzel, Christian M.

    GaN/ZnO and AlGaN/ZnO heterostructure LEDs: growth, fabrication, optical and electrical 12180-3590, U.S.A. ABSTRACT The wide bandgap polar semiconductors GaN and ZnO and their related alloys fields, and surface terminations. With a small lattice mismatch of ~1.8 % between GaN and Zn

  2. Direct Evidence of Nanoscale Carrier Localization in InGaN/GaN Structures Grown on Si Substrates

    E-Print Network [OSTI]

    Nabben, Reinhard

    Direct Evidence of Nanoscale Carrier Localization in InGaN/GaN Structures Grown on Si Substrates: time-resolved photoluminescence, quantum dots, InGaN, Si substrate There exists a strong continuous expensive and are limited in size. Thus, heteroepitaxial growth of GaN on silicon substrates seems

  3. Inclined dislocation-pair relaxation mechanism in homoepitaxial green GaInN/GaN light-emitting diodes

    E-Print Network [OSTI]

    Wetzel, Christian M.

    -emitting diodes LEDs on low-defect density bulk GaN substrate, but not in green LEDs on sapphire substrate an ideal substrate for homoepitaxial growth. Here we study the microstructural properties of green GaInN/GaN-Koehler force10 resulting from a macroscopic relaxation of strain. II. CRYSTAL GROWTH c plane bulk GaN substrate

  4. Junction Temperature Measurements and Thermal Modeling of GaInN/GaN Quantum Well Light-Emitting Diodes

    E-Print Network [OSTI]

    Wetzel, Christian M.

    quantum well (QW) light-emitting diodes (LEDs) grown on sapphire and bulk GaN substrate by micro efficiency in dies grown on GaN substrates with a thermal resistance of 75 K/W. For dies on sapphire of GaN-based blue and green LEDs grown on sapphire and GaN substrates using micro-Raman spectroscopy

  5. Correlation between structural properties and optical amplification in InGaN/GaN heterostructures grown by molecular beam epitaxy

    E-Print Network [OSTI]

    Nabben, Reinhard

    . The lateral homogeneity can be drastically improved using a template of GaN grown on the sapphire substrate-grown heterostructures can drastically be reduced by using a template of MOVPE-GaN on the sapphire substrate, which leadsCorrelation between structural properties and optical amplification in InGaN/GaN heterostructures

  6. Magnetization relaxation in (Ga,Mn)As ferromagnetic semiconductors

    E-Print Network [OSTI]

    Sinova, Jairo; Jungwirth, T.; Liu, X.; Sasaki, Y.; Furdyna, JK; Atkinson, WA; MacDonald, AH.

    2004-01-01T23:59:59.000Z

    - ?As ferromagnetic semiconductors Furdyna,4,3 W. A. Atkinson,5 and A. H. MacDonald3 y, College Station, Texas 77843-4242, USA a? 10, 162 53 Praha 6, Czech Republic at Austin, Austin, Texas 78712-0264, USA Dame, Notre Dame, Indiana 46556, USA y...-quality samples, due to the coupling of the d-level local moments to 5 Donald, Phys. Rev. B 66, 012402 ~2002!; K.W. Edmonds, K.Y. Wang, R.P. Campion, A.C. Neumann, C.T. Foxon, B.L. Gal- lagher, and P.C. Main, Appl. Phys. Lett. 81, 3010 ~2002!. 8 and A. Fert...

  7. MS211 -CALCULO NUMERICO -1o semestre de 2008

    E-Print Network [OSTI]

    Gomes Ruggiero, Márcia A.

    MS211 - C´ALCULO NUM´ERICO - 1o semestre de 2008 (http://www.ime.unicamp.br/ms211) turma professor¸c~ao: o suporte computacional b´asico da disciplina ser´a o MatLab. BIBLIOGRAFIA · "C´alculo Num´erico¸c~ao, Editora Pearson, 1997. · "M´etodos Num´ericos", Maria Cristina Cunha, 2a edi¸c~ao, Editora da Unicamp

  8. MS211 -CALCULO NUMERICO -2o semestre de 2007

    E-Print Network [OSTI]

    Sussner, Peter

    MS211 - C´ALCULO NUM´ERICO - 2o semestre de 2007 (http://www.ime.unicamp.br/ms211) Turma Professor suporte computacional da disciplina ser´a o MatLab. BIBLIOGRAFIA · "C´alculo Num´erico - Aspectos Te Pearson, 1997. · "M´etodos Num´ericos", Maria Cristina Cunha, 2a edi¸c~ao, Editora da Unicamp, 2000

  9. Ultra-high frequency photoconductivity decay in GaAs/Ge/GaAs double heterostructure grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Hudait, M. K.; Zhu, Y. [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Johnston, S. W. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)] [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Maurya, D.; Priya, S. [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Umbel, R. [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)] [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2013-03-04T23:59:59.000Z

    GaAs/Ge/GaAs double heterostructures (DHs) were grown in-situ using two separate molecular beam epitaxy chambers. High-resolution x-ray rocking curve demonstrates a high-quality GaAs/Ge/GaAs heterostructure by observing Pendelloesung oscillations. The kinetics of the carrier recombination in Ge/GaAs DHs were investigated using photoconductivity decay measurements by the incidence excitation from the front and back side of 15 nm GaAs/100 nm Ge/0.5 {mu}m GaAs/(100)GaAs substrate structure. High-minority carrier lifetimes of 1.06-1.17 {mu}s were measured when excited from the front or from the back of the Ge epitaxial layer, suggests equivalent interface quality of GaAs/Ge and Ge/GaAs. Wavelength-dependent minority carrier recombination properties are explained by the wavelength-dependent absorption coefficient of Ge.

  10. Metastable states in InGaN/GaN MQW structures doped with Sm, Eu, and Eu + Sm

    SciTech Connect (OSTI)

    Mezdrogina, M. M., E-mail: Margaret.M@mail.ioffe.ru [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kozhanova, Yu. V. [St. Petersburg State Polytechnical University (Russian Federation)

    2013-04-15T23:59:59.000Z

    Measurements of the microphotoluminescence (microPL) spectra of InGaN/GaN:Sm and InGaN/GaN:Eu quantum well (QW) structures show that the action of a magnetic field gives rise to Van Vleck paramagnetism for Eu{sup 3+} and Sm{sup 3+}. The macrophotoluminescence (macroPL) spectra recorded after measuring the microPL spectra of InGaN/GaN QW structures doped with Sm or Eu + Sm at a high excitation level (>10{sup 23} photons cm{sup -2} s{sup -1}) in magnetic fields contain no QW emission lines which are present in the macroPL spectra recorded before these microPL measurements. This is indicative of the presence of photoinduced defects. Annealing of the InGaN/GaN:Sm and InGaN/GaN:(Eu + Sm) structures reduces the concentration of photoinduced defects.

  11. An LC-IMS-MS Platform Providing Increased Dynamic Range for High...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    a tryptic digest of mouse blood plasma and analyzed with both a LC-Linear Ion Trap Fourier Transform (FT) MS and LC-IMS-TOF MS. The LC-FT MS detected thirteen out of the twenty...

  12. Gas-source molecular beam epitaxial growth and characterization of the (Al,In,Ga)NP/GaP material system and Its applications to light-emitting diodes

    E-Print Network [OSTI]

    Odnoblyudov, Vladimir

    2006-01-01T23:59:59.000Z

    on metamorphic growth of InGaP layers on GaP substrates, astemperature amber photoluminescence from InGaP QWs, grownon a metamorphic InGaP layer. References: Fred Shubert E. ,

  13. InGaN/GaN tunnel junctions for hole injection in GaN light emitting diodes

    SciTech Connect (OSTI)

    Krishnamoorthy, Sriram, E-mail: krishnamoorthy.13@osu.edu, E-mail: rajan@ece.osu.edu; Akyol, Fatih [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Rajan, Siddharth, E-mail: krishnamoorthy.13@osu.edu, E-mail: rajan@ece.osu.edu [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2014-10-06T23:59:59.000Z

    InGaN/GaN tunnel junction contacts were grown using plasma assisted molecular beam epitaxy (MBE) on top of a metal-organic chemical vapor deposition (MOCVD)-grown InGaN/GaN blue (450?nm) light emitting diode. A voltage drop of 5.3?V at 100?mA, forward resistance of 2 × 10{sup ?2} ? cm{sup 2}, and a higher light output power compared to the reference light emitting diodes (LED) with semi-transparent p-contacts were measured in the tunnel junction LED (TJLED). A forward resistance of 5?×?10{sup ?4} ? cm{sup 2} was measured in a GaN PN junction with the identical tunnel junction contact as the TJLED, grown completely by MBE. The depletion region due to the impurities at the regrowth interface between the MBE tunnel junction and the MOCVD-grown LED was hence found to limit the forward resistance measured in the TJLED.

  14. ccsd-00000821(version1):6Nov2003 Alloy effects in Ga1-xInxN/GaN heterostructures

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ccsd-00000821(version1):6Nov2003 Alloy effects in Ga1-xInxN/GaN heterostructures Duc-Phuong Nguyen, France We show that the large band offsets between GaN and InN and the heavy carrier effec- tive masses preclude the use of the Virtual Crystal Approximation to describe the electronic structure of Ga1-xInxN/GaN

  15. DESIGN, GROWTH, FABRICATION AND CHARACTERIZATION OF HIGH-BAND GAP InGaN/GaN SOLAR CELLS

    E-Print Network [OSTI]

    Honsberg, Christiana

    DESIGN, GROWTH, FABRICATION AND CHARACTERIZATION OF HIGH-BAND GAP InGaN/GaN SOLAR CELLS Omkar Jani1 with a band gap of 2.4 eV or greater. InxGa1-xN is one of a few alloys that can meet this key requirement. InGaN.4 eV. InGaN has the appropriate optical properties and has been well demonstrated for light

  16. AlGaN/GaN MIS-HEMT Gate Structure Improvement Using Al2O3 Deposited by PEALD

    E-Print Network [OSTI]

    Boyer, Edmond

    AlGaN/GaN MIS-HEMT Gate Structure Improvement Using Al2O3 Deposited by PEALD R. Meunier1 , A, 38054 Grenoble Cedex 9, France 2 LAAS-CNRS, 7 Avenue du Colonel Roche, 31400 Toulouse, France AlGaN /GaN behavior. Those trapped charges can be associated to the carbon contamination of the AlGaN surface

  17. Emission mechanisms of bulk GaN and InGaN quantum wells prepared by lateral epitaxial overgrowth

    E-Print Network [OSTI]

    Bowers, John

    Emission mechanisms of bulk GaN and InGaN quantum wells prepared by lateral epitaxial overgrowth S for publication 5 January 1999 The emission mechanisms of bulk GaN and InGaN quantum wells QWs were studied suggest that TDs simply reduce the net volume of light-emitting area. This effect is less pronounced in InGaN

  18. Comparison of strong coupling regimes in bulk GaAs, GaN and ZnO semiconductor microcavities

    E-Print Network [OSTI]

    Boyer, Edmond

    , transmission and absorption spectra of bulk GaAs, GaN and ZnO microcavities, in order to compareComparison of strong coupling regimes in bulk GaAs, GaN and ZnO semiconductor microcavities SAs and GaN microcavities. PACS numbers: 78.67.-n, 71.36.+c, 78.20.Ci, 78.55.Cr, 78.55.Et Keywords: polariton

  19. Near ultraviolet emission from nonpolar cubic AlxGa1-xN/GaN quantum wells

    E-Print Network [OSTI]

    As, Donat Josef

    molecular beam epitaxy on free standing 3C-SiC 001 substrates. During growth of Al0.15Ga0.85N/GaN quantum growth of the quantum structures an 800 nm thick GaN buffer layer was deposited on the 3C-SiC substrate. The buffer and the c-AlGaN/GaN quantum wells were grown at a substrate temperature of 720 °C. The layers were

  20. Nanoair-bridged lateral overgrowth of GaN on ordered nanoporous GaN template

    SciTech Connect (OSTI)

    Wang, Y.D.; Zang, K.Y.; Chua, S.J.; Tripathy, S.; Chen, P.; Fonstad, C.G. [Singapore-MIT Alliance, E4-04-10, 4 Engineering Drive 3, Singapore 117576 (Singapore) and Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, 2 Engineering Drive 3, Singapore 117576 (Singapore); Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602 (Singapore); Department of Electrical and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2005-12-19T23:59:59.000Z

    We report the growth of high-quality GaN epilayers on an ordered nanoporous GaN template by metalorganic chemical vapor deposition. The nanopores in GaN template were created by inductively coupled plasma etching using anodic aluminum oxide film as an etch mask. The average pore diameter and interpore distance is about 65 and 110 nm, respectively. Subsequent overgrowth of GaN first begins at the GaN crystallite surface between the pores, and then air-bridge-mediated lateral overgrowth leads to the formation of the continuous layer. Microphotoluminescence and micro-Raman measurements show improved optical properties and significant strain relaxation in the overgrown layer when compared to GaN layer of same thickness simultaneously grown on sapphire without any template. Similar to conventional epitaxial lateral overgrown GaN, such overgrown GaN on a nanopatterned surface would also serve as a template for the growth of ultraviolet-visible light-emitting III-nitride devices.

  1. AlGaN/GaN HEMT With 300-GHz fmax

    E-Print Network [OSTI]

    Chung, Jinwook W.

    We report on a gate-recessed AlGaN/GaN high-electron mobility transistor (HEMT) on a SiC substrate with a record power-gain cutoff frequency (f[subscript max]). To achieve this high f[subscript max], we combined a low-damage ...

  2. Gate-First AlGaN/GaN HEMT Technology for High-Frequency Applications

    E-Print Network [OSTI]

    Piner, Edwin L.

    This letter describes a gate-first AlGaN/GaN high-electron mobility transistor (HEMT) with a W/high-k dielectric gate stack. In this new fabrication technology, the gate stack is deposited before the ohmic contacts, and ...

  3. High Indium Concentration InGaN/GaN Grown on Sapphire Substrate by MOCVD

    E-Print Network [OSTI]

    Hartono, Haryono

    The InGaN system provides the opportunity to fabricate light emitting devices over the whole visible and ultraviolet spectrum due to band-gap energies E[subscript g] varying between 3.42 eV for GaN and 1.89 eV for InN. ...

  4. Schottky-Drain Technology for AlGaN/GaN High-Electron Mobility Transistors

    E-Print Network [OSTI]

    Lu, Bin

    In this letter, we demonstrate 27% improvement in the buffer breakdown voltage of AlGaN/GaN high-electron mobility transistors (HEMTs) grown on Si substrate by using a new Schottky-drain contact technology. Schottky-drain ...

  5. Investigation of Strain in AlGaN/GaN Multi Quantum Wells by Complementary Techniques

    SciTech Connect (OSTI)

    Devaraju, G.; Sathish, N.; Pathak, A. P. [School of Physics, University of Hyderabad, Central University (P.0), Hyderabad 500 046 (India); Dhamodaran, S. [Department of Physics, Indian Institute of Technology, IIT P O, Kanpur UP 208016 (India); Gaca, J.; Wojcik, M. [Institute of Electronic Materials Technology, 01-919 Warsaw, ul. Wolczynska 133 (Poland); Turos, A. [Institute of Electronic Materials Technology, 01-919 Warsaw, ul. Wolczynska 133 (Poland); Soltan Institute for Nuclear Studies, Swierk/Otwock, Warsaw (Poland); Arora, B. M. [Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005 (India)

    2009-03-10T23:59:59.000Z

    Al{sub 0.49}Ga{sub 0.51}N(12 nm)/GaN (13 nm) Multi Quantum Wells of 15 periods are grown on sapphire by MOCVD technique. GaN/AlN, each of thickness 200 nm and 20 nm respectively, are used as buffer layers between substrate and epilayer to incorporate the strain in epilayers. It is a well established technique to engineer the band gap in Al{sub x}Ga{sub 1-x}N by adjusting alloy composition. These samples are used in visible and UV light emitters. In the present study, we employ a photoluminescence technique to estimate the composition and luminescence peak positions of AlGaN and GaN. Crystallinity and quality of interfaces have been studied by Rocking curve scan. The Threading Dislocations formed at the GaN buffer layer travel across the entire layers to the surface to form good quality films. Photo-luminescence results show a very sharp GaN peak at 3.4 eV, as observed and reported by others, which shows that samples are free from point defects.

  6. Gallium surface diffusion on GaAs (001) surfaces measured by crystallization dynamics of Ga droplets

    SciTech Connect (OSTI)

    Bietti, Sergio, E-mail: sergio.bietti@mater.unimib.it; Somaschini, Claudio; Esposito, Luca; Sanguinetti, Stefano [L–NESS and Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 55, I–20125 Milano (Italy); Fedorov, Alexey [L–NESS and CNR–IFN, via Anzani 42, I-22100 Como (Italy)

    2014-09-21T23:59:59.000Z

    We present accurate measurements of Ga cation surface diffusion on GaAs surfaces. The measurement method relies on atomic force microscopy measurement of the morphology of nano–disks that evolve, under group V supply, from nanoscale group III droplets, earlier deposited on the substrate surface. The dependence of the radius of such nano-droplets on crystallization conditions gives direct access to Ga diffusion length. We found an activation energy for Ga on GaAs(001) diffusion E{sub A}=1.31±0.15 eV, a diffusivity prefactor of D{sub 0}?=?0.53(×2.1±1) cm{sup 2} s{sup ?1} that we compare with the values present in literature. The obtained results permit to better understand the fundamental physics governing the motion of group III ad–atoms on III–V crystal surfaces and the fabrication of designable nanostructures.

  7. Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices

    SciTech Connect (OSTI)

    Wang, C.A.; Choi, H.K.; Turner, G.W.; Spears, D.L.; Manfra, M.J. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

    1997-05-01T23:59:59.000Z

    The materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for lattice-matched thermophotovoltaic (TPV) devices is reported. Epilayers with cutoff wavelength 2--2.4 {micro}m at room temperature and lattice-matched to GaSb substrates were grown by both low-pressure organometallic vapor phase epitaxy and molecular beam epitaxy. These layers exhibit high optical and structural quality. For demonstrating lattice-matched thermophotovoltaic devices, p- and n-type doping studies were performed. Several TPV device structures were investigated, with variations in the base/emitter thicknesses and the incorporation of a high bandgap GaSb or AlGaAsSb window layer. Significant improvement in the external quantum efficiency is observed for devices with an AlGaAsSb window layer compared to those without one.

  8. Green cubic GaInN/GaN light-emitting diode on microstructured silicon (100)

    SciTech Connect (OSTI)

    Stark, Christoph J. M.; Detchprohm, Theeradetch; Wetzel, Christian, E-mail: wetzel@ieee.org [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States) [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Future Chips Constellation, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180 (United States); Lee, S. C.; Brueck, S. R. J. [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States)] [Department of Electrical and Computer Engineering and Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico 87106 (United States); Jiang, Y.-B. [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)] [Department of Earth and Planetary Science, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2013-12-02T23:59:59.000Z

    GaInN/GaN light-emitting diodes free of piezoelectric polarization were prepared on standard electronic-grade Si(100) substrates. Micro-stripes of GaN and GaInN/GaN quantum wells in the cubic crystal structure were grown on intersecting (111) planes of microscale V-grooved Si in metal-organic vapor phase epitaxy, covering over 50% of the wafer surface area. Crystal phases were identified in electron back-scattering diffraction. A cross-sectional analysis reveals a cubic structure virtually free of line defects. Electroluminescence over 20 to 100??A is found fixed at 487?nm (peak), 516?nm (dominant). Such structures therefore should allow higher efficiency, wavelength-stable light emitters throughout the visible spectrum.

  9. Large internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko, Gerald Hnig, Christian Kindel, Sven Rodt, Andr Strittmatter et al.

    E-Print Network [OSTI]

    Nabben, Reinhard

    Large internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko, Gerald Hönig, Christian transitions in wurtzite InGaN/GaN coupled quantum dot nanowire heterostructures with polarization internal dipole moment in InGaN/GaN quantum dots Irina A. Ostapenko,a Gerald Hönig, Christian Kindel, Sven

  10. Investigation of large Stark shifts in InGaN/GaN multiple quantum wells Guibao Xu, Guan Sun, Yujie J. Ding, Hongping Zhao, Guangyu Liu et al.

    E-Print Network [OSTI]

    Gilchrist, James F.

    Investigation of large Stark shifts in InGaN/GaN multiple quantum wells Guibao Xu, Guan Sun, Yujie overgrowth on residual strain and In incorporation in a-plane InGaN/GaN quantum wells on r- sapphire substrates J. Appl. Phys. 113, 023506 (2013) Anisotropic lattice relaxation in non-c-plane InGaN/GaN multiple

  11. Quantum confinement in GaP nanoclusters

    SciTech Connect (OSTI)

    Laurich, B.K.; Smith, D.C.; Healy, M.D.

    1994-06-01T23:59:59.000Z

    We have prepared GaP and GaAs nanoclusters from organometallic condensation reactions of E[Si(ChH{sub 3})3]3 (E = P, As) and GaCl{sub 3}. The size of the as synthesized clusters is 10 {Angstrom} to 15 {Angstrom}. Larger clusters of 20 {Angstrom} to 30 {Angstrom} size were obtained by thermal annealing of the as grown material. X-ray diffraction and transmission electron microscopy confirm the high crystalline quality. A lattice contraction of 6.7% could be seen for 10 {Angstrom} sized GaAs clusters. The clusters are nearly spherical in shape. Optical absorption spectra show a distinct line which can be assigned to the fundamental transition of the quantum confined electronic state. The measured blue shift, with respect to the GaP bulk absorption edge is 0.53 eV. As the cluster is smaller than the exciton radius, we can calculate the cluster size from this blue shift and obtain 20.2 {Angstrom}, consistent with the results from X-ray diffraction of 19.5 {Angstrom} for the same sample.

  12. UID-GaN doping1016 cm-3 2 m 5 m2 m

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    2 µm Drain Silicon UID-GaN ­ doping1016 cm-3 1.1 µm 2 µm GateSource 2 µm 5 µm2 µm AirAir Al0.25GaN ­ doping1015 cm-3 30 nm Drain Silicon UID-GaN P-GaNSource AirAir AlxGaN Drain Silicon UID-GaN GateSource AirAir AlxGaN Gate (a) (b) (c) Drain Silicon UID-GaN P-GaNSource AirAir AlxGaN Gate (d) P-GaN P-GaN 30

  13. LATA KY WEA-2012-01

    Energy Savers [EERE]

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directed offOCHCO2:Introduction to Energy PerformanceJohn CymbalskyKristina Johnson About Us Dr.TRIBALLANL

  14. Carrier capture dynamics of single InGaAs/GaAs quantum-dot layers

    SciTech Connect (OSTI)

    Chauhan, K. N.; Riffe, D. M.; Everett, E. A.; Kim, D. J.; Yang, H. [Physics Department, Utah State University, Logan, Utah 84322-4415 (United States)] [Physics Department, Utah State University, Logan, Utah 84322-4415 (United States); Shen, F. K. [Center for Surface Analysis and Applications, Utah State University, Logan, Utah 84322-4415 (United States)] [Center for Surface Analysis and Applications, Utah State University, Logan, Utah 84322-4415 (United States)

    2013-05-28T23:59:59.000Z

    Using 800 nm, 25-fs pulses from a mode locked Ti:Al{sub 2}O{sub 3} laser, we have measured the ultrafast optical reflectivity of MBE-grown, single-layer In{sub 0.4}Ga{sub 0.6}As/GaAs quantum-dot (QD) samples. The QDs are formed via two-stage Stranski-Krastanov growth: following initial InGaAs deposition at a relatively low temperature, self assembly of the QDs occurs during a subsequent higher temperature anneal. The capture times for free carriers excited in the surrounding GaAs (barrier layer) are as short as 140 fs, indicating capture efficiencies for the InGaAs quantum layer approaching 1. The capture rates are positively correlated with initial InGaAs thickness and annealing temperature. With increasing excited carrier density, the capture rate decreases; this slowing of the dynamics is attributed to Pauli state blocking within the InGaAs quantum layer.

  15. Epitaxial GaN films by hyperthermal ion-beam nitridation of Ga droplets

    SciTech Connect (OSTI)

    Gerlach, J. W.; Ivanov, T.; Neumann, L.; Hoeche, Th.; Hirsch, D.; Rauschenbach, B. [Leibniz-Institut fuer Oberflaechenmodifizierung (IOM), D-04318 Leipzig (Germany)

    2012-06-01T23:59:59.000Z

    Epitaxial GaN film formation on bare 6H-SiC(0001) substrates via the process of transformation of Ga droplets into a thin GaN film by applying hyperthermal nitrogen ions is investigated. Pre-deposited Ga atoms in well defined amounts form large droplets on the substrate surface which are subsequently nitridated at a substrate temperature of 630 Degree-Sign C by a low-energy nitrogen ion beam from a constricted glow-discharge ion source. The Ga deposition and ion-beam nitridation process steps are monitored in situ by reflection high-energy electron diffraction. Ex situ characterization by x-ray diffraction and reflectivity techniques, Rutherford backscattering spectrometry, and electron microscopy shows that the thickness of the resulting GaN films depends on the various amounts of pre-deposited gallium. The films are epitaxial to the substrate, exhibit a mosaic like, smooth surface topography and consist of coalesced large domains of low defect density. Possible transport mechanisms of reactive nitrogen species during hyperthermal nitridation are discussed and the formation of GaN films by an ion-beam assisted process is explained.

  16. GaAs photoconductive semiconductor switch

    DOE Patents [OSTI]

    Loubriel, G.M.; Baca, A.G.; Zutavern, F.J.

    1998-09-08T23:59:59.000Z

    A high gain, optically triggered, photoconductive semiconductor switch (PCSS) implemented in GaAs as a reverse-biased pin structure with a passivation layer above the intrinsic GaAs substrate in the gap between the two electrodes of the device is disclosed. The reverse-biased configuration in combination with the addition of the passivation layer greatly reduces surface current leakage that has been a problem for prior PCSS devices and enables employment of the much less expensive and more reliable DC charging systems instead of the pulsed charging systems that needed to be used with prior PCSS devices. 5 figs.

  17. GaAs photoconductive semiconductor switch

    DOE Patents [OSTI]

    Loubriel, Guillermo M. (Sandia Park, NM); Baca, Albert G. (Albuquerque, NM); Zutavern, Fred J. (Albuquerque, NM)

    1998-01-01T23:59:59.000Z

    A high gain, optically triggered, photoconductive semiconductor switch (PCSS) implemented in GaAs as a reverse-biased pin structure with a passivation layer above the intrinsic GaAs substrate in the gap between the two electrodes of the device. The reverse-biased configuration in combination with the addition of the passivation layer greatly reduces surface current leakage that has been a problem for prior PCSS devices and enables employment of the much less expensive and more reliable DC charging systems instead of the pulsed charging systems that needed to be used with prior PCSS devices.

  18. GaN: Defect and Device Issues

    SciTech Connect (OSTI)

    Pearton, S.J.; Ren, F.; Shul, R.J.; Zolper, J.C.

    1998-11-09T23:59:59.000Z

    The role of extended and point defects, and key impurities such as C, O and H, on the electrical and optical properties of GaN is reviewed. Recent progress in the development of high reliability contacts, thermal processing, dry and wet etching techniques, implantation doping and isolation and gate insulator technology is detailed. Finally, the performance of GaN-based electronic and photonic devices such as field effect transistors, UV detectors, laser diodes and light-emitting diodes is covered, along with the influence of process-induced or grown-in defects and impurities on the device physics.

  19. MS17AM LEAK CHECKER The MS17AM is a manual valve version of the MS17AB. Since it is a manual unit, some care must be

    E-Print Network [OSTI]

    Massey, Thomas N.

    MS17AM LEAK CHECKER The MS17AM is a manual valve version of the MS17AB. Since it is a manual unit, some care must be exercised in the sequencing of the valves. The most important things to remember are that during normal leak testing: 1. The THROTTLE VALVE is NEVER opened unless the ROUGH VALVE has been

  20. High-temperature molecular beam epitaxial growth of AlGaN/GaN on GaN templates with reduced interface impurity levels

    SciTech Connect (OSTI)

    Koblmueller, G. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Walter Schottky Institut, Technische Universitaet Muenchen, D-85748 Garching (Germany); Chu, R. M.; Raman, A.; Mishra, U. K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Speck, J. S. [Department of Materials, University of California, Santa Barbara, California 93106 (United States)

    2010-02-15T23:59:59.000Z

    We present combined in situ thermal cleaning and intentional doping strategies near the substrate regrowth interface to produce high-quality AlGaN/GaN high electron mobility transistors on semi-insulating (0001) GaN templates with low interfacial impurity concentrations and low buffer leakage. By exposing the GaN templates to an optimized thermal dissociation step in the plasma-assisted molecular beam epitaxy environment, oxygen, carbon, and, to lesser extent, Si impurities were effectively removed from the regrowth interface under preservation of good interface quality. Residual Si was further compensated by C-doped GaN via CBr{sub 4} to yield highly resistive GaN buffer layers. Improved N-rich growth conditions at high growth temperatures were then utilized for subsequent growth of the AlGaN/GaN device structure, yielding smooth surface morphologies and low residual oxygen concentration with large insensitivity to the (Al+Ga)N flux ratio. Room temperature electron mobilities of the two-dimensional electron gas at the AlGaN/GaN interface exceeded >1750 cm{sup 2}/V s and the dc drain current reached {approx}1.1 A/mm at a +1 V bias, demonstrating the effectiveness of the applied methods.

  1. Defect studies in low-temperature-grown GaAs

    SciTech Connect (OSTI)

    Bliss, D.E.

    1992-11-01T23:59:59.000Z

    High content of excess As is incorporated in GaAs grown by low-temperature molecular-beam-epitaxy (LTMBE). The excess As exists primarily as As antisite defects AsGa and a lesser extent of gallium vacancies V[sub Ga]. The neutral AsGa-related defects were measured by infrared absorption at 1[mu]m. Gallium vacancies, V[sub Ga], was investigated by slow positron annihilation. Dependence of defect contents on doping was studied by Si and Be dopants. No free carriers are generated by n-type or p-type doping up to 10[sup 19] cm[sup [minus]3] Si or Be. Raman data indicate Be occupies Ga substitutional sites but Si atom is not substitutional. Si induces more As[sub Ga] in the layer. As As[sub Ga] increases, photoquenchable As[sub Ga] decreases. Fraction of photoquenchable defects correlates to defects within 3 nearest neighbor separations disrupting the metastability. Annealing reduces neutral As[sub Ga] content around 500C, similar to irradiation damaged and plastically deformed Ga[sub As], as opposed to bulk grown GaAs in which As[sub Ga]-related defects are stable up to 1100C. The lower temperature defect removal is due to V[sub Ga] enhanced diffusion of As[sub Ga] to As precipitates. The supersaturated V[sub GA] and also decreases during annealing. Annealing kinetics for As[sub Ga]-related defects gives 2.0 [plus minus] 0.3 eV and 1.5 [plus minus] 0.3 eV migration enthalpies for the As[sub Ga] and V[sub Ga]. This represents the difference between Ga and As atoms hopping into the vacancy. The non-photoquenchable As[sub Ga]-related defects anneal with an activation energy of 1.1 [plus minus] 0.3eV. Be acceptors can be activated by 800C annealing. Temperature difference between defect annealing and Be activation formation of As[sub Ga]-Be[sub Ga] pairs. Si donors can only be partially activated.

  2. PHYSICAL REVIEW B 85, 045319 (2012) Photoluminescence from In0.5Ga0.5As/GaP quantum dots coupled to photonic crystal cavities

    E-Print Network [OSTI]

    Vuckovic, Jelena

    2012-01-01T23:59:59.000Z

    in materials systems, including InP/InGaP,6­9 InP/GaP,10,11 InP/AlGaInP,12,13 GaInP/GaP,14 InAs/GaP,15 and Al have been observed only in the InP/InGaP and InP/AlGaInP systems. GaP-based materials, by contrastP compared to InGaP is preferable for on-chip frequency downconversion to telecom wavelengths. Recently,17

  3. Optical spectroscopy of quantum confined states in GaAs/AlGaAs quantum well tubes

    SciTech Connect (OSTI)

    Shi, Teng; Fickenscher, Melodie; Smith, Leigh; Jackson, Howard [Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States); Yarrison-Rice, Jan [Department of Physics, Miami University, Oxford, OH 45056 (United States); Gao, Qiang; Tan, Hoe; Jagadish, Chennupati [Department of Electronic Materials and Engineering, Australian National University, Canberra, ACT 0200 (Australia); Etheridge, Joanne [Monash Centre for Electron Microscopy, Monash University, Victoria, 3800 (Australia); Wong, Bryan M. [Materials Chemistry Department, Sandia National Laboratories, Livermore, CA 94551 (United States)

    2013-12-04T23:59:59.000Z

    We have investigated the quantum confinement of electronic states in GaAs/Al{sub x}Ga{sub 1?x}As nanowire heterostructures which contain radial GaAs quantum wells of either 4nm or 8nm. Photoluminescence and photoluminescence excitation spectroscopy are performed on single nanowires. We observed emission and excitation of electron and hole confined states. Numerical calculations of the quantum confined states using the detailed structural information on the quantum well tubes show excellent agreement with these optical results.

  4. Strain-induced fundamental optical transition in (In,Ga)As/GaP quantum dots

    SciTech Connect (OSTI)

    Robert, C., E-mail: cedric.robert@insa-rennes.fr, E-mail: cedric.robert@tyndall.ie; Pedesseau, L.; Cornet, C.; Jancu, J.-M.; Even, J.; Durand, O. [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France)] [Université Européenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Coësmes, 35708 Rennes (France); Nestoklon, M. O. [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)] [Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation); Pereira da Silva, K. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Departamento de Física, Universidade Federal do Ceará, P.O. Box 6030, Fortaleza–CE, 60455-970 (Brazil); Alonso, M. I. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain)] [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Goñi, A. R. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); ICREA, Passeig Lluís Companys 23, 08010 Barcelona (Spain); Turban, P. [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)] [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Université de Rennes 1, F-35042 Rennes Cedex (France)

    2014-01-06T23:59:59.000Z

    The nature of the ground optical transition in an (In,Ga)As/GaP quantum dot is thoroughly investigated through a million atoms supercell tight-binding simulation. Precise quantum dot morphology is deduced from previously reported scanning-tunneling-microscopy images. The strain field is calculated with the valence force field method and has a strong influence on the confinement potentials, principally, for the conduction band states. Indeed, the wavefunction of the ground electron state is spatially confined in the GaP matrix, close to the dot apex, in a large tensile strain region, having mainly Xz character. Photoluminescence experiments under hydrostatic pressure strongly support the theoretical conclusions.

  5. Midinfrared intersubband absorption in GaN/AlGaN superlattices on Si(111) templates

    SciTech Connect (OSTI)

    Kandaswamy, P. K.; Monroy, E. [CEA/CNRS group 'Nanophysique et semiconducteurs', INAC/SP2M/NPSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Machhadani, H.; Sakr, S.; Tchernycheva, M.; Julien, F. H. [Photis, Institut d'Electronique Fondamentale, Universite Paris-Sud, 91405 Orsay Cedex (France); Bougerol, C. [CEA/CNRS group 'Nanophysique et semiconducteurs', Institut Neel, 25 rue des Martyrs, 38042 Grenoble Cedex 9 (France)

    2009-10-05T23:59:59.000Z

    We report on the observation of midinfrared intersubband absorption in Si-doped GaN/AlGaN superlattices grown by plasma-assisted molecular-beam epitaxy on semi-insulating GaN-on-Si(111) templates. TM-polarized absorption attributed to transition between the first two electronic levels in the quantum wells peaked in the range from 2 to 9 {mu}m. The relative spectral width remains around 20% in the whole midinfrared spectral range. Doping is predicted to have a large influence on the intersubband absorption energy due to screening of polarization-induced internal electric field.

  6. Fast and accurate database searches with MS-GF+Percolator

    SciTech Connect (OSTI)

    Granholm, Viktor; Kim, Sangtae; Navarro, Jose' C.; Sjolund, Erik; Smith, Richard D.; Kall, Lukas

    2014-02-28T23:59:59.000Z

    To identify peptides and proteins from the large number of fragmentation spectra in mass spectrometrybased proteomics, researches commonly employ so called database search engines. Additionally, postprocessors like Percolator have been used on the results from such search engines, to assess confidence, infer peptides and generally increase the number of identifications. A recent search engine, MS-GF+, has previously been showed to out-perform these classical search engines in terms of the number of identified spectra. However, MS-GF+ generates only limited statistical estimates of the results, hence hampering the biological interpretation. Here, we enabled Percolator-processing for MS-GF+ output, and observed an increased number of identified peptides for a wide variety of datasets. In addition, Percolator directly reports false discovery rate estimates, such as q values and posterior error probabilities, as well as p values, for peptide-spectrum matches, peptides and proteins, functions useful for the whole proteomics community.

  7. Energy absorption in Ni-Mn-Ga/ polymer composites

    E-Print Network [OSTI]

    Feuchtwanger, Jorge

    2006-01-01T23:59:59.000Z

    In recent years Ni-Mn-Ga has attracted considerable attention as a new kind of actuator material. Off-stoichiometric single crystals of Ni2MnGa can regularly exhibit 6% strain in tetragonal martensites and orthorhombic ...

  8. Degradation mechanisms of GaN high electron mobility transistors

    E-Print Network [OSTI]

    Joh, Jungwoo

    2007-01-01T23:59:59.000Z

    In spite of their extraordinary performance, GaN high electron mobility transistors (HEMT) have still limited reliability. In RF power applications, GaN HEMTs operate at high voltage where good reliability is essential. ...

  9. On strongly GA-convex functions and stochastic processes

    SciTech Connect (OSTI)

    Bekar, Nurgül Okur [Department of Statistics, Giresun University, Giresun (Turkey); Akdemir, Hande Günay; ??can, ?mdat [Department of Mathematics, Giresun University, Giresun (Turkey)

    2014-08-20T23:59:59.000Z

    In this study, we introduce strongly GA-convex functions and stochastic processes. We provide related well-known Kuhn type results and Hermite-Hadamard type inequality for strongly GA-convex functions and stochastic processes.

  10. TEM-Untersuchungen an GaN basierten Halbleiterheterostrukturen fur

    E-Print Network [OSTI]

    Schubart, Christoph

    TEM-Untersuchungen an GaN basierten Halbleiterheterostrukturen f¨ur optoelektronische Anwendungen . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 5.1.2 Versetzungen bei Homoapitaxie auf GaN-Substraten . . . . 79 5.2 Versetzungsreduktion durch

  11. GaN Nanopore Arrays: Fabrication and Characterization

    E-Print Network [OSTI]

    Wang, Yadong

    GaN nanopore arrays with pore diameters of approximately 75 nm were fabricated by inductively coupled plasma etching (ICP) using anodic aluminum oxide (AAO) films as etch masks. Nanoporous AAO films were formed on the GaN ...

  12. Height stabilization of GaSb/GaAs quantum dots by Al-rich capping

    SciTech Connect (OSTI)

    Smakman, E. P., E-mail: e.p.smakman@tue.nl; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, Den Dolech 2, 5612 AZ Eindhoven (Netherlands); DeJarld, M.; Martin, A. J.; Millunchick, J. [Department of Material Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Luengo-Kovac, M.; Sih, V. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

    2014-09-01T23:59:59.000Z

    GaSb quantum dots (QDs) in a GaAs matrix are investigated with cross-sectional scanning tunneling microscopy (X-STM) and photoluminescence (PL). We observe that Al-rich capping materials prevent destabilization of the nanostructures during the capping stage of the molecular beam epitaxy (MBE) growth process and thus preserves the QD height. However, the strain induced by the absence of destabilization causes many structural defects to appear around the preserved QDs. These defects originate from misfit dislocations near the GaSb/GaAs interface and extend into the capping layer as stacking faults. The lack of a red shift in the QD PL suggests that the preserved dots do not contribute to the emission spectra. We suggest that a better control over the emission wavelength and an increase of the PL intensity is attainable by growing smaller QDs with an Al-rich overgrowth.

  13. 2DEG electrodes for piezoelectric transduction of AlGaN/GaN MEMS resonators

    E-Print Network [OSTI]

    Weinstein, Dana

    A 2D electron gas (2DEG) interdigitated transducer (IDT) in Gallium Nitride (GaN) resonators is introduced and demonstrated. This metal-free transduction does not suffer from the loss mechanisms associated with more commonly ...

  14. High-field quasi-ballistic transport in AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Danilchenko, B. A.; Tripachko, N. A. [Institute of Physics, NASU, Pr. Nauki 46, Kiev 03028 (Ukraine); Belyaev, A. E. [Institute of Semiconductor Physics, NASU, Pr. Nauki 45, Kiev 03028 (Ukraine); Vitusevich, S. A., E-mail: s.vitusevich@fz-juelich.de; Hardtdegen, H.; Lüth, H. [Peter Grünberg Institute (PGI-8,PGI-9), Forschungszentrum Jülich, Jülich D-52425 (Germany)

    2014-02-17T23:59:59.000Z

    Mechanisms of electron transport formation in 2D conducting channels of AlGaN/GaN heterostructures in extremely high electric fields at 4.2?K have been studied. Devices with a narrow constriction for the current flow demonstrate high-speed electron transport with an electron velocity of 6.8?×?10{sup 7}?cm/s. Such a velocity is more than two times higher than values reported for conventional semiconductors and about 15% smaller than the limit value predicted for GaN. Superior velocity is attained in the channel with considerable carrier reduction. The effect is related to a carrier runaway phenomenon. The results are in good agreement with theoretical predictions for GaN-based materials.

  15. AlGaN/GaN High-Electron-Mobility Transistor Employing an Additional Gate for High-Voltage Switching Applications

    E-Print Network [OSTI]

    Seo, Kwang Seok

    AlGaN/GaN High-Electron-Mobility Transistor Employing an Additional Gate for High-Voltage Switching 16, 2004; accepted May 10, 2005; published September 8, 2005) We have proposed and fabricated an AlGaN/GaN: GaN, AlGaN, HEMT, switch 1. Introduction GaN has attracted attention for high-power and high

  16. Cubic AlGaN/GaN Hetero-Junction Field-Effect Transistors with Normally-on and Normally-off

    E-Print Network [OSTI]

    As, Donat Josef

    Cubic AlGaN/GaN Hetero-Junction Field-Effect Transistors with Normally-on and Normally-effect transistors (HFETs) in GaN technology. HFET structures were fabricated of non-polar cubic AlGaN/GaN hetero insulation of 3C-SiC was realized by Ar+ implantation before c-AlGaN/GaN growth. HFETs with normally

  17. A 3-10 GHZLCR-matched Power Amplifier using Flip-Chip Mounted AlGaN/GaN HEMTs

    E-Print Network [OSTI]

    York, Robert A.

    WE4A-5 A 3-10 GHZLCR-matched Power Amplifier using Flip-Chip Mounted AlGaN/GaN HEMTs Jane J a GaN-based broadband power amplifier using AlGaN/GaN-HEMTs, grown on sapphire substrates amplifier using GaN- HEMTs-on-Sapphire. I INTRODUCTION GaN HEMTs have enormous potential for realizing high

  18. IPAP Conference Series 1: IWN2000, Nov., 2000 1 Morphology Dependent Growth Kinetics of Ga-polar GaN(0001)

    E-Print Network [OSTI]

    Cohen, Philip I.

    IPAP Conference Series 1: IWN2000, Nov., 2000 1 Morphology Dependent Growth Kinetics of Ga-polar GaN, cohen@ece.umn.edu GaN grown on Ga polar GaN templates prepared by metal-organic vapor deposition shows to equilibrium models of the growth. The results indicate that Ga-polar GaN(0001) has a step energy of the order

  19. Engineering of AlGaN-Delta-GaN Quantum-Well Gain Media for Mid-and Deep-Ultraviolet Lasers

    E-Print Network [OSTI]

    Gilchrist, James F.

    Engineering of AlGaN-Delta-GaN Quantum-Well Gain Media for Mid- and Deep-Ultraviolet Lasers Volume.1109/JPHOT.2013.2248705 1943-0655/$31.00 Ó2013 IEEE #12;Engineering of AlGaN-Delta-GaN Quantum-Well Gain@Lehigh.Edu). Abstract: The gain characteristics of AlGaN-delta-GaN quantum wells (QWs) with varying delta-GaN positions

  20. This form is for use by MS students applying for a 2nd MS, Engineer or PhD degrees or for Engineer

    E-Print Network [OSTI]

    Prinz, Friedrich B.

    This form is for use by MS students applying for a 2nd MS, Engineer or PhD degrees or for Engineer degree students applying for PhD. The form should be completed and returned to the CEE department office degree goal: ( ) 2nd MS ( ) Engineer ( ) PhD Field of study

  1. Recent progress in InGaAsSb/GaSb TPV devices

    SciTech Connect (OSTI)

    Shellenbarger, Z.A.; Mauk, M.G.; DiNetta, L.C. [AstroPower, Inc., Newark, DE (United States); Charache, G.W. [Lockheed Martin Corp., Schenectady, NY (United States)

    1996-05-01T23:59:59.000Z

    AstroPower is developing InGaAsSb thermophotovoltaic (TPV) devices. This photovoltaic cell is a two-layer epitaxial InGaAsSb structure formed by liquid-phase epitaxy on a GaSb substrate. The (direct) bandgap of the In{sub 1{minus}x}Ga{sub x}As{sub 1{minus}y}Sb{sub y} alloy is 0.50 to 0.55 eV, depending on its exact alloy composition (x,y); and is closely lattice-matched to the GaSb substrate. The use of the quaternary alloy, as opposed to a ternary alloy--such as, for example InGaAs/InP--permits low bandgap devices optimized for 1,000 to 1,500 C thermal sources with, at the same time, near-exact lattice matching to the GaSb substrate. Lattice matching is important since even a small degree of lattice mismatch degrades device performance and reliability and increases processing complexity. Internal quantum efficiencies as high as 95% have been measured at a wavelength of 2 microns. At 1 micron wavelengths, internal quantum efficiencies of 55% have been observed. The open-circuit voltage at currents of 0.3 A/cm{sup 2} is 0.220 volts and 0.280 V for current densities of 2 A/cm{sup 2}. Fill factors of 56% have been measured at 60 mA/cm{sup 2}. However, as current density increases there is some decrease in fill factor. The results to date show that the GaSb-based quaternary compounds provide a viable and high performance energy conversion solution for thermophotovoltaic systems operating with 1,000 to 1,500 C source temperatures.

  2. AlGaAs/GaAs photovoltaic converters for high power narrowband radiation

    SciTech Connect (OSTI)

    Khvostikov, Vladimir; Kalyuzhnyy, Nikolay; Mintairov, Sergey; Potapovich, Nataliia; Shvarts, Maxim; Sorokina, Svetlana; Andreev, Viacheslav [Ioffe Physical-Technical Institute, 26 Polytechnicheskaya, St. Petersburg, 194021 (Russian Federation); Luque, Antonio [Ioffe Physical-Technical Institute, 26 Polytechnicheskaya, St. Petersburg, 194021, Russia and Instituto de Energia Solar, Universidad Politecnica de Madrid, Madrid (Spain)

    2014-09-26T23:59:59.000Z

    AlGaAs/GaAs-based laser power PV converters intended for operation with high-power (up to 100 W/cm{sup 2}) radiation were fabricated by LPE and MOCVD techniques. Monochromatic (? = 809 nm) conversion efficiency up to 60% was measured at cells with back surface field and low (x = 0.2) Al concentration 'window'. Modules with a voltage of 4 V and the efficiency of 56% were designed and fabricated.

  3. Sheet resistance under Ohmic contacts to AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Haj?asz, M., E-mail: m.hajlasz@m2i.nl [Materials innovation institute (M2i), Mekelweg 2, 2628 CD, Delft (Netherlands); MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands); Donkers, J. J. T. M.; Sque, S. J.; Heil, S. B. S. [NXP Semiconductors Research, High Tech Campus 46, 5656 AE, Eindhoven (Netherlands); Gravesteijn, D. J. [NXP Semiconductors Research, High Tech Campus 46, 5656 AE, Eindhoven (Netherlands); MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands); Rietveld, F. J. R. [NXP Semiconductors, Gerstweg 2, 6534 AE, Nijmegen (Netherlands); Schmitz, J. [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE, Enschede (Netherlands)

    2014-06-16T23:59:59.000Z

    For the determination of specific contact resistance in semiconductor devices, it is usually assumed that the sheet resistance under the contact is identical to that between the contacts. This generally does not hold for contacts to AlGaN/GaN structures, where an effective doping under the contact is thought to come from reactions between the contact metals and the AlGaN/GaN. As a consequence, conventional extraction of the specific contact resistance and transfer length leads to erroneous results. In this Letter, the sheet resistance under gold-free Ti/Al-based Ohmic contacts to AlGaN/GaN heterostructures on Si substrates has been investigated by means of electrical measurements, transmission electron microscopy, and technology computer-aided design simulations. It was found to be significantly lower than that outside of the contact area; temperature-dependent electrical characterization showed that it exhibits semiconductor-like behavior. The increase in conduction is attributed to n-type activity of nitrogen vacancies in the AlGaN. They are thought to form during rapid thermal annealing of the metal stack when Ti extracts nitrogen from the underlying semiconductor. The high n-type doping in the region between the metal and the 2-dimensional electron gas pulls the conduction band towards the Fermi level and enhances horizontal electron transport in the AlGaN. Using this improved understanding of the properties of the material underneath the contact, accurate values of transfer length and specific contact resistance have been extracted.

  4. TEM and HRXRD Analysis of LP MOVPE Grown InGaP/GaAs epilayers

    SciTech Connect (OSTI)

    Pelosi, Claudio; Bosi, Matteo; Attolini, Giovanni; Germini, Fabrizio; Frigeri, Cesare [CNR-IMEM Institute, Parco Area delle Scienze 37a, Loc Fontanini 43010 Parma (Italy); Prutskij, Tatiana [Instituto de Ciencias, BUAP, Privada 17 Norte, no. 3417, colSanMiguel Hueyotlipan, 72050 Puebla, Pue. (Mexico)

    2007-04-10T23:59:59.000Z

    The diffusion phenomena at interfaces between GaAs/InGaP layers grown by low pressure MOVPE have been studied by dark field (DF) transmission Electron Microscopy (TEM) and High resolution X-ray Diffractometry (HRXRD). By comparing the results of the two techniques a mismatched layer containing P or P and In has been evidenced. The causes of this behavior are briefly discussed.

  5. Guided Neuronal Growth on Arrays of Biofunctionalized GaAs/InGaAs Semiconductor Microtubes

    E-Print Network [OSTI]

    Cornelius S. Bausch; Aune Koitmäe; Eric Stava; Amanda Price; Pedro J. Resto; Yu Huang; David Sonnenberg; Yuliya Stark; Christian Heyn; Justin C. Williams; Erik W. Dent; Robert H. Blick

    2013-05-06T23:59:59.000Z

    We demonstrate embedded growth of cortical mouse neurons in dense arrays of semiconductor microtubes. The microtubes, fabricated from a strained GaAs/InGaAs heterostructure, guide axon growth through them and enable electrical and optical probing of propagating action potentials. The coaxial nature of the microtubes -- similar to myelin -- is expected to enhance the signal transduction along the axon. We present a technique of suppressing arsenic toxicity and prove the success of this technique by overgrowing neuronal mouse cells.

  6. InGaN/GaN quantum wells for polariton laser diodes: Role of inhomogeneous broadening

    SciTech Connect (OSTI)

    Glauser, Marlene; Mounir, Christian; Rossbach, Georg; Feltin, Eric; Carlin, Jean-François; Butté, Raphaël; Grandjean, Nicolas [École Polytechnique Fédérale de Lausanne (EPFL), Institute of Condensed Matter Physics, CH-1015 Lausanne (Switzerland)

    2014-06-21T23:59:59.000Z

    Contrary to the case of III-nitride based visible light-emitting diodes for which the inhomogeneous linewidth broadening characteristic of InGaN-based multiple quantum well (MQW) heterostructures does not appear as a detrimental parameter, such a broadening issue can prevent a microcavity (MC) system entering into the strong light-matter coupling regime (SCR). The impact of excitonic disorder in low indium content (x???0.1) In{sub x}Ga{sub 1–x}N/GaN MQW active regions is therefore investigated for the subsequent realization of polariton laser diodes by considering both simulations and optical characterizations. It allows deriving the requirements for such MQWs in terms of absorption, emission linewidth, and Stokes shift. Systematic absorption-like and photoluminescence (PL) spectroscopy experiments are performed on single and multiple In{sub 0.1}Ga{sub 0.9}N/GaN quantum wells (QWs). Micro-PL mappings reveal a low temperature PL linewidth of ?30?meV, compatible with SCR requirements, for single QWs for which the microscopic origin responsible for this broadening is qualitatively discussed. When stacking several InGaN/GaN QWs, a departure from such a narrow linewidth value and an increase in the Stokes shift are observed. Various possible reasons for this degradation such as inhomogeneous built-in field distribution among the QWs are then identified. An alternative solution for the MC design to achieve the SCR with the InGaN alloy is briefly discussed.

  7. Rapid Communications Strong piezoelectricity in individual GaN nanowires

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Rapid Communications Strong piezoelectricity in individual GaN nanowires Majid Minary@northwestern.edu (Received 12 July 2011; accepted 15 September 2011) Abstract GaN nanowires are promising building blocks piezoelectricity in individual single-crystal GaN nanowires revealed by direct measurement of the piezoelectric

  8. GaN Radiation Detectors for Particle Physics and

    E-Print Network [OSTI]

    Glasgow, University of

    GaN Radiation Detectors for Particle Physics and Synchrotron Applications James Paul Grant and monitoring applications. Gallium nitride (GaN) was investigated as a radiation hard particle detector diameter on three epitaxial GaN wafers grown on a sapphire sub- strate. Two of the wafers were obtained

  9. New Faces of GaN: Growth, Doping and Devices

    E-Print Network [OSTI]

    California at Santa Barbara, University of

    New Faces of GaN: Growth, Doping and Devices James S. Speck Materials Department University of California Santa Barbara, CA LEO of a-GaN from circular opening Engineering Insights 2006 #12;#12;Personnel. Wraback (ARL) $$$ JST ­ ERATO UCSB SSLDC AFOSR ONR #12;Reversed direction of polarization Bulk GaN

  10. Analysis of the AlGaN/GaN vertical bulk current on Si, sapphire, and free-standing GaN substrates

    SciTech Connect (OSTI)

    Perez-Tomas, A.; Fontsere, A.; Llobet, J. [IMB-CNM-CSIC, Campus UAB, 08193 Bellaterra, Barcelona, CAT (Spain); Placidi, M. [IREC, Jardins Dones de Negre 1, 08930 Sant Adria de Besos, Barcelona (Spain); Rennesson, S.; Chenot, S.; Moreno, J. C.; Cordier, Y. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Baron, N. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); PICOGIGA International, Pl M. Rebuffat, Courtaboeuf 7, 91140 Villejust (France)

    2013-05-07T23:59:59.000Z

    The vertical bulk (drain-bulk) current (I{sub db}) properties of analogous AlGaN/GaN hetero-structures molecular beam epitaxially grown on silicon, sapphire, and free-standing GaN (FS-GaN) have been evaluated in this paper. The experimental I{sub db} (25-300 Degree-Sign C) have been well reproduced with physical models based on a combination of Poole-Frenkel (trap assisted) and hopping (resistive) conduction mechanisms. The thermal activation energies (E{sub a}), the (soft or destructive) vertical breakdown voltage (V{sub B}), and the effect of inverting the drain-bulk polarity have also been comparatively investigated. GaN-on-FS-GaN appears to adhere to the resistive mechanism (E{sub a} = 0.35 eV at T = 25-300 Degree-Sign C; V{sub B} = 840 V), GaN-on-sapphire follows the trap assisted mechanism (E{sub a} = 2.5 eV at T > 265 Degree-Sign C; V{sub B} > 1100 V), and the GaN-on-Si is well reproduced with a combination of the two mechanisms (E{sub a} = 0.35 eV at T > 150 Degree-Sign C; V{sub B} = 420 V). Finally, the relationship between the vertical bulk current and the lateral AlGaN/GaN transistor leakage current is explored.

  11. (WPI-iCeMS) Pure Nano Drugs*

    E-Print Network [OSTI]

    Takada, Shoji

    (WPI-iCeMS) SN-38 50 nm * Pure Nano Drugs* SN-38 10 HepG2* JST (-STEP Permeation and Retention (EPR)* EPR 20100 nm SN-38 SN-38 * SN-38 * SN-38 20 SN-38 Pure Nano Drugs

  12. SPE-163690-MS Synthetic, Geomechanical Logs for Marcellus Shale

    E-Print Network [OSTI]

    Mohaghegh, Shahab

    SPE-163690-MS Synthetic, Geomechanical Logs for Marcellus Shale M. O. Eshkalak, SPE, S. D of production from shale gas reservoirs. In this study, synthetic geomechanical logs (Including following-driven models are developed that are capable of generating synthetic geomechanical logs from conventional logs

  13. Deborah K. Smith Department of Geology and Geophysics, MS 22

    E-Print Network [OSTI]

    Smith, Deborah K.

    Deborah K. Smith Department of Geology and Geophysics, MS 22 Woods Hole Oceanographic Institution: Jordan, T. H., H. W. Menard, and D.K. Smith, Density and size distribution of seamounts in the eastern. Smith, H. W. Menard, J. A. Orcutt and T. H. Jordan, Seismic reflection site survey: correlation

  14. PhD Chemical Engineering MS Chemical Engineering

    E-Print Network [OSTI]

    Collins, Gary S.

    phenomena in nature and technology. The chemical engineer leverages knowledge of molecular processes across1 PhD Chemical Engineering MS Chemical Engineering Bylaws Gene and Linda Voiland School of Chemical Engineering and Bioengineering College of Engineering and Architecture Approved by Voiland School faculty

  15. The Next Generation Isotope Ratio MS DELTA V Advantage

    E-Print Network [OSTI]

    Lachniet, Matthew S.

    on front panel - All pumps inside - Low noise design #12;T The Next Generation Isotope Ratio MS More than with intrinsic alignment of all ion optical components - Integrated signal amplifiers and digitizers - All ion - Comprehensive set of automated diagnostics · Compact and user-friendly design - Small footprint - Space for on

  16. MS in Water, Society, and Policy University of Arizona

    E-Print Network [OSTI]

    Fay, Noah

    MS in Water, Society, and Policy University of Arizona Biological Sciences East, Room 325 Phone of scholarship. The Water, Society and Policy Program draws on the expertise of scientists, social scientists and the Environment School of Geography and Development Water Resources Research Center Institute

  17. Ms. Vicki Cowart Secretary of the Board of Trustees

    E-Print Network [OSTI]

    Executive Officer of Planned Parenthood of the Rocky Mountains. Previously she served for ten years as the State Geologist and Director of the State of Colorado Geological Survey. Early in her career she worked as a geophysicist for several oil and gas companies and was a District Manager for Schlumberger Well Services. Ms

  18. GRADUATE HANDBOOK M.S. and PhD Programs

    E-Print Network [OSTI]

    GRADUATE HANDBOOK M.S. and PhD Programs in Mechanical Engineering and Engineering Mechanics another MSU program 8 2.3 Admission Requirements: Ph.D. Programs.................................................. 9 2.3.1 Regular Status. 9 2.3.2 Accelerated Ph.D. Program Entry 9 2.3.3 Provisional Status. 10 2

  19. A New Combustion Synthesis Method for GaN:Eu3+ and Ga2O3 :Eu3+

    E-Print Network [OSTI]

    McKittrick, Joanna

    A New Combustion Synthesis Method for GaN:Eu3+ and Ga2O3 :Eu3+ Luminescent Powders G. A. Hirata1 between the precursors. The preparation of Eu-doped Ga2O3 powders was achieved using a new combustion)3 and Ga(NO3)3 as the precursors and hydrazine as (non-carbonaceous) fuel. A spontaneous combustion

  20. Electron mobility enhancement in AlN/GaN/AlN heterostructures with InGaN nanogrooves

    E-Print Network [OSTI]

    improve the room-temperature carrier mobility in wurtzite AlN/GaN/AlN heterostructures, which is limited consider a narrow groove made of InxGa1-xN with small In content x inside a wurtzite AlN/GaN/AlN heteroN 2 nm /GaN 3 nm /AlN 3 nm . A well-known feature of wurtzite heterostructures is a strong buit

  1. Growth of GaN on porous SiC and GaN substrates C. K. Inoki1

    E-Print Network [OSTI]

    Feenstra, Randall

    1 Growth of GaN on porous SiC and GaN substrates C. K. Inoki1 , T. S. Kuan1 , Ashutosh Sagar2 , C, Albuquerque, NM 87185 4 Beckman Institute, University of Illinois, Urbana, IL 61801 GaN films were grown on porous SiC and GaN templates using both plasma-assisted molecular beam epitaxy (PAMBE) and metal

  2. Structural, morphological, and optical properties of AlGaN/GaN heterostructures with AlN buffer and interlayer

    E-Print Network [OSTI]

    Ozbay, Ekmel

    N buffer layer BL grown on an Al2O3 substrate and an AlN IL grown under the AlGaN ternary layer TL. In the present study, we investigate the effects of an AlN BL on an Al2O3 substrate and an AlN IL between an AlGaNStructural, morphological, and optical properties of AlGaN/GaN heterostructures with AlN buffer

  3. Real-time reflectance-difference spectroscopy of GaAs molecular beam epitaxy homoepitaxial growth

    SciTech Connect (OSTI)

    Lastras-Martínez, A., E-mail: alm@cactus.iico.uaslp.mx, E-mail: alastras@gmail.com; Ortega-Gallegos, J.; Guevara-Macías, L. E.; Nuñez-Olvera, O.; Balderas-Navarro, R. E.; Lastras-Martínez, L. F. [Instituto de Investigación en Comunicación Optica, Universidad Autónoma de San Luis Potosí, Alvaro Obregón 64, San Luis Potosí, SLP 78000 (Mexico); Lastras-Montaño, L. A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Lastras-Montaño, M. A. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, Santa Barbara, California 93106 (United States)

    2014-03-01T23:59:59.000Z

    We report on real time-resolved Reflectance-difference (RD) spectroscopy of GaAs(001) grown by molecular beam epitaxy, with a time-resolution of 500 ms per spectrum within the 2.3–4.0 eV photon energy range. Through the analysis of transient RD spectra we demonstrated that RD line shapes are comprised of two components with different physical origins and determined their evolution during growth. Such components were ascribed to the subsurface strain induced by surface reconstruction and to surface stoichiometry. Results reported in this paper render RD spectroscopy as a powerful tool for the study of fundamental processes during the epitaxial growth of zincblende semiconductors.

  4. From Schottky to Ohmic graphene contacts to AlGaN/GaN heterostructures: Role of the AlGaN layer microstructure

    SciTech Connect (OSTI)

    Fisichella, G. [CNR-IMM, Strada VIII, 5, 95121 Catania (Italy); Department of Electronic Engineering, University of Catania, 95124 Catania (Italy); Greco, G.; Roccaforte, F.; Giannazzo, F. [CNR-IMM, Strada VIII, 5, 95121 Catania (Italy)

    2014-08-11T23:59:59.000Z

    The electrical behaviour of graphene (Gr) contacts to Al{sub x}Ga{sub 1?x}N/GaN heterostructures has been investigated, focusing, in particular, on the impact of the AlGaN microstructure on the current transport at Gr/AlGaN interface. Two Al{sub 0.25}Ga{sub 0.75}N/GaN heterostructures with very different quality in terms of surface roughness and defectivity, as evaluated by atomic force microscopy (AFM) and transmission electron microscopy, were compared in this study, i.e., a uniform and defect-free sample and a sample with a high density of typical V-defects, which locally cause a reduction of the AlGaN thickness. Nanoscale resolution current voltage (I-V) measurements by an Au coated conductive AFM tip were carried out at several positions both on the bare and Gr-coated AlGaN surfaces. Rectifying contacts were found onto both bare AlGaN surfaces, but with a more inhomogeneous and lower Schottky barrier height (?{sub B}???0.6?eV) for AlGaN with V-defects, with respect to the case of the uniform AlGaN (?{sub B}???0.9?eV). Instead, very different electrical behaviours were observed in the presence of the Gr interlayer between the Au tip and AlGaN, i.e., a Schottky contact with reduced barrier height (?{sub B} ? 0.4?eV) for the uniform AlGaN and an Ohmic contact for the AlGaN with V-defects. Interestingly, excellent lateral uniformity of the local I-V characteristics was found in both cases and can be ascribed to an averaging effect of the Gr electrode over the AlGaN interfacial inhomogeneities. Due to the locally reduced AlGaN layer thickness, V defect act as preferential current paths from Gr to the 2DEG and can account for the peculiar Ohmic behaviour of Gr contacts on defective AlGaN.

  5. Lattice-Mismatched GaAs/InGaAs Two-Junction Solar Cells by Direct Wafer Bonding

    SciTech Connect (OSTI)

    Tanabe, K.; Aiken, D. J.; Wanlass, M. W.; Morral, A. F.; Atwater, H. A.

    2006-01-01T23:59:59.000Z

    Direct bonded interconnect between subcells of a lattice-mismatched III-V compound multijunction cell would enable dislocation-free active regions by confining the defect network needed for lattice mismatch accommodation to tunnel junction interfaces, while metamorphic growth inevitably results in less design flexibility and lower material quality than is desirable. The first direct-bond interconnected multijunction solar cell, a two-terminal monolithic GaAs/InGaAs two-junction solar cell, is reported and demonstrates viability of direct wafer bonding for solar cell applications. The tandem cell open-circuit voltage was approximately the sum of the subcell open-circuit voltages. This achievement shows direct bonding enables us to construct lattice-mismatched III-V multijunction solar cells and is extensible to an ultrahigh efficiency InGaP/GaAs/InGaAsP/InGaAs four-junction cell by bonding a GaAs-based lattice-matched InGaP/GaAs subcell and an InP-based lattice-matched InGaAsP/InGaAs subcell. The interfacial resistance experimentally obtained for bonded GaAs/InP smaller than 0.10 Ohm-cm{sup 2} would result in a negligible decrease in overall cell efficiency of {approx}0.02%, under 1-sun illumination.

  6. X-ray diffraction analysis of InGaP/GaAs heterointerfaces grown by metalorganic chemical vapor deposition

    SciTech Connect (OSTI)

    Nittono, T.; Hyuga, F. [NTT System Electronics Laboratories 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa, 243-01 (Japan)] [NTT System Electronics Laboratories 3-1, Morinosato Wakamiya, Atsugi-shi, Kanagawa, 243-01 (Japan)

    1997-03-01T23:59:59.000Z

    InGaP/GaAs heterointerfaces grown by metalorganic chemical vapor deposition have been characterized by a high-resolution x-ray diffraction analysis of multiple quantum well structures. The flow of AsH{sub 3} to InGaP surface produces an InGaAs-like interfacial layer at the GaAs-on-InGaP interface, indicating P atoms of the InGaP surface are easily replaced by As atoms. The flow of PH{sub 3} to GaAs surface, on the other hand, does not make any detectable interfacial layer, indicating that almost no As atoms of the GaAs surface are replaced by P atoms. It is also found that the flow of trimethylgallium (TMG) to the InGaP surface produces a GaP-like interfacial layer. This interfacial layer is probably formed by the reaction between TMG and excessive P atoms on the InGaP surface or residual PH{sub 3} in the growth chamber. {copyright} {ital 1997 American Institute of Physics.}

  7. Physica B 376377 (2006) 486490 Preferential substitution of Fe on physically equivalent Ga sites in GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    2006-01-01T23:59:59.000Z

    in GaN W. GehlhoffÃ, D. Azamat1 , U. Haboeck, A. Hoffmann Institute for Solid State Physics, Technical freestanding hydride vapor phase grown GaN have been studied in the X- and Q-band. A complex resonance pattern with C3v symmetry in the wurtzite structure of GaN. Aside from the displacement of their magnetic axis

  8. Superluminescence in Green Emission GaInN/GaN Quantum Well Structures under Pulsed Laser Excitation

    E-Print Network [OSTI]

    Wetzel, Christian M.

    and bulk GaN substrates, respectively. Under intense pulsed photo excitation, we observed strong the same excitation conditions, the blue shift for the m-axis grown structure on bulk GaN substrate is less-plane sapphire substrate and along the non-polar m-axis on m-plane bulk GaN substrate. The frequently used

  9. Composition and Interface Analysis of InGaN/GaN Multiquantum-Wells on GaN Substrates Using Atom Probe Tomography

    SciTech Connect (OSTI)

    Liu, Fang; Huang, Li; Davis, Robert F.; Porter, Lisa M.; Schreiber, Daniel K.; Kuchibhatla, S. V. N. T.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Preble, Edward; Paskova, Tanya; Evans, K. R.

    2014-09-04T23:59:59.000Z

    In0.20Ga0.80N/GaN multi-quantum wells grown on [0001]-oriented GaN substrates with and without an InGaN buffer layer were characterized using three-dimensional atom probe tomography. In all samples, the upper interfaces of the QWs were slightly more diffuse than the lower interfaces. The buffer layers did not affect the roughness of the interfaces within the quantum well structure, a result attributed to planarization of the surface of the 1st GaN barrier layer which had an average root-mean-square roughness of 0.177 nm. The In and Ga distributions within the MQWs followed the expected distributions for a random alloy with no indications of In clustering.

  10. Point defect balance in epitaxial GaSb

    SciTech Connect (OSTI)

    Segercrantz, N., E-mail: natalie.segercrantz@aalto.fi; Slotte, J.; Makkonen, I.; Kujala, J.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 14100, FIN-00076 Aalto Espoo (Finland); Song, Y.; Wang, S. [Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Göteborg (Sweden); State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences 865 Changning Road, Shanghai 200050 (China)

    2014-08-25T23:59:59.000Z

    Positron annihilation spectroscopy in both conventional and coincidence Doppler broadening mode is used for studying the effect of growth conditions on the point defect balance in GaSb:Bi epitaxial layers grown by molecular beam epitaxy. Positron annihilation characteristics in GaSb are also calculated using density functional theory and compared to experimental results. We conclude that while the main positron trapping defect in bulk samples is the Ga antisite, the Ga vacancy is the most prominent trap in the samples grown by molecular beam epitaxy. The results suggest that the p–type conductivity is caused by different defects in GaSb grown with different methods.

  11. Room-temperature cw operation of InGaAsP/InGaP lasers at 727 nm grown on GaAs substrates by liquid phase epitaxy

    SciTech Connect (OSTI)

    Wakao, K.; Nishi, H.; Kusunoki, T.; Isozumi, S.; Ohsaka, S.

    1984-06-01T23:59:59.000Z

    InGaAsP/InGaP lasers emitting at 724--727 nm have been fabricated on GaAs substrates using liquid phase epitaxy. The threshold current is reduced to 8 kA/cm/sup 2/ by thinning the active layer. Room-temperature cw operation is achieved for the first time in the lasing wavelength range below 760 nm in this quaternary system.

  12. Self-assembled In0.5Ga0.5As quantum dots on GaP Yuncheng Song,a

    E-Print Network [OSTI]

    Haller, Gary L.

    SAQDs . Several groups have investigated the growth of both InP and In-rich InGaP SAQDs on GaP.7­12 Most temperature operation of vis- ible light emitting diodes LEDs using InP/GaP and InGaP/ GaP SAQDs, respectively

  13. Current crowding in GaInN / GaN LEDs grown on insulating substrates X. Guo, E. F. Schubert and J. Jahns

    E-Print Network [OSTI]

    Jahns, Jürgen

    Current crowding in GaInN / GaN LEDs grown on insulating substrates X. Guo, E. F. Schubert and J spreading in a mesa-structure GaN-based LED grown on an insulating or semi-insulating substrate. (b. Jahns Current crowding in mesa-structure GaInN/GaN light-emitting diodes (LEDs) grown on insulating

  14. Gas-source molecular beam epitaxial growth and characterization of the (Al,In,Ga)NP/GaP material system and Its applications to light-emitting diodes

    E-Print Network [OSTI]

    Odnoblyudov, Vladimir

    2006-01-01T23:59:59.000Z

    ? G, Kcal/mol GaP GaN AlN o Substrate temperature, C Figurenm-thick GaN 0.006 P 0.994 layer on substrate temperature.substrate temperature for Reactions formation of AlP, GaP, GaN and

  15. IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 51, NO. 2, FEBRUARY 2003 653 AlGaN/GaN HFET Power Amplifier Integrated With

    E-Print Network [OSTI]

    Itoh, Tatsuo

    the first demonstration of a GaN-based HFET was done on a sapphire substrate in 1993 [1]­[3]. This is due crystal quality compared to that of the sapphire substrate. Thanks to steadfast progress in AlGaN/GaN HFETIEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 51, NO. 2, FEBRUARY 2003 653 AlGaN/GaN

  16. Tunable THz plasmon resonances in InGaAs/InP HEMT R. E. Peale*a

    E-Print Network [OSTI]

    Peale, Robert E.

    , high ns, and small m*. A variety of materials systems such as GaAs/AlGaAs [3], InGaP/InGaAs/GaAs [4

  17. Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1-xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    fabricated on freestanding GaN substrates T. Koyama and T.on freestanding m-plane GaN substrates. Although the ? inton the freestanding GaN substrate. cause the current was

  18. Reactive codoping of GaAlInP compound semiconductors

    DOE Patents [OSTI]

    Hanna, Mark Cooper (Boulder, CO); Reedy, Robert (Golden, CO)

    2008-02-12T23:59:59.000Z

    A GaAlInP compound semiconductor and a method of producing a GaAlInP compound semiconductor are provided. The apparatus and method comprises a GaAs crystal substrate in a metal organic vapor deposition reactor. Al, Ga, In vapors are prepared by thermally decomposing organometallic compounds. P vapors are prepared by thermally decomposing phospine gas, group II vapors are prepared by thermally decomposing an organometallic group IIA or IIB compound. Group VIB vapors are prepared by thermally decomposing a gaseous compound of group VIB. The Al, Ga, In, P, group II, and group VIB vapors grow a GaAlInP crystal doped with group IIA or IIB and group VIB elements on the substrate wherein the group IIA or IIB and a group VIB vapors produced a codoped GaAlInP compound semiconductor with a group IIA or IIB element serving as a p-type dopant having low group II atomic diffusion.

  19. Influence of Ga content on the structure and anomalous Hall effect of Fe{sub 1?x}Ga{sub x} thin films on GaSb(100)

    SciTech Connect (OSTI)

    Anh Tuan, Duong; Shin, Yooleemi; Viet Cuong, Tran; Cho, Sunglae, E-mail: slcho@ulsan.ac.kr [Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, Ulsan 680-749 (Korea, Republic of); Phan, The-Long [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

    2014-05-07T23:59:59.000Z

    The Fe{sub 1?x}Ga{sub x} thin films (x?=?0.4, 0.5) have been grown on GaSb(100) substrate using molecular beam epitaxy. An epitaxial film with bcc ?-Fe crystal structure (A2) is observed in Fe{sub 0.6}Ga{sub 0.4} film, while an impure Fe{sub 3}Ga phase with DO{sub 3} structure is appeared in Fe{sub 0.5}Ga{sub 0.5} film. The saturated magnetizations at room temperature are observed to be 570?emu/cm{sup 3} and 180?emu/cm{sup 3} and the coercivities to be 170 and 364?Oe for Fe{sub 0.6}Ga{sub 0.4} and Fe{sub 0.5}Ga{sub 0.5}, respectively. A hysteresis trend in Hall resistance vs. magnetic field is observed for Fe{sub 0.5}Ga{sub 0.5} film. However, there is a weak hysteresis noticed in Fe{sub 0.4}Ga{sub 0.6} thin film.

  20. Catastrophic degradation of InGaAsP/InGaP double-heterostructure lasers grown on (001) GaAs substrates by liquid-phase epitaxy

    SciTech Connect (OSTI)

    Ueda, O.; Wakao, K.; Komiya, S.; Yamaguchi, A.; Isozumi, S.; Umebu, I.

    1985-12-01T23:59:59.000Z

    Catastrophically degraded InGaAsP/InGaP double-heterostructure lasers grown on (001) GaAs substrates by liquid-phase epitaxy, emitting at 727 and 810 nm are investigated by photoluminescence topography, scanning electron microscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. The degradation is mainly due to catastrophic optical damage at the facet, i.e., development of <110> dark-line defects from the facet, and rarely due to catastrophic optical damage at some defects, i.e., development of <110> dark-line defects from the defects inside the stripe region. These <110> dark-line defects correspond to complicated dislocation networks connected with dark knots, and are quite similar to those observed in catastrophically degraded GaAlAs/GaAs double-heterostructure lasers. The degradation characteristics of the InGaAsP/InGaP double-heterostructure lasers are rather similar to those in GaAlAs/GaAs double-heterostructure lasers concerning the catastrophic degradation.

  1. Dynamics of thermalization in GaInN/GaN quantum wells grown on ammonothermal GaN

    SciTech Connect (OSTI)

    Binder, J.; Korona, K. P.; Wysmo?ek, A.; Kami?ska, M. [Faculty of Physics, University of Warsaw, ul. Hoza 69, 00-681 Warsaw (Poland); Köhler, K.; Kirste, L.; Ambacher, O. [Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg (Germany); Zaj?c, M.; Dwili?ski, R. [AMMONO SA, Czerwonego Krzy?a 2/31, 00-377 Warsaw (Poland)

    2013-12-14T23:59:59.000Z

    In this work, we present measurements of the dynamics of photoexcited carriers in GaInN/GaN quantum wells (QWs) grown on ammonothermal GaN, especially thermalization and recombination rates. Emission properties were measured by time-resolved photoluminescence (PL) and electroluminescence spectroscopy. Due to the use of high quality homoepitaxial material, we were able to obtain very valuable data on carrier thermalization. The temperature dependence of the QW energy observed in PL shows characteristic S-shape with a step of about 10?meV. Such a behavior (related to thermalization and localization at potential fluctuations) is often reported for QWs; but in our samples, the effect is smaller than in heteroepitaxial InGaN/GaN QWs due to lower potential fluctuation in our material. Absorption properties were studied by photocurrent spectroscopy measurements. A comparison of emission and absorption spectra revealed a shift in energy of about 60?meV. Contrary to PL, the QW energy observed in absorption decreases monotonically with temperature, which can be described by a Bose-like dependence E(T)?=?E(0) ? ?/(exp(?/T) ? 1), with parameters ??=?(0.11?±?0.01) eV, ??=?(355?±?20)?K, or by a Varshni dependence with coefficients ??=?(10?±?3) × 10{sup ?4}?eV/K and ??=?(1500?±?500) K. Taking into account absorption and emission, the fluctuation amplitude (according to Eliseev theory) was ??=?14?meV. The time resolved PL revealed that in a short period (<1?ns) after excitation, the PL peaks were broadened because of the thermal distribution of carriers. We interpreted this distribution in terms of quasi-temperature (T{sub q}) of the carriers. The initial T{sub q} was of the order of 500?K. The thermalization led to a fast decrease of T{sub q}. The obtained cooling time in the QW was ?{sub C}?=?0.3?ns, which was faster than the observed recombination time ?{sub R}?=?2.2?ns (at 4?K)

  2. Manipulation of emission energy in GaAs/AlGaAs core-shell nanowires with radial heterostructure

    SciTech Connect (OSTI)

    Barbosa, B. G.; Arakaki, H.; Souza, C. A. de; Pusep, Yu. A. [Instituto de Fisica de São Carlos, Universidade de São Paulo, 13560-970 Sao Carlos, SP (Brazil)

    2014-03-21T23:59:59.000Z

    Photoluminescence was studied in GaAs/AlGaAs nanowires (NWs) with different radial heterostructures. We demonstrated that manipulation of the emission energy may be achieved by appropriate choice of the shell structure. The emission at highest energy is generated in the NWs with tunneling thin AlGaAs inner shell and thin GaAs outer shell due to recombination of the photoexcited electrons confined in the outer shell with the holes in the core. Lower energy emission was shown to occur in the NWs with thick outer shell grown in the form of a short-period GaAs/AlGaAs multiple quantum well structure. In this case, the tunneling probability through the multiple quantum wells controls the energy emitted by the NWs. The doping of core results in dominated low energy emission from the GaAs core.

  3. 0.7-eV GaInAs Junction for a GaInP/GaAs/GaInAs(1eV)/GaInAs(0.7eV) Four-Junction Solar Cell

    SciTech Connect (OSTI)

    Friedman, D. J.; Geisz, J. F.; Norman, A. G.; Wanlass, M. W.; Kurtz, S. R.

    2006-01-01T23:59:59.000Z

    We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga{sub 0.5}In{sub 0.5} P/GaAs/Ga{sub 0.75}In{sub 0.25}As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga{sub 0.75}In{sub 0.25}As third junction is the last one grown, has demonstrated 38% efficiency, and 40% is likely in the near future. To achieve still further gains, a lower-bandgap Ga{sub x}In{sub 1-x}As fourth junction could be added to the three-junction structure for a four-junction cell whose efficiency could exceed 45% under concentration. Here, we present the initial development of the Ga{sub x}In{sub 1-x}As fourth junction. Junctions of various bandgaps ranging from 0.88 to 0.73 eV were grown, in order to study the effect of the different amounts of lattice mismatch. At a bandgap of 0.88 eV, junctions were obtained with very encouraging {approx}80% quantum efficiency, 57% fill factor, and 0.36 eV open-circuit voltage. The device performance degrades with decreasing bandgap (i.e., increasing lattice mismatch). We model the four-junction device efficiency vs. fourth junction bandgap to show that an 0.7-eV fourth-junction bandgap, while optimal if it could be achieved in practice, is not necessary; an 0.9-eV bandgap would still permit significant gains in multijunction cell efficiency while being easier to achieve than the lower-bandgap junction.

  4. MS211 -CALCULO NUMERICO -2o semestre de 2011

    E-Print Network [OSTI]

    Sussner, Peter

    MS211 - C´ALCULO NUM´ERICO - 2o semestre de 2011 turma professor sala e-mail A ´Alvaro R. De Pierro. An´alise Num´erica. Pioneira Thompson Learning, 2003. 2. M.C.Cunha. M´etodos Num´ericos. 2a edi¸c~ao, Editora da Unicamp, 2000. 3. M.A.Gomes Ruggiero, V. L. da Rocha Lopes. C´alculo Num´erico - Aspectos Te

  5. MS211 -CALCULO NUMERICO -2o semestre de 2014

    E-Print Network [OSTI]

    Sussner, Peter

    MS211 - C´ALCULO NUM´ERICO - 2o semestre de 2014 Turma Professor Sala­IMECC e-mail A M. Aparecida. Darezzo. C´alculo Num´erico - Aprendizagem com Apoio de Software. Thompson Learning, 2008. 2. R.L.Burden, J.D. Faires. An´alise Num´erica. Pioneira Thompson Learning, 2003. 3. M.C.Cunha. M´etodos Num´ericos

  6. Method for factor analysis of GC/MS data

    DOE Patents [OSTI]

    Van Benthem, Mark H; Kotula, Paul G; Keenan, Michael R

    2012-09-11T23:59:59.000Z

    The method of the present invention provides a fast, robust, and automated multivariate statistical analysis of gas chromatography/mass spectroscopy (GC/MS) data sets. The method can involve systematic elimination of undesired, saturated peak masses to yield data that follow a linear, additive model. The cleaned data can then be subjected to a combination of PCA and orthogonal factor rotation followed by refinement with MCR-ALS to yield highly interpretable results.

  7. Ga adsorbate on (0001) GaN: In situ characterization with quadrupole mass spectrometry and reflection high-energy electron diffraction

    E-Print Network [OSTI]

    Brown, J S; Koblmuller, G; Wu, F; Averbeck, R; Riechert, H; Speck, J S

    2006-01-01T23:59:59.000Z

    PA-MBE GaN growth conditions, with substrate temperatures ofthe GaN surface roughness evolution, substrate vicinality,vapor and substrate temperature could form the basis for GaN

  8. Two-locus linkage analysis in multiple sclerosis (MS)

    SciTech Connect (OSTI)

    Tienari, P.J. (National Public Health Institute, Helsinki (Finland) Univ. of Helsinki (Finland)); Terwilliger, J.D.; Ott, J. (Columbia Univ., New York (United States)); Palo, J. (Univ. of Helsinki (Finland)); Peltonen, L. (National Public Health Institute, Helsinki (Finland))

    1994-01-15T23:59:59.000Z

    One of the major challenges in genetic linkage analyses is the study of complex diseases. The authors demonstrate here the use of two-locus linkage analysis in multiple sclerosis (MS), a multifactorial disease with a complex mode of inheritance. In a set of Finnish multiplex families, they have previously found evidence for linkage between MS susceptibility and two independent loci, the myelin basic protein gene (MBP) on chromosome 18 and the HLA complex on chromosome 6. This set of families provides a unique opportunity to perform linkage analysis conditional on two loci contributing to the disease. In the two-trait-locus/two-marker-locus analysis, the presence of another disease locus is parametrized and the analysis more appropriately treats information from the unaffected family member than single-disease-locus analysis. As exemplified here in MS, the two-locus analysis can be a powerful method for investigating susceptibility loci in complex traits, best suited for analysis of specific candidate genes, or for situations in which preliminary evidence for linkage already exists or is suggested. 41 refs., 6 tabs.

  9. Refractive index of erbium doped GaN thin films

    SciTech Connect (OSTI)

    Alajlouni, S.; Sun, Z. Y.; Li, J.; Lin, J. Y.; Jiang, H. X., E-mail: hx.jiang@ttu.edu [Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, Texas 79409 (United States); Zavada, J. M. [Department of Electrical and Computer Engineering, Polytechnic Institute of New York University, Brooklyn, New York 11201 (United States)

    2014-08-25T23:59:59.000Z

    GaN is an excellent host for erbium (Er) to provide optical emission in the technologically important as well as eye-safe 1540?nm wavelength window. Er doped GaN (GaN:Er) epilayers were synthesized on c-plane sapphire substrates using metal organic chemical vapor deposition. By employing a pulsed growth scheme, the crystalline quality of GaN:Er epilayers was significantly improved over those obtained by conventional growth method of continuous flow of reaction precursors. X-ray diffraction rocking curve linewidths of less than 300?arc sec were achieved for the GaN (0002) diffraction peak, which is comparable to the typical results of undoped high quality GaN epilayers and represents a major improvement over previously reported results for GaN:Er. Spectroscopic ellipsometry was used to determine the refractive index of the GaN:Er epilayers in the 1540?nm wavelength window and a linear dependence on Er concentration was found. The observed refractive index increase with Er incorporation and the improved crystalline quality of the GaN:Er epilayers indicate that low loss GaN:Er optical waveguiding structures are feasible.

  10. Effect of Temperature on GaGdO/GaN Metal Oxide Semiconductor Field Effect Transistors

    SciTech Connect (OSTI)

    Abernathy, C.R.; Baca, A.; Chu, S.N.G.; Hong, M.; Lothian, J.R.; Marcus, M.A.; Pearton, S.J.; Ren, F.; Schurman, M.J.

    1998-10-14T23:59:59.000Z

    GaGdO was deposited on GaN for use as a gate dielectric in order to fabricate a depletion metal oxide semiconductor field effect transistor (MOSFET). This is the fmt demonstration of such a device in the III-Nitride system. Analysis of the effect of temperature on the device shows that gate leakage is significantly reduced at elevated temperature relative to a conventional metal semiconductor field effeet transistor (MESFET) fabricated on the same GaN layer. MOSFET device operation in fact improved upon heating to 400 C. Modeling of the effeet of temperature on contact resistance suggests that the improvement is due to a reduction in the parasitic resistances present in the device.

  11. Graphene in ohmic contact for both n-GaN and p-GaN

    SciTech Connect (OSTI)

    Zhong, Haijian; Liu, Zhenghui; Shi, Lin; Xu, Gengzhao; Fan, Yingmin; Huang, Zengli [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Wang, Jianfeng; Ren, Guoqiang; Xu, Ke, E-mail: kxu2006@sinano.ac.cn [Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Suzhou Nanowin Science and Technology Co., Ltd., Suzhou 215123 (China)

    2014-05-26T23:59:59.000Z

    The wrinkles of single layer graphene contacted with either n-GaN or p-GaN were found both forming ohmic contacts investigated by conductive atomic force microscopy. The local I–V results show that some of the graphene wrinkles act as high-conductive channels and exhibiting ohmic behaviors compared with the flat regions with Schottky characteristics. We have studied the effects of the graphene wrinkles using density-functional-theory calculations. It is found that the standing and folded wrinkles with zigzag or armchair directions have a tendency to decrease or increase the local work function, respectively, pushing the local Fermi level towards n- or p-type GaN and thus improving the transport properties. These results can benefit recent topical researches and applications for graphene as electrode material integrated in various semiconductor devices.

  12. Photocapacitance study of type-II GaSb/GaAs quantum ring solar cells

    SciTech Connect (OSTI)

    Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Carrington, P. J.; Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2014-01-07T23:59:59.000Z

    In this study, the density of states associated with the localization of holes in GaSb/GaAs quantum rings are determined by the energy selective charging of the quantum ring distribution. The authors show, using conventional photocapacitance measurements, that the excess charge accumulated within the type-II nanostructures increases with increasing excitation energies for photon energies above 0.9?eV. Optical excitation between the localized hole states and the conduction band is therefore not limited to the ?(k?=?0) point, with pseudo-monochromatic light charging all states lying within the photon energy selected. The energy distribution of the quantum ring states could consequently be accurately related from the excitation dependence of the integrated photocapacitance. The resulting band of localized hole states is shown to be well described by a narrow distribution centered 407?meV above the GaAs valence band maximum.

  13. Efficiency enhancement of InGaN/GaN solar cells with nanostructures

    SciTech Connect (OSTI)

    Bai, J.; Yang, C. C.; Athanasiou, M.; Wang, T. [Department of Electronics and Electrical Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2014-02-03T23:59:59.000Z

    We demonstrate InGaN/GaN multi-quantum-well solar cells with nanostructures operating at a wavelength of 520?nm. Nanostructures with a periodic nanorod or nanohole array are fabricated by means of modified nanosphere lithography. Under 1 sun air-mass 1.5 global spectrum illumination, a fill factor of 50 and an open circuit voltage of 1.9?V are achieved in spite of very high indium content in InGaN alloys usually causing degradation of crystal quality. Both the nanorod array and the nanohole array significantly improve the performance of solar cells, while a larger enhancement is observed for the nanohole array, where the conversion efficiency is enhanced by 51%.

  14. Intersubband absorption in AlN/GaN/AlGaN coupled quantum wells

    SciTech Connect (OSTI)

    Driscoll, Kristina; Bhattacharyya, Anirban; Moustakas, Theodore D.; Paiella, Roberto; Zhou, Lin; Smith, David J. [Department of Electrical and Computer Engineering and Photonics Center, Boston University, 8 Saint Mary's Street, Boston, Massachusetts 02215 (United States); Department of Physics and School of Materials, Arizona State University, Tempe, Arizona 85287 (United States)

    2007-10-01T23:59:59.000Z

    AlN/GaN/AlGaN coupled quantum wells grown by molecular beam epitaxy have been developed and characterized via intersubband absorption spectroscopy. In these structures, an AlGaN layer of sufficiently low Al content is used to achieve strong interwell coupling without the need for ultrathin inner barriers. At the same time, AlN is used in the outer barriers to provide the large quantum confinement required for near-infrared intersubband transitions. The composition of the inner barriers also provides a continuously tunable parameter to control the coupling strength. Double intersubband absorption peaks are measured in each sample, at photon energies in good agreement with theoretical expectations.

  15. GaN based nanorods for solid state lighting

    SciTech Connect (OSTI)

    Li Shunfeng; Waag, Andreas [Institute of Semiconductor Technology, Braunschweig University of Technology, 38106 Braunschweig (Germany)

    2012-04-01T23:59:59.000Z

    In recent years, GaN nanorods are emerging as a very promising novel route toward devices for nano-optoelectronics and nano-photonics. In particular, core-shell light emitting devices are thought to be a breakthrough development in solid state lighting, nanorod based LEDs have many potential advantages as compared to their 2 D thin film counterparts. In this paper, we review the recent developments of GaN nanorod growth, characterization, and related device applications based on GaN nanorods. The initial work on GaN nanorod growth focused on catalyst-assisted and catalyst-free statistical growth. The growth condition and growth mechanisms were extensively investigated and discussed. Doping of GaN nanorods, especially p-doping, was found to significantly influence the morphology of GaN nanorods. The large surface of 3 D GaN nanorods induces new optical and electrical properties, which normally can be neglected in layered structures. Recently, more controlled selective area growth of GaN nanorods was realized using patterned substrates both by metalorganic chemical vapor deposition (MOCVD) and by molecular beam epitaxy (MBE). Advanced structures, for example, photonic crystals and DBRs are meanwhile integrated in GaN nanorod structures. Based on the work of growth and characterization of GaN nanorods, GaN nanoLEDs were reported by several groups with different growth and processing methods. Core/shell nanoLED structures were also demonstrated, which could be potentially useful for future high efficient LED structures. In this paper, we will discuss recent developments in GaN nanorod technology, focusing on the potential advantages, but also discussing problems and open questions, which may impose obstacles during the future development of a GaN nanorod based LED technology.

  16. Reduction of gap states of ternary IIIV semiconductor surfaces by sulfur passivation: Comparative studies of AlGaAs and InGaP

    E-Print Network [OSTI]

    Kim, Sehun

    studies of AlGaAs and InGaP J. M. Seo School of Physics and Technology, Jeonbuk National University on liquid-phase-epitaxy-grown n-type InGaP and AlGaAs surfaces have been studied using x-ray photoelectron treatment in air. For InGaP, sulfur atoms initially reacted with both surface In and Ga atoms and reacted

  17. In0.6Ga0.4AsGaAs quantum-dot infrared photodetector with operating temperature up to 260 K

    E-Print Network [OSTI]

    Florida, University of

    the large band gap material such as AlGaAs or InGaP as blocking barrier to reduce the device dark current 100 K by us- ing a large band gap material such as AlGaAs or InGaP as the blocking barrier to reduce temperature up to 260 K without using the wide band gap AlGaAs or InGaP current blocking bar- rier. The sample

  18. Phase-locking of an InP/InGaP/InGaAs resonant tunneling diode relaxation oscillator by direct optical injection

    E-Print Network [OSTI]

    Eisenstein, Gadi

    Phase-locking of an InP/InGaP/InGaAs resonant tunneling diode relaxation oscillator by direct relaxation oscillator is demonstrated. The diode is an Al-free InP/InGaP/InGaAs structure in the InP/InGaAs/InGaP aluminum-free material system, following the work of Cohen and Ritter [6

  19. Simultaneous enhancement of electron overflow reduction and hole injection promotion by tailoring the last quantum barrier in InGaN/GaN light-emitting diodes

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    the last quantum barrier in InGaN/GaN light-emitting diodes Zabu Kyaw, Zi-Hui Zhang, Wei Liu, Swee Tiam Tan injection and efficiency droop in InGaN/GaN light-emitting diodes with step-stage multiple- quantum distribution in InGaN/GaN light-emitting diodes with graded thickness quantum barriers Appl. Phys. Lett. 102

  20. IEEE ELECTRON DEVICE LETTERS, VOL. 21, NO. 12, DECEMBER 2000 549 Dual-Gate AlGaN/GaN Modulation-Doped

    E-Print Network [OSTI]

    Rodwell, Mark J. W.

    IEEE ELECTRON DEVICE LETTERS, VOL. 21, NO. 12, DECEMBER 2000 549 Dual-Gate AlGaN/GaN Modulation--We demonstrate dual-gate AlGaN/GaN modula- tion-doped field-effect transistors (MODFETs) with gate-lengths of 0 power amplifiers. Index Terms--AlGaN/GaN, broadband power amplifiers, dual-gate FETs. I. INTRODUCTION

  1. Graded-base InGaN/GaN heterojunction bipolar light-emitting transistors B. F. Chu-Kung,a

    E-Print Network [OSTI]

    Asbeck, Peter M.

    Graded-base InGaN/GaN heterojunction bipolar light-emitting transistors B. F. Chu-Kung,a M. Feng, G; published online 25 August 2006 The authors report radiative recombination from a graded-base InGaN/GaN microwave power has been obtained from GaN field-effect transistors, very few operational GaN-based HBTs

  2. InGaN/GaN multiple-quantum-well light-emitting diodes with a grading InN composition suppressing the Auger recombination

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    InGaN/GaN multiple-quantum-well light-emitting diodes with a grading InN composition suppressing://scitation.aip.org/content/aip/journal/apl/105/3?ver=pdfcov Published by the AIP Publishing Articles you may be interested in High efficiency InGaN/GaN (2014); 10.1063/1.4867023 Effect of V-defects on the performance deterioration of InGaN/GaN multiple

  3. Polarized emission lines from A-and B-type excitonic complexes in single InGaN/GaN quantum dots

    E-Print Network [OSTI]

    Nabben, Reinhard

    Polarized emission lines from A- and B-type excitonic complexes in single InGaN/GaN quantum dots M Cathodoluminescence measurements on single InGaN/GaN quantum dots QDs are reported. Complex spectra with up to five spectral region have been realized based on InGaN structures.1 Single-photon emission from GaN/AlN quantum

  4. Fabry-Perot effects in InGaN/GaN heterostructures on Si-substrate C. Hums, T. Finger, T. Hempel, J. Christen, and A. Dadgara

    E-Print Network [OSTI]

    Nabben, Reinhard

    Fabry-Perot effects in InGaN/GaN heterostructures on Si-substrate C. Hums, T. Finger, T. Hempel, J spectra of InGaN/GaN heterostructures and quantum wells epitaxially grown on Si 111 substrates. This Fabry-Perot effect results from the high refractive index contrasts at the GaN/Si and the Air/InGaN interfaces

  5. Determination of two-dimensional electron and hole gas carriers in AlGaN/GaN/AlN heterostructures grown by Metal

    E-Print Network [OSTI]

    Ozbay, Ekmel

    on nominally undoped Al0.25Ga0.75N/GaN/AlN heterostructures grown on sapphire substrates prepared by metal undoped Al0.25Ga0.75N/GaN/ AlN heterostructures grown on sapphire substrate. © 2007 Elsevier B.V. All of AlGaN on a thick GaN epilayer on a semi- insulating substrate. Spontaneous and strain induced

  6. Nonpolar cubic AlGaN/GaN heterojunction field-effect transistor on Ar+ implanted 3CSiC ,,001...

    E-Print Network [OSTI]

    As, Donat Josef

    through the substrate. Cubic AlGaN/GaN heterostructures were grown in a RibeNonpolar cubic AlGaN/GaN heterojunction field-effect transistor on Ar+ implanted 3C­SiC ,,001... E HFET was fabricated of nonpolar cubic AlGaN/GaN grown on Ar+ implanted 3C­SiC 001 by molecular beam

  7. On the mechanisms of InGaN electron cooler in InGaN/GaN light-emitting diodes

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    . Schubert, Q. Dai, J. K. Kim, E. F. Schubert, J. Piprek, and Y. Park, "Origin of efficiency droop in Ga. Tansu, "Current injection efficiency induced efficiency-droop in InGaN quantum well light. Van de Walle, "Indirect Auger recombination as a cause of efficiency droop in nitride light

  8. Generation and transportation mechanisms for two-dimensional hole gases in GaN/AlGaN/GaN double heterostructures

    SciTech Connect (OSTI)

    Nakajima, Akira, E-mail: a-nakajima@aist.go.jp; Ogura, Masahiko; Makino, Toshiharu; Nishizawa, Shin-ichi; Ohashi, Hiromichi; Yamasaki, Satoshi [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Central 2, 1-1-1 Umezono, Tsukuba 305-8568 (Japan); Liu, Pucheng; Kakushima, Kuniyuki; Iwai, Hiroshi [Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori, Yokohama, Kanagawa 226-8503 (Japan)

    2014-04-21T23:59:59.000Z

    The electrical properties of two-dimensional hole gases (2DHGs) in GaN/AlGaN/GaN double heterostructures were investigated. The layers were grown on sapphire substrates and a high-quality bulk GaN substrate. The coexistence of 2DHG and 2D electron gases on both sides of the AlGaN layer was confirmed by Hall effect measurements at 80–460?K. It was also verified that the 2DHGs were generated by negative polarization at the undoped GaN/AlGaN interface, which did not have a doped Mg acceptor. It was also demonstrated that the 2DHG density could be controlled by varying the AlGaN layer thickness and was inversely related to the 2DHG mobility. The measured relation indicated that the 2DHG mobility is mainly limited by phonon scatterings at around room temperature. As a result, the maximum 2DHG mobility of 16 cm{sup 2}/Vs at 300?K was achieved with a density of 1?×?10{sup 13}?cm{sup ?2}.

  9. Temperature dependency of the emission properties from positioned In(Ga)As/GaAs quantum dots

    SciTech Connect (OSTI)

    Braun, T.; Schneider, C.; Maier, S.; Forchel, A.; Höfling, S.; Kamp, M. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Röntgen-Research Center for Complex Material Systems, Universität Würzburg, Am Hubland, D-97074, Würzburg (Germany); Igusa, R.; Iwamoto, S.; Arakawa, Y. [University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

    2014-09-15T23:59:59.000Z

    In this letter we study the influence of temperature and excitation power on the emission linewidth from site-controlled InGaAs/GaAs quantum dots grown on nanoholes defined by electron beam lithography and wet chemical etching. We identify thermal electron activation as well as direct exciton loss as the dominant intensity quenching channels. Additionally, we carefully analyze the effects of optical and acoustic phonons as well as close-by defects on the emission linewidth by means of temperature and power dependent micro-photoluminescence on single quantum dots with large pitches.

  10. Origins of ion irradiation-induced Ga nanoparticle motion on GaAs surfaces

    SciTech Connect (OSTI)

    Kang, M.; Wu, J. H.; Chen, H. Y.; Thornton, K.; Goldman, R. S. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States)] [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Sofferman, D. L. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States) [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Department of Physics, Adelphi University, Garden City, New York 11530-0701 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

    2013-08-12T23:59:59.000Z

    We have examined the origins of ion irradiation-induced nanoparticle (NP) motion. Focused-ion-beam irradiation of GaAs surfaces induces random walks of Ga NPs, which are biased in the direction opposite to that of ion beam scanning. Although the instantaneous NP velocities are constant, the NP drift velocities are dependent on the off-normal irradiation angle, likely due to a difference in surface non-stoichiometry induced by the irradiation angle dependence of the sputtering yield. It is hypothesized that the random walks are initiated by ion irradiation-induced thermal fluctuations, with biasing driven by anisotropic mass transport.

  11. Wavelength limits for InGaN quantum wells on GaN

    SciTech Connect (OSTI)

    Pristovsek, Markus, E-mail: markus@pristovsek.de [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)] [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom)

    2013-06-17T23:59:59.000Z

    The emission wavelength of coherently strained InGaN quantum wells (QW) is limited by the maximum thickness before relaxation starts. For high indium contents x>40% the resulting wavelength decreases because quantum confinement dominates. For low indium content x<40% the electron hole wave function overlap (and hence radiative emission) is strongly reduced with increasing QW thickness due to the quantum confined Stark effect and imposes another limit. This results in a maximum usable emission wavelength at around 600?nm for QWs with 40%-50% indium content. Relaxed InGaN buffer layers could help to push this further, especially on non- and semi-polar orientations.

  12. Application of the ASME code in the design of the GA-4 and GA-9 casks

    SciTech Connect (OSTI)

    Mings, W.J. (USDOE Idaho Field Office, Idaho Falls, ID (United States)); Koploy, M.A. (General Atomics, San Diego, CA (United States))

    1992-01-01T23:59:59.000Z

    General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

  13. Application of the ASME code in the design of the GA-4 and GA-9 casks

    SciTech Connect (OSTI)

    Mings, W.J. [USDOE Idaho Field Office, Idaho Falls, ID (United States); Koploy, M.A. [General Atomics, San Diego, CA (United States)

    1992-08-01T23:59:59.000Z

    General Atomics (GA) is developing two spent fuel shipping casks for transport by legal weight truck (LWT). The casks are designed to the loading, environmental conditions and safety requirements defined in Title 10 of the Code of Federal Regulations, Part 71 (10CFR71). To ensure that all components of the cask meet the 10CFR71 rules, GA established structural design criteria for each component based on NRC Regulatory Guides and the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). This paper discusses the criteria used for different cask components, how they were applied and the conservatism and safety margins built into the criteria and assumption.

  14. Two-color picosecond and continuous-wave experiments on anti-Stokes and Stokes carrier-transfer phenomena in GaAs/AlxGa1 xAs and InGaP2 /AlxGa1 xAs heterostructures

    E-Print Network [OSTI]

    Hohng, Sung Chul

    -transfer phenomena in GaAs/AlxGa1 xAs and InGaP2 /AlxGa1 xAs heterostructures S. C. Hohng, D. W. Khang, Y. H. Ahn, J evidence of the two-step absorption process in anti-Stokes photoluminescence in both GaAs/AlxGa1 xAs and InGaP

  15. Improved Quality Control Processing of Peptide-centric LC-MS...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Quality Control Processing of Peptide-centric LC-MS Proteomics Data. Improved Quality Control Processing of Peptide-centric LC-MS Proteomics Data. Abstract: In the analysis of...

  16. A Top-Down LC-FTICR MS-Based Strategy for Characterizing Oxidized...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Top-Down LC-FTICR MS-Based Strategy for Characterizing Oxidized Calmodulin in Activated Macrophages . A Top-Down LC-FTICR MS-Based Strategy for Characterizing Oxidized Calmodulin...

  17. FT-ICR MS optimization for the analysis of intact proteins. ...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    FT-ICR MS optimization for the analysis of intact proteins. FT-ICR MS optimization for the analysis of intact proteins. Abstract: Fourier-transform ion cyclotron resonance (FT-ICR)...

  18. Demonstration of a semipolar (10(1)over-bar(3)over-bar) InGaN/GaN green light emitting diode

    E-Print Network [OSTI]

    2005-01-01T23:59:59.000Z

    InGaN / GaN green light emitting diode R. Sharma, a? P. M.green ??525 nm? light emitting diode ?LED?. The fabricated

  19. Distributed bragg reflector using AIGaN/GaN

    DOE Patents [OSTI]

    Waldrip, Karen E.; Lee, Stephen R.; Han, Jung

    2004-08-10T23:59:59.000Z

    A supported distributed Bragg reflector or superlattice structure formed from a substrate, a nucleation layer deposited on the substrate, and an interlayer deposited on the nucleation layer, followed by deposition of (Al,Ga,B)N layers or multiple pairs of (Al,Ga,B)N/(Al,Ga,B)N layers, where the interlayer is a material selected from AlN, Al.sub.x Ga.sub.1-x N, and AlBN with a thickness of approximately 20 to 1000 angstroms. The interlayer functions to reduce or eliminate the initial tensile growth stress, thereby reducing cracking in the structure. Multiple interlayers utilized in an AlGaN/GaN DBR structure can eliminate cracking and produce a structure with a reflectivity value greater than 0.99.

  20. Ion-beam-induced chemical disorder in GaN

    SciTech Connect (OSTI)

    Ishimaru, Manabu; Zhang, Yanwen; Weber, William J.

    2009-09-08T23:59:59.000Z

    Atomistic structures of high-energy ion irradiated GaN have been examined using transmission electron microscopy (TEM). Single crystalline GaN substrates were irradiated at cryogenic temperature with 2 MeV Au2+ ions to a fluence of 7.35x1015 Au/cm2. Cross-sectional TEM observations revealed that damaged layers consisting of amorphous and nanocrystalline phases are formed at the surface and buried depth of the as-irradiated GaN substrate. Atomic radial distribution functions of the amorphous/poly-nanocrystalline regions showed that not only heteronuclear Ga-N bonds but also homonuclear Ga-Ga bonds exist within the first coordination shell. It was found that the ratio of heteronuclear-to-homonuclear bonds, i.e., the degree of chemical disorder is different between the surface and buried damaged layers. The alternation of chemical disorder was attributed to the difference in the defect formation processes between these layers.

  1. Effects of the anesthesia agents benozocaine and tricaine methanesulfonate (MS-222) on

    E-Print Network [OSTI]

    Kane, Andrew S.

    1 Effects of the anesthesia agents benozocaine and tricaine methanesulfonate (MS-222) on immune anesthesia ­ 10 min MS-222 ­ 14 min benzocaine #12;3 Materials and Methods Control Rinse MS-222 Benzocaine Control Anesthesia Recovery ASW ASW Aquaria 7 days Materials and Methods: Experiment 1 · Blood collection

  2. Aerospace Engineering Aircraft and Spacecraft Design BS, MS Space Transportation and Exploration

    E-Print Network [OSTI]

    Su, Xiao

    Engineering BS, MS Chemical Engineering Biotechnology BS, MS Environmental Health and Safety Semiconductors and Polymers Processing Civil Engineering Construction BS, MS Environmental Geotechnical Structural and Environmental Engineering 408-924-3900 www.cee.sjsu.edu Computer Engineering 408-924-4150 www

  3. Mini-Project Assignment: MS2a Bioinformatics and Computational Biology

    E-Print Network [OSTI]

    Goldschmidt, Christina

    1 Mini-Project Assignment: MS2a Bioinformatics and Computational Biology Deadline TWO COPIES of your completed mini-project for MS2a Bioinformatics and Computational Biology should be handed-project assignment are on pages 2-4 below. #12;2 Mini-Project Assignment: MS2a Bioinformatics and Computational

  4. Radiation Hard AlGaN Detectors and Imager

    SciTech Connect (OSTI)

    None

    2012-05-01T23:59:59.000Z

    Radiation hardness of AlGaN photodiodes was tested using a 65 MeV proton beam with a total proton fluence of 3x10{sup 12} protons/cm{sup 2}. AlGaN Deep UV Photodiode have extremely high radiation hardness. These new devices have mission critical applications in high energy density physics (HEDP) and space explorations. These new devices satisfy radiation hardness requirements by NIF. NSTec is developing next generation AlGaN optoelectronics and imagers.

  5. O?[]O? nuclear ?-decay of ?²Ga

    E-Print Network [OSTI]

    Hyman, Bruce Carl

    1999-01-01T23:59:59.000Z

    information, MARS was focused such that only fully stripped N=Z ions were passed, with the vast majority of them being Ga. The second phase of the experiment was a I3-y coincidence experiment. At the back-end of MARS, a 1" x 1 '!4" x 3" four..., using the Weinberg-Salam model of electroweak interactions, to be [23]: A& ? d, ?= ? [41n(mz/m )+ln(m /m?)+2K+A +" ]. (16) Here mz is the mass of the Z boson, me the proton mass, mx is the low energy cutoff for the second and third terms that arise...

  6. P-type doping of GaN

    SciTech Connect (OSTI)

    Wong, R.K.

    2000-04-10T23:59:59.000Z

    After implantation of As, As + Be, and As + Ga into GaN and annealing for short durations at temperatures as high as 1500 C, the GaN films remained highly resistive. It was apparent from c-RBS studies that although implantation damage did not create an amorphous layer in the GaN film, annealing at 1500 C did not provide enough energy to completely recover the radiation damage. Disorder recovered significantly after annealing at temperatures up to 1500 C, but not completely. From SIMS analysis, oxygen contamination in the AIN capping layer causes oxygen diffusion into the GaN film above 1400 C. The sapphire substrate (A1203) also decomposed and oxygen penetrated into the backside of the GaN layer above 1400 C. To prevent donor-like oxygen impurities from the capping layer and the substrate from contaminating the GaN film and compensating acceptors, post-implantation annealing should be done at temperatures below 1500 C. Oxygen in the cap could be reduced by growing the AIN cap on the GaN layer after the GaN growth run or by depositing the AIN layer in a ultra high vacuum (UHV) system post-growth to minimize residual oxygen and water contamination. With longer annealing times at 1400 C or at higher temperatures with a higher quality AIN, the implantation drainage may fully recover.

  7. Segregation of In to dislocations in InGaN

    E-Print Network [OSTI]

    Horton, Matthew K.; Rhode, Sneha; Sahonta, Suman-Lata; Kappers, Menno J.; Haigh, Sarah J.; Pennycook, Timothy J.; Humphreys, Colin J.; Dusane, Rajiv O.; Moram, Michelle A.

    2015-01-16T23:59:59.000Z

    .; Fischer, A. J.; Thaler, G.; Banas, M. A. Effect of dislocation density on efficiency droop in GaInN?GaN light-emitting diodes. Applied Physics Letters 2007, 91, 231114 DOI: 10.1063/1.2822442. (3) Schubert, M. F.; Xu, J.; Kim, J. K.; Schubert, E. F.; Kim... , M. H.; Yoon, S.; Lee, S. M.; Sone, C.; Sakong, T.; Park, Y. Polarization-matched GaInN?AlGaInN multi-quantum-well light-emitting diodes with reduced efficiency droop. Applied Physics Letters 2008, 93, 041102 DOI: 10.1063/1.2963029. (4) Hsu, J. W. P...

  8. Surface Science Analysis of GaAs Photocathodes Following Sustained...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery. Abstract: Degradation of the photocathode materials employed in photoinjectors represents a challenge for...

  9. Self-aligned InGaP/GaAs heterojunction bipolar transistors for microwave power application

    SciTech Connect (OSTI)

    Ren, F.; Abernathy, C.R.; Pearton, S.J.; Lothian, J.R.; Wisk, P.W.; Fullowan, T.R.; Youngkai Chen (AT and T Bell Labs., Murray Hill, NJ (United States)); Yang, L.W.; Fu, S.T.; Brozovich, R.S. (General Electric Co., Syracuse, NY (USSR))

    1993-07-01T23:59:59.000Z

    As an alternative to AlGaAs/GaAs heterojunction bipolar transistors (HBT's) for microwave applications, InGaP/ GaAs HBT's with carbon-doped base layers grown by metal organic molecular beam epitaxy (MOMBE) are demonstrated with excellent dc, RF, and microwave performance. As previously reported, with a 700-[angstrom]-thick base layer (135-[Omega]/[open square] sheet resistance), a dc current gain of 25, and cutoff frequency and maximum frequency of oscillation above 70 GHz were measured for a 2 [times] 5-[mu]m[sup 2] emitter area device. A device with 12 cells, each consisting of a 2 [times] 15-[mu] m[sup 2] emitter area device for a total emitter area of 360 [mu] m[sup 2], was power tested at 4 GHz under continuous-wave (CW) bias condition. The device delivered 0.6-W output power with 13-dB linear gain and a power-added efficiency of 50%.

  10. High efficiency InGaN/GaN light emitting diodes with asymmetric triangular multiple quantum wells

    SciTech Connect (OSTI)

    Chang, Chiao-Yun; Li, Hen; Lu, Tien-Chang, E-mail: timtclu@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 University Road, Hsinchu, Taiwan 300 (China)

    2014-03-03T23:59:59.000Z

    In this study, we demonstrated high efficiency InGaN/GaN light emitting diodes (LEDs) with asymmetric triangular multiple quantum wells (MQWs). Asymmetric triangular MQWs not only contribute to uniform carrier distribution in InGaN/GaN MQWs but also yield a low Auger recombination rate. In addition, asymmetric triangular MQWs with gallium face-oriented inclination band profiles can be immune from the polarization charge originating from typical c-plane InGaN/GaN quantum well structures. In the experiment, LEDs incorporated with asymmetric triangular MQWs with gallium face-oriented inclination band profiles exhibited a 60.0% external quantum efficiency at 20?mA and a 27.0% efficiency droop at 100?mA (corresponding to a current density of 69?A/cm{sup 2}), which accounted for an 11.7% efficiency improvement and a 31.1% droop reduction compared with symmetric square quantum well structure LEDs.

  11. Influence of substrate quality on structural properties of AlGaN/GaN superlattices grown by molecular beam epitaxy

    SciTech Connect (OSTI)

    Schubert, F. [NaMLab gGmbH, Nöthnitzer Straße 64, 01187 Dresden (Germany); Merkel, U.; Schmult, S. [TU Dresden, Institute of Semiconductors and Microsystems, Nöthnitzer Straße 64, 01187 Dresden (Germany); Mikolajick, T. [NaMLab gGmbH, Nöthnitzer Straße 64, 01187 Dresden (Germany); TU Dresden, Institute of Semiconductors and Microsystems, Nöthnitzer Straße 64, 01187 Dresden (Germany)

    2014-02-28T23:59:59.000Z

    Short-period AlGaN/GaN superlattices were established as versatile test structures to investigate the structural properties of molecular beam epitaxy (MBE)-grown GaN and AlGaN layers and their dependence on the GaN substrate quality. X-ray diffractometry data of the investigated superlattices allow access to relevant structural parameters such as aluminum mole fraction and layer thicknesses. The occurrence of theoretically predicted intense high-order satellite peaks and pronounced interface fringes in the diffraction pattern reflects abrupt interfaces and perfect 2-dimensional growth resulting in smooth surfaces. The data unambiguously demonstrate that the structural quality of the MBE grown layers is limited by the structural properties of the GaN substrate.

  12. Ferromagnetic semiconductors based upon AlGaP M. E. Overberg,a)

    E-Print Network [OSTI]

    Hebard, Arthur F.

    band-gap ternary InGaP, which is lattice matched to GaAs. An immediate application of the DMS, with its wide band-gap binary GaP, AlP and ternary InGaP, AlGaP, AlInP components, is used for devices

  13. ARM - Campaign Instrument - pyran-eko-ms-801

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625 1,006 492air Comments? We would love to hear from you!jplcarter-scott Comments? We would love to heareko-ms-801

  14. Pole- versus MS-mass definitions in the electroweak theory

    E-Print Network [OSTI]

    M. Faisst; J. H. Kuhn; O. Veretin

    2004-03-16T23:59:59.000Z

    Two different two-loop relations between the pole- and the MS-mass of the top quark have been derived in the literature which were based on different treatments of the tadpole diagrams. In addition, the limit M_W^2/m_t^2 \\to 0 was employed in one of the calculations. It is shown that, after appropriate transformations, the results of the two calculations are in perfect agreement. Furthermore we demonstrate that the inclusion of the non-vanishing mass of the W-boson leads to small modifications only.

  15. Bioenergia Brasil S A MS | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page onYou are now leaving Energy.gov You are now leaving Energy.gov You are being directedAnnual Siteof EnergyInnovation in Carbonof AlternativeBioenergia Brasil S A MS Jump to:

  16. Radiation response of single and dual junction p{sup +}n InGaP/GaAs space solar cells

    SciTech Connect (OSTI)

    Walters, R.J.; Xapsos, M.A.; Summers, G.P. [Naval Research Lab., Washington, DC (United States); Cotal, H.L.; Messenger, S.R. [SFA, Inc., Largo, MD (United States)

    1997-12-31T23:59:59.000Z

    The radiation response of single and dual-junction p{sup +}n InGaP/GaAs solar cells is studied. The degradation mechanisms of single-junction InGaP cells are identified, and characteristic degradation curves in terms of displacement damage dose are calculated. The response of dual-junction cells is presented, and the response of each sub-cell is discussed. The cell response is compared with those of other technologies. The effect of current injection on irradiated InGaP cell is presented.

  17. DC characteristics of OMVPE-grown N-p-n InGaP/InGaAsN DHBTs

    SciTech Connect (OSTI)

    Li, N.Y.; Chang, P.C.; Baca, A.G.; Xie, X.M.; Sharps, P.R.; Hou, H.Q.

    2000-01-04T23:59:59.000Z

    The authors demonstrate, for the first time, a functional N-p-n heterojunction bipolar transistor using a novel material, InGaAsN, with a bandgap energy of 1.2eV as the p-type base layer. A 300{angstrom}-thick In{sub x}Ga{sub 1-x}As graded layer was introduced to reduce the conduction band offset at the p-type InGaAsN base and n-type GaAs collector junction. For an emitter size of 500 {mu}m{sup 2}, a peak current gain of 5.3 has been achieved.

  18. Surface donor states distribution post SiN passivation of AlGaN/GaN heterostructures

    SciTech Connect (OSTI)

    Goyal, Nitin, E-mail: nitin@unik.no [Carinthian Tech Research CTR AG, Europastraße 4/1, Technologiepark Villach, A- 9524 Villach/St. Magdalen (Austria); Department of Electronics and Telecommunication, Norwegian University of Science and Technology, Trondheim NO7034 (Norway); Fjeldly, Tor A. [Department of Electronics and Telecommunication, Norwegian University of Science and Technology, Trondheim NO7034 (Norway)

    2014-07-21T23:59:59.000Z

    In this paper, we present a physics based analytical model to describe the effect of SiN passivation on two-dimensional electron gas density and surface barrier height in AlGaN/GaN heterostructures. The model is based on an extraction technique to calculate surface donor density and surface donor level at the SiN/AlGaN interface. The model is in good agreement with the experimental results and promises to become a useful tool in advanced design and characterization of GaN based heterostructures.

  19. Free-standing AlxGa1-xAs heterostructures by gas-phase etching of germanium

    E-Print Network [OSTI]

    As compounds encompassing low aluminum content AlGaAs, InGaAs, InGaP, etc. , typi- cally, a sacrificial Al

  20. Reliability of AlGaN/GaN high electron mobility transistors on low dislocation density bulk GaN substrate: Implications of surface step edges

    SciTech Connect (OSTI)

    Killat, N., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk; Montes Bajo, M.; Kuball, M., E-mail: Nicole.Killat@bristol.ac.uk, E-mail: Martin.Kuball@bristol.ac.uk [Center for Device Thermography and Reliability (CDTR), H.H. Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Paskova, T. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States) [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Materials Science and Engineering Department, North Carolina State University, Raleigh, North Carolina 27695 (United States); Evans, K. R. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States)] [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Leach, J. [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States) [Kyma Technologies, Inc., Raleigh, North Carolina 27617 (United States); Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Li, X.; Özgür, Ü.; Morkoç, H. [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)] [Electrical and Computer Engineering Department, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Chabak, K. D.; Crespo, A.; Gillespie, J. K.; Fitch, R.; Kossler, M.; Walker, D. E.; Trejo, M.; Via, G. D.; Blevins, J. D. [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)] [Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433 (United States)

    2013-11-04T23:59:59.000Z

    To enable gaining insight into degradation mechanisms of AlGaN/GaN high electron mobility transistors, devices grown on a low-dislocation-density bulk-GaN substrate were studied. Gate leakage current and electroluminescence (EL) monitoring revealed a progressive appearance of EL spots during off-state stress which signify the generation of gate current leakage paths. Atomic force microscopy evidenced the formation of semiconductor surface pits at the failure location, which corresponds to the interaction region of the gate contact edge and the edges of surface steps.

  1. Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii, R. Deblock, B. Reulet, and H. Bouchiat

    E-Print Network [OSTI]

    Shepelyansky, Dima

    Mesoscopic photovoltaic effect in GaAs/Ga1-xAlxAs Aharonov-Bohm rings L. Angers, A. Chepelianskii specific dc voltage. We have investigated this photovoltaic PV effect on GaAs/Ga1-xAlxAs Aharonov is generally done by measuring the dc induced signal sometimes called photovoltaic effect which has also given

  2. GROWTH OF GaN ON POROUS SiC AND GaN SUBSTRATES C. K. Inoki and T. S. Kuan

    E-Print Network [OSTI]

    Feenstra, Randall

    1 GROWTH OF GaN ON POROUS SiC AND GaN SUBSTRATES C. K. Inoki and T. S. Kuan Department of Physics Institute, University of Illinois, Urbana, IL 61801 ABSTRACT We have studied the growth of GaN on porous SiC and GaN substrates, employing both plasma-assisted molecular beam epitaxy (PAMBE) and metalorganic

  3. GaN-based two-dimensional surface-emitting photonic crystal lasers with AlN/GaN distributed Bragg reflector

    E-Print Network [OSTI]

    Fan, Shanhui

    GaN-based two-dimensional surface-emitting photonic crystal lasers with AlN/GaN distributed Bragg 14 December 2007; published online 11 January 2008 GaN-based two-dimensional 2D surface-emitting photonic crystal PC lasers with AlN/GaN distributed Bragg reflectors are fabricated and demonstrated

  4. Dislocation and morphology control during molecular-beam epitaxy of AlGaN/GaN heterostructures directly on sapphire substrates

    E-Print Network [OSTI]

    Manfra, Michael J.

    Dislocation and morphology control during molecular-beam epitaxy of AlGaN/GaN heterostructures-dimensional arrays Appl. Phys. Lett. 100, 203117 (2012) Partially filled intermediate band of Cr-doped GaN films Appl at telecommunication wavelengths J. Appl. Phys. 111, 093721 (2012) GaN epitaxy on Cu(110) by metal organic chemical

  5. Collector-up light-emitting charge injection transistors in n-lnGaAs/lnAIAs/ plllnGaAs and n-lnGaAs/lnP/p-InGaAs heterostructures

    E-Print Network [OSTI]

    Luryi, Serge

    Collector-up light-emitting charge injection transistors in n-lnGaAs/lnAIAs/ plllnGaAs and n (Received 23 November 1992; accepted for publication 4 March 1993) The realization of collector-up light for the collector stripe definition. Electrons, injected over the wide-gap heterostructure barrier (InAlAs or In

  6. Free excitons in wurtzite GaN A. V. Rodina*

    E-Print Network [OSTI]

    Nabben, Reinhard

    Free excitons in wurtzite GaN A. V. Rodina* I. Physics Institute, Justus Liebig University in wurtzite GaN. Using polarization-dependent measurements we were able to resolve the fine-structure energy these data a theory is developed for the exciton energy structure in hexagonal semiconductors with wurtzite

  7. Ohmic contacts to p-type GaP

    E-Print Network [OSTI]

    Jorge Estevez, Humberto Angel

    1996-01-01T23:59:59.000Z

    was measured by the Cox-Strack method. Ohmic contacts based on the Zn/Pd system were developed. The Zn(350A)/Pd(IOOA)/p-GaP and Zn(350A)/Pd(IOOA)/p-GaP gave rather high values of the contact resistivity, 3-8xl 0-4 f2CM2. An improvement in the contact...

  8. The development of integrated chemical microsensors in GaAs

    SciTech Connect (OSTI)

    CASALNUOVO,STEPHEN A.; ASON,GREGORY CHARLES; HELLER,EDWIN J.; HIETALA,VINCENT M.; BACA,ALBERT G.; HIETALA,S.L.

    1999-11-01T23:59:59.000Z

    Monolithic, integrated acoustic wave chemical microsensors are being developed on gallium arsenide (GaAs) substrates. With this approach, arrays of microsensors and the high frequency electronic components needed to operate them reside on a single substrate, increasing the range of detectable analytes, reducing overall system size, minimizing systematic errors, and simplifying assembly and packaging. GaAs is employed because it is both piezoelectric, a property required to produce the acoustic wave devices, and a semiconductor with a mature microelectronics fabrication technology. Many aspects of integrated GaAs chemical sensors have been investigated, including: surface acoustic wave (SAW) sensors; monolithic SAW delay line oscillators; GaAs application specific integrated circuits (ASIC) for sensor operation; a hybrid sensor array utilizing these ASICS; and the fully monolithic, integrated SAW array. Details of the design, fabrication, and performance of these devices are discussed. In addition, the ability to produce heteroepitaxial layers of GaAs and aluminum gallium arsenide (AlGaAs) makes possible micromachined membrane sensors with improved sensitivity compared to conventional SAW sensors. Micromachining techniques for fabricating flexural plate wave (FPW) and thickness shear mode (TSM) microsensors on thin GaAs membranes are presented and GaAs FPW delay line and TSM resonator performance is described.

  9. Ohmic contacts to p-type Ga

    E-Print Network [OSTI]

    Jorge Estevez, Humberto Angel

    1996-01-01T23:59:59.000Z

    was measured by the Cox-Strack method. Ohmic contacts based on the Zn/Pd system were developed. The Zn(350A)/Pd(IOOA)/p-GaP and Zn(350A)/Pd(IOOA)/p-GaP gave rather high values of the contact resistivity, 3-8xl 0-4 f2CM2. An improvement in the contact...

  10. Polarized x-ray spectroscopy of quaternary ferromagnetic semiconductor (Ga,Mn)(As,P)

    E-Print Network [OSTI]

    Wadley, P.

    2011-01-01T23:59:59.000Z

    quaternary diluted magnetic semiconductor (Ga,Mn)(As,P) as aIn diluted magnetic semiconductors such as (Ga,Mn)As, whichquaternary diluted magnetic semiconductors such as (Ga,Mn)(

  11. Amorphization Processes in Au Ion Irradiated GaN at 150 - 300...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Processes in Au Ion Irradiated GaN at 150 - 300 K. Amorphization Processes in Au Ion Irradiated GaN at 150 - 300 K. Abstract: Epitaxial single-crystal gallium nitride (GaN) films...

  12. Damage Evolution in GaN Under MeV Heavy Ion Implantation. | EMSL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Evolution in GaN Under MeV Heavy Ion Implantation. Damage Evolution in GaN Under MeV Heavy Ion Implantation. Abstract: Damage evaluation processes in patterned GaN implanted by 3...

  13. Structural Defects in Laterally Overgrown GaN Layers Grown on Non-polar Substrates

    E-Print Network [OSTI]

    Liliental-Weber, Z.; Ni, X.; Morkoc, H.

    2007-01-01T23:59:59.000Z

    Overgrown GaN Layers Grown on Non-polar Substrates Z.in GaN layers grown on polar and non-polar substrates areGaN-based layers, since they are grown heteroepitaxially on foreign substrates (

  14. Imaging of InGaN inhomogeneities using visible apertureless near-field scanning optical microscope

    E-Print Network [OSTI]

    Stebounova, Larissa V.; Romanyuk, Yaroslav E.; Chen, Dongxue; Leone, Stephen R.

    2007-01-01T23:59:59.000Z

    InGaN dots deposited on a GaN substrate. 44 In that work, itGaN buffer layer is grown after the nitridation of the substrate.

  15. Mapping misorientation and crystallographic tilt in GaN layers via polychromatic microdiffraction

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    coefficients between GaN and the substrate. Understandingpenetrate both the GaN layer and the substrate. Two samplespattern from the GaN layer and the substrate on a charge-

  16. Selective epitaxial growth of monolithically integrated GaN-based light emitting diodes with AlGaN/GaN driving transistors

    SciTech Connect (OSTI)

    Liu, Zhaojun; Ma, Jun; Huang, Tongde; Liu, Chao; May Lau, Kei, E-mail: eekmlau@ust.hk [Photonics Technology Center, Department of Electronic and Computer Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2014-03-03T23:59:59.000Z

    In this Letter, we report selective epitaxial growth of monolithically integrated GaN-based light emitting diodes (LEDs) with AlGaN/GaN high-electron-mobility transistor (HEMT) drivers. A comparison of two integration schemes, selective epitaxial removal (SER), and selective epitaxial growth (SEG) was made. We found the SER resulted in serious degradation of the underlying LEDs in a HEMT-on-LED structure due to damage of the p-GaN surface. The problem was circumvented using the SEG that avoided plasma etching and minimized device degradation. The integrated HEMT-LEDs by SEG exhibited comparable characteristics as unintegrated devices and emitted modulated blue light by gate biasing.

  17. Elastic properties of Pu metal and Pu-Ga alloys

    SciTech Connect (OSTI)

    Soderlind, P; Landa, A; Klepeis, J E; Suzuki, Y; Migliori, A

    2010-01-05T23:59:59.000Z

    We present elastic properties, theoretical and experimental, of Pu metal and Pu-Ga ({delta}) alloys together with ab initio equilibrium equation-of-state for these systems. For the theoretical treatment we employ density-functional theory in conjunction with spin-orbit coupling and orbital polarization for the metal and coherent-potential approximation for the alloys. Pu and Pu-Ga alloys are also investigated experimentally using resonant ultrasound spectroscopy. We show that orbital correlations become more important proceeding from {alpha} {yields} {beta} {yields} {gamma} plutonium, thus suggesting increasing f-electron correlation (localization). For the {delta}-Pu-Ga alloys we find a softening with larger Ga content, i.e., atomic volume, bulk modulus, and elastic constants, suggest a weakened chemical bonding with addition of Ga. Our measurements confirm qualitatively the theory but uncertainties remain when comparing the model with experiments.

  18. Nucleation of GaN/AlN quantum dots

    SciTech Connect (OSTI)

    Adelmann, C; Daudin, B; Oliver, R; Briggs, G; Rudd, R

    2003-10-13T23:59:59.000Z

    We study the nucleation of GaN islands grown by plasma-assisted molecular-beam epitaxy on AlN in a Stranski-Krastanov mode. In particular, we assess the variation of their height and density as a function of GaN coverage. We show that the GaN growth passes four stages: initially, the growth is layer-by-layer; subsequently, bidimensional precursor islands form, which transform into genuine three-dimensional islands. During the latter stage, the height and the density of the islands increase with GaN coverage until the density saturates. During further GaN growth, the density remains constant and a bimodal height distribution appears. The variation of island height and density as a function of substrate temperature is discussed in the framework of an equilibrium model for Stranski-Krastanov growth [R. E. Rudd et al., Phys. Rev. Lett. 90, 146101 (2003)].

  19. Impact of GaN cap on charges in Al?O?/(GaN/)AlGaN/GaN metal-oxide-semiconductor heterostructures analyzed by means of capacitance measurements and simulations

    SciTech Connect (OSTI)

    ?apajna, M., E-mail: milan.tapajna@savba.sk; Jurkovi?, M.; Válik, L.; Haš?ík, Š.; Gregušová, D.; Kuzmík, J. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava (Slovakia); Brunner, F.; Cho, E.-M. [Ferdinand-Braun-Institut, Leibniz Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin (Germany); Hashizume, T. [Research Center for Integrated Quantum Electronics (RCIQE), Hokkaido University, 060-0814 Sapporo, Japan and JST-CREST, 102-0075 Tokyo (Japan)

    2014-09-14T23:59:59.000Z

    Oxide/semiconductor interface trap density (D{sub it}) and net charge of Al?O?/(GaN)/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistor (MOS-HEMT) structures with and without GaN cap were comparatively analyzed using comprehensive capacitance measurements and simulations. D{sub it} distribution was determined in full band gap of the barrier using combination of three complementary capacitance techniques. A remarkably higher D{sub it} (?5–8?×?10¹²eV?¹?cm?²) was found at trap energies ranging from EC-0.5 to 1?eV for structure with GaN cap compared to that (D{sub it}???2–3?×?10¹²eV?¹?cm?²) where the GaN cap was selectively etched away. D{sub it} distributions were then used for simulation of capacitance-voltage characteristics. A good agreement between experimental and simulated capacitance-voltage characteristics affected by interface traps suggests (i) that very high D{sub it} (>10¹³eV?¹?cm?²) close to the barrier conduction band edge hampers accumulation of free electron in the barrier layer and (ii) the higher D{sub it} centered about EC-0.6?eV can solely account for the increased C-V hysteresis observed for MOS-HEMT structure with GaN cap. Analysis of the threshold voltage dependence on Al?O? thickness for both MOS-HEMT structures suggests that (i) positive charge, which compensates the surface polarization, is not necessarily formed during the growth of III-N heterostructure, and (ii) its density is similar to the total surface polarization charge of the GaN/AlGaN barrier, rather than surface polarization of the top GaN layer only. Some constraints for the positive surface compensating charge are discussed.

  20. First principles phase diagram calculations for the wurtzitestructure systems AlN--GaN, GaN--InN, and AlN--InN

    E-Print Network [OSTI]

    Burton, Benjamin P.

    First principles phase diagram calculations for the wurtzite­structure systems AlN--GaN, GaN for the wurtzite­structure quasibinary systems AlN--GaN, GaN--InN, and AlN--InN. Cluster expansion Hamiltonians. Miscibility gaps are predicted for all three quasibinaries, with consolute points, #X C , T C #, for AlN--GaN

  1. AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers

    E-Print Network [OSTI]

    Jiang, Hongxing

    AlGaN/GaN/AlN quantum-well field-effect transistors with highly resistive AlN epilayers Z. Y. Fana 66506-2601 Received 23 November 2005; accepted 5 January 2006; published online 16 February 2006 AlGaN/GaN/AlN quantum-well field-effect transistors have been demonstrated. By replacing a semi-insulating GaN epilayer

  2. AlGaN/GaN MIS-HEMT Gate Structure Improvement Using Al2O3 Deposited by Plasma-Enhanced ALD

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    AlGaN/GaN MIS-HEMT Gate Structure Improvement Using Al2O3 Deposited by Plasma-Enhanced ALD R(0)438782894 Abstract - In this work we evaluate the influence of the Al2O3 ALD deposition technique on AlGaN/GaN MIS drastically reduced with a measured average of 1e-11 A/mm for a drain-source bias of 5V. 1. Introduction AlGaN

  3. Low Phase-Noise 5 GHz AlGaN/GaN HEMT Oscillator Integrated with BaxSr1-xTiO3 Thin Films

    E-Print Network [OSTI]

    York, Robert A.

    Low Phase-Noise 5 GHz AlGaN/GaN HEMT Oscillator Integrated with BaxSr1-xTiO3 Thin Films Hongtao Xu -- A C-band MMIC oscillator in GaN HEMT technology with BaxSr1-xTiO3 (BST) film capacitors integrated with the common gate HEMT to generate negative resistance. The oscillator, based on AlGaN/GaN HEMT with 0.7um gate

  4. Large linear magnetoresistance in a GaAs/AlGaAs heterostructure

    SciTech Connect (OSTI)

    Aamir, Mohammed Ali, E-mail: aamir@physics.iisc.ernet.in; Goswami, Srijit, E-mail: aamir@physics.iisc.ernet.in; Ghosh, Arindam [Department of Physics, Indian Institute of Science, Bangalore 560 012 (India); Baenninger, Matthias; Farrer, Ian; Ritchie, David A. [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Tripathi, Vikram [Department of Theoretical Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Pepper, Michael [Department of Electrical and Electronic Engineering, University College, London WC1E 7JE (United Kingdom)

    2013-12-04T23:59:59.000Z

    We report non-saturating linear magnetoresistance (MR) in a two-dimensional electron system (2DES) at a GaAs/AlGaAs heterointerface in the strongly insulating regime. We achieve this by driving the gate voltage below the pinch-off point of the device and operating it in the non-equilibrium regime with high source-drain bias. Remarkably, the magnitude of MR is as large as 500% per Tesla with respect to resistance at zero magnetic field, thus dwarfing most non-magnetic materials which exhibit this linearity. Its primary advantage over most other materials is that both linearity and the enormous magnitude are retained over a broad temperature range (0.3 K to 10 K), thus making it an attractive candidate for cryogenic sensor applications.

  5. Sidewall passivation for InGaN/GaN nanopillar light emitting diodes

    SciTech Connect (OSTI)

    Choi, Won Hyuck; Abraham, Michael; Yu, Shih-Ying [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); You, Guanjun; Liu, Jie; Wang, Li; Xu, Jian, E-mail: jianxu@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Mohney, Suzanne E., E-mail: mohney@ems.psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-07-07T23:59:59.000Z

    We studied the effect of sidewall passivation on InGaN/GaN multiquantum well-based nanopillar light emitting diode (LED) performance. In this research, the effects of varying etch rate, KOH treatment, and sulfur passivation were studied for reducing nanopillar sidewall damage and improving device efficiency. Nanopillars prepared under optimal etching conditions showed higher photoluminescence intensity compared with starting planar epilayers. Furthermore, nanopillar LEDs with and without sulfur passivation were compared through electrical and optical characterization. Suppressed leakage current under reverse bias and four times higher electroluminescence (EL) intensity were observed for passivated nanopillar LEDs compared with unpassivated nanopillar LEDs. The suppressed leakage current and EL intensity enhancement reflect the reduction of non-radiative recombination at the nanopillar sidewalls. In addition, the effect of sulfur passivation was found to be very stable, and further insight into its mechanism was gained through transmission electron microscopy.

  6. Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings

    SciTech Connect (OSTI)

    Wagener, M. C.; Botha, J. R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Carrington, P. J. [Department of Electronic and Electrical Engineering, University College London, London (United Kingdom); Krier, A. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)

    2014-07-28T23:59:59.000Z

    The optical parameters describing the sub-bandgap response of GaSb/GaAs quantum rings solar cells have been obtained from photocurrent measurements using a modulated pseudo-monochromatic light source in combination with a second, continuous photo-filling source. By controlling the charge state of the quantum rings, the photoemission cross-sections describing the two-photon sub-bandgap transitions could be determined independently. Temperature dependent photo-response measurements also revealed that the barrier for thermal hole emission from the quantum rings is significantly below the quantum ring localisation energy. The temperature dependence of the sub-bandgap photo-response of the solar cell is also described in terms of the photo- and thermal-emission characteristics of the quantum rings.

  7. Single photon emission from site-controlled InGaN/GaN quantum dots

    SciTech Connect (OSTI)

    Zhang, Lei; Hill, Tyler A.; Deng, Hui, E-mail: dengh@umich.edu [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States)] [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States); Teng, Chu-Hsiang; Lee, Leung-Kway; Ku, Pei-Cheng, E-mail: peicheng@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)] [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

    2013-11-04T23:59:59.000Z

    Single photon emission was observed from site-controlled InGaN/GaN quantum dots. The single-photon nature of the emission was verified by the second-order correlation function up to 90?K, the highest temperature to date for site-controlled quantum dots. Micro-photoluminescence study on individual quantum dots showed linearly polarized single exciton emission with a lifetime of a few nanoseconds. The dimensions of these quantum dots were well controlled to the precision of state-of-the-art fabrication technologies, as reflected in the uniformity of their optical properties. The yield of optically active quantum dots was greater than 90%, among which 13%–25% exhibited single photon emission at 10?K.

  8. High internal and external quantum efficiency InGaN/GaN solar cells

    SciTech Connect (OSTI)

    Matioli, Elison; Neufeld, C. J.; Iza, Michael; Cruz, S. C.; Al-Heji, Ali A.; Chen, Xu; Farrell, Rober M.; Keller, Stacia; DenBaars, Steven; Mishra, U. K.; Nakamura, Shuji; Speck, J. S.; Weisbuch, Claude

    2011-01-01T23:59:59.000Z

    High internal and external quantum efficiency GaN/InGaN solar cells are demonstrated. The internal quantum efficiency was assessed through the combination of absorption and external quantum efficiency measurements. The measured internal quantum efficiency, as high as 97%, revealed an efficient conversion of absorbed photons into electrons and holes and an efficient transport of these carriers outside the device. Improved light incoupling into the solar cells was achieved by texturing the surface. A peak external quantum efficiency of 72%, a fill factor of 79%, a short-circuit current density of 1.06?mA/cm{sup 2} , and an open circuit voltage of 1.89 V were achieved under 1 sun air-mass 1.5 global spectrumillumination conditions.

  9. Infrared reflection of GaN and AlGaN thin film heterostructures with AlN buffer layers

    E-Print Network [OSTI]

    Wetzel, Christian M.

    Infrared reflection of GaN and AlGaN thin film heterostructures with AlN buffer layers C. Wetzel, Nagoya, Japan Received 11 December 1995; accepted for publication 21 February 1996 Infrared reflection, their alloys and potential substrates need to be investigated as well. Here we present a study of the infrared

  10. Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes

    E-Print Network [OSTI]

    Wetzel, Christian M.

    Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes S. L. Rumyantseva well light emitting diodes. The light intensity noise was measured as a function of wavelength within the light emitting diode spectral emission line. The spectral noise density is found to increase

  11. Pulsed Current-Voltage-Temperature Characteristics of AlGaN/GaN High Electron Mobility Transistor under Isothermal Conditions

    E-Print Network [OSTI]

    Seo, Kwang Seok

    , such as current collapse (power slump), the self-heating effect and the power scaling problem. In this paper, we have studied the self-heating effect using pulsed current-voltage (IV) and current- voltage self-heating affects the AlGaN/GaN HEMT's operation. It can be thought that a reason for the power

  12. Self-Heating Effects in GaN/AlGaN Heterostructure Field-Effect Transistors and Device Structure Optimization

    E-Print Network [OSTI]

    Self-Heating Effects in GaN/AlGaN Heterostructure Field-Effect Transistors and Device Structure time, performance of these devices has been limited by self-heating and other problems associated-3]. At the same time, performance of these devices has been limited by self-heating and other problems associated

  13. Fabrication of quantum point contacts by engraving GaAsAlGaAs heterostructures with a diamond tip

    E-Print Network [OSTI]

    Hohls, Frank

    by hot-filament chemical vapor deposition of polycrystalline diamond onto a prepat- terned siliconFabrication of quantum point contacts by engraving GaAsÕAlGaAs heterostructures with a diamond tip for publication 17 July 2002 We use the all-diamond tip of an atomic force microscope for the direct engraving

  14. Reconstructions of GaN,,0001... and ,,0001... surfaces: Ga-rich metallic A. R. Smith and R. M. Feenstraa)

    E-Print Network [OSTI]

    wurtzite material.1­9 A common theme regarding the growth of these surfaces in the absence of hydrogen and elec- tronic properties of two reconstructions for wurtzite GaN: the 1 1 structure of the GaN 0001

  15. Electronic band-structure engineering of GaAs/AlxGa1(xAs quantum well superlattices with substructures

    E-Print Network [OSTI]

    Cao, Wenwu

    Electronic band-structure engineering of GaAs/AlxGa1(xAs quantum well superlattices investigation on the band structures of electrons in both infinite and finite semiconductor quantum well of these two materials, narrower passbands and/or broad stopbands can be obtained for electrons with energy

  16. OPTIMIZATION OF GaN WINDOW LAYER FOR InGaN SOLAR CELLS USING POLARIZATION EFFECT

    E-Print Network [OSTI]

    Honsberg, Christiana

    on the design of wide-band gap GaN window layers for InGaN solar cells. Window layers serve to passivate the top into account during design of the solar cell to improve its collection efficiency. Previously, we have. The present work is a subset of the design optimization process for such solar cells, where we focus

  17. Si-CMOS-Like Integration of AlGaN/GaN Dielectric-Gated High-Electron-Mobility Transistors

    E-Print Network [OSTI]

    Johnson, Derek Wade

    2014-07-31T23:59:59.000Z

    the engineering of high mobility, high carrier density channels at III-Nitride heterointerfaces. In order to seize market share from silicon, the cost of manufacturing GaN-based devices must be further reduced. With the successful realization of 200mm Ga...

  18. Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated Antenna Approach

    E-Print Network [OSTI]

    Itoh, Tatsuo

    Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated 1200, Los Angeles, CA 90045 Abstract -- In this paper, effects of output harmonic terminations on PAE termination, we observe a substantial increase in PAE and output power. Further, we demonstrate the high

  19. Diffusion of a Ga adatom on the GaAs(001)c(44)heterodimer surface: A first principles study

    E-Print Network [OSTI]

    Khare, Sanjay V.

    Diffusion of a Ga adatom on the GaAs(001)c(4×4)heterodimer surface: A first principles study J Diffusion barriers Reconstruction Density functional calculations The adsorption and diffusion behavior functional theory (DFT) computations in the local density approxima- tion. Structural and bonding features

  20. Electric field dependent radiative decay kinetics of polar InGaN/GaN quantum heterostructures at low fields

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    Electric field dependent radiative decay kinetics of polar InGaN/GaN quantum heterostructures with increasing external electric field, with the radiative component exhibiting weaker field dependence. © 2009 applied electric field in Ref. 12, the electric field dependent radiative recombination in particular has

  1. Wavelength dependence of the threshold in an InGaP-InAlGaP vertical cavity surface emitting laser

    SciTech Connect (OSTI)

    Chow, W.W.; Schneider, R.P. Jr.; Lott, J.A.; Choquette, K.D. (Sandia National Laboratories, Albuquerque, New Mexico 87185-0350 (United States))

    1994-07-11T23:59:59.000Z

    The wavelength dependence of the threshold in an InGaP-InAlGaP vertical cavity surface emitting laser is investigated using a microscopic theory of the semiconductor gain medium. Good agreement is found between experiment and theory for the minimum threshold lasing wavelength for a range of laser structures.

  2. Si-CMOS-Like Integration of AlGaN/GaN Dielectric-Gated High-Electron-Mobility Transistors 

    E-Print Network [OSTI]

    Johnson, Derek Wade

    2014-07-31T23:59:59.000Z

    the engineering of high mobility, high carrier density channels at III-Nitride heterointerfaces. In order to seize market share from silicon, the cost of manufacturing GaN-based devices must be further reduced. With the successful realization of 200mm Ga...

  3. Ga induced superstructures as templates for lattice matched hetroepitaxial growth of GaN on Si(111) substrate

    SciTech Connect (OSTI)

    Kumar, Praveen; Kuyyalil, Jithesh; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, 560 064 Bangalore (India)

    2010-11-29T23:59:59.000Z

    High quality GaN is grown by plasma assisted molecular beam epitaxy on Ga induced superstructural phases of Si(111)7x7. Three stable surface phases induced by Ga adsorption, viz., (1x1), (6.3x6.3), and ({radical}3x{radical}3)R30 deg., are employed as templates to grow epitaxial (0001) GaN thin films. GaN grown on Si({radical}3x{radical}3)R30 deg. -Ga is found to be highly crystalline with intense (0002) x-ray diffraction and photoluminescence peaks with low full width at half maximum, low surface roughness, and stoichiometric surface composition. The high quality of these GaN films formed at a low temperature of 400 deg. C is explained by the integral (x2) lattice matching between the unit cell of GaN and the ({radical}3x{radical}3) phase. The experiments demonstrate a plausible approach of adsorbate induced surface modifications as templates for III-V hetroepitaxy on Si surfaces.

  4. High Breakdown ( > \\hbox {1500 V} ) AlGaN/GaN HEMTs by Substrate-Transfer Technology

    E-Print Network [OSTI]

    Lu, Bin

    In this letter, we present a new technology to increase the breakdown voltage of AlGaN/GaN high-electron-mobility transistors (HEMTs) grown on Si substrates. This new technology is based on the removal of the original Si ...

  5. Sputtering of Si, SiC, InAs, InP, Ge, GaAs, GaSb, and GaN by electrosprayed nanodroplets

    SciTech Connect (OSTI)

    Borrajo-Pelaez, Rafael; Grustan-Gutierrez, Enric; Gamero-Castaño, Manuel, E-mail: mgameroc@uci.edu [Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92697 (United States)

    2013-11-14T23:59:59.000Z

    This article presents a characterization of the damage caused by energetic beams of electrosprayed nanodroplets striking the surfaces of single-crystal semiconductors including Si, SiC, InAs, InP, Ge, GaAs, GaSb, and GaN. The sputtering yield (number of atoms ejected per projectile's molecule), sputtering rate, and surface roughness are measured as functions of the beam acceleration potential. The maximum values of the sputtering yields range between 1.9 and 2.2 for the technological important but difficult to etch SiC and GaN respectively, and 4.5 for Ge. The maximum sputtering rates for the non-optimized beam flux conditions used in our experiments vary between 409?nm/min for SiC and 2381?nm/min for GaSb. The maximum sputtering rate for GaN is 630?nm/min. Surface roughness increases modestly with acceleration voltage, staying within 2?nm and 20?nm for all beamlet acceleration potentials and materials except Si. At intermediate acceleration potentials, the surface of Si is formed by craters orders of magnitude larger than the projectiles, yielding surface roughness in excess of 60?nm. The effect of projectile dose is studied in the case of Si. This parameter is correlated with the formation of the large craters typical of Si, which suggests that the accumulation of damage following consecutive impacts plays an important role in the interaction between beamlet and target.

  6. Strain relaxation effect by nanotexturing InGaN/GaN multiple quantum well

    SciTech Connect (OSTI)

    Ramesh, V.; Kikuchi, A.; Kishino, K. [Department of Electrical and Electronics Engineering, Sophia University, Tokyo 102-8554, Japan and Nano-technology Research Center, Sophia University, Tokyo 102-8554 (Japan); CREST, JST, Saitama 332-0012 (Japan); Funato, M.; Kawakami, Y. [CREST, JST, Saitama 332-0012 (Japan); Department of Electronics Science and Engineering, Kyoto University, Kyoto 615-8510 (Japan)

    2010-06-15T23:59:59.000Z

    The relaxation of lattice-mismatched strain by deep postetching was systematically investigated for InGaN/GaN multiple quantum wells (MQWs). A planar heterojunction wafer, which included an In{sub 0.21}Ga{sub 0.79}N (3.2 nm)/GaN (14.8 nm) MQW, was etched by inductively coupled plasma dry etching, to fabricate high-density nanopillar, nanostripe, and nanohole arrays. The etching depth was 570 nm for all nanostructures. The diameter of the nanopillars was varied from 50 to 300 nm, then the mesa stripe width of the nanostripes and the diameter of the nanoholes were varied from 100 nm to 440 nm and 50 nm to 310 nm, respectively. The effect of strain relaxation on various optical properties was investigated. For example, in an array of nanopillars with diameter 130 nm and interval 250 nm, a large blueshift in the photoluminescence (PL) emission peak from 510 nm (as-grown) to 459 nm occurred at room temperature (RT). PL internal quantum efficiency (defined by the ratio of PL integral intensity at 300 K to that at 4.2 K) was enhanced from 34% (as-grown) to 60%, and the PL decay time at 4.2 K was reduced from 22 ns (as-grown) to 4.2 ns. These results clearly indicate the reduction of lattice-mismatched strain by postetching, which enhanced strain reduction with decreasing nanopillar diameter down to a diameter of 130 nm, where the strain reduction became saturated. The dependence of RT-PL decay time on nanopillar diameter was measured, and the surface nonradiative recombination velocity was estimated to be 5.8x10{sup 2} cm/s. This relatively slow rate indicates a little etching damage.

  7. Infrared emission from the substrate of GaAs-based semiconductor lasers Mathias Ziegler,1,a

    E-Print Network [OSTI]

    Peinke, Joachim

    by metal- organic vapor phase epitaxy on a n-type GaAs substrate. The red-emitting laser employs an InGaP

  8. Partially filled intermediate band of Cr-doped GaN films

    SciTech Connect (OSTI)

    Sonoda, S. [Department of Electronics, Kyoto Institute of Technology, Kyoto 606-8585 (Japan)

    2012-05-14T23:59:59.000Z

    We investigated the band structure of sputtered Cr-doped GaN (GaCrN) films using optical absorption, photoelectron yield spectroscopy, and charge transport measurements. It was found that an additional energy band is formed in the intrinsic band gap of GaN upon Cr doping, and that charge carriers in the material move in the inserted band. Prototype solar cells showed enhanced short circuit current and open circuit voltage in the n-GaN/GaCrN/p-GaN structure compared to the GaCrN/p-GaN structure, which validates the proposed concept of an intermediate-band solar cell.

  9. Variables and units in Ocean 420 u zonal velocity (east-west) m/s

    E-Print Network [OSTI]

    Thompson, LuAnne

    speed m/s Cg group velocity m/s k wave number 1/m frequency 1/s wavelength m T period s kinematic mixed-layer and water below C E Energy density in surface gravity wave J/m 2 #12;Some constants k Von surface height m g gravitational constant m/s 2 a amplitude of wave in sea surface height m f Coriolis

  10. STEPS: A Grid Search Methodology for Optimized Peptide Identification Filtering of MS/MS Database Search Results

    SciTech Connect (OSTI)

    Piehowski, Paul D.; Petyuk, Vladislav A.; Sandoval, John D.; Burnum, Kristin E.; Kiebel, Gary R.; Monroe, Matthew E.; Anderson, Gordon A.; Camp, David G.; Smith, Richard D.

    2013-03-01T23:59:59.000Z

    For bottom-up proteomics there are a wide variety of database searching algorithms in use for matching peptide sequences to tandem MS spectra. Likewise, there are numerous strategies being employed to produce a confident list of peptide identifications from the different search algorithm outputs. Here we introduce a grid search approach for determining optimal database filtering criteria in shotgun proteomics data analyses that is easily adaptable to any search. Systematic Trial and Error Parameter Selection - referred to as STEPS - utilizes user-defined parameter ranges to test a wide array of parameter combinations to arrive at an optimal "parameter set" for data filtering, thus maximizing confident identifications. The benefits of this approach in terms of numbers of true positive identifications are demonstrated using datasets derived from immunoaffinity-depleted blood serum and a bacterial cell lysate, two common proteomics sample types.

  11. Field dependent emission rates in radiation damaged GaAs

    SciTech Connect (OSTI)

    Fleming, R. M.; Myers, S. M.; Wampler, W. R.; Lang, D. V.; Seager, C. H.; Campbell, J. M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1415 (United States)

    2014-07-07T23:59:59.000Z

    We have measured the temperature and field dependence of emission rates from five traps in electron damaged GaAs. Four of the traps have previously been identified as radiation defects. One of the traps, seen in higher doped diodes, has not been previously identified. We have fit the data to a multiphonon emission theory that allows recombination in GaAs to be characterized over a broad range of temperature and electric field. These results demonstrate an efficient method to calculate field-dependent emission rates in GaAs.

  12. Evidence of N substitution by Mn in GaN

    E-Print Network [OSTI]

    Pereira, LMC; Decoster, S; Correia, JG; da Silva, MR; Vantomme, A; Araújo, JP

    2012-01-01T23:59:59.000Z

    We report on the lattice location of Mn in wurtzite GaN using beta? emission channeling. In addition to the majority substituting for Ga, we locate up to 20% of the Mn atoms in N sites. We propose that the incorporation of Mn in N sites is enabled under sufficiently high concentrations of N vacancies, and stabilized by a highly charged state of the Mn cations. Since N substitution by Mn impurities in wurtzite GaN has never been observed experimentally or even considered theoretically before, it challenges the current paradigm of transition metal incorporation in wide-gap dilute magnetic semiconductors.

  13. Ferromagnetism in undoped One-dimensional GaN Nanowires

    SciTech Connect (OSTI)

    Jeganathan, K., E-mail: kjeganathan@yahoo.com, E-mail: jagan@physics.bdu.ac.in; Purushothaman, V. [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India)] [Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli - 620 024 (India); Debnath, R. [Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4 (Canada)] [Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario M5S 3G4 (Canada); Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli – 620 024 (India)] [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli – 620 024 (India)

    2014-05-15T23:59:59.000Z

    We report an intrinsic ferromagnetism in vertical aligned GaN nanowires (NW) fabricated by molecular beam epitaxy without any external catalyst. The magnetization saturates at ?0.75 × emu/gm with the applied field of 3000 Oe for the NWs grown under the low-Gallium flux of 2.4 × 10{sup ?8} mbar. Despite a drop in saturation magnetization, narrow hysteresis loop remains intact regardless of Gallium flux. Magnetization in vertical standing GaN NWs is consistent with the spectral analysis of low-temperature photoluminescence pertaining to Ga-vacancies associated structural defects at the nanoscale.

  14. Optical spectroscopy of cubic GaN in nanowires

    SciTech Connect (OSTI)

    Renard, J. [CEA-CNRS Group 'Nanophysique et semiconducteurs', CEA-Grenoble INAC-SP2M, Institut Neel, CNRS, Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z4 (Canada); Tourbot, G. [CEA-CNRS Group 'Nanophysique et semiconducteurs', CEA-Grenoble INAC-SP2M, Institut Neel, CNRS, Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France); CEA-LETI, MINATEC, 17 rue des Martyrs 38054 Grenoble Cedex 9 (France); Sam-Giao, D.; Bougerol, C.; Daudin, B.; Gayral, B. [CEA-CNRS Group 'Nanophysique et semiconducteurs', CEA-Grenoble INAC-SP2M, Institut Neel, CNRS, Universite Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble (France)

    2010-08-23T23:59:59.000Z

    We show that highly homogeneous cubic GaN can be grown by plasma-assisted molecular beam epitaxy on wurtzite GaN nanowires. The line width of the donor bound exciton is below 3 meV and can reach 1.6 meV in the best parts of the studied sample. This allows to perform a detailed spectroscopy of cubic GaN, and, in particular, to determine the precise spectral positions of the donor bound exciton, the fundamental free exciton and the split-off exciton in a photoluminescence experiment.

  15. Discovery of novel glucose-regulated proteins in isolated human pancreatic islets using LC-MS/MS-based proteomics

    SciTech Connect (OSTI)

    Rutledge, Alexandra C.; Fontes, Ghislaine; Gritsenko, Marina A.; Norbeck, Angela D.; Anderson, David J.; Waters, Katrina M.; Adkins, Joshua N.; Smith, Richard D.; Poitout, Vincent; Metz, Thomas O.

    2012-07-06T23:59:59.000Z

    The prevalence of diabetes mellitus is increasing dramatically throughout the world, and the disease has become a major public health issue. The most common form of the disease, type 2 diabetes, is due in part to insufficient insulin production from the pancreatic beta-cell. Since glucose is the most potent and physiologically important regulators of beta-cell function under physiological conditions, understanding the insulin secretory defect underlying type 2 diabetes requires a better understanding of glucose regulation of beta-cell function. To this aim, a bottom-up LC-MS/MS-based proteomics approach was used to profile pooled islets from multiple donors under basal (5 mM) or high (15 mM) glucose conditions. Our analysis discovered 256 differentially abundant proteins ({approx}p < 0.05) after 24 h of high glucose exposure from more than 4500 identified in total. Several novel glucose-regulated proteins were elevated under high glucose conditions, including regulators of mRNA splicing (Pleiotropic regulator 1), processing (Retinoblastoma binding protein 6), and function (Nuclear RNA export factor 1), in addition to Neuron navigator 1 and Plasminogen activator inhibitor 1. Proteins whose abundances markedly decreased during incubation at 15 mM glucose included Bax inhibitor 1 and Synaptotagmin-17. Many proteins found to be differentially abundant after high glucose stimulation were uncharacterized or hypothetical. These findings expand our knowledge of glucose regulation of the human islet proteome and suggest many hitherto unknown responses to glucose that require additional studies to explore novel functional roles.

  16. Application of Printed Circuit Board Technology to FT-ICR MS...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Technology to FT-ICR MS Analyzer Cell Construction and Prototyping. Abstract: Although Fourier transform ion cyclotron resonance mass spectrometry (FT-ICRMS) remains themass...

  17. Apply for the OIA Undergraduate Scholarship 1. Your name Mr. Miss, Ms., Mrs.

    E-Print Network [OSTI]

    Rock, Chris

    Apply for the OIA Undergraduate Scholarship 1. Your name Mr. Miss, Ms., Mrs. Family Name (as of birth (country): ____________________________________________ Page 1 of 3 You are eligible

  18. Electrical spin injection using GaCrN in a GaN based spin light emitting diode

    SciTech Connect (OSTI)

    Banerjee, D.; Ganguly, S.; Saha, D., E-mail: dipankarsaha@iitb.ac.in [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); IITB-Monash Research Academy, Indian Institute of Technology Bombay, Mumbai 400076 (India); Adari, R.; Sankaranarayan, S.; Kumar, A. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India)] [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076 (India); Aldhaheri, R. W.; Hussain, M. A.; Balamesh, A. S. [Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)] [Department of Electrical and Computer Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2013-12-09T23:59:59.000Z

    We have demonstrated electrical spin-injection from GaCrN dilute magnetic semiconductor (DMS) in a GaN-based spin light emitting diode (spin-LED). The remanent in-plane magnetization of the thin-film semiconducting ferromagnet has been used for introducing the spin polarized electrons into the non-magnetic InGaN quantum well. The output circular polarization obtained from the spin-LED closely follows the normalized in-plane magnetization curve of the DMS. A saturation circular polarization of ?2.5% is obtained at 200?K.

  19. Structural and optical properties of GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells

    SciTech Connect (OSTI)

    Aleshkin, V. Ya.; Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Drozdov, M. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Zvonkov, B. N. [Nizhni Novgorod State University, Research Physical Technical Institute (Russian Federation); Kudryavtsev, K. E.; Tonkikh, A. A.; Yablonskiy, A. N. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Werner, P. [Max Planck Institute of Microstructure Physics (Germany)

    2013-05-15T23:59:59.000Z

    GaAs-based heterostructures with Ge and Ge/InGaAs quantum wells are grown by laser-assisted sputtering. Structural and optical studies of the heterostructures are carried out. A broad photoluminescence line is observed in the wavelength range from 1300 to 1650 nm. The line corresponds to indirect transitions in the momentum space of the Ge quantum wells and to transitions between the In{sub 0.28}Ga{sub 0.72}As and Ge layers, indirect in coordinate space, but direct in momentum space.

  20. Microscopic, electrical and optical studies on InGaN/GaN quantum wells based LED devices

    SciTech Connect (OSTI)

    Mutta, Geeta Rani; Venturi, Giulia; Castaldini, Antonio; Cavallini, Anna [Department of Physics and Astronomy, University of Bologna, Viale Carlo Berti Pichat 6/II, 40127 Bologna (Italy); Meneghini, Matteo; Zanoni, Enrico; Meneghesso, Gaudenzio [University of Padova, Department of Information Engineering, via Gradenigo 6/B, Padova 35131 (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

    2014-02-21T23:59:59.000Z

    We report here on the micro structural, electronic and optical properties of a GaN-based InGaN/GaN MQW LED grown by the MOVPE method. The present study shows that the threading dislocations present in these LED structures are terminated as V pits at the surface and have an impact on the electrical and optical activity of these devices. It has been pointed that these dislocations were of edge, screw and mixed types. EBIC maps suggest that the electrically active defects are screw and mixed dislocations and behave as nonradiative recombinant centres.

  1. Waveguide effect of GaAsSb quantum wells in a laser structure based on GaAs

    SciTech Connect (OSTI)

    Aleshkin, V. Ya. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Afonenko, A. A. [Belarussian State University (Belarus)] [Belarussian State University (Belarus); Dikareva, N. V. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation); Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Kudryavtsev, K. E.; Morozov, S. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Nekorkin, S. M. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)

    2013-11-15T23:59:59.000Z

    The waveguide effect of GaAsSb quantum wells in a semiconductor-laser structure based on GaAs is studied theoretically and experimentally. It is shown that quantum wells themselves can be used as waveguide layers in the laser structure. As the excitation-power density attains a value of 2 kW/cm{sup 2} at liquid-nitrogen temperature, superluminescence at the wavelength corresponding to the optical transition in bulk GaAs (at 835 nm) is observed.

  2. High temperature stable W and WSi{sub x} ohmic contacts on GaN and InGaN

    SciTech Connect (OSTI)

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

    1996-06-01T23:59:59.000Z

    Conventional III-V metallizations chemes such as Au/Ge/Ni, Ti/Pt/Au, and Au/Be were found to display poor thermal stability on both GaN and InGaN, with extensive reaction and contact degradation at {le}500 C. By contrast, W was found to produce low contact resistance ({rho}{sub c}{similar_to}8x10{sup -5}{Omega}cm{sup 2}) to n-GaN. Ga outdiffusion to the surface of thin (500 A) W films was found after annealing at 1,100 C, but not at 1000 C. Interfacial abruptness increased by 300A after 1,100 C annealing. In the case of WSi{sub X} (X=0.45), Ga outdiffusion was absent even at 1,100 C, but again there was interfacial broadening and some phase changes in the WSi{sub X}. On In{sub 0.5}Ga{sub 0.5}N, a minimum specific contact resistivity of 1.5 x10{sup -5}{Omega}cm{sup 2} was obtained for WSi{sub X} annealed at 700 C. These contacts retained a smooth morphology and abrupt interfaces to 800 C. Graded In{sub X}Ga{sub 1-X}N layers have been employed on GaAs/AlGaAs HBTs (heterojunction bipolar transistors), replacing conventional In{sub X}Ga{sub 1-X}As layers. R{sub C} values of 5x10{sup -7}{Omega}cm{sup 2} were obtained for nonalloyed Ti/Pt/Au on the InGaN, and the morphologies were superior to those of InGaAs contact layers. This proves to have significant advantages for fabrication of sub-micron HBTs. Devices with emitter dimensions of 2x5{mu}m{sup 2} displayed gains of 35 for a base doping level of 7x10{sup 19}cm{sup -3} and stable long-term behavior.

  3. Analytical modeling of AlGaN/AlN/GaN heterostructures including effects of distributed surface donor states

    SciTech Connect (OSTI)

    Goyal, Nitin, E-mail: nitin@unik.no [Carinthian Tech Research CTR AG, Europastraße 4/1, Technologiepark Villach, A-9524 Villach/St. Magdalen (Austria); Department of Electronics and Telecommunication, Norwegian University of Science and Technology, Trondheim NO7034 (Norway); Fjeldly, Tor A. [Department of Electronics and Telecommunication, Norwegian University of Science and Technology, Trondheim NO7034 (Norway)

    2014-07-14T23:59:59.000Z

    In this paper, a physics based analytical model is presented for calculation of the two-dimensional electron gas density and the bare surface barrier height of AlGaN/AlN/GaN material stacks. The presented model is based on the concept of distributed surface donor states and the self-consistent solution of Poisson equation at the different material interfaces. The model shows good agreement with the reported experimental data and can be used for the design and characterization of advanced GaN devices for power and radio frequency applications.

  4. Characterization of AlGaN/GaN Heterostructure Field Effect Transistors (HFETs) with Variable Thickness Channel and Substrate Type

    SciTech Connect (OSTI)

    Hussein, A. SH.; Hassan, Z.; Hassan, H. Abu; Thahab, S. M. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2010-07-07T23:59:59.000Z

    In this study, AlGaN/GaN-based heterostructure field effect transistor (HFET) was simulated by using ISE TCAD software. The effects of varying thickness, substrate type and doping channel levels were investigated. The device output characteristics of drain current and voltage with various gate biases were presented. A maximum drain current and extrinsic transconductance were achieved with AlGaN HFET grown on AlN/SiC substrate. The device performance can be improved by optimizing the substrate type and heavily doped channel layer which will reduce the contact resistance and enhance the transconductance. All results are comparable with the experimental results obtained by other researchers.

  5. Prospective emission efficiency and in-plane light polarization of nonpolar m-plane InxGa1-xN/GaN blue light emitting diodes fabricated on freestanding GaN substrates

    E-Print Network [OSTI]

    2006-01-01T23:59:59.000Z

    m-plane In x Ga 1?x N / GaN blue light emitting diodesmea- surements. Since the blue MQW emission is polarized toS. Nakamura and G. Fasol, The Blue Laser Diode ?Springer,

  6. Transverse acoustic actuation of Ni-Mn-Ga single crystals

    E-Print Network [OSTI]

    Simon, Jesse Matthew

    2007-01-01T23:59:59.000Z

    Two methods for the transverse acoustic actuation of {110}-cut Ni-Mn-Ga single crystals are discussed. In this actuation mode, crystals are used that have the {110}- type twinning planes parallel to the base of the crystal. ...

  7. Beta-decay branching ratios of 62Ga

    E-Print Network [OSTI]

    A. Bey; B. Blank; G. Canchel; C. Dossat; J. Giovinazzo; I. Matea; V. Elomaa; T. Eronen; U. Hager; M. Hakala; A. Jokinen; A. Kankainen; I. Moore; H. Penttila; S. Rinta-Antila; A. Saastamoinen; T. Sonoda; J. Aysto; N. Adimi; G. De France; J. C. Thomas; G. Voltolini; T. Chaventré

    2008-04-17T23:59:59.000Z

    Beta-decay branching ratios of 62Ga have been measured at the IGISOL facility of the Accelerator Laboratory of the University of Jyvaskyla. 62Ga is one of the heavier Tz = 0, 0+ -> 0+ beta-emitting nuclides used to determine the vector coupling constant of the weak interaction and the Vud quark-mixing matrix element. For part of the experimental studies presented here, the JYFLTRAP facility has been employed to prepare isotopically pure beams of 62Ga. The branching ratio obtained, BR= 99.893(24)%, for the super-allowed branch is in agreement with previous measurements and allows to determine the ft value and the universal Ft value for the super-allowed beta decay of 62Ga.

  8. GaBo{sub 3} crystal growth from flux

    SciTech Connect (OSTI)

    Rudenko, V.V. [Institute of Physics, Krasnoyarsk (Russian Federation)

    1995-03-01T23:59:59.000Z

    Synthesis of the chemical compound GaBO{sub 3} was first reported in paper, and the crystallographic determination of its structure and unit cell parameters was presented in paper. The chemical compound GaBO{sub 3} crystallizes in a calcite structure type with the hexagonal unit cell Parameters a{sub H} = 4.568 and c{sub H} = 14.18 {Angstrom}. GaBO{sub 3} crystals in the form of (111) hexagonal plates were grown from the solvent B{sub 2}O{sub 3}-Bi{sub 2}O{sub 3} by the method of sponvineous crystallization. That technique was hard to reproduce, however. We decided to grow a GaBO{sub 3} crystal as an object for possible studies of various physical properties. 8 refs., 2 figs.

  9. Evaporation-based Ge/.sup.68 Ga Separation

    DOE Patents [OSTI]

    Mirzadeh, Saed (Albuquerque, NM); Whipple, Richard E. (Los Alamos, NM); Grant, Patrick M. (Los Alamos, NM); O'Brien, Jr., Harold A. (Los Alamos, NM)

    1981-01-01T23:59:59.000Z

    Micro concentrations of .sup.68 Ga in secular equilibrium with .sup.68 Ge in strong aqueous HCl solution may readily be separated in ionic form from the .sup.68 Ge for biomedical use by evaporating the solution to dryness and then leaching the .sup.68 Ga from the container walls with dilute aqueous solutions of HCl or NaCl. The chloro-germanide produced during the evaporation may be quantitatively recovered to be used again as a source of .sup.68 Ga. If the solution is distilled to remove any oxidizing agents which may be present as impurities, the separation factor may easily exceed 10.sup.5. The separation is easily completed and the .sup.68 Ga made available in ionic form in 30 minutes or less.

  10. Electrical degradation mechanisms of RF power GaAs PHEMTs

    E-Print Network [OSTI]

    Villanueva, Anita A. (Anita Ariel), 1978-

    2007-01-01T23:59:59.000Z

    GaAs Pseudomorphic High-Electron Mobility Transistors (PHEMTs) are widely used in RF power applications. Since these devices typically operate at high power levels and under high voltage biasing, their electrical reliability ...

  11. Quantitative analysis of compositional changes in InGaAs/InGaAsP quantum wells on GaAs induced by intermixing with a low temperature grown InGaP cap layer

    SciTech Connect (OSTI)

    Hulko, O.; Thompson, D. A.; Czaban, J. A.; Simmons, J. G. [Centre for Emerging Devices and Technologies (CEDT), McMaster University, Hamilton, Ontario L8S 4L8 (Canada)

    2006-08-07T23:59:59.000Z

    Energy-dispersive x-ray spectroscopy was used to analyze quantum well intermixing between an InGaAs quantum well (QW) and InGaAsP barriers grown on GaAs induced by a low temperature, molecular beam epitaxy grown, InGaP cap. This cap layer produces an enhanced blueshift of the photoluminescence (PL) wavelength following postgrowth annealing, and degradation of the PL signal. Cross-sectional transmission electron microscopy reveals modification of the whole structure, with formation of arsenic precipitates, broadening, and subsequent disappearance of the QWs in the capped structure. Uncapped samples are relatively unchanged. Increased phosphorus observed in the QW for capped structures confirms the diffusion of phosphorus from the P-rich cap.

  12. Sandia National Laboratories: GaN-based nanowire laser

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    GaN-based nanowire laser BES Web Highlight: Single-mode gallium nitride nanowire lasers On January 28, 2013, in EC, Energy Efficiency, Solid-State Lighting A new top-down method...

  13. Micro Raman Spectroscopy of Annealed Erbium Implanted GaN

    E-Print Network [OSTI]

    Vajpeyi, Agam P.

    Wurtzite GaN epilayers grown by metal organic chemical vapor deposition on sapphire substrates were subsequently ion implanted with Er to a dose of 5×10¹? cm?². The implanted samples were annealed in nitrogen atmosphere ...

  14. AlGaAs/GaAs quantum well infrared detectors and modulators

    E-Print Network [OSTI]

    Dave, Digant Praful

    1990-01-01T23:59:59.000Z

    of boundary condition (1) we find that F=D=O Applying the boundary conditions (2) and (3) to the Schrodinger equation we get four ordinary equations. at x=-a -Asin(qa) + Bcos(qa) = Ce-" qAcos(qa) + qBsin(qa) = sCe ~ (4 7) (4 6) atx= a Asin... been extensively used for quantum well applications and studies is because of the excellent lattice match that exists between GaAs and AIAs. This feature is quite clear from the Fig. 2. They have less than 0. 13/o of lattice mismatch. The lattice...

  15. Characteristics of Novel InGaAsN Double Heterojunction Bipolar Transistors

    SciTech Connect (OSTI)

    LI,N.Y.; CHANG,PING-CHIH; BACA,ALBERT G.; LAROCHE,J.R.; REN,F.; ARMOUR,E.; SHARPS,P.R.; HOU,H.Q.

    2000-08-01T23:59:59.000Z

    The authors demonstrate, for the first time, both functional Pnp AlGaAs/InGaAsN/GaAs (Pnp InGaAsN) and Npn InGaP/InGaAsN/GaAs (Npn InGaAsN) double heterojunction bipolar transistors (DHBTs) using a 1.2 eV In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} as the base layer for low-power electronic applications. The Pnp InGaAsN DHBT has a peak current gain ({beta}) of 25 and a low turn-on voltage (V{sub ON}) of 0.79 V. This low V{sub ON} is {approximately} 0.25 V lower than in a comparable Pnp AlGAAs/GaAs HBT. For the Npn InGaAsN DHBT, it has a low V{sub ON} of 0.81 V, which is 0.13 V lower than in an InGaP/GaAs HBT. A peak {beta} of 7 with nearly ideal I-V characteristics has been demonstrated. Since GaAs is used as the collector of both Npn and Pnp InGaAsN DHBTs, the emitter-collector breakdown voltage (BV{sub CEO}) are 10 and 12 V, respectively, consistent with the BV{sub CEO} of Npn InGaP/GaAs and Pnp AlGaAs/GaAs HBTs of comparable collector thickness and doping level. All these results demonstrate the potential of InGaAsN DHBTs as an alternative for application in low-power electronics.

  16. Effect of Sb on the Properties of GaInP Top Cells (Presentation)

    SciTech Connect (OSTI)

    Olson, J. M.; McMahon, W. E.; Kurtz, S.

    2006-05-01T23:59:59.000Z

    The summary of this report is that: (1) Sb can be used to increase V{sub oc} of a GaInP top cell; (2) the photovoltaic quality of GaInP is relatively unaffected by the presence of Sb; and (3) Sb-doped GaInP/GaAs tandem cells show promise for achieving efficiencies over 32%.

  17. Wurtzite GaN Surface Structures Studied by Scanning Tunneling Microscopy and Reflection High Energy

    E-Print Network [OSTI]

    Feenstra, Randall

    Wurtzite GaN Surface Structures Studied by Scanning Tunneling Microscopy and Reflection High Energy studies of the surface reconstructions for both the Ga-face and the N-face of wurtzite GaN films grown a surface phenomenon. Although numerous surface studies of wurtzite GaN have been performed, progress

  18. MBE growth and applications of cubic AlN/GaN quantum wells

    E-Print Network [OSTI]

    As, Donat Josef

    MBE growth and applications of cubic AlN/GaN quantum wells Donat J. As* and Christian Mietze Keywords cubic AlN, GaN, interband and intersubband transitions, MBE, resonant tunneling * Corresponding regions. In this contribution, the latest achievement in the MBE of phase-pure cubic GaN, AlN, and AlN/GaN

  19. Behavior of aluminum adsorption and incorporation at GaN(0001) surface: First-principles study

    SciTech Connect (OSTI)

    Qin, Zhenzhen; Xiong, Zhihua, E-mail: xiong-zhihua@126.com; Wan, Qixin [Key Laboratory for Optoelectronics and Communication of Jiangxi Province, Jiangxi Science and Technology Normal University, Nanchang 330018 (China); Qin, Guangzhao [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, University of Chinese Academy of Sciences, Beijing 101408 (China)

    2013-11-21T23:59:59.000Z

    First-principles calculations are performed to study the energetics and atomic structures of aluminum adsorption and incorporation at clean and Ga-bilayer GaN(0001) surfaces. We find the favorable adsorption site changes from T4 to T1 as Al coverage increased to 1 monolayer on the clean GaN(0001) surface, and a two-dimensional hexagonal structure of Al overlayer appears. It is interesting the Al atoms both prefer to concentrate in one deeper Ga layer of clean and Ga-bilayer GaN(0001) surface, respectively, while different structures could be achieved in above surfaces. For the case of clean GaN(0001) surface, corresponding to N-rich and moderately Ga-rich conditions, a highly regular superlattice structure composed of wurtzite GaN and AlN becomes favorable. For the case of Ga-bilayer GaN(0001) surface, corresponding to extremely Ga-rich conditions, the Ga bilayer is found to be sustained stable in Al incorporating process, leading to an incommensurate structure directly. Furthermore, our calculations provide an explanation for the spontaneous formation of ordered structure and incommensurate structure observed in growing AlGaN films. The calculated results are attractive for further development of growth techniques and excellent AlGaN/GaN heterostructure electronic devices.

  20. Large atomic displacements associated with the nitrogen antisite in GaN T. Mattila*

    E-Print Network [OSTI]

    Large atomic displacements associated with the nitrogen antisite in GaN T. Mattila* Laboratory of an extensive theoretical study of the nitrogen antisite in GaN. The neutral antisite in c-GaN is reported the nitrogen antisite and the yellow luminescence commonly observed in GaN is discussed. S0163-1829 96 05824

  1. Vertical design of cubic GaN-based high electron mobility transistors R. Granzner,1,a)

    E-Print Network [OSTI]

    As, Donat Josef

    Vertical design of cubic GaN-based high electron mobility transistors R. Granzner,1,a) E. Tschumak 2011; accepted 24 October 2011; published online 1 December 2011) Cubic (zinc blende) AlGaN=GaN heterostructures for application in GaN-based high electron mobility transistors are investigated theoretically

  2. Watching GaN Nanowires Grow Eric A. Stach,*, Peter J. Pauzauskie, Tevye Kuykendall,

    E-Print Network [OSTI]

    Yang, Peidong

    Watching GaN Nanowires Grow Eric A. Stach,*, Peter J. Pauzauskie, Tevye Kuykendall, Joshua of the growth of GaN nanowires via a self-catalytic vapor-liquid-solid (VLS) mechanism. High temperature thermal decomposition of GaN in a vacuum yields nanoscale Ga liquid droplets and gallium/nitrogen vapor species

  3. In situ growth regime characterization of cubic GaN using reflection high energy electron diffraction

    E-Print Network [OSTI]

    As, Donat Josef

    from Knudsen cells. Cubic GaN layers were deposited at 720 °C directly on 3C-SiC substrates shutters the GaN surface was exposed to different Ga fluxes for a certain time. The substrate temperatureIn situ growth regime characterization of cubic GaN using reflection high energy electron

  4. Strain dependent facet stabilization in selective-area heteroepitaxial growth of GaN nanostructures

    E-Print Network [OSTI]

    Sharma, Pradeep

    of submicron GaN islands on GaN-sapphire, AlN-sapphire, and bare sapphire substrates. It is shown that strain due to the lattice mismatch between GaN and the underlying substrate has a significant influence- structures has received less attention. Heteroepitaxial growth of GaN is commonly carried out on substrates

  5. Quadrupole mass spectrometry desorption analysis of Ga adsorbate on AIN (0001)

    E-Print Network [OSTI]

    Brown, J S; Koblmuller, G; Averbeck, R; Riechert, H; Speck, J S

    2006-01-01T23:59:59.000Z

    substrate temperatures similar to those used during PA-MBE growth of GaN /substrate temperature of 668– 669 ° C pre- dicted by the Ga/ GaNon GaN ?0001?. 13 At the 672± 2 ° C substrate temperature in

  6. Vertical strain and doping gradients in thick GaN layers H. Siegle,a)

    E-Print Network [OSTI]

    Nabben, Reinhard

    between layer and common substrates, e.g., sapphire or GaAs.1 Consequently, most GaN layers and also from the surface of the GaN layer nearer to the substrate interface, as can be seen from the CLVertical strain and doping gradients in thick GaN layers H. Siegle,a) A. Hoffmann, L. Eckey, and C

  7. Structural and electronic properties of Fe3+ in GaN from optical and EPR experiments

    E-Print Network [OSTI]

    Nabben, Reinhard

    into GaN to compensate inherent n-type conductivity and to produce semi-insulating substrate materialStructural and electronic properties of Fe3+ and Fe2+ centers in GaN from optical and EPR, and electronic properties of Fe-doped GaN. A set of high-quality GaN crystals doped with Fe at concentrations

  8. Terahertz plasma wave resonance of two-dimensional electrons in InGaP/InGaAs/GaAs high-electron-mobility transistors

    SciTech Connect (OSTI)

    Otsuji, Taiichi; Hanabe, Mitsuhiro; Ogawara, Osamu [Kyushu Institute of Technology, Graduate School of Computer Science and Systems Engineering, 680-4 Kawazu, Iizuka, Fukuoka, 820-8502 (Japan)

    2004-09-13T23:59:59.000Z

    We have observed the frequency dependence of the plasma resonant intensity in the terahertz range for a short gate-length InGaP/InGaAs/GaAs pseudomorphic high-electron-mobility transistor. The plasma resonance excitation was performed by means of interband photoexcitation using the difference-frequency component of a photomixed laser beam. Under sufficient density of two-dimensional (2D) conduction electrons (>10{sup 12} cm{sup -2}) and a moderate modulation index (the ratio of the density of photoexcited electrons to the initial density of the 2D electrons) we clearly observed the plasma-resonant peaks at 1.9 and 5.8 THz corresponding to the fundamental and third-harmonic resonance at room temperature, which is in good agreement with theory.

  9. A one-dimensional Fickian model to predict the Ga depth profiles in three-stage Cu(In,Ga)Se{sub 2}

    SciTech Connect (OSTI)

    Rodriguez-Alvarez, H., E-mail: humberto.rodriguez@helmholtz-berlin.de [International Iberian Nanotechnology Laboratory, Avenida Mestre Jose Veiga s/n, 4715-330 Braga (Portugal); Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Mainz, R. [Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Sadewasser, S. [International Iberian Nanotechnology Laboratory, Avenida Mestre Jose Veiga s/n, 4715-330 Braga (Portugal)

    2014-05-28T23:59:59.000Z

    We present a one-dimensional Fickian model that predicts the formation of a double Ga gradient during the fabrication of Cu(In,Ga)Se{sub 2} thin films by three-stage thermal co-evaporation. The model is based on chemical reaction equations, structural data, and effective Ga diffusivities. In the model, the Cu(In,Ga)Se{sub 2} surface is depleted from Ga during the deposition of Cu-Se in the second deposition stage, leading to an accumulation of Ga near the back contact. During the third deposition stage, where In-Ga-Se is deposited at the surface, the atomic fluxes within the growing layer are inverted. This results in the formation of a double Ga gradient within the Cu(In,Ga)Se{sub 2} layer and reproduces experimentally observed Ga distributions. The final shape of the Ga depth profile strongly depends on the temperatures, times and deposition rates used. The model is used to evaluate possible paths to flatten the marked Ga depth profile that is obtained when depositing at low substrate temperatures. We conclude that inserting Ga during the second deposition stage is an effective way to achieve this.

  10. Regrowth of diluted magnetic semiconductor GaMnAs on InGaP (001) surfaces to realize freestanding micromechanical structures

    SciTech Connect (OSTI)

    Choi, Hyung Kook; Lee, Joon Sue; Cho, Sung Woon; Lee, Won Oh; Shim, Seung Bo; Park, Yun Daniel [CSCMR and FPRD Department of Physics and Astronomy, Seoul National University, NS 50, Seoul 151- 747 (Korea, Republic of)

    2007-03-15T23:59:59.000Z

    Low temperature molecular beam epitaxy regrowths of Ga{sub 1-x}Mn{sub x}As (x{approx_equal}0.04) diluted magnetic semiconductors on GaAs/In{sub 1-y}Ga{sub y}P/GaAs(001) and In{sub 1-y}Ga{sub y}P/GaAs(001) (y{approx_equal}0.51) heterostructures prepared by metal-organic chemical vapor deposition are described. The resulting Ga{sub 1-x}Mn{sub x}As properties are comparable to epitaxial films grown directly on GaAs (001) substrates from in situ reflection high-energy electron diffraction, x-ray diffraction, magnetometry, and transport measurements with magnetic ordering temperature of as-grown films to range between {approx}50 and {approx}60 K. Postgrowth low temperature annealing enhances both magnetic and transport properties. Perfect etch selectivity between Ga{sub 1-x}Mn{sub x}As/GaAs and In{sub 1-y}Ga{sub y}P is utilized to realize suspended Ga{sub 1-x}Mn{sub x}As/GaAs doubly clamped beam micromechanical freestanding structures.

  11. Anti-phase domains in cubic GaN

    SciTech Connect (OSTI)

    Maria Kemper, Ricarda; Schupp, Thorsten; Haeberlen, Maik; Lindner, Joerg; Josef As, Donat [University of Paderborn, Department of Physics, Warburger Str. 100, D-33098 Paderborn (Germany); Niendorf, Thomas; Maier, Hans-Juergen [University of Paderborn, Lehrstuhl fuer Werkstoffkunde, Pohlweg 47-49, D-33098 Paderborn (Germany); Dempewolf, Anja; Bertram, Frank; Christen, Juergen [University of Magdeburg, Institut fuer Festkoerperphysik, P.O. Box 4120, D-39016 Magdeburg (Germany); Kirste, Ronny; Hoffmann, Axel [Technische Universitaet Berlin, Institute of Solid State Physics, Hardenbergstr. 36, D-10623 Berlin (Germany)

    2011-12-15T23:59:59.000Z

    The existence of anti-phase domains in cubic GaN grown on 3C-SiC/Si (001) substrates by plasma-assisted molecular beam epitaxy is reported. The influence of the 3C-SiC/Si (001) substrate morphology is studied with emphasis on the anti-phase domains (APDs). The GaN nucleation is governed by the APDs of the substrate, resulting in equal plane orientation and the same anti-phase boundaries. The presence of the APDs is independent of the GaN layer thickness. Atomic force microscopy surface analysis indicates lateral growth anisotropy of GaN facets in dependence of the APD orientation. This anisotropy can be linked to Ga and N face types of the {l_brace}111{r_brace} planes, similar to observations of anisotropic growth in 3C-SiC. In contrast to 3C-SiC, however, a difference in GaN phase composition for the two types of APDs can be measured by electron backscatter diffraction, {mu}-Raman and cathodoluminescence spectroscopy.

  12. Green (In,Ga,Al)P-GaP light-emitting diodes grown on high-index GaAs surfaces

    SciTech Connect (OSTI)

    Ledentsov, N. N., E-mail: nikolay.ledentsov@v-i-systems.com; Shchukin, V. A. [VI Systems GmbH, Hardenbergstr. 7, Berlin D-10623 (Germany); Lyytikäinen, J.; Okhotnikov, O. [Optoelectronics Research Centre, Tampere University of Technology, Tampere FI-33720 (Finland); Shernyakov, Yu. M.; Payusov, A. S.; Gordeev, N. Yu.; Maximov, M. V. [A. F. Ioffe Physical Technical Institute of the Russian Academy of Sciences, Politekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Schlichting, S.; Nippert, F.; Hoffmann, A. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin D-10623 (Germany)

    2014-11-03T23:59:59.000Z

    We report on green (550–560?nm) electroluminescence (EL) from (Al{sub 0.5}Ga{sub 0.5}){sub 0.5}In{sub 0.5}P-(Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P double p-i-n heterostructures with monolayer-scale GaP insertions in the cladding layers and light-emitting diodes based thereupon. The structures are grown side-by-side on high-index and (100) GaAs substrates by molecular beam epitaxy. At moderate current densities (?500?A/cm{sup 2}), the EL intensity of the structures is comparable for all substrate orientations. Opposite to the (100)-grown strictures, the EL spectra of (211) and (311)-grown devices are shifted towards shorter wavelengths (?550?nm at room temperature). At high current densities (>1?kA/cm{sup 2}), a much higher EL intensity is achieved for the devices grown on high-index substrates. The integrated intensity of (311)-grown structures gradually saturates at current densities above 4?kA/cm{sup 2}, whereas no saturation is revealed for (211)-grown structures up to the current densities above 14?kA/cm{sup 2}. We attribute the effect to the surface orientation-dependent engineering of the GaP band structure, which prevents the escape of the nonequilibrium electrons into the indirect conduction band minima of the p-doped (Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P cladding layers.

  13. High intensity low temperature (HILT) performance of space concentrator GaInP/GaInAs/Ge MJ SCs

    SciTech Connect (OSTI)

    Shvarts, Maxim Z., E-mail: shvarts@scell.ioffe.ru; Kalyuzhnyy, Nikolay A.; Mintairov, Sergey A.; Soluyanov, Andrei A.; Timoshina, Nailya Kh. [Ioffe Physical-Technical Institute, 26 Polytekhnicheskaya str., St.-Petersburg, 194021 (Russian Federation); Gudovskikh, Alexander S. [Saint-Petersburg Academic University - Nanotechnology Research and Education Centre RAS, St. Petersburg, 194021 (Russian Federation); Luque, Antonio [Ioffe Physical-Technical Institute, 26 Polytekhnicheskaya str., St.-Petersburg, 194021, Russia and Instituto de Energia Solar, Universidad Politecnica de Madrid, Madrid (Spain)

    2014-09-26T23:59:59.000Z

    In the work, the results of an investigation of GaInP/GaInAs/Ge MJ SCs intended for converting concentrated solar radiation, when operating at low temperatures (down to ?190 °C) are presented. A kink of the cell I-V characteristic has been observed in the region close to V{sub oc} starting from ?20°C at operation under concentrated sunlight. The causes for its occurrence have been analyzed and the reasons for formation of a built-in potential barrier for majority charge carriers at the n-GaInP/n-Ge isotype hetero-interface are discussed. The effect of charge carrier transport in n-GaInP/n-pGe heterostructures on MJ SC output characteristics at low temperatures has been studied including EL technique.

  14. Polarization field engineering of GaN/AlN/AlGaN superlattices for enhanced thermoelectric properties

    SciTech Connect (OSTI)

    Sztein, Alexander, E-mail: asztein@umail.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106 (United States); Bowers, John E.; DenBaars, Steven P.; Nakamura, Shuji [Materials Department, University of California, Santa Barbara, California 93106 (United States); Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

    2014-01-27T23:59:59.000Z

    A novel polarization field engineering based strategy to simultaneously achieve high electrical conductivity and low thermal conductivity in thermoelectric materials is demonstrated. Polarization based electric fields are used to confine electrons into two-dimensional electron gases in GaN/AlN/Al{sub 0.2}Ga{sub 0.8}N superlattices, resulting in improved electron mobilities as high as 1176 cm{sup 2}/Vs and in-plane thermal conductivity as low as 8.9?W/mK. The resulting room temperature ZT values reach 0.08, a factor of four higher than InGaN and twelve higher than GaN, demonstrating the potential benefits of this polarization based engineering strategy for improving the ZT and efficiencies of thermoelectric materials.

  15. Reducing the efficiency droop by lateral carrier confinement in InGaN/GaN quantum-well nanorods

    E-Print Network [OSTI]

    Shi, Chentian; Yang, Fan; Park, Min Joo; Kwak, Joon Seop; Jung, Sukkoo; Choi, Yoon-Ho; Wang, Xiaoyong; Xiao, Min

    2013-01-01T23:59:59.000Z

    Efficiency droop is a major obstacle facing high-power application of InGaN/GaN quantum-well (QW) light-emitting diodes. In this letter, we report the suppression of efficiency droop induced by density-activated defect recombination in nanorod structure of a-plane InGaN/GaN QWs. In the high carrier density regime, the retained emission efficiency in a dry-etched nanorod sample is observed to be over two times higher than that in its parent QW sample. We further argue that the improvement is a combined effect of the amendment contributed by lateral carrier confinement and the deterioration made by surface trapping.

  16. A new InGaP/GaAs tunneling heterostructure-emitter bipolar transistor (T-HEBT)

    SciTech Connect (OSTI)

    Tsai, Jung-Hui, E-mail: jhtsai@nknucc.nknu.edu.tw [National Kaohsiung Normal University, Department of Electronic Engineering, Taiwan (China); Lee, Ching-Sung [Feng Chia University, Department of Electronic Engineering, Taiwan (China); Lour, Wen-Shiung [National Taiwan Ocean University, Department of Electrical Engineering, Taiwan (China); Ma, Yung-Chun; Ye, Sheng-Shiun [National Kaohsiung Normal University, Department of Electronic Engineering, Taiwan (China)

    2011-05-15T23:59:59.000Z

    Excellent characteristics of an InGaP/GaAs tunneling heterostructure-emitter bipolar transistor (T-HEBT) are first demonstrated. The insertion of a thin n-GaAs emitter layer between tynneling confinement and base layers effectivelty eliminates the potential spike at base-emitter junction and reduces the collector-emitter offset voltage, while the thin InGaP tunneling confinement layer is employed to reduce the transporting time across emitter region for electrons and maintain the good confinement effect for holes. Experimentally, the studied T-HEBN exhibits a maximum current gain of 285, a relatively low offset voltage of 40 mW, and a current-gain cutoff frequency of 26.4 GHz.

  17. Reduced thermal resistance in AlGaN/GaN multi-mesa-channel high electron mobility transistors

    SciTech Connect (OSTI)

    Asubar, Joel T., E-mail: joel@rciqe.hokudai.ac.jp; Yatabe, Zenji; Hashizume, Tamotsu [Research Center for Integrated Quantum Electronics (RCIQE) and Graduate School of Information Science and Technology, Hokkaido University, Sapporo (Japan); Japan Science and Technology Agency (JST), CREST, 102-0075 Tokyo (Japan)

    2014-08-04T23:59:59.000Z

    Dramatic reduction of thermal resistance was achieved in AlGaN/GaN Multi-Mesa-Channel (MMC) high electron mobility transistors (HEMTs) on sapphire substrates. Compared with the conventional planar device, the MMC HEMT exhibits much less negative slope of the I{sub D}-V{sub DS} curves at high V{sub DS} regime, indicating less self-heating. Using a method proposed by Menozzi and co-workers, we obtained a thermal resistance of 4.8?K-mm/W at ambient temperature of ?350?K and power dissipation of ?9?W/mm. This value compares well to 4.1?K-mm/W, which is the thermal resistance of AlGaN/GaN HEMTs on expensive single crystal diamond substrates and the lowest reported value in literature.

  18. Epitaxial growth of Cu,,In,Ga...Se2 on GaAs,,110... and A. Rockett

    E-Print Network [OSTI]

    Rockett, Angus

    . INTRODUCTION The Cu(In, Ga)Se2 CIGS absorber layer in a recent record-efficiency CIGS solar cell1 has a 220.13 Commercially supplied ``epi-ready'' liquid- encapsulated Czo

  19. Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk

    SciTech Connect (OSTI)

    Zhuang, Y. D.; Shields, P. A.; Allsopp, D. W. E., E-mail: d.allsopp@bath.ac.uk [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom); Bruckbauer, J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom)

    2014-11-07T23:59:59.000Z

    Cathodoluminescence (CL) hyperspectral imaging has been performed on GaN nanorods containing a single InGaN quantum disk (SQD) with controlled variations in excitation conditions. Two different nanorod diameters (200 and 280?nm) have been considered. Systematic changes in the CL spectra from the SQD were observed as the accelerating voltage of the electron beam and its position of incidence are varied. It is shown that the dominant optical transition in the SQD varies across the nanorod as a result of interplay between the contributions of the deformation potential and the quantum-confined Stark effect to the transition energy as consequence of radial variation in the pseudomorphic strain.

  20. 1 AVS 2001 National Symposium, MS-TuA9 Research supported by

    E-Print Network [OSTI]

    Rubloff, Gary W.

    1 AVS 2001 National Symposium, MS-TuA9 Research supported by In-Situ FTIR Spectroscopy of Maryland, College Park, MD C.A. Gogol, J.F. Kushneir Inficon, Inc. East Syracuse, NY #12;2 AVS 2001 Spectroscopy Acoustic Sensing Ultra-Violet Spectroscopy #12;3 AVS 2001 National Symposium, MS-TuA9 Non

  1. REVISED 01/6/10 -MS SSRL/LCLS User Account Form

    E-Print Network [OSTI]

    Wechsler, Risa H.

    REVISED 01/6/10 - MS SSRL/LCLS User Account Form To open or renew an account, complete and submit Park, CA 94025 FAX: 650-926-8665 TEL: 650-926-3011 SSRL/LCLS SPOKESPERSON): __________________________ _________________________ __________________________ _________________________ __________________________ _________________________ __________________________ _________________________ __________________________ _________________________ SSRL/LCLS USER ACCOUNT INFORMATION #12;REVISED 01/6/10 - MS Why Have a User Account? Each user group

  2. Parallel Processing of Large Datasets from NanoLC-FTICR-MS Measurements

    E-Print Network [OSTI]

    van Nieuwpoort, Rob V.

    for these biomarkers Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a powerful tool becauseParallel Processing of Large Datasets from NanoLC-FTICR-MS Measurements Y. E. M. van der Burgt, I parallel processing of large mass spectral datasets in a distributed computing environment is demonstrated

  3. Boston University User Fee Structure for ICP-ES, ICP-MS and Laser Labs

    E-Print Network [OSTI]

    Hutyra, Lucy R.

    Cost per sample by laser ablation includes three spots on a sample plus an additional three spotsBoston University User Fee Structure for ICP-ES, ICP-MS and Laser Labs The Department of Earth come to BU and digest their samples in our labs with sufficient training. Laser-ICP-MS cost per sample

  4. Stanford MBA/MS Electrical Engineering Joint Degree Program Page 1 of 20 August 18, 2014

    E-Print Network [OSTI]

    Kay, Mark A.

    Stanford MBA/MS Electrical Engineering Joint Degree Program Page 1 of 20 August 18, 2014 Becky at the end of this transcript. Stanford MBA/MS Electrical Engineering Joint Degree Webinar August 18, 2014 on the Masters in Electrical Engineering and MBA Joint Degree Program. We are going to be together here for 45

  5. ENG BE/ME/MS 504: Polymers and Soft Materials GRS PY 744: Polymer Physics.

    E-Print Network [OSTI]

    Vajda, Sandor

    ENG BE/ME/MS 504: Polymers and Soft Materials GRS PY 744: Polymer Physics. Prof. Rama Bansil Class: Blackboard.bu.edu ME/MS/BE 504 PY 744 A1 POLYMERS AND SOFT MATERIALS (FALL 2012) (12FALLENGME504_A1) E with thermodynamics and statistical mechanics will be assumed. Practical applications of polymers will be discussed

  6. Name Degree Year Notes Thesis title Berg, Ronald J. MS. Zoology 1969

    E-Print Network [OSTI]

    Sheridan, Jennifer

    thermoregulation of fishes in relation to heated effluent from a steam-electric power plant (Lake Monona & 1975 MS.Distribution of fishes near Point Beach Power Plant, Lake Michigan; Ph.D. Habitat selection bluegill and three other panfish in Lake Wingra. Brauer, Garrett MS Zoology 1972 The effect of a power

  7. Gas chromatograph-mass spectrometer (GC/MS) system for quantitative analysis of reactive chemical compounds

    DOE Patents [OSTI]

    Grindstaff, Quirinus G. (Oak Ridge, TN)

    1992-01-01T23:59:59.000Z

    Described is a new gas chromatograph-mass spectrometer (GC/MS) system and method for quantitative analysis of reactive chemical compounds. All components of such a GC/MS system external to the oven of the gas chromatograph are programmably temperature controlled to operate at a volatilization temperature specific to the compound(s) sought to be separated and measured.

  8. High Power Wideband AlGaN/GaN HEMT Feedback Amplifier Module Y. Chung, S. Cai, W. Lee, Y. Lin, C. P. Wen, K. L. Wang, and T. Itoh

    E-Print Network [OSTI]

    Itoh, Tatsuo

    High Power Wideband AlGaN/GaN HEMT Feedback Amplifier Module Y. Chung, S. Cai, W. Lee, Y. Lin, C. P wideband feedback amplifier module using AlGaN/GaN high electron mobility transistor (HEMT) has been of 12 V (Vds) and a gate voltage of -3 V (Vgs). A feedback amplifier with AlGaN/GaN HEMT GaN-based HEMT

  9. Low temperature carrier redistribution dynamics in InGaN/GaN quantum wells

    SciTech Connect (OSTI)

    Badcock, T. J., E-mail: Thomas.badcock@crl.toshiba.co.uk; Dawson, P.; Davies, M. J. [School of Physics and Astronomy, Photon Science Institute, Alan Turing Building, University of Manchester, Manchester M13 9PL (United Kingdom); Kappers, M. J.; Massabuau, F. C.-P.; Oehler, F.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, 27 Charles Babbage Road, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

    2014-03-21T23:59:59.000Z

    We have studied the carrier recombination dynamics in an InGaN/GaN multiple quantum well structure as a function of emission energy and excitation density between temperatures of 10?K and 100?K. Under relatively low levels of excitation, the photoluminescence (PL) intensity and decay time of emission on the high energy side of the luminescence spectrum decrease strongly between 10?K and 50?K. In contrast, for emission detected on the low energy side of the spectrum, the PL intensity and decay time increase over the same temperature range. These results are consistent with a thermally activated carrier redistribution process in which the (temperature dependent) average timescale for carrier transfer into or out of a localised state depends on the energy of the given state. Thus, the transfer time out of shallow, weakly localised states is considerably shorter than the arrival time into more deeply localised states. This picture is consistent with carriers hopping between localisation sites in an uncorrelated disorder potential where the density of localised states decreases with increasing localisation depth, e.g., a exponential or Gaussian distribution resulting from random alloy disorder. Under significantly higher levels of excitation, the increased occupation fraction of the localised states results in a greater average separation distance between unoccupied localised states, causing a suppression of the spectral and dynamic signatures of the hopping transfer of carriers.

  10. Testing of ethylene propylene seals for the GA-4/GA-9 casks

    SciTech Connect (OSTI)

    Boonstra, R.H.

    1993-08-01T23:59:59.000Z

    The primary O-ring seal of the GA-4 and GA-9 casks was tested for leakage with a full-scale mockup of the cask lid and flange. Tests were performed at temperatures of ambient, {minus}41{degrees}, 121{degrees}, and 193{degrees}C. Shim plates between the lid and flange simulated gaps caused by thermal distortion. The testing used a helium mass spectrometer leak detector (MSLD). Results showed that the primary seal was leaktight for all test conditions. Helium permeation through the seal began in 13--23 minutes for the ambient tests and in 1--2 minutes for the tests at elevated temperatures. After each test several hours of the pumping were typically required to reduce the MSLD background reading to an acceptable level for the next test, indicating that the seal had become saturated with helium. To verify that the test results showed permeation and not real leakage, several response checks were conducted in which a calibrated leak source was inserted in the detector line near the seal. When the leak source was activated the detector responded within seconds.

  11. Impact of high energy particles in InGaP/InGaAs pseudomorphic HEMTs

    SciTech Connect (OSTI)

    Ohyama, H.; Hakata, T. [Kumamoto National Coll. of Technology, Nishigoshi, Kumamoto (Japan)] [Kumamoto National Coll. of Technology, Nishigoshi, Kumamoto (Japan); Simoen, E.; Claeys, C. [IMEC, Leuven (Belgium)] [IMEC, Leuven (Belgium); Kuroda, S. [Fujitsu Quantum Devices Ltd., Yamanashi (Japan)] [Fujitsu Quantum Devices Ltd., Yamanashi (Japan); Takami, Y. [Rikkyo Univ., Yokosuka, Kanagawa (Japan)] [Rikkyo Univ., Yokosuka, Kanagawa (Japan); Sunaga, H. [Takasaki JAERI, Takasaki, Gunma (Japan)] [Takasaki JAERI, Takasaki, Gunma (Japan)

    1998-12-01T23:59:59.000Z

    Irradiation damage and its recovery behavior resulting from thermal annealing in InGaP/InGaAs pseudomorphic HEMTs, subjected to a 20-MeV alpha ray and 220-MeV carbon, are studied for the first time. The drain current and effective mobility decrease after irradiation, while the threshold voltage increases in positive direction. The degradation of device performance increases with increasing fluence. The decrease of the mobility is thought to be due to the scattering of channel electrons with the induced lattice defects and also to the decrease of the electron density in the two dimensional electron gas (2DEG) region. The influence of the radiation source on the degradation and recovery is discussed by comparison with 1-MeV electron and 1-MeV fast neutron exposures with respect to the number of knock-on atoms and the nonionizing energy loss (NIEL). Isochronal thermal annealing for temperatures ranging from 75 to 300 C shows that the device performance degraded by the irradiation recovers completely.

  12. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect (OSTI)

    Özduran, Mustafa [Ahi Evran Üniversitesi Fen Edebiyat Fakültesi Fizik Bölümü, K?r?ehir (Turkey); Turgut, Kemal [Yüksek Lisans Ö?rencisi, K?r?ehir (Turkey); Arikan, Nihat [Ahi Evran Üniversitesi E?itim Fakültesi ?lkö?retim Bölümü, K?r?ehir (Turkey); ?yigör, Ahmet; Candan, Abdullah [Ahi Evran Üniversitesi Merkezi Ara?t?rma Laboratuvar?, K?r?ehir (Turkey)

    2014-10-06T23:59:59.000Z

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

  13. Reduced lattice temperature high-speed operation of pseudomorphic InGaAdGaAs field-effect transistors

    E-Print Network [OSTI]

    Kolodzey, James

    ,um GaAs buffer, 170 A Ino.zGao,sAs strained channel, 50 A undoped Ale,,,Ga,,,As undoped spacer, S dimensions of 0.25 x 200 pm and 0.5 X 200 pm with a source-drain spacing of 2 ,um. The MODFETs have gate dimensions of 0.35~ 100 pm and 0.47X 100 pm with a source-drain spacing of 1 ,um. The MISFETs have

  14. Optically Detected Extended X-Ray Absorption Fine Structure Study of InGaN/GaN Single Quantum Wells

    SciTech Connect (OSTI)

    Rigopoulos, N.; Hamilton, B.; Davies, G. J.; Towlson, B. M. [School of Electrical and Electronic Engineering, University of Manchester, Manchester M60 1QD (United Kingdom); Poolton, N. R. J. [Synchrotron Radiation Department, Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Dawson, P.; Graham, D. M. [School of Physics and Astronomy, University of Manchester, Manchester M60 1QD (United Kingdom); Kappers, M. J.; Humphreys, C. J. [Dept. of Materials Science and Metallurgy, University of Cambridge, Pembroke Street, Cambridge CB2 3QZ (United Kingdom); Carlson, S. [MAX-lab, Lund University, P.O. Box 118, SE- 221 00 Lund (Sweden)

    2007-04-10T23:59:59.000Z

    We have investigated the local atomic environment of the Ga atoms in an InxGa1-xN single quantum well structure using Optically Detected Extended X-ray Absorption Fine Structure (OD-EXAFS). A comparison of the OD-EXAFS data with a theoretical model shows the technique to be site selective for this particular structure and reveals that the quantum well emission originates from regions with x=0.15.

  15. Europium doping of zincblende GaN by ion implantation K. Lorenz,1,2,a

    E-Print Network [OSTI]

    As, Donat Josef

    /channeling spectrometry. A low concentration 10% of wurtzite phase inclusions was observed by XRD analysis in as-lattice parameter of wurtzite GaN W-GaN . For ZB-GaN:Eu, a large fraction of Eu ions is found on a high symmetry-GaN:Eu. The implantation damage in ZB-GaN:Eu could partly be removed by thermal annealing, but an increase in the wurtzite

  16. Electron Band Structure of MnGaN Dimiter Alexandrov1

    E-Print Network [OSTI]

    Dietz, Nikolaus

    to this orbital to be occupied. LCAO electron band structure of wurtzite MnxGa1-xN for points c1 and v15 ( = 1 of the wurtzite MnxGa1-xN are determined as well. INTRODUCTION The MnxGa1-xN semiconductor alloy is important model the MnGaN alloy on Mn content. Segregated Mn species in wurtzite GaN containing Mn

  17. D10.7.2: Results for GaAs photocathodes

    E-Print Network [OSTI]

    Xiang, R

    2013-01-01T23:59:59.000Z

    HZDR plans to apply bulk GaAs photocathode in SRF gun for high current electron source. Supported by this project, a preparation system for GaAs photocathode has been developed. The cathode plugs special for GaAs wafer have been modified and proofed in SRF gun real running conditions. Virgin GaAs wafer was tested in the SRF gun cavity, and the first GaAs activation was performed.

  18. GaN/AlN Quantum Dots for Single Qubit Emitters M. Winkelnkemper

    E-Print Network [OSTI]

    Nabben, Reinhard

    GaN/AlN Quantum Dots for Single Qubit Emitters M. Winkelnkemper , R. Seguin, S. Rodt, A. Hoffmann-plane GaN/AlN quantum dots (QDs) with focus on their potential as sources of single polarized photons emission lines from single InGaN/GaN [4­11] and GaN/AlN QDs grown on the c-plane [12­16] and a-plane [17

  19. Zeeman spectroscopy of the Fe3 center in GaN

    E-Print Network [OSTI]

    Nabben, Reinhard

    vapor deposition grown GaN Ronny Kirste, Ramón Collazo, Gordon Callsen, Markus R. Wagner, Thomas Kure et vapor deposition grown GaN Ronny Kirste,1,a) Ramo´n Collazo,2 Gordon Callsen,1 Markus R. Wagner,1 Thomas in GaN. GaN with Ga- to N-polar junctions was grown on sapphire using an AlN buffer layer. Results from

  20. p-doping-free InGaN/GaN light-emitting diode driven by three-dimensional hole gas

    SciTech Connect (OSTI)

    Zhang, Zi-Hui; Tiam Tan, Swee; Kyaw, Zabu; Liu, Wei; Ji, Yun; Ju, Zhengang; Zhang, Xueliang [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore) [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Wei Sun, Xiao, E-mail: EXWSUN@ntu.edu.sg [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electronics and Electrical Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Volkan Demir, Hilmi, E-mail: VOLKAN@stanfordalumni.org [LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); LUMINOUS Centre of Excellence for Semiconductor Lighting and Displays, School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore (Singapore); Department of Electrical and Electronics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey); Department of Physics, UNAM-Institute of Material Science and Nanotechnology, Bilkent University, Ankara TR-06800 (Turkey)

    2013-12-23T23:59:59.000Z

    Here, GaN/Al{sub x}Ga{sub 1-x}N heterostructures with a graded AlN composition, completely lacking external p-doping, are designed and grown using metal-organic-chemical-vapour deposition (MOCVD) system to realize three-dimensional hole gas (3DHG). The existence of the 3DHG is confirmed by capacitance-voltage measurements. Based on this design, a p-doping-free InGaN/GaN light-emitting diode (LED) driven by the 3DHG is proposed and grown using MOCVD. The electroluminescence, which is attributed to the radiative recombination of injected electrons and holes in InGaN/GaN quantum wells, is observed from the fabricated p-doping-free devices. These results suggest that the 3DHG can be an alternative hole source for InGaN/GaN LEDs besides common Mg dopants.

  1. Fabrication of Two-Dimensional Photonic Crystals in AlGaInP/GaInP Membranes by Inductively Coupled Plasma Etching

    E-Print Network [OSTI]

    Chen, A.

    The fabrication process of two-dimensional photonic crystals in an AlGaInP/GaInP multi-quantum-well membrane structure is developed. The process includes high resolution electron-beam lithography, pattern transfer into ...

  2. Advanced Gate Technologies for State-of-the-art f[subscript T] in AlGaN/GaN HEMTs

    E-Print Network [OSTI]

    Chung, Jinwook

    In this paper, the lower-than-expected frequency performance observed in many AlGaN/GaN high electron mobility transistors (HEMTs) has been attributed to a significant drop of the intrinsic small-signal transconductance ...

  3. Realization of compressively strained GaN films grown on Si(110) substrates by inserting a thin AlN/GaN superlattice interlayer

    SciTech Connect (OSTI)

    Shen, X. Q.; Takahashi, T.; Kawashima, H.; Ide, T.; Shimizu, M. [Advanced Power Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-1, Central 2, Tsukuba-shi, Ibaraki 305-8568 (Japan)

    2012-07-16T23:59:59.000Z

    We investigate the strain properties of GaN films grown by plasma-assisted molecular beam epitaxy on Si(110) substrates. It is found that the strain of the GaN film can be converted from a tensile to a compressive state simply by inserting a thin AlN/GaN superlattice structure (SLs) within the GaN film. The GaN layers seperated by the SLs can have different strain states, which indicates that the SLs plays a key role in the strain modulation during the growth and the cooling down processes. Using this simple technique, we grow a crack-free GaN film exceeding 2-{mu}m-thick. The realization of the compressively strained GaN film makes it possible to grow thick GaN films without crack generation on Si substrates for optic and electronic device applications.

  4. Influence of InGaN sub-quantum-well on performance of InAlN/GaN/InAlN resonant tunneling diodes

    SciTech Connect (OSTI)

    Chen, Haoran; Yang, Lin'an, E-mail: layang@xidian.edu.cn; Hao, Yue [State Key Discipline Laboratory of Wide Bandgap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071 (China)

    2014-08-21T23:59:59.000Z

    The resonant tunneling mechanism of the GaN based resonant tunneling diode (RTD) with an InGaN sub-quantum-well has been investigated by means of numerical simulation. At resonant-state, Electrons in the InGaN/InAlN/GaN/InAlN RTD tunnel from the emitter region through the aligned discrete energy levels in the InGaN sub-quantum-well and GaN main-quantum-well into the collector region. The implantation of the InGaN sub-quantum-well alters the dominant transport mechanism, increase the transmission coefficient and give rise to the peak current and peak-to-valley current ratio. We also demonstrate that the most pronounced negative-differential-resistance characteristic can be achieved by choosing appropriately the In composition of In{sub x}Ga{sub 1?x}N at around x?=?0.06.

  5. Semipolar (202{sup ¯}1) GaN and InGaN quantum wells on sapphire substrates

    SciTech Connect (OSTI)

    Leung, Benjamin; Wang, Dili; Kuo, Yu-Sheng; Xiong, Kanglin; Song, Jie; Chen, Danti; Park, Sung Hyun; Han, Jung [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520 (United States); Hong, Su Yeon; Choi, Joo Won [Seoul Viosys Co., Ltd., Ansan City, Kyunggi-do 425-851 (Korea, Republic of)

    2014-06-30T23:59:59.000Z

    Here, we demonstrate a process to produce planar semipolar (202{sup ¯}1) GaN templates on sapphire substrates. We obtain (202{sup ¯}1) oriented GaN by inclined c-plane sidewall growth from etched sapphire, resulting in single crystal material with on-axis x-ray diffraction linewidth below 200?arc sec. The surface, composed of (101{sup ¯}1) and (101{sup ¯}0) facets, is planarized by the chemical-mechanical polishing of full 2?in. wafers, with a final surface root mean square roughness of <0.5?nm. We then analyze facet formation and roughening mechanisms on the (202{sup ¯}1) surface and establish a growth condition in N{sub 2} carrier gas to maintain a planar surface for further device layer growth. Finally, the capability of these semipolar (202{sup ¯}1) GaN templates to produce high quality device structures is verified by the growth and characterization of InGaN/GaN multiple quantum well structures. It is expected that the methods shown here can enable the benefits of using semipolar orientations in a scalable and practical process and can be readily extended to achieve devices on surfaces using any orientation of semipolar GaN on sapphire.

  6. Effects of high-temperature AIN buffer on the microstructure of AlGaN/GaN HEMTs

    SciTech Connect (OSTI)

    Coerekci, S., E-mail: scorekci@kirklareli.edu.tr [K Latin-Small-Letter-Dotless-I rklareli University, Department of Physics (Turkey); Oeztuerk, M. K. [Gazi University, Department of Physics (Turkey); Yu, Hongbo [Bilkent University, Nanotechnology Research Center (Turkey); Cakmak, M.; Oezcelik, S. [Gazi University, Department of Physics (Turkey); Oezbay, E. [Bilkent University, Nanotechnology Research Center, Department of Physics, Department of Electrical and Electronics Engineering (Turkey)

    2013-06-15T23:59:59.000Z

    Effects on AlGaN/GaN high-electron-mobility transistor structure of a high-temperature AlN buffer on sapphire substrate have been studied by high-resolution x-ray diffraction and atomic force microscopy techniques. The buffer improves the microstructural quality of GaN epilayer and reduces approximately one order of magnitude the edge-type threading dislocation density. As expected, the buffer also leads an atomically flat surface with a low root-mean-square of 0.25 nm and a step termination density in the range of 10{sup 8} cm{sup -2}. Due to the high-temperature buffer layer, no change on the strain character of the GaN and AlGaN epitaxial layers has been observed. Both epilayers exhibit compressive strain in parallel to the growth direction and tensile strain in perpendicular to the growth direction. However, an high-temperature AlN buffer layer on sapphire substrate in the HEMT structure reduces the tensile stress in the AlGaN layer.

  7. Polarization self-screening in [0001] oriented InGaN/GaN light-emitting diodes for improving the electron injection efficiency

    E-Print Network [OSTI]

    Demir, Hilmi Volkan

    GaN light-emitting diodes: Efficiency-limiting processes at high injection J. Vac. Sci. Technol. A 31

  8. Self-heating study of an AlGaN/GaN-based heterostructure field-effect transistor using ultraviolet micro-Raman scattering

    E-Print Network [OSTI]

    Holtz, Mark

    Self-heating study of an AlGaN/GaN-based heterostructure field-effect transistor using ultraviolet We report micro-Raman studies of self-heating in an AlGaN/GaN heterostructure field-effect transistorC substrate, at the same lateral position. Combined, we depth profile the self-heating. Measured T in the 2DEG

  9. Prediction of Ordering and Spontaneous Rotation of Epitaxial Habits in Substrate-Coherent InGaN and GaAsSb

    SciTech Connect (OSTI)

    Liu, J. Z.; Trimarchi, G.; Zunger, A.

    2009-01-01T23:59:59.000Z

    Coherently strained In{sub 0.5}Ga{sub 0.5}N on GaN and CaO substrates are theoretically predicted to show stable ordering in the chalcopyrite structure, as is Ga{sub 2}AsSb on GaAs and InP substrates. Depending on the substrate and the film concentration, we predict a spontaneous rotation of the stablest chalcopyrite film axis from perpendicular to parallel to the (001) substrate.

  10. Spatial distribution of structural degradation under high-power stress in AlGaN/GaN high electron mobility transistors

    E-Print Network [OSTI]

    del Alamo, Jesús A.

    and high temperature, the latter being a result of de- vice self-heating. A complicating factor degradation of AlGaN/GaN high electron mobility transistors was investigated under high-power electrical electrical degradation that was mostly driven by an electric field across the AlGaN barrier. Under high

  11. Growth, microstructure, and luminescent properties of direct-bandgap InAlP on relaxed InGaAs on GaAs substrates

    E-Print Network [OSTI]

    an impact on the luminescence spectrum. While similar to InGaP in many ways, the greater tendency for phase as the InGaP system, but still has desirable properties. In0.48Al0.52P is lattice- matched to GaAs and has

  12. Contribution of alloy clustering to limiting the two-dimensional electron gas mobility in AlGaN/GaN and InAlN/GaN heterostructures: Theory and experiment

    SciTech Connect (OSTI)

    Ahmadi, Elaheh; Mishra, Umesh K. [Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States); Chalabi, Hamidreza [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305 (United States); Kaun, Stephen W.; Shivaraman, Ravi; Speck, James S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)

    2014-10-07T23:59:59.000Z

    The influence of alloy clustering on fluctuations in the ground state energy of the two-dimensional electron gas (2DEG) in AlGaN/GaN and InAlN/GaN heterostructures is studied. We show that because of these fluctuations, alloy clustering degrades the mobility even when the 2DEG wavefunction does not penetrate the alloy barrier unlike alloy disorder scattering. A comparison between the results obtained for AlGaN/GaN and InAlN/GaN heterostructures shows that alloy clustering limits the 2DEG mobility to a greater degree in InAlN/GaN heterostructures. Our study also reveals that the inclusion of an AlN interlayer increases the limiting mobility from alloy clustering. Moreover, Atom probe tomography is used to demonstrate the random nature of the fluctuations in the alloy composition.

  13. Review of radiation damage in GaN-based materials and devices

    SciTech Connect (OSTI)

    Pearton, Stephen J.; Deist, Richard [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32606 (United States)] [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32606 (United States); Ren, Fan; Liu, Lu [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)] [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States); Polyakov, Alexander Y. [Institute of Rare Metals, Moscow, 119017, B. Tolmachevsky, 5 (Russian Federation)] [Institute of Rare Metals, Moscow, 119017, B. Tolmachevsky, 5 (Russian Federation); Kim, Jihyun [Department of Chemical and Biological Engineering, Korea University, Anam-dong, Sungbuk-gu, Seoul, 136-713 (Korea, Republic of)] [Department of Chemical and Biological Engineering, Korea University, Anam-dong, Sungbuk-gu, Seoul, 136-713 (Korea, Republic of)

    2013-09-15T23:59:59.000Z

    A review of the effects of proton, neutron, ?-ray, and electron irradiation on GaN materials and devices is presented. Neutron irradiation tends to create disordered regions in the GaN, while the damage from the other forms of radiation is more typically point defects. In all cases, the damaged region contains carrier traps that reduce the mobility and conductivity of the GaN and at high enough doses, a significant degradation of device performance. GaN is several orders of magnitude more resistant to radiation damage than GaAs of similar doping concentrations. In terms of heterostructures, preliminary data suggests that the radiation hardness decreases in the order AlN/GaN > AlGaN/GaN > InAlN/GaN, consistent with the average bond strengths in the Al-based materials.

  14. 444 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 14, NO. 4, APRIL 2002 Low-Threshold Strain-Compensated InGaAs(N)

    E-Print Network [OSTI]

    Gilchrist, James F.

    lasers utilizing strain-compensating InGaP­GaAsP buffer layers and GaAs0 85P0 15 barrier layers, grownGaAs lower cladding layers, are significantly improved through the use of an InGaP­GaAsP buffer layer. II As and p-In Ga P, respectively. Buffer layers of 2650-Å n-InGaP ( ppm), and 20-Å highly-tensile GaAs P

  15. Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe

    E-Print Network [OSTI]

    A. E. Nikolaenko; E. A. Chekhovich; M. N. Makhonin; I. W. Drouzas; A. B. Vankov; J. Skiba-Szymanska; M. S. Skolnick; P. Senellart; A. Lemaitre; A. I. Tartakovskii

    2009-01-15T23:59:59.000Z

    Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

  16. Active region based on graded-gap InGaN/GaN superlattices for high-power 440- to 470-nm light-emitting diodes

    SciTech Connect (OSTI)

    Tsatsulnikov, A. F., E-mail: Andrew@beam.ioffe.ru; Lundin, W. V.; Sakharov, A. V.; Zavarin, E. E.; Usov, S. O.; Nikolaev, A. E.; Cherkashin, N. A.; Ber, B. Ya.; Kazantsev, D. Yu. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Mizerov, M. N. [Russian Academy of Sciences, Center for Microelectronics, Ioffe Physicotechnical Institute (Russian Federation); Park, Hee Seok [Samsung Electro-Mechanics Co. Ltd. (Korea, Republic of); Hytch, M.; Hue, F. [National Center for Scientific Research, Center for Material Elaboration and Structural Studies (France)

    2010-01-15T23:59:59.000Z

    The structural and optical properties of light-emitting diode structures with an active region based on ultrathin InGaN quantum wells limited by short-period InGaN/GaN superlattices from both sides have been investigated. The dependences of the external quantum efficiency on the active region design are analyzed. It is shown that the use of InGaN/GaN structures as limiting graded-gap short-period superlattices may significantly increase the quantum efficiency.

  17. Nano-scale luminescence characterization of individual InGaN/GaN quantum wells stacked in a microcavity using scanning transmission electron microscope cathodoluminescence

    SciTech Connect (OSTI)

    Schmidt, Gordon, E-mail: Gordon.Schmidt@ovgu.de; Müller, Marcus; Veit, Peter; Bertram, Frank; Christen, Jürgen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg (Germany); Glauser, Marlene; Carlin, Jean-François; Cosendey, Gatien; Butté, Raphaël; Grandjean, Nicolas [Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2014-07-21T23:59:59.000Z

    Using cathodoluminescence spectroscopy directly performed in a scanning transmission electron microscope at liquid helium temperatures, the optical and structural properties of a 62 InGaN/GaN multiple quantum well embedded in an AlInN/GaN based microcavity are investigated at the nanometer scale. We are able to spatially resolve a spectral redshift between the individual quantum wells towards the surface. Cathodoluminescence spectral linescans allow directly visualizing the critical layer thickness in the quantum well stack resulting in the onset of plastic relaxation of the strained InGaN/GaN system.

  18. SiO2 Passivation Effects on the Leakage Current in Dual-Gate AlGaN/GaN High Electron Mobility Transistors

    E-Print Network [OSTI]

    Seo, Kwang Seok

    was grown on c-plane sapphire substrate by MOCVD. Undoped 30 nm-thick Al0.26Ga0.74N and Fe-doped 3 m GaN substrate 3 nm undoped GaN 0.26 0.74 Source DrainMain-GateSiO2 2DEG SiO2 SiO2 Additional Gate 5 m3 m3 m 3 mSiO2 Passivation Effects on the Leakage Current in Dual-Gate AlGaN/GaN High Electron Mobility

  19. Strain relaxation in GaN/Al{sub x}Ga{sub 1-x}N superlattices grown by plasma-assisted molecular-beam epitaxy

    SciTech Connect (OSTI)

    Kotsar, Y.; Bellet-Amalric, E.; Das, A.; Monroy, E. [CEA-Grenoble, INAC/SP2M/NPSC, 17 Rue des Martyrs, 38054 Grenoble cedex 9 (France); Doisneau, B. [SIMaP, Grenoble INP, Domaine Universitaire, BP 75, 38402 Saint Martin d'Heres (France); Sarigiannidou, E. [LMGP, Grenoble INP, 3 Parvis Louis Neel, BP 257, 38016 Grenoble cedex 1 (France)

    2011-08-01T23:59:59.000Z

    We have investigated the misfit relaxation process in GaN/Al{sub x}Ga{sub 1-x}N (x = 0.1, 0.3, 0.44) superlattices (SL) deposited by plasma-assisted molecular beam epitaxy. The SLs under consideration were designed to achieve intersubband absorption in the mid-infrared spectral range. We have considered the case of growth on GaN (tensile stress) and on AlGaN (compressive stress) buffer layers, both deposited on GaN-on-sapphire templates. Using GaN buffer layers, the SL remains almost pseudomorphic for x = 0.1, 0.3, with edge-type threading dislocation densities below 9 x 10{sup 8} cm{sup -2} to 2 x 10{sup 9} cm{sup -2}. Increasing the Al mole fraction to 0.44, we observe an enhancement of misfit relaxation resulting in dislocation densities above 10{sup 10} cm{sup -2}. In the case of growth on AlGaN, strain relaxation is systematically stronger, with the corresponding increase in the dislocation density. In addition to the average relaxation trend of the SL, in situ measurements indicate a periodic fluctuation of the in-plane lattice parameter, which is explained by the different elastic response of the GaN and AlGaN surfaces to the Ga excess at the growth front. The results are compared with GaN/AlN SLs designed for near-infrared intersubband absorption.

  20. Zinc-blende (Cubic) GaN and AlGaN Layers, Structures and Bulk Crystals by Molecular Beam Epitaxy

    SciTech Connect (OSTI)

    Novikov, Sergei V.; Zainal, Norzaini; Akimov, Andrey V.; Staddon, Chris R.; Foxon, C. Thomas; Kent, Anthony J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2010-11-01T23:59:59.000Z

    We have studied the growth of zinc-blende GaN and AlGaN layers, structures and bulk crystals by molecular beam epitaxy (MBE). We have developed a process for growth by MBE of free-standing cubic GaN layers. Undoped thick cubic GaN films were grown on semi-insulating GaAs (001) substrates by a modified plasma-assisted molecular beam epitaxy (PA-MBE) method and were removed from the GaAs substrate after the growth. The resulting free-standing GaN wafers with thicknesses in the 30-100 {mu}m range may be used as substrates for further epitaxy of cubic GaN-based structures and devices. We have developed procedures to cleave the wafers into 10x10 mm{sup 2} square substrates and to polish them to produce epi-ready surfaces. The first GaN/InGaN LEDs on our zinc-blende GaN substrates have been demonstrated by our collaborators at Sharp Laboratories of Europe.

  1. GaAs-based high temperature electrically pumped polariton laser

    SciTech Connect (OSTI)

    Baten, Md Zunaid; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu; Frost, Thomas; Deshpande, Saniya; Das, Ayan [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lubyshev, Dimitri; Fastenau, Joel M.; Liu, Amy W. K. [IQE, Inc., 119 Technology Drive, Bethlehem, Pennsylvania 18015 (United States)

    2014-06-09T23:59:59.000Z

    Strong coupling effects and polariton lasing are observed at 155?K with an edge-emitting GaAs-based microcavity diode with a single Al{sub 0.31}Ga{sub 0.69}As/Al{sub 0.41}Ga{sub 0.59}As quantum well as the emitter. The threshold for polariton lasing is observed at 90?A/cm{sup 2}, accompanied by a reduction of the emission linewidth to 0.85?meV and a blueshift of the emission wavelength by 0.89?meV. Polariton lasing is confirmed by the observation of a polariton population redistribution in momentum space and spatial coherence. Conventional photon lasing is recorded in the same device at higher pump powers.

  2. Spectroscopic ellipsometry studies of GaN films deposited by reactive rf sputtering of GaAs target

    SciTech Connect (OSTI)

    Biswas, A.; Bhattacharyya, D.; Sahoo, N. K. [Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Yadav, Brajesh S.; Major, S. S. [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400 076 (India); Srinivasa, R. S. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400 076 (India)

    2008-04-15T23:59:59.000Z

    GaN films have been deposited by reactive rf sputtering of GaAs target in 100% nitrogen ambient on quartz substrates at different substrate temperatures ranging from room temperature to 700 deg. C. A series of films, from arsenic-rich amorphous to nearly arsenic-free polycrystalline hexagonal GaN, has been obtained. The films have been characterized by phase modulated spectroscopic ellipsometry to obtain the optical parameters, viz., fundamental band gap, refractive index, and extinction coefficient, and to understand their dependence on composition and microstructure. A generalized optical dispersion model has been used to carry out the ellipsometric analysis for amorphous and polycrystalline GaN films and the variation of the optical parameters of the films has been studied as a function of substrate temperature. The refractive index values of polycrystalline films with preferred orientation of crystallites are slightly higher (2.2) compared to those for amorphous and randomly oriented films. The dominantly amorphous GaN film shows a band gap of 3.47 eV, which decreases to 3.37 eV for the strongly c-axis oriented polycrystalline film due to the reduction in amorphous phase content with increase in substrate temperature.

  3. High optical and structural quality of GaN epilayers grown on (2{sup ¯}01) ?-Ga{sub 2}O{sub 3}

    SciTech Connect (OSTI)

    Muhammed, M. M.; Roqan, I. S., E-mail: iman.roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Peres, M.; Franco, N.; Lorenz, K. [IPFN, Instituto Superior Técnico (IST), Campus Tecnológico e Nuclear, Estrada Nacional 10, P-2695-066 Bobadela LRS (Portugal); Yamashita, Y.; Morishima, Y.; Sato, S.; Kuramata, A. [Tamura Corporation, Sayama, Saitama 350-1328 (Japan)

    2014-07-28T23:59:59.000Z

    Producing highly efficient GaN-based optoelectronic devices has been a challenge for a long time due to the large lattice mismatch between III-nitride materials and the most common substrates, which causes a high density of threading dislocations. Therefore, it is essential to obtain alternative substrates with small lattice mismatches, appropriate structural, thermal and electrical properties, and a competitive price. Our results show that (2{sup ¯}01) oriented ?-Ga{sub 2}O{sub 3} has the potential to be used as a transparent and conductive substrate for GaN-growth. Photoluminescence spectra of thick GaN layers grown on (2{sup ¯}01) oriented ?-Ga{sub 2}O{sub 3} are found to be dominated by intense bandedge emission. Atomic force microscopy studies show a modest threading dislocation density of ?10{sup 8?}cm{sup ?2}. X-ray diffraction studies show the high quality of the single-phase wurtzite GaN thin film on (2{sup ¯}01) ?-Ga{sub 2}O{sub 3} with in-plane epitaxial orientation relationships between the ?-Ga{sub 2}O{sub 3} and the GaN thin film defined by (010) ?-Ga{sub 2}O{sub 3} || (112{sup ¯}0) GaN and (2{sup ¯}01) ?-Ga{sub 2}O{sub 3} || (0001) GaN leading to a lattice mismatch of ?4.7%. Complementary Raman spectroscopy indicates that the quality of the GaN epilayer is high.

  4. Updated 7-12 Ms. Markowich is currently the Director of the Battlespace Simulation Department (AIR-5.4) at

    E-Print Network [OSTI]

    and complete adequate testing to demonstrate suitable and effective operations in the joint battlespace. Ms and simulation in a Battlespace environment. Ms. Markowich is the Department of Navy Modeling and Simulation and unmanned partnerships across the Navy and Joint Services. Ms. Markowich previously served as the Deputy

  5. Redistribution of Implanted Dopants in GaN

    SciTech Connect (OSTI)

    Fu, M.; Gao, X.A.; Han, J.; Pearton, S.J.; Rieger, D.J.; Scarvepalli, V. Sekhar, J.A.; Shul, R.J.; Singh, R.K.; Wilson, R.G.; Zavada, J.M.; Zolper, J.C.

    1998-11-20T23:59:59.000Z

    Donor (S, Se and Te) and acceptor (Mg, Be and C) dopants have been implanted into GaN at doses of 3-5x1014 cm-2 and annealed at temperatures up to 1450 *C. No redistribution of any of the elements is detectable by Secondary Ion Mass Spectrometry, except for Be, which displays an apparent damage-assisted diffusion at 900 "C. At higher temperatures there is no further movement of the Be, suggesting that the point defect flux that assists motion at lower temperatures has been annealed. Effective diffusivities are <2X 1013 cm2.sec-1 at 1450 `C for each of the dopants in GaN.

  6. Simple intrinsic defects in GaAs : numerical supplement.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2012-04-01T23:59:59.000Z

    This Report presents numerical tables summarizing properties of intrinsic defects in gallium arsenide, GaAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz and O.A. von Lilienfeld, 'Simple intrinsic defects in GaAs', Modelling Simul. Mater. Sci Eng., Vol. 17, 084007 (2009), and intended for use as reference tables for a defect physics package in device models. The numerical results for density functional theory calculations of properties of simple intrinsic defects in gallium arsenide are presented.

  7. GaN for x-ray detection

    SciTech Connect (OSTI)

    Duboz, Jean-Yves; Lauegt, Marguerite; Schenk, David [CRHEA, CNRS, rue Bernard Gregory, Sophia Antipolis, F-06560 Valbonne (France); Beaumont, Bernard [Lumilog, 2720 chemin de saint Bernard, F-06220 Vallauris (France); Reverchon, Jean-Luc [THALES R and T, route departementale 128, F-91767 Palaiseau Cedex (France); Wieck, Andreas D.; Zimmerling, Tino [Fakultaet fuer Physik und Astronomie, D-44780 Bochum (Germany)

    2008-06-30T23:59:59.000Z

    The potential of GaN based materials for x-ray detection is investigated. The absorption coefficient in GaN is measured as a function of photon energy between 6 and 40 keV. Metal-semiconductor-metal photodetectors are fabricated and characterized. The response dependence on bias, the temporal dynamics, and the response dependence on detector geometry all together point toward a mixing of photovoltaic and photoconductive effects. Thanks to a large photoconductive gain, the detector has a decent responsivity at the expense of a large response time.

  8. Glass particles produced by laser ablation for ICP-MS measurements

    E-Print Network [OSTI]

    Gonzalez, J.; Liu, C.; Wen, S.; Mao, X.; Russo, R.E.

    2008-01-01T23:59:59.000Z

    Glass particles produced by laser ablation for ICP-MS266nm) was used to generate glass particles from two sets ofWhen the current data on glass were compared with the metal

  9. Training is sponsoring two MS PowerPoint Courses. The course...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Training is sponsoring two MS PowerPoint Courses. The course options feature level 1 and level 2. This email is to gauge interest. The associated cost per class is 200.00. If...

  10. Daniel A. Goldstein 501 Campbell Hall #3411 1 Cyclotron Road MS 50B-4206

    E-Print Network [OSTI]

    Backer, Don

    Daniel A. Goldstein 501 Campbell Hall #3411 1 Cyclotron Road MS 50B-4206 Department of Astronomy., Brown, P.J., Finley, D. A., Fischer, J., Goldstein, D., et al. DES13S2cmm: The First Superluminous

  11. THE NOTRE DAME INDUCTIVELY COUPLED PLASMA -MASS SPECTROMETRY (ICP-MS)

    E-Print Network [OSTI]

    the PQII STE ICP-MS, Electrothermal Vaporization, and Laser Ablation units The report supercedes STE, LaserProbe (tuned to 266 nm, but with 532 nm and 1046 nm capabilities), CETAC Ultrasonic

  12. Engineering (MS, PhD) www.grad.clemson.edu/brochure/IndustEng

    E-Print Network [OSTI]

    Duchowski, Andrew T.

    maintenance. · The Advanced Quality Engineering Laboratory focuses on research to discover scientific design, reliability engineering, tolerance design, human-machine collaborative design optimizationIndustrial Engineering (MS, PhD) www.grad.clemson.edu/brochure/IndustEng #12;Introduction

  13. SOLID STATE ELECTRONICS ECE 103 M.S. COMPREHENSIVE EXAM SPRING 2013

    E-Print Network [OSTI]

    Wang, Deli

    SOLID STATE ELECTRONICS ­ ECE 103 M.S. COMPREHENSIVE EXAM SPRING 2013 1. Semiconductor fundamentals-type Si sample with one end heavily doped so that the carrier concentration is 10 times greater than

  14. TEXTS OF EMPOWERMENT: A FUNCTIONAL RHETORICAL ANALYSIS OF MS. MAGAZINE IN THE FIRST FIVE YEARS

    E-Print Network [OSTI]

    Partlow Lefevre, Sarah Taylor

    2009-07-21T23:59:59.000Z

    Ms. was the first mass mediated feminist magazine in the United States and has often been identified as an icon of the feminist movement. This study examines three rhetorical sites in the magazine during the first five ...

  15. Repres rapides pour dbuter avec MsOffice 2007 Le logo identificateur de

    E-Print Network [OSTI]

    Skorobogatiy, Maksim

    Repères rapides pour débuter avec MsOffice 2007 Le logo identificateur de l'application cache des menus... Il faut cliquer sur le logo pour avoir accès aux icônes ouvrir, enregistrer, etc. #12;Les

  16. Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

    SciTech Connect (OSTI)

    Edmunds, C.; Malis, O., E-mail: omalis@purdue.edu [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Shao, J. [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); Shirazi-HD, M. [Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Manfra, M. J. [Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States); Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States); School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

    2014-07-14T23:59:59.000Z

    We demonstrate THz intersubband absorption (15.6–26.1?meV) in m-plane AlGaN/GaN quantum wells. We find a trend of decreasing peak energy with increasing quantum well width, in agreement with theoretical expectations. However, a blue-shift of the transition energy of up to 14?meV was observed relative to the calculated values. This blue-shift is shown to decrease with decreasing charge density and is, therefore, attributed to many-body effects. Furthermore, a??40% reduction in the linewidth (from roughly 8 to 5?meV) was obtained by reducing the total sheet density and inserting undoped AlGaN layers that separate the wavefunctions from the ionized impurities in the barriers.

  17. High performance double pulse doped pseudomorphic AlGaAs/InGaAs transistors grown by molecular-beam epitaxy

    SciTech Connect (OSTI)

    Hoke, W.E.; Lyman, P.S.; Labossier, W.H.; Brierley, S.K.; Hendriks, H.T.; Shanfield, S.R.; Aucoin, L.M.; Kazior, T.E. [Raytheon Research Division, Lexington, MA (United States)] [Raytheon Research Division, Lexington, MA (United States)

    1992-05-01T23:59:59.000Z

    Double pulse doped AlGaAs/InGaAs pseudomorphic high electron mobility transistors have been grown by molecular-beam epitaxy on GaAs substrates. Hall mobilities in excess of 7100 cm{sup 2}/V s at 300 K and 25000 cm{sup 2}/V s at 77 K are obtained with a sheet density of 3 x 10{sup 12} cm{sup {minus}2}. Photoluminescence measurements indicate that two electronic subbands are occupied, and the subband energies are determined. The doping pulses are resolved in secondary ion mass spectrometry measurements. Using a double recess process, transistors have been fabricated that have produced state of the art microwave performance. At 10 GHz a 1.2 mm device has simultaneously achieved a power added efficiency of 70%, output power of 0.97 W, and gain of 10 dB. 17 refs., 5 figs., 1 tab.

  18. Characteristics of InGaP/InGaAs pseudomorphic high electron mobility transistors with triple delta-doped sheets

    SciTech Connect (OSTI)

    Chu, Kuei-Yi [National Cheng-Kung University, Institute of Microelectronics, Department of Electrical Engineering (China); Chiang, Meng-Hsueh, E-mail: mhchiang@niu.edu.tw; Cheng, Shiou-Ying, E-mail: sycheng@niu.edu.tw [National II an University, Department of Electronic Engineering (China); Liu, Wen-Chau [National Cheng-Kung University, Institute of Microelectronics, Department of Electrical Engineering (China)

    2012-02-15T23:59:59.000Z

    Fundamental and insightful characteristics of InGaP/InGaAs double channel pseudomorphic high electron mobility transistors (DCPHEMTs) with graded and uniform triple {delta}-doped sheets are coomprehensively studied and demonstrated. To gain physical insight, band diagrams, carrier densities, and direct current characteristics of devices are compared and investigated based on the 2D semiconductor simulator, Atlas. Due to uniform carrier distribution and high electron density in the double InGaAs channel, the DCPHEMT with graded triple {delta}-doped sheets exhibits better transport properties, higher and linear transconductance, and better drain current capability as compared with the uniformly triple {delta}-doped counterpart. The DCPHEMT with graded triple {delta}-doped structure is fabricated and tested, and the experimental data are found to be in good agreement with simulated results.

  19. High-performance broadband optical coatings on InGaN/GaN solar cells for multijunction device integration

    SciTech Connect (OSTI)

    Young, N. G., E-mail: ngyoung@engineering.ucsb.edu; Farrell, R. M.; Iza, M.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Perl, E. E.; Keller, S. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Bowers, J. E.; Nakamura, S.; DenBaars, S. P. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2014-04-21T23:59:59.000Z

    We demonstrate InGaN/GaN multiple quantum well solar cells grown by metalorganic chemical vapor deposition on a bulk (0001) substrate with high-performance broadband optical coatings to improve light absorption. A front-side anti-reflective coating and a back-side dichroic mirror were designed to minimize front surface reflections across a broad spectral range and maximize rear surface reflections only in the spectral range absorbed by the InGaN, making the cells suitable for multijunction solar cell integration. Application of optical coatings increased the peak external quantum efficiency by 56% (relative) and conversion efficiency by 37.5% (relative) under 1 sun AM0 equivalent illumination.

  20. Degradation of InGaN/GaN laser diodes investigated by micro-cathodoluminescence and micro-photoluminescence

    SciTech Connect (OSTI)

    Meneghini, M., E-mail: matteo.meneghini@dei.unipd.it; Carraro, S.; Meneghesso, G.; Trivellin, N.; Zanoni, E. [Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova (Italy)] [Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova (Italy); Mura, G. [University of Cagliari, Piazza d'Armi, 09123 Cagliari (Italy)] [University of Cagliari, Piazza d'Armi, 09123 Cagliari (Italy); Rossi, F.; Salviati, G. [IMEM-National Council of Research, Parco Area delle Scienze 37/A, 43124 Parma (Italy)] [IMEM-National Council of Research, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Holc, K.; Weig, T.; Wagner, J. [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastraße 72, 79108 Freiburg (Germany)] [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastraße 72, 79108 Freiburg (Germany); Schade, L.; Karunakaran, M. A. [IMTEK, Freiburg University, Georges-Köhler-Allee 103 D, 79110 Freiburg (Germany)] [IMTEK, Freiburg University, Georges-Köhler-Allee 103 D, 79110 Freiburg (Germany); Schwarz, U. T. [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastraße 72, 79108 Freiburg (Germany) [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastraße 72, 79108 Freiburg (Germany); IMTEK, Freiburg University, Georges-Köhler-Allee 103 D, 79110 Freiburg (Germany)

    2013-12-02T23:59:59.000Z

    We present an investigation of the degradation of InGaN/GaN laser diodes grown on a GaN substrate. The results indicate that: (i) Ageing induces a significant increase in the threshold current (Ith) of the lasers, which is attributed to an increase in non-radiative recombination; (ii) Ith increase is correlated to a decrease in the micro-cathodoluminescence signal measured (after the removal of the top metallization) in the region under the ridge; (iii) micro-photoluminescence measurements indicate that constant current stress increases non-radiative recombination within the quantum wells (and not only within the barriers), and induces an increase in the emission wavelength of the degraded region.