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1

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,...

2

Siemens Pittsburgh, PA Novelis Corporation Atlanta, GA  

E-Print Network [OSTI]

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

McGaughey, Alan

3

1ACM SIGCSE'14, Atlanta, GA Using Gamification in Technical  

E-Print Network [OSTI]

1ACM SIGCSE'14, Atlanta, GA Using Gamification in Technical Higher Education: An XP Report. Epema, An Experience Report on Using Gamification in Technical Higher Education, ACM SIGCSE'14. http's not you, it's me · New ambition of GamificationU (Top-20 Eng/Tech*) ·

Iosup, Alexandru

4

In: Proceedings of the 1995 International environmental conference; 1995 May 7-10; Atlanta, GA. Atlanta, GA: TAPPI PRESS: 445-448; 1995.  

E-Print Network [OSTI]

. Atlanta, GA: TAPPI PRESS: 445-448; 1995. ENVIRONMENTALLY SOUND ALTERNATIVES FOR UPGRADING MIXED OFFICE-value mixed office waste. Benefits of enzyme deinking include effective toner removal, improved effluent. Benefits of fiber loading include utilization of waste carbon dioxide from stack gases, extended fiber

Abubakr, Said

5

E-Print Network 3.0 - atlanta ga usa Sample Search Results  

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

Physics and Astronomy, Georgia State University, Atlanta, Georgia... 30303, USA 3 NDP Optronics, Mableton, Georgia 30126, USA *Corresponding author: wzshen... -band imaging device,...

6

Impacts of cool cities on air quality: A preliminary modeling assessment for Nashville TN, Dallas TX and Atlanta GA  

SciTech Connect (OSTI)

Previous atmospheric modeling efforts that concentrated on the Los Angeles Basin suggested beneficial and significant air quality impacts from cool cities strategies. This paper discusses an extension of similar modeling efforts to three regions, Atlanta GA, Dallas - Ft. Worth TX, and Nashville TN, that experience smog and air quality problems. According to the older ozone air quality standard (120 ppb), these regions were classified as serious, moderate, and marginal, respectively, but may be out of compliance with respect to the newer, 80-ppb/8-hours standard. Results from this exploratory modeling work suggest a range of possible impacts on meteorological and air quality conditions. For example, peak ozone concentrations during each region's respective episode could be decreased by 1-6 ppb (conservative and optimistic scenarios, respectively) in Nashville, 5-15 ppb in Dallas - Fort Worth, and 5-12 ppb in Atlanta following implementation of cool cities. The reductions are generally smaller than those obtained from simulating the Los Angeles Basin but are still significant. In all regions, the simulations suggest, the net, domain-wide effects of cool cities are reductions in ozone mass and improvements in air quality. In Atlanta, Nashville, and Dallas, urban areas benefiting from reduced smog reach up to 8460, 7350, and 12870 km{sup 2} in area, respectively. Results presented in this paper should be taken as exploratory and preliminary. These will most likely change during a more comprehensive modeling study to be started soon with the support of the US Environmental Protection Agency. The main purpose of the present project was to obtain the initial data (emission inventories) for these regions, simulate meteorological conditions, and perform preliminary sensitivity analysis. In the future, additional regions will be simulated to assess the potential of cool cities in improving urban air quality.

Taha, Haider

1998-06-15T23:59:59.000Z

7

Advancing Residential Retrofits in Atlanta  

SciTech Connect (OSTI)

This report will summarize the home energy improvements performed in the Atlanta, GA area. In total, nine homes were retrofitted with eight of the homes having predicted source energy savings of approximately 30% or greater based on simulated energy consumption.

Jackson, Roderick K [ORNL; Kim, Eyu-Jin [Southface Energy Institute; Roberts, Sydney [Southface Energy Institute; Stephenson, Robert [Southface Energy Institute

2012-07-01T23:59:59.000Z

8

2009 National Electric Transmission Congestion Study- Atlanta Workshop  

Broader source: Energy.gov [DOE]

On July 29, 2008, DOE hosted a regional pre-study workshop in Atlanta, GA to receive input and suggestions concerning the 2009 National Electric Transmission Congestion Study. The agenda andfull...

9

DeKalb County/Metropolitan Atlanta Alternative Fuel and Advanced Technology  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeat Pump Models | Department1 Prepared by:DTEMoab Mill TailingsDATESENERGYDayVehicle

10

DeKalb County/Metropolitan Atlanta Alternative Fuel and Advanced Technology  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeat Pump Models | Department1 Prepared by:DTEMoab Mill

11

DeKalb County/Metropolitan Atlanta Alternative Fuel and Advanced Technology  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-UpHeat Pump Models | Department1 Prepared by:DTEMoab MillVehicle Project | Department of

12

Atlanta, Georgia: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address: 160 EastMaine: Energy Resources JumpAspen Aerogels05. It is640623°Atlanta, GA) Jump to:

13

Atlanta- Sustainable Development Design Standards  

Broader source: Energy.gov [DOE]

In December 2003, the City of Atlanta passed a green building [http://www.atlantaga.gov/modules/showdocument.aspx?documentid=547 ordinance] that applies to city-owned facilities and city-funded...

14

IEEE Energy2030 Atlanta, GA USA  

E-Print Network [OSTI]

Implementation Christophe Guille and George Gross, Fellow, IEEE Abstract ­ The major increases in oil prices

Gross, George

15

Dekalb County Landfi Biomass Facility | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address:011-DNA Jump to:52c8ff988c1 No38e4011f618bDeer Park, Ohio: EnergyDeerfieldDekalb County

16

Better Buildings Challenge, Atlanta Nears Halfway Mark in Meeting...  

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

Challenge Breakout Session Panel with representatives from the City of Atlanta Office of Sustainability, Southface, the U.S. General Services Administration, and two Atlanta BBC...

17

IEEE Energy2030 Atlanta, Georgia, USA  

E-Print Network [OSTI]

(IPS), and can consist of loads, energy sources, and energy storage. The desired result of the proposed architecture is to produce a grid network designed for distributed renewable energy, prevalent energy storageIEEE Energy2030 Atlanta, Georgia, USA 17-18 November 2008 An Architecture for Local Energy

Ratnasamy, Sylvia

18

EECBG Success Story: Atlanta Suburb Greases the Path to Savings...  

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

Atlanta Suburb Greases the Path to Savings with Biodiesel EECBG Success Story: Atlanta Suburb Greases the Path to Savings with Biodiesel December 7, 2011 - 3:33pm Addthis Downtown...

19

E-Print Network 3.0 - atlanta georgia metropolitan Sample Search...  

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

Summary: University; Atlanta, Georgia September 1996 - Assistant Professor of Political Science Emory University... ; Atlanta, Georgia September 1993 - August 1996 On...

20

E-Print Network 3.0 - atlanta urban rain Sample Search Results  

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

(2008). Shem and Shepherd (2009) noted that Atlanta creates enhanced convergence at the rural-urban... delineation of urban convection for Atlanta, Georgia. Int. J. Climatol., 30,...

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

atlanta georgia usa: Topics by E-print Network  

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

values SECURING AMERICA'S FUTURE 12;0 1Georgia Tech Research Institute Annual Report Bennett, Gisele 9 School of Biology Atlanta, Georgia 30332-0230 USA Biology and Medicine...

22

Terahertz absorption in AlGaAs films and detection using heterojunctions  

E-Print Network [OSTI]

a Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA b NDP Optronics, LLC-mail address: uperera@gsu.edu (A.G.U. Perera). 1 Also at NDP Optronics LLC. Infrared Physics & Technology 47

Perera, A. G. Unil

23

Atlanta NAVIGATOR case study. Final report, May 1996--Jun 1997  

SciTech Connect (OSTI)

The Atlanta metropolitan region was the location of one of the most ambitious Intelligent Transportation Systems (ITS) deployments in the United States. This deployment included several individual projects--a Central Transportation Management Center (TMC), six Traffic Control Centers (TCC), one Transit Information Center (TIC), the Travel Information Showcase (TIS), and the extension of the Metropolitan Atlanta Rapid Transit Authority (MARTA) rail network and the new high-occupancy vehicle (HOV) lanes on I-85 and I-75. The Atlanta Centennial Olympic Games and Paralympic Games created a focus for these projects. All of these systems were to be brought on line in time for the Olympic Games. This report presents the findings of the NAVIGATOR Case Study and documents the lessons learned from the Atlanta ITS deployment experience in order to improve other ITS deployments in the future. The Case Study focuses on the institutional, programmatic, and technical issues and opportunities from planning and implementing the ITS deployment in Atlanta. The Case Study collected data and information from interviews, observations, focus groups, and documentation reviews. It presents a series of lessons learned and recommendations for enabling successful ITS deployments nationwide.

Amodei, R.; Bard, E.; Brong, B.; Cahoon, F.; Jasper, K.

1998-11-01T23:59:59.000Z

24

American Society of Engineering Education April 1-2, 2005-Northern Illinois University, DeKalb, Illinois. 2005 IL/IN Sectional Conference.  

E-Print Network [OSTI]

, and the subject of site planning belongs to both of the civil and architectural engineering professions. SometimesAmerican Society of Engineering Education April 1-2, 2005-Northern Illinois University, DeKalb, Illinois. 2005 IL/IN Sectional Conference. Session D-T1-2 OVERLAP BETWEEN MECHANICAL AND CIVIL ENGINEERING

Kostic, Milivoje M.

25

American Society for Engineering Education April 1-2, 2005 Northern Illinois University, DeKalb, Illinois. 2005 IL/IN Sectional Conference  

E-Print Network [OSTI]

Kalb, Illinois. 2005 IL/IN Sectional Conference Session B-T4-1 RENEWABLE ENERGY ALTERNATIVES: CURRENT STATUS ­ Northern Illinois University, DeKalb, Illinois. 2005 IL/IN Sectional Conference of our present energy baseAmerican Society for Engineering Education April 1-2, 2005 ­ Northern Illinois University, De

Kostic, Milivoje M.

26

American Society for Engineering Education April 1-2, 2005 Northern Illinois University, DeKalb, Illinois. 2005 IL/IN Sectional Conference  

E-Print Network [OSTI]

American Society for Engineering Education April 1-2, 2005 ­ Northern Illinois University, DeKalb, Illinois. 2005 IL/IN Sectional Conference Session D-T3-3 INTRODUCING CREATIVITY AND ARTISTIC EXPRESSION INTO ENGINEERING TECHNOLOGY COURSES David P. Devine Indiana University Purdue University Fort Wayne, Fort Wayne

Kostic, Milivoje M.

27

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY ATLANTA FEDERAL CENTER  

E-Print Network [OSTI]

Number 2001-10096 Subject: COE Regulatory Final Environmental Impact Statement (FEIS) for "PCS Phosphate) regulatory Final Environmental Impact Statement (FEIS). This FEIS evaluates the environmental consequencesUNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 4 ATLANTA FEDERAL CENTER 61 FORSYTH STREET

Demers, Nora Egan

28

Clark Atlanta Universities (CAU) Energy Related Research Capabilities |  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-Up fromDepartmentTieCelebrate Earth DayFuelsDepartment of Energy Clark Atlanta

29

E-Print Network 3.0 - atlanta Sample Search Results  

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

Gas Light, Bellsouth, Georgia Power, Atlanta Water, and cable. Updated 102008 ELECTRIC & FIBER Source: Li, Mo - School of Materials Science and Engineering, Georgia...

30

E-Print Network 3.0 - atlanta international airport Sample Search...  

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

international airport Search Powered by Explorit Topic List Advanced Search Sample search results for: atlanta international airport Page: << < 1 2 3 4 5 > >> 1 PLANNING...

31

E-Print Network 3.0 - atlanta metropolitan region Sample Search...  

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

regional group compared... speculative elements surrounding the Atlanta metropolitan area, evidence suggests that local banks... , local and regional community banks continue...

32

Secretary Moniz's Keynote at the Sam Nunn Policy Forum in Atlanta, GA --  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systemsBi (2) Sr (2)ScienceScientistsON THE5,toPlantEnergy

33

Remarks by Federal Blue Ribbon Commission J. David Jameson Atlanta, GA  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -the Mid-Infrared at 278, 298,NIST31 ORV 15051 Modification MOThe Case Federal Blue

34

Building America Case Study: Ground Source Heat Pump Research, TaC Studios Residence, Atlanta, Georigia (Fact Sheet)  

SciTech Connect (OSTI)

As part of the NAHB Research Center Industry Partnership, Southface partnered with TaC Studios, an Atlanta based architecture firm specializing in residential and light commercial design, on the construction of a new test home in Atlanta, GA in the mixed-humid climate. This home serves as a residence and home office for the firm's owners, as well as a demonstration of their design approach to potential and current clients. Southface believes the home demonstrates current best practices for the mixed-humid climate, including a building envelope featuring advanced air sealing details and low density spray foam insulation, glazing that exceeds ENERGY STAR requirements, and a high performance heating and cooling system. Construction quality and execution was a high priority for TaC Studios and was ensured by a third party review process. Post construction testing showed that the project met stated goals for envelope performance, an air infiltration rate of 2.15 ACH50. The homeowner's wished to further validate whole house energy savings through the project's involvement with Building America and this long-term monitoring effort. As a Building America test home, this home was evaluated to detail whole house energy use, end use loads, and the efficiency and operation of the ground source heat pump and associated systems. Given that the home includes many non-typical end use loads including a home office, pool, landscape water feature, and other luxury features not accounted for in Building America modeling tools, these end uses were separately monitored to determine their impact on overall energy consumption.

Not Available

2014-09-01T23:59:59.000Z

35

Community transportation : alternative transportation provision in a low-income neighborhoods in southeast Atlanta  

E-Print Network [OSTI]

Regional transit agencies are ineffective at meeting many of the basic transportation needs of a clustered "Study Area" of low-income Atlanta neighborhoods. For transit dependant residents in the Study Area, getting to the ...

Alexander, James W., 1977-

2004-01-01T23:59:59.000Z

36

DDA, A Water-Soluble DDT Metabolite, for Human Biomonitoring and Wildlife Exposure Surveillance  

E-Print Network [OSTI]

to environmental chemicals. Atlanta, GA: Centers for Diseaseto environmental chemicals. Atlanta, GA: Centers for Disease

Chen, Zhenshan

2011-01-01T23:59:59.000Z

37

The Value of Optimization in Dynamic Ride-Sharing: a Simulation Study in Metro Atlanta  

E-Print Network [OSTI]

of travelers per vehicle trip by effective usage of empty car seats by ride-sharing may of course enhance, and pollution. Moreover, ride-sharing allows users to share car-related expenses such as fuel costs. 1 #12;ByThe Value of Optimization in Dynamic Ride-Sharing: a Simulation Study in Metro Atlanta Niels Agatz

Erera, Alan

38

Black and White Commuting Behavior in a Large Southern City: Evidence from Atlanta  

E-Print Network [OSTI]

Black and White Commuting Behavior in a Large Southern City: Evidence from Atlanta Clark, W. A. VV430X. William A. V. Clark Youqin Huang Black and White Commuting Behavior in a Large Southern City and white households are consistent with the overall hypothesis that households min- imize their commuting

Huang, Youqin

39

Atlanta Centennial Olympic Games and Paralympic Games event study, 1996. Final report, July 1996--August 1996  

SciTech Connect (OSTI)

The Atlanta metropolitan region was the location of one of the most ambitious Intelligent Transportation Systems (ITS) deployments in the United States. This deployment included several individual projects--a Central Transportation Management Center (TMC), six Traffic Control Centers (TCCs), one Transit Information Center (TIC), The Travel Information Showcase (TIS), and the extension of the Metropolitan Atlanta Rapid Transit Authority (MARTA) Rail network and the new high-occupancy vehicle (HOV) lanes on I-85 and I-75. The 1996 Atlanta Centennial Olympic Games and Paralympic Games created a focus for these projects. All of these systems were to be brought on-line in time for the Olympic Games. This report presents the findings of the 1996 Olympic and Paralympic Games Events Study--a compilation of findings of system performance, the benefits realized, and the lessons learned during their operations over the event period. The study assessed the performance of the various Travel Demand Management (TDM) plans employed for Olympic Games traffic management.

Amodei, R.; Bard, E.; Brong, B.; Cahoon, F.; Jasper, K.

1998-11-01T23:59:59.000Z

40

Summary of Needs and Opportunities from the 2011 Residential Energy Efficiency Stakeholders Meeting: Atlanta, Georgia -- March 16-18, 2011  

SciTech Connect (OSTI)

This summary report outlines needs and issues for increasing energy efficiency of new and existing U.S homes, as identified at the U.S Department of Energy Building America program Spring 2011 stakeholder meeting in Atlanta, Georgia.

Not Available

2011-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Synthesis and properties of green phosphor SrGa2S4:Eu2 emission displays by an environmentally clean technique  

E-Print Network [OSTI]

by an environmentally clean technique Y.D. Jianga , G. Villalobosa , J.C. Souriaua , H. Parisa , C.J. Summersa , Z.L. Wangb,* a Phosphor Technology Center of Excellence, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA b School of Materials Science and Engineering, Georgia

Wang, Zhong L.

42

Capacitance hysteresis in GaN/AlGaN heterostructures L. E. Byrum,1  

E-Print Network [OSTI]

Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303, USA 2 NDP Optronics

Matsik, Steven G.

43

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

E-Print Network [OSTI]

, Georgia State University, Atlanta, Georgia 30303 S. G. Matsik NDP Optronics LLC, Mableton, Georgia 30126 A

Perera, A. G. Unil

44

Atlanta Survey  

Annual Energy Outlook 2013 [U.S. Energy Information Administration (EIA)]

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) " ,"ClickPipelines AboutDecemberSteam Coal Import CostsLiquidsYearReserves (Billion5: Oil and Gas

45

COOPERATIVE AND NON-COOPERATIVE DECISION BEHAVIORS IN RESPONSE TO THE INSPECTION AND MAINTENANCE PROGRAM IN THE ATLANTA  

E-Print Network [OSTI]

COOPERATIVE AND NON-COOPERATIVE DECISION BEHAVIORS IN RESPONSE TO THE INSPECTION AND MAINTENANCE BEHAVIORS IN RESPONSE TO THE INSPECTION AND MAINTENANCE PROGRAM IN THE ATLANTA AIRSHED, 1997-2001 Bryan G not have been able to cover the immense research landscape that is presented in this dissertation. Bryan

Vermont, University of

46

Thermal comfort in naturally-ventilated and air-conditioned classrooms in the tropics.  

E-Print Network [OSTI]

in kindergartens. IAQ '91 Healthy Buildings, Atlanta, GA,kindergartens. in IAQ '91 Healthy Buildings. 1991. Atlanta,in kindergartens. IAQ '91 Healthy Buildings, Atlanta, GA,

Kwok, Alison G

1997-01-01T23:59:59.000Z

47

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

E-Print Network [OSTI]

, Georgia State University, Atlanta, Georgia 30303, USA; bNDP Optronics LLC, Mableton, Georgia 30126, USA; c

Dietz, Nikolaus

48

Strategic Utilization of Paper/Wood Waste for Biodiesel Fuel Art J. Ragauskas, Institute of Paper Science and Technology; Georgia Institute of Technology, Atlanta, GA.  

E-Print Network [OSTI]

Strategic Utilization of Paper/Wood Waste for Biodiesel Fuel Art J. Ragauskas, Institute of Paper lignocellulosics to biodiesel fuel Feedstocks ABSTRACT This poster examines the potential of utilizing waste paper CelluloseHemicelluloseLigninResource Cracking and Refining of Polysaccharides Bio-Diesel Substitutes

49

Performance improvements of ultraviolet/infrared dual-band detectors A.G.U. Perera a,*, G. Ariyawansa a  

E-Print Network [OSTI]

University, Atlanta, GA 30303, United States b NDP Optronics, Mableton, GA 30126, United States c School

Dietz, Nikolaus

50

Ga nanoparticle-enhanced photoluminescence of GaAs  

SciTech Connect (OSTI)

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.

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

51

AlGaN/GaN-based power semiconductor switches  

E-Print Network [OSTI]

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 ...

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

2013-01-01T23:59:59.000Z

52

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

SciTech Connect (OSTI)

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.

Mreke, 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

53

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

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

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

54

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

SciTech Connect (OSTI)

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.

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

55

GaN/AlGaN ultraviolet/infrared dual-band detector G. Ariyawansa, M. B. M. Rinzan, M. Alevli, M. Strassburg, N. Dietz, and A. G. U. Pereraa  

E-Print Network [OSTI]

, Atlanta, Georgia 30303 S. G. Matsik NDP Optronics, Mableton, Georgia 30126 A. Asghar and I. T. Ferguson

Perera, A. G. Unil

56

Characterisation of Ga-coated and Ga-brazed aluminium  

SciTech Connect (OSTI)

This work is devoted to the brazing of aluminium using liquid gallium. Gallium was deposited on aluminium samples at {approx} 50 Degree-Sign C using a liquid gallium 'polishing' technique. Brazing was undertaken for 30 min at 500 Degree-Sign C in air. EDS (Energy Dispersive X-ray Spectroscopy) and AES (Auger Electron Spectroscopy) characterisation of Ga-coated samples has shown that the Ga surface layer thickness is of ten (or a few tens of) nanometres. Furthermore, aluminium oxide layer (Al{sub 2}O{sub 3}) was shown to be 'descaled' during Ga deposition, which ensures good conditions for further brazing. Cross-section examination of Ga-coated samples shows that liquid gallium penetrates into the aluminium grain boundaries during deposition. The thickness of the grain boundary gallium film was measured using an original EDS technique and is found to be of a few tens of nanometres. The depth of gallium grain boundary penetration is about 300 {mu}m at the deposition temperature. The fracture stress of the brazed joints was measured from tensile tests and was determined to be 33 MPa. Cross-section examination of brazed joints shows that gallium has fully dissolved into the bulk and that the joint is really autogenous. - Highlights: Black-Right-Pointing-Pointer Aluminium can be brazed using liquid gallium deposited by a 'polishing' technique. Black-Right-Pointing-Pointer The aluminium oxide layer is 'descaled' during liquid Ga 'polishing' deposition. Black-Right-Pointing-Pointer EDS can be used for determination of surface and grain boundary Ga film thickness. Black-Right-Pointing-Pointer The surface and grain boundary Ga film thickness is of a few tens of nm. Black-Right-Pointing-Pointer Surface and grain boundary gallium dissolves in the bulk during brazing.

Ferchaud, E. [Universite de Nantes, Polytech'Nantes, Laboratoire Genie des Materiaux et Procedes Associes, Rue Christian Pauc, 44306 Nantes Cedex 3 (France); Christien, F., E-mail: frederic.christien@univ-nantes.fr [Universite de Nantes, Polytech'Nantes, Laboratoire Genie des Materiaux et Procedes Associes, Rue Christian Pauc, 44306 Nantes Cedex 3 (France); Barnier, V. [Ecole Nationale Superieure des Mines, MPI, CNRS UMR5146, Centre SMS, 158 Cours Fauriel, 42023 Saint Etienne (France); Paillard, P. [Universite de Nantes, Polytech'Nantes, Laboratoire Genie des Materiaux et Procedes Associes, Rue Christian Pauc, 44306 Nantes Cedex 3 (France)

2012-05-15T23:59:59.000Z

57

Intense terahertz emission from molecular beam epitaxy-grown GaAs/GaSb(001)  

SciTech Connect (OSTI)

Intense terahertz (THz) electromagnetic wave emission was observed in undoped GaAs thin films deposited on (100) n-GaSb substrates via molecular beam epitaxy. GaAs/n-GaSb heterostructures were found to be viable THz sources having signal amplitude 75% that of bulk p-InAs. The GaAs films were grown by interruption method during the growth initiation and using various metamorphic buffer layers. Reciprocal space maps revealed that the GaAs epilayers are tensile relaxed. Defects at the i-GaAs/n-GaSb interface were confirmed by scanning electron microscope images. Band calculations were performed to infer the depletion region and electric field at the i-GaAs/n-GaSb and the air-GaAs interfaces. However, the resulting band calculations were found to be insufficient to explain the THz emission. The enhanced THz emission is currently attributed to a piezoelectric field induced by incoherent strain and defects.

Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel [National Institute of Physics, University of the Philippines Diliman, Quezon City 1101 (Philippines); Que, Christopher T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila 1004 (Philippines); Yamamoto, Kohji; Tani, Masahiko [Research Center for Development of Far-Infrared Region, University of Fukui, Fukui 910-8507 (Japan)

2012-12-15T23:59:59.000Z

58

GA Solar | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDIT REPORTOpen EnergyBoard" form. To create aGA SNC Solar Jump to:GA-Solar

59

Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells  

E-Print Network [OSTI]

Plasmonic nanoparticle enhanced photocurrent in GaN/InGaN/GaN quantum well solar cells Imogen M of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA 2 Semiconductor Nanoscience Institute, California Institute of Technology, Pasadena, California 91125, USA Received 26

Atwater, Harry

60

Native point defects in GaSb  

SciTech Connect (OSTI)

We have applied positron annihilation spectroscopy to study native point defects in Te-doped n-type and nominally undoped p-type GaSb single crystals. The results show that the dominant vacancy defect trapping positrons in bulk GaSb is the gallium monovacancy. The temperature dependence of the average positron lifetime in both p- and n-type GaSb indicates that negative ion type defects with no associated open volume compete with the Ga vacancies. Based on comparison with theoretical predictions, these negative ions are identified as Ga antisites. The concentrations of these negatively charged defects exceed the Ga vacancy concentrations nearly by an order of magnitude. We conclude that the Ga antisite is the native defect responsible for p-type conductivity in GaSb single crystals.

Kujala, J.; Segercrantz, N.; Tuomisto, F.; Slotte, J. [Department of Applied Physics, Aalto University School of Science, P.O. Box 14100, FI-00076 AALTO (Finland)

2014-10-14T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

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

SciTech Connect (OSTI)

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.

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

62

Beta decay of Ga-62  

E-Print Network [OSTI]

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...

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

63

3/5/09 11:36 AMTech composes the music of fish | ajc.com Page 1 of 3http://www.ajc.com/metro/content/metro/atlanta/stories/2009/02/22/tech_music_fish.html  

E-Print Network [OSTI]

3/5/09 11:36 AMTech composes the music of fish | ajc.com Page 1 of 3http://www.ajc.com/metro/content/metro/atlanta/stories/2009/02/22/tech_music_fish.html Enlarge this image CURTIS COMPTON / ccompton@ajc.com Dr. Bruce Walker (right), project lead, and researcher Carrie Bruce watch fish during work on a Center for Music

64

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

SciTech Connect (OSTI)

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.

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

65

InGaAsN/GaAs heterojunction for multi-junction solar cells  

DOE Patents [OSTI]

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%.

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

66

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

SciTech Connect (OSTI)

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.

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

67

Impact of electrochemical process on the degradation mechanisms of AlGaN/GaN HEMTs  

E-Print Network [OSTI]

AlGaN/GaN high electron mobility transistors (HEMTs) constitute a new generation of transistors with excellent electrical characteristics and great potential to replace silicon technology in the future, especially in high ...

Gao, Feng, Ph. D. Massachusetts Institute of Technology

2014-01-01T23:59:59.000Z

68

Spontaneous emission in GaN/InGaN photonic crystal nanopillars  

E-Print Network [OSTI]

. 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

Boyer, Edmond

69

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

SciTech Connect (OSTI)

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%.

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

70

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

SciTech Connect (OSTI)

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.

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

71

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

E-Print Network [OSTI]

focused on the demonstration of ultraviolet UV optoelectronic devices. Such devices hold promise, material related problems complicate the growth of such optoelectronic devices oper- ating at short wavelengths. With the use of InGaN/GaN quantum structures, optoelectronic devices operating in vis- ible

Demir, Hilmi Volkan

72

Structural and optical properties of InGaNGaN nanowire heterostructures grown by molecular beam epitaxy  

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

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.

Limbach, F. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jlich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Gotschke, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jlich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Stoica, T. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jlich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany); Calarco, R. [Institute of Bio- and Nanosystems (IBN-1), Research Centre Jlich 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 Jlich GmbH and JARA-FIT Fundamentals of Future Information Technology (Germany)

2011-01-07T23:59:59.000Z

73

Ohmic contacts to n-GaSb  

E-Print Network [OSTI]

in the semiconductor is measured during the deposition of the metal contact. In using method 1, the I-V characteristics is plotted. The thermionic emission theory predicts the current-voltage characteristics of Schottky diodes as [13]: J(rhcrmionic) = A" T' exp... of different work functions. This situation is also true for metal contacts to n-GaSb. Polyakov et al. [14] examined the Schottky diodes of Al, Au, In, Pd, Ga, and Sb on Te doped n-GaSb. They used the C-V measurements methods. They reported that barrier...

Yang, Zhengchong

2012-06-07T23:59:59.000Z

74

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

SciTech Connect (OSTI)

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.

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

75

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

SciTech Connect (OSTI)

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.

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

76

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

SciTech Connect (OSTI)

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.

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

77

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

SciTech Connect (OSTI)

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.

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

78

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

SciTech Connect (OSTI)

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.

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

79

DeKalb County, Alabama: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address:011-DNA Jump to:52c8ff988c1 No38e4011f618b No revisionDeFrees Flume 2 Jump

80

DeKalb County, Illinois: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address:011-DNA Jump to:52c8ff988c1 No38e4011f618b No revisionDeFrees Flume 2 JumpDeKalb County,

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81

DeKalb County, Indiana: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address:011-DNA Jump to:52c8ff988c1 No38e4011f618b No revisionDeFrees Flume 2 JumpDeKalb County,US

82

DeKalb County, Missouri: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address:011-DNA Jump to:52c8ff988c1 No38e4011f618b No revisionDeFrees Flume 2 JumpDeKalb

83

DeKalb County, Tennessee: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address:011-DNA Jump to:52c8ff988c1 No38e4011f618b No revisionDeFrees Flume 2 JumpDeKalbTennessee.

84

DeKalb County, Georgia: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision has beenFfe2fb55-352f-473b-a2dd-50ae8b27f0a6 No revision has been approved forDayton is aCounty, Georgia:

85

Lee-Dekalb Wind Energy Center | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision hasInformation Earth's Heat JumpInc Place:Keystone CleanLaton,Learn Gapminder Jump3. It isLee

86

Electron Transport in a Two-Dimensional Electron Gas at GaAs/AlGaAs Heterointerface  

E-Print Network [OSTI]

in condensed matters. Two-dimensional electron gas (2DEG) at the GaAs/AlGaAs hetero-interface o ersThesis Electron Transport in a Two-Dimensional Electron Gas at GaAs/AlGaAs Heterointerface under of the art samples, the mean free path of electrons exceeds 10;4 m at low temperature. The achievement

Katsumoto, Shingo

87

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

E-Print Network [OSTI]

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

Woodall, Jerry M.

88

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

E-Print Network [OSTI]

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

Wetzel, Christian M.

89

GaTe semiconductor for radiation detection  

DOE Patents [OSTI]

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.

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

2009-06-23T23:59:59.000Z

90

Accepted with minor revisions by TNNLS Special Issue on Learning in Nonstationary and Evolving Environments  

E-Print Network [OSTI]

of Technology, Atlanta, GA 30332­0250 2Entergy Services, Inc., New Orleans, LA 70053 3Howard University, NW

Ji, Chuanyi

91

Review of Technologies for Low-Cost Integrated Amin Rida, Vasileios Lakafosis, Rushi Vyas, and  

E-Print Network [OSTI]

Atlanta, GA 30324 USA arida@ece.gatech.edu Symeon (Simos) Nikolaou Frederick Research Center Nicosia, 1036

Tentzeris, Manos

92

Low Cost Inkjet-printing Paper-Based Modules for RFID Sensing and Wireless Applications  

E-Print Network [OSTI]

of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0250, USA 1 arida

Tentzeris, Manos

93

Development and Implementation of Novel UHF Paper-Based RFID Designs for Anti-counterfeiting and Security Applications  

E-Print Network [OSTI]

Institute of Technology, Atlanta, GA 30332-0250, USA *E-mail:arida@ece.gatech.edu I. INTRODUCTION Radio

Tentzeris, Manos

94

1080 IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, VOL. 9, 2010 Integrated Wideband 2-D and 3-D Transitions  

E-Print Network [OSTI]

are with the Electrical Engineering Department, Georgia Institute of Technology, Atlanta, GA 30332 USA (e-mail: arida

Tentzeris, Manos

95

Phthalates and Male Reproductive Health: Estimation of Daily Intake Doses in Pregnant Womenfrom an Epidemiologic Study  

E-Print Network [OSTI]

environmental chemicals in the developmental basis of reproductive disease andto Environmental Chemicals. Atlanta, GA:Centers for Disease

Marsee, Kevin E

2007-01-01T23:59:59.000Z

96

Choice Based Revenue Management for Parallel Flights  

E-Print Network [OSTI]

Mar 6, 2014 ... We formulate corresponding deterministic (fluid) optimization ... and Systems Engineering, Georgia Institute of Technology, Atlanta, GA...

Jim Dai

2014-03-06T23:59:59.000Z

97

Report  

E-Print Network [OSTI]

Advanced Analytics Manager, UPS, 30328 Atlanta, GA, USA, foresomenteneikona@gmail.com. Tao Wu. Advanced Analytics Department, Dow Chemical, 48642...

2015-02-04T23:59:59.000Z

98

Near-surface depletion of antimony during the growth of GaAsSb and GaAs/GaAsSb nanowires  

SciTech Connect (OSTI)

The near-surface reduction of the Sb mole fraction during the growth of GaAsSb nanowires (NWs) and GaAs NWs with GaAsSb inserts has been studied using quantitative high-angle annular dark field scanning transmission electron microscopy (STEM). A model for diffusion of Sb in the hexagonal NWs was developed and employed in combination with the quantitative STEM analysis. GaAsSb NWs grown by Ga-assisted molecular beam epitaxy (MBE) and GaAs/GaAsSb NWs grown by Ga- and Au-assisted MBE were investigated. At the high temperatures employed in the NW growth, As-Sb exchange at and outward diffusion of Sb towards the surface take place, resulting in reduction of the Sb concentration at and near the surface in the GaAsSb NWs and the GaAsSb inserts. In GaAsSb NWs, an increasing near-surface depletion of Sb was observed towards the bottom of the NW due to longer exposure to the As beam flux. In GaAsSb inserts, an increasing change in the Sb concentration profile was observed with increasing post-insert axial GaAs growth time, resulting from a combined effect of radial GaAs overgrowth and diffusion of Sb. The effect of growth temperature on the diffusion of Sb in the GaAsSb inserts was identified. The consequences of these findings for growth optimization and the optoelectronic properties of GaAsSb are discussed.

Kauko, H.; Helvoort, A. T. J. van, E-mail: a.helvoort@ntnu.no [Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim (Norway); Fimland, B. O.; Munshi, A. M. [Department of Electronics and Telecommunications, NTNU, Trondheim (Norway); Grieb, T.; Mller, K.; Rosenauer, A. [Institut fr Festkrperphysik, Universitt Bremen, Bremen (Germany)

2014-10-14T23:59:59.000Z

99

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

SciTech Connect (OSTI)

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.

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

100

REGULAR PAPER Improvement of Surge Protection by Using an AlGaN/GaN-Based  

E-Print Network [OSTI]

the metal oxide varistor (MOV) and resistor (R) in a state-of-the-art surge protection circuit), metal oxide varistor (MOV), and transient voltage suppressor (TVS) diodes are the state-of-the- artREGULAR PAPER Improvement of Surge Protection by Using an AlGaN/GaN-Based Metal­Semiconductor­Metal

Chow, Lee

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Lattice-matched epitaxial GaInAsSb/GaSb thermophotovoltaic devices  

SciTech Connect (OSTI)

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.

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

102

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

SciTech Connect (OSTI)

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 nanodisks 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}=1.310.15 eV, a diffusivity prefactor of D{sub 0}?=?0.53(2.11) 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 adatoms on IIIV crystal surfaces and the fabrication of designable nanostructures.

Bietti, Sergio, E-mail: sergio.bietti@mater.unimib.it; Somaschini, Claudio; Esposito, Luca; Sanguinetti, Stefano [LNESS and Dipartimento di Scienza dei Materiali, Universit di Milano Bicocca, Via Cozzi 55, I20125 Milano (Italy); Fedorov, Alexey [LNESS and CNRIFN, via Anzani 42, I-22100 Como (Italy)

2014-09-21T23:59:59.000Z

103

Study and development of tunable, single mode AlGaAs/GaAs lasers  

SciTech Connect (OSTI)

Liquid phase epitaxy has been employed in this study to fabricate two-section wavelength tunable lasers. GaAs/AlGaAs and In GaAsP/InP material system have been used for fabricating the lasers. Both direct (butt) coupling and evanescent coupling approaches have been studied. The complications associated with the regrowth process have been responsible for poor laser performance. Some DBR gratings for three-section lasers have been made using the electron beam lithography at UCSD. A simple set up has been tested to measure the wavelength shift of GaAs/AlGaAs lasers. Also, a simple structure which avoids the regrowth process has been proposed for the two-section laser. 9 refs., 14 figs.

Yu, P.K.L.; Liu, J.C. (California Univ., San Diego, La Jolla, CA (USA). Dept. of Electrical and Computer Engineering)

1990-09-01T23:59:59.000Z

104

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

SciTech Connect (OSTI)

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.

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

105

Quantum confinement in GaP nanoclusters  

SciTech Connect (OSTI)

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.

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

1994-06-01T23:59:59.000Z

106

Defect studies in low-temperature-grown GaAs  

SciTech Connect (OSTI)

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.

Bliss, D.E.

1992-11-01T23:59:59.000Z

107

Defect studies in low-temperature-grown GaAs  

SciTech Connect (OSTI)

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.

Bliss, D.E.

1992-11-01T23:59:59.000Z

108

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

SciTech Connect (OSTI)

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.

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

109

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

SciTech Connect (OSTI)

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.

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. [Universit Europenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Cosmes, 35708 Rennes (France)] [Universit Europenne de Bretagne, INSA Rennes, France and CNRS, UMR 6082 Foton, 20 Avenue des Buttes de Cosmes, 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 Fsica, Universidade Federal do Cear, P.O. Box 6030, FortalezaCE, 60455-970 (Brazil); Alonso, M. I. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain)] [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); Goi, A. R. [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain) [ICMAB-CSIC, Campus UAB, 08193 Bellaterra (Spain); ICREA, Passeig Llus Companys 23, 08010 Barcelona (Spain); Turban, P. [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Universit de Rennes 1, F-35042 Rennes Cedex (France)] [Equipe de Physique des Surfaces et Interfaces, Institut de Physique de Rennes UMR UR1-CNRS 6251, Universit de Rennes 1, F-35042 Rennes Cedex (France)

2014-01-06T23:59:59.000Z

110

Nucleation and Growth of GaN on GaAs (001) Substrates  

SciTech Connect (OSTI)

The nucleation of GaN thin films on GaAs is investigated for growth at 620 "C. An rf plasma cell is used to generate chemically active nitrogen from N2. An arsenic flux is used in the first eight monolayer of nitride growth to enhance nucleation of the cubic phase. Subsequent growth does not require an As flux to preserve the cubic phase. The nucleation of smooth interfaces and GaN films with low stacking fault densities is dependent upon relative concentrations of active nitrogen species in the plasma and on the nitrogen to gallium flux ratio.

Drummond, Timothy J.; Hafich, Michael J.; Heller, Edwin J.; Lee, Stephen R.; Liliental-Weber, Zuzanna; Ruvimov, Sergei; Sullivan, John P.

1999-05-03T23:59:59.000Z

111

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

SciTech Connect (OSTI)

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.

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

112

On strongly GA-convex functions and stochastic processes  

SciTech Connect (OSTI)

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.

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

2014-08-20T23:59:59.000Z

113

Energy absorption in Ni-Mn-Ga/ polymer composites  

E-Print Network [OSTI]

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 ...

Feuchtwanger, Jorge

2006-01-01T23:59:59.000Z

114

Accurate characterization and improvement of GaAs microstrip attenuation  

E-Print Network [OSTI]

Convergence. III. E. 6 Final Model. III. F Simulation Results for 100 um GaAs. . III. F. 1 On-GaAs Microstrip. III. I', 2 Suspended Microstrip Line . . . . 50 . . . . 51 . . . . 54 . . . . 56 . . . . 56 . . . 56 . . . . 64 64 . . . , 64 III. F. 3... Comparison Between On-GaAs and Suspcndcd Microstrip . . . 68 III. F. 4 Microstrip Inductance III. G EM Parameters in CAD Simulations . . III. H Simulation Results for 150 um GaAs. III. I Conclusions and Recommendations. IV RESEARCH ACCOMPLISHMENTS...

Carroll, James Mason

2012-06-07T23:59:59.000Z

115

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

SciTech Connect (OSTI)

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.

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

116

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

SciTech Connect (OSTI)

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.

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

117

Multiband GaNAsP Quaternary Alloys  

SciTech Connect (OSTI)

We have synthesized GaN{sub x}As{sub 1-y}P{sub y} alloys (x {approx} 0.3-1% and y = 0-0.4) using nitrogen N ion implantation into GaAsP epilayers followed by pulsed laser melting and rapid thermal annealing techniques. As predicted by the band anticrossing model, the incorporation of N splits the conduction band (E{sub M}) of the GaAs{sub 1-y}P{sub y} substrate, and strong optical transitions from the valence band to the lower (E{sub -}) and upper (E{sub +}) conduction subbands are observed. The relative strengths of the E{sub -} and E{sub +} transition change as the localized N level E{sub N} emerges from the conduction band forming narrow intermediate band for y > 0.3. The results show that GaN{sub x}As{sub 1-x-y}P{sub y} alloys with y > 0.3 is a three band semiconductor alloy with potential applications for high-efficiency intermediate band solar cells.

Yu, K.M.; Walukiewicz, W.; Ager III, J.W.; Bour, D.; Farshchi,R.; Dubon, O.D.; Li, S.X.; Sharp, I.D.; Haller, E.E.

2005-12-08T23:59:59.000Z

118

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

E-Print Network [OSTI]

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

McKittrick, Joanna

119

AlGaAs/GaAs photovoltaic converters for high power narrowband radiation  

SciTech Connect (OSTI)

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.

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

120

Recent progress in InGaAsSb/GaSb TPV devices  

SciTech Connect (OSTI)

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.

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

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Radio-frequency reflectometry on an undoped AlGaAs/GaAs single electron transistor  

SciTech Connect (OSTI)

Radio frequency reflectometry is demonstrated in a sub-micron undoped AlGaAs/GaAs device. Undoped single electron transistors (SETs) are attractive candidates to study single electron phenomena, due to their charge stability and robust electronic properties after thermal cycling. However, these devices require a large top-gate, which is unsuitable for the fast and sensitive radio frequency reflectometry technique. Here, we demonstrate that rf reflectometry is possible in an undoped SET.

MacLeod, S. J.; See, A. M.; Keane, Z. K.; Scriven, P.; Micolich, A. P.; Hamilton, A. R., E-mail: Alex.Hamilton@unsw.edu.au [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Aagesen, M.; Lindelof, P. E. [Nanoscience Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)] [Nanoscience Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen (Denmark)

2014-01-06T23:59:59.000Z

122

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

SciTech Connect (OSTI)

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.

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

2006-01-01T23:59:59.000Z

123

Point defect balance in epitaxial GaSb  

SciTech Connect (OSTI)

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 ptype conductivity is caused by different defects in GaSb grown with different methods.

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 Gteborg (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

124

Reactive codoping of GaAlInP compound semiconductors  

DOE Patents [OSTI]

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.

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

2008-02-12T23:59:59.000Z

125

Nano-scale characterization of GaAsP/GaAs strained superlattice structure by nano-beam electron diffraction  

SciTech Connect (OSTI)

Distribution of lattice strain in a GaAsP/GaAs superlattice with a periodicity of 10?nm thickness, deposited on a 100?nm GaAs basal layer has been measured by nano-beam electron diffraction. The superlattice on the (001) plane of the basal GaAs layer shows a constant lattice strain from the bottom to the top layers, whereas the superlattice on the basal GaAs surface sloped by 16 from the (001) plane shows a variation of the lattice strain and crystal orientation. The difference of the strain distributions was discussed from the viewpoint of average strain. This tilt was explained by an atomistic model.

Jin, Xiuguang [Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Nakahara, Hirotaka [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Saitoh, Koh; Tanaka, Nobuo [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Takeda, Yoshikazu [Nagoya Industrial Science Research Institute, Nagoya 464-0819 (Japan); Aichi Synchrotron Radiation Center, Aichi Science and Technology Foundation, Seto 489-0965 (Japan)

2014-03-17T23:59:59.000Z

126

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

SciTech Connect (OSTI)

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.

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

2014-03-21T23:59:59.000Z

127

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

SciTech Connect (OSTI)

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.

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

2006-01-01T23:59:59.000Z

128

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

SciTech Connect (OSTI)

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.

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

129

Efficiency enhancement of InGaN/GaN solar cells with nanostructures  

SciTech Connect (OSTI)

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%.

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

130

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

SciTech Connect (OSTI)

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 IV 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.

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

131

Direct observation of Ga-rich microdomains in crack-free AlGaN grown on patterned GaNsapphire substrates  

E-Print Network [OSTI]

.e., a homogeneous aluminum content, is found near the sample surface. However, the strong rise of quantum efficiency for AlGaN because the Al alloys also nucleate on the mask materials. Recently, growth on patterned structured into a periodic grid of trenches and terraces along 1100 . Prior to the final AlGaN ( Al 0

Nabben, Reinhard

132

Auditory Menus Are Not Just Spoken Visual Menus: A Case Study of  

E-Print Network [OSTI]

Interface Copyright is held by the author/owner(s). CHI 2010, April 10­15, 2010, Atlanta, Georgia, USA. ACM Institute of Technology 654 Cherry Street, Atlanta, GA, 30332 USA davison@gatech.edu Bruce N. Walker Street, Atlanta, GA, 30332 USA bruce.walker@psych.gatech.edu CHI 2010: Work-in-Progress (Spotlight

133

GaAs single quantum dot embedded into AlGaAs nanowire  

SciTech Connect (OSTI)

We report on a study of the photoluminescence spectra taken from quasi one-dimensional and quasi zero-dimensional semiconductor heterostructures. The structures were grown by molecular-beam epitaxy in (111) direction and were cylindrical nanowires based on AlGaAs, of 20 - 50 nm in diameter and 0.5 - 1 ?m in length. Inside the nanowires contain one or two GaAs quantum dots, of 2 nm thick and 15 - 45 nm in diameter. We studied a single nanowire. The photoluminescence and photoluminescence excitation spectra were registered as a function of the intensity of optical excitation.

Kochereshko, V. P.; Kats, V. N. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg, Russia and Spin Optics Laboratory, Saint Petersburg State University, Ul'yanovskaya 1, Petrodvorets, St. Petersburg, 198904 (Russian Federation); Platonov, A. V. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg (Russian Federation); Cirlin, G. E.; Bouravleuv, A. D.; Samsonenko, Yu. B. [A.F.Ioffe Physical-Technical Institute, Politekhnicheskaya 26, 194021, St. Petersburg, Russia and St. Petersburg Academic University of the RAS Khlopina 8/3, 195220, St. Petersburg (Russian Federation); Besombes, L.; Mariette, H. [CEA-CNRS group Nanophysique et Semiconducteurs, CEA, INAC, SP2M, and Institut Nel, 17 rue des Martyrs, F-38054 Grenoble (France)

2013-12-04T23:59:59.000Z

134

Wavelength limits for InGaN quantum wells on GaN  

SciTech Connect (OSTI)

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.

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

135

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

SciTech Connect (OSTI)

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.

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

136

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

SciTech Connect (OSTI)

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.

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

137

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

SciTech Connect (OSTI)

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.

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

138

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

SciTech Connect (OSTI)

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.

Braun, T.; Schneider, C.; Maier, S.; Forchel, A.; Hfling, S.; Kamp, M. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Rntgen-Research Center for Complex Material Systems, Universitt Wrzburg, Am Hubland, D-97074, Wrzburg (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

139

AlGaAs/GaAs quantum well infrared detectors and modulators  

E-Print Network [OSTI]

to the quantum well. This optical transition wavelength lies in the mid infrared region of the spectrum. To get a more realistic picture of the optical transition in a 1-D quantum well, the non-parabolicity of the conduction band of GaAs is taken... into consideration. Further it is seen that with the change in temperature and doping concentration the width and peak of the absorption curve also changes. Based on the above calculations and results an AIGaAs/GaAs quantum well infrared photodetector...

Dave, Digant Praful

1990-01-01T23:59:59.000Z

140

Radiation Hard AlGaN Detectors and Imager  

SciTech Connect (OSTI)

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.

None

2012-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Nitrogen-concentration control in GaNAs/AlGaAs quantum wells using nitrogen ?-doping technique  

SciTech Connect (OSTI)

GaNAs/Al{sub 0.35}Ga{sub 0.65}As multiple quantum wells (MQWs) with nitrogen ?-doping were fabricated on GaAs (100) substrates by plasma-assisted molecular beam epitaxy. High controllability of nitrogen-concentrations in the MQWs was achieved by tuning nitrogen ?-doping time. The maximum nitrogen concentration in the MQWs was 2.8%. The MQWs exhibit intense, narrow photoluminescence emission.

Mano, Takaaki; Jo, Masafumi; Kuroda, Takashi; Noda, Takeshi; Sugimoto, Yoshimasa; Sakuma, Yoshiki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Elborg, Martin; Sakoda, Kazuaki [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan and Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)

2014-05-15T23:59:59.000Z

142

GaAs/AlGaAs nanostructured composites for free-space and integrated optical devices  

E-Print Network [OSTI]

after development with MIBK:IPA=1:2 for 2min. Different fillon GaAs developed with MIBK:IPA=1:2 for (a) 1 min; (b) 2d) shows a nonoptimized developer, MIBK:IPA=2:1, used for 3

Tsai, Chia-Ho

2006-01-01T23:59:59.000Z

143

O?[]O? nuclear ?-decay of ?Ga  

E-Print Network [OSTI]

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...

Hyman, Bruce Carl

1999-01-01T23:59:59.000Z

144

General Atomics (GA) | Princeton Plasma Physics Lab  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary)morphinanInformation Desert Southwest Region service area. TheEPSCIResearch to sponsorGeneral Atomics (GA)

145

GA SNC Solar | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDIT REPORTOpen EnergyBoard" form. To create aGA SNC Solar Jump to:

146

Theoretical studies of optical gain tuning by hydrostatic pressure in GaInNAs/GaAs quantum wells  

SciTech Connect (OSTI)

In order to describe theoretically the tuning of the optical gain by hydrostatic pressure in GaInNAs/GaAs quantum wells (QWs), the optical gain calculations within kp approach were developed and applied for N-containing and N-free QWs. The electronic band structure and the optical gain for GaInNAs/GaAs QW were calculated within the 10-band kp model which takes into account the interaction of electron levels in the QW with the nitrogen resonant level in GaInNAs. It has been shown that this interaction increases with the hydrostatic pressure and as a result the optical gain for GaInNAs/GaAs QW decreases by about 40% and 80% for transverse electric and transverse magnetic modes, respectively, for the hydrostatic pressure change from 0 to 40 kilobars. Such an effect is not observed for N-free QWs where the dispersion of electron and hole energies remains unchanged with the hydrostatic pressure. This is due to the fact that the conduction and valence band potentials in GaInAs/GaAs QW scale linearly with the hydrostatic pressure.

Gladysiewicz, M.; Wartak, M. S. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw, Wybrzeze Wyspianskiego 27 (Poland); Department of Physics and Computer Science, Wilfrid Laurier University, Waterloo, Ontario N2L 3C5 (Canada); Kudrawiec, R. [Institute of Physics, Wroclaw University of Technology, 50-370 Wroclaw, Wybrzeze Wyspianskiego 27 (Poland)

2014-01-21T23:59:59.000Z

147

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]

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

Shepelyansky, Dima

148

Development of a Bulk GaN Growth Technique for Low Defect Density...  

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

current due to bulk defects GaN is Grown Heteroepitaxially on Sapphire (and Silicon Carbide) Substrates * As grown GaN nucleation layers contain disordered GaN with many...

149

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

SciTech Connect (OSTI)

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.

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.; zgr, .; Morko, 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

150

The Essentials for GA Water Planning The Relationship  

E-Print Network [OSTI]

" FL Water Law Regulated Riparianism "Heavy" Admin Water Law ? #12;Comprehensive Water Resource Study Supply a. Water Allocation ­ Withdrawal Permit Program b. Water Storage & Delivery c. Interbasin TransferThe Essentials for GA Water Planning The Relationship Between the Proposed GA State Comprehensive

Rosemond, Amy Daum

151

CoNiGa High Temperature Shape Memory Alloys  

E-Print Network [OSTI]

commercially successful SMAs such as NiTi and Cu-based alloys. In recent years, the CoNiGa system has emerged as a new ferromagnetic shape memory alloy with some compositions exhibiting high martensitic transformation temperatures which makes CoNiGa a potential...

Dogan, Ebubekir

2011-10-21T23:59:59.000Z

152

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

E-Print Network [OSTI]

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

Luryi, Serge

153

Partially filled intermediate band of Cr-doped GaN films  

SciTech Connect (OSTI)

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.

Sonoda, S. [Department of Electronics, Kyoto Institute of Technology, Kyoto 606-8585 (Japan)

2012-05-14T23:59:59.000Z

154

Elastic properties of Pu metal and Pu-Ga alloys  

SciTech Connect (OSTI)

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.

Soderlind, P; Landa, A; Klepeis, J E; Suzuki, Y; Migliori, A

2010-01-05T23:59:59.000Z

155

GaAs/AlGaAs quantum wells with indirect-gap AlGaAs barriers for solar cell applications  

SciTech Connect (OSTI)

We have fabricated GaAs/AlGaAs quantum well (QW) solar cells in which 3?nm-thick QWs and indirect-gap Al{sub 0.78}Ga{sub 0.22}As barriers are embedded, and we studied extraction processes of photogenerated carriers in this QW system. The photocurrent under 700?nm light illumination at voltages close to the open-circuit voltage shows only a small reduction, indicating that the carrier recombination inside QWs is largely suppressed. We attribute this result to an efficient extraction of electrons from the QWs through the X-valley of AlGaAs. The insertion of QWs is shown to be effective in extending the absorption wavelengths and in enhancing the photocurrent. The use of indirect-gap materials as barriers is found to enhance carrier extraction processes, and result in an improved performance of QW solar cells.

Noda, T., E-mail: NODA.Takeshi@nims.go.jp; Otto, L. M.; Elborg, M.; Jo, M.; Mano, T.; Kawazu, T.; Han, L. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Sakaki, H. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Toyota Technological Institute, Nagoya 468-8511 (Japan)

2014-03-24T23:59:59.000Z

156

IEEE Energy2030 Atlanta, Georgia, USA  

E-Print Network [OSTI]

to air pollution, cause wear and tear to machinery and require significant investments in system backup

Oren, Shmuel S.

157

Atlanta, Georgia: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector GeneralDepartmentAUDIT REPORTOpenWendeGuo Feng Bio EnergyInstituteFundingAtiaia Energia

158

Atlanta Chemical Engineering LLC | 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 on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 NoPublic Utilities Address: 160 EastMaine: Energy Resources JumpAspen Aerogels05. It is640623°

159

Output Harmonic Termination Techniques for AlGaN/GaN HEMT Power Amplifiers Using Active Integrated Antenna Approach  

E-Print Network [OSTI]

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

Itoh, Tatsuo

160

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

E-Print Network [OSTI]

AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors using barium strontium-effect transistors have been formed by incorporating barium strontium titanate (BST) deposited by rf magnetron in increased leakage. Due to its large dielectric constant, barium strontium ti- tanate [Ba1-xSrxTiO3, (BST

York, Robert A.

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Mn-doped Ga(As,P) and (Al,Ga)As ferromagnetic semiconductors: Electronic structure calculations  

E-Print Network [OSTI]

A remarkable progress towards functional ferromagnetic semiconductor materials for spintronics has been achieved in p-type (Ga,Mn)As. Robust hole-mediated ferromagnetism has, however, been observed also in other III-V hosts such as antimonides, Ga...

Masek, J.; Kudrnovsky, J.; Maca, F.; Sinova, Jairo; MacDonald, A. H.; Campion, R. P.; Gallagher, B. L.; Jungwirth, T.

2007-01-01T23:59:59.000Z

162

High-Performance Integrated Dual-Gate AlGaN/GaN Enhancement-Mode Transistor  

E-Print Network [OSTI]

In this letter, we present a new AlGaN/GaN enhancement-mode (E-mode) transistor based on a dual-gate structure. The dual gate allows the transistor to combine an E-mode behavior with low on-resistance and very high breakdown ...

Lu, Bin

163

Fabrication of quantum point contacts by engraving GaAsAlGaAs heterostructures with a diamond tip  

E-Print Network [OSTI]

by hot-filament chemical vapor deposition of polycrystalline diamond onto a prepat- terned siliconFabrication of quantum point contacts by engraving GaAsAlGaAs 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

Hohls, Frank

164

OPTIMIZATION OF GaN WINDOW LAYER FOR InGaN SOLAR CELLS USING POLARIZATION EFFECT  

E-Print Network [OSTI]

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

Honsberg, Christiana

165

Si-CMOS-Like Integration of AlGaN/GaN Dielectric-Gated High-Electron-Mobility Transistors  

E-Print Network [OSTI]

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...

Johnson, Derek Wade

2014-07-31T23:59:59.000Z

166

Analysis of the reduced thermal conductivity in InGaAs/GaAs quantum dot lasers from chirp characteristics  

E-Print Network [OSTI]

injection which we term "thermal impact" , the ther- mal conductivity of the active region is estimatedAnalysis of the reduced thermal conductivity in InGaAs/GaAs quantum dot lasers from chirp; published online 21 September 2006 The thermal conductivity of self-organized quantum dot QD active regions

Klotzkin, David

167

Diffusion of a Ga adatom on the GaAs(001)c(44)heterodimer surface: A first principles study  

E-Print Network [OSTI]

Diffusion of a Ga adatom on the GaAs(001)c(44)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

Khare, Sanjay V.

168

Electric field dependent radiative decay kinetics of polar InGaN/GaN quantum heterostructures at low fields  

E-Print Network [OSTI]

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

Demir, Hilmi Volkan

169

Optical study of hydrogen-irradiated GaAsN/GaAs heterostructures M. Geddo,1,a)  

E-Print Network [OSTI]

Optical study of hydrogen-irradiated GaAsN/GaAs heterostructures M. Geddo,1,a) M. Patrini,1 G; accepted 5 May 2011; published online 20 June 2011) The effect of hydrogen irradiation on the optical for fiber optic communications. These promising results in view of the development of waveguides deserve

170

An AlGaAsGaAs quantum cascade laser operating with a thermoelectric cooler for spectroscopy of NH3  

E-Print Network [OSTI]

out using a compact thermo-electrically cooled laser package. The QCL described here is designedAn AlGaAs­GaAs quantum cascade laser operating with a thermoelectric cooler for spectroscopy of NH3. Langford b a Department of Electronics and Electrical Engineering, Rankine Building, University of Glasgow

171

Wavelength-resolved low-frequency noise of GaInN/GaN green light emitting diodes  

E-Print Network [OSTI]

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

Wetzel, Christian M.

172

Infrared reflection of GaN and AlGaN thin film heterostructures with AlN buffer layers  

E-Print Network [OSTI]

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

Wetzel, Christian M.

173

Evaluation of the two-photon absorption characteristics of GaSb/GaAs quantum rings  

SciTech Connect (OSTI)

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.

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

174

Single photon emission from site-controlled InGaN/GaN quantum dots  

SciTech Connect (OSTI)

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.

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

175

Large linear magnetoresistance in a GaAs/AlGaAs heterostructure  

SciTech Connect (OSTI)

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.

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

176

Sidewall passivation for InGaN/GaN nanopillar light emitting diodes  

SciTech Connect (OSTI)

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.

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

177

Enhanced optical property in quaternary GaInAsSb/AlGaAsSb quantum wells  

SciTech Connect (OSTI)

High quality GaInAsSb/AlGaAsSb quantum wells (QWs) have been grown by molecular beam epitaxy using proper interface treatments. By controlling the group-V elements at interfaces, we obtained excellent optical quality QWs, which were free from undesired localized trap states, which may otherwise severely affect the exciton recombination. Strong and highly efficient exciton emissions up to room temperature with a wavelength of 2.2 ?m were observed. A comprehensive investigation on the QW quality was carried out using temperature dependent and power dependent photoluminescence (PL) measurements. The PL emission intensity remains nearly constant at low temperatures and is free from the PL quenching from the defect induced localized states. The temperature dependent emission energy had a bulk-like behavior, indicating high quality well/barrier interfaces. Because of the uniformity of the QWs and smooth interfaces, the low temperature limit of inhomogeneous line width broadening is as small as 5?meV.

Lin, Chien-Hung, E-mail: chlin.ee97g@g2.nctu.edu.tw; Lee, Chien-Ping [Department of Electronics Engineering, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan (China)

2014-10-21T23:59:59.000Z

178

Strain relaxation effect by nanotexturing InGaN/GaN multiple quantum well  

SciTech Connect (OSTI)

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.

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

179

Field dependent emission rates in radiation damaged GaAs  

SciTech Connect (OSTI)

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.

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

180

Effect of Sb on the Properties of GaInP Top Cells (Presentation)  

SciTech Connect (OSTI)

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%.

Olson, J. M.; McMahon, W. E.; Kurtz, S.

2006-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Microscopic, electrical and optical studies on InGaN/GaN quantum wells based LED devices  

SciTech Connect (OSTI)

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.

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

182

Waveguide effect of GaAsSb quantum wells in a laser structure based on GaAs  

SciTech Connect (OSTI)

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.

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

183

Electrical spin injection using GaCrN in a GaN based spin light emitting diode  

SciTech Connect (OSTI)

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.

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

184

Beta-decay branching ratios of 62Ga  

E-Print Network [OSTI]

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.

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. Chaventr

2008-04-17T23:59:59.000Z

185

Linear and nonlinear optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell spherical quantum dot  

SciTech Connect (OSTI)

In this work, the optical properties of GaAs/Al{sub x}Ga{sub 1?x}As/GaAs/Al{sub y}Ga{sub 1?y}As multi-shell quantum dot heterostructure have been studied as a function of Al doping concentrations for cases with and without a hydrogenic donor atom. It has been observed that the absorption coefficient strength and/or resonant absorption wavelength can be adjusted by changing the Al content of inner-barrier and/or outer-barrier regions. Besides, it has been shown that the donor atom has an important effect on the control of the electronic and optical properties of the structure. The results have been presented as a function of the Al contents of the inner-barrier x and outer-barrier y regions and probable physical reasons have been discussed.

Emre Kavruk, Ahmet, E-mail: aekavruk@selcuk.edu.tr, E-mail: aekavruk@gmail.com; Koc, Fatih [Physics Department, Faculty of Sciences, Selcuk University, 42075 Konya (Turkey); Sahin, Mehmet, E-mail: mehmet.sahin@agu.edu.tr, E-mail: mehsahin@gmail.com [Physics Department, Faculty of Sciences, Selcuk University, 42075 Konya (Turkey); Department of Material Sciences and Nanotechnology Engineering, Abdullah Gul University, Kayseri (Turkey)

2013-11-14T23:59:59.000Z

186

Transverse acoustic actuation of Ni-Mn-Ga single crystals  

E-Print Network [OSTI]

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. ...

Simon, Jesse Matthew

2007-01-01T23:59:59.000Z

187

Lattice vibrations of pure and doped GaSe  

SciTech Connect (OSTI)

The Bridgman method is used to grow especially undoped and doped single crystals of GaSe. Composition and impurity content of the grown crystals were determined using X-ray fluorescence (XRF) method. X-ray diffraction, Raman scattering, photoluminescence (PL), and IR transmission measurements were performed at room temperature. The long wavelength lattice vibrations of four modifications of GaSe were described in the framework of modified one-layer linear-chain model which also takes into consideration the interaction of the selenium (Se) atom with the second nearest neighbor gallium (Ga) atom in the same layer. The existence of an eight-layer modification of GaSe is suggested and the vibrational frequencies of this modification are explained in the framework of a lattice dynamical model considered in the present work. Frequencies and the type of vibrations (gap, local, or resonance) for the impurity atoms were calculated and compared with the experimental results.

Allakhverdiev, K. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey) and Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan)]. E-mail: kerim.allahverdi@mam.gov.tr; Baykara, T. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Ellialtioglu, S. [Department of Physics, Middle East Technical University, Ankara 06531 (Turkey); Hashimzade, F. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Huseinova, D. [Institute of Physics, Azerbaijan National Academy of Sciences, Baku AZ1143 (Azerbaijan); Kawamura, K. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan); Kaya, A.A. [Materials Institute, Marmara Research Center, TUBITAK, Gebze/Kocaeli 41470 (Turkey); Kulibekov, A.M. [Department of Physics, Mugla University, Mugla 48000 (Turkey); Onari, S. [Institute of Materials Science, University of Tsukuba 305-8573 (Japan)

2006-04-13T23:59:59.000Z

188

Evaporation-based Ge/.sup.68 Ga Separation  

DOE Patents [OSTI]

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.

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

189

Anti-phase domains in cubic GaN  

SciTech Connect (OSTI)

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.

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

190

Fabrication of Two-Dimensional Photonic Crystals in AlGaInP/GaInP Membranes by Inductively Coupled Plasma Etching  

E-Print Network [OSTI]

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 ...

Chen, A.

191

p-doping-free InGaN/GaN light-emitting diode driven by three-dimensional hole gas  

SciTech Connect (OSTI)

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.

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

192

Epitaxial growth of Cu,,In,Ga...Se2 on GaAs,,110... and A. Rockett  

E-Print Network [OSTI]

. 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

Rockett, Angus

193

Reducing the efficiency droop by lateral carrier confinement in InGaN/GaN quantum-well nanorods  

E-Print Network [OSTI]

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.

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

194

Green (In,Ga,Al)P-GaP light-emitting diodes grown on high-index GaAs surfaces  

SciTech Connect (OSTI)

We report on green (550560?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.

Ledentsov, N. N., E-mail: nikolay.ledentsov@v-i-systems.com; Shchukin, V. A. [VI Systems GmbH, Hardenbergstr. 7, Berlin D-10623 (Germany); Lyytikinen, 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 fr Festkrperphysik, Technische Universitt Berlin, Hardenbergstrasse 36, Berlin D-10623 (Germany)

2014-11-03T23:59:59.000Z

195

Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk  

SciTech Connect (OSTI)

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.

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

196

The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa  

SciTech Connect (OSTI)

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.

zduran, Mustafa [Ahi Evran niversitesi Fen Edebiyat Fakltesi Fizik Blm, K?r?ehir (Turkey); Turgut, Kemal [Yksek Lisans ?rencisi, K?r?ehir (Turkey); Arikan, Nihat [Ahi Evran niversitesi E?itim Fakltesi ?lk?retim Blm, K?r?ehir (Turkey); ?yigr, Ahmet; Candan, Abdullah [Ahi Evran niversitesi Merkezi Ara?t?rma Laboratuvar?, K?r?ehir (Turkey)

2014-10-06T23:59:59.000Z

197

Reduced lattice temperature high-speed operation of pseudomorphic InGaAdGaAs field-effect transistors  

E-Print Network [OSTI]

,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

Kolodzey, James

198

60 GHz Harmonic Optoelectronic Up-Conversion Using an InAlAs/InGaAs Metamorphic High-Electron-Mobility Transistor on a GaAs Substrate  

E-Print Network [OSTI]

60 GHz Harmonic Optoelectronic Up-Conversion Using an InAlAs/InGaAs Metamorphic High optoelectronic up-conversion using an InAlAs/InGaAs metamorphic high-electron-mobility transistor (HEMT) on a Ga 1 GHz signals into a 60 GHz band. After investigating the dependences of optoelectronic mixing

Choi, Woo-Young

199

Organometallic Vapor Phase Epitaxy of n-GaSb and n-GaInAsSb for Low Resistance Ohmic Contacts  

SciTech Connect (OSTI)

A comparison of n-GaSb and n-GaInAsSb epilayers for ohmic contacts in GaSb-based devices is studied. The epilayers were grown by organometallic vapor phase epitaxy and doped with Te. At similar electron concentrations, the atomic Te concentration, as determined by secondary ion mass spectroscopy, is more than 2 times higher in n-GaSb compared to n-GaInAsSb. In addition, the electron mobility is lower in n-GaSb than n-GaInAsSb at similar electron concentrations. The electron concentration saturates at about 1.3 x 10{sup 18} cm{sup -3} for n-GaSb, but linearly increases for n-GaInAsSb. Pd/Ge/Au/Pt/Au metallization was studied for ohmic contacts. A specific contact resistivity of 1 x 10{sup -5}{Omega}-cm{sup 2} for n-GaSb was measured. The specific contact resistivity can be greatly improved by contacting n-GaInAsSb, and a significantly lower specific contact resistivity of 2 x 10{sup -6} {Omega}-cm{sup 2} for n-GaInAsSb was measured.

C.A. Wang; D.A. Shiau; R.K. Huang; C.T. Harris; M.K. Connors

2003-07-10T23:59:59.000Z

200

The crucial role of doping for high repetition rate monolithic mode locking of multiple quantum well GaAs/AlGaAs lasers  

E-Print Network [OSTI]

have been operated in GaAs/AlGaAs and InP/InGaAsP mul- tiple quantum well MQW materials showed no evidence of mode-locked operation. Band-edge absorption spectra are also presented which

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201

Low temperature carrier redistribution dynamics in InGaN/GaN quantum wells  

SciTech Connect (OSTI)

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.

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

202

Testing of ethylene propylene seals for the GA-4/GA-9 casks  

SciTech Connect (OSTI)

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.

Boonstra, R.H.

1993-08-01T23:59:59.000Z

203

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)

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.

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

204

Nano-scale luminescence characterization of individual InGaN/GaN quantum wells stacked in a microcavity using scanning transmission electron microscope cathodoluminescence  

SciTech Connect (OSTI)

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.

Schmidt, Gordon, E-mail: Gordon.Schmidt@ovgu.de; Mller, Marcus; Veit, Peter; Bertram, Frank; Christen, Jrgen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, 39106 Magdeburg (Germany); Glauser, Marlene; Carlin, Jean-Franois; Cosendey, Gatien; Butt, Raphal; Grandjean, Nicolas [Institute of Condensed Matter Physics, cole Polytechnique Fdrale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2014-07-21T23:59:59.000Z

205

Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe  

E-Print Network [OSTI]

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.

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

206

Active region based on graded-gap InGaN/GaN superlattices for high-power 440- to 470-nm light-emitting diodes  

SciTech Connect (OSTI)

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.

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

207

Sustainable Manufacturing via Multi-Scale, Physics-Based Process...  

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

microstruc- Pasadena, CA tural modeling tools for metals that encounter severe plastic deformation. Georgia Institute of Technology Atlanta, GA * Enhancement of machining...

208

2894 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 55, NO. 12, DECEMBER 2007 RFID Tag and RF Structures on a Paper Substrate  

E-Print Network [OSTI]

Institute of Technology, Atlanta, GA 30332 USA (e-mail: liyang@ece.gatech.edu; arida@ece.gatech.edu; gtg904e

Tentzeris, Manos

209

3450 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 57, NO. 11, NOVEMBER 2009 Design, Development and Integration of Novel  

E-Print Network [OSTI]

of Technology, Atlanta, GA 30308 USA (e-mail: arida@gatech.edu; liyang@ece.gatech.edu; etentze@ece. gatech

Tentzeris, Manos

210

Inkjet-Printing UHF Antenna for RFID and Sensing Applications on Liquid Crystal Polymer  

E-Print Network [OSTI]

, Georgia Institute ofTechnology, Atlanta, GA 30332-0250, USA E-mail: arida@ece.gatech.edu 2Frederick

Tentzeris, Manos

211

Novel Manufacturing Processes for Ultra-Low-Cost Paper-Based RFID Tags with Enhanced "Wireless Intelligence"  

E-Print Network [OSTI]

Georgia Institute ofTechnology Atlanta, GA 30332-0250 *E-mail: arida(ece.gatech.edu Abstract The objective

Tentzeris, Manos

212

Paper-Based Ultra-Low-Cost Integrated RFID Tags for Sensing and Tracking Applications Amin Rida*, Rushi Vyas, Serkan Basat, Antonio Ferrer-Vidal,  

E-Print Network [OSTI]

Georgia Institute ofTechnology, Atlanta, GA 30332-0250 *E-mail: arida@4~ece.mail.gatech.edu Abstract

Tentzeris, Manos

213

Adversarial Diplomacy and African American Politics  

E-Print Network [OSTI]

during the administration of Jimmy Carter compared to that154. Louis Martin, interview, 10 December 1980, Jimmy CarterPapers, Jimmy Carter Presidential Library, Atlanta, GA,

Williams II, Ronald Cartell

2011-01-01T23:59:59.000Z

214

METAL FOILS FOR DIRECT APPLICATION OF ABSORBER COATINGS ON SOLAR COLLECTORS  

E-Print Network [OSTI]

Sputtering for Depositing Solar Collector Coatings".AES Coatings for Solar Collectors Symposium. Atlanta. Ga.Surfaces on Flat Plate Solar Collectors". Proceedings of 2nd

Lampert, Carl M.

2011-01-01T23:59:59.000Z

215

METAL FOILS FOR DIRECT APPLICATION OF ABSORBER COATINGS ON SOLAR COLLECTORS  

E-Print Network [OSTI]

Surfaces on Flat Plate Solar Collectors". Proceedings of 2ndfor Depositing Solar Collector Coatings i i Proceedings ofAES Coatings for Solar Collectors Symposium. Atlanta. Ga.

Lampert, Carl M.

2011-01-01T23:59:59.000Z

216

A Survey and Critical Review of the Literature on Indoor Air Quality, Ventilation and Health Symptoms in Schools  

E-Print Network [OSTI]

from the California Healthy Building Study, Phase 1.ASHRAE IAQ 91 Healthy Buildings, Atlanta, GA, ASHRAE, 228-1 of the California Healthy Building Study. Indoor Air, 3:

Daisey, Joan M.

2010-01-01T23:59:59.000Z

217

E-Print Network 3.0 - african american patients Sample Search...  

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

Disorder... of Veterans Affairs Medical Center, Atlanta, GA African Americans in low-income, urban communities are at high... that low income African Americans living ... Source:...

218

NETL F 451.1/1-1, Categorical Exclusion Designation Form  

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

Existing Plants Division FY 2013 1012012 - 09302013 Steve Mascaro Atlanta, GA Optimization of Pressurized Oxy-Combustion with Flameless Reactor - Phase I Georgia Tech will...

219

NETL F 451.1/1-1, Categorical Exclusion Designation Form  

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

Plants Division FY 2013 1012012 - 09302013 Isaac "Andy" Aurelio Atlanta, GA Optimization of Pressurized Oxy-Combustion with Flameless Reactor - Phase I Georgia Tech will...

220

Daniel Phillips: Publications  

E-Print Network [OSTI]

[1], Sookyung Joo and Daniel Phillips. ... 2, 341-359 [MR 2002b:35235]. ... In Proceedings of Dynamic Systems and Applications, Vol.1 (Atlanta, GA, 1993),...

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

E-Print Network 3.0 - aerosol generators Sample Search Results  

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

Dodd Way, Atlanta, GA, 30332, U.S.A. Abstract. Atmospheric aerosols scatter and absorb solar Source: Bergin, Mike - Schools of Civil and Environmental Engineering & Earth and...

222

E-Print Network 3.0 - aerosol monitoring Sample Search Results  

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

Dodd Way, Atlanta, GA, 30332, U.S.A. Abstract. Atmospheric aerosols scatter and absorb solar Source: Bergin, Mike - Schools of Civil and Environmental Engineering & Earth and...

223

E-Print Network 3.0 - animal structures Sample Search Results  

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

1 Evaluating Animations as Student Aids in Learning Computer Algorithms Michael D. Byrne Psychology... Atlanta, GA 30332-0280 Abstract We conducted two experiments designed to...

224

E-Print Network 3.0 - approach infiltration des Sample Search...  

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

approaches unity, while... Performance of the Exterior Envelopes of Buildings VIII, ASHRAE, Atlanta, GA. 12;2 ABSTRACT Infiltration has... of the infiltration flow rate and...

225

TYPICAL HOT WATER DRAW PATTERNS BASED ON FIELD DATA  

E-Print Network [OSTI]

for Rating Residential Water Heaters. Atlanta, GA: ASHRAE,for Residential Water Heaters, Direct Heating Equipment, andthe Energy Consumption of Water Heaters. Title 10 Code of

Lutz, Jim

2014-01-01T23:59:59.000Z

226

NETL F 451.1/1-1, Categorical Exclusion Designation Form  

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

TX AMP Electric Vehicles: Union City, IN and Loveland, OH; CTE: Atlanta, GA; and UPSDirect Electric: Stafford Road, Stafford, TX; Sweetwater Lane and Mykawa Road, Houston,...

227

Review of Strategies and Technologies for Demand-Side Management on Isolated Mini-Grids  

E-Print Network [OSTI]

Center for Appropriate Technology. Alice Springs, Australia.Report of Intermediate Technology Consultants to Overseasand Communication Technologies and Development. Atlanta, GA.

Harper, Meg

2014-01-01T23:59:59.000Z

228

A probabilistic comparison of split and type 1 triangle cuts for two ...  

E-Print Network [OSTI]

Jun 1, 2010 ... Georgia Institute of Technology, Atlanta, GA 30332 ... by adding in a single round all possible cuts from the family) corresponding to the three...

2010-06-01T23:59:59.000Z

229

A Polyhedral Study of the Cardinality Constrained Knapsack Problem  

E-Print Network [OSTI]

Oct 2, 2001 ... Georgia Institute of Technology, Atlanta, GA 30332-0205 ... We present three families of non-trivial facet-defining inequalities that are lifted...

2001-10-05T23:59:59.000Z

230

ON PROJECTIONS OF SEMI-ALGEBRAIC SETS DEFINED BY FEW ...  

E-Print Network [OSTI]

The families of maps d and ? make D, into a double complex. Proof. ..... School of Mathematics, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A..

2006-12-12T23:59:59.000Z

231

Maximizing a class of submodular utility functions with constraints  

E-Print Network [OSTI]

Dec 30, 2014 ... Georgia Institute of Technology, Atlanta, GA 30332. December ... We propose a family of inequalities for the convex hull of P by exploiting sub-.

2014-12-30T23:59:59.000Z

232

An integer programming approach to the OSPF weight setting problem  

E-Print Network [OSTI]

Oct 18, 2006 ... Georgia Institute of Technology, 765 Ferst Drive, Atlanta GA 30332 .... In Section 3 we develop a family of valid inequalities to improve the.

2006-10-18T23:59:59.000Z

233

ON A REAL ANALOGUE OF BEZOUT INEQUALITY AND THE ...  

E-Print Network [OSTI]

Jul 12, 2014 ... realizable sign conditions of the family P restricted to Vl is bounded by ...... School of Mathematics, Georgia Institute of Technology, Atlanta, GA...

2014-07-12T23:59:59.000Z

234

On the number of homotopy types of fibres of a definable map  

E-Print Network [OSTI]

follows from Hardt's triviality theorem, and the finiteness of the family of sets S. ...... School of Mathematics, Georgia Institute of Technology, Atlanta, GA 30332,...

2006-05-21T23:59:59.000Z

235

On Lower Complexity Bounds for Large-Scale Smooth Convex ...  

E-Print Network [OSTI]

Georgia Institute of Technology, Atlanta, GA, USA. ... F of continuous convex functions on E. We assume that the family F is equipped with an oracle O which,.

2013-07-18T23:59:59.000Z

236

On the number of topological types occurring in a parametrized ...  

E-Print Network [OSTI]

In this paper we consider parametrized families of arrangements. ...... School of Mathematics, Georgia Institute of Technology, Atlanta, GA 30332, U.S.A..

2008-03-20T23:59:59.000Z

237

Maskless lateral epitaxial overgrowth of GaN on sapphire  

SciTech Connect (OSTI)

The authors demonstrate a technique of lateral epitaxial overgrowth (LEO) of GaN, termed maskless LEO, in which no mask is deposited prior to LEO regrowth. Instead, a bulk (> 2 {micro}m) GaN layer on sapphire is selectively dry etched, leaving {approximately} 5 {micro}m-wide stripe mesas oriented in the <10{bar 1}0>{sub GaN} direction, with a 20 {micro}m period. These stripes serve as seeds for LEO GaN growth, which proceeds from the tops of the stripes and expands laterally, resulting in a T, or overhang, morphology. As for LEO over an SiO{sub 2} mask, significant defect reduction (from {approximately} 10{sup 9} cm{sup {minus}2} to {approximately} 10{sup 6} cm{sup {minus}2}) is observed in cross-sectional transmission electron microscopy (TEM). Atomic force microscopy of the top surface of the LEO GaN reveals that no threading dislocations with screw component terminate at the surfaces of laterally overgrown regions. X-ray diffraction measurements reveal that the wings exhibit a crystallographic tilt away from the seed regions in an azimuth perpendicular to the stripe direction; the tilt angle ({approximately} 0.4--0.5{degree}) is relatively independent of growth temperature and wing aspect ratio.

Fini, P.; Marchand, H.; Ibbetson, J.P.; Moran, B.; Zhao, L.; Denbaars, S.P.; Speck, J.S.; Mishra, U.K.

1999-07-01T23:59:59.000Z

238

Pulsed laser annealing of Be-implanted GaN  

SciTech Connect (OSTI)

Postimplantation thermal processing of Be in molecular-beam-epitaxy-grown GaN by rapid thermal annealing (RTA) and pulsed laser annealing (PLA) was investigated. It has been found that the activation of Be dopants and the repair of implantation-induced defects in GaN films cannot be achieved efficiently by conventional RTA alone. On the other hand, good dopant activation and surface morphology and quality were obtained when the Be-implanted GaN film was annealed by PLA with a 248 nm KrF excimer laser. However, observations of off-resonant micro-Raman and high-resolution x-ray-diffraction spectra indicated that crystal defects and strain resulting from Be implantation were still existent after PLA, which probably degraded the carrier mobility and limited the activation efficiency to some extent. This can be attributed to the shallow penetration depth of the 248 nm laser in GaN, which only repaired the crystal defects in a thin near-surface layer, while the deeper defects were not annealed out well. This situation was significantly improved when the Be-implanted GaN was subjected to a combined process of PLA followed by RTA, which produced good activation of the dopants, good surface morphology, and repaired bulk and surface defects well.

Wang, H.T.; Tan, L.S.; Chor, E.F. [Centre for Optoelectronics, Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

2005-11-01T23:59:59.000Z

239

Theoretical investigation of electron-positive ion/atom interactions. [Clark Atlanta Univ. , Atlanta, Georgia  

SciTech Connect (OSTI)

Very brief summaries are given on three research topics. Electron impact elastic, excitation, and total cross sections for K were investigated by using elaborate Cl target wave functions in the close-coupling approximation. Photoionization cross sections from ground-state Na were calculated near the 2s[sup 2]2p[sup 5]3s and 2s2p[sup 6]3s inner-shell thresholds; also, the photoionization cross sections of excited 3p [sup 2]P[sup o] and 3d [sup 2]D states were calculated with the R-matrix methodology near the 2s2p[sup 6]3s thresholds. A numerical approach was developed to calculate the charge transfer matrix elements for ion-atom(ion) collisions; this was used for the proton-hydrogen collision problem as an illustration.

Msezane, A.Z.

1992-01-01T23:59:59.000Z

240

GaAs-based high temperature electrically pumped polariton laser  

SciTech Connect (OSTI)

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.

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

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Simulation of Npn and Pnp AlGaN/GaN heterojunction bipolar transistors performances: Limiting factors and optimum design  

SciTech Connect (OSTI)

The performance capabilities of Npn and Pnp AlGaN/GaN heterojunction bipolar transistors have been investigated by using a drift-diffusion transport model. Numerical results have been employed to study the effect of the p-type Mg doping and its incomplete ionization on device performance. The high base resistance induced by the deep acceptor level is found to be the cause of limited current gain values for Npn devices. Several computation approaches have been considered to improve their performance. Reasonable improvement of the DC current gain {beta} is observed by realistically reducing the base thickness in accordance with processing limitations. Base transport enhancement is also predicted by the introduction of a quasi-electric field in the base. The impact of the base resistivity on high-frequency characteristics is investigated for Npn AlGaN/GaN devices. Optimized predictions with maximum oscillation frequency value as high as f{sub MAX} = 20 GHz and a unilateral power gain--U = 25 dB make this bipolar GaN-based technology compatible with communication applications. Simulation results reveal that the restricted amount of free carriers from the p-doped emitter limits Pnp's DC performances operating in common emitter configuration. A preliminary analysis of r.f. characteristics for the Pnp counterpart indicates limited performance mainly caused by the degraded hole mobility.

MONIER,C.; REN,F.; HAN,JUNG; CHANG,PING-CHIH; SHUL,RANDY J.; LEE,K.P.; ZHANG,A.P.; BACA,ALBERT G.; PEARTON,S.J.

2000-04-25T23:59:59.000Z

242

Simple intrinsic defects in GaAs : numerical supplement.  

SciTech Connect (OSTI)

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.

Schultz, Peter Andrew

2012-04-01T23:59:59.000Z

243

AlP/GaP distributed Bragg reflectors  

SciTech Connect (OSTI)

Distributed Bragg reflectors with high reflectivity bands centered at wavelengths from 530 to 690 nm (green to red) based on AlP/GaP quarter-wave stacks are prepared on (001)GaP using gas-source molecular-beam epitaxy. Additionally, the complex refractive index of AlP is measured using spectroscopic ellipsometry within the range of 330-850 nm in order to facilitate an accurate reflector design. Structures consisting of 15 quarter-wave stacks reach a peak reflectance between 95% and 98%, depending on the spectral position of the maximum.

Emberger, Valentin; Hatami, Fariba; Ted Masselink, W. [Department of Physics, Humboldt-Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin (Germany); Peters, Sven [Sentech Instruments GmbH, Schwarzschildstr. 2, 12489 Berlin (Germany)

2013-07-15T23:59:59.000Z

244

Graphene/GaN diodes for ultraviolet and visible photodetectors  

SciTech Connect (OSTI)

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.

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

245

Corrosion-induced degradation of GaAs PHEMTs under operation in high humidity conditions  

E-Print Network [OSTI]

We have comprehensively investigated the degradation mechanism of AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors (PHEMTs) under operation in high humidity conditions. PHEMTs degradation under high humidity ...

Hisaka, Takayuki

246

Electric field engineering in GaN high electron mobility transistors  

E-Print Network [OSTI]

In the last few years, AlGaN/GaN high electron mobility transistors (HEMTs) have become the top choice for power amplification at frequencies up to 20 GHz. Great interest currently exists in industry and academia to increase ...

Zhao, Xu, S.M. Massachusetts Institute of Technology

2008-01-01T23:59:59.000Z

247

Site-controlled fabrication of Ga nanodroplets by focused ion beam  

SciTech Connect (OSTI)

Ga droplets are created by focused ion beam irradiation of GaAs surface. We report that ordered Ga droplets can be formed on the GaAs surface without any implantation damage. The droplets are characterized with bigger sizes than those droplets formed on damaged area. These aligned Ga droplets are formed via the migration of Ga atoms from ion irradiation area to the edge of undamaged GaAs surface and further nucleation into droplets. The morphological evolution and size distribution of these nanodroplets are investigated systematically with different beam irradiation time and incident angles. Based on this method, well positioned Ga nanodroplets, such as chains, are achieved by using focus ion beam patterning. The controllable assembly of droplets on undamaged semiconductor surface can be used to fabricate templates, to fabricate quantum structures and quantum devices by droplet epitaxy technique.

Xu, Xingliang; Wang, Zhiming M., E-mail: zhmwang@gmail.com [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China); Wu, Jiang; Li, Handong; Zhou, Zhihua [State Key Laboratory of Electronic Thin Film and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Wang, Xiaodong [Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China)

2014-03-31T23:59:59.000Z

248

Device-level thermal analysis of GaN-based electronics  

E-Print Network [OSTI]

Gallium nitride (GaN)-based microelectronics are one of the most exciting semiconductor technologies for high power density and high frequency electronics. The excellent electrical properties of GaN and its related alloys ...

Bagnall, Kevin Robert

2013-01-01T23:59:59.000Z

249

Light extraction in individual GaN nanowires on Si for LEDs  

E-Print Network [OSTI]

GaN-based nanowires hold great promise for solid state lighting applications because of their waveguiding properties and the ability to grow nonpolar GaN nanowire-based heterostructures, which could lead to increased light ...

Zhou, Xiang

250

High performance double pulse doped pseudomorphic AlGaAs/InGaAs transistors grown by molecular-beam epitaxy  

SciTech Connect (OSTI)

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.

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

251

Strong enhancement of terahertz emission from GaAs in InAs/GaAs quantum dot structures  

SciTech Connect (OSTI)

We report on the intense terahertz emission from InAs/GaAs quantum dot (QD) structures grown by molecular beam epitaxy. Results reveal that the QD sample emission was as high as 70% of that of a p-type InAs wafer, the most intense semiconductor emitter to date. Excitation wavelength studies showed that the emission was due to absorption in strained undoped GaAs, and corresponds to a two order-of-magnitude enhancement. Moreover, it was found that multilayer QDs emit more strongly compared with a single layer QD sample. At present, we ascribe the intense radiation to huge strain fields at the InAs/GaAs interface.

Estacio, Elmer; Pham, Minh Hong; Takatori, Satoru; Cadatal-Raduban, Marilou; Nakazato, Tomoharu; Shimizu, Toshihiko; Sarukura, Nobuhiko [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Somintac, Armando; Defensor, Michael; Awitan, Fritz Christian B.; Jaculbia, Rafael B.; Salvador, Arnel [National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines); Garcia, Alipio [Department of Physical Sciences, University of the Philippines, Baguio City 2600 (Philippines)

2009-06-08T23:59:59.000Z

252

High-performance broadband optical coatings on InGaN/GaN solar cells for multijunction device integration  

SciTech Connect (OSTI)

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.

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

253

Degradation of InGaN/GaN laser diodes investigated by micro-cathodoluminescence and micro-photoluminescence  

SciTech Connect (OSTI)

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.

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, Tullastrae 72, 79108 Freiburg (Germany)] [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastrae 72, 79108 Freiburg (Germany); Schade, L.; Karunakaran, M. A. [IMTEK, Freiburg University, Georges-Khler-Allee 103 D, 79110 Freiburg (Germany)] [IMTEK, Freiburg University, Georges-Khler-Allee 103 D, 79110 Freiburg (Germany); Schwarz, U. T. [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastrae 72, 79108 Freiburg (Germany) [Fraunhofer Institute for Applied Solid State Physics IAF, Tullastrae 72, 79108 Freiburg (Germany); IMTEK, Freiburg University, Georges-Khler-Allee 103 D, 79110 Freiburg (Germany)

2013-12-02T23:59:59.000Z

254

Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells  

SciTech Connect (OSTI)

We demonstrate THz intersubband absorption (15.626.1?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.

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

255

Remarkably reduced efficiency droop by using staircase thin InGaN quantum barriers in InGaN based blue light emitting diodes  

SciTech Connect (OSTI)

The efficiency droop of InGaN/GaN(InGaN) multiple quantum well (MQW) light emitting diodes (LEDs) with thin quantum barriers (QB) is studied. With thin GaN QB (3?nm6?nm thickness), the efficiency droop is not improved, which indicates that hole transport cannot be significantly enhanced by the thin GaN QBs. On the contrary, the efficiency droop was remarkably reduced by using a InGaN staircase QB (InGaN SC-QB) MQWs structure where InGaN SC-QBs lower the transport energy barrier of holes. The efficiency droop ratio was as low as 3.3% up to 200?A/cm{sup 2} for the InGaN SC-QB LED. By using monitoring QW with longer wavelength we observe a much uniform carrier distribution in the InGaN SC-QB LEDs, which reveals the mechanism of improvement in the efficiency droop.

Zhou, Kun; Ikeda, Masao, E-mail: mikeda2013@sinano.ac.cn, E-mail: jpliu2010@sinano.ac.cn; Liu, Jianping, E-mail: mikeda2013@sinano.ac.cn, E-mail: jpliu2010@sinano.ac.cn; Zhang, Shuming; Li, Deyao; Zhang, Liqun; Yang, Hui [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou (China); Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou (China); Cai, Jin; Wang, Hui; Wang, H. B. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou (China); Key Laboratory of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou (China); Suzhou Nanojoin Photonics Co., Ltd., Suzhou (China)

2014-10-27T23:59:59.000Z

256

Spin dependent transport properties of Mn-Ga/MgO/Mn-Ga magnetic tunnel junctions with metal(Mg, Co, Cr) insertion layer  

SciTech Connect (OSTI)

We report a first principles theoretical investigation of spin polarized quantum transport in Mn{sub 2}Ga/MgO/Mn{sub 2}Ga and Mn{sub 3}Ga/MgO/Mn{sub 3}Ga magnetic tunneling junctions (MTJs) with the consideration of metal(Mg, Co, Cr) insertion layer effect. By changing the concentration of Mn, our calculation shows a considerable disparity in transport properties: A tunneling magnetoresistance (TMR) ratio of 852% was obtained for Mn{sub 2}Ga-based MTJs, however, only a 5% TMR ratio for Mn{sub 3}Ga-based MTJs. In addition, the influence of insertion layer has been considered in our calculation. We found the Co insertion layer can increase the TMR of Mn{sub 2}Ga-based MTJ to 904%; however, the Cr insertion layer can decrease the TMR by 668%; A negative TMR ratio can be obtained with Mg insertion layer. Our work gives a comprehensive understanding of the influence of different insertion layer in Mn-Ga based MTJs. It is proved that, due to the transmission can be modulated by the interfacial electronic structure of insertion, the magnetoresistance ratio of Mn{sub 2}Ga/MgO/Mn{sub 2}Ga MTJ can be improved by inserting Co layer.

Liang, S. H.; Tao, L. L.; Liu, D. P., E-mail: dpliu@iphy.ac.cn; Han, X. F., E-mail: xfhan@iphy.ac.cn [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Y. [Institut Jean Lamour, UMR 7198, CNRS-Nancy Universit, BP 239, 54506 Vandoeuvre (France)

2014-04-07T23:59:59.000Z

257

Tunneling and nonlinear transport in a vertically coupled GaAs/AlGaAs double quantum wire system.  

SciTech Connect (OSTI)

We report low-dimensional tunneling in an independently contacted vertically coupled quantum wire system. This nanostructure is fabricated in a high quality GaAs/AlGaAs parallel double quantum well heterostructure. Using a unique flip chip technique to align top and bottom split gates to form low-dimensional constrictions in each of the independently contacted quantum wells we explicitly control the subband occupation of the individual wires. In addition to the expected two-dimensional (2D)-2D tunneling results, we have found additional tunneling features that are related to the one-dimensional quantum wires.

Seamons, John Andrew; Lilly, Michael Patrick; Reno, John Louis; Bielejec, Edward Salvador

2004-11-01T23:59:59.000Z

258

1.9 kV AlGaN/GaN Lateral Schottky Barrier Diodes on Silicon  

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

In this letter, we present AlGaN/GaN lateral Schottky barrier diodes on silicon with recessed anodes and dual field plates. A low specific on-resistance RON,SP (5.12 m?{center_dot}cm2), a low turn-on voltage (1.9 kV), were simultaneously achieved in devices with a 25 ?m anode/cathode separation, resulting in a power figure-of-merit (FOM) BV2/RON,SP of 727 MW{center_dot}cm2. The record high breakdown voltage of 1.9 kV is attributed to the dual field plate structure.

Zhu, Mingda [University of Notre Dame, IN (United States); Song, Bo [Cornell University, Ithaca, NY (United States); Qi, Meng [University of Notre Dame, IN (United States); Hu, Zongyang [University of Notre Dame, IN (United States); Nomoto, Kazuki [University of Notre Dame, IN (United States); Yan, Xiaodong [University of Notre Dame, IN (United States); Cao, Yu [IQE/HRL Labs; Johnson, Wayne [IQE, Westborough, MA (United States); Kohn, Erhard [University of Notre Dame, IN (United States); Jena, Debdeep [Cornell University, Ithaca, NY (United States); Xing, Grace Huili [Cornell University, Ithaca, NY (United States)

2015-04-01T23:59:59.000Z

259

Drift dominated InP/GaP photodiodes Yanning Sun a,*, Aristo Yulius a  

E-Print Network [OSTI]

Drift dominated InP/GaP photodiodes Yanning Sun a,*, Aristo Yulius a , Guohua Li b , Jerry MP photodiodes fabricated on GaP substrate with unique drift dominated design, which can build an electric field throughout the active region by varying the doping concentration. The InP/GaP photodiodes have been grown

Woodall, Jerry M.

260

DISSERTATION DEVICE PHYSICS OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS  

E-Print Network [OSTI]

DISSERTATION DEVICE PHYSICS OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS Submitted by Markus Gloeckler PHYSICS OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS BE ACCEPTED AS FULFILLING IN PART REQUIREMENTS OF Cu(In,Ga)Se2 THIN-FILM SOLAR CELLS Thin-film solar cells have the potential to be an important

Sites, James R.

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Hexagonal Growth Spirals on GaN Grown by Molecular Beam Epitaxy: Kinetics vs Thermodynamics  

E-Print Network [OSTI]

prepared, Ga-polar GaN(0001) templates. The surface morphology was studied using reflection high-energy-edge energy of 0.26 eV/?. They suggest that local conditions at step edges dominate the growth. 1 conducted ex situ using AFM. Desorption mass spectrometry (DMS) was used to measure the GaN growth rate. Our

Cohen, Philip I.

262

Surface plasmon enhanced InGaN light emitter Koichi Okamoto*a  

E-Print Network [OSTI]

is a very promising method for developing the super bright light emitting diodes (LEDs). Moreover, we foundGaN/GaN, light emitting diode, quantum well, internal quantum efficiency, solid-state light source 1. INTRODUCTION Since 1993, InGaN quantum wells (QW)-based light emitting diodes (LEDs) have been continuously

Okamoto, Koichi

263

TESLA-FEL 2007-03 Application of low cost GaAs LED as neutron  

E-Print Network [OSTI]

neutrons in unbiased Gallium Arsenide (GaAs) Light Emitting Diodes (LED) resulted in a reduction Keywords: COTS components, Displacement damage, Electron Linear Accelerator, GaAs Light emitting diode (LED) Gallium Arsenide (GaAs) light emitting diode (LED) for the assessment of integrated neutron fluence

264

Free carrier induced spectral shift for GaAs filled metallic hole arrays  

E-Print Network [OSTI]

. Soref, and J. A. D. Alamo, "Carrier-induced change in refractive index of InP, GaAs, and InGaAsP," IEEE-photon absorption (3PA) assisted by strongly enhanced local fields, reduce the refractive index of GaAs in ~200-nm thick active area through band filling and free carrier absorption. Therefore, the surface plasma wave

New Mexico, University of

265

Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy  

E-Print Network [OSTI]

Controlled oxygen doping of GaN using plasma assisted molecular-beam epitaxy A. J. Ptak, L. J-assisted molecular-beam epitaxy to study the dependence of oxygen incorporation on polarity and oxygen partial pressure. Oxygen incorporates at a rate ten times faster on nitrogen-polar GaN than on the Ga polarity

Myers, Tom

266

Properties of H, O and C in GaN  

SciTech Connect (OSTI)

The electrical properties of the light ion impurities H, O and C in GaN have been examined in both as-grown and implanted material. H is found to efficiently passivate acceptors such as Mg, Ca and C. Reactivation occurs at {ge} 450 C and is enhanced by minority carrier injection. The hydrogen does not leave the GaN crystal until > 800 C, and its diffusivity is relatively high ({approximately} 10{sup {minus}11} cm{sup 2}/s) even at low temperatures (< 200 C) during injection by wet etching, boiling in water or plasma exposure. Oxygen shows a low donor activation efficiency when implanted into GaN, with an ionization level of 30--40 meV. It is essentially immobile up to 1,100 C. Carbon can produce low p-type levels (3 {times} 10{sup 17} cm{sup {minus}3}) in GaN during MOMBE, although there is some evidence it may also create n-type conduction in other nitrides.

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

1996-04-01T23:59:59.000Z

267

Ohmic contacts to p-type GaP  

E-Print Network [OSTI]

thickness used in this scheme. The samples were annealed for I @n at temperatures ranging from 3 5 0 to 4 5 0 'C. Lower values of the contact resistivity than those of the Si/Pd/Zn/Pd/p-GaP scheme were achieved by depositing an Aluminum layer on the top...

Jorge Estevez, Humberto Angel

1996-01-01T23:59:59.000Z

268

Gallium Arsenide (GaAs) EDWARD D. PALIK  

E-Print Network [OSTI]

constants of pure (semi-insulating) GaAs are derived from a number of papers including the far-infrared at. [4]; the near-IR work of Pikhtin and Yas'kov [5]; the calorim- etry work of Christensen et al. [6 reflection work of Philipp and Ehrenreich [9]; and the synchrotron transmission work of Cardona et al. [10

Pulfrey, David L.

269

Theory of weak localization in ferromagnetic (Ga,Mn)As  

E-Print Network [OSTI]

We study quantum interference corrections to the conductivity in (Ga,Mn)As ferromagnetic semiconductors using a model with disordered valence-band holes coupled to localized Mn moments through a p-d kinetic-exchange interaction. We find that at Mn...

Garate, Ion; Sinova, Jairo; Jungwirth, T.; MacDonald, A. H.

2009-01-01T23:59:59.000Z

270

Response of GaAs to fast intense laser pulses  

E-Print Network [OSTI]

Motivated by recent experiments, we have performed simulations which show in detail how the electrons and ions in GaAs respond to fast intense laser pulses (with durations of order 100 fs and intensities of order 1-10 TW/cm(2)). The method of tight...

Graves, JS; Allen, Roland E.

1998-01-01T23:59:59.000Z

271

Recombination in Low-Bandgap InGaAs  

SciTech Connect (OSTI)

We review our investigation of recombination in In{sub x}Ga{sub 1-x}As with indium concentrations ranging between x=0.53 (i.e., lattice-matched to InP) and x=0.78. External radiative efficiency measurements were used to study how defect-related and Auger mechanisms compete with radiative recombination. The results indicated that deep mid-gap levels facilitate defect-related recombination in lattice-matched InGaAs while shallower levels play a more important role in the indium-rich alloys. Subsequent sub-bandgap photoluminescence measurements confirmed the presence of deep levels in the lattice-matched InGaAs. The superlinear excitation dependence of the sub-gap emission led to a defect-related deep-donor/shallow-acceptor pair model. Recent cathodoluminescence measurements of the subgap transitions show no spatial contrast, supporting the assignment of this mechanism to evenly distributed point defects. We hypothesize that the deep states observed in lattice-matched InGaAs are related to imperfections in the incorporation of indium or gallium, which become less likely as the indium concentration is increased.

Gfroerer, T. H.; Wanlass, M. W.

2006-01-01T23:59:59.000Z

272

Ballistic thermal point contacts made of GaAs nanopillars  

SciTech Connect (OSTI)

We measure the thermal conductance of GaAs pillars that are only a few nanometers long. Our observations can be understood with a simple model, in which the pillars constitute thermal point contacts between 3D phonon reservoirs. Moreover, first measurements of the electronic transport through these pillars are presented.

Bartsch, Th.; Wetzel, A.; Sonnenberg, D.; Schmidt, M.; Heyn, Ch.; Hansen, W. [Institut fr Angewandte Physik und Zentrum fr Mikrostrukturforschung, Universitt Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany)

2013-12-04T23:59:59.000Z

273

GA Tech Campus Emergency Response Team STANDARD OPERATING PROCEDURE  

E-Print Network [OSTI]

GA Tech Campus Emergency Response Team GT-CERT STANDARD OPERATING PROCEDURE 09/29/2010 #12;2 Table as a condition for the appointment and continuing maintenance of membership. GT-CERT members operate for and to respond to emergency/disaster situations. 2.0 Purpose To establish procedures for the activation

274

High-quality InP on GaAs  

E-Print Network [OSTI]

In addition to traditional telecommunication applications, devices based on InP have received increased attention for high-performance electronics. InP growth on GaAs is motivated by the fact that InP wafers are smaller, ...

Quitoriano, Nathaniel Joseph

2006-01-01T23:59:59.000Z

275

Substrate-dependent wetting layer formation during GaN growth: Impact on the morphology of the films  

SciTech Connect (OSTI)

We have compared epitaxial growth of GaN films on 6H-SiC(0001)-({radical}(3)x{radical}(3))R30 deg. -Ga and on (0001)-sapphire. Predeposited Ga layers were nitrided by ion beam assisted molecular beam epitaxy. Whereas on SiC the initially deposited Ga covers the substrate surface completely, on sapphire only Ga droplets are present. The different distribution of the predeposited Ga affects the morphology of GaN significantly. Scanning electron microscopy and atomic force microscopy analysis of the grown films show that the complete wetting of the SiC substrate with Ga enhances finally the size and the flatness of GaN terraces and thus the quality of the film. X-ray photoelectron spectroscopy measurements reveal that metallic Ga resides also on top of the GaN films during the growth.

Sidorenko, A.; Peisert, H.; Neumann, H.; Chasse, T. [Universitaet Tuebingen, Institut fuer Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, D-72076 Tuebingen (Germany); Leibniz-Institut fuer Oberflaechenmodifizierung e.V. Permoserstrasse 15, D-04318 Leipzig (Germany); Universitaet Tuebingen, Institut fuer Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, D-72076 Tuebingen (Germany)

2007-08-15T23:59:59.000Z

276

Testing a GaAs cathode in SRF gun  

SciTech Connect (OSTI)

RF electron guns with a strained superlattice GaAs cathode are expected to generate polarized electron beams of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface and lower cathode temperature. We plan to install a bulk GaAs:Cs in a SRF gun to evaluate the performance of both the gun and the cathode in this environment. The status of this project is: In our 1.3 GHz 1/2 cell SRF gun, the vacuum can be maintained at nearly 10{sup -12} Torr because of cryo-pumping at 2K. With conventional activation of bulk GaAs, we obtained a QE of 10% at 532 nm, with lifetime of more than 3 days in the preparation chamber and have shown that it can survive in transport from the preparation chamber to the gun. The beam line has been assembled and we are exploring the best conditions for baking the cathode under vacuum. We report here the progress of our test of the GaAs cathode in the SRF gun. Future particle accelerators, such as eRHIC and the ILC require high-brightness, high-current polarized electrons. Strained superlattice GaAs:Cs has been shown to be an efficient cathode for producing polarized electrons. Activation of GaAs with Cs,O(F) lowers the electron affinity and makes it energetically possible for all the electrons, excited into the conduction band that drift or diffuse to the emission surface, to escape into the vacuum. Presently, all operating polarized electron sources, such as the CEBAF, are DC guns. In these devices, the excellent ultra-high vacuum extends the lifetime of the cathode. However, the low field gradient on the photocathode's emission surface of the DC guns limits the beam quality. The higher accelerating gradients, possible in the RF guns, generate a far better beam. Until recently, most RF guns operated at room temperature, limiting the vacuum to {approx}10{sup -9} Torr. This destroys the GaAs's NEA surface. The SRF guns combine the excellent vacuum conditions of DC guns and the high accelerating gradient of the RF guns, potentially offering a long lived cathode with very low emittance. Testing this concept requires preparation of the cathode, transportation to the SRF gun and evaluation of the performance of the cathode and the gun at cryogenic temperatures. In our work at BNL, we successfully activated the bulk GaAs in the preparation chamber. The highest quantum efficient was 10% at 532 nm that fell to 0.5% after 100 hours. We explored three different ways to activate the GaAs. We verified that the GaAs photocathode remains stable for 30 hours in a 10{sup -11} Torr vacuum. Passing the photocathode through the low 10{sup -9} Torr transfer section in several seconds caused the QE to drop to 0.8%. The photocathode with 0.8% QE can be tested for the SRF gun. The gun and beam pipe were prepared and assembled. After baking at 200 C baking, the vacuum of the gun and beam pipe can sustain a low 10{sup -11} Torr at room temperature. The final test to extract electrons from the gun is ongoing. In this paper, we discuss our progress with this SRF gun and the results of the photocathode in preparation chamber and in magnet transfer line.

Wang, E.; Kewisch, J.; Ben-Zvi, I.; Burrill, A.; Rao, T.; Wu, Q.; Holmes, D.

2011-03-28T23:59:59.000Z

277

Determination of subband energies and 2DEG characteristics of Al{sub x}Ga{sub 1?x}N/GaN heterojunctions using variational method  

SciTech Connect (OSTI)

A physics-based model based on the variational method for analyzing the two dimensional electron gas (2DEG) characteristics of polar AlGaN/GaN heterojunctions is developed. The 2DEG carrier concentration, the first and second energy subbands, and the position of the Fermi energy level are calculated for various barrier thicknesses, Al mole fractions, background dopant concentrations, and gate voltages for gated AlGaN/GaN heterojunctions. The results are in good agreement with the data reported based on self-consistent method. Whereas the aforementioned report has dealt with specific values of Al mole fraction, barrier thickness, and unintentional doping level, the present work provides a basis for calculating the 2DEG characteristics for the full range of these parameters. Furthermore, according to the proposed model, the applicability of the triangular approximation of the quantum well in AlGaN/GaN heterojunctions is evaluated.

Manouchehri, Farzin; Valizadeh, Pouya; Kabir, M. Z., E-mail: kabir@encs.concordia.ca [Department of Electrical and Computer Engineering, Concordia University, Montreal, H3G 1M8 (Canada)

2014-03-15T23:59:59.000Z

278

Ultrasensitive detection of Hg{sup 2+} using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor  

SciTech Connect (OSTI)

An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg{sup 2+}. The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg{sup 2+} and thymines were combined. The current response of this Hg{sup 2+} ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg{sup 2+} ions on the surface by the highly specific thymine-Hg{sup 2+}-thymine recognition. The dynamic linear range for Hg{sup 2+} detection has been determined in the concentrations from 10{sup ?14} to 10{sup ?8} M and a detection limit below 10{sup ?14} M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg{sup 2+} detection till now.

Cheng, Junjie [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Li, Jiadong; Miao, Bin; Wu, Dongmin, E-mail: dmwu2008@sinano.ac.cn [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wang, Jine; Pei, Renjun, E-mail: rjpei2011@sinano.ac.cn [Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

2014-08-25T23:59:59.000Z

279

Quaternary InGaAsSb Thermophotovoltaic Diodes  

SciTech Connect (OSTI)

In{sub x}Ga{sub 1-x}As{sub y}Sb{sub 1-y} thermophotovoltaic (TPV) diodes were grown lattice-matched to GaSb substrates by Metal Organic Vapor Phase Epitaxy (MOVPE) in the bandgap range of E{sub G} = 0.5 to 0.6eV. InGaAsSb TPV diodes, utilizing front-surface spectral control filters, are measured with thermal-to-electric conversion efficiency and power density of {eta}{sub TPV} = 19.7% and PD =0.58 W/cm{sup 2} respectively for a radiator temperature of T{sub radiator} = 950 C, diode temperature of T{sub diode} = 27 C, and diode bandgap of E{sub G} = 0.53eV. Practical limits to TPV energy conversion efficiency are established using measured recombination coefficients and optical properties of front surface spectral control filters, which for 0.53eV InGaAsSb TPV energy conversion is {eta}{sub TPV} = 28% and PD = 0.85W/cm{sup 2} at the above operating temperatures. The most severe performance limits are imposed by (1) diode open-circuit voltage (VOC) limits due to intrinsic Auger recombination and (2) parasitic photon absorption in the inactive regions of the module. Experimentally, the diode V{sub OC} is 15% below the practical limit imposed by intrinsic Auger recombination processes. Analysis of InGaAsSb diode electrical performance vs. diode architecture indicate that the V{sub OC} and thus efficiency is limited by extrinsic recombination processes such as through bulk defects.

MW Dashiell; JF Beausang; H Ehsani; GJ Nichols; DM Depoy; LR Danielson; P Talamo; KD Rahner; EJ Brown; SR Burger; PM Foruspring; WF Topper; PF Baldasaro; CA Wang; R Huang; M Connors; G Turner; Z Shellenbarger; G Taylor; J Li; R Martinelli; D Donetski; S Anikeev; G Belenky; S Luryi

2006-03-09T23:59:59.000Z

280

Comparison of electrostatic and localized plasmon induced light enhancement in hybrid InGaN/GaN quantum wells  

SciTech Connect (OSTI)

The light enhancement phenomena in InGaN/GaN multi-quantum wells (MQWs) infiltrated with metal nanoparticles (NPs) are studied using resonant and off-resonant localized plasmon interactions. The emission and recombination characteristics of carriers in InGaN/GaN MQW structures with inverted hexagonal pits (IHPs) are modified distinctly depending on the nature of their interaction with the metal NPs and with the pumping and emitted photons. It is observed that the emission intensity of light is significantly enhanced when the emission energy is off-resonant to the localized plasmon frequency of the metal nanoparticles. This results in enhanced emission from MQW due to Au nanoparticles and from IHPs due to Ag nanoparticles. At resonant-plasmon frequency of the Ag NPs, the emission from MQWs is quenched due to the re-absorption of the emitted photons, or due to the drift carriers from c-plane MQWs towards the NPs because of the Coulomb forces induced by the image charge effect.

Lin, Jie; Llopis, Antonio; Krokhin, Arkadii; Neogi, Arup, E-mail: arup@unt.edu [Department of Physics, University of North Texas, Denton, Texas 76203 (United States); Pereira, Sergio [CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Watson, Ian M. [SUPA, Institute of Photonics, University of Strathclyde, Glasgow (United Kingdom)

2014-06-16T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Projected Performance of Three- and Four-Junction Devices Using GaAs and GaInP  

E-Print Network [OSTI]

This paper explores the efficiencies expected for three- and four-junction devices for both space and terrestrial applications. For space applications, the effects of temperature and low concentration are investigated. For terrestrial applications, a concentration of 500 suns is assumed and the theoretical efficiencies are calculated as a function of spectral variations including the effects of air mass, turbidity, and water-vapor content. INTRODUCTION Ga 0.5 In 0.5 P/GaAs two-terminal, two-junction solar cells, invented and developed at the National Renewable Energy Laboratory, are in production at both TECSTAR and Spectrolab. The immediate market for these devices is in space; a future (potentially larger) market is terrestrial concentrator systems. The next-generation cells will add additional junction(s) in order to increase the efficiency. Work on a three-junction cell using an active Ge junction under the Ga 0.5 In 0.5 P/GaAs dual-junction cell has already been reported [1]. Ho...

Gainp; S. R. Kurtz; Sarah R. Kurtz; D. Myers; D. Myers; J.M. Olson; J. M. Olson

1997-01-01T23:59:59.000Z

282

Electrical, thermal, and species transport properties of liquid eutectic Ga-In and Ga-In-Sn from first principles  

SciTech Connect (OSTI)

Using ab initio molecular dynamics, the atomic structure and transport properties of eutectic Ga-In and Ga-In-Sn are investigated. The Kubo-Greenwood (K-G) and the Ziman-Faber (Z-F) formulations and the Wiedemann-Franz (W-F) law are used for the electrical and electronic thermal conductivity. The species diffusivity and the viscosity are also predicted using the mean square displacement and the Stokes-Einstein (S-E) relation. Alloying Ga causes more disordered structure, i.e., broadening the atomic distance near the In and Sn atoms, which reduces the transport properties and the melting temperature. The K-G treatment shows excellent agreement with the experimental results while Z-F treatment formula slightly overestimates the electrical conductivity. The predicted thermal conductivity also shows good agreement with the experiments. The species diffusivity and the viscosity are slightly reduced by the alloying of Ga with In and Sn atoms. Good agreements are found with available experimental results and new predicted transport-property results are provided.

Yu, Seungho; Kaviany, Massoud, E-mail: kaviany@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)] [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2014-02-14T23:59:59.000Z

283

Dependence on proton energy of degradation of AlGaN/GaN high electron mobility transistors  

SciTech Connect (OSTI)

The effects of proton irradiation energy on dc, small signal, and large signal rf characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) were investigated. AlGaN/GaN HEMTs were irradiated with protons at fixed fluence of 51015/cm2 and energies of 5, 10, and 15 MeV. Both dc and rf characteristics revealed more degradation at lower irradiation energy, with reductions of maximum transconductance of 11%, 22%, and 38%, and decreases in drain saturation current of 10%, 24%, and 46% for HEMTs exposed to 15, 10, and 5MeV protons, respectively. The increase in device degradation with decreasing proton energy is due to the increase in linear energy transfer and corresponding increase in nonionizing energy loss with decreasing proton energy in the active region of the HEMTs. After irradiation, both subthreshold drain leakage current and reverse gate current decreased more than 1 order of magnitude for all samples. The carrier removal rate was in the range 121 336 cm1 over the range of proton energies employed in this study

Liu, L. [University of Florida, Gainesville; Xi, Y. Y. [University of Florida, Gainesville; Wang, Y.l. [University of Florida; Ren, F. [University of Florida; Pearton, S. J. [University of Florida; Kim, H.-Y. [Korea University; Kim, J. [Korea University; Fitch, Robert C [Air Force Research Laboratory, Wright-Patterson AFB, OH; Walker, Dennis E [Air Force Research Laboratory, Wright-Patterson AFB, OH; Chabak, Kelson D [Air Force Research Laboratory, Wright-Patterson AFB, OH; Gillespie, James k [Air Force Research Laboratory, Wright-Patterson AFB, OH; Tetlak, Stephen E [Air Force Research Laboratory, Wright-Patterson AFB, OH; Via, Glen D [Air Force Research Laboratory, Wright-Patterson AFB, OH; Crespo, Antonio [Air Force Research Laboratory, Wright-Patterson AFB, OH; Kravchenko, Ivan I [ORNL

2013-01-01T23:59:59.000Z

284

Plasmonic terahertz detectors based on a high-electron mobility GaAs/AlGaAs heterostructure  

SciTech Connect (OSTI)

In order to characterize magnetic field (B) tunable THz plasmonic detectors, spectroscopy experiments were carried out at liquid helium temperatures and high magnetic fields on devices fabricated on a high electron mobility GaAs/AlGaAs heterostructure. The samples were either gated (the gate of a meander shape) or ungated. Spectra of a photovoltage generated by THz radiation were obtained as a function of B at a fixed THz excitation from a THz laser or as a function of THz photon frequency at a fixed B with a Fourier spectrometer. In the first type of measurements, the wave vector of magnetoplasmons excited was defined by geometrical features of samples. It was also found that the magnetoplasmon spectrum depended on the gate geometry which gives an additional parameter to control plasma excitations in THz detectors. Fourier spectra showed a strong dependence of the magnetoplasmon resonance amplitude on the conduction-band electron filling factor which was explained within a model of the electron gas heating with THz radiation. The study allows to define both the advantages and limitations of plasmonic devices based on high-mobility GaAs/AlGaAs heterostructures for THz detection at low temperatures and high magnetic fields.

Bia?ek, M., E-mail: marcin.bialek@fuw.edu.pl; Witowski, A. M.; Grynberg, M.; ?usakowski, J. [Faculty of Physics, University of Warsaw, ul. Ho?a 69, 00-681 Warsaw (Poland); Orlita, M.; Potemski, M. [Laboratoire National des Champs Magnetiques Intenses, CNRS-UJF-UPS-INSA, 25, avenue des Martyrs, 38042 Grenoble (France); Czapkiewicz, M. [Institute of Physics, PAS, al. Lotnikw 32/46, 02-668 Warsaw (Poland); Wrbel, J. [Institute of Physics, PAS, al. Lotnikw 32/46, 02-668 Warsaw (Poland); Faculty of Mathematics and Natural Sciences, Rzeszw University, al. Rejtana 16A, 35-959 Rzeszw (Poland); Umansky, V. [Weizmann Institute of Science, Rehevot 76100 (Israel)

2014-06-07T23:59:59.000Z

285

Ultra High p-doping Material Research for GaN Based Light Emitters  

SciTech Connect (OSTI)

The main goal of the Project is to investigate doping mechanisms in p-type GaN and AlGaN and controllably fabricate ultra high doped p-GaN materials and epitaxial structures. Highly doped p-type GaN-based materials with low electrical resistivity and abrupt doping profiles are of great importance for efficient light emitters for solid state lighting (SSL) applications. Cost-effective hydride vapor phase epitaxial (HVPE) technology was proposed to investigate and develop p-GaN materials for SSL. High p-type doping is required to improve (i) carrier injection efficiency in light emitting p-n junctions that will result in increasing of light emitting efficiency, (ii) current spreading in light emitting structures that will improve external quantum efficiency, and (iii) parameters of Ohmic contacts to reduce operating voltage and tolerate higher forward currents needed for the high output power operation of light emitters. Highly doped p-type GaN layers and AlGaN/GaN heterostructures with low electrical resistivity will lead to novel device and contact metallization designs for high-power high efficiency GaN-based light emitters. Overall, highly doped p-GaN is a key element to develop light emitting devices for the DOE SSL program. The project was focused on material research for highly doped p-type GaN materials and device structures for applications in high performance light emitters for general illumination P-GaN and p-AlGaN layers and multi-layer structures were grown by HVPE and investigated in terms of surface morphology and structure, doping concentrations and profiles, optical, electrical, and structural properties. Tasks of the project were successfully accomplished. Highly doped GaN materials with p-type conductivity were fabricated. As-grown GaN layers had concentration N{sub a}-N{sub d} as high as 3 x 10{sup 19} cm{sup -3}. Mechanisms of doping were investigated and results of material studies were reported at several International conferences providing better understanding of p-type GaN formation for Solid State Lighting community. Grown p-type GaN layers were used as substrates for blue and green InGaN-based LEDs made by HVPE technology at TDI. These results proved proposed technical approach and facilitate fabrication of highly conductive p-GaN materials by low-cost HVPE technology for solid state lighting applications. TDI has started the commercialization of p-GaN epitaxial materials.

Vladimir Dmitriev

2007-06-30T23:59:59.000Z

286

Influence of strain induced by AlN nucleation layer on the electrical properties of AlGaN/GaN heterostructures on Si(111) substrate  

SciTech Connect (OSTI)

The crack-free metal-organic chemical vapor deposition (MOCVD) grown AlGaN/GaN heterostructures on Si substrate with modified growth conditions of AlN nucleation layer (NL) and its influence on the electrical and structural properties of conductive GaN layer are presented. From the Hall electrical measurements, a gradual decrease of two-dimensional electron gas (2DEG) concentration near heterointerface as the function of NL thickness is observed possibly due to the reduction in difference of piezoelectric polarization charge densities between AlGaN and GaN layers. It also indicates that the minimum tensile stress and a relatively less total dislocation density for high pressure grown NL can ensure a 20 % increment in mobility at room temperature irrespective of the interface roughness. The thickness and pressure variations in NL and the subsequent changes in growth mode of AlN contributing to the post growth residual tensile stress are investigated using X-ray diffraction and Raman scattering experiments, respectively. The post growth intrinsic residual stress in top layers of heterostructures arises from lattice mismatches, NL parameters and defect densities in GaN. Hence, efforts to reduce the intrinsic residual stress in current conducting GaN layer give an opportunity to further improve the electrical characteristics of AlGaN/GaN device structures on Si.

Christy, Dennis; Watanabe, Arata; Egawa, Takashi [Research Center for Nano-Device and System, Nagoya Institute of Technology, Nagoya, 466-8555 (Japan)

2014-10-15T23:59:59.000Z

287

GaAsSb-based heterojunction tunnel diodes for tandem solar cell interconnects  

SciTech Connect (OSTI)

We report a new approach to tunnel junctions that employs a pseudomorphic GaAsSb layer to obtain a band alignment at a InGaAs or InAlAs p-n junction favorable for forward bias tunneling. Since the majority of the band offset between GaAsSb and InGaAs or InAlAs is in the valence band, when an GaAsSb layer is placed at an InGaAs or InAlAs p-n junction the tunneling distance is reduced and the tunneling current is increased. For all doping levels studied, the presence of the GaAsSb-layer enhanced the forward tunneling characteristics. In fact, in a InGaAs/GaAsSb tunnel diode a peak tunneling current sufficient for a 1000 sun intercell interconnect was achieved with p = 1.5{times}l0{sup 18} cm{sup -3} while a similarly doped all-InGaAs diode was rectifying. This approach affords a new degree of freedom in designing tunnel junctions for tandem solar cell interconnects. Previously only doping levels could be varied to control the tunneling properties. Our approach relaxes the doping requirements by employing a GaAsSb-based heterojunction.

Zolper, J.C.; Klem, J.F.; Plut, T.A.; Tigges, C.P.

1995-01-01T23:59:59.000Z

288

Bending properties of epoxy resin matrix composites filled with NiMnGa ferromagnetic shape memory alloy powders  

E-Print Network [OSTI]

Bending properties of epoxy resin matrix composites filled with NiMnGa ferromagnetic shape memoryMnGa Composite materials Mechanical properties Microstructure Two types of epoxy resin matrix composites filledMnGa epoxy resin composites were reported, yet the bending property of NiMnGa-polymer smart composites has

Zheng, Yufeng

289

INCREASED CELL EFFICIENCY IN InGaAs THIN FILM SOLAR CELLS WITH DIELECTRIC AND METAL BACK REFLECTORS  

E-Print Network [OSTI]

INCREASED CELL EFFICIENCY IN InGaAs THIN FILM SOLAR CELLS WITH DIELECTRIC AND METAL BACK REFLECTORS solar cells using back reflectors. We studied absorption enhancement in InGaAs and InGaAsP thin film and metal, on InGaAs thin film solar cell performance by device modeling and nu- merical simulations. DEVICE

Atwater, Harry

290

Metal-insulator-semiconductor structures on p-type GaAs with low interface state density  

E-Print Network [OSTI]

Metal-insulator-semiconductor structures on p-type GaAs with low interface state density Zhi Chen properties of in situ deposited Si3N4 /Si/p-GaAs metal-insulator-semiconductor structures have been offered by a low gate leakage technology in GaAs, such as metal insulator structures, func- tional Ga

Chen, Zhi

291

Method of plasma etching Ga-based compound semiconductors  

DOE Patents [OSTI]

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent to the process chamber. The process chamber contains a sample comprising a Ga-based compound semiconductor. The sample is in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. The method includes flowing SiCl.sub.4 gas into the chamber, flowing Ar gas into the chamber, and flowing H.sub.2 gas into the chamber. RF power is supplied independently to the source electrode and the platen. A plasma is generated based on the gases in the process chamber, and regions of a surface of the sample adjacent to one or more masked portions of the surface are etched to create a substantially smooth etched surface including features having substantially vertical walls beneath the masked portions.

Qiu, Weibin; Goddard, Lynford L.

2012-12-25T23:59:59.000Z

292

Method of plasma etching GA-based compound semiconductors  

DOE Patents [OSTI]

A method of plasma etching Ga-based compound semiconductors includes providing a process chamber and a source electrode adjacent thereto. The chamber contains a Ga-based compound semiconductor sample in contact with a platen which is electrically connected to a first power supply, and the source electrode is electrically connected to a second power supply. SiCl.sub.4 and Ar gases are flowed into the chamber. RF power is supplied to the platen at a first power level, and RF power is supplied to the source electrode. A plasma is generated. Then, RF power is supplied to the platen at a second power level lower than the first power level and no greater than about 30 W. Regions of a surface of the sample adjacent to one or more masked portions of the surface are etched at a rate of no more than about 25 nm/min to create a substantially smooth etched surface.

Qiu, Weibin; Goddard, Lynford L.

2013-01-01T23:59:59.000Z

293

Study of reflection and transport in the microwave photo-excited GaAs/AlGaAs two dimensional electron system  

SciTech Connect (OSTI)

We present the results of a concurrent experimental study of microwave reflection and transport in the GaAs/AlGaAs two dimensional electron gas system and correlate observed features in the reflection with the observed transport features. The experimental results are compared with expectations based on theory.

Ye, Tianyu; Mani, Ramesh G. [Department of Physics and Astronomy, Georgia State University, Atlanta GA 30303 (United States); Wegscheider, Werner [Laboratorium fr Festkrperphysik, ETH Zrich, 8093 Zrich (Switzerland)

2013-12-04T23:59:59.000Z

294

GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates Melissa J. Archer,1,a  

E-Print Network [OSTI]

GaInP/GaAs dual junction solar cells on Ge/Si epitaxial templates Melissa J. Archer,1,a Daniel C Richard R. King,2 and Harry A. Atwater1 1 California Institute of Technology, Pasadena, California 91125, USA 2 Spectrolab, Inc., Sylmar, California 91342, USA 3 Aonex Technologies, Pasadena, California 91106

Atwater, Harry

295

FIRST DEMONSTRATION OF MONOLITHIC InP-BASED InAlAs/InGaAsP/InGaAs TRIPLE JUNCTION SOLAR CELLS  

E-Print Network [OSTI]

FIRST DEMONSTRATION OF MONOLITHIC InP-BASED InAlAs/InGaAsP/InGaAs TRIPLE JUNCTION SOLAR CELLS Robyn C. Law 1 1 Spectrolab, Inc., A Boeing Company, Sylmar, California 91342, USA 2 California Institute of Technology, Pasadena, California 91125, USA ABSTRACT Spectrolab has demonstrated the first lattice matched In

Atwater, Harry

296

Ga lithography in sputtered niobium for superconductive micro and nanowires  

SciTech Connect (OSTI)

This work demonstrates the use of focused ion beam (FIB) implanted Ga as a lithographic mask for plasma etching of Nb films. Using a highly collimated Ga beam of a FIB, Nb is implanted 12?nm deep with a 14?nm thick Ga layer providing etch selectivity better than 15:1 with fluorine based etch chemistry. Implanted square test patterns, both 10??m by 10??m and 100??m by 100??m, demonstrate that doses above than 7.5??10{sup 15?}cm{sup ?2} at 30?kV provide adequate mask protection for a 205?nm thick, sputtered Nb film. The resolution of this dry lithographic technique is demonstrated by fabrication of nanowires 75?nm wide by 10??m long connected to 50??m wide contact pads. The residual resistance ratio of patterned Nb films was 3. The superconducting transition temperature (T{sub c})?=?7.7?K was measured using a magnetic properties measurement system. This nanoscale, dry lithographic technique was extended to sputtered TiN and Ta here and could be used on other fluorine etched superconductors such as NbN, NbSi, and NbTi.

Henry, M. David; Wolfley, Steve; Monson, Todd; Lewis, Rupert [Sandia National Labs, MESA Facility, P.O. Box 5800, Albuquerque, New Mexico 87185-1084 (United States)

2014-08-18T23:59:59.000Z

297

InGaAsSb thermophotovoltaic diode physics evaluation  

SciTech Connect (OSTI)

The hotside operating temperatures for many projected thermophotovoltaic (TPV) conversion system applications are approximately 1,000 C, which sets an upper limit on the TPV diode bandgap of 0.6 eV from efficiency and power density considerations. This bandgap requirement has necessitated the development of new diode material systems, never previously considered for energy generation. To date, InGaAsSb quaternary diodes grown lattice-matched on GaSb substrates have achieved the highest performance. This report relates observed diode performance to electro-optic properties such as minority carrier lifetime, diffusion length and mobility and provides initial links to microstructural properties. This analysis has bounded potential diode performance improvements. For the 0.52 eV InGaAsSb diodes used in this analysis the measured dark current is 2 {times} 10{sup {minus}5} A/cm{sup 2}, versus a potential Auger limit 1 {times} 10{sup {minus}5} A/cm{sup 2}, a radiative limit of 2 {times} 10{sup {minus}6} A/cm{sup 2} (no photon recycling), and an absolute thermodynamic limit of 1.4 {times} 10{sup {minus}7} A/cm{sup 2}. These dark currents are equivalent to open circuit voltage gains of 20 mV (7%), 60 mV (20%) and 140 mV (45%), respectively.

Charache, G.W.; Baldasaro, P.F.; Danielson, L.R. [Lockheed-Martin, Inc., Schenectady, NY (United States)] [and others

1998-06-01T23:59:59.000Z

298

GaSb substrates with extended IR wavelength for advanced space based applications  

SciTech Connect (OSTI)

GaSb substrates have advantages that make them attractive for implementation of a wide range of infrared (IR) detectors with higher operating temperatures for stealth and space based applications. A significant aspect that would enable widespread commercial application of GaSb wafers for very long wavelength IR (VLWIR) applications is the capability for transmissivity beyond 15 m. Due largely to the GaSb (antisite) defect and other point defects in undoped GaSb substrates, intrinsic GaSb is still slightly p-type and strongly absorbs in the VLWIR. This requires backside thinning of the GaSb substrate for IR transmissivity. An extremely low n-type GaSb substrate is preferred to eliminate thinning and provide a substrate solution for backside illuminated VLWIR devices. By providing a more homogeneous radial distribution of the melt solute to suppress GaSb formation and controlling the cooling rate, ultra low doped n:GaSb has been achieved. This study examines the surface properties and IR transmission spectra of ultra low doped GaSb substrates at both room and low temperatures. Atomic force microscopy (AFM), homoepitaxy by MBE, and infrared Fourier transform (FTIR) analysis was implemented to examine material quality. As compared with standard low doped GaSb, the ultra low doped substrates show over 50% transmission and consistent wavelength transparency past 23 m with improved %T at low temperature. Homoepitaxy and AFM results indicate the ultra low doped GaSb has a low thermal desorbtion character and qualified morphology. In summary, improvements in room temperature IR transmission and extended wavelength characteristics have been shown consistently for ultra low doped n:GaSb substrates.

Allen, Lisa P.; Flint, Patrick; Dallas, Gordon; Bakken, Daniel; Blanchat, Kevin; Brown, Gail J.; Vangala, Shivashankar R.; Goodhue, William D.; Krishnaswami, Kannan

2009-05-01T23:59:59.000Z

299

Liquid Crystalline Polymer (LCP) Based Lumped-Element Bandpass Filters for Multiple WirelessApplications'  

E-Print Network [OSTI]

, Inc., Atlanta, GA 30332, USA Abstract - This paper presents for the first time the design* *Schoolof Electrical Engineering, Georga Institute of Technology,Atlanta, GA 30332,USA **JacketMicro Devices the sides used as inpdoutput terminals thus minimizing radiation losses and EM1 interference, 2) using

Swaminathan, Madhavan

300

2196 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 53, NO. 6, JUNE 2005 Layout-Level Synthesis of RF Inductors and Filters  

E-Print Network [OSTI]

is with Jacket Micro Devices Inc., Atlanta, GA, 30308 USA. M. Swaminathan is with the Department of Electrical Devices Inc., Atlanta, GA, 30308 USA. Digital Object Identifier 10.1109/TMTT.2005.848782 factor and stripline configuration are within 5% of data obtained from electromagnetic (EM) simulations. For RF

Swaminathan, Madhavan

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301

Alternative Fuels Data Center: DeKalb County Turns Trash to Gas  

Alternative Fuels and Advanced Vehicles Data Center [Office of Energy Efficiency and Renewable Energy (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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative Fuels Data Center Home Page onAlternativeConnecticut Information to someone

302

Polarity driven simultaneous growth of free-standing and lateral GaAsP epitaxial nanowires on GaAs (001) substrate  

SciTech Connect (OSTI)

Simultaneous growth of ?111?{sub B} free-standing and [110] lateral GaAsP epitaxial nanowires on GaAs (001) substrates were observed and investigated by electron microscopy and crystallographic analysis. It was found that the growth of both free-standing and lateral ternary nanowires via Au catalysts was driven by the fact that Au catalysts prefer to maintain low-energy (111){sub B} interfaces with surrounding GaAs(P) materials: in the case of free-standing nanowires, Au catalysts maintain (111){sub B} interfaces with their underlying GaAsP nanowires; while in the case of lateral nanowires, each Au catalyst remain their side (111){sub B} interfaces with the surrounding GaAs(P) material during the lateral nanowire growth.

Sun, Wen; Xu, Hongyi [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia)] [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia); Guo, Yanan [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia) [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia); Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Gao, Qiang; Hoe Tan, Hark; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia)] [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Zou, Jin, E-mail: j.zou@uq.edu.au [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia) [Materials Engineering, The University of Queensland, St Lucia QLD 40732 (Australia); Centre for Microscopy and Microanalysis, The University of Queensland, St Lucia QLD 4072 (Australia)

2013-11-25T23:59:59.000Z

303

Theoretical comparison of multiple quantum wells and thick-layer designs in InGaN/GaN solar cells  

SciTech Connect (OSTI)

This theoretical work analyzes the photovoltaic effect in non-polar InGaN/GaN solar cells. Our electronic transport model considers quantum behaviors related to confinement, tunneling, electron-phonon, and electron-photon scatterings. Based on this model, we compare a multiple quantum wells cell with its thick-layer counterpart. We show that the structure of multiple quantum wells is a promising design providing better compromise between photon-absorption and electronic transport. This balance is necessary since these two phenomena are shown to be antagonist in nanostructure based solar cells. In these devices, we also show that phonon absorption increases the short-circuit current, while phonon emission reduces the open-circuit voltage.

Cavassilas, Nicolas; Michelini, Fabienne; Bescond, Marc [Aix Marseille Univ, CNRS, IM2NP UMR 7334, 13384 Marseille (France)

2014-08-11T23:59:59.000Z

304

Carrier recombination mechanisms and efficiency droop in GaInN/GaN light-emitting diodes  

SciTech Connect (OSTI)

We model the carrier recombination mechanisms in GaInN/GaN light-emitting diodes as R=An+Bn{sup 2} +Cn{sup 3} +f(n) , where f(n) represents carrier leakage out of the active region. The term f(n) is expanded into a power series and shown to have higher-than-third-order contributions to the recombination. The total third-order nonradiative coefficient (which may include an f(n) leakage contribution and an Auger contribution) is found to be 810{sup ?29} ?cm{sup 6} ?s{sup ?1} . Comparison of the theoretical ABC+f(n) model with experimental data shows that a good fit requires the inclusion of the f(n) term.

Dai, Qi; Shan, Qifeng; Wang, Jing; Chhajed, Sameer; Cho, Jaehee; Schubert, E. Fred; Crawford, Mary H.; Koleske, Daniel D.; Kim, Min-Ho; Park, Yongjo

2010-01-01T23:59:59.000Z

305

Carrier-induced change in refractive index of InP, GaAs, and InGaAsP  

SciTech Connect (OSTI)

The authors have theoretically estimated the change in refractive index {Delta}{ital n} produced by injection of free carriers in InP, GaAs, and InGaAsP. Bandfilling (Burstein-Moss effect), band-gap shrinkage, and free-carrier absorption (plasma effect) were included. Carrier concentrations of 10{sup 16}/cm{sup 3} to 10{sup 19}/cm{sup 3} and photon energies of 0.8 to 2.0 eV were considered. Predictions of {Delta}{ital n} are in reasonably good agreement with the limited experimental data available. Refractive index changes as large as 10{sup {minus} 2} are predicted for carrier concentrations of 10{sup 18}/cm{sup 3}, suggesting that low-loss optical phase modulators and switches using carrier injection are feasible in these materials.

Bennett, B.R. (Dept. of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA (US)); Soref, R.A. (Solid State Sciences Directorate, Rome Air Development Center, Hanscom Air Force Base, Bedford, MA (US)); Del Alamo, J.A. (Dept. of Electrical Engineering and Computer Science, Massachussets Institute of Technology, Cambridge, MA (US))

1990-01-01T23:59:59.000Z

306

Sensitivity of absorption spectra to surface segregation in InGaN/GaN quantum well structures  

SciTech Connect (OSTI)

We investigate the influence of the indium surface segregation on absorption spectra in InGaN/GaN quantum well structures having different indium amount. Results of the mathematical modeling show that such influence is more pronounced in quantum well structures with high indium amounts. The origin of this effect is related to the interplay between the indium surface segregation and internal electrostatic fields. Our theoretical analysis is performed using semiconductor Bloch equations within the Hartree-Fock approximation including into consideration excitonic effects. Results of the global sensitivity analysis evidence that the influence of the indium surface segregation is less than one order of magnitude in comparison with the impact of the quantum-well width and indium molar fraction. Also, the influence of the indium surface segregation is not the same for each interface of the quantum well.

Klymenko, M. V.; Shulika, O. V. [Lab. Photonics, Kharkov National University of Radio Electronics, Kharkov, 61166 (Ukraine); Sukhoivanov, I. A. [Department of Electronics, Engineering Division, University of Guanajuato, Salamanca, Guanajuato, 36885 (Mexico)

2014-05-15T23:59:59.000Z

307

Monolithic phosphor-free InGaN/GaN quantum dot wavelength converter white light emitting diodes  

SciTech Connect (OSTI)

We report the characteristics of phosphor-free self-organized InGaN/GaN quantum dot wavelength converter white light emitting diodes grown by plasma assisted molecular beam epitaxy. The exciting quantum dots, in which electrically injected carriers recombine, are blue-emitting and the converter dots are red-emitting. We have studied the effect of tuning the number of dot layers and the peak emission wavelength of the exciting and converter dots on the nature of the emitted white light, in terms of the chromaticity coordinates and correlated color temperature. Depending on the values of these wavelengths, color temperatures in the range of 44206700?K have been derived at a current density of 45?A/cm{sup 2} across multiple devices. The variation of the color temperature with change in injection current is found to be very small.

Jahangir, Shafat; Bhattacharya, Pallab, E-mail: pkb@eecs.umich.edu [Center for Photonics and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109-2122 (United States); Pietzonka, Ines; Strassburg, Martin [OSRAM Opto Semiconductors GmbH, Leibnizstrasse 4, Regensburg (Germany)

2014-09-15T23:59:59.000Z

308

ArF laser-based quantum well intermixing in InGaAs/InGaAsP heterostructures  

SciTech Connect (OSTI)

Radiation from a 193 nm ArF laser was investigated to modify surface properties of InGaAs/InGaAsP quantum well (QW) heterostructures and introduce defects required to enhance intermixing during the annealing process. A top 200 nm thick sacrificial layer of InP served as a reservoir for laser generated defects. The irradiation with up to 90 pulses at 65-150 mJ/cm{sup 2} allowed to generate an array of 1.2x1 mm{sup 2} sites of QW intermixed material, with bandgap energy blueshifted up to 107 nm. We discuss the mechanism and advantages of this approach for postgrowth wafer level fabrication of multibandgap QW material.

Genest, Jonathan; Beal, Romain; Aimez, Vincent; Dubowski, Jan J. [Department of Electrical and Computer Engineering, Center of Excellence for Information Engineering, Universite de Sherbrooke, Sherbrooke, Quebec J1K 2R1 (Canada)

2008-08-18T23:59:59.000Z

309

X-ray diffraction analysis and scanning micro-Raman spectroscopy of structural irregularities and strains deep inside the multilayered InGaN/GaN heterostructure  

SciTech Connect (OSTI)

High-resolution X-ray diffraction analysis and scanning confocal Raman spectroscopy are used to study the spatial distribution of strains in the In{sub x}Ga{sub 1-x}N/GaN layers and structural quality of these layers in a multilayered light-emitting diode structure produced by metal-organic chemical vapor deposition onto (0001)-oriented sapphire substrates. It is shown that elastic strains almost completely relax at the heterointerface between the thick GaN buffer layer and In{sub x}Ga{sub 1-x}N/GaN buffer superlattice. It is established that the GaN layers in the superlattice are in a stretched state, whereas the alloy layers are in a compressed state. In magnitude, the stretching strains in the GaN layers are lower than the compressive strains in the InGaN layers. It is shown that, as compared to the buffer layers, the layers of the superlattice contain a smaller number of dislocations and the distribution of dislocations is more randomly disordered. In micro-Raman studies on scanning through the thickness of the multilayered structure, direct evidence is obtained for the asymmetric gradient distributions of strains and crystal imperfections of the epitaxial nitride layers along the direction of growth. It is shown that the emission intensity of the In{sub x}Ga{sub 1-x}N quantum well is considerably (more than 30 times) higher than the emission intensity of the GaN barrier layers, suggesting the high efficiency of trapping of charge carriers by the quantum well.

Strelchuk, V. V., E-mail: Strelch@isp.kiev.ua; Kladko, V. P.; Avramenko, E. A.; Kolomys, O. F.; Safryuk, N. V.; Konakova, R. V. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine); Yavich, B. S., E-mail: byavich@soptel.ru [ZAO Svetlana-Optoelectronics (Russian Federation); Valakh, M. Ya.; Machulin, V. F.; Belyaev, A. E. [National Academy of Sciences of Ukraine, Lashkaryov Institute of Semiconductor Physics (Ukraine)

2010-09-15T23:59:59.000Z

310

Effect of Mg ionization efficiency on performance of Npn AlGaN/GaN heterojunction bipolar transistors  

SciTech Connect (OSTI)

A drift-diffusion transport model has been used to examine the performance capabilities of AlGaN/GaN Npn heterojunction bipolar transistors (HBTs). The Gummel plot from the first GaN-based HBT structure recently demonstrated is adjusted with simulation by using experimental mobility and lifetime reported in the literature. Numerical results have been explored to study the effect of the p-type Mg doping and its incomplete ionization in the base. The high base resistance induced by the deep acceptor level is found to be the cause of limiting current gain values. Increasing the operating temperature of the device activates more carriers in the base. An improvement of the simulated current gain by a factor of 2 to 4 between 25 and 300 C agrees well with the reported experimental results. A preliminary analysis of high frequency characteristics indicates substantial progress of predicted rf performances by operating the device at higher temperature due to a reduced extrinsic base resistivity.

MONIER,C.; PEARTON,S.J.; CHANG,PING-CHIH; BACA,ALBERT G.

2000-03-10T23:59:59.000Z

311

Deep Levels in p-Type InGaAsN Lattice Matched to GaAs  

SciTech Connect (OSTI)

Deep level transient spectroscopy (DLTS) measurements were utilized to investigate deep level defects in metal-organic chemical deposition (MOCVD)-grown unintentionally doped p-type InGaAsN films lattice matched to GaAs. The as-grown material displayed a high concentration of deep levels distributed within the bandgap, with a dominant hole trap at E{sub v} + 0.10 eV. Post-growth annealing simplified the deep level spectra, enabling the identification of three distinct hole traps at 0.10 eV, 0.23 eV, and 0.48 eV above the valence band edge, with concentrations of 3.5 x 10{sup 14} cm{sup {minus}3}, 3.8 x 10{sup 14} cm{sup {minus}3}, and 8.2 x 10{sup 14} cm{sup {minus}3}, respectively. A direct comparison between the as-grown and annealed spectra revealed the presence of an additional midgap hole trap, with a concentration of 4 x 10{sup 14} cm{sup {minus}3} in the as-grown material. The concentration of this trap is sharply reduced by annealing, which correlates with improved material quality and minority carrier properties after annealing. Of the four hole traps detected, only the 0.48 eV level is not influenced by annealing, suggesting this level may be important for processed InGaAsN devices in the future.

Allerman, A.A.; Jones, E.D.; Kaplar, R.J.; Kurtz, S.R.; Kwon, D.; Ringel, S.A.

1999-03-02T23:59:59.000Z

312

Avalanche buildup time of an InP/InGaAsP/InGaAs APD at high gain  

SciTech Connect (OSTI)

Under a high-gain operating condition, the presence of a multiplication process in the InGaAs(P) regions of an InP/InGaAsP/InGaAs avalanche photodiode having a structure of separated absorption and multiplication regions (SAM-APD) could lead to significant enhancement of the avalanche buildup time. As a result, the bandwidth of the device could be reduced considerably. The dependence of the avalanche multiplication factor and the intrinsic response time on the reverse bias voltage, the heterointerface field, the doping concentrations, and the width of the InP layer are examined in detail for the case in which hole injection is assumed. It is shown, for example, that for a fixed value of doping concentrations, the reduction of the excess noise factor and the enhancement of the gain-bandwidth product of the device can be made at the same time by a proper increase of the width of the InP layer.

Hsieh, H.C.; Sargeant, W. (Iowa State Univ. of Science and Technology, Ames, IA (USA). Dept. of Electrical Engineering)

1989-09-01T23:59:59.000Z

313

Materials physics and device development for improved efficiency of GaN HEMT high power amplifiers.  

SciTech Connect (OSTI)

GaN-based microwave power amplifiers have been identified as critical components in Sandia's next generation micro-Synthetic-Aperture-Radar (SAR) operating at X-band and Ku-band (10-18 GHz). To miniaturize SAR, GaN-based amplifiers are necessary to replace bulky traveling wave tubes. Specifically, for micro-SAR development, highly reliable GaN high electron mobility transistors (HEMTs), which have delivered a factor of 10 times improvement in power performance compared to GaAs, need to be developed. Despite the great promise of GaN HEMTs, problems associated with nitride materials growth currently limit gain, linearity, power-added-efficiency, reproducibility, and reliability. These material quality issues are primarily due to heteroepitaxial growth of GaN on lattice mismatched substrates. Because SiC provides the best lattice match and thermal conductivity, SiC is currently the substrate of choice for GaN-based microwave amplifiers. Obviously for GaN-based HEMTs to fully realize their tremendous promise, several challenges related to GaN heteroepitaxy on SiC must be solved. For this LDRD, we conducted a concerted effort to resolve materials issues through in-depth research on GaN/AlGaN growth on SiC. Repeatable growth processes were developed which enabled basic studies of these device layers as well as full fabrication of microwave amplifiers. Detailed studies of the GaN and AlGaN growth of SiC were conducted and techniques to measure the structural and electrical properties of the layers were developed. Problems that limit device performance were investigated, including electron traps, dislocations, the quality of semi-insulating GaN, the GaN/AlGaN interface roughness, and surface pinning of the AlGaN gate. Surface charge was reduced by developing silicon nitride passivation. Constant feedback between material properties, physical understanding, and device performance enabled rapid progress which eventually led to the successful fabrication of state of the art HEMT transistors and amplifiers.

Kurtz, Steven Ross; Follstaedt, David Martin; Wright, Alan Francis; Baca, Albert G.; Briggs, Ronald D.; Provencio, Paula Polyak; Missert, Nancy A.; Allerman, Andrew Alan; Marsh, Phil F.; Koleske, Daniel David; Lee, Stephen Roger; Shul, Randy John; Seager, Carleton Hoover; Tigges, Christopher P.

2005-12-01T23:59:59.000Z

314

GaNAsP: An intermediate band semiconductor grown by gas-source molecular beam epitaxy  

SciTech Connect (OSTI)

Dilute nitride GaNAsP thin films were grown via a GaAsP metamorphic buffer on GaP(100) substrate with gas-source molecular beam epitaxy. The compositions of this III-V-V-V compound were determined by channeling Rutherford backscattering spectroscopy and nuclear reaction analysis. Photoreflectance shows two distinctive transitions from the valence band to the split conduction bands due to N incorporation. Photoluminescence and optical absorption show the fundamental bandgap of Ga(N)AsP is largely tailored by the small amount of N. The observed multiband characteristics and the bandgap tunability of GaNAsP are two merits that fit into the intermediate-band solar cell roadmap, and GaNAsP of high crystal quality provides a strong candidate for intermediate band solar cell materials.

Kuang, Y. J. [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Yu, K. M.; Walukiewicz, W. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kudrawiec, R. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Institute of Physics, Wroclaw University of Technology, Wybrzeze, Wyspianskiego 27, 50-370 Wroclaw (Poland); Luce, A. V. [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States) [Electronic Materials Program, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Materials Science and Engineering, University of California, Berkeley, California 94720 (United States); Ting, M. [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Tu, C. W. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)] [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093 (United States)

2013-03-18T23:59:59.000Z

315

Low-cost, high-efficiency solar cells utilizing GaAs-on-Si technology  

SciTech Connect (OSTI)

This report describes work to develop technology to deposit GaAs on Si using a nucleation layer of atomic-layer-epitaxy-grown GaAs or AlAs on Si. This ensures two-dimensional nucleation and should lead to fewer defects in the final GaAs layer. As an alternative, we also developed technology for depositing GaAs on sawtooth-patterned Si. Preliminary studies showed that this material can have a very low defect density, [approximately] 1 [times] 10[sup 5] cm[sup [minus]5], as opposed to our conventionally grown GaAs on SL which has a typical defect density of over 1 [times]10[sup 7] cm[sup [minus]2]. Using these two now methods of GaAs-on-Si material growth, we made solar cells that are expected to show higher efficiencies than those of previous cells.

Vernon, S.M. (Spire Corp., Bedford, MA (United States))

1993-04-01T23:59:59.000Z

316

Ga[sub 13], Al[sub 13], GaAl[sub 12], and chromium-pillared montmorillonites: Acidity and reactivity for cumene conversion  

SciTech Connect (OSTI)

A comparison has been made of the acidic characters of a series of metal polyoxocation pillar interlayered clay minerals (M-PILCs) by studying the infrared spectra of adsorbed pyridine. These comparisons were made for Ga[sub 13]-, Al[sub 13]- and GaAl[sub 12]-PILCs, and for Na[sup +]-exchanged montmorillonite (Na-STx-1). The Ga[sub 13]-PILC, was found to exhibit the strongest Lewis acid sites, followed by the AL[sub 13]-, and GaAl[sub 12]-PILCs and then by the Ns-STx-1. The relative number of Lewis acid sites, however, was found to be much greater for the GaAl[sub 12]-PILC, particularly after calcination at higher temperatures, indicating that the Ga[sub 13] Lewis acid sites did not have as high a thermal stability. The Broensted acidic characters for the pillared clays depend on the pillar, and follow the general decreasing order of abundance of GaAl[sub 12]-, Al[sub 13], and Ga[sub 13]-PILC when expressed as absorbance per unit mass. When the acidities per unit surface area were estimated, however, the Ga[sub 13]-PILCs were found to have the greatest number. This indicated that while the pillars contribute to the PILC acidities primarily through increasing the exposed phyllosilicate sheet surface areas, there is also a significant effect arising from the acidic characters of the pillars themselves. The dehydrogenation activities of Ga[sub 13]-, GaAl[sub 12]-, Al[sub 13]-, and Na-STx-1, in addition to a chromium polyoxocation-PILC, were compared by observing the products formed upon reaction with the model compound cumene. The Ga[sub 13]- and chromium-PILCs and the Na-Stx-1 exhibited almost exclusively dehydrogenation activities, whereas the Al[sub 13]- and GaAl[sub 12]-PILCs exhibited both cracking and dehydrogenation behaviors. These results prove that the pillars themselves can very strongly effect the catalytic activities of the PILCs. 3 refs., 6 figs., 2 tabs.

Bradley, S.M.; Kydd, R.A. (Univ. of Calgary, Alberta (Canada))

1993-05-01T23:59:59.000Z

317

E-Print Network 3.0 - algorithm ga technique Sample Search Results  

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

for: algorithm ga technique Page: << < 1 2 3 4 5 > >> 1 GAMMA: Global Arrays Meets MATLAB Rajkiran Panuganti Summary: is a straightforward implementa- tion of a standard...

318

Evolution of ion-induced nanoparticle arrays on GaAs surfaces  

SciTech Connect (OSTI)

We have examined the evolution of irradiation-induced Ga nanoparticle (NP) arrays on GaAs surfaces. Focused-ion-beam irradiation of pre-patterned GaAs surfaces induces monotonic increases in the NP volume and aspect ratio up to a saturation ion dose, independent of NP location within the array. Beyond the saturation ion dose, the NP volume continues to increase monotonically while the NP aspect ratio decreases monotonically. In addition, the NP volumes (aspect ratios) are highest (lowest) for the corner NPs. We discuss the relative influences of bulk and surface diffusion on the evolution of Ga NP arrays.

Kang, M.; Al-Heji, A. A.; Shende, O.; Huang, S.; Jeon, S.; Goldman, R. S., E-mail: rsgold@umich.edu [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-2136 (United States); Beskin, I. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2014-05-05T23:59:59.000Z

319

Absorption and photoluminescence of ternary nanostructured Ge-S-Ga(In)glassy semiconductor systems  

SciTech Connect (OSTI)

The photoluminescence and luminescence excitation spectra and the edge and IR absorption of Ge-S-Ga(In) glassy semiconductor systems are studied. The observed shifts of the optical-absorption edge, photoluminescence spectra (a decrease in their full width at half-maximum), and luminescence excitation spectra to lower energies upon the introduction of Ga or In into Ge-S binary systems are due to the fact that Ga or In tend to interact with sulfur, rather than with germanium. As the content of Ga(In) in the system increases, the intensity of the absorption band associated with vibrations of the Ge-S bond decreases.

Babaev, A. A., E-mail: babaev-arif@mail.ru [Russian Academy of Sciences, Amirkhanov Institute of Physics, Dagestan Scientific Center (Russian Federation); Kudoyarova, V. Kh. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2013-07-15T23:59:59.000Z

320

Structural defects in GaN revealed by Transmission Electron Microscopy  

SciTech Connect (OSTI)

This paper reviews the various types of structural defects observed by Transmission Electron Microscopy in GaN heteroepitaxial layers grown on foreign substrates and homoepitaxial layers grown on bulk GaN substrates. The structural perfection of these layers is compared to the platelet self-standing crystals grown by High Nitrogen Pressure Solution. Defects in undoped and Mg doped GaN are discussed. Some models explaining the formation of inversion domains in heavily Mg doped layers that are possible defects responsible for the difficulties of p-doping in GaN are also reviewed.

Liliental-Weber, Zuzanna

2014-04-18T23:59:59.000Z

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321

The critical role of growth temperature on the structural and electrical properties of AlGaN/GaN high electron mobility transistor heterostructures grown on Si(111)  

SciTech Connect (OSTI)

This work is dedicated to the study of the growth by ammonia source molecular beam epitaxy of Al{sub x}Ga{sub 1-x}N/GaN high electron mobility transistors on (111) oriented silicon substrates. The effect of growth conditions on the structural and electrical properties of the heterostructures was investigated. It is shown that even a slight variation in the growth temperature of the thick GaN buffer on AlN/GaN stress mitigating layers has a drastic influence on these properties via a counterintuitive effect on the dislocation density. Both in situ curvature measurements and ex situ transmission electron microscopy and x-ray diffraction experiments indicate that the relaxation rate of the lattice mismatch stress increases with the growth temperature but finally results in a higher dislocations density. Furthermore, a general trend appears between the final wafer curvature at room temperature and the threading dislocation density. Finally, the influence of the dislocation density on the GaN buffer insulating properties and the two-dimensional electron gas transport properties at the Al{sub x}Ga{sub 1-x}N/GaN interface is discussed.

Baron, N. [CRHEA-CNRS, rue Bernard Gregory, Parc de Sophia Antipolis, 06560 Valbonne (France); PICOGIGA International, Place Marcel Rebuffat, Parc de Villejust, 91971 Courtaboeuf (France); Cordier, Y.; Chenot, S.; Vennegues, P.; Tottereau, O.; Leroux, M.; Semond, F.; Massies, J. [CRHEA-CNRS, rue Bernard Gregory, Parc de Sophia Antipolis, 06560 Valbonne (France)

2009-02-01T23:59:59.000Z

322

Wafer Bonding and Epitaxial Transfer of GaSb-based Epitaxy to GaAs for Monolithic Interconnection of Thermophotovoltaic Devices  

SciTech Connect (OSTI)

GaInAsSb/AlGaAsSb/InAsSb/GaSb epitaxial layers were bonded to semi-insulating GaAs handle wafers with SiO{sub x}/Ti/Au as the adhesion layer for monolithic interconnection of thermophotovoltaic (TPV) devices. Epitaxial transfer was completed by removal of the GaSb substrate, GaSb buffer, and InAsSb etch-stop layer by selective chemical etching. The SiO{sub x}/TiAu provides not only electrical isolation, but also high reflectivity and is used as an internal back-surface reflector. Characterization of wafer-bonded epitaxy by high-resolution x-ray diffraction and time-decay photoluminescence indicates minimal residual stress and enhancement in optical quality. 0.54-eV GaInAsSb cells were fabricated and monolithically interconnected in series. A 10-junction device exhibited linear voltage building with an open-circuit voltage of 1.8 V.

C.A. Wang; D.A. Shiau; P.G. Murphy; P.W. O'brien; R.K. Huang; M.K. Connors; A.C. Anderson; D. Donetsky; S. Anikeev; G. Belenky; D.M. Depoy; G. Nichols

2003-06-16T23:59:59.000Z

323

Long wavelength emitting GaInN quantum wells on metamorphic GaInN buffer layers with enlarged in-plane lattice parameter  

SciTech Connect (OSTI)

Metamorphic (i.e., linear composition graded) GaInN buffer layers with an increased in-plane lattice parameter, grown by plasma-assisted molecular beam epitaxy, were used as templates for metal organic vapor phase epitaxy (MOVPE) grown GaInN/GaInN quantum wells (QWs), emitting in the green to red spectral region. A composition pulling effect was observed allowing considerable higher growth temperatures for the QWs for a given In composition. The internal quantum efficiency (IQE) of the QWs was determined by temperature and excitation power density dependent photoluminescence (PL) spectroscopy. An increase in IQE by a factor of two was found for green emitting QWs grown on metamorphic GaInN buffer compared to reference samples grown on standard GaN buffer layers. The ratio of room temperature to low temperature intensity PL of the red emitting QWs were found to be comparable to the PL efficiency of green emitting QWs, both grown on metamorphic GaInN buffers. The excitation density and well width dependence of the IQE indicate a reduction of the quantum confined Stark effect upon growth on GaInN buffer layers with increased in-plane lattice parameter.

Dubler, J., E-mail: juergen.daeubler@iaf.fraunhofer.de; Passow, T.; Aidam, R.; Khler, K.; Kirste, L.; Kunzer, M.; Wagner, J. [Fraunhofer-Institut fr Angewandte Festkrperphysik, Tullastrasse 72, 79108 Freiburg (Germany)

2014-09-15T23:59:59.000Z

324

High-temperature luminescence in an n-GaSb/n-InGaAsSb/p-AlGaAsSb light-emitting heterostructure with a high potential barrier  

SciTech Connect (OSTI)

The electroluminescent properties of an n-GaSb/n-InGaAsSb/p-AlGaAsSb heterostructure with a high potential barrier in the conduction band (large conduction-band offset) at the n-GaSb/n-InGaAsSb type-II heterointerface ({Delta}E{sub c} = 0.79 eV) are studied. Two bands with peaks at 0.28 and 0.64 eV at 300 K, associated with radiative recombination in n-InGaAsSb and n-GaSb, respectively, are observed in the electroluminescence (EL) spectrum. In the entire temperature range under study, T = 290-480 K, additional electron-hole pairs are formed in the n-InGaAsSb active region by impact ionization with hot electrons heated as a result of the conduction-band offset. These pairs contribute to radiative recombination, which leads to a nonlinear increase in the EL intensity and output optical power with increasing pump current. A superlinear increase in the emission power of the long-wavelength band is observed upon heating in the temperature range T = 290-345 K, and a linear increase is observed at T > 345 K. This work for the first time reports an increase in the emission power of a light-emitting diode structure with increasing temperature. It is shown that this rise is caused by a decrease in the threshold energy of the impact ionization due to narrowing of the band gap of the active region.

Petukhov, A. A., E-mail: andrey-rus29@rambler.ru; Zhurtanov, B. E.; Kalinina, K. V.; Stoyanov, N. D.; Salikhov, H. M.; Mikhailova, M. P.; Yakovlev, Yu. P. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)] [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

2013-09-15T23:59:59.000Z

325

Origin of InGaN/GaN light-emitting diode efficiency improvements using tunnel-junction-cascaded active regions  

SciTech Connect (OSTI)

This Letter investigates the efficiency enhancement achieved by tunnel junction insertion into the InGaN/GaN multi-quantum well (MQW) active region of blue light emitting diodes (LEDs). The peak quantum efficiency of such LED exceeds 100%, but the maximum wall-plug efficiency (WPE) hardly changes. However, due to the increased bias, the WPE peaks at much higher input power, i.e., the WPE droop is significantly delayed, and the output power is strongly enhanced. The main physical reason for this improvement lies in the non-uniform vertical carrier distribution typically observed within InGaN MQWs.

Piprek, Joachim, E-mail: piprek@nusod.org [NUSOD Institute LLC, P.O. Box 7204, Newark, Delaware 19714 (United States)

2014-02-03T23:59:59.000Z

326

Magnetic properties of Ga doped cobalt ferrite: Compton scattering study  

SciTech Connect (OSTI)

We present the spin momentum density of Ga doped CoFe{sub 2}O{sub 4} at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe{sub 2}O{sub 4}.

Sharma, Arvind, E-mail: arvind.phd.swm@gmail.com; Mund, H. S.; Ahuja, B. L. [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur-313001 (India); Sahariya, Jagrati [Department of Physics, Manipal University, Jaipur-303007 (India); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

2014-04-24T23:59:59.000Z

327

Structure, transport and thermal properties of UCoGa  

SciTech Connect (OSTI)

By means of neutron powder diffraction, we find that UCoGa crystallizes in the hexagonal ZrNiAl structure and orders ferromagnetically at low temperatures with magnetic moments stacked along the c axis. The magnetic-ordering temperature is reflected in anomalies in the temperature dependencies of the electrical resistivity and the specific heat at Tc = 47 K. Furthermore, the strong anisotropy in the electrical resistivity for i {parallel} c and i {perpendicular} c indicates a significant contribution of the magnetic anisotropy to the electrical resistivity.

Purwanto, A.; Robinson, R.A. [Los Alamos National Lab., NM (United States); Prokes, K. [Amsterdam Univ. (Netherlands). Van der Waals Lab.] [and others

1994-04-01T23:59:59.000Z

328

Low dimensional GaAs/air vertical microcavity lasers  

SciTech Connect (OSTI)

We report on the fabrication of gallium arsenide (GaAs)/air distributed Bragg reflector microresonators with indium gallium arsenide quantum wells. The structures are studied via momentum resolved photoluminescence spectroscopy which allows us to investigate a pronounced optical mode quantization of the photonic dispersion. We can extract a length parameter from these quantized states whose upper limit can be connected to the lateral physical extension of the microcavity via analytical calculations. Laser emission from our microcavity under optical pumping is observed in power dependent investigations.

Gessler, J.; Steinl, T.; Fischer, J.; Hfling, S.; Schneider, C.; Kamp, M. [Technische Physik, Physikalisches Institut and Wilhelm Conrad Rntgen-Research Center for Complex Material Systems, Universitt Wrzburg, Am Hubland, D-97074 Wrzburg (Germany); Mika, A.; S?k, G.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wybrze?e Wyspia?skiego 27, 50-370 Wroc?aw (Poland)

2014-02-24T23:59:59.000Z

329

Quantum effects in electron beam pumped GaAs  

SciTech Connect (OSTI)

Propagation of waves in nano-sized GaAs semiconductor induced by electron beam are investigated. A dispersion relation is derived by using quantum hydrodynamics equations including the electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures. It is found that the propagating modes are instable and strongly depend on the electron beam parameters, as well as the quantum recoil effects and degenerate pressures. The instability region shrinks with the increase of the semiconductor number density. The instability arises because of the energetic electron beam produces electron-hole pairs, which do not keep in phase with the electrostatic potential arising from the pair plasma.

Yahia, M. E. [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt) [Faculty of Engineering, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Azzouz, I. M. [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt)] [National Institute of Laser Enhanced Sciences (NILES), Cairo University (Egypt); Moslem, W. M. [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)] [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt)

2013-08-19T23:59:59.000Z

330

Defect studies in ion irradiated AlGaN. | EMSL  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation Proposed Newcatalyst phasesData Files Data Files 1B&W Y-12studies in ion irradiated AlGaN.

331

Dynamic nuclear polarization and Hanle effect in (In,Ga)As/GaAs quantum dots. Role of nuclear spin fluctuations  

SciTech Connect (OSTI)

The degree of circular polarization of photoluminescence of (In,Ga)As quantum dots as a function of magnetic field applied perpendicular to the optical axis (Hanle effect) is experimentally studied. The measurements have been performed at various regimes of the optical excitation modulation. The analysis of experimental data has been performed in the framework of a vector model of regular nuclear spin polarization and its fluctuations. The analysis allowed us to evaluate the magnitude of nuclear polarization and its dynamics at the experimental conditions used.

Gerlovin, I. Ya. [Spin Optics Laboratory, Saint Petersburg State University, Petrodvorets, 198504 St. Petersburg (Russian Federation); Cherbunin, R. V.; Ignatiev, I. V.; Kuznetsova, M. S.; Verbin, S. Yu. [Spin Optics Laboratory, Saint Petersburg State University, Petrodvorets, 198504 St. Petersburg, Russia and Experimentelle Physik 2, Technische Universitt Dortmund, D-44221 Dortmund (Germany); Flisinski, K.; Bayer, M. [Experimentelle Physik 2, Technische Universitt Dortmund, D-44221 Dortmund (Germany); Reuter, D.; Wieck, A. D. [Angewandte Festkrperphysik, Ruhr-Universitt Bochum, D-44780 Bochum (Germany); Yakovlev, D. R. [Experimentelle Physik 2, Technische Universitt Dortmund, D-44221 Dortmund, Germany and A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

2013-12-04T23:59:59.000Z

332

Ga-doped ZnO grown by pulsed laser deposition in H2: the roles of Ga and H.  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFun with Big Sky Learning Fun with Big SkyDIII-DRMR LSU/CAMD| EMSL Ga-doped

333

Evanescent-wave pumped room-temperature single-mode GaAs/AlGaAs core-shell nanowire lasers  

SciTech Connect (OSTI)

Evanescent-wave pumped room-temperature single-mode GaAs/AlGaAs core-shell nanowire lasers are proposed and demonstrated. The nanowires are axially excited by evanescent wave outside a microfiber with a diameter about 10??m via a ns-pulse laser. The lasing emission with a low effective threshold less than 90 nJ is achieved at 868.62?nm along with a linewidth of ?1.8?nm. Moreover, multiple lasing lines in a wavelength range from 852.56?nm to 882.48?nm are observed. The mechanism of diverse lasing wavelengths is revealed. Furthermore, the proposed GaAs/AlGaAs nanowire laser has advantages such as simple structure, easy to operate, and controllable lasing wavelength, tending to be practical in optical communications and integrated photonic circuits.

Wei, Wei; Zhang, Xia, E-mail: xzhang@bupt.edu.cn; Ren, Xiaomin [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, P.O. Box 66, Beijing 100876 (China); Liu, Yange, E-mail: ygliu@nankai.edu.cn; Wang, Zhi [Key Laboratory of Optical Information and Technology, Ministry of Education and Institute of Modern Optics, Nankai University, Tianjin 300071 (China)

2014-06-02T23:59:59.000Z

334

Effects of capping on GaN quantum dots deposited on Al{sub 0.5}Ga{sub 0.5}N by molecular beam epitaxy  

SciTech Connect (OSTI)

The impact of the capping process on the structural and morphological properties of GaN quantum dots (QDs) grown on fully relaxed Al{sub 0.5}Ga{sub 0.5}N templates was studied by transmission electron microscopy. A morphological transition between the surface QDs, which have a pyramidal shape, and the buried ones, which have a truncated pyramid shape, is evidenced. This shape evolution is accompanied by a volume change: buried QDs are bigger than surface ones. Furthermore a phase separation into Al{sub 0.5}Ga{sub 0.5}N barriers was observed in the close vicinity of buried QDs. As a result, the buried QDs were found to be connected with the nearest neighbors by thin Ga-rich zones, whereas Al-rich zones are situated above the QDs.

Korytov, M. [CRHEA-CNRS, rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France) and University of Nice Sophia-Antipolis, Parc Valrose, 06103 Nice (France); Benaissa, M. [CNRST, angle Allal-Fassi/FAR, Madinat al-irfane, 10000 Rabat (Morocco); Brault, J.; Vennegues, P. [CRHEA-CNRS, rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Huault, T. [CRHEA-CNRS, rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne, France and RIBER S.A., 31 rue Casimir Perier, BP 70083, 95873 Bezons Cedex (France); Neisius, T. [CP2M, Faculte Saint Jerome, 13397 Marseille Cedex 20 (France)

2009-04-06T23:59:59.000Z

335

Molecular-beam epitaxial growth and characterization of inverted, pulse-doped AlGaAs/InGaAs transistor structures  

SciTech Connect (OSTI)

Inverted, pulse-doped AlGaAs/InGaAs pseudomorphic high electron mobility transistor structures were grown by molecular-beam epitaxy. Growth conditions were optimized to improve the quality of the selectively doped AlGaAs layer and to minimize dopant diffusion into the InGaAs channel. The sheet densities and mobilities of the inverted structure were found to be essentially equivalent to those obtained with the normal structure. Shubnikov-de Haas measurements exhibited strong oscillations in the magnetoresistance and plateaus in the Hall resistance. Four optical transitions from the lowest bound electron and hole quantum well states were observed in room-temperature photoluminescence spectra. 15 refs., 4 figs.

Hoke, W.E.; Lyman, P.S.; Brierley, S.K. [Raytheon Research Division, Lexington, MA (United States)] [and others] [Raytheon Research Division, Lexington, MA (United States); and others

1993-05-01T23:59:59.000Z

336

The Effect of Offcut Angle on Electrical Conductivity of Direct Wafer-Bonded n-GaAs/n-GaAs Structures for Wafer-Bonded Tandem Solar Cells  

E-Print Network [OSTI]

Efficiency of p?n Junction Solar Cells, J. Appl. Phys. 32,Inverted Triple- Junction Solar Cell with Two Independentlyof Thin-Film GaAs Solar Cells on Si Substrates, J. Appl.

Yeung, King Wah Sunny

2012-01-01T23:59:59.000Z

337

The use of short-period InGaN/GaN superlattices in blue-region light-emitting diodes  

SciTech Connect (OSTI)

Optical and light-emitting diode structures with an active InGaN region containing short-period InGaN/GaN superlattices are studied. It is shown that short-period superlattices are thin two-dimensional layers with a relatively low In content that contain inclusions with a high In content 1-3 nm thick. Inclusions manifest themselves from the point of view of optical properties as a nonuniform array of quantum dots involved in a residual quantum well. The use of short-period superlattices in light-emitting diode structures allows one to decrease the concentration of nonradiative centers, as well as to increase the injection of carriers in the active region due to an increase in the effective height of the AlGaN barrier, which in general leads to an increase in the quantum efficiency of light-emitting diodes.

Sizov, V. S., E-mail: vsizov@mail.ioffe.ru; Tsatsulnikov, A. F.; Sakharov, A. V.; Lundin, W. V.; Zavarin, E. E.; Cherkashin, N. A. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Hytch, M. J. [National Center for Scientific Research (CNRS), Center for Material Elaboration and Structural Studies (CEMES) (France); Nikolaev, A. E. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Mintairov, A. M.; He Yan; Merz, J. L. [University of Notre Dame, EE Department (United States)

2010-07-15T23:59:59.000Z

338

2=picosecond, GaAs photodiode optoelectronic circuit for optical correlation applications  

E-Print Network [OSTI]

2=picosecond, GaAs photodiode optoelectronic circuit for optical correlation applications K. D. Li GaAs Schottky photodiode is monolithically integrated with a microwave detector. By using this new optoelectronic circuit.in place of a nonlinear crystal in an optical correlation setup, the high-speed photodiode

Ozbay, Ekmel

339

Ultralow noise midwave infrared InAsGaSb strain layer superlattice avalanche photodiode  

E-Print Network [OSTI]

Ultralow noise midwave infrared InAs­GaSb strain layer superlattice avalanche photodiode InAs­GaSb strain layer superlattice p+ -n- -n homojunction avalanche photodiodes APDs grown by solid characteristics. © 2007 American Institute of Physics. DOI: 10.1063/1.2817608 Photodiodes operating in the eye

Krishna, Sanjay

340

14 MHz rate photon counting with room temperature InGaAs/InP avalanche photodiodes  

E-Print Network [OSTI]

14 MHz rate photon counting with room temperature InGaAs/InP avalanche photodiodes PAUL L. VOSS based on InGaAs/InP avalanche photodiodes for use at 1.55 mm wavelength. Operation at room temperature at the above wavelengths for conventional high light-level measurements with PIN or ava- lanche photodiodes

Köprülü, Kahraman Güçlü

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells  

E-Print Network [OSTI]

Diffusion of indium and gallium in Cu(In,Ga)Se2 thin film solar cells O. Lundberga,*, J. Lua , A. Rockettb , M. Edoffa , L. Stolta a A°ngstro¨m Solar Center, Uppsala University, P.O. Box 534, SE-751 21 Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been

Rockett, Angus

342

Hybrid GA-SA Algorithms for Reducing Energy Consumption in Embedded Systems  

E-Print Network [OSTI]

Hybrid GA-SA Algorithms for Reducing Energy Consumption in Embedded Systems Maha IDRISSI AOUAD Vandoeuvre-L`es-Nancy, France. Email: Rene.Schott@loria.fr Abstract--Reducing energy consumption in embedded algorithms based on Simulated An- nealing (SA) and Genetic Algorithm (GA) for reducing energy consumption

Schott, René - Institut de Mathématiques ?lie Cartan, Université Henri Poincaré

343

Fermi Level Control of Point Defects During Growth of Mg-Doped GaN  

E-Print Network [OSTI]

, and photodetectors have been developed, but the optical transitions in GaN:Mg are still not well under- stood.2 Mg.1007/s11664-012-2342-9 ? 2012 TMS #12;irradiation during growth affected the material, but the nature demonstrate point defect control in Mg-doped GaN, by UV irradiation during growth. First, details

Nabben, Reinhard

344

Photorefractive measurements in electron irradiated semi-insulating GaAs  

E-Print Network [OSTI]

. The native and irradiation induced defects have been assessed by electron paramagnetic resonance and optical irradiation induced defects in GaAs, we present results of electron paramagnetic resonance (EPR) and optical1 Photorefractive measurements in electron irradiated semi-insulating GaAs P. Delaye(1), H.J. von

345

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission  

E-Print Network [OSTI]

ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission angle Emily D Kosten1 solar cell under direct sunlight, light is received from the solar disk, but is re-emitted isotropically.1038/lsa.2013.1; published online 4 January 2013 Keywords: detailed balance; GaAs solar cell; light

Atwater, Harry

346

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells Keisuke Nakayama,a  

E-Print Network [OSTI]

Plasmonic nanoparticle enhanced light absorption in GaAs solar cells Keisuke Nakayama,a Katsuaki 22 September 2008 We demonstrate an improvement in efficiency of optically thin GaAs solar cells-ratio nanoparticles effectively increases the optical path of the incident light in the absorber layers resulting

Atwater, Harry

347

High efficiency light emitting diode with anisotropically etched GaN-sapphire interface  

E-Print Network [OSTI]

High efficiency light emitting diode with anisotropically etched GaN- sapphire interface M. H. Lo and optimization of a light-emitting diode projection micro-stereolithography three-dimensional manufacturingGaN micro-light emitting diodes Appl. Phys. Lett. 101, 231110 (2012) A bright cadmium-free, hybrid organic

348

Electrical gating effects on the magnetic properties of (Ga,Mn)As diluted magnetic semiconductors  

E-Print Network [OSTI]

-effect transistor (FET) based on low-doped Ga0.975Mn0.025As was fabricated. It has an in-built n-GaAs back-gate, which, in addition to being a normal gate, enhances the gating effects, especially in the depletion of the epilayer, by decreasing the effective channel...

Owen, Man Hon Samuel

2010-11-16T23:59:59.000Z

349

Coupling of nitrogen-vacancy centers in diamond to a GaP waveguide  

E-Print Network [OSTI]

The optical coupling of guided modes in a GaP waveguide to nitrogen-vacancy (NV) centers in diamond is demonstrated. The electric field penetration into diamond and the loss of the guided mode are measured. The results indicate that the GaP-diamond system could be useful for realizing coupled microcavity-NV devices for quantum information processing in diamond.

K. -M. C. Fu; C. Santori; P. E. Barclay; I. Aharonovich; S. Prawer; N. Meyer; A. M. Holm; R. G. Beausoleil

2008-11-03T23:59:59.000Z

350

NANO EXPRESS Open Access Selective area epitaxy of ultra-high density InGaN  

E-Print Network [OSTI]

annealing and GaN spacer layer growth for improving the PL intensity of the SiNx-treated GaN surface in three dimensions for QD nanostructures so that the non-radiative recom- bination centers and defects can

Gilchrist, James F.

351

(a) p contact p-lnGaAs --p-lnP cladding  

E-Print Network [OSTI]

of different dimensions and/or materials have to be aligned to sub- micron precision to enable efficient (PL:1545 nm) Spacer Super lattice Bonding layer 1 .7Q-AI0055Ga0292In0653As (8x) nP 1.1 Q-1n085Ga0 5As

Bowers, John

352

Nanometer-scale InGaAs Field-Effect Transistors for THz and CMOS technologies  

E-Print Network [OSTI]

prospect is generating is also reinvigorating the prospects of InGaAs FETs to become the first true THz. While the markets are not very large, significant commercial applications exist. At the frontiers represents a breakthrough that opens new avenues for InGaAs to reach the THz frontier. Possible future THz In

del Alamo, Jesús A.

353

Analyzing the Performance of a Multiobjective GA-P Algorithm for Learning Fuzzy Queries in  

E-Print Network [OSTI]

Analyzing the Performance of a Multiobjective GA-P Algorithm for Learning Fuzzy Queries in a Machine Learning Environment Oscar Cord´on1 , Enrique Herrera-Viedma1 , Mar´ia Luque1 , F´elix de Moya2- tionary algorithms (EAs) [1], such as genetic algorithm-programming (GA-P) [11] or simulated annealing

Fernandez, Thomas

354

Development of a Low Cost Insulated Foil Substrate for Cu(InGaSe)2 Photovoltaics  

SciTech Connect (OSTI)

The project validated the use of stainless steel flexible substrate coated with silicone-based resin dielectric, developed by Dow Corning Corporation, for Cu(InGa)Se2 based photovoltaics. The projects driving force was the high performance of Cu(InGa)Se2 based photovoltaics coupled with potential cost reduction that could be achieved with dielectric coated SS web substrate.

ERTEN ESER

2012-01-22T23:59:59.000Z

355

In situ chemical sensing in AlGaN/GaN high electron mobility transistor metalorganic chemical vapor deposition process for real-time  

E-Print Network [OSTI]

; accepted 14 June 2005; published 18 July 2005 Gallium nitride and its alloys promise to be key materials.1116/1.1993616 I. INTRODUCTION In recent years, gallium-nitride GaN - and aluminum- gallium-nitride AlGaN -based are grown at high temperatures e.g., up to 1100 °C using large concentrations of H2 carrier and NH3 N source

Rubloff, Gary W.

356

IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 42, NO. 4, APRIL 2006 397 Design and Performance of an InGaAsInP  

E-Print Network [OSTI]

, focusing on the effect of the critical InGaAsP grading layer between the narrow-gap InGaAs absorption layer

Buller, Gerald S.

357

Critical size for the generation of misfit dislocations and their effects on electronic properties in GaAs nanosheets on Si substrate  

E-Print Network [OSTI]

-Queisser limit6 for the solar-cell efficiency. Recently, NWs of various semi- conductors such as GaAs/AlGaAs,7

Southern California, University of

358

Evolution Of Surface Topography On GaAs(100) And GaAs(111) At Normal And Oblique Incidence Of Ar{sup +}-Ions  

SciTech Connect (OSTI)

Nanoscale surface structures emerging from medium energy (50-60 keV)Ar{sup +}-ion sputtering of p-type GaAs(100) and semi-insulating GaAs(111) substrates have been investigated. For normally incident 50 keV Ar{sup +}-ions of fluence 1x10{sup 17} ions/cm{sup 2} on GaAs(100) and GaAs(111) features in the form of nanoscale pits/holes without short range ordering are observed with densities 5.2x10{sup 9} /cm{sup 2} and 5.9x10{sup 9} /cm{sup 2}, respectively along with irregularly shaped patches of islands. For GaAs(111) on increasing the influence to 5x10{sup 17} /cm{sup 2} the pit density increases marginally to 6.2x10{sup 9} /cm{sup 2}. For 60 deg. off-normal incidence of 60 keV Ar.{sup +}-ions of fluence 2x10{sup 17} ions/cm{sup 2} on GaAs(100) microscale wavelike surface topography is observed. In all cases well-defined nanodots are absent on the surface.

Venugopal, V.; Basu, T.; Garg, S.; Majumder, S.; Sarangi, S. N.; Som, T. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751 005 (India); Das, P.; Bhattacharyya, S. R.; Chini, T. K. [Surface Physics Division, Saha Institute of Nuclear Physics, Kolkata 700 064 (India)

2010-10-04T23:59:59.000Z

359

Photoreflectance and reflectance investigation of deuterium-irradiated GaAsN  

SciTech Connect (OSTI)

The effect of deuterium irradiation on the optical and strain properties of GaAsN/GaAs heterostructures was investigated by photoreflectance and reflectance techniques. The strain occurring in as-grown and deuterated GaAsN layers is monitored and measured by means of photoreflectance spectroscopy, highlighting the strain inversion after irradiation. By combining static and modulated reflectance results, evidence is given that the deuterium-induced recovery of the GaAs band gap as well as the strain inversion in GaAsN layers are accompanied by a 0.4%-0.8% reduction of the refractive index in the 1.31 and 1.55 {mu}m spectral windows of interest for fiber optic communications. These results anticipate a single step process to an in-plane confinement of carriers and photons.

Geddo, M.; Ciabattoni, T.; Guizzetti, G.; Galli, M.; Patrini, M.; Polimeni, A.; Trotta, R.; Capizzi, M.; Bais, G.; Piccin, M.; Rubini, S.; Martelli, F.; Franciosi, A. [CNISM-Dipartimento di Fisica Universita di Parma, Viale delle Scienze 7a, I-43100 Parma (Italy); CNISM-Dipartimento di Fisica 'A. Volta', Universita di Pavia, Via Bassi 6, I-27100 Pavia (Italy); CNISM-Dipartimento di Fisica, Universita 'La Sapienza', P.le A. Moro 2, 00185 Rome (Italy); Laboratorio Nazionale TASC-INFM-CNR, Area Science Park, S.S. 14, Km. 163.5, 34012 Trieste (Italy)

2007-02-26T23:59:59.000Z

360

Enhanced photoelectrochemical responses of ZnO films through Ga and N codoping  

SciTech Connect (OSTI)

We report on the crystallinity and photoelectrochemical (PEC) response of ZnO thin films codoped by Ga and N. The ZnO:(Ga,N) thin films were deposited by cosputtering at room temperature and followed by postannealing at 500 deg. C in air for 2 h. We found that ZnO:(Ga,N) thin films exhibited significantly enhanced crystallinity compared to ZnO doped solely with N at the same growth conditions. Furthermore, ZnO:(Ga,N) thin films exhibited enhanced N incorporation over ZnO doped solely with N at high temperatures. As a result, ZnO:(Ga,N) thin films achieved dramatically improved PEC response, compared to ZnO thin films doped solely with N at any conditions. Our results suggest a general way to improve PEC response for wide-band-gap oxides.

Ahn, Kwang-Soon; Yan, Yanfa; Shet, Sudhakar; Deutsch, Todd; Turner, John; Al-Jassim, Mowafak [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

2007-12-03T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Many-body effects on optical gain in GaAsPN/GaPN quantum well lasers for silicon integration  

SciTech Connect (OSTI)

Many-body effects on the optical gain in GaAsPN/GaP QW structures were investigated by using the multiband effective-mass theory and the non-Markovian gain model with many-body effects. The free-carrier model shows that the optical gain peak slightly increases with increasing N composition. In addition, the QW structure with a larger As composition shows a larger optical gain than that with a smaller As composition. On the other hand, in the case of the many-body model, the optical gain peak decreases with increasing N composition. Also, the QW structure with a smaller As composition is observed to have a larger optical gain than that with a larger As composition. This can be explained by the fact that the QW structure with a smaller As or N composition shows a larger Coulomb enhancement effect than that with a larger As or N composition. This means that it is important to consider the many-body effect in obtaining guidelines for device design issues.

Park, Seoung-Hwan, E-mail: shpark@cu.ac.kr [Department of Electronics Engineering, Catholic University of Daegu, Hayang, Kyeongbuk 712-702 (Korea, Republic of)

2014-02-14T23:59:59.000Z

362

Photodiode characteristics and band alignment parameters of epitaxial Al0.5Ga0.5P  

E-Print Network [OSTI]

Photodiode characteristics and band alignment parameters of epitaxial Al0.5Ga0.5P An Chen1,a-bandgap semiconductor AlxGa1-xP is a promising material candidate for low-noise photodiodes in blue/UV spectrum. Photodiodes were fabricated on Al0.5Ga0.5P epitaxial layer grown lattice matched on GaP substrate by molecular

Woodall, Jerry M.

363

Effect of Trapping on the Critical Voltage for Degradation in GaN High Electron Mobility Transistors  

E-Print Network [OSTI]

conditions, UV illumination decreases the critical voltage for the onset of degradation in gate current in Ga traps in the fresh state. Keywords­ GaN HEMTs, critical voltage, degradation, UV illuminationEffect of Trapping on the Critical Voltage for Degradation in GaN High Electron Mobility

del Alamo, Jesús A.

364

Strain relaxation of thick (1122) semipolar InGaN layer for long wavelength nitride-based device  

SciTech Connect (OSTI)

In this study, the properties of thick stress-relaxed (1122) semipolar InGaN layers were investigated. Owing to the inclination of growth orientation, misfit dislocations (MDs) occurred at the heterointerface when the strain state of the (1122) semipolar InGaN layers reached the critical point. We found that unlike InGaN layers based on polar and nonpolar growth orientations, the surface morphologies of the stress-relaxed (1122) semipolar InGaN layers did not differ from each other and were similar to the morphology of the underlying GaN layer. In addition, misfit strain across the whole InGaN layer was gradually relaxed by MD formation at the heterointerface. To minimize the effect of surface roughness and defects in GaN layers on the InGaN layer, we conducted further investigation on a thick (1122) semipolar InGaN layer grown on an epitaxial lateral overgrown GaN template. We found that the lateral indium composition across the whole stress-relaxed InGaN layer was almost uniform. Therefore, thick stress-relaxed (1122) semipolar InGaN layers are suitable candidates for use as underlying layers in long-wavelength devices, as they can be used to control strain accumulation in the heterostructure active region without additional influence of surface roughness.

Kim, Jaehwan; Min, Daehong; Jang, Jongjin; Lee, Kyuseung; Chae, Sooryong; Nam, Okhyun, E-mail: ohnam@kpu.ac.kr [Advanced Photonics Research Center/LED Technology Center, Department of Nano-Optical Engineering, Korea Polytechnic University, 237, Sangidaehak-ro, Siheung-si, Gyeonggi-do 429-793 (Korea, Republic of)

2014-10-28T23:59:59.000Z

365

Junction temperature, spectral shift, and efficiency in GaInN-based blue and green light emitting diodes  

E-Print Network [OSTI]

Keywords: GaInN/GaN Light emitting diode temperature Micro-Raman Photoluminescence Electroluminescence well light emitting diode (LED) dies is analyzed by micro-Raman, photoluminescence, cathodoluminescenceJunction temperature, spectral shift, and efficiency in GaInN-based blue and green light emitting

Wetzel, Christian M.

366

Intrinsic vacancy induced nanoscale wire structure in heteroepitaxial Ga2Se3/Si(001) Taisuke Ohta,1,  

E-Print Network [OSTI]

Intrinsic vacancy induced nanoscale wire structure in heteroepitaxial Ga2Se3/Si(001) Taisuke Ohta,1-blende structure of -Ga2Se3, which contains ordered 110 arrays of Ga vacancies. These ordered vacancy lines structural vacancies of semiconducting chalcogenides lead to numerous interesting structural, electronic

Olmstead, Marjorie

367

Band gap tuning in GaN through equibiaxial in-plane strains S. K. Yadav,2  

E-Print Network [OSTI]

in photovoltaics and light emission diodes LEDs . The InGaN system has been intensively studied during the past to the large atomic size mismatch between Ga and In.3 Thus, other methods to tune the band gap are needed for potential appli- cations of GaN and related materials systems. It is well-known that the structure

Alpay, S. Pamir

368

Cr-Ga-N materials for negative electrodes in Li rechargeable batteries : structure, synthesis and electrochemical performance  

E-Print Network [OSTI]

Electrochemical performances of two ternary compounds (Cr2GaN and Cr3GaN) in the Cr-Ga-N system as possible future anode materials for lithium rechargeable batteries were studied. Motivation for this study was dealt in ...

Kim, Miso

2007-01-01T23:59:59.000Z

369

Low-temperature magnetization of (Ga,Mn) As semiconductors  

E-Print Network [OSTI]

of the Zeeman Hamil- tonian gS#3;BBS?z+gj#3;BBj?z, and from Eq. #1;1#2;: m ? mMF #14; mQF = ? #3;B j S + j #1;gS ? gj#2; . #1;5#2; When j=1/2 and gS=gj =2 the quantum fluctuation correc- tion to the magnetization vanishes even though the mean- field...Low-temperature magnetization of (Ga,Mn)As semiconductors T. Jungwirth,1,2 J. Ma?ek,3 K. Y. Wang,2 K. W. Edmonds,2 M. Sawicki,4 M. Polini,5 Jairo Sinova,6 A. H. MacDonald,7 R. P. Campion,2,8 L. X. Zhao,2,8 N. R. S. Farley,2,8 T. K. Johal,8 G. van...

Jungwirth, T.; Masek, J.; Wang, KY; Edmonds, KW; Sawicki, M.; Polini, M.; Sinova, Jairo; MacDonald, AH; Campion, RP; Zhao, LX; Farley, NRS; Johal, TK; van der Laan, G.; Foxon, CT; Gallagher, BL.

2006-01-01T23:59:59.000Z

370

Dimensionality of InGaAs nonlinear optical response  

SciTech Connect (OSTI)

In this thesis the ultrafast optical properties of a series of InGaAs samples ranging from the two to the three dimensional limit are discussed. An optical system producing 150 fs continuum centered at 1.5 microns was built. Using this system, ultrafast pump-probe and four wave mixing experiments were performed. Carrier thermalization measurements reveal that screening of the Coulomb interaction is relatively unaffected by confinement, while Pauli blocking nonlinearities at the band edge are approximately twice as strong in two dimensions as in three. Carrier cooling via phonon emission is influenced by confinement due both to the change in electron distribution function and the reduction in electron phonon coupling. Purely coherent band edge effects, as measured by the AC Stark effect and four wave mixing, are found to be dominated by the changes in excitonic structure which take place with confinement.

Bolton, S.R. [Univ. of California, Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley National Lab., CA (United States). Materials Sciences Div.

1995-07-01T23:59:59.000Z

371

26. 1% solar cell efficiency for Ge mechanically stacked under GaAs  

SciTech Connect (OSTI)

We have processed a diffused Ge wafer into a Ge concentrator solar cell and mechanically stacked it under a GaAs cell fabricated by Varian. We measured this stack's efficiency to be 26.1% for terrestrial air mass 1.5 direct (AM1.5D) conditions at a 285 x concentration ratio. We showed that this efficiency is limited by optical absorption in the Varian GaAs cell caused by high 2--4 (10/sup 18/) cm/sup -3/ substrate doping. We used a 2 x 10/sup 17/ cm/sup -3/ doped GaAs filter to estimate the stack efficiency as 27.4%, which would be achieved with the same Varian GaAs cell formed on a lower doped substrate. We project efficiencies assuming the best properties reported for a GaAs device. This gives a 29.6% efficiency for an improved, planar Ge cell and 31.6% efficiency for a proposed point contact geometry for the Ge cell. The corresponding space (AM0) efficiencies at a 159 x concentration ratio range from the 23.4% value we measured on the stack up to 28.4% projected for the point contact Ge place under the best GaAs cell. We showed that Ge cells give higher efficiencies than Si when stacked under GaAs.

Partain, L.D.; Kuryla, M.S.; Weiss, R.E.; Ransom, R.A.; McLeod, P.S.; Fraas, L.M.; Cape, J.A.

1987-10-01T23:59:59.000Z

372

Large interface diffusion in endotaxial growth of MnP films on GaP substrates  

SciTech Connect (OSTI)

The metal organic vapor deposition of MnP films on GaP (100) substrates is shown to have a substantial endotaxial component. A study of the growth time evolution of the endotaxial depths of MnP grains reveals a diffusion-controlled growth with a relatively large diffusion coefficient of Mn in GaP. The value (2.2??1.5)??10{sup ?15} (cm{sup 2}/s) obtained at 650?C is at least two orders of magnitude larger than the reported Mn diffusion in bulk GaP. GaP surface mounds provide further indirect evidence that this large diffusion coefficient is concurrent with the out-diffusion of Ga atoms at the growing MnP/GaP interface. No trace of dislocations could be observed at or near this interface, which strongly suggests that Mn diffusion occurs through vacant sites generated by the difference between the crystallographic structures of MnP and GaP.

Nateghi, N., E-mail: seyyed-nima.nateghi@polymtl.ca; Mnard, D.; Masut, R. A. [Regroupement qubcoise sur les matriaux de pointe (RQMP), Dpartement de Gnie Physique, Polytechnique Montral, C.P. 6079, succ. Centre-ville, Montral, Qubec H3C 3A7 (Canada)

2014-10-07T23:59:59.000Z

373

Intersubband transitions in In{sub x}Ga{sub 1?x}N/In{sub y}Ga{sub 1?y}N/GaN staggered quantum wells  

SciTech Connect (OSTI)

Intersubband transition energies and absorption lineshape in staggered InGaN/GaN quantum wells surrounded by GaN barriers are computed as functions of structural parameters such as well width, In concentrations, and the doping level in the well. Schrdinger and Poisson equations are solved self-consistently by taking the free and bound surface charge concentrations into account. Many-body effects, namely, depolarization and excitonic shifts are also included in the calculations. Results for transition energies, oscillator strength, and the absorption lineshape up to nonlinear regime are represented as functions of the parameters mentioned. The well width (total and constituent layers separately) and In concentration dependence of the built-in electric field are exploited to tune the intersubband transition energies.

Y?ld?r?m, Hasan, E-mail: hasanyildirim@karabuk.edu.tr [Department of Occupational Health and Safety, School of Health, Karabuk University, Karabuk 78050 (Turkey); Aslan, Bulent, E-mail: bulentaslan@anadolu.edu.tr [Department of Physics, Faculty of Science, Anadolu University Yunus Emre Campus, Eskisehir 26470 (Turkey)

2014-04-28T23:59:59.000Z

374

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

SciTech Connect (OSTI)

We discuss recent developments in III-V multijunction solar cells, focusing on adding a fourth junction to the Ga0.5In0.5P/GaAs/Ga0.75In0.25As inverted three-junction cell. This cell, grown inverted on GaAs so that the lattice-mismatched Ga0.75In0.25As 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 GaxIn1-xAs 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 GaxIn1-xAs 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.

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

2006-05-01T23:59:59.000Z

375

Effective masses for small nitrogen concentrations in InGaAsN alloys on GaAs  

SciTech Connect (OSTI)

The variation of the value of the linewidth of an excitonic transition in InGaAsN alloys (1% and 2% nitrogen) as a function of hydrostatic pressure using photoluminescence spectroscopy is studied at 4K. The excitonic linewidth increases as a function of pressure until about 100 kbar after which it tends to saturate. This pressure dependent excitonic linewidth is used to derive the pressure variation of the exciton reduced mass using a theoretical formalism based on the premise that the broadening of the excitonic transition is caused primarily by compositional fluctuations in a completely disordered alloy. The linewidth derived ambient pressure masses are compared and found to be in agreement with other mass measurements. The variation of this derived mass is compared with the results from a nearly first-principles approach in which calculations based on the local density approximation to the Kohn-Sham density functional theory are corrected using a small amount of experimental input.

JONES,ERIC D.; ALLERMAN,ANDREW A.; KURTZ,STEVEN R.; FRITZ,IAN J.; MODINE,NORMAND A.; SIEG,ROBERT M.; BAJAJ,K.K.; TOZER,S.W.; WEI,X.

2000-05-11T23:59:59.000Z

376

Photoluminescence from InGaAs/GaAs quantum well regrown on a buried patterned oxidized AlAs layer  

SciTech Connect (OSTI)

We present a quasi-planar technological approach for forming a flexible and versatile confinement scheme based on oxidation of AlGaAs buried layers combined to an epitaxial regrowth. This method improves the electrical and optical confinements compared to the lateral oxidation since it allows to define confinement areas from a planar surface. This technique is suitable for the realization of advanced integrated photonic components arrays with close device-to-device spacing such as two-dimensional arrays of vertical-cavity surface-emitting lasers. Our results prove that the oxidation and epitaxial regrowth can be sequenced in a process flow, leading to viable confinement while preserving good radiative properties.

Chouchane, F.; Makhloufi, H.; Calvez, S.; Fontaine, C.; Almuneau, G., E-mail: almuneau@laas.fr [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse (France); Universit de Toulouse, UPS, F-31400 Toulouse (France)

2014-02-10T23:59:59.000Z

377

Integration of inverted InGaAs MSM array on Si substrate through low temperature  

E-Print Network [OSTI]

to reduce thermal stress at the interface. Huang et al. [2] presented a thin-film InGaAs MSM PD bonded to Si layers including those on InGaAs MSMs and Si/SiO2 is 860 nm. eching window InP epi-layer SiO2 Si Ti Au Au HCl:H3PO4 (1:1) to open a photodetection window. Citric acid was used to remove the InGaAs etching

Huang, Zhaoran "Rena"

378

Design and Experimental Characterization of an Erbium Doped GaN Waveguide  

E-Print Network [OSTI]

temperatures as compared to other semiconductor host materials such as Si and GaAs. 1540nm optical emission in Er- doped waveguide has also been demonstrated using a 365nm light emitting diode as the optical pumping source. UV pumping above the GaN bandgap....9 eV In Table 2 - 1, GaN is the semiconductor material with the largest bandgap (SiO2 is not a semiconductor), which has proven to be an accomplished host of erbium, with reports of fabrication of light- emitting diodes operating in the visible...

Wang, Qian

2012-05-31T23:59:59.000Z

379

Low Cost Production of InGaN for Next-Generation Photovoltaic Devices  

SciTech Connect (OSTI)

The goal of this project is to develop a low-cost and low-energy technology for production of photovoltaic devices based on InGaN materials. This project builds on the ongoing development by Structured Materials Industries (SMI), of novel thin film deposition technology for Group III-Nitride materials, which is capable of depositing Group-III nitride materials at significantly lower costs and significantly lower energy usage compared to conventional deposition techniques. During this project, SMI demonstrated deposition of GaN and InGaN films using metalorganic sources, and demonstrated compatibility of the process with standard substrate materials and hardware components.

Nick M. Sbrockey, Shangzhu Sun, Gary S. Tompa,

2012-07-09T23:59:59.000Z

380

Nano-porosity in GaSb induced by swift heavy ion irradiation  

SciTech Connect (OSTI)

Nano-porous structures form in GaSb after ion irradiation with 185 MeV Au ions. The porous layer formation is governed by the dominant electronic energy loss at this energy regime. The porous layer morphology differs significantly from that previously reported for low-energy, ion-irradiated GaSb. Prior to the onset of porosity, positron annihilation lifetime spectroscopy indicates the formation of small vacancy clusters in single ion impacts, while transmission electron microscopy reveals fragmentation of the GaSb into nanocrystallites embedded in an amorphous matrix. Following this fragmentation process, macroscopic porosity forms, presumably within the amorphous phase.

Kluth, P., E-mail: patrick.kluth@anu.edu.au; Schnohr, C. S.; Giulian, R.; Araujo, L. L.; Lei, W.; Rodriguez, M. D.; Afra, B.; Bierschenk, T.; Ridgway, M. C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Sullivan, J.; Weed, R. [ARC Centre for Antimatter-Matter Studies, AMPL, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Li, W.; Ewing, R. C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005 (United States)

2014-01-13T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Journal of Crystal Growth 293 (2006) 273277 A study of semi-insulating GaN grown on AlN buffer/sapphire  

E-Print Network [OSTI]

-temperature GaN interlayer. In comparison with the normal GaN grown on sapphire, the crystal quality measurement results of GaN grown directly on an AlN buffer indicated that the as-grown-undoped Ga, or high density of edge-type dislocations [6­10]. However, Fe and other heavy metals tend to have reactor

Ozbay, Ekmel

382

ERIC M. WARBURG CHAPTERS Atlanta Boca Raton Boston  

E-Print Network [OSTI]

development. With a strong background in institutional analysis and capacity building in sustainable standards for "green" investments and ethics of sustainability on the corporate and governmental levels. Andreas. Kraemer serves on the Boards of the Bellagio Forum for Sustainable Development and the French

Sheridan, Jennifer

383

Clark Atlanta Universities (CAU) Energy Related Research Capabilities...  

Office of Environmental Management (EM)

Outlook Conference Ronald Reagan Building and International Trade Center HYDROGEN AND FUEL CELL EDUCATION AT CALIFORNIA STATE UNIVERSITY, LOS ANGELES GATE Center for Automotive...

384

Energy Management Program at Atlanta Postal Service Distribution Center  

E-Print Network [OSTI]

The US Postal Service operates more than 38,000 post offices across the country and spends $350 million annually on utilities (1). Driven by President Clinton's 1999 Executive Order that mandates a 35 percent reduction in federal energy consumption...

Brown, M.; Ansari, A.

2001-01-01T23:59:59.000Z

385

atlanta metropolitan area: Topics by E-print Network  

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

all-to-all traffic and regular ... Guan, Kyle C. 10 Impact of primary formaldehyde on air pollution in the Mexico City Metropolitan Area MIT - DSpace Summary: Formaldehyde (HCHO)...

386

From the Atlanta Workshop -Use Satellite Data for Model Evaluation  

E-Print Network [OSTI]

Assimilation dries surface Control - Model too cool due to moisture Plan to revisit August 2006 Texas evaluations 1. Clouds Clouds play a major role in photolysis rates , temperature and wet chemistry. Models temperature #12;model (control) vs. satellite retrieval Satellite retrievals (K) model (sat. assim.) vs

Jacob, Daniel J.

387

North Atlanta, Georgia: Energy Resources | 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 on Google Bookmark EERE: Alternative Fuels Data CenterFranconia, Virginia: Energy ResourcesLoading map...(Utility Company) Jump to:City)Norristown, Pennsylvania: EnergyCoatingArlington

388

City of Atlanta Video (Text Version) | Department of Energy  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:YearRound-Up fromDepartmentTieCelebrate Earth DayFuels ChemicalChrisCincinnatinear Paducah

389

Better Buildings Challenge, Atlanta Nears Halfway Mark in Meeting Citywide  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE: Alternative FuelsBSCmemo.pdf BSCmemo.pdf BSCmemo.pdf MoreEnergyNaturalDepartmentFeet |Goal of

390

Workplace Charging Challenge Partner: City of Atlanta | Department of  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartment ofDepartment of Energyof EnergyEnergy Cisco Systems, Inc. Cisco

391

WNRC diverting to Atlanta FRC | Department of Energy  

Office of Environmental Management (EM)

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGYWomen Owned SmallOf The 2012NuclearBradley Nickell DirectorEnergyDepartmentWNRC

392

New American Home(R): Atlanta, Georgia--2002  

SciTech Connect (OSTI)

The New American Home is an annual showcase project designed by committee and co-sponsored by the National Association of Home Builders' (NAHB) National Council of the Housing Industry (NCHI). This year's project is built by John Wieland Homes and Neighborhoods and supported by IBACOS.

Not Available

2002-01-01T23:59:59.000Z

393

Making Connections for Atlanta Students | Department of Energy  

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

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 on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankCombustion | Department of Energy Low-TemperatureEnergy Maine State Historic5The CurrentMaking

394

Y-12, early records from the National Archives at Atlanta  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear SecurityTensile Strain Switched FerromagnetismWaste andAnniversary, part 2 Continuing the 70 thbegins Asearly records

395

Microsoft Word - Final TEC Notes Atlanta 07.doc  

Office of Environmental Management (EM)

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergyENERGY TAXBalanced Scorecard Federal Compliance Review David Sandalow Assistant Secretary of

396

Alternative Fuels Data Center: Atlanta Airport Converts Shuttles to CNG  

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth (AOD)ProductssondeadjustsondeadjustAbout theOFFICE OF RESEARCHThermalPlug-inTexas

397

Atlanta Community Leaders' Institute Conference | 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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarly Career Scientists' ResearchTheMarketing, Inc. | DepartmentDr. David Satcher speaks at the Community

398

Atlanta TEC Meeting -- Tribal Group Summary 3-6-07  

Office of Environmental Management (EM)

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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "of EnergyEnergy Cooperation |South42.2 (April 2012)Tie Ltd |Line,Conference on InnovativeEfficiency

399

GaInAsSb/A1GaAsSb/Sb Thermophotovoltaic Devices With an Internal Back-Surface Reflector Formed by Wafer Bonding  

SciTech Connect (OSTI)

A novel implementation for GAInAsSb/AlGaAsSb/GaSb TPV cells with an internal back-surface reflector (BSR) formed by wafer bonding to GaAs is demonstrated. The SiO{sub x}/Ti/Au internal BSR enhances optical absorption within the device, while the dielectric layer provides electrical isolation. This configuration has the potential to improve TPV device performance; is compatible with monolithic series-interconnection of TPV cells for building voltage; and can mitigate the requirements of filters used for front-surface spectral control. At a short-circuit density of 0.4 A/cm{sup 2}, the open-circuit voltage of a single TPV cell is 0.2 V, compared to 0.37 and 1.8 V for 2- and 10-junction series-interconnected TPV cells, respectively.

C.A. Wang; R.K. Huang; D.A. Shiau; M.K. Connors; P.G. Murphy; P.W. O'brien; A.C. Anderson; D.M. DePoy; G. Nichols; M.N. Palmasiano

2002-12-18T23:59:59.000Z

400

Highly tunable quantum Hall far-infrared photodetector by use of GaAs/Al{sub x}Ga{sub 1?x}As-graphene composite material  

SciTech Connect (OSTI)

We have developed a highly tunable, narrow band far-infrared (FIR) photodetector which utilizes the characteristic merits of graphene and two-dimensional electron gas (2DEG) in GaAs/Al{sub x}Ga{sub 1?x}As heterostructure in the Quantum Hall states (QHS). The heterostructure surface is covered with chemical vapor-deposited graphene, which functions as a transparent top-gate to vary the electron density of the 2DEG. FIR response observed in the vicinity of integer QH regime can be effectively tuned in a wide range of 27102?cm{sup ?1} with a bias voltage less than ?1?V. In addition, we have found that the presence of graphene can genuinely modulate the photoresponse. Our results demonstrate a promising direction for realizing a tunable long-wavelength FIR detector using QHS in GaAs 2DEG/ graphene composite material.

Tang, Chiu-Chun [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Ling, D. C. [Department of Physics, Tamkang University, Tamsui Dist., New Taipei City 25137, Taiwan (China); Chi, C. C.; Chen, Jeng-Chung [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

2014-11-03T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Bias dependence and correlation of the cathodoluminescence and electron beam induced current from an InGaN/GaN light emitting diode  

SciTech Connect (OSTI)

Micron-scale mapping has been employed to study a contacted InGaN/GaN LED using combined electroluminescence (EL), cathodoluminescence (CL), and electron beam induced current (EBIC). Correlations between parameters, such as the EBIC and CL intensity, were studied as a function of applied bias. The CL and EBIC maps reveal small areas, 210??m in size, which have increased nonradiative recombination rate and/or a lower conductivity. The CL emission from these spots is blue shifted, by 3040?meV. Increasing the reverse bias causes the size of the spots to decrease, due to competition between in-plane diffusion and drift in the growth direction. EL mapping shows large bright areas (?100??m) which also have increased EBIC, indicating domains of increased conductivity in the p and/or n-GaN.

Wallace, M. J.; Edwards, P. R.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Kappers, M. J.; Oehler, F.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Hopkins, M. A.; Sivaraya, S.; Allsopp, D. W. E. [Department of Electronic and Electrical Engineering, University of Bath, Bath BA2 7AY (United Kingdom)

2014-07-21T23:59:59.000Z

402

Mid-infrared electro-luminescence and absorption from AlGaN/GaN-based multi-quantum well inter-subband structures  

SciTech Connect (OSTI)

We present electro-modulated absorption and electro-luminescence measurements on chirped AlGaN/GaN-based multi-quantum well inter-subband structures grown by metal-organic vapour phase epitaxy. The absorption signal is a TM-polarized, 70?meV wide feature centred at 230?meV. At medium injection current, a 58?meV wide luminescence peak corresponding to an inter-subband transition at 1450?cm{sup ?1} (180?meV) is observed. Under high injection current, we measured a 4?meV wide structure peaking at 92.5?meV in the luminescence spectrum. The energy location of this peak is exactly at the longitudinal optical phonon of GaN.

Hofstetter, Daniel, E-mail: Daniel.Hofstetter@unine.ch [University of Neuchtel, Institute of Physics, 51 Avenue de Bellevaux, Neuchtel, CH2009 (Switzerland); Bour, David P. [Avogy, Inc., 677 River Oaks Parkway, San Jose, California 95134 (United States); Kirste, Lutz [Fraunhofer Institute for Applied Solid State Physics (IAF), Tullastrasse 72, D-79108 Freiburg i. Brsg. (Germany)

2014-06-16T23:59:59.000Z

403

OMVPE Growth of Quaternary (Al,Ga,In)N for UV Optoelectronics (title change from A)  

SciTech Connect (OSTI)

We report the growth and characterization of quaternary AlGaInN. A combination of photoluminescence (PL), high-resolution x-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) characterizations enables us to explore the contours of constant PL peak energy and lattice parameter as functions of the quaternary compositions. The observation of room temperature PL emission at 351nm (with 20% Al and 5% In) renders initial evidence that the quaternary could be used to provide confinement for GaInN (and possibly GaN). AlGaInN/GrdnN MQW heterostructures have been grown; both XRD and PL measurements suggest the possibility of incorporating this quaternary into optoelectronic devices.

HAN,JUNG; FIGIEL,JEFFREY J.; PETERSEN,GARY A.; MYERS JR.,SAMUEL M.; CRAWFORD,MARY H.; BANAS,MICHAEL ANTHONY; HEARNE,SEAN JOSEPH

2000-01-18T23:59:59.000Z

404

Thermal annealing characteristics of Si and Mg-implanted GaN thin films  

SciTech Connect (OSTI)

In this letter, we report the results of ion implantation of GaN using {sup 28}Si and {sup 24}Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 40 keV 10{sup 14} cm{sup {minus}2} Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690{degree}C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties. {copyright} {ital 1996 American Institute of Physics.}

Chan, J.S.; Cheung, N.W. [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)] [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States); Schloss, L.; Jones, E.; Wong, W.S.; Newman, N.; Liu, X.; Weber, E.R. [Department of Material Science and Mineral Engineering, University of California, Berkeley, California 64720 (United States)] [Department of Material Science and Mineral Engineering, University of California, Berkeley, California 64720 (United States); Gassman, A.; Rubin, M.D. [Lawrence Berkeley Laboratory, 1 Cyclotron Road, University of California, Berkeley, California 64720 (United States)] [Lawrence Berkeley Laboratory, 1 Cyclotron Road, University of California, Berkeley, California 64720 (United States)

1996-05-01T23:59:59.000Z

405

In-situ ellipsometry: Identification of surface terminations during GaN growth , T. Schmidtling1  

E-Print Network [OSTI]

1 In-situ ellipsometry: Identification of surface terminations during GaN growth C. Cobet1 , T SE, one is not limited to any special bulk or surface symmetry for optical characterisation. In PAMBE

Feenstra, Randall

406

Unambiguous determination of carrier concentration and mobility for InAs/GaSb superlattice photodiode optimization  

SciTech Connect (OSTI)

In this communication we report on electrical properties of nonintentionally doped (nid) type II InAs/GaSb superlattice grown by molecular beam epitaxy. We present a simple technological process which, thanks to the suppression of substrate, allows direct Hall measurement on superlattice structures grown on conductive GaSb substrate. Two samples were used to characterize the transport: one grown on a semi-insulating GaAs substrate and another grown on n-GaSb substrate where a etch stop layer was inserted to remove the conductive substrate. Mobilities and carrier concentrations have been measured as a function of temperature (77-300 K), and compared with capacitance-voltage characteristic at 80 K of a photodiode comprising a similar nid superlattice.

Cervera, C.; Rodriguez, J. B.; Perez, J. P.; Aiet-Kaci, H.; Chaghi, R.; Christol, P. [Institut d'Electronique du Sud (IES), UMR CNRS 5214, Case 067, Universite Montpellier 2, 34095 Montpellier Cedex 05 (France); Konczewicz, L.; Contreras, S. [Groupe d'Etude des Semiconducteurs (GES), UMR CNRS 5650, Case 074, Universite Montpellier 2, 34095 Montpellier Cedex 5 (France)

2009-08-01T23:59:59.000Z

407

Ambipolar spin diffusion and D'yakonov-Perel' spin relaxation in GaAs quantum wells  

E-Print Network [OSTI]

We report theoretical and experimental studies of ambipolar spin diffusion in a semiconductor. A circularly polarized laser pulse is used to excite spin-polarized carriers in a GaAs multiple quantum-well sample at 80 K. ...

Zhao, Hui; Mower, Matt; Vignale, G.

2009-03-01T23:59:59.000Z

408

GaN quantum dot superlattices grown by molecular beam epitaxy at high temperature  

E-Print Network [OSTI]

P-based optoelectronic devices with Si microelectronic devices. This method uses a Au-Ge eutectic alloy as the bonding. The realization of integrafion of GaAs- and InP-based optoelectronic devices with Si microelectronic components

409

Physics of electrical degradation in GaN high electron mobility transistors  

E-Print Network [OSTI]

The deployment of GaN high electron mobility transistors (HEMT) in RF power applications is currently bottlenecked by their limited reliability. Obtaining the required reliability is a difficult issue due to the high voltage ...

Joh, Jungwoo

2009-01-01T23:59:59.000Z

410

Simulation and fabrication of GaN-based vertical and lateral normally-off power transistors  

E-Print Network [OSTI]

This thesis is divided in two parts. First, self-consistent electro-thermal simulations have been performed for single finger and multi-finger GaN-based vertical and lateral power transistors and were validated with ...

Zhang, Yuhao, S.M. Massachusetts Institute of Technology

2013-01-01T23:59:59.000Z

411

E-Print Network 3.0 - agents ga gb Sample Search Results  

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

Advanced Search Sample search results for: agents ga gb Page: << < 1 2 3 4 5 > >> 1 Philosophy 148 --Assignment 3 This assignment is due Thursday, April 3. If you work in a...

412

Computational Thermodynamics of CoNiGa High Temperature Shape Memory Alloys  

E-Print Network [OSTI]

Shape Memory Alloys (SMAs) are advanced materials with interesting properties such as pseudoelasticity (PE) and the shape memory effect (SME). Recently, the CoNiGa system has emerged as the basis for very promising High Temperature Shape Memory...

Chari, Arpita

2012-10-19T23:59:59.000Z

413

Recombination Lifetime of InxGa1-xAs Alloys Used in Thermophotovoltaic Converters  

SciTech Connect (OSTI)

The family of ternary compounds of composition InxGa1-xAs are of considerable interest for thermophotovoltaic energy converters. The recombination lifetimes of the various compositions are critical to the successful application of these materials as efficient converters. Here we will describe experimental results on the composition. In0.53Ga0.47 that is lattice-matched to InP. We will also describe lifetime results on the compositions In0.68Ga0.32As, with bandgap of 0.60 eV to compositions In0.78Ga0.22As with a bandgap of 0.50 eV. Double heterostructure confinement devices have been made over a range of both n- and p-type doping. These results are preliminary, but the goal is to obtain the radiative and Auger recombination coefficients for the alloys in this composition range.

Ahrenkiel, R. K.; Ellingson, R.; Johnston, S.; Webb, J.; Carapella, J.; Wanlass, M.

1999-02-16T23:59:59.000Z

414

Frequency Response of Acoustic-Assisted NiMnGa Ferromagnetic- Shape-Memory-Alloy Actuator  

E-Print Network [OSTI]

A prototype of NiMnGa based ferromagnetic-shape-memory-alloy (FSMA) actuator was designed and built; an acoustic-assist technique was applied to the actuator to enhance its performance. A piezoelectric stack actuator was ...

Techapiesancharoenkij, Ratchatee

415

Understanding and development of combined acoustic and magnetic actuation of Ni?MnGa single crystals  

E-Print Network [OSTI]

Ni-Mn-Ga based ferromagnetic shape memory alloys (FSMAs) have emerged as a promising new class of active materials capable of producing a large (several %) magnetic-field-induced strain (MFIS). FSMAs still have several ...

Techapiesancharoenkij, Ratchatee, 1979-

2007-01-01T23:59:59.000Z

416

Ferromagnetism and the electronic band structure in (Ga,Mn)(Bi,As) epitaxial layers  

SciTech Connect (OSTI)

Impact of Bi incorporation into (Ga,Mn)As layers on their electronic- and band-structures as well as their magnetic and structural properties has been studied. Homogenous (Ga,Mn)(Bi,As) layers of high structural perfection have been grown by the low-temperature molecular-beam epitaxy technique. Post-growth annealing treatment of the layers results in an improvement of their structural and magnetic properties and an increase in the hole concentration in the layers. The modulation photoreflectance spectroscopy results are consistent with the valence-band model of hole-mediated ferromagnetism in the layers. This material combines the properties of (Ga,Mn)As and Ga(Bi,As) ternary compounds and offers the possibility of tuning its electrical and magnetic properties by controlling the alloy composition.

Yastrubchak, O., E-mail: yastrub@hektor.umcs.lublin.pl [Institute of Physics, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Sk?odowskiej 1, 20-031 Lublin (Poland); Institute of Semiconductor Physics, National Academy of Sciences, 41 pr. Nauki, 03028 Kyiv (Ukraine); Sadowski, J. [MAX-IV Laboratory, Lund University, P.O. Box 118, SE-221 00 Lund (Sweden); Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Gluba, L.; ?uk, J.; Kulik, M. [Institute of Physics, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Sk?odowskiej 1, 20-031 Lublin (Poland); Domagala, J. Z.; Andrearczyk, T.; Wosinski, T. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Rawski, M. [Analytical Laboratory, Maria Curie-Sklodowska University in Lublin, Pl. M. Curie-Sk?odowskiej 3, 20-031 Lublin (Poland)

2014-08-18T23:59:59.000Z

417

Strain analysis of compositionally tailored interfaces in InAs/GaSb superlattices  

SciTech Connect (OSTI)

The effect of interface composition control on interfacial strain distribution in InAs/GaSb superlattices on (100)-GaSb substrates is investigated by atomic resolution scanning transmission electron microscopy. The interface composition was controlled by either depositing InSb at each interface or soaking the GaSb-on-InAs interface under Sb{sub 2} atmosphere. The strain profiles reveal a distinct difference in the extent to which the superlattice strain is balanced using the two methods. In particular, they indicate that the degree of strain balance achievable with soaking is inherently limited by the arsenic surface coverage during GaSb-on-InAs interface formation, emphasizing the influence of V/III flux ratio at this interface. The results also explain observed X-ray diffraction profiles.

Mahalingam, Krishnamurthy; Haugan, Heather J.; Brown, Gail J.; Aronow, Andrew J. [AFRL/RXAN, Materials and Manufacturing Directorate Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433-7707 (United States)] [AFRL/RXAN, Materials and Manufacturing Directorate Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433-7707 (United States)

2013-11-18T23:59:59.000Z

418

Prospects for high temperature ferromagnetism in (Ga,Mn)As semiconductors  

E-Print Network [OSTI]

-quality metallic samples increases linearly with the number of uncompensated local moments on Mn-Ga acceptors, with no sign of saturation. Room temperature ferromagnetism is expected for a 10% concentration of these local moments. Our magnetotransport...

Jungwirth, T.; Wang, KY; Masek, J.; Edmonds, KW; Konig, J.; Sinova, Jairo; Polini, M.; Goncharuk, NA; MacDonald, AH; Sawicki, M.; Rushforth, AW; Campion, RP; Zhao, LX; Foxon, CT; Gallagher, BL.

2005-01-01T23:59:59.000Z

419

Watching GaN Nanowires Grow Eric A. Stach,*, Peter J. Pauzauskie, Tevye Kuykendall,  

E-Print Network [OSTI]

Vision, Lawrence Berkeley National Laboratory, Berkeley, California 94720, and Department of Chemistry, Uni and experimentally demonstrated that congruent sublimation of GaN is possible, which yields diatomic or polymeric

Yang, Peidong

420

MOCVD growth of In GaP-based heterostructures for light emitting devices  

E-Print Network [OSTI]

In this work, we examine fundamental materials processes in the growth of indium gallium phosphide (InGaP) via metalorganic chemical vapor deposition (MOCVD). In particular, we realize improvements in the epitaxial integration ...

McGill, Lisa Megan, 1975-

2004-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
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421

Local stress-induced effects on AlGaAs/AlOx oxidation front shape  

SciTech Connect (OSTI)

The lateral oxidation of thick AlGaAs layers (>500?nm) is studied. An uncommon shape of the oxide tip is evidenced and attributed to the embedded stress distribution, inherent to the oxidation reaction. Experimental and numerical studies of the internal strain in oxidized Al{sub x}Ga{sub 1?x}As/GaAs structures were carried out by dark-field electron holography and finite element methods. A mapping of the strain distribution around the AlGaAs/oxide interface demonstrates the main role of internal stress on the shaping of the oxide front. These results demonstrate the high relevance of strain in oxide-confined III-V devices, in particular, with over-500-nm thick AlOx confinement layers.

Chouchane, F.; Almuneau, G., E-mail: almuneau@laas.fr; Arnoult, A.; Lacoste, G.; Fontaine, C. [CNRS, LAAS, 7 avenue du colonel Roche, F-31400 Toulouse (France); Univ de Toulouse, UPS, LAAS, F-31400 Toulouse (France); Cherkashin, N. [Univ de Toulouse, UPS, LAAS, F-31400 Toulouse (France); CNRS, CEMES, 29 Rue Jeanne Marvig, 31055 Toulouse Cedex 4 (France)

2014-07-28T23:59:59.000Z

422

Deeply-scaled GaN high electron mobility transistors for RF applications  

E-Print Network [OSTI]

Due to the unique combination of large critical breakdown field and high electron velocity, GaN-based high electron mobility transistors (HEMTs) have great potential for next generation high power RF amplifiers. The ...

Lee, Dong Seup

2014-01-01T23:59:59.000Z

423

Impact of stress relaxation in GaAsSb cladding layers on quantum dot creation in InAs/GaAsSb structures grown on GaAs (001)  

SciTech Connect (OSTI)

We describe InAs quantum dot creation in InAs/GaAsSb barrier structures grown on GaAs (001) wafers by molecular beam epitaxy. The structures consist of 20-nm-thick GaAsSb barrier layers with Sb content of 8%, 13%, 15%, 16%, and 37% enclosing 2 monolayers of self-assembled InAs quantum dots. Transmission electron microscopy and X-ray diffraction results indicate the onset of relaxation of the GaAsSb layers at around 15% Sb content with intersected 60 dislocation semi-loops, and edge segments created within the volume of the epitaxial structures. 38% relaxation of initial elastic stress is seen for 37% Sb content, accompanied by the creation of a dense net of dislocations. The degradation of In surface migration by these dislocation trenches is so severe that quantum dot formation is completely suppressed. The results highlight the importance of understanding defect formation during stress relaxation for quantum dot structures particularly those with larger numbers of InAs quantum-dot layers, such as those proposed for realizing an intermediate band material.

Bremner, S. P. [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney 2052 (Australia)] [School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney 2052 (Australia); Ban, K.-Y.; Faleev, N. N.; Honsberg, C. B. [School of Electrical, Computer and Energy Engineering, Ira A. Fulton Schools of Engineering, Solar Power Lab, Arizona State University, Tempe, Arizona 85287 (United States)] [School of Electrical, Computer and Energy Engineering, Ira A. Fulton Schools of Engineering, Solar Power Lab, Arizona State University, Tempe, Arizona 85287 (United States); Smith, D. J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)] [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

2013-09-14T23:59:59.000Z

424

Effect of MnAs/GaAs(001) film accommodations on the phase-transition temperature  

SciTech Connect (OSTI)

The phase-transition temperature of MnAs epitaxial films grown by molecular-beam epitaxy on GaAs(001) with different crystalline accommodations was studied by specular and grazing incidence x-ray diffraction. The transition temperature of MnAs films with tilted hexagonal c-axis orientations with respect to the GaAs substrate is higher than the most investigated nontilted films and reaches a value above room temperature, which is more suitable for device applications.

Iikawa, F.; Brasil, M.J.S.P.; Couto, O.D.D.; Adriano, C.; Giles, C.; Daeweritz, L. [Instituto de Fisica 'Gleb Wataghin', UNICAMP, Campinas-SP, C.P. 6165, 13083-970 (Brazil); Instituto de Fisica 'Gleb Wataghin', UNICAMP, Campinas-SP, C.P. 6165, 13083-970, Brazil and Laboratorio Nacional de Luz Sincrotron, CP-6192, 13084-971 Campinas-SP (Brazil); Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

2004-09-20T23:59:59.000Z

425

Electron transfer and capture dynamics in ZnSe quantum wells grown on GaAs  

SciTech Connect (OSTI)

We investigate the transfer and capture dynamics of electrons in phase coherent photorefractive ZnSe quantum wells grown on GaAs using degenerate three-beam four-wave-mixing. The measurements reveal electron capture times by the quantum well in the order of several tens of picoseconds and a transit time of approximately 5 picoseconds from the GaAs substrate through the ZnMgSe barrier.

Dongol, A.; Wagner, H. P. [Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States)

2013-12-04T23:59:59.000Z

426

Combustion of Nano-Aluminum and Liquid Water G.A. Risha, S.F. Son  

E-Print Network [OSTI]

1 Combustion of Nano-Aluminum and Liquid Water G.A. Risha, S.F. Son , R.A. Yetter, V. Yang, and B: Supplemental materials submitted #12;2 Combustion of Nano-Aluminum and Liquid Water G.A. Risha, S.F. Son, R of nano-aluminum (nAl) and liquid water has been conducted. In particular, linear and mass-burning rates

Yang, Vigor

427

Tunnel optical radiation in In{sub x}Ga{sub 1?x}N  

SciTech Connect (OSTI)

An investigation of tunnel optical radiation in epitaxial layers of n-type In{sub x}Ga{sub 1?x}N grown on p-type GaN by novel plasma based migration enhanced epitaxy is presented. Experimental results of electro-luminescence spectra for In{sub x}Ga{sub 1?x}N/p?GaN hetero-junctions were obtained and they show two well expressed optical bands - one in range 500-540 nm and other in range 550-610 nm. An interesting detail is that each band begins and ends by sharp drops of the radiation, which nearly approach zero. A theoretical investigation of the unusual behavior of these spectra was done using LCAO electron band structure calculations. The optical ranges of these bands show that the radiation occurs in the In{sub x}Ga{sub 1?x}N region. In fact, substitutions of In atoms in Ga sites creates defects in the structure of In{sub x}Ga{sub 1?x}N and the corresponding LCAO matrix elements are found on this basis. The LCAO electron band structures are calculated considering the interactions between nearest-neighbor orbitals. Electron energy pockets are found in both the conduction and the valence bands at the ? point of the electron band structures. Also it is found that these pockets are separated by distances, for which there is overlapping between the electron wave functions describing localized states belonging to the pockets, and as a result tunnel optical radiation can take place. This type of electron transition - between such a pocket in the conduction band and a pocket in the valence band - occurs in In{sub x}Ga{sub 1?x}N, causing the above described optical bands. This conclusion concurs with the fact that the shapes of these bands change with change of the applied voltage.

Alexandrov, Dimiter; Skerget, Shawn [Semiconductor Research Laboratory, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario P7B5E1 (Canada)

2014-02-21T23:59:59.000Z

428

Scattering due to Schottky barrier height spatial fluctuation on two dimensional electron gas in AlGaN/GaN high electron mobility transistors  

SciTech Connect (OSTI)

A scattering mechanism related to the Schottky barrier height (SBH) spatial fluctuation of the two dimensional electron gas (2DEG) in AlGaN/GaN heterostructures is presented. We find that the low field mobility is on the order of 10{sup 4}10{sup 6} cm{sup 2}/Vs. The 2DEG transport properties are found to be influenced by both the mobility and 2DEG density variations caused by the SBH fluctuation. Our results indicate that a uniform Schottky contact is highly desired to minimize the influence of SBH inhomogeneity on the device performance.

Li, Huijie; Liu, Guipeng, E-mail: liugp@semi.ac.cn; Wei, Hongyuan; Jiao, Chunmei; Wang, Jianxia; Zhang, Heng; Dong Jin, Dong; Feng, Yuxia; Yang, Shaoyan, E-mail: sh-yyang@semi.ac.cn; Wang, Lianshan; Zhu, Qinsheng; Wang, Zhan-Guo [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, People's Republic of China and Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)] [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, People's Republic of China and Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

2013-12-02T23:59:59.000Z

429

Anisotropic scattering effect of the inclined misfit dislocation on the two-dimensional electron gas in Al(In)GaN/GaN heterostructures  

SciTech Connect (OSTI)

In this paper, a theory is developed to study the anisotropic scattering effect of the inclined misfit dislocation on the two-dimensional electron gas in Al(In)GaN/GaN heterostructures. The inclined misfit dislocation, which differs from the well-known vertical threading dislocation, has a remarkable tilt angle from the vertical. The predicted electron mobility shows a remarkable anisotropy. It has a maximum mobility value along the direction perpendicular to the projection of the inclined dislocation line, and a minimum mobility value along the direction parallel to the projection. The degree of the anisotropic scattering effect will be even greater with the increase of the tilt angle.

Jin, Dong-Dong [Key Laboratory of Semiconductor Materials Science, and Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Department of Physics, Tsinghua University, Beijing 100084 (China); Wang, Lian-shan, E-mail: ls-wang@semi.ac.cn; Yang, Shao-Yan, E-mail: sh-yyang@semi.ac.cn; Li, Hui-jie; Zhang, Heng; Wang, Jian-xia; Xiang, Ruo-fei; Wei, Hong-yuan; Jiao, Chun-mei; Liu, Xiang-Lin; Zhu, Qin-Sheng, E-mail: qszhu@semi.ac.cn; Wang, Zhan-Guo [Key Laboratory of Semiconductor Materials Science, and Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhang, Liu-Wan [Department of Physics, Tsinghua University, Beijing 100084 (China)

2014-01-28T23:59:59.000Z

430

Study of the growth mechanisms of GaN/(Al, Ga)N quantum dots: Correlation between structural and optical properties  

SciTech Connect (OSTI)

The ammonia-based molecular beam epitaxy of GaN/(Al, Ga)N quantum dots is investigated using reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy and photoluminescence. The main steps of the formation kinetics are identified and the influence of diffusion and evaporation processes on both the quantum dot and the wetting layer morphology is addressed. The correlation between the optical and structural properties of such structures finally allows for the analysis of matter exchanges between the quantum dots and the wetting layer during capping.

Sergent, S. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Universite de Nice Sophia Antipolis, Parc Valrose, F-06102 Nice Cedex 2 (France); Damilano, B.; Huault, T.; Brault, J.; Tottereau, O.; Vennegues, P.; Leroux, M.; Semond, F.; Massies, J. [CRHEA-CNRS, Rue Bernard Gregory, Sophia Antipolis, 06560 Valbonne (France); Korytov, M.

2011-03-01T23:59:59.000Z

431

Heteroepitaxial growth and surface structure of L1{sub 0}-MnGa(111) ultra-thin films on GaN(0001)  

SciTech Connect (OSTI)

L1{sub 0}-structured MnGa(111) ultra-thin films were heteroepitaxially grown on GaN(0001) under lightly Mn-rich conditions using molecular beam epitaxy. Room-temperature scanning tunneling microscopy (STM) investigations reveal smooth terraces and angular step edges, with the surface structure consisting primarily of a 2 2 reconstruction along with small patches of 1 2. Theoretical calculations were carried out using density functional theory, and the simulated STM images were calculated using the Tersoff-Hamman approximation, revealing that a stoichiometric 1 2 and a Mn-rich 2 2 surface structure give the best agreement with the observed experimental images.

Mandru, Andrada-Oana; Wang, Kangkang; Cooper, Kevin; Ingram, David C.; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States)] [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Garcia Diaz, Reyes; Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States) [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autnoma de Mxico, Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Haider, Muhammad [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States) [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261 (Saudi Arabia)

2013-10-14T23:59:59.000Z

432

How much better are InGaN/GaN nanodisks than quantum wellsOscillator strength enhancement and changes in optical properties  

SciTech Connect (OSTI)

We show over 100-fold enhancement of the exciton oscillator strength as the diameter of an InGaN nanodisk in a GaN nanopillar is reduced from a few micrometers to less than 40?nm, corresponding to the quantum dot limit. The enhancement results from significant strain relaxation in nanodisks less than 100?nm in diameter. Meanwhile, the radiative decay rate is only improved by 10 folds due to strong reduction of the local density of photon states in small nanodisks. Further increase in the radiative decay rate can be achieved by engineering the local density of photon states, such as adding a dielectric coating.

Zhang, Lei; Hill, Tyler A.; Deng, Hui, E-mail: dengh@umich.edu, E-mail: peicheng@umich.edu [Department of Physics, University of Michigan, 450 Church Street, Ann Arbor, Michigan 48109 (United States); Lee, Leung-Kway; Teng, Chu-Hsiang; Ku, Pei-Cheng, E-mail: dengh@umich.edu, E-mail: peicheng@umich.edu [Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, Michigan 48109 (United States)

2014-02-03T23:59:59.000Z

433

The effects of Si-doped prelayers on the optical properties of InGaN/GaN single quantum well structures  

E-Print Network [OSTI]

as the excitation source. The PL decay time measurements were performed using a frequency tripled, mode-locked, Ti:sapphire laser as the excitation source (4.881 eV), with the signals being processed with a time- correlated single photon counting system. XRD and XRR... GaN/GaN structures. The SQW structures studied were deposited by met- alorganic vapor phase epitaxy on c-plane sapphire sub- strates (with a miscut of 0.25 0.1 ? along a) in a 6 2 Thomas Swan close-coupled showerhead reactor, using the quasi-two temperature...

Davies, M. J.; Dawson, P.; Massabuau, F. C.-P.; Oliver, R. A.; Humphreys, C. J.

2014-09-05T23:59:59.000Z

434

Gain uniformity of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions  

SciTech Connect (OSTI)

We report on the spatial uniformity of the gain M of InP/ InGaAsP/InGaAs avalanche photodiodes with separate absorption, grading, and multiplication regions (SAGM-APD's). Typically, these APD's exhibit less than 10 percent variation in the gain (for M less than or equal to 10) over the entire photosensitive area. The small nonuniformity which is observed shows a one-to-one correspondence with inhomogeneities in the epitaxial layers of the SAGM-APD structure. We also observe a reduction in the effective photosensitive diameter with increasing bias voltage.

Holden, W.S.; Campbell, J.C.; Dental, A.G.

1985-09-01T23:59:59.000Z

435

Frequency response of InP/InGaAsP/InGaAs avalanche photodiodes with separate absorption ''grading'' and multiplication regions  

SciTech Connect (OSTI)

We have measured the frequency response of InP/ InGaAsP/InGaAs photodiodes with separate absorption, ''grading,'' and multiplication regions (SAGM-APD's) for a wide range (2 less than or equal to M/sub 0/ less than or equal to 35) of dc gains. The results are explained in terms of a theoretical model which incorporates the transit time of carriers through the depletion region, the RC time constant, the accumulation of holes at the valence band discontinuity of the heterojunction interfaces, and the gainbandwidth limit.

Campbell, J.C.; Dentai, A.G.; Holden, W.S.; Qua, G.J.

1985-11-01T23:59:59.000Z

436

Photoluminescence from In0.5Ga0.5As/GaP quantum dots coupled to photonic crystal cavities  

E-Print Network [OSTI]

We demonstrate room temperature visible wavelength photoluminescence from In0.5Ga0.5As quantum dots embedded in a GaP membrane. Time-resolved above band photoluminescence measurements of quantum dot emission show a biexpontential decay with lifetimes of ~200 ps. We fabricate photonic crystal cavities which provide enhanced outcoupling of quantum dot emission, allowing the observation of narrow lines indicative of single quantum dot emission. This materials system is compatible with monolithic integration on Si, and is promising for high efficiency detection of single quantum dot emission as well as optoelectronic devices emitting at visible wavelengths.

Kelley Rivoire; Sonia Buckley; Yuncheng Song; Minjoo Larry Lee; Jelena Vuckovic

2012-01-05T23:59:59.000Z

437

Elemental diffusion during the droplet epitaxy growth of In(Ga)As/GaAs(001) quantum dots by metal-organic chemical vapor deposition  

SciTech Connect (OSTI)

Droplet epitaxy is an important method to produce epitaxial semiconductor quantum dots (QDs). Droplet epitaxy of III-V QDs comprises group III elemental droplet deposition and the droplet crystallization through the introduction of group V elements. Here, we report that, in the droplet epitaxy of InAs/GaAs(001) QDs using metal-organic chemical vapor deposition, significant elemental diffusion from the substrate to In droplets occurs, resulting in the formation of In(Ga)As crystals, before As flux is provided. The supply of As flux suppresses the further elemental diffusion from the substrate and promotes surface migration, leading to large island formation with a low island density.

Chen, Z. B.; Chen, B.; Wang, Y. B.; Liao, X. Z., E-mail: xiaozhou.liao@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Lei, W. [School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Tan, H. H.; Jagadish, C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Zou, J. [Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072 (Australia); Ringer, S. P. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia)

2014-01-13T23:59:59.000Z

438

Realizing InGaN monolithic solar-photoelectrochemical cells for artificial photosynthesis  

SciTech Connect (OSTI)

InGaN alloys are very promising for solar water splitting because they have direct bandgaps that cover almost the whole solar spectrum. The demonstration of direct solar-to-fuel conversion without external bias with the sunlight being the only energy input would pave the way for realizing photoelectrochemical (PEC) production of hydrogen by using InGaN. A monolithic solar-PEC cell based on InGaN/GaN multiple quantum wells capable to directly generate hydrogen gas under zero bias via solar water splitting is reported. Under the irradiation by a simulated sunlight (1-sun with 100 mW/cm{sup 2}), a 1.5% solar-to-fuel conversion efficiency has been achieved under zero bias, setting a fresh benchmark of employing III-nitrides for artificial photosynthesis. Time dependent hydrogen gas production photocurrent measured over a prolonged period (measured for 7 days) revealed an excellent chemical stability of InGaN in aqueous solution of hydrobromic acid. The results provide insights into the architecture design of using InGaN for artificial photosynthesis to provide usable clean fuel (hydrogen gas) with the sunlight being the only energy input.

Dahal, R.; Pantha, B. N.; 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)

2014-04-07T23:59:59.000Z

439

Correlating electroluminescence characterization and physics-based models of InGaN/GaN LEDs: Pitfalls and open issues  

SciTech Connect (OSTI)

Electroluminescence (EL) characterization of InGaN/GaN light-emitting diodes (LEDs), coupled with numerical device models of different sophistication, is routinely adopted not only to establish correlations between device efficiency and structural features, but also to make inferences about the loss mechanisms responsible for LED efficiency droop at high driving currents. The limits of this investigative approach are discussed here in a case study based on a comprehensive set of current- and temperature-dependent EL data from blue LEDs with low and high densities of threading dislocations (TDs). First, the effects limiting the applicability of simpler (closed-form and/or one-dimensional) classes of models are addressed, like lateral current crowding, vertical carrier distribution nonuniformity, and interband transition broadening. Then, the major sources of uncertainty affecting state-of-the-art numerical device simulation are reviewed and discussed, including (i) the approximations in the transport description through the multi-quantum-well active region, (ii) the alternative valence band parametrizations proposed to calculate the spontaneous emission rate, (iii) the difficulties in defining the Auger coefficients due to inadequacies in the microscopic quantum well description and the possible presence of extra, non-Auger high-current-density recombination mechanisms and/or Auger-induced leakage. In the case of the present LED structures, the application of three-dimensional numerical-simulation-based analysis to the EL data leads to an explanation of efficiency droop in terms of TD-related and Auger-like nonradiative losses, with a C coefficient in the 10{sup ?30}cm{sup 6}/s range at room temperature, close to the larger theoretical calculations reported so far. However, a study of the combined effects of structural and model uncertainties suggests that the C values thus determined could be overestimated by about an order of magnitude. This preliminary attempt at uncertainty quantification confirms, beyond the present case, the need for an improved description of carrier transport and microscopic radiative and nonradiative recombination mechanisms in device-level LED numerical models.

Calciati, Marco; Vallone, Marco; Zhou, Xiangyu; Ghione, Giovanni [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); Goano, Michele, E-mail: michele.goano@polito.it; Bertazzi, Francesco [Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); IEIIT-CNR, Politecnico di Torino, corso Duca degli Abruzzi 24, 10129 Torino (Italy); Meneghini, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico [Dipartimento di Ingegneria dell'Informazione, Universit di Padova, Via Gradenigo 6/B, 35131 Padova (Italy); Bellotti, Enrico [Department of Electrical and Computer Engineering, Boston University, 8 Saint Mary's Street, 02215 Boston, MA (United States); Verzellesi, Giovanni [Dipartimento di Scienze e Metodi dell'Ingegneria, Universit di Modena e Reggio Emilia, 42122 Reggio Emilia (Italy); Zhu, Dandan; Humphreys, Colin [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

2014-06-15T23:59:59.000Z

440

Comparative study of field-dependent carrier dynamics and emission kinetics of InGaN/GaN light-emitting diodes grown on (11 2 2) semipolar versus (0001) polar  

E-Print Network [OSTI]

Articles you may be interested in Ultraviolet light-emitting diodes grown by plasma-assisted molecular beam light-emitting diodes prepared on ( 11 2 ¯ 2 ) -plane GaN J. Appl. Phys. 100, 113109 (2006); 10.1063/1.2382667 Demonstration of a semipolar ( 10 1 ¯ 3 ¯ ) In Ga N Ga N green light emitting diode Appl. Phys. Lett. 87, 231110

Demir, Hilmi Volkan

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Direct measurements of large near-band edge nonlinear index change from 1.48 to 1.55 m in InGaAsInAlGaAs multiquantum wells  

E-Print Network [OSTI]

used to measure di- rectly the nonlinear index change in bulk InGaAsP.10 Com- parison of DFWM results measurements of nonlinear refractive index change and nonlinear absorption in In0.530Al0.141Ga0.329As/In0.530Ga . The index-change-over-absorption figure of merit, F, is greater than unity over much of the spectrum

442

Polarized photoluminescence excitation spectroscopy of a-plane InGaN/GaN multiple quantum wells grown on r-plane sapphire  

SciTech Connect (OSTI)

We have performed a detailed study of the impact of basal plane stacking faults (BSFs) on the optical properties of both a-plane InGaN/GaN quantum wells (QWs) and GaN template samples grown on r-sapphire. In particular, we have used polarised photoluminescence excitation spectroscopy (P-PLE) to investigate the nature of the low temperature recombination as well as extracting information on the valence band (VB) polarisation anisotropy. Our low temperature P-PLE results revealed not only excitons associated with intersubband quantum well transitions and the GaN barrier material but also a transition associated with creation of excitons in BSFs. The strength of this BSF transition varied with detection energy across the quantum well emission suggesting that there is a significant contribution to the emission line width from changes in the local electronic environment of the QWs due to interactions with BSFs. Furthermore, we observed a corresponding progressive increase in the VB splitting of the QWs as the detection energy was varied across the quantum well emission spectrum.

Kundys, D., E-mail: dmytro.kundys@manchester.ac.uk; Sutherland, D.; Badcock, T. J.; Dawson, P. [School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Schulz, S. [Photonics Theory group, Tyndall National Institute, Lee Maltings, Cork (Ireland); Oehler, F.; Kappers, M. J.; Oliver, R. A.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS (United Kingdom)

2014-03-21T23:59:59.000Z

443

ELSEWER Journal of Magnetism and Magnetic Materials 169 (1997) 261-270 Superparamagnetic behavior of Fe,GaAs precipitates in GaAs  

E-Print Network [OSTI]

ELSEWER Journal of Magnetism and Magnetic Materials 169 (1997) 261-270 Superparamagnetic behavior; revised 6 December 1996 Abstract We present magnetization measurements on Fe3GaAs clusters distributed-dependent magnetization well above the blocking temperature indicate a particle size distribution in agreement

Woodall, Jerry M.

444

Rapid silicon outdiffusion from SiC substrates during molecular-beam epitaxial growth of AlGaN/GaN/AlN transistor structures  

SciTech Connect (OSTI)

AlGaN/GaN/AlN transistor structures were grown onto SiC substrates by molecular-beam epitaxy. Under aluminum-rich growth conditions for the AlN nucleation layer, undesirable n-type conduction is observed near the GaN/AlN interface for even thick (>1000 A) AlN layers. Silicon is identified as the unwanted dopant from secondary-ion mass spectroscopy measurements. Atomic force microscopy surface maps reveal free aluminum metal on AlN surfaces grown under modest aluminum-rich conditions. It is proposed that rapid silicon migration is caused by molten aluminum reacting with the SiC substrate resulting in dissolved silicon that rapidly migrates through the growing AlN layer. This behavior is significantly reduced using a growth flux ratio of aluminum to reactive nitrogen close to unity. The resulting buffer leakage current of the GaN high electron mobility transistor structure is reduced by more than four orders of magnitude.

Hoke, W.E.; Torabi, A.; Mosca, J.J.; Hallock, R.B.; Kennedy, T.D. [Raytheon RF Components, 362 Lowell Street, Andover, Massachusetts 01810 (United States)

2005-10-15T23:59:59.000Z

445

Journal of Crystal Growth 310 (2008) 23202325 Self-assembled InGaN quantum dots on GaN emitting at 520 nm grown  

E-Print Network [OSTI]

materials, and intrinsic quantum mechanical energy loss of the wavelength conversion process via Stokes, Muhammad Jamil, Nelson Tansu Department of Electrical and Computer Engineering, Center for Optical. These results demonstrates that high In-content InGaN QDs can be grown by MOVPE, and can potentially be utilized

Gilchrist, James F.

2008-01-01T23:59:59.000Z

446

Quasi-bound states and continuum absorption background of polar Al{sub 0.5}Ga{sub 0.5}N/GaN quantum dots  

SciTech Connect (OSTI)

A theoretical interpretation of the photoluminescence excitation spectra of self-organized polar GaN/(Al,Ga)N quantum dots is presented. A numerical method assuming a realistic shape of the dots and including the built-in electric field effects is developed to calculate their energy structure and hence their optical absorption. The electron and hole spectra show the existence of a set of quasi-bound states that does not originate from the wetting layer and plays a crucial role in the observed absorption spectrum of the GaN/(Al,Ga)N dots. Transitions involving these quasi-bound states and wetting layer states give a sufficient explanation for the observed continuum absorption background. The properties of this absorption band, especially its extension, depend strongly on the dot's size. Our simulation provides a natural explanation of the experimental luminescence excitation spectra of ensembles of dots of different heights. Our theoretical model can be convenient for future optical studies including systems with more complicated potentials.

Elmaghraoui, D., E-mail: elmaghraouidonia@yahoo.fr; Triki, M. [Laboratoire de physique de la matire condens, Facult des sciences de Tunis, Campus universitaire 2092 El Manar (Tunisia); Jaziri, S. [Laboratoire de physique de la matire condens, Facult des sciences de Tunis, Campus universitaire 2092 El Manar (Tunisia); Laboratoire de Physique des Matriaux, Facult des Sciences de Bizerte 7021 Jarzouna (Tunisia); Leroux, M.; Brault, J. [Centre de Recherche sur l'Hetero-Epitaxie et ses Applications, Centre National de la Recherche Scientifique, Rue B. Gregory, 06560 Valbonne (France)

2014-07-07T23:59:59.000Z

447

Low temperature thin film transistors with hollow cathode plasma-assisted atomic layer deposition based GaN channels  

SciTech Connect (OSTI)

We report GaN thin film transistors (TFT) with a thermal budget below 250?C. GaN thin films are grown at 200?C by hollow cathode plasma-assisted atomic layer deposition (HCPA-ALD). HCPA-ALD-based GaN thin films are found to have a polycrystalline wurtzite structure with an average crystallite size of 9.3?nm. TFTs with bottom gate configuration are fabricated with HCPA-ALD grown GaN channel layers. Fabricated TFTs exhibit n-type field effect characteristics. N-channel GaN TFTs demonstrated on-to-off ratios (I{sub ON}/I{sub OFF}) of 10{sup 3} and sub-threshold swing of 3.3?V/decade. The entire TFT device fabrication process temperature is below 250?C, which is the lowest process temperature reported for GaN based transistors, so far.

Bolat, S., E-mail: bolat@ee.bilkent.edu.tr, E-mail: aokyay@ee.bilkent.edu.tr; Tekcan, B. [Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800 (Turkey); UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Ozgit-Akgun, C.; Biyikli, N. [UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Okyay, A. K., E-mail: bolat@ee.bilkent.edu.tr, E-mail: aokyay@ee.bilkent.edu.tr [Department of Electrical and Electronics Engineering, Bilkent University, Ankara 06800 (Turkey); UNAM, National Nanotechnology Research Center, Bilkent University, Ankara 06800 (Turkey); Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey)

2014-06-16T23:59:59.000Z

448

Officers and Editors for 2011 JOSEPH R. MENDELSON III  

E-Print Network [OSTI]

Officers and Editors for 2011 President JOSEPH R. MENDELSON III Zoo Atlanta Atlanta, GA 30315, USA) Smithsonian Institution, USA TIFFANY DOAN (2014 R) Central Connecticut State Univ., USA PATRICK GREGORY (2012 PATERSON (2012 R) Williams Baptist College, USA JENNIFER PRAMUK (2014 Cons) Woodland Park Zoo, USA CAROL

Galn, Pedro

449

FLUID DYNAMIC ASPECTS OF THE POROUS WETTED WALL PROTECTION SCHEME FOR IFE REACTORS  

E-Print Network [OSTI]

FLUID DYNAMIC ASPECTS OF THE POROUS WETTED WALL PROTECTION SCHEME FOR IFE REACTORS S. Shin, F of Mechanical Engineering Georgia Institute of Technology Atlanta, GA 30332-0405 USA Number of Pages: 18 Number. Abdel-Khalik School of Mechanical Engineering Georgia Institute of Technology 771 Ferst Drive Atlanta

450

Recent progress in GaInAsSb thermophotovoltaics grown by organometallic vapor phase epitaxy  

SciTech Connect (OSTI)

Studies on the materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for thermophotovoltaic (TPV) devices are reviewed. Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} epilayers were grown lattice matched to GaSb substrates by organometallic vapor phase epitaxy (OMVPE) using all organometallic precursors including triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony with diethyltellurium and dimethylzinc as the n- and p-type dopants, respectively. The overall material quality of these alloys depends on growth temperature, In content, V/III ratio, substrate misorientation, and to a lesser extent, growth rate. A mirror-like surface morphology and room temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 and 2.5 {micro}m. The crystal quality improves for growth temperature decreasing from 575 to 525 C, and with decreasing In content, as based on epilayer surface morphology and low temperature PL spectra. A trend of smaller full width at half-maximum for low temperature PL spectra is observed as the growth rate is increased from 1.5 to 2.5 and 5 {micro}m/h. In general, GaInAsSb layers grown on (100) GaSb substrates with a 6{degree} toward (111)B misorientation exhibited overall better material quality than layers grown on the more standard substrate (100)2{degree} toward (110). Consistent growth of high performance lattice-matched GaInAsSb TPV devices is also demonstrated.

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

1998-06-01T23:59:59.000Z

451

OMVPE growth and characterization of GaInAsSb for thermophotovoltaics  

SciTech Connect (OSTI)

Studies on the materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for thermophotovoltaic (TPV) devices are reviewed. Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} epilayers were grown lattice matched to GaSb substrates by organometallic vapor phase epitaxy (OMVPE) using all organometallic precursors including triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony with diethyltellurium and dimethylzinc as the n- and p-type dopants, respectively. The overall material quality of these alloys depends on growth temperature, In content, V/III ratio, substrate misorientation, and to a lesser extent, growth rate. A mirror-like surface morphology and room temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 and 2.5 {micro}m. The crystal quality improves for growth temperature decreasing from 575 to 525 C, and with decreasing In content, as based on epilayer surface morphology and low temperature PL spectra. A trend of smaller full width at half-maximum for low temperature PL spectra is observed as the growth rate is increased from 1.5 to 2.5 and 5 {micro}m/h. In general, GaInAsSb layers grown on (100) GaSb substrates with a 6{degree} toward (111)B misorientation exhibited overall better material quality than layers grown on the more standard substrate (100) 2{degree} toward (110). Consistent growth of high performance lattice-matched GaInAsSb TPV devices is also demonstrated.

Wang, C.A.; Charache, G.W.

1998-06-01T23:59:59.000Z

452

Deposition of CVD diamond onto GaN P.W. May a,*, H.Y. Tsai b  

E-Print Network [OSTI]

of the polycrystalline diamond surface would prevent light from leaking out of the GaN layer and channel it to the endsDeposition of CVD diamond onto GaN P.W. May a,*, H.Y. Tsai b , W.N. Wang c , J.A. Smith a a School performed to deposit continuous layers of CVD diamond onto epitaxial GaN films. Such diamond coatings would

Bristol, University of

453

Photoluminescence study of the 1.047 eV emission in GaN K. Pressela)  

E-Print Network [OSTI]

GaN/ AlGaN blue green light emitting diode, which has a much higher quantum efficiency than the SiC blue light emitting diode, became possible.2 Presently the wide bandgap semi- conductor GaN is intensively. Especially the 1.19 eV is very intense. Thus one can think of developing a light emitting diode in the near

Nabben, Reinhard

454

Nonlinear absorption edge properties of 1.3-m GaInNAs saturable R. Grange,a  

E-Print Network [OSTI]

-starting and stable operation of the laser at tens of GHz repetition rates.4 So far, InGaAsP,5 InGaAs,6,7 and AlNonlinear absorption edge properties of 1.3- m GaInNAs saturable absorbers R. Grange,a A. Rutz, V above the PL peak and R scales with the linear absorption even in the bandtail. The product R

Keller, Ursula

455

Structure and strain-relaxation effects of defects in InxGa1-xN epilayers  

E-Print Network [OSTI]

The direct band gap of InxGa1-xN can be engineered to emit light over the entire visible spectrum depending on the In content (x) of the film. InGaN-based alloys are thereby used to fabricate light-emitting diodes (LEDs), laser diodes (LDs) [1] [2... ] and solar cells [3] [4]. InGaN alloys are excellent candidates for the light-absorption layers in solar cell applications because of their high-energy radiation resistance [3] and because InGaN alloys across the 2 range of In compositions absorb light...

Rhode, S. L.; Fu, W. Y.; Moram, M. A.; Massabuau, F. C.-P.; Kappers, M. J.; McAleese, C.; Oehler, F.; Humphreys, C. J.; Dusane, R. O.; Sahonta, S.-L.

2014-09-10T23:59:59.000Z

456

Physics based analytical modelling of Gallium Nitride(GaN) MESFET considering different ion implantation energy with high temperature annealing.  

E-Print Network [OSTI]

??A physics based analytical model of ion implanted GaN MESFET has been presented considering high temperature annealing effects. Choosing appropriate activation energy of impurity atoms, (more)

Raghavan, Vinay

2015-01-01T23:59:59.000Z

457

Nanostructural engineering of nitride nucleation layers for GaN substrate dislocation reduction.  

SciTech Connect (OSTI)

With no lattice matched substrate available, sapphire continues as the substrate of choice for GaN growth, because of its reasonable cost and the extensive prior experience using it as a substrate for GaN. Surprisingly, the high dislocation density does not appear to limit UV and blue LED light intensity. However, dislocations may limit green LED light intensity and LED lifetime, especially as LEDs are pushed to higher current density for high end solid state lighting sources. To improve the performance for these higher current density LEDs, simple growth-enabled reductions in dislocation density would be highly prized. GaN nucleation layers (NLs) are not commonly thought of as an application of nano-structural engineering; yet, these layers evolve during the growth process to produce self-assembled, nanometer-scale structures. Continued growth on these nuclei ultimately leads to a fully coalesced film, and we show in this research program that their initial density is correlated to the GaN dislocation density. In this 18 month program, we developed MOCVD growth methods to reduce GaN dislocation densities on sapphire from 5 x 10{sup 8} cm{sup -2} using our standard delay recovery growth technique to 1 x 10{sup 8} cm{sup -2} using an ultra-low nucleation density technique. For this research, we firmly established a correlation between the GaN nucleation thickness, the resulting nucleation density after annealing, and dislocation density of full GaN films grown on these nucleation layers. We developed methods to reduce the nuclei density while still maintaining the ability to fully coalesce the GaN films. Ways were sought to improve the GaN nuclei orientation by improving the sapphire surface smoothness by annealing prior to the NL growth. Methods to eliminate the formation of additional nuclei once the majority of GaN nuclei were developed using a silicon nitride treatment prior to the deposition of the nucleation layer. Nucleation layer thickness was determined using optical reflectance and the nucleation density was determined using atomic force microscopy (AFM) and Nomarski microscopy. Dislocation density was measured using X-ray diffraction and AFM after coating the surface with silicon nitride to delineate all dislocation types. The program milestone of producing GaN films with dislocation densities of 1 x 10{sup 8} cm{sup -2} was met by silicon nitride treatment of annealed sapphire followed by the multiple deposition of a low density of GaN nuclei followed by high temperature GaN growth. Details of this growth process and the underlying science are presented in this final report along with problems encountered in this research and recommendations for future work.

Koleske, Daniel David; Lee, Stephen Roger; Lemp, Thomas Kerr; Coltrin, Michael Elliott; Cross, Karen Charlene; Thaler, Gerald

2009-07-01T23:59:59.000Z

458

GaSb based ternary and quaternary diffused junction devices for TPV applications  

SciTech Connect (OSTI)

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

Sundaram, V.S.; Saban, S.B.; Morgan, M.D.; Horne, W.E.; Evans, B.D.; Ketterl, J.R. [EDTEK Inc. 7082 S. 220th Street Kent, Washington 98032 (United States); Morosini, M.B.; Patel, N.B. [Instituto de Fisica, UNICAMP, Campinas, Brasil (Brazil); Field, H. [NREL, Golden, Colorado (United States)

1997-03-01T23:59:59.000Z

459

HfO{sub x}N{sub y} gate dielectric on p-GaAs  

SciTech Connect (OSTI)

Plasma nitridation method is used for nitrogen incorporation in HfO{sub 2} based gate dielectrics for future GaAs-based devices. The nitrided HfO{sub 2} (HfO{sub x}N{sub y}) films on p-GaAs improve metal-oxide-semiconductor device characteristics such as interface state density, accumulation capacitance, hysteresis, and leakage current. An equivalent oxide thickness of 3.6 nm and a leakage current density of 10{sup -6} A cm{sup -2} have been achieved at V{sub FB}-1 V for nitrided HfO{sub 2} films. A nitride interfacial layer (GaAsO:N) was observed at HfO{sub 2}-GaAs interface, which can reduce the outdiffusion of elemental Ga and As during post-thermal annealing process. Such suppression of outdiffusion led to a substantial enhancement in the overall dielectric properties of the HfO{sub 2} film.

Dalapati, G. K.; Sridhara, A.; Wong, A. S. W.; Chia, C. K.; Chi, D. Z. [Institute of Materials Research and Engineering, A-STAR - Agency for Science, Technology and Research, 3 Research Link, Singapore 117602 (Singapore)

2009-02-16T23:59:59.000Z

460

Lattice-registered growth of GaSb on Si (211) with molecular beam epitaxy  

SciTech Connect (OSTI)

A GaSb film was grown on a Si(211) substrate using molecular beam epitaxy indicating full lattice relaxation as well as full lattice registration and dislocation-free growth in the plane perpendicular to the [01 - 1]-direction. Heteroepitaxy of GaSb on a Si(211) substrate is dominated by numerous first order and multiple higher order micro-twins. The atomic-resolved structural study of GaSb films by high-angle annular dark-field scanning transmission electron microscopy reveals that slight tilt, along with twinning, favors the lattice registry to Si(211) substrates. Preferential bonding of impinging Ga and Sb atoms at the interface due to two distinctive bonding sites on the Si(211) surface enables growth that is sublattice-ordered and free of anti-phase boundaries. The role of the substrate orientation on the strain distribution of GaSb epilayers is further elucidated by investigating the local change in the lattice parameter using the geometric phase analysis method and hence effectiveness of the lattice tilting in reducing the interfacial strain was confirmed further.

Hosseini Vajargah, S.; Botton, G. A. [Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Ghanad-Tavakoli, S. [Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Preston, J. S.; Kleiman, R. N. [Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)

2012-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

GaAs Blocked-Impurity-Band Detectors for Far-Infrared Astronomy  

SciTech Connect (OSTI)

High-purity and doped GaAs films have been grown by Liquid-phase epitaxy (LPE) for development of a blocked impurity band (BIB) detector for far-infrared radiation. The film growth process developed has resulted in the capability to grow GaAs with a net active impurity concentration below 1 x 10{sup 13} cm{sup -3}, ideal for the blocking layer of the BIB detector. The growth of n-type LPE GaAs films with donor concentrations below the metal-insulator transition, as required for the absorbing layer of a BIB detector, has been achieved. The control of the donor concentration, however, was found to be insufficient for detector production. The growth by LPE of a high-purity film onto a commercially grown vapor-phase epitaxial (VPE) n-type GaAs doped absorbing layer resulted in a BIB device that showed a significant reduction in the low-temperature dark current compared to the absorbing layer only. Extended optical response was not detected, most likely due to the high compensation of the commercially grown GaAs absorbing layer, which restricts the depletion width of the device.

Cardozo, Benjamin Lewin

2004-12-21T23:59:59.000Z

462

Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes  

SciTech Connect (OSTI)

We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)] [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2013-01-28T23:59:59.000Z

463

Growth and characterization of dilute nitride GaN{sub x}P{sub 1?x} nanowires and GaN{sub x}P{sub 1?x}/GaN{sub y}P{sub 1?y} core/shell nanowires on Si (111) by gas source molecular beam epitaxy  

SciTech Connect (OSTI)

We have demonstrated self-catalyzed GaN{sub x}P{sub 1?x} and GaN{sub x}P{sub 1?x}/GaN{sub y}P{sub 1?y} core/shell nanowire growth by gas-source molecular beam epitaxy. The growth window for GaN{sub x}P{sub 1?x} nanowires was observed to be comparable to that of GaP nanowires (?585?C to ?615?C). Transmission electron microscopy showed a mixture of cubic zincblende phase and hexagonal wurtzite phase along the [111] growth direction in GaN{sub x}P{sub 1?x} nanowires. A temperature-dependent photoluminescence (PL) study performed on GaN{sub x}P{sub 1?x}/GaN{sub y}P{sub 1?y} core/shell nanowires exhibited an S-shape dependence of the PL peaks. This suggests that at low temperature, the emission stems from N-related localized states below the conduction band edge in the shell, while at high temperature, the emission stems from band-to-band transition in the shell as well as recombination in the GaN{sub x}P{sub 1?x} core.

Sukrittanon, S. [Graduate Program of Material Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Kuang, Y. J. [Department of Physics, University of California, San Diego, La Jolla, California 92037 (United States); Dobrovolsky, A.; Chen, W. M.; Buyanova, I. A. [Department of Physics, Chemistry and Biology, Linkping University, 581 83 Linkping (Sweden); Kang, Won-Mo; Kim, Bong-Joong [Department of Materials Science and Engineering, Gwangju institute of Science and Technology (GIST), Gwangju 500-712 (Korea, Republic of); Jang, Ja-Soon [Department of Electronic Engineering, LED-IT Fusion Technology Research Center, Yeungnam University, Daegu 712-749 (Korea, Republic of); Tu, C. W. [Graduate Program of Material Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States)

2014-08-18T23:59:59.000Z

464

Influence of growth temperature and temperature ramps on deep level defect incorporation in m-plane GaN  

SciTech Connect (OSTI)

The dependence of deep level defect incorporation in m-plane GaN films grown by metal-organic chemical vapor deposition on bulk m-plane GaN substrates as a function of growth temperature (T{sub g}) and T{sub g} ramping method was investigated using deep level optical spectroscopy. Understanding the influence of T{sub g} on GaN deep level incorporation is important for InGaN/GaN multi-quantum well (MQW) light emitting diodes (LEDs) and laser diodes (LDs) because GaN quantum barrier (QB) layers are grown much colder than thin film GaN to accommodate InGaN QW growth. Deep level spectra of low T{sub g} (800?C) GaN films grown under QB conditions were compared to deep level spectra of high T{sub g} (1150?C) GaN. Reducing T{sub g}, increased the defect density significantly (>50) through introduction of emergent deep level defects at 2.09?eV and 2.9?eV below the conduction band minimum. However, optimizing growth conditions during the temperature ramp when transitioning from high to low T{sub g} substantially reduced the density of these emergent deep levels by approximately 40%. The results suggest that it is important to consider the potential for non-radiative recombination in QBs of LED or LD active regions, and tailoring the transition from high T{sub g} GaN growth to active layer growth can mitigate such non-radiative channels.

Armstrong, A. M., E-mail: aarmstr@sandia.gov [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Kelchner, K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)] [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Nakamura, S.; DenBaars, S. P. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States) [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Department, University of California, Santa Barbara, California 93106 (United States); Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States)] [Materials Department, University of California, Santa Barbara, California 93106 (United States)

2013-12-02T23:59:59.000Z

465

Recrystallization method to selenization of thin-film Cu(In,Ga)Se.sub.2 for semiconductor device applications  

DOE Patents [OSTI]

A process for fabricating slightly Cu-poor thin-films of Cu(In,Ga)Se.sub.2 on a substrate for semiconductor device applications includes the steps of forming initially a slightly Cu-rich, phase separated, mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se on the substrate in solid form followed by exposure of the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture to an overpressure of Se vapor and (In,Ga) vapor for deposition on the Cu(In,Ga)Se.sub.2 :Cu.sub.x Se solid mixture while simultaneously increasing the temperature of the solid mixture toward a recrystallization temperature (about 550.degree. C.) at which Cu(In,Ga)Se.sub.2 is solid and Cu.sub.x Se is liquid. The (In,Ga) flux is terminated while the Se overpressure flux and the recrystallization temperature are maintained to recrystallize the Cu.sub.x Se with the (In, Ga) that was deposited during the temperature transition and with the Se vapor to form the thin-film of slightly Cu-poor Cu.sub.x (In,Ga).sub.y Se.sub.z. The initial Cu-rich, phase separated large grain mixture of Cu(In,Ga)Se.sub.2 :Cu.sub.x Se can be made by sequentially depositing or co-depositing the metal precursors, Cu and (In, Ga), on the substrate at room temperature, ramping up the thin-film temperature in the presence of Se overpressure to a moderate anneal temperature (about 450.degree. C.) and holding that temperature and the Se overpressure for an annealing period. A nonselenizing, low temperature anneal at about 100.degree. C. can also be used to homogenize the precursors on the substrates before the selenizing, moderate temperature anneal.

Albin, David S. (Denver, CO); Carapella, Jeffrey J. (Evergreen, CO); Tuttle, John R. (Denver, CO); Contreras, Miguel A. (Golden, CO); Gabor, Andrew M. (Boulder, CO); Noufi, Rommel (Golden, CO); Tennant, Andrew L. (Denver, CO)

1995-07-25T23:59:59.000Z

466

Ab initio density functional theory study of non-polar (101{sup }0),?(112{sup }0) and semipolar (202{sup }1) GaN surfaces  

SciTech Connect (OSTI)

The atomic structures of non-polar GaN(101{sup }0),?(112{sup }0) and semipolar GaN(202{sup }1),?(202{sup }1{sup }) surfaces were studied using ab initio calculations within density functional theory. The bulk-like truncated (1??1) structure with buckled Ga-N or Ga-Ga dimers was found stable on the non-polar GaN(101{sup }0) surface in agreement with previous works. Ga-N heterodimers were found energetically stable on the GaN(112{sup }0)-(1??1) surface. The formation of vacancies and substitution site defects was found unfavorable for non-polar GaN surfaces. Semipolar GaN(202{sup }1)-(1??1) surface unit cells consist of non-polar (101{sup }0) and semipolar (101{sup }1) nano-facets. The (101{sup }1) nano-facets consist of two-fold coordinated atoms, which form N-N dimers within a (2??1) surface unit cell on a GaN(202{sup }1) surface. Dimers are not formed on the GaN(202{sup }1{sup }) surface. The stability of the surfaces with single (101{sup }0) or (101{sup }1) nano-facets was analyzed. A single non-polar (101{sup }0)-(1??1) nano-facet was found stable on the GaN(202{sup }1) surface, but unstable on the GaN(202{sup }1{sup }) surface. A single (101{sup }1) nano-facet was found unstable. Semipolar GaN surfaces with (202{sup }1) and (202{sup }1{sup }) polarity can be stabilized with a Ga overlayer at Ga-rich experimental conditions.

Mutombo, P.; Romanyuk, O., E-mail: romanyuk@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnick 10, 16200 Prague (Czech Republic)

2014-05-28T23:59:59.000Z

467

Photoluminescence of GaAs films grown by vacuum chemical epitaxy  

SciTech Connect (OSTI)

GaAs layers grown by vacuum chemical epitaxy (VCE) are investigated by low-temperature photoluminescence. A qualitative relation between the growth parameters and the shallow-impurity-incorporation mechanism is established. It was observed that the predominant shallow acceptor is carbon, and its incorporation during the growth process decreases with the As:Ga ratio, increases with growth temperature until 750 /sup 0/C, and then it diminishes. In this work we compare the characteristics observed in the VCE system with those in conventional molecular-beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). Our results show that this system contains some advantages from both the MBE and MOCVD systems. The photoluminescence spectra also show that at low As:Ga ratios the generation of As vacancies or its complexes is strongly enhanced.

Bernussi, A.A.; Barreto, C.L.; Carvalho, M.M.G.; Motisuke, P.

1988-08-01T23:59:59.000Z

468

Origin of background electron concentration in InxGa1-xN alloys  

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

The origin of high background electron concentration (n) in InxGa1-xN alloys has been investigated. A shallow donor was identified as having an energy level (ED1) that decreases with x (ED1 = 16 meV at x = 0 and ED1 = 0 eV at x ~ 0.5) and that crossover the conduction band at x ~ 0.5. This shallow donor is believed to be the most probable cause of high n in InGaN. This understanding is consistent with the fact that n increases sharply with an increase in x and becomes constant for x > 0.5. A continuous reduction in n was obtained by increasing the V/III ratio during the epilayer growth, suggesting that nitrogen vacancy-related impurities are a potential cause of the shallow donors and high background electron concentration in InGaN

Pantha, B. N.; Wang, H.; Khan, N.; Lin, J. Y.; Jiang, H. X.

2011-08-01T23:59:59.000Z

469

Band offsets in HfO{sub 2}/InGaZnO{sub 4} heterojunctions  

SciTech Connect (OSTI)

The valence band discontinuity ({Delta}E{sub V}) of sputter deposited HfO{sub 2}/InZnGaO{sub 4} (IGZO) heterostructures was obtained from x-ray photoelectron spectroscopy measurements. The HfO{sub 2} exhibited a bandgap of 6.07 eV from absorption measurements. A value of {Delta}E{sub V} = 0.48 {+-} 0.025 eV was obtained by using the Ga 2p{sub 3/2}, Zn 2p{sub 3/2}, and In 3d{sub 5/2} energy levels as references. This implies a conduction band offset {Delta}E{sub C} of 2.39 eV in HfO{sub 2}/InGaZnO{sub 4} heterostructures and a nested interface band alignment.

Cho, Hyun [Department of Nanomechatronics Engineering, Pusan National University, Gyeongnam 627-706 (Korea, Republic of); Douglas, E. A.; Gila, B. P.; Craciun, V.; Lambers, E. S.; Pearton, S. J. [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Ren Fan [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

2012-01-02T23:59:59.000Z

470

Strong light-matter coupling in ultrathin double dielectric mirror GaN microcavities  

SciTech Connect (OSTI)

Strong light-matter coupling is demonstrated at low temperature in an ultrathin GaN microcavity fabricated using two silica/zirconia Bragg mirrors, in addition to a three-period epitaxial (Al,Ga)N mirror serving as an etch stop and assuring good quality of the overgrown GaN. The {lambda}/2 cavity is grown by molecular beam epitaxy on a Si substrate. Analysis of angle-resolved data reveal key features of the strong coupling regime in both reflectivity and transmission spectra at 5 K: anticrossing with a normal mode splitting of 43{+-}2 meV and 56{+-}2 meV for reflectivity and transmission, respectively, and narrowing of the lower polariton linewidth near resonance.

Bejtka, K.; Martin, R. W. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France); Reveret, F.; Vasson, A.; Leymarie, J. [LASMEA, UMR 6602 UBP/CNRS, 24 Avenue des Landais, F-63177 Aubiere Cedex (France); Edwards, P. R. [Department of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Sellers, I. R.; Duboz, J. Y.; Leroux, M.; Semond, F. [CRHEA-CNRS, Rue Bernard Gregory, Parc Sophia Antipolis, 06560 Valbonne (France)

2008-06-16T23:59:59.000Z

471

Thermoelectric characteristic of the rough InN/GaN core-shell nanowires  

SciTech Connect (OSTI)

An analysis to model the thermoelectric (TE) effects of the rough InN/GaN core-shell nanowires (NWs) with wire diameter ranging from 25?nm to 100?nm is proposed. The elastic continuum model is employed to calculate the phonon dispersion relation curves and the related phonon group velocity. Within the framework of Boltzmann transport equations and relaxation time approximation, the electrical conductivity, Seebeck coefficient, electronic thermal conductivity, and the lattice thermal conductivity is obtained. Simulation results indicate that TE properties of the rough InN/GaN core-shell NWs are strongly affected by the surface roughness and the diameter of NWs. The optimized condition of the proposed rough InN/GaN core-shell TE NWs is studied in this paper and the highest ZT obtained in the calculation is 0.8598 at 300?K and 1.713 at 1000?K.

Wu, Chao-Wei; Wu, Yuh-Renn, E-mail: yrwu@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

2014-09-14T23:59:59.000Z

472

Axial strain in GaAs/InAs core-shell nanowires  

SciTech Connect (OSTI)

We study the axial strain relaxation in GaAs/InAs core-shell nanowire heterostructures grown by molecular beam epitaxy. Besides a gradual strain relaxation of the shell material, we find a significant strain in the GaAs core, increasing with shell thickness. This strain is explained by a saturation of the dislocation density at the core-shell interface. Independent measurements of core and shell lattice parameters by x-ray diffraction reveal a relaxation of 93% in a 35 nm thick InAs shell surrounding cores of 80 nm diameter. The compressive strain of -0.5% compared to bulk InAs is accompanied by a tensile strain up to 0.9% in the GaAs core.

Biermanns, Andreas; Pietsch, Ullrich [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany)] [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany); Rieger, Torsten; Gruetzmacher, Detlev; Ion Lepsa, Mihail [Peter Gruenberg Institute (PGI-9), Forschungszentrum, 52425 Juelich (Germany) [Peter Gruenberg Institute (PGI-9), Forschungszentrum, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technology, 52425 Juelich (Germany); Bussone, Genziana [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany) [Universitaet Siegen, Festkoerperphysik, 57068 Siegen (Germany); ESRF, 6 rue Jules Horowitz, BP220, F-38043 Grenoble Cedex (France)

2013-01-28T23:59:59.000Z

473

Growth and properties of crystalline barium oxide on the GaAs(100) substrate  

SciTech Connect (OSTI)

Growing a crystalline oxide film on III-V semiconductor renders possible approaches to improve operation of electronics and optoelectronics heterostructures such as oxide/semiconductor junctions for transistors and window layers for solar cells. We demonstrate the growth of crystalline barium oxide (BaO) on GaAs(100) at low temperatures, even down to room temperature. Photoluminescence (PL) measurements reveal that the amount of interface defects is reduced for BaO/GaAs, compared to Al{sub 2}O{sub 3}/GaAs, suggesting that BaO is a useful buffer layer to passivate the surface of the III-V device material. PL and photoemission data show that the produced junction tolerates the post heating around 600?C.

Yasir, M.; Dahl, J.; Lng, J.; Tuominen, M.; Punkkinen, M. P. J.; Laukkanen, P., E-mail: pekka.laukkanen@utu.fi; Kokko, K. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland)] [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Kuzmin, M. [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland) [Department of Physics and Astronomy, University of Turku, FI-20014 Turku (Finland); Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Korpijrvi, V.-M.; Polojrvi, V.; Guina, M. [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland)] [Optoelectronics Research Centre, Tampere University of Technology, FI-33101 Tampere (Finland)

2013-11-04T23:59:59.000Z

474

Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells  

SciTech Connect (OSTI)

InAs/GaAs strain-balanced quantum dot (QD) n-i-p solar cells were fabricated by epitaxial lift-off (ELO), creating thin and flexible devices that exhibit an enhanced sub-GaAs bandgap current collection extending into the near infrared. Materials and optical analysis indicates that QD quality after ELO processing is preserved, which is supported by transmission electron microscopy images of the QD superlattice post-ELO. Spectral responsivity measurements depict a broadband resonant cavity enhancement past the GaAs bandedge, which is due to the thinning of the device. Integrated external quantum efficiency shows a QD contribution to the short circuit current density of 0.23?mA/cm{sup 2}.

Bennett, Mitchell F.; Bittner, Zachary S.; Forbes, David V.; Hubbard, Seth M., E-mail: smhsps@rit.edu [Rochester Institute of Technology, Rochester, New York 14623 (United States); Rao Tatavarti, Sudersena; Wibowo, Andree; Pan, Noren; Chern, Kevin [MicroLink Devices, Inc., Niles, Illinois 60714 (United States)] [MicroLink Devices, Inc., Niles, Illinois 60714 (United States); Phillip Ahrenkiel, S. [South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States)] [South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States)

2013-11-18T23:59:59.000Z

475

Epitaxial Growth of GaN-based LEDs on Simple Sacrificial Substrates  

SciTech Connect (OSTI)

The objective of this project is to produce alternative substrate technologies for GaN-based LEDs by developing an ALD interlayer of Al{sub 2}O{sub 3} on sacrificial substrates such as ZnO and Si. A sacrificial substrate is used for device growth that can easily be removed using a wet chemical etchant leaving only the thin GaN epi-layer. After substrate removal, the GaN LED chip can then be mounted in several different ways to a metal heat sink/reflector and light extraction techniques can then be applied to the chip and compared for performance. Success in this work will lead to high efficiency LED devices with a simple low cost fabrication method and high product yield as stated by DOE goals for its solid state lighting portfolio.

Ian Ferguson; Chris Summers

2009-12-31T23:59:59.000Z

476

Charge transfer in Fe-doped GaN: The role of the donor  

SciTech Connect (OSTI)

Several nitride-based device structures would benefit from the availability of high quality, large-area, freestanding semi-insulating GaN substrates. Due to the intrinsic n-type nature of GaN, however, the incorporation of compensating centers such as Fe is necessary to achieve the high resistivity required. We are using electron paramagnetic resonance (EPR) to explore charge transfer in 450 um thick GaN:Fe plates to understand the basic mechanisms related to compensation so that the material may be optimized for device applications. The results suggest that the simple model based on one shallow donor and a single Fe level is insufficient to describe compensation. Rather, the observation of the neutral donor and Fe3+ indicates that either the two species are spatially segregated or additional compensating and donor defects must be present.

Sunay, Ustun; Dashdorj, J.; Zvanut, M. E.; Harrison, J. G. [Department of Physics, University of Alabama at Birmingham, 1300 University Blvd., CH 310, Birmingham, Alabama 35294-1170 (United States); Leach, J. H.; Udwary, K. [Kyma Technologies, 8829 Midway West Rd., Raleigh, North Carolina 27617 (United States)

2014-02-21T23:59:59.000Z

477

Temperature behavior of optical absorption in InGaAsP lasers  

SciTech Connect (OSTI)

The temperature dependence of the optical absorption in InGaAsP laser emitting at 1.3 ..mu..m is studied by measuring the relaxation frequency as a function of output power at various temperatures. Our results show that the optical absorption does not vary significantly with increasing temperature. This suggests that the threshold carrier density in InGaAsP lasers is weakly temperature dependent compared to the threshold current density. Thus, the strong temperature dependence of threshold current in 1.3-..mu..m InGaAsP lasers is primarily due to the temperature dependence of the carrier lifetime at threshold. The shorter carrier lifetime (i.e., increased carrier loss) at high temperature can be due to Auger recombination.

Shen, T.M.; Dutta, N.K.

1984-12-15T23:59:59.000Z

478

Charge tuning in [111] grown GaAs droplet quantum dots  

SciTech Connect (OSTI)

We demonstrate charge tuning in strain free GaAs/AlGaAs quantum dots (QDs) grown by droplet epitaxy on a GaAs(111)A substrate. Application of a bias voltage allows the controlled charging of the QDs from ?3|e| to +2|e|. The resulting changes in QD emission energy and exciton fine-structure are recorded in micro-photoluminescence experiments at T?=?4?K. We uncover the existence of excited valence and conduction states, in addition to the s-shell-like ground state. We record a second series of emission lines about 25?meV above the charged exciton emission coming from excited charged excitons. For these excited interband transitions, a negative diamagnetic shift of large amplitude is uncovered in longitudinal magnetic fields.

Bouet, L.; Vidal, M.; Marie, X.; Amand, T.; Wang, G.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Universit de Toulouse, 135 Ave. Rangueil, 31077 Toulouse (France); Mano, T.; Ha, N.; Kuroda, T.; Sakoda, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Durnev, M. V.; Glazov, M. M.; Ivchenko, E. L. [Ioffe Physical-Technical Institute RAS, 194021 St.-Petersburg (Russian Federation)

2014-08-25T23:59:59.000Z

479

White light generation by resonant nonradiative energy transfer from epitaxial InGaN/GaN quantum wells to colloidal CdSe/ZnS core/shell quantum dots  

E-Print Network [OSTI]

White light generation by resonant nonradiative energy transfer from epitaxial InGaN/GaN quantum n a l f o r p h y s i c s New Journal of Physics White light generation by resonant nonradiative white-light-generating nonradiative energy transfer (ET) from epitaxial quantum wells (QWs) to colloidal

Demir, Hilmi Volkan

480

Ge doped GaN with controllable high carrier concentration for plasmonic applications  

SciTech Connect (OSTI)

Controllable Ge doping in GaN is demonstrated for carrier concentrations of up to 2.4??10{sup 20} cm{sup ?3}. Low temperature luminescence spectra from the highly doped samples reveal band gap renormalization and band filling (Burstein-Moss shift) in addition to a sharp transition. Infrared ellipsometry spectra demonstrate the existence of electron plasma with an energy around 3500?cm{sup ?1} and a surface plasma with an energy around 2000?cm{sup ?1}. These findings open possibilities for the application of highly doped GaN for plasmonic devices.

Kirste, Ronny; Hoffmann, Marc P.; Sachet, Edward; Bobea, Milena; Bryan, Zachary; Bryan, Isaac; Maria, Jon-Paul; Collazo, Ramn; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States)] [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States); Nenstiel, Christian; Hoffmann, Axel [Institut f?r Festkrperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)] [Institut f?r Festkrperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

2013-12-09T23:59:59.000Z

Note: This page contains sample records for the topic "atlanta ga dekalb" from the National Library of EnergyBeta (NLEBeta).
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481

Wafer-fused p-i-n InGaAs/Si photodiode with photogain  

SciTech Connect (OSTI)

Using high temperature fusion of InGaAs/InP on Si, we demonstrated an InGaAs/Si p-i-n photodiode with a photomultiplication gain of 11 at relatively low bias of -15 V. The photodiode exhibited a dark current of 30 nA at -5 V, and a responsivity of 0.3 A/W at 1.32 {mu}m wavelength without antireflection coating. The measured device behavior were consistent with that predicted by a model of charged interface states resulting from the fusion. {copyright} 2001 American Institute of Physics.

Kang, Y.; Mages, P.; Clawson, A. R.; Lau, S. S.; Lo, Y. H.; Yu, P. K. L.; Pauchard, A.; Zhu, Z.; Zhou, Y.

2001-08-13T23:59:59.000Z

482

X-ray detectors based on GaN Schottky diodes  

SciTech Connect (OSTI)

GaN Schottky diodes have been fabricated and tested as x-ray detectors in the range from 6 to 21 keV. The spectral response has been measured and is compared to its theoretical value. The study of the response and its temporal dynamics as a function of the bias allows to identify a photovoltaic behavior at low bias and a photoconductive one at larger reverse biases. The GaN diode turned out to be linear as a function of the incident power. The noise and detectivity are given and discussed.

Duboz, Jean-Yves; Frayssinet, Eric; Chenot, Sebastien [CRHEA, CNRS, Rue Bernard Gregory, Sophia Antipolis, F-06560 Valbonne (France); Reverchon, Jean-Luc [THALES R and T, Campus Polytechnique, 1 avenue Augustin Fresnel, F-91767 Palaiseau Cedex (France); Idir, Mourad [Synchrotron SOLEIL L'Orme des Merisiers, Saint-Aubin-BP 48 91192, GIF-sur-Yvette Cedex (France)

2010-10-18T23:59:59.000Z

483

Ionic conductivity and dielectric relaxation in {gamma}-irradiated TlGaTe{sub 2} crystals  

SciTech Connect (OSTI)

The switching effect, field and temperature dependences of the permittivity and conductivity of TlGaTe{sub 2} crystals subjected to various {gamma}-irradiation doses are studied. Under rather low electric fields, the phenomenon of threshold switching with an S-shaped current-voltage characteristic containing a portion with negative differential resistance is observed in the crystals. In the region of critical voltages, current and voltage oscillations and imposed modulation are observed. Possible mechanisms of switching, ionic conductivity, disorder, and electrical instability in TlGaTe{sub 2} crystals are discussed.

Sardarli, R. M., E-mail: sardarli@yahoo.com; Samedov, O. A.; Abdullayev, A. P. [National Academy of Sciences of Azerbaijan, Institute of Radiation Problems (Azerbaijan); Huseynov, E. K. [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan); Salmanov, F. T.; Alieva, N. A.; Agaeva, R. Sh. [National Academy of Sciences of Azerbaijan, Institute of Radiation Problems (Azerbaijan)

2013-05-15T23:59:59.000Z

484

Structure of {sup 81}Ga populated from the {beta}{sup -} decay of {sup 81}Zn  

SciTech Connect (OSTI)

We report on the results of the {beta}-decay of {sup 81}Zn. The experiment was performed at the CERN ISOLDE facility in the framework of a systematic ultra-fast timing investigation of neutron-rich nuclei populated in the decay of Zn. The present analysis included {beta}-gated {gamma}-ray singles and {gamma}-{gamma} coincidences from the decay of {sup 81}Zn to {sup 81}Ga and leads to a new and much more extensive level scheme of {sup 81}Ga. A new half-life of {sup 81}Zn is provided.

Paziy, V.; Mach, H.; Fraile, L. M.; Olaizola, B.; Udias, J. M. [Grupo de Fisica Nuclear, Universidad Complutense, Madrid (Spain); Aprahamian, A.; Bucher, B. [Department of Physics, University of Notre Dame (United States); Bernards, C. [Institut fuer Kernphysik, Koeln, Germany. and Wright Nuclear Structure Laboratory, Yale University, New Haven, CT-06520 (United States); Briz, J. A. [Instituto de Estructura de la Materia, CSIC, Madrid (Spain); Chiara, C. J. [Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland, USA. and Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Dlouhy, Z. [Nuclear Physics Institute of the ASCR, Rez (Czech Republic); Gheorghe, I.; Ghita, D.; Lica, R.; Marginean, N.; Marginean, R.; Stanoiu, M.; Stroe, L. [National Institute for Physics and Nuclear Engineering, Magurele (Romania); Hoff, P. [Department of Chemistry, University of Oslo, Oslo (Norway); Koester, U. [Institut Laue Langevin, 6 Rue Jules Horowitz, F-38042 Grenoble Cedex 9 (France); and others

2013-06-10T23:59:59.000Z

485

Growth and optical characterization of multilayers of InGaN quantum dots  

E-Print Network [OSTI]

carried out using a two photon excitation technique employing a picosecond mode-locked Ti-sapphire laser emitting at 790 nm. Samples were mounted in a cold -finger cryostat that could be cooled down to 4.2 K and the laser was focused through a microscope... GaN quantum dots Article Type: Research Paper Section/Category: General subjects Keywords: B2. InGaN quantum dots; A1. Photoluminescence; B1. Nitrides; A3. Metal-organic vapour phase epitaxy Corresponding Author: Dr Tongtong Zhu, Ph...

Zhu, Tontong; El-Ella, Haitham; Reid, Benjamin; Holmes, Mark; Taylor, Robert; Kappers, Menno; Oliver, Rachel

2012-01-01T23:59:59.000Z

486

Temperature-dependent quantum efficiency of Ga(N,As,P) quantum wells  

SciTech Connect (OSTI)

The photoluminescence quantum efficiencies of a series of Ga(N,As,P)/GaP multiple quantum wells are analyzed. The external quantum efficiencies are derived from the absorbed and the emitted light intensities measured using an integrating sphere mounted inside a closed-cycle helium cryostat. By taking into account the device layer sequences as well as internal reflections and reabsorption, the internal quantum efficiencies yield values above 90% for all samples at cryogenic temperatures. The temperature-dependence of the quantum efficiencies as a function of active quantum well layer design reveal the internal interfaces as remaining growth challenge in these heterostructures.

Rosemann, N. W., E-mail: Nils.Rosemann@Physik.Uni-Marburg.de; Metzger, B.; Volz, K.; Chatterjee, S. [Faculty of Physics and Material Sciences Center, Philipps-Universitt Marburg, Renthof 5, D-35032 Marburg (Germany)] [Faculty of Physics and Material Sciences Center, Philipps-Universitt Marburg, Renthof 5, D-35032 Marburg (Germany); Kunert, B. [NAsP III/V GmbH, Am Knechtacker 19, D-35041 Marburg (Germany)] [NAsP III/V GmbH, Am Knechtacker 19, D-35041 Marburg (Germany); Stolz, W. [Faculty of Physics and Material Sciences Center, Philipps-Universitt Marburg, Renthof 5, D-35032 Marburg (Germany) [Faculty of Physics and Material Sciences Center, Philipps-Universitt Marburg, Renthof 5, D-35032 Marburg (Germany); NAsP III/V GmbH, Am Knechtacker 19, D-35041 Marburg (Germany)

2013-12-16T23:59:59.000Z

487

Efficient vertical coupling of photodiodes to InGaAsP rib waveguides  

SciTech Connect (OSTI)

We demonstrate vertical integration of InGaAs mesa photodiodes with InGaAsP rib waveguides employing an intermediate optical impedance matching layer. The diode length necessary for 90% light absorption at 1.52 {mu}m wavelength was 42 {mu}m, a threefold reduction in diode length with respect to previous work employing similar waveguides without a matching layer. The quantum efficiency was observed to be almost independent of the optical wavelength and polarization. The influence of spatial transient intensity redistribution effects on these devices is investigated in detail.

Deri, R.J.; Doldissen, W.; Hawkins, R.J.; Bhat, R.; Soole, J.B.D.; Schiavone, L.M.; Seto, M.; Andreadakis, N.; Silberberg, Y.; Koza, M.A. (Bellcore, 331 Newman Springs Road, Red Bank, New Jersey 07701-7040 (USA))

1991-06-17T23:59:59.000Z

488

Localization of degradation in InP/InGaAsP mushroom stripe lasers  

SciTech Connect (OSTI)

The rapid degradation observed in InP/InGaAsP mushroom stripe lasers covered with phosphosilicate glass (PSG) was investigated by comparing the light-current characteristics as a function of the preparation technique. We were able to show that the PSG-covering layer is not the reason for the rapid degradation. By inspecting the light-current characteristics before and after degradation and by additional underetching the laser structure after degradation we were able to localize the degraded regions on the open side walls of the InGaAsP active layer.

Jung, H.; Marschall, P.

1987-07-13T23:59:59.000Z

489

Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs  

SciTech Connect (OSTI)

We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.

Buckley, Sonia, E-mail: bucklesm@stanford.edu; Radulaski, Marina; Vu?kovi?, Jelena [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States)] [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States); Biermann, Klaus [Paul-Drude-Institut fr Festkrperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)] [Paul-Drude-Institut fr Festkrperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

2013-11-18T23:59:59.000Z

490

An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode  

SciTech Connect (OSTI)

We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski-Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.

Mehta, M.; Michaelis de Vasconcellos, S.; Zrenner, A.; Meier, C. [Department of Physics and Center for Optoelectronics and Photonics Paderborn (CeOPP), University of Paderborn, Warburger Street 100, 33098 Paderborn (Germany); Reuter, D.; Wieck, A. D. [Applied Solid State Physics, Ruhr-University of Bochum, Universitaetsstr. 150, 44780 Bochum (Germany)

2010-10-04T23:59:59.000Z

491

Biexciton emission from single isoelectronic traps formed by nitrogen-nitrogen pairs in GaAs  

SciTech Connect (OSTI)

We have studied photoluminescence (PL) from individual isoelectronic traps formed by nitrogen-nitrogen (NN) pairs in GaAs. Sharp emission lines due to exciton and biexciton were observed from individual isoelectronic traps in nitrogen atomic-layer doped (ALD) GaAs. The binding energy of biexciton bound to individual isoelectronic traps was approximately 8 meV. Both the exciton and biexciton luminescence lines show completely random polarization and no fine-structure splitting. These results are desirable to the application to the quantum cryptography used in the field of quantum information technology.

Takamiya, Kengo; Fukushima, Toshiyuki; Yagi, Shuhei; Hijikata, Yasuto; Yaguchi, Hiroyuki [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku , Saitama 338-8570 (Japan); Mochizuki, Toshimitsu; Yoshita, Masahiro; Akiyama, Hidefumi [Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Kuboya, Shigeyuki; Onabe, Kentaro [Department of Advanced Materials Science, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Katayama, Ryuji [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2013-12-04T23:59:59.000Z

492

Winter Break 2011 (January) Knowledge is Power Program  

E-Print Network [OSTI]

, TX) Kentucky Equine Humane Center (Nicholsville, Kentucky) Grand Canyon: Kane Ranch (Marble participants) Community Collaborations, Flood Relief (Atlanta, GA) (10 participants) Weekend Breaks Fall 2009, San Juan, TX (10 participants) Weekend