National Library of Energy BETA

Sample records for gaas gypsum plaster

  1. Radiation absorption properties of different plaster samples

    SciTech Connect (OSTI)

    Akkurt, Iskender; Guenoglu, Kadir; Mavi, Betuel; K Latin-Small-Letter-Dotless-I l Latin-Small-Letter-Dotless-I ncarslan, Semsettin; Seven, Aysun

    2012-09-06

    Although the plaster is one of the oldest known synthetic building materials, nowadays, it is used as interior coating of walls and ceilings of buildings. Thus measuring its radiation shielding properties is vital. For this purpose, radiation absorption properties of different plaster samples in this study. The measurements have been performed using gamma spectrometer system which connected to 3'' Multiplication-Sign 3''NaI (TI) detector.

  2. National Gypsum | 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 QA:QA J-E-1 SECTION J APPENDIXsourceII Jump to: navigation, searchsourceEnergyTexas:NGEN8ModelingGypsum Jump to:

  3. Flue gas desulfurization gypsum and fly ash

    SciTech Connect (OSTI)

    Not Available

    1992-05-01

    The Cumberland Fossil Plant (CUF) is located in Stewart County, Tennessee, and began commercial operation in 1972. This is the Tennessee Valley Authority`s newest fossil (coal-burning) steam electric generating plant. Under current operating conditions, the plant burns approximately seven million tons of coal annually. By-products from the combustion of coal are fly ash, approximately 428,000 tons annually, and bottom ash, approximately 115,000 tons annually. Based on historical load and projected ash production rates, a study was initially undertaken to identify feasible alternatives for marketing, utilization and disposal of ash by-products. The preferred alternative to ensure that facilities are planned for all by-products which will potentially be generated at CUF is to plan facilities to handle wet FGD gypsum and dry fly ash. A number of different sites were evaluated for their suitability for development as FGD gypsum and ash storage facilities. LAW Engineering was contracted to conduct onsite explorations of sites to develop information on the general mature of subsurface soil, rock and groundwater conditions in the site areas. Surveys were also conducted on each site to assess the presence of endangered and threatened species, wetlands and floodplains, archaeological and cultural resources, prime farmland and other site characteristics which must be considered from an environmental perspective.

  4. Crack coalescence in molded gypsum and Carrara marble

    E-Print Network [OSTI]

    Wong, Ngai Yuen

    2008-01-01

    This thesis investigates the fracturing and coalescence behavior in prismatic laboratory molded gypsum and Carrara marble specimens, which consist of either one or two preexisting open flaws, under uniaxial compression. ...

  5. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production

    SciTech Connect (OSTI)

    Jessica Marshall Sanderson

    2006-06-01

    This report presents and discusses results from Task 5 of the study ''Fate of Mercury in Synthetic Gypsum Used for Wallboard Production,'' performed at a full-scale commercial wallboard plant. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. The FGD process is used to control the sulfur dioxide emissions which would result in acid rain if not controlled. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies developed for power plants involve the capture of mercury in FGD systems. The objective of this study is to determine whether any mercury is released into the atmosphere when the synthetic gypsum material is used as a feedstock for wallboard production. The project is being co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope includes five discrete tasks, each conducted at various USG wallboard plants using synthetic gypsum from different FGD systems. The five tasks were to include (1) a baseline test, then variations representing differing power plant (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5, which was to evaluate gypsum produced from an alternate FGD reagent, could not be conducted as planned. Instead, Task 5 was conducted at conditions similar to a previous task, Task 3, although with gypsum from an alternate FGD system. In this project, process stacks in the wallboard plant have been sampled using the Ontario Hydro method. The stack locations sampled for each task include a dryer for the wet gypsum as it enters the plant and a gypsum calciner. The stack of the dryer for the wet wallboard product was also tested as part of this task, and was tested as part of Tasks 1 and 4. Also at each site, in-stream process samples were collected and analyzed for mercury concentration before and after each significant step in wallboard production. The Ontario Hydro results, process sample mercury concentration data, and process data were used to construct mercury mass balances across the wallboard plants. Task 5 was conducted at a wallboard plant processing synthetic gypsum from a power plant that fires Eastern bituminous coal. The power plant is equipped with a selective catalytic reduction (SCR) system for NOX emissions control, but the SCR was bypassed during the time period the gypsum tested was produced. The power plant has a single-loop, open spray tower, limestone reagent FGD system, with forced oxidation conducted in a reaction tank integral with the FGD absorber. The FGD system has gypsum fines blow down as part of the dewatering step. Gypsum fines blow down is believed to be an important variable that impacts the amount of mercury in the gypsum byproduct and possibly its stability during the wallboard process. The results of the Task 5 stack testing, as measured by the Ontario Hydro method, detected that an average of 51% of the incoming mercury in the FGD gypsum was emitted during wallboard production. These losses were distributed as 2% or less each across the wet gypsum dryer and product wallboard dryer, and about 50% across the gypsum calciner. Emissions were similar to what Task 3 results showed, on both a percentage and a mass basis, for gypsum produced by a power plant firing bituminous coal and also having gypsum fines blow down as part of the FGD dewatering scheme. As was seen in the Task 1 through 4 results, most of the mercury detected in the stack testing on the wet gypsum dryer and kettle calciner was in the form of elemental mercury. In the wallboard dryer kiln, a more signific

  6. Analysis of cubic and orthorhombic C3A hydration in presence of gypsum and lime

    E-Print Network [OSTI]

    Kirchheim, A. P.; Fernàndez-Altable, V.; Monteiro, P. J.; Dal Molin, D. C.; Casanova, I.

    2009-01-01

    orthorhombic C 3 A paste with no lime; no monosulfoaluminatein presence of gypsum and lime A. P. Kirchheim Æ V. Fernacubic C 3 A ? gypsum ? 10% lime ? H 2 O mixture, at 7 and 14

  7. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production

    SciTech Connect (OSTI)

    Jessica Sanderson

    2007-12-31

    This report presents and discusses results from the project 'Fate of Mercury in Synthetic Gypsum Used for Wallboard Production', performed at five different full-scale commercial wallboard plants. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies involve the capture of mercury in FGD systems. The objective of this study has been to determine whether any mercury is released into the atmosphere at wallboard manufacturing plants when the synthetic gypsum material is used as a feedstock for wallboard production. The project has been co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope included seven discrete tasks, each including a test conducted at various USG wallboard plants using synthetic gypsum from different wet FGD systems. The project was originally composed of five tasks, which were to include (1) a base-case test, then variations representing differing power plant: (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5,could not be conducted as planned and instead was conducted at conditions similar to Task 3. Subsequently an opportunity arose to test gypsum produced from the Task 5 FGD system, but with an additive expected to impact the stability of mercury, so Task 6 was added to the project. Finally, Task 7 was added to evaluate synthetic gypsum produced at a power plant from an additional coal type. In the project, process stacks in the wallboard plant were sampled using the Ontario Hydro method. In every task, the stack locations sampled included a gypsum dryer and a gypsum calciner. In Tasks 1 and 4 through 7, the stack of the dryer for the wet wallboard product was also tested. Also at each site, in-stream process samples were collected and analyzed for mercury concentration before and after each significant step in wallboard production. These results and process data were used to construct mercury mass balances across the wallboard plants. The results from the project showed a wide range of percentage mercury losses from the synthetic gypsum feedstocks as measured by the Ontario Hydro method at the process stacks, ranging from 2% to 55% of the mercury in the gypsum feedstock. For the tasks exceeding 10% mercury loss across the wallboard plant, most of the loss occurred across the gypsum calciner. When total wallboard emissions remained below 10%, the primary emission location varied with a much less pronounced difference in emission between the gypsum dryer, calciner and board dryer. For all seven tasks, the majority of the mercury emissions were measured to be in the elemental form (Hg{sup 0}). Overall, the measured mercury loss mass rates ranged from 0.01 to 0.17 grams of mercury per dry ton of synthetic gypsum processed, or 0.01 to 0.4 pounds of mercury released per million square feet of wallboard produced from synthetic gypsum. The Coal Combustion Product Production and Use Survey from the American Coal Ash Association (ACAA) indicate that 7,579,187 short tons of synthetic gypsum were used for wallboard production in 2006. Extrapolating the results of this study to the ACAA industry usage rate, we estimate that mercury releases from wallboard production plants in 2006 ranged between 150 to 3000 pounds for the entire U.S. wallboard industry. With only seven sets of wallboard plant measurements, it is difficult to draw firm conclusions about what variables impact the mercury loss percentages across the wallboard plants. One significant o

  8. GaAs MOEMS Technology

    SciTech Connect (OSTI)

    SPAHN, OLGA B.; GROSSETETE, GRANT D.; CICH, MICHAEL J.; TIGGES, CHRIS P.; RENO, JOHN L.; PEAKE, GREGORY M.; KLEM, JOHN F.; LEAN, JEN; FULLER, CHARLES T.; BURKHART, JEFF; BAUER, THOMAS; SULLIVAN, CHARLES T.

    2003-03-01

    Many MEMS-based components require optical monitoring techniques using optoelectronic devices for converting mechanical position information into useful electronic signals. While the constituent piece-parts of such hybrid opto-MEMS components can be separately optimized, the resulting component performance, size, ruggedness and cost are substantially compromised due to assembly and packaging limitations. GaAs MOEMS offers the possibility of monolithically integrating high-performance optoelectronics with simple mechanical structures built in very low-stress epitaxial layers with a resulting component performance determined only by GaAs microfabrication technology limitations. GaAs MOEMS implicitly integrates the capability for radiation-hardened optical communications into the MEMS sensor or actuator component, a vital step towards rugged integrated autonomous microsystems that sense, act, and communicate. This project establishes a new foundational technology that monolithically combines GaAs optoelectronics with simple mechanics. Critical process issues addressed include selectivity, electrochemical characteristics, and anisotropy of the release chemistry, and post-release drying and coating processes. Several types of devices incorporating this novel technology are demonstrated.

  9. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production

    SciTech Connect (OSTI)

    Jessica Sanderson; Gary M. Blythe; Mandi Richardson

    2006-12-01

    This report presents and discusses results from Task 6 of the study 'Fate of Mercury in Synthetic Gypsum Used for Wallboard Production,' performed at a full-scale commercial wallboard plant. Synthetic gypsum produced by wet flue gas desulfurization (FGD) systems on coal-fired power plants is commonly used in the manufacture of wallboard. This practice has long benefited the environment by recycling the FGD gypsum byproduct, which is becoming available in increasing quantities, decreasing the need to landfill this material, and increasing the sustainable design of the wallboard product. However, new concerns have arisen as recent mercury control strategies involve the capture of mercury in FGD systems. The objective of this study is to determine whether any mercury is released into the atmosphere when the synthetic gypsum material is used as a feedstock for wallboard production. The project is being co-funded by the U.S. DOE National Energy Technology Laboratory (Cooperative Agreement DE-FC26-04NT42080), USG Corporation, and EPRI. USG Corporation is the prime contractor, and URS Group is a subcontractor. The project scope now includes six discrete tasks, each conducted at various USG wallboard plants using synthetic gypsum from different FGD systems. The project was originally composed of five tasks, which were to include (1) a baseline test, then variations representing differing power plant: (2) emissions control configurations, (3) treatment of fine gypsum particles, (4) coal types, and (5) FGD reagent types. However, Task 5, which was to include testing with an alternate FGD reagent, could not be conducted as planned. Instead, Task 5 was conducted at conditions similar to Task 3, although with gypsum from an alternate FGD system. Subsequent to conducting Task 5 under these revised conditions, an opportunity arose to test gypsum produced at the same FGD system, but with an additive (Degussa Corporation's TMT-15) being used in the FGD system. TMT-15 was expected to impact the stability of mercury in synthetic gypsum used to produce wallboard, so Task 6 was added to the project to test this theory. In this project, process stacks in the wallboard plant have been sampled using the Ontario Hydro method. For every task, the stack locations sampled have included a dryer for the wet gypsum as it enters the plant and a gypsum calciner. For Tasks 1, 4, 5 and 6, the stack of the dryer for the wet wallboard product was also tested. Also at each site, in-stream process samples were collected and analyzed for mercury concentration before and after each significant step in wallboard production. The Ontario Hydro results, process sample mercury concentration data, and process data were used to construct mercury mass balances across the wallboard plants. Task 6 was conducted at a wallboard plant processing synthetic gypsum from a power plant that fires Eastern bituminous coal. The power plant has a single-loop, open spray tower limestone forced oxidation FGD system, with the forced oxidation conducted in the reaction tank integral with the FGD absorber. The FGD system has gypsum fines blow down as part of the dewatering step. The power plant is equipped with a selective catalytic reduction (SCR) system for NOX emissions control, and the SCR was in service during the time period the gypsum tested was produced. Also, as mentioned above, Degussa additive TMT-15 was being added to the FGD system when this gypsum was produced. The results of the Task 6 stack testing, as measured by the Ontario Hydro method, detected that an average of 55% of the incoming mercury was emitted during wallboard production. These losses were distributed as about 4% across the dryer mill, 6% across the board dryer kiln, and 45% across the kettle calciner. Emissions were similar to what Task 5 results showed on a percentage basis, but about 30% lower on a mass basis. The same power plant FGD system produced the synthetic gypsum used in Task 5 (with no use of TMT-15) and in Task 6 (with TMT-15 added to the FGD system). The lower emissions on a mass basis appeared

  10. Recovery of chemical values from waste gypsum. Final report, December 1989-August 1992

    SciTech Connect (OSTI)

    Paisley, M.A.; Litt, R.D.

    1992-10-15

    A two-stage, two reactor process is being developed to recover sulfur or sulfuric acid and lime from waste gypsum. Waste gypsum is produced by a variety of industries including chemical, fertilizer and electric utilities. Current environmental regulations are increasing the landfill disposal cost to $30/ton or more depending on specific local conditions. These costs are expected to increase and the quantity of waste gypsum is also expected to increase. The two-stage gypsum recovery process uses two separate fluidized bed reactors to (1) reduce the gypsum to calcium sulfide (CaS) and then (2) roast the sulfide with air producing a SO2-rich gas and regenerated CaO. Fluidization and elutriation problems in the first stage were overcome to achieve up to 85 percent conversion of gypsum to CaS. Reducing gas composition, temperature, and solids residence time were shown to be the primary parameters affecting the reactions. Additional work is needed to achieve even greater conversion and to demonstrate the integrated 2-stage operation. A preliminary economic evaluation indicated a 3-year payback could be achieved for a 1000 ton/day plant. The capital cost was estimated to be $8.5 million. Operating cost savings were based on reduced disposal cost, use/sale of sulfuric acid and use/sale of lime.

  11. Socio-economic and Environmental Impact Analysis of Khothagpa Gypsum Mine

    E-Print Network [OSTI]

    Galay, Karma

    2008-01-01

    of Khothagpa and Pemagatshel; gup of Shumar gewog; truckers; Chief Executive Officer and some employees (both permanent and temporary) of the corporation as well as the on- site observations of the author of this paper. Part 3: Economic impacts A. Positive... in the nearby areas. Dust is generated by blasting, loading and haulage, vehicular movements, open air disposal of waste rocks, drilling, and crushing. These fugitive dusts from mine site as well as from the factory of Druk Plaster and Chemicals Limited...

  12. Gypsum (CaSO4 .2H2O) and anhydrite (CaSO4) are two related minerals that formed

    E-Print Network [OSTI]

    Polly, David

    called satin spar. Although associated with gypsum, anhydrite lacks H2O molecules. Anhydrite closely Indiana's Evaporite Minerals satin spar gypsum #12;611 North Walnut Grove Ave. Bloomington, Indiana 47405

  13. Manufacture of ammonium sulfate fertilizer from FGD-gypsum. Technical report, March 1--May 31, 1995

    SciTech Connect (OSTI)

    Chou, M.I.M.; Rostam-Abadi, Ml; Lytle, J.M.; Bruinius, J.A.; Li, Y.C. [Illinois State Geological Survey, Urbana, IL (United States); Hoeft, R. [Illinois Univ., Urbana, IL (United States); Dewey, S. [AlliedSignal-Chemicals (United States); Achorn, F. [Southeast Marketing Chem. Process INc. (SE-ME) (United States)

    1995-12-31

    Goal is to assess technical and economic feasibility for producing fertilizer-grade ammonium sulfate from gypsum produced in limestone flue gas desulfurization (FGD). This is the 1st year of a 2-year program among Illinois State Geological Survey, University of Illinois (Urbana-Champaign), Allied-Signal, Marketing Chem. Process Inc., Henry Fertilizer, Illinois Power Co., and Central Illinois Public Services. In previous quarter, chemistry and process conditions were reviewed and a reactor system set up and used to conduct laboratory tests. FGD-gypsum from Abbott power plant was used. The scrubber, a Chiyoda Thoroughbred 121 FGD, produced a filter cake (98.36% gypsum and < 0.01% CaSO{sub 3}). Conversion of FGD- gypsum to ammonium sulfate was tested at 60-70{degree}C for 5-6 hr. Yield up to 82% and purity up to 95% were achieved for the ammonium sulfate production. During this quarter, more bench-scale experiments including a mass balance analysis were conducted; a yield up to 83% and up to 99% purity were achieved. A literature survey was completed and a preliminary process flow sheet was developed. Economics of the process is being estimated.

  14. Gypsum treated fly ash as a liner for waste disposal facilities

    SciTech Connect (OSTI)

    Sivapullaiah, Puvvadi V.; Baig, M. Arif Ali

    2011-02-15

    Fly ash has potential application in the construction of base liners for waste containment facilities. While most of the fly ashes improve in the strength with curing, the ranges of permeabilities they attain may often not meet the basic requirement of a liner material. An attempt has been made in the present context to reduce the hydraulic conductivity by adding lime content up to 10% to two selected samples of class F fly ashes. The use of gypsum, which is known to accelerate the unconfined compressive strength by increasing the lime reactivity, has been investigated in further improving the hydraulic conductivity. Hydraulic conductivities of the compacted specimens have been determined in the laboratory using the falling head method. It has been observed that the addition of gypsum reduces the hydraulic conductivity of the lime treated fly ashes. The reduction in the hydraulic conductivity of the samples containing gypsum is significantly more for samples with high amounts of lime contents (as high as 1000 times) than those fly ashes with lower amounts of lime. However there is a relatively more increase in the strengths of the samples with the inclusion of gypsum to the fly ashes at lower lime contents. This is due to the fact that excess lime added to fly ash is not effectively converted into pozzolanic compounds. Even the presence of gypsum is observed not to activate these reactions with excess lime. On the other hand the higher amount of lime in the presence of sulphate is observed to produce more cementitious compounds which block the pores in the fly ash. The consequent reduction in the hydraulic conductivity of fly ash would be beneficial in reducing the leachability of trace elements present in the fly ash when used as a base liner.

  15. Au impact on GaAs epitaxial growth on GaAs (111){sub B} substrates in molecular beam epitaxy

    SciTech Connect (OSTI)

    Liao, Zhi-Ming; Chen, Zhi-Gang; Xu, Hong-Yi; Guo, Ya-Nan; Sun, Wen; Zhang, Zhi; Yang, Lei; Lu, Zhen-Yu; Chen, Ping-Ping; Lu, Wei; Zou, Jin; Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, Queensland 4072

    2013-02-11

    GaAs growth behaviour under the presence of Au nanoparticles on GaAs {l_brace}111{r_brace}{sub B} substrate is investigated using electron microscopy. It has been found that, during annealing, enhanced Ga surface diffusion towards Au nanoparticles leads to the GaAs epitaxial growth into {l_brace}113{r_brace}{sub B} faceted triangular pyramids under Au nanoparticles, governed by the thermodynamic growth, while during conventional GaAs growth, growth kinetics dominates, resulting in the flatted triangular pyramids at high temperature and the epitaxial nanowires growth at relatively low temperature. This study provides an insight of Au nanoparticle impact on GaAs growth, which is critical for understanding the formation mechanisms of semiconductor nanowires.

  16. Photoeffects in WO{sub 3}/GaAs electrode

    SciTech Connect (OSTI)

    Yoon, K.H.; Lee, J.W.; Cho, Y.S.; Kang, D.H.

    1996-12-01

    Photoeffects of a {ital p}-type GaAs coated with WO{sub 3} thin film have been investigated as a function of film thickness and photoresponse transients of the WO{sub 3}/GaAs electrode were studied. Also, these results were compared to those for a single {ital p}-type GaAs electrode. The photocurrent of the WO{sub 3}/GaAs electrode depended on the film thickness of the WO{sub 3}, showing an optimum photon efficiency for specimens of 800 A thickness. This is due to the existence of an effective interface state within the band gap which reduces trapping of carriers and facilitates carrier movement. For an 800-A-thick WO{sub 3} thin film deposited {ital p}-GaAs photoelectrode, the photogenerated electrons were found to move to an electrolyte at a higher positive onset potential compared with that of single {ital p}-type GaAs, which was confirmed as a result of transient behavior. {ital I}{endash}{ital V} and {ital C}{endash}{ital V} characteristics of the WO{sub 3}/GaAs electrode were also compared with those of a single {ital p}-type GaAs electrode. {copyright} {ital 1996 American Institute of Physics.}

  17. Localized corrosion of GaAs surfaces and formation of porous GaAs

    SciTech Connect (OSTI)

    Schmuki, P.; Vitus, C.M.; Isaacs, H.S.; Fraser, J.; Graham, M.J.

    1995-12-01

    The present work deals with pitting corrosion of p- and n-type GaAs (100). Pit growth can be electrochemically initiated on both conduction types in chloride-containing solutions and leads after extended periods of time to the formation of a porous GaAs structure. In the case of p-type material, localized corrosion is only observed if a passivating film is present on the surface, otherwise -- e.g. in acidic solutions -- the material suffers from a uniform attack (electropolishing) which is independent of the anion present. In contrast, pitting corrosion of n-type material can be triggered independent of the presence of an oxide film. This is explained in terms of the different current limiting factor for the differently doped materials (oxide film in the case of the p- and a space charge layer in the case of the n-GaAs). The porous structure was characterized by SEM, EDX and AES, and consists mainly of GaAs. From scratch experiments it is clear that the pit initiation process is strongly influenced by surface defects. For n-type material, AFM investigations show that light induced roughening of the order of several hundred nm occurs under non-passivating conditions. This nm- scale roughening however does not affect the pitting process.

  18. Holographic interferometry study of the dissolution and diffusion of gypsum in water

    E-Print Network [OSTI]

    Colombani, Jean; 10.1016/j.gca.2007.01.012

    2009-01-01

    We have performed holographic interferometry measurements of the dissolution of the (010) plane of a cleaved gypsum single crystal in pure water. These experiments have provided the value of the dissolution rate constant k of gypsum in water and the value of the interdiffusion coefficient D of its aqueous species in water. D is 1.0 x 10^-9 m2 s^-1, a value close to the theoretical value generally used in dissolution studies. k is 4 x 10^-5 mol m^-2 s^-1. It directly characterizes the microscopic transfer rate at the solid-liquid interface, and is not an averaged value deduced from quantities measured far from the surface as in macroscopic dissolution experiments. It is found to be two times lower than the value obtained from macroscopic experiments.

  19. Modeling the VOC emissions from interior latex paint applied to gypsum board

    SciTech Connect (OSTI)

    Guo, Z.; Fortmann, R.; Marfiak, S.; Tichenor, B.; Sparks, L.

    1997-09-01

    The paper discusses modeling volatile organic compound (VOC) emissions from indoor latex paint applied to gypsum board. An empirical source model for a porous substrate was developed that takes both the wet- and dry-stage emission into consideration. Tests in the U.S. EPA`s Source Characterization Laboratory showed that common interior surfaces such as gypsum board and carpet could absorb significant amounts of latex paint VOCS from the air, and that they were re-emitted very slowly. An indoor air quality model incorporating the source model, an irreversible sink model, and the air movement data obtained from tracer gas tests made satisfactory predictions for the VOC levels in a test house.

  20. Electrical degradation mechanisms of RF power GaAs PHEMTs

    E-Print Network [OSTI]

    Villanueva, Anita A. (Anita Ariel), 1978-

    2007-01-01

    GaAs Pseudomorphic High-Electron Mobility Transistors (PHEMTs) are widely used in RF power applications. Since these devices typically operate at high power levels and under high voltage biasing, their electrical reliability ...

  1. Accurate characterization and improvement of GaAs microstrip attenuation 

    E-Print Network [OSTI]

    Carroll, James Mason

    1992-01-01

    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...

  2. Nonlinear Terahertz Metamaterials via Field-Enhanced Carrier Dynamics in GaAs

    E-Print Network [OSTI]

    Fan, Kebin

    We demonstrate nonlinear metamaterial split ring resonators (SRRs) on GaAs at terahertz frequencies. For SRRs on doped GaAs films, incident terahertz radiation with peak fields of ?20–160??kV/cm drives intervalley scattering. ...

  3. 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

  4. Near perfect solar absorption in ultra-thin-film GaAs photonic crystals

    E-Print Network [OSTI]

    John, Sajeev

    Near perfect solar absorption in ultra-thin-film GaAs photonic crystals Sergey Eyderman,*a Alexei voltage of GaAs solar cells. The current world record for high efficiency solar cells is held by thin ultra-thin (GaAs in low-cost solar cells. However, this reduction in the volume

  5. ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission

    E-Print Network [OSTI]

    Polman, Albert

    a non-concentrating system with limited emission angle in a thin, light trapping GaAs solar cellORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission angle Emily D Kosten1 of a high-quality GaAs solar cell is a feasible route to achieving power conversion efficiencies above 38

  6. Polycrystalline MBE-grown GaAs for solar cells

    SciTech Connect (OSTI)

    Friedman, D.J.; Kurtz, S.R.; Kibbler, A.E.; Al-Jassim, M.; Jones, K.; Keyes, B.; Matson, R.

    1997-02-01

    This paper will discuss initial studies of thin-film GaAs grown by molecular-beam epitaxy for use in developing a thin-film GaAs solar cell. Photocurrent and photoluminescence intensity are related to the material morphology as a function of growth conditions. Growth temperature and V/III ratio have a dramatic effect on the photocurrent. However, it seems likely that even after optimizing such growth parameters, it will be necessary to provide substrates that can provide templates to enhance grain size from the start of thin-film growth. {copyright} {ital 1997 American Institute of Physics.}

  7. Polycrystalline MBE-grown GaAs for solar cells

    SciTech Connect (OSTI)

    Friedman, D. J.; Kurtz, Sarah R.; Kibbler, A. E.; Al-Jassim, M.; Jones, K.; Keyes, B.; Matson, R.

    1997-02-15

    This paper will discuss initial studies of thin-film GaAs grown by molecular-beam epitaxy for use in developing a thin-film GaAs solar cell. Photocurrent and photoluminescence intensity are related to the material morphology as a function of growth conditions. Growth temperature and V/III ratio have a dramatic effect on the photocurrent. However, it seems likely that even after optimizing such growth parameters, it will be necessary to provide substrates that can provide templates to enhance grain size from the start of thin-film growth.

  8. Coupled measurements of ?^18O and ?D of hydration water and salinity of fluid inclusions in gypsum from the Messinian Yesares Member, Sorbas Basin (SE Spain)

    E-Print Network [OSTI]

    Evans, Nicholas P.; Turchyn, Alexandra V.; Gázquez, Fernando; Bontognali, Tomaso R. R.; Chapman, Hazel J.; Hodell, David A.

    2015-01-01

    . The ?1818O and ?D of gypsum hydration water (CaSO4•2H2O) and salinity of fluid inclusions were measured in the same samples to test if they record the composition of the mother fluid from which gypsum was precipitated. Water isotopes are highly...

  9. High-quality InP on GaAs

    E-Print Network [OSTI]

    Quitoriano, Nathaniel Joseph

    2006-01-01

    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, ...

  10. Nanoscale GaAs metalsemiconductormetal photodetectors fabricated using nanoimprint lithography

    E-Print Network [OSTI]

    ­V) characteristics of the contacts are very sensi- tive to the surface states and defects. In this letter, we report mold with interdigited fin- gers was first created on a silicon substrate. Next, a layer of polymethylmethancrylate PMMA was spun on a semi- insulating SI GaAs substrate. Before imprinting, both the mold

  11. Behavior of Aluminum, Arsenic, and Vanadium during the Neutralization of Red Mud Leachate by HCl, Gypsum, or Seawater

    E-Print Network [OSTI]

    Burke, Ian

    Behavior of Aluminum, Arsenic, and Vanadium during the Neutralization of Red Mud Leachate by HCl ABSTRACT: Red mud leachate (pH 13) collected from Ajka, Hungary is neutralized to via surface adsorption of As onto the Al oxyhydroxides. Gypsum addition to red mud leachate results

  12. Radiation damage of GaAs thin-film solar cells on Si substrates

    SciTech Connect (OSTI)

    Itoh, Y.; Yamaguchi, M.; Nishioka, T.; Yamamoto, A.

    1987-01-15

    1-MeV electron irradiation damages in GaAs thin-film solar cells on Si substrates are examined for the first time. Damage constant for minority-carrier diffusion length in GaAs heteroepitaxial films on Si substrates is found to be the same as that in GaAs homoepitaxial films on GaAs substrates. This agreement suggests that GaAs/Si has the same defect introduction rate with radiation as GaAs/GaAs. The degradation of GaAs solar cells on Si with electron irradiation is less than that of GaAs solar cells on GaAs, because in the present, GaAs films on Si substrates have lower minority-carrier diffusion length compared to GaAs films on GaAs and these films are insensitive to radiation. The p/sup +/-p/sup +/-n AlGaAs-GaAs heteroface solar cell with junction depth of about 0.3 ..mu..m is concluded to be useful for a high-efficiency and radiation-resistant solar cell fabricated on a Si substrate.

  13. Testing a GaAs cathode in SRF gun

    SciTech Connect (OSTI)

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

    2011-03-28

    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.

  14. Formation and properties of porous GaAs

    SciTech Connect (OSTI)

    Schmuki, P.; Lockwood, D.J.; Fraser, J.W.; Graham, M.J.; Isaacs, H.S.

    1996-06-01

    Porous structures on n-type GaAs (100) can be grown electrochemically in chloride-containing solutions. Crystallographic etching of the sample is a precursor stage of the attack. Polarization curves reveal the existanece of a critical onset potential for por formation (PFP). PFP is strongly dependent on the doping level of the sample and presence of surface defects. Good agreement between PFP and breakdown voltage of the space charge layer is found. Surface analysis by EDX, AES, and XPS show that the porous structure consists mainly of GaAs and that anion uptake in the structure can only observed after attackhas been initiated. Photoluminescence measurements reveal (under certain conditions) visible light emission from the porous structure.

  15. Minority-carrier properties of GaAs on silicon

    SciTech Connect (OSTI)

    Ahrenkiel, R.K.; Al-Jassim, M.M.; Dunlavy, D.J.; Jones, K.M.; Vernon, S.M.; Tobin, S.P.; Haven, V.E.

    1988-07-18

    The minority-carrier lifetimes of the heteroepitaxial system of GaAs on Si are limited by recombination at mismatch dislocations. Here we show that increasing the thickness of the buffer layer, with an additional annealing step, reduces the dislocation density by about an order of magnitude. At the same time, the minority-carrier lifetime in these double heterostructures increases more than an order of magnitude.

  16. GEOMORPHOLOGICAL EVIDENCE OF PLAUSIBLE WATER ACTIVITY AND EVAPORITIC DEPOSITION IN INTERDUNE AREAS OF THE GYPSUM-RICH OLYMPIA UNDAE DUNE FIELD. A.

    E-Print Network [OSTI]

    Bourke, Mary C.

    OF THE GYPSUM-RICH OLYMPIA UNDAE DUNE FIELD. A. Szynkiewicz1 , R.C. Ewing2 , K.E. Fishbaugh3 , M.C. Bourke4 , D, P.O. Box 1086, Holloman Air Force Base, NM 88330. Introduction: The Olympia Undae Dune Field. Although the dune sand is likely to be mainly com- posed of pyroxene-bearing sand, in some areas the gypsum

  17. A study of microstrip T-juction discontinuity effects and modeling on GAAS substrates 

    E-Print Network [OSTI]

    Guill, Dennis Jarrett

    1999-01-01

    . Currently, GaAs T-junction discontinuity effects and circuit models are not fully understood nor accurate. This thesis thoroughly characterizes 100 um thick GaAs based microstrip T-junction discontinuity effects. This thesis also provides a new CAD based...

  18. Hetero-epitaxy of perovskite oxides on GaAs(001) by molecular beam epitaxy

    SciTech Connect (OSTI)

    Liang, Y.; Kulik, J.; Eschrich, T.C.; Droopad, R.; Yu, Z.; Maniar, P. [Microelectronics and Physical Sciences Laboratory, Process and Materials Characterization Laboratory, and Microelectronics and Physical Sciences Laboratory, Motorola Inc., 2100 East Elliot Road, Tempe, Arizona 85284 (United States)

    2004-08-16

    Hetero-epitaxy of single-crystal perovskite SrTiO{sub 3} on GaAs(001) was achieved using molecular beam epitaxy. The growth was accomplished by deposition of a submonolayer of titanium on GaAs(001), followed by the co-deposition of strontium and titanium initiated at a low-temperature, low-oxygen-pressure condition. X-ray photoelectron spectroscopy showed that the Ti prelayer reacted with As and formed TiAs-like species on the As terminated GaAs(001) surface. Reflection-high-energy-electron diffraction showed that SrTiO{sub 3} grew coherently on the GaAs(001) at early stage of growth. This coherent behavior began to degrade when SrTiO{sub 3} thickness exceeded 20 A ring . Cross-sectional transmission electron microscopy revealed an abrupt interface between SrTiO{sub 3} and GaAs and good crystallinity of the SrTiO{sub 3} film. An epitaxial relationship between SrTiO{sub 3} and GaAs was further confirmed by x-ray diffraction. The success of growth of SrTiO{sub 3} on GaAs paves the way for integration of various functional perovskite oxides with GaAs.

  19. Radiation studies for GaAs in the ATLAS Inner Detector

    E-Print Network [OSTI]

    M. Rogalla; Th. Eich; N. Evans; R. Geppert; R. Goeppert; R. Irsigler; J. Ludwig; K. Runge; Th. Schmid

    1997-01-22

    We estimate the hardness factors and the equivalent 1 MeV neutron fluences for hadrons fluences expected at the GaAs positions wheels in the ATLAS Inner Detector. On this basis the degradation of the GaAs particle detectors made from different substrates as a function of years LHC operation is predicted.

  20. Data Protection Statement The GAA Oral History Project aims to record the fullest possible picture of

    E-Print Network [OSTI]

    Huang, Jianyu

    , dissertation or similar research. · Publication worldwide on the internet. The entire GAA Oral History ProjectData Protection Statement The GAA Oral History Project aims to record the fullest possible picture History Project is requesting that people fill out one of the questionnaires or send the project a letter

  1. Polycrystalline GaAs solar cells on low-cost Silicon-Film{trademark} substrates

    SciTech Connect (OSTI)

    Mauk, M.G.; Feyock, B.W.; Hall, R.B.; Cavanaugh, K.D.; Cotter, J.E.

    1997-12-31

    The authors assess the potential of a low-cost, large-area Silicon-Film{trademark} sheet as a substrate for thin-film polycrystalline GaAs solar cells. Silicon-Film is a relatively inexpensive material on which large-grain (>2 mm) polycrystalline GaAs films can be formed. The GaAs epitaxial layers are grown by a simple close-spaced vapor transport (CSVT) technique using water vapor as a transport agent. A recrystallized Ge{sub 1{minus}x}Si{sub x} buffer layer between the GaAs epilayer and Silicon-Film substrate can facilitate growth of the GaAs. Selective epitaxy on patterned, oxide-masked substrates is effective in reducing thermal stress effects.

  2. Coal fly ash and phospho-gypsum mixture as an amendment to improve rice paddy soil fertility

    SciTech Connect (OSTI)

    Lee, Y.B.; Ha, H.S.; Lee, C.H.; Kim, P.J.

    2008-04-15

    Rice is a plant that requires high levels of silica (Si). As a silicate NOD source to rice, coal fly ash (hereafter, fly ash), which has an alkaline pH and high available silicate and boron (B) contents, was mixed with phosphor-gypsum (hereafter, gypsum, 50%, wt wt{sup -1}), a by-product from the production of phosphate fertilizer, to improve the fly ash limitation. Field experiments were carried out to evaluate the effect of the mixture on soil properties and rice (Oryza sativa) productivity in silt loam (SiL) and loamy sand (LS) soils to which 0 (FG 0), 20 (FG 20), 40 (FG 40), and 60 (FG 60) Mg ha{sup -1} were added. The mixture increased the amount of available silicate and exchangeable calcium (Ca) contents in the soils and the uptake of silicate by rice plant. The mixture did not result in accumulation of heavy metals in soil and an excessive uptake of heavy metals by the rice grain. The available boron content in soil increased with the mixture application levels up to 1.42 mg kg{sup -1} following the application of 60 Mg ha{sup -1} but did not show toxicity. The mixture increased significantly rice yield and showed the highest yields following the addition of 30-40 Mg ha{sup -1} in two soils. It is concluded that the fly ash and gypsum mixture could be a good source of inorganic soil amendments to restore the soil nutrient balance in rice paddy soil.

  3. Development of metallization for GaAs and AlGaAs concentrator solar cells

    SciTech Connect (OSTI)

    Tobin, S.P.

    1987-04-01

    A three-layer metallization system was developed for high temperature stability on GaAs and AlGaAs solar cells. The layers are a Pt ohmic contact metal that forms thermally stable compounds with GaAs, a TiN diffusion barrier, and a gold conductor. The solar cell structure was also designed for contact stability, with the key component being a heavily doped GaAs cap layer. Reactively sputtered TiN was found to act as an excellent barrier when deposited under the proper conditions. The conditions were carefully optimized for low resistivity and low stress in the films. A low but nonzero substrate bias during sputtering was found to be important. Solar cells with sputtered metallizations of Pt/TiN/Ti/Pt/Au were found to be thermally stable up to 500/sup 0/C for 15 minutes in vacuum. At 600/sup 0/C there was catastrophic degradation of the cells due to dissociation of uncapped GaAs surfaces. Below this temperature the metallization performed as designed. The Pt and GaAs layers reacted to form a stable PtGa compound layer that gave low contact resistance. There was no penetration of Au or GaAs through the barrier layer. These results are a very encouraging first step leading to stable, reliable GaAs and AlGaAs concentrator cells.

  4. Sulfur-mediated palladium catalyst immobilized on a GaAs surface

    SciTech Connect (OSTI)

    Shimoda, M. [Surface Physics and Structure Unit, Surface Physics Group, National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Konishi, T. [Anan National College of Technology, 265 Aoki, Minobayashi-cho, Anan, Tokushima 774-0017 (Japan); Nishiwaki, N. [School of Environmental and Engineering, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 (Japan); Yamashita, Y.; Yoshikawa, H. [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)

    2012-06-15

    We present a hard x-ray photoelectron spectroscopy study on the preparation process of palladium catalyst immobilized on an S-terminated GaAs(100) surface. It is revealed that Pd(II) species are reduced on the GaAs surface and yield Pd nanoparticles during the process of Pd immobilization and the subsequent heat treatment. A comparison with the results on GaAs without S-termination suggests that the reduction of Pd is promoted by hydroxy groups during the Pd immobilization and by S during the heat treatment.

  5. Terahertz waveguide spectroscopy of two-dimensional plasmons in GaAs

    E-Print Network [OSTI]

    Harris, C. Thomas (Charles Thomas)

    2010-01-01

    The electrical characteristics of high-mobility, two-dimensional electron gas (2DEG) systems, such as GaAs quantum wells, have been well-studied at low frequencies and in extreme conditions of high magnetic fields and ...

  6. Molecular Dynamics Simulation of GaAs Molecular Beam Epitaxy D. A. Murdick,1

    E-Print Network [OSTI]

    Wadley, Haydn

    of Virginia, Charlottesville, Virginia 22904, USA 2 Department of Materials, University of Oxford, Oxford OX1 3PH, UK ABSTRACT The vapor deposition of epitaxial GaAs and (Ga,Mn)As thin films during far-temperature growth of Ga0.94Mn0.06As and the Mn clustering trends in as-grown films. INTRODUCTION GaAs is widely used

  7. Integration of subwavelength optical nanostructures for improved antireflection performance of mechanically flexible GaAs solar cells

    E-Print Network [OSTI]

    Yu, Edward T.

    to produce mechanically flexible, low-cost, light-weight, and high-efficiency GaAs thin-film solar cells of mechanically flexible GaAs solar cells fabricated by epitaxial lift-off Xiaohan Li a,n , Ping-Chun Li a , Li Ji bilayer antireflection coatings, respectively, with epitaxial lift-off single-junction GaAs solar cells

  8. Defect studies in low-temperature-grown GaAs

    SciTech Connect (OSTI)

    Bliss, D.E.

    1992-11-01

    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.

  9. Continued development of metallization for GaAs concentrator cells

    SciTech Connect (OSTI)

    Tobin, S.P.

    1988-11-01

    The objective of this work was the integration of thermally stable metallizations with a high-efficiency GaAs concentrator cell process. For p-GaAs we used a Pt-TiN-Au metallization developed under a previous Sandia Contract. For n-GaAs the best results were obtained for AuGe-TiN-Au. Baseline p/n cells with a CrAu metallization achieved efficiencies of 25.4% at 200 suns. Efficiencies were about 22% at one sun. At one sun, p/n cells with high-temperature contacts were 22.2% efficient, showing that there is no efficiency penalty with the high-temperature metallization. Development efforts on n/p cells yielded high short-circuit currents and open-circuit voltages, with both conventional and high-temperature metallizations. Thermal annealing tests showed that cells with the Pt-TiN-Au metallization were more stable than those with the baseline metallization, withstanding a 15-minute anneal at 500/degree/C with negligible efficiency degradation. 22 refs., 64 figs., 54 tabs.

  10. GaAs Blocked-Impurity-Band Detectors for Far-Infrared Astronomy

    SciTech Connect (OSTI)

    Cardozo, Benjamin Lewin

    2004-12-21

    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.

  11. MOCVD growth of GaAs solar cells on silicon substrates

    SciTech Connect (OSTI)

    Vernon, S.M.; Haven, V.E.; Geoffroy, L.M.; Sanfacon, M.M.; Mastrovito, A.L. )

    1992-12-01

    This paper reports advances in the development of solar cells made from GaAs-on-Si structures prepared by metalorganic chemical vapor deposition (MOCVD). The use of concentrator cells, operating at [similar to]200 suns, has led to the efficiency achievements of 21.3% (AM1.5D) for a GaAs-on-Si solar cell, and 27.6 (AM1.5D) for a homoepitaxial GaAs cell. The development of epitaxial multilayer dielectric mirrors (Bragg reflectors), as back-surface reflectors in thin-film GaAs cells, on both Si and GaAs substrates, is shown to lead to modest efficiency increases, over that of conventional designs.

  12. Numerical analysis for high-efficiency GaAs solar cells fabricated on Si substrates

    SciTech Connect (OSTI)

    Yamaguchi, M.; Amano, C.; Itoh, Y.

    1989-07-15

    This paper describes some recent developments in GaAs thin-film solar cells fabricated on Si substrates by metalorganic chemical vapor deposition and numerically analyzes them.GaAs solar cells with efficiency of more than 18% are successfully fabricated on Si substrates by reducing the dislocation density. Photovoltaic properties of GaAs/Si cells are analyzed by considering the effect of nonuniform dislocation distribution on recombination properties of GaAs thin films on Si substrates. Numerical analysis shows that the effect of majority-carrier trapping must be considered. High efficiency GaAs solar cells with total-area efficiency of over 20% on Si substrates can be realized if dislocation density can be reduced to less than 5/times/10/sup 5/ cm/sup /minus/2/.

  13. Efficiency considerations for polycrystalline GaAs thin-film solar cells

    SciTech Connect (OSTI)

    Yamaguchi, M.; Itoh, Y.

    1986-07-01

    The effect of grain boundaries upon the efficiency of polycrystalline GaAs thin-film solar cells is analyzed. Solar-cell properties are calculated on a simple model where grain boundaries act as recombination centers to reduce the minority-carrier diffusion length in the solar cell's active layer and increase the space-charge layer recombination current. An effective diffusion length is expressed in terms of grain size, allowing the calculation of short-circuit current density and open-circuit voltage. Excellent agreement is obtained between theory and experiment. The fabrication of thin-film GaAs solar cells with an efficiency greater than 18% appears to be possible if the grain size in the thin-film GaAs layer with thickness of 3 ..mu..m is larger than 1000 ..mu..m.

  14. Tensile GaAs(111) quantum dashes with tunable luminescence below the bulk bandgap

    SciTech Connect (OSTI)

    Yerino, Christopher D., E-mail: christopher.yerino@yale.edu; Jung, Daehwan; Lee, Minjoo Larry [Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520 (United States); Simmonds, Paul J.; Liang, Baolai [California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Dorogan, Vitaliy G.; Ware, Morgan E.; Mazur, Yuriy I.; Salamo, Gregory J. [Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Huffaker, Diana L. [California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States)

    2014-08-18

    Strain-based band engineering in quantum dots and dashes has been predominantly limited to compressively strained systems. However, tensile strain strongly reduces the bandgaps of nanostructures, enabling nanostructures to emit light at lower energies than they could under compressive strain. We demonstrate the self-assembled growth of dislocation-free GaAs quantum dashes on an InP(111)B substrate, using a 3.8% tensile lattice-mismatch. Due to the high tensile strain, the GaAs quantum dashes luminesce at 110–240?meV below the bandgap of bulk GaAs. The emission energy is readily tuned by adjusting the size of the quantum dashes via deposition thickness. Tensile self-assembly creates new opportunities for engineering the band alignment, band structure, and optical properties of epitaxial nanostructures.

  15. Biexciton emission from single isoelectronic traps formed by nitrogen-nitrogen pairs in GaAs

    SciTech Connect (OSTI)

    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)

    2013-12-04

    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.

  16. ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission

    E-Print Network [OSTI]

    Atwater, Harry

    ORIGINAL ARTICLE Highly efficient GaAs solar cells by limiting light emission angle Emily D Kosten1. This isotropic emission corresponds to a significant entropy increase in the solar cell, with a corresponding drop in efficiency. Here, using a detailed balance model, we show that limiting the emission angle

  17. Ultralong minority-carrier lifetime epitaxial GaAs by photon recycling

    SciTech Connect (OSTI)

    Ahrenkiel, R.K.; Dunlavy, D.J.; Keyes, B. (Solar Energy Research Institute, Golden, Colorado 80401 (US)); Vernon, S.M.; Dixon, T.M.; Tobin, S.P. (Spire Corporation, Bedford, Massachusetts 01730); Miller, K.L.; Hayes, R.E. (Department of Electrical and Computer Engineering, University of Colorado, Boulder, Colorado 80303)

    1989-09-11

    The minority-carrier lifetime has been measured by time-resolved photoluminescence in epitaxial films of GaAs grown by metalorganic chemical vapor deposition. The measured lifetimes in thicker devices are 4 to 6 times the theoretical or radiative lifetime. These long lifetimes are the result of photon recycling or self-generation of the self-absorbed radiation.

  18. Surface Science 415 (1998) 2936 Structural studies of sulfur-passivated GaAs (100)

    E-Print Network [OSTI]

    Zhang, Yanchao

    1998-01-01

    . Keywords: Atomic force microscopy; Gallium arsenide; Low-energy electron diffraction; Roughness; SulfurSurface Science 415 (1998) 29­36 Structural studies of sulfur-passivated GaAs (100) surfaces Abstract We present the results of Auger electron spectroscopy (AES), low-energy electron diffraction (LEED

  19. Dynamics of Subsurface and Surface Chemisorption for B, C, and N on Gaas and Inp 

    E-Print Network [OSTI]

    MENON, M.; Allen, Roland E.

    1991-01-01

    Using Hellmann-Feynman molecular-dynamics simulations, we have investigated interactions of first-row elements with the (110) surfaces of GaAs and InP. We find that these atoms prefer to occupy subsurface sites. The open structure...

  20. Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells

    E-Print Network [OSTI]

    Faraon, Andrei

    Experimental demonstration of enhanced photon recycling in angle-restricted GaAs solar cells Emily, emphasizing the optical nature of the effect. 1 Introduction For ideal solar cells where all recombination. Despite this theoretical prediction, until recently even the highest efficiency solar cells were not close

  1. GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies

    E-Print Network [OSTI]

    Rogers, John A.

    LETTERS GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies and high electron mobilities. Examples range from effi- cient photovoltaic devices1,2 to radio and logic gates on plates of glass, near-infrared imaging devices on wafers of silicon, and photovoltaic

  2. Monolithic integration of optical grade GaAs on Si (001) substrates deeply patterned at a micron scale

    SciTech Connect (OSTI)

    Bietti, Sergio; Scaccabarozzi, Andrea; Bonera, Emiliano; Miglio, Leo; Sanguinetti, Stefano [L-NESS and Dip. di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I–20125 Milano (Italy)] [L-NESS and Dip. di Scienza dei Materiali, Universitá di Milano Bicocca, Via Cozzi 53, I–20125 Milano (Italy); Frigeri, Cesare [CNR-IMEM Institute, Parco Area delle Scienze 37/A, I–43100 Parma (Italy)] [CNR-IMEM Institute, Parco Area delle Scienze 37/A, I–43100 Parma (Italy); Bollani, Monica [CNR–IFN, L–NESS, via Anzani 42, I–22100 Como (Italy)] [CNR–IFN, L–NESS, via Anzani 42, I–22100 Como (Italy); Falub, Claudiu V.; Känel, Hans von [Laboratory for Solid State Physics, ETH Zurich, Schafmattstrasse 16, CH-8093 Zurich (Switzerland)] [Laboratory for Solid State Physics, ETH Zurich, Schafmattstrasse 16, CH-8093 Zurich (Switzerland)

    2013-12-23

    Dense arrays of micrometric crystals, with areal filling up to 93%, are obtained by depositing GaAs in a mask-less molecular beam epitaxy process onto Si substrates. The substrates are patterned into tall, micron sized pillars. Faceted high aspect ratio GaAs crystals are achieved by tuning the Ga adatom for short surface diffusion lengths. The crystals exhibit bulk-like optical quality due to defect termination at the sidewalls. Simultaneously, the thermal strain induced by different thermal expansion parameters of GaAs and Si is fully relieved. This opens the route to thick film applications without crack formation and wafer bowing.

  3. PROJECT PROFILE: 2D Materials for Low Cost Epitaxial Growth of Single Sun Gallium Arsenide (GaAs) Photovoltaics

    Office of Energy Efficiency and Renewable Energy (EERE)

    Low-cost III-V cells will result in a breakthrough in photovoltaic (PV) market by enabling lower LCOE. The project will develop low-cost substrates to template the growth of GaAs.

  4. Strain-driven growth of GaAs(111) quantum dots with low fine structure splitting

    SciTech Connect (OSTI)

    Yerino, Christopher D.; Jung, Daehwan; Lee, Minjoo Larry; Simmonds, Paul J.; Liang, Baolai; Huffaker, Diana L.; Schneider, Christian; Unsleber, Sebastian; Vo, Minh; Kamp, Martin; Höfling, Sven

    2014-12-22

    Symmetric quantum dots (QDs) on (111)-oriented surfaces are promising candidates for generating polarization-entangled photons due to their low excitonic fine structure splitting (FSS). However, (111) QDs are difficult to grow. The conventional use of compressive strain to drive QD self-assembly fails to form 3D nanostructures on (111) surfaces. Instead, we demonstrate that (111) QDs self-assemble under tensile strain by growing GaAs QDs on an InP(111)A substrate. Tensile GaAs self-assembly produces a low density of QDs with a symmetric triangular morphology. Coherent, tensile QDs are observed without dislocations, and the QDs luminescence at room temperature. Single QD measurements reveal low FSS with a median value of 7.6??eV, due to the high symmetry of the (111) QDs. Tensile self-assembly thus offers a simple route to symmetric (111) QDs for entangled photon emitters.

  5. Simulations of Atomic Processes at Semiconductor Surfaces - General-Method and Chemisorption on Gaas(110) 

    E-Print Network [OSTI]

    MENON, M.; Allen, Roland E.

    1988-01-01

    ,??1 EF ?E' 1. Also, one can see in Fig. 1 that cl a i 1Im ln cl ~ ??m' 26 ?EC ! BE", F, =?Im g lnTT; BX Fq ?g FJ, clE ?E.a i E ?E,clC (2.41) (2.42a) as R ?+00, so 1F 2; Bx (2.49} The expression for the electronic force thus simplifies....63,3.45,0) before they are al- lowed to relax. Figure 2 also schematically shows a top view of six possible chemisorption sites on the surface, 0.0. GaAs(110) ?0.5. ?1.0 1.0 0.5 0.0. ?0 5. ?1.0. ?1.5 0 100 200 300 400 500 600 700 800 t GaAs FIG. 2...

  6. The Morphology and Microstructure of Thin-Film GaAs on Mo Substrates

    SciTech Connect (OSTI)

    Jones, K. M.; Al-Jassim, M. M.; Hasoon, F. S.; Venkatasubramanian, R.

    1999-04-26

    The growth of GaAs thin films on Molybdenum foils was investigated in an attempt to find a low-cost substrate for GaAs. The films were grown by metalorganic chemical vapor deposition (MOCVD). The film thickness was in the 2-4{micro}m range, while the deposition temperature was in the 650-825 C range. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the film morphology and microstructure, respectively. The film morphology in general, and the grain size in particular, were found to be strongly dependent on the growth temperature. However, the defect structure observed in these films was relatively insensitive to the growth conditions.

  7. Growth and properties of crystalline barium oxide on the GaAs(100) substrate

    SciTech Connect (OSTI)

    Yasir, M.; Dahl, J.; Lång, 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); Korpijärvi, V.-M.; Polojärvi, 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)

    2013-11-04

    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.

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

    SciTech Connect (OSTI)

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

    2014-09-21

    We present accurate measurements of Ga cation surface diffusion on GaAs surfaces. The measurement method relies on atomic force microscopy measurement of the morphology of nano–disks that evolve, under group V supply, from nanoscale group III droplets, earlier deposited on the substrate surface. The dependence of the radius of such nano-droplets on crystallization conditions gives direct access to Ga diffusion length. We found an activation energy for Ga on GaAs(001) diffusion E{sub A}=1.31±0.15 eV, a diffusivity prefactor of D?=0.53(×2.1±1) cm² s?¹ that we compare with the values present in literature. The obtained results permit to better understand the fundamental physics governing the motion of group III ad–atoms on III–V crystal surfaces and the fabrication of designable nanostructures.

  9. Epitaxial two-dimensional nitrogen atomic sheet in GaAs

    SciTech Connect (OSTI)

    Harada, Yukihiro, E-mail: y.harada@eedept.kobe-u.ac.jp; Yamamoto, Masuki; Baba, Takeshi; Kita, Takashi [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)

    2014-01-27

    We have grown an epitaxial two-dimensional nitrogen (N) atomic sheet in GaAs by using the site-controlled N ?-doping technique. We observed a change of the electronic states in N ?-doped GaAs from the isolated impurity centers to the delocalized impurity band at 1.49?eV with increasing N-doping density. According to the excitation-power- and temperature-dependent photoluminescence (PL) spectra, the emission related to localized levels below the impurity band edge was dominant at low excitation power and temperature, whereas the effects of the localized levels can be neglected by increasing the excitation power and temperature. Furthermore, a clear Landau shift of the PL-peak energy was observed at several Tesla in the Faraday configuration, in contrast to the case in the impurity limit.

  10. Patterned Exfoliation of GaAs Based on Masked Helium Implantation and Subsequent Rapid Thermal Annealing

    SciTech Connect (OSTI)

    Woo, H. J.; Choi, H. W.; Kim, G. D.; Hong, W.; Kim, J. K.

    2009-03-10

    A method of patterning single crystal GaAs based on ion implantation induced selective area exfoliation is suggested. Samples were implanted with 200-500 keV helium ions to a fluence range of 2-4x10{sup 16} He{sup +}/cm{sup 2} at room temperature through masks of Ni mesh (40 {mu}m opening) or stainless steel wire (50 {mu}m in diameter), and subsequent rapid thermal annealing at 350-500{open_square} resulted in expulsion of ion beam exposed material. The influences of ion energy, ion fluence, implantation temperature, subsequent annealing conditions (temperature and ramp rate), and mask pattern and its orientation with GaAs lattice on the patterned exfoliation were examined.

  11. Molecular Beam Epitaxial Growth of GaAs on (631) Oriented Substrates

    SciTech Connect (OSTI)

    Cruz Hernandez, Esteban; Rojas Ramirez, Juan-Salvador; Contreras Hernandez, Rocio; Lopez Lopez, Maximo; Pulzara Mora, Alvaro; Mendez Garcia, Victor H.

    2007-02-09

    In this work, we report the study of the homoepitaxial growth of GaAs on (631) oriented substrates by molecular beam epitaxy (MBE). We observed the spontaneous formation of a high density of large scale features on the surface. The hilly like features are elongated towards the [-5, 9, 3] direction. We show the dependence of these structures with the growth conditions and we present the possibility of to create quantum wires structures on this surface.

  12. High quality GaAs single photon emitters on Si substrate

    SciTech Connect (OSTI)

    Bietti, S.; Sanguinetti, S. [Dipartimento di Scienza dei Materiali and L-NESS, Università, di Milano Bicocca, Via Cozzi 53,I-20125 Milano (Italy); Cavigli, L.; Accanto, N.; Vinattieri, A. [Dipartimento di Fisica e Astronomia, LENS and CNISM, Università, di Firenze, Via Sansone 1, I-50019 Firenze (Italy); Minari, S.; Abbarchi, M. [Dipartimento di Fisica e Astronomia, LENS and CNISM, Universita di Firenze, Via Sansone 1, I-50019 Firenze (Italy); Isella, G. [Dipartimento di Fisica and L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy); Frigeri, C. [CNR-IMEM Institute, Parco Area delle Scienze 31/A, 43100 Parma (Italy); Gurioli, M. [Dipartimento di Fisica e Astronomia, LENS and CNISM, Universita, di Firenze, Via Sansone 1, I-50019 Firenze (Italy)

    2013-12-04

    We describe a method for the direct epitaxial growth of a single photon emitter, based on GaAs quantum dots fabricated by droplet epitaxy, working at liquid nitrogen temperatures on Si substrates. The achievement of quantum photon statistics up to T=80 K is directly proved by antibunching in the second order correlation function as measured with a H anbury Brown and Twiss interferometer.

  13. Static atomic displacements in a CdTe epitaxial layer on a GaAs substrate

    SciTech Connect (OSTI)

    Horning, R.D.; Staudenmann, J.

    1987-05-25

    A (001)CdTe epitaxial layer on a (001)GaAs substrate was studied by x-ray diffraction between 10 and 360 K. The CdTe growth took place at 380 /sup 0/C in a vertical gas flow metalorganic chemical vapor deposition reactor. Lattice parameters and integrated intensities of both the substrate and the epitaxial layer using the (00l) and (hhh) Bragg reflections reveal three important features. Firstly, the GaAs substrate does not exhibit severe strain after deposition and it is as perfect as a bulk GaAs. Secondly, the CdTe unit cell distorts tetragonally with a/sub perpendicular/>a/sub parallel/ below 300 K. The decay of the (00l) reflection intensities as a function of the temperature yields a Debye temperature of 142 K, the same value as for bulk CdTe. Thirdly, a temperature-dependent isotropic static displacement of the Cd and the Te atoms is introduced to account for the anomalous behavior of the (hhh) intensities.

  14. Effects of heavy impurity doping on electron injection in p/sup +/-n GaAs diodes

    SciTech Connect (OSTI)

    Klausmeier-Brown, M.E.; Lundstrom, M.S.; Melloch, M.R.; Tobin, S.P.

    1988-06-27

    Measurements of electron injection currents in p/sup +/-n diodes are presented for a range of p-type dopant concentrations. A successive etch technique was used to characterize the electron injection current in terms of the product (n/sub o/D/sub n/). Measurements are presented for Zn-doped GaAs solar cells with p-layer hole concentrations in the range 6.3 x 10/sup 17/-1.3 x 10/sup 19/ cm/sup -3/. The results demonstrate that so-called band-gap narrowing effects substantially increase the injected electron current in heavily doped p-type GaAs. These heavy doping effects must be accounted for in the modeling and design of GaAs solar cells and heterostructure bipolar transistors.

  15. Focusing effect of bent GaAs crystals for gamma-ray Laue lenses: Monte Carlo and experimental results

    E-Print Network [OSTI]

    Virgilli, E; Rosati, P; Bonnini, E; Buffagni, E; Ferrari, C; Stephen, J B; Caroli, E; Auricchio, N; Basili, A; Silvestri, S

    2015-01-01

    We report on results of observation of the focusing effect from the planes (220) of Gallium Arsenide (GaAs) crystals. We have compared the experimental results with the simulations of the focusing capability of GaAs tiles through a developed Monte Carlo. The GaAs tiles were bent using a lapping process developed at the cnr/imem - Parma (Italy) in the framework of the laue project, funded by ASI, dedicated to build a broad band Laue lens prototype for astrophysical applications in the hard X-/soft gamma-ray energy range (80-600 keV). We present and discuss the results obtained from their characterization, mainly in terms of focusing capability. Bent crystals will significantly increase the signal to noise ratio of a telescope based on a Laue lens, consequently leading to an unprecedented enhancement of sensitivity with respect to the present non focusing instrumentation.

  16. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    SciTech Connect (OSTI)

    Dutta, P. Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V.; Zheng, N.; Ahrenkiel, P.; Martinez, J.

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ?10{sup 7?}cm{sup ?2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300?cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  17. Band Structure of Strain-Balanced GaAsBi/GaAsN Super-lattices on GaAs

    SciTech Connect (OSTI)

    Hwang, J.; Phillips, J. D.

    2011-05-31

    GaAs alloys with dilute content of Bi and N provide a large reduction in band-gap energy with increasing alloy composition. GaAsBi/GaAsN heterojunctions have a type-II band alignment, where superlattices based on these materials offer a wide range for designing effective band-gap energy by varying superlattice period and alloy composition. The miniband structure and effective band gap for strain-balanced GaAsBi/GaAsN superlattices with effective lattice match to GaAs are calculated for alloy compositions up to 5% Bi and N using the k·p method. The effective band gap for these superlattices is found to vary between 0.89 and 1.32 eV for period thickness ranging from 10 to 100 Å. The joint density of states and optical absorption of a 40/40 Å GaAs0.96Bi0.04/GaAs0.98N0.02 superlattice are reported demonstrating a ground-state transition at 1.005 eV and first excited transition at 1.074 eV. The joint density of states is similar in magnitude to GaAs, while the optical absorption is approximately one order of magnitude lower due to the spatially indirect optical transition in the type-II structure. The GaAsBi/GaAsN system may provide a new material system with lattice match to GaAs in a spectral range of high importance for optoelectronic devices including solar cells, photodetectors, and light emitters.

  18. Optical properties of GaAs 2D hexagonal and cubic photonic crystal

    SciTech Connect (OSTI)

    Arab, F. Assali, A.; Grain, R.; Kanouni, F.

    2015-03-30

    In this paper we present our theoretical study of 2D hexagonal and cubic rods GaAs in air, with plan wave expansion (PWE) and finite difference time domain (FDTD) by using BandSOLVE and FullWAVE of Rsoft photonic CAD package. In order to investigate the effect of symmetry and radius, we performed calculations of the band structures for both TM and TE polarization, contour and electromagnetic propagation and transmission spectra. Our calculations show that the hexagonal structure gives a largest band gaps compare to cubic one for a same filling factor.

  19. Order from Chaos: (alpha)-Fe(001) Growth on GaAs(001)

    SciTech Connect (OSTI)

    Tobin, J G; Yu, S W; Morton, S A; Waddill, G D; Thompson, J D; Neal, J R; Shen, T H

    2008-02-08

    The growth of Fe upon GaAs(001) has been studied with Spin-Resolved Photoelectron Spectroscopy (SRPES), Photoelectron Spectroscopy (PES) and X-ray Magnetic Linear Dichroism (XMLD) in PES. Despite evidence of atomic level disorder such as intermixing, an over-layer with the spectroscopic signature of {alpha}-Fe(001), with a bcc real space ordering, is obtained. The results will be discussed in light of the possibility of using such films as a spin polarized source in device applications.

  20. Magnetism and transport properties of epitaxial Fe-Ga thin films on GaAs(001)

    SciTech Connect (OSTI)

    Duong Anh Tuan; Shin, Yooleemi; Cho, Sunglae; Dang Duc Dung; Vo Thanh Son

    2012-04-01

    Epitaxial Fe-Ga thin films in disordered bcc {alpha}-Fe crystal structure (A2) have been grown on GaAs(001) by molecular beam epitaxy. The saturated magnetization (M{sub S}) decreased from 1371 to 1105 kA/m with increasing Ga concentration from 10.5 to 24.3 % at room temperature. The lattice parameter increased with the increase in Ga content because of the larger atomic radius of Ga atom than that of Fe. The increase in carrier density with Ga content caused in lower resistivity.

  1. Perpendicularly magnetized {tau}-MnAl (001) thin films epitaxied on GaAs

    SciTech Connect (OSTI)

    Nie, S. H.; Zhu, L. J.; Lu, J.; Pan, D.; Wang, H. L.; Yu, X. Z.; Xiao, J. X.; Zhao, J. H.

    2013-04-15

    Perpendicularly magnetized {tau}-MnAl films have been epitaxied on GaAs (001) by molecular-beam epitaxy. Crystalline quality and magnetic properties of the samples were strongly dependent on growth temperature. The highest coercivity of 10.7 kOe, saturation magnetization of 361.4 emu/cm{sup 3}, perpendicular magnetic anisotropy constant of 13.65 Merg/cm{sup 3}, and magnetic energy product of 4.44 MGOe were achieved. These tunable magnetic properties make MnAl films valuable as excellent and cost-effective alternative for not only high density perpendicular magnetic recording storage and spintronics devices but also permanent magnets.

  2. High-efficiency GaAs solar cells grown by molecular-beam epitaxy

    SciTech Connect (OSTI)

    Melloch, M.R. (School of Electrical Engineering, Purdue University, West Lafayette, Indiana 47907 (USA)); Tobin, S.P. (Spire Corporation, Patriots Park, Bedford, Massachusetts 01730 (USA)); Stellwag, T.B. (School of Electrical Engineering, Purdue University, West Lafayette, Indiana 47907 (USA)); Bajgar, C. (Spire Corporation, Patriots Park, Bedford, Massachusetts 01730 (USA)); Keshavarzi, A.; Lundstrom, M.S. (School of Electrical Engineering, Purdue University, West Lafayette, Indiana 47907 (USA)); Emery, K. (Solar Energy Research Institute, Golden, Colorado 80401 (USA))

    1990-03-01

    Previously, solar cells fabricated from molecular-beam epitaxually (MBE)-grown material have been inferior in performance to those fabricated from metalorganic chemical vapor deposited (MOCVD) material. We have obtained 1-sun air mass (AM) 1.5 efficiencies of 23.8% for 0.25 cm{sup 2} GaAs solar cells fabricated on MBE-grown material. This is the first solar cell fabricated on MBE material which is of comparable performance to solar cells fabricated on MOCVD material. Details of the MBE system preparation and film growth procedure along with a detailed evaluation of the solar cells will be presented.

  3. High excitation power photoluminescence studies of ultra-low density GaAs quantum dots

    SciTech Connect (OSTI)

    Sonnenberg, D.; Graf, A.; Paulava, V.; Heyn, Ch.; Hansen, W. [Institut für Angewandte Physik und Zentrum für Mikrostrukturforschung, Universität Hamburg, Jungiusstr. 11, 20355 Hamburg (Germany)

    2013-12-04

    We fabricate GaAs epitaxial quantum dots (QDs) by filling of self-organized nanoholes in AlGaAs. The QDs are fabricated under optimized process conditions and have ultra-low density in the 10{sup 6} cm{sup ?2} regime. At low excitation power the optical emission of single QDs exhibit sharp excitonic lines, which are attributed to the recombination of excitonic and biexcitonic states. High excitation power measurements reveal surprisingly broad emission lines from at least six QD shell states.

  4. Optoelectronic simulation of GaAs solar cells with angularly selective filters

    SciTech Connect (OSTI)

    Kraus, Tobias Höhn, Oliver; Hauser, Hubert; Bläsi, Benedikt

    2014-02-07

    We discuss the influence of angularly selective filters on thin film gallium arsenide solar cells. For this reason, the detailed balance model was refined to fit our needs with respect to Auger recombination, reflection, transmission, and realistic absorption. For calculating real systems, an approach was made to include optical effects of angularly selective filters into electron-hole dynamic equations implemented in PC1D, a one dimensional solar cell calculation tool. With this approach, we find a relative V{sub oc} increase of 5% for an idealized 100?nm GaAs cell, including Auger recombination.

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

    SciTech Connect (OSTI)

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

    2013-08-12

    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.

  6. An approach toward 25-percent efficient GaAs heteroface solar cells

    SciTech Connect (OSTI)

    Ringel, S.A.; Rohatgi, A. (Georgia Inst. of Tech., Atlanta, GA (USA). School of Electrical Engineering); Tobin, S.P. (Spire Corp., Bedford, MA (USA))

    1989-07-01

    In order to approach one-sun 25-percent efficiency in GaAs solar cells, it is necessary to improve the basic understanding of internal loss mechanisms by a combination of characterization techniques and computer models. A methodology is developed to measure and evaluate minority-carrier transport properties such as lifetime and recombination velocity throughout the device structure in a 21.2-percent GaAs cell. It is found that this cell has a recombination velocity of 1.25 X 10/sup 5/ cm/s at the AlGaAs/GaAs interface and a base minority-carrier lifetime of 8 ns. Guidelines are provided to increase the efficiency of this cell to 24 percent with slightly increased surface passivation and base lifetime using effective recombination velocity and device modeling computer programs. Further device modeling is performed to show that efficiencies of 25 percent can be obtained using a modified heteroface structure with a moderate surface recombination velocity of 1 X 10/sup 4/ cm/s if lifetime limiting mechanisms and their relation to device design are fully understood.

  7. Thermal degradation mechanisms in GaAs solar cells with high-temperature contacts

    SciTech Connect (OSTI)

    Tobin, S.P.; Bajgar, C.; Vernon, S.M.; Keavney, C.J.; Chung, M.A.; Ruby, D.S.

    1988-01-01

    This objective of this work was to characterize the thermal stability of GaAs solar cells with high-temperature contacts. High-temperature stability is important for threat environments in space, for compatibility with high-temperature assembly techniques, and for enhanced reliability of cells. Our contact system, described previously, relies on a Pt solid-phase ohmic contact, a TiN barrier layer, and an Au conductor, with contact to a heavily doped p-GaAs contact layer. The behavior of both flat-plate and concentrator cells has been characterized as a function of temperature (400-600/degree/C) and time (5-15 minutes) of the anneal. We find that GaAs cells experience minimal electrical degradation up to 550/degree/C for 5 minutes, or to 490/degree/C for 15 minutes. Increases in the 2kT perimeter dark current are responsible for small decreases in Voc and FF up to these temperatures. At higher temperatures a drastic decrease in efficiency is caused by metallurgical reactions at isolated regions along the grid lines. The reaction, which appears to involve Au-Ga, is initiated at the edges of the grid lines. Away from edges, the contacts are metallurgically stable to at least 600/degree/C. 4 refs., 8 figs., 4 tabs.

  8. GaAs buffer layer technique for vertical nanowire growth on Si substrate

    SciTech Connect (OSTI)

    Xu, Xiaoqing Parizi, Kokab B.; Huo, Yijie; Kang, Yangsen; Philip Wong, H.-S.; Li, Yang

    2014-02-24

    Gold catalyzed vapor-liquid-solid method is widely applied to III–V nanowire (NW) growth on Si substrate. However, the easy oxidation of Si, possible Si contamination in the NWs, high defect density in the NWs, and high sensitivity of the NW morphology to growth conditions largely limit its controllability. In this work, we developed a buffer layer technique by introducing a GaAs thin film with predefined polarity as a template. It is found that samples grown on these buffer layers all have high vertical NW yields in general, due to the single-orientation of the buffer layers. Low temperature buffer with smoother surface leads to highest yield of vertical NWs, while high temperature (HT) buffer with better crystallinity results in perfect NW quality. The defect-free property we observed here is very promising for optoelectronic device applications based on GaAs NW. Moreover, the buffer layers can eliminate Si contamination by preventing Si-Au alloy formation and by increasing the thickness of the Si diffusion barrier, thus providing more flexibility to vertical NW growth. The buffer layer technique we demonstrated here could be easily extended to other III-V on Si system for electronic and photonic applications.

  9. Doped Contacts for High-Longevity Optically Activated, High Gain GaAs Photoconductive Semiconductor Switches

    SciTech Connect (OSTI)

    MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; O'MALLEY,MARTIN W.; HELGESON,WESLEY D.; BROWN,DARWIN JAMES; HJALMARSON,HAROLD P.; BACA,ALBERT G.; THORNTON,R.L.; DONALDSON,R.D.

    1999-12-17

    The longevity of high gain GaAs photoconductive semiconductor switches (PCSS) has been extended to over 100 million pulses. This was achieved by improving the ohmic contacts through the incorporation of a doped layer that is very effective in the suppression of filament formation, alleviating current crowding. Damage-free operation is now possible with virtually infinite expected lifetime at much higher current levels than before. The inherent damage-free current capacity of the bulk GaAs itself depends on the thickness of the doped layers and is at least 100A for a dopant diffusion depth of 4pm. The contact metal has a different damage mechanism and the threshold for damage ({approx}40A) is not further improved beyond a dopant diffusion depth of about 2{micro}m. In a diffusion-doped contact switch, the switching performance is not degraded when contact metal erosion occurs, unlike a switch with conventional contacts. This paper will compare thermal diffusion and epitaxial growth as approaches to doping the contacts. These techniques will be contrasted in terms of the fabrication issues and device characteristics.

  10. The influence of electron irradiation on electron holography of focused ion beam milled GaAs p-n junctions

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    The influence of electron irradiation on electron holography of focused ion beam milled GaAs p beam electron diffraction CBED , a value for Vbi in the electri- cally "active" part of the specimen, United Kingdom Received 16 November 2006; accepted 10 March 2007; published online 14 May 2007 Electron

  11. Critical dimension improvement of plasma enhanced chemical vapor deposition silicon nitride thin films in GaAs devices

    E-Print Network [OSTI]

    Shapira, Yoram

    , Faculty of Engineering, Tel-Aviv University, Ramat-Aviv 69978, Israel Abstract Silicon nitride thin films. This is important since GaAs processing does not tolerate higher temperatures. However, using hydride source gases and Engineering B102 (2003) 352Á/357 www.elsevier.com/locate/mseb 0921-5107/03/$ - see front matter # 2003

  12. Tandem Solar Cells Using GaAs Nanowires on Si: Design, Fabrication, and Observation of Voltage Addition

    E-Print Network [OSTI]

    Zhou, Chongwu

    for high-efficiency, low-cost multijunction solar cells. KEYWORDS: Tandem solar cell, Ga so that the efficiency advantage is outweighed by the low cost of Si solar cells for manyTandem Solar Cells Using GaAs Nanowires on Si: Design, Fabrication, and Observation of Voltage

  13. IEEE ELECTRON DEVICE LETTERS, VOL. 34, NO. 4, APRIL 2013 487 GaAs Enhancement-Mode NMOSFETs Enabled by

    E-Print Network [OSTI]

    IEEE ELECTRON DEVICE LETTERS, VOL. 34, NO. 4, APRIL 2013 487 GaAs Enhancement-Mode NMOSFETs Enabled, and P. D. Ye, Fellow, IEEE Abstract--We demonstrate high-performance enhancement­ mode (E-mode) Ga at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/LED.2013.2244058 Fig. 1. (a) Cross

  14. I-V analysis of high-energy lithium-ion-irradiated Si and GaAs solar cells

    E-Print Network [OSTI]

    A. Meulenberg Jr; B. Jayashree; Ramani; M. C. Radhakrishna; A. K. Saif

    2007-09-07

    Space-grade Si and GaAs solar cells were irradiated with 15 and 40 MeV lithium ions. Dark-IV analysis (with and without illumination) reveals differences in the effects of such irradiation on the different cell types

  15. THIN FILM SOLAR CELLS AND A REVIEW OF RECENT RESULTS ON GaAs By PAUL RAPPAPORT,

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    154. THIN FILM SOLAR CELLS AND A REVIEW OF RECENT RESULTS ON GaAs By PAUL RAPPAPORT, RCA PHYSIQUE APPLIQUÃ?E TOME 1, SEPTEMBRE 1966, PAGE ' Two of the most urgent requirements of future solar cells are lower cost and lighter weight. Pre- sent cost of solar cells is in the s 200 to $ 400/watt range, which

  16. Difference-frequency generation in the field of a few-cycle laser pulse propagating in a GaAs crystal with a domain structure

    SciTech Connect (OSTI)

    Oganesyan, David L; Vardanyan, Aleksandr O; Oganesyan, G D

    2013-06-30

    Difference-frequency generation in a GaAs crystal with a periodic domain structure in the field of a few-cycle laser pulse is considered for the case of weakly pronounced material dispersion. The straight-line method is used to solve numerically the system of coupled nonlinear partial differential equations describing the evolution of the electric field of this laser pulse in GaAs crystals with periodic and chirped domain structures. It is shown that application of a GaAs crystal with a chirped domain structure makes it possible to control the frequency-modulation law for a broadband differencefrequency pulse. (nonlinear optical phenomena)

  17. GaAs micro-pyramids serving as optical micro-cavities

    SciTech Connect (OSTI)

    Karl, M.; Beck, T.; Li, S.; Hu, D. Z.; Schaadt, D. M.; Kalt, H.; Hetterich, M.

    2010-01-04

    An efficient light-matter coupling requires high-quality (Q) micro-cavities with small mode volume. We suggest GaAs micro-pyramids placed on top of AlAs/GaAs distributed Bragg reflectors to be promising candidates. The pyramids were fabricated by molecular-beam epitaxy, electron-beam lithography and a subsequent wet-chemical etching process using a sacrificial AlAs layer. Measured Q-factors of optical modes in single pyramids reach values up to 650. A finite-difference time-domain simulation assuming a simplified cone-shaped geometry suggests possible Q-factors up to 3600. To enhance the light confinement in the micro-pyramids we intend to overgrow the pyramidal facets with a Bragg mirror--results of preliminary tests are given.

  18. Evolution of superclusters and delocalized states in GaAs1–xNx

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

    Fluegel, B.; Alberi, K.; Beaton, D. A.; Crooker, S. A.; Ptak, A. J.; Mascarenhas, A.

    2012-11-01

    The evolution of individual nitrogen cluster bound states into an extended state infinite supercluster in dilute GaAs1–xNx was probed through temperature and intensity-dependent, time-resolved and magnetophotoluminescence (PL) measurements. Samples with compositions less than 0.23% N exhibit PL behavior that is consistent with emission from the extended states of the conduction band. Near a composition of 0.23% N, a discontinuity develops between the extended state PL peak energy and the photoluminescence excitation absorption edge. The existence of dual localized/delocalized state behavior near this composition signals the formation of an N supercluster just below the conduction band edge. The infinite supercluster ismore »fully developed by 0.32% N.« less

  19. Fano Resonance in GaAs 2D Photonic Crystal Nanocavities

    SciTech Connect (OSTI)

    Valentim, P. T.; Guimaraes, P.S. S.; Luxmoore, I. J.; Szymanski, D.; Whittaker, D. M.; Fox, A. M.; Skolnick, M. S.; Vasco, J. P.; Vinck-Posada, H.

    2011-12-23

    We report the results of polarization resolved reflectivity experiments in GaAs air-bridge photonic crystals with L3 cavities. We show that the fundamental L3 cavity mode changes, in a controlled way, from a Lorentzian symmetrical lineshape to an asymmetrical form when the linear polarization of the incident light is rotated in the plane of the crystal. The different lineshapes are well fitted by the Fano asymmetric equation, implying that a Fano resonance is present in the reflectivity. We use the scattering matrix method to model the Fano interference between a localized discrete state (the cavity fundamental mode) and a background of continuum states (the light reflected from the crystal slab in the vicinity of the cavity) with very good agreement with the experimental data.

  20. Epitaxial lift-off of quantum dot enhanced GaAs single junction solar cells

    SciTech Connect (OSTI)

    Bennett, Mitchell F.; Bittner, Zachary S.; Forbes, David V.; Hubbard, Seth M.; Rao Tatavarti, Sudersena; Wibowo, Andree; Pan, Noren; Chern, Kevin; Phillip Ahrenkiel, S.

    2013-11-18

    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}.

  1. Efficiency calculations of thin-film GaAs solar cells on Si substrates

    SciTech Connect (OSTI)

    Yamaguchi, M.; Amano, C.

    1985-11-01

    Dislocation effect upon the efficiency of single-crystal thin-film AlGaAs-GaAs heteroface solar cells on Si substrates is analyzed. Solar-cell properties are calculated based on a simple model; in the model, dislocations act as recombination centers to reduce the minority-carrier diffusion length in each layer and increase the space-charge layer recombination current. Numerical analysis is also carried out to optimize thin-film AlGaAs-GaAs heteroface solar-cell structures. The fabrication of thin-film AlGaAs-GaAs heteroface solar cells with a practical efficiency larger than 18% on Si substrates appears possible if the dislocation density in the thin-film GaAs layer is less than 10/sup 6/ cm/sup -2/.

  2. Thin film GaAs solar cells on glass substrates by epitaxial liftoff

    SciTech Connect (OSTI)

    Lee, X.Y.; Goertemiller, M.; Boroditsky, M.; Ragan, R.; Yablonovitch, E.

    1997-02-01

    In this work, we describe the fabrication and operating characteristics of GaAs/AlGaAs thin film solar cells processed by the epitaxial liftoff (ELO) technique. This technique allows the transfer of these cells onto glass substrates. The performance of the lifted-off solar cell is demonstrated by means of electrical measurements under both dark and illuminated conditions. We have also optimized the light trapping conditions in this direct-gap material. The results show that good solar absorption is possible in active layers as thin as 0.32 {mu}m. In such a thin solar cell, the open circuit voltage would be enhanced. We believe that the combination of an epitaxial liftoff thin GaAs film, and nano-texturing can lead to record breaking performance. {copyright} {ital 1997 American Institute of Physics.}

  3. High quality metamorphic graded buffers with lattice-constants intermediate to GaAs an InP for device applications

    E-Print Network [OSTI]

    Lee, Kenneth Eng Kian

    2009-01-01

    We have investigated the use of a continuous, linear grading scheme for compositionally-graded metamorphic InxGal-As buffers on GaAs, which can be used as virtual substrates for optical emitters operating at wavelengths > ...

  4. Simulation of quantum dots size and spacing effect for intermediate band solar cell application based on InAs quantum dots arrangement in GaAs

    SciTech Connect (OSTI)

    Hendra, P. I. B. Rahayu, F. Darma, Y.

    2014-03-24

    Intermediate band solar cell (IBSC) has become a promising technology in increasing solar cell efficiency. In this work we compare absorption coefficient profile between InAs quantum dots with GaAs bulk. We calculate the efficiency of GaAs bulk and GaAs doped with 2, 5, and 10 nm InAs quantum dot. Effective distances in quantum dot arrangement based on electron tunneling consideration were also calculated. We presented a simple calculation method with low computing power demand. Results showed that arrangement of quantum dot InAs in GaAs can increase solar cell efficiency from 23.9 % initially up to 60.4%. The effective distance between two quantum dots was found 2 nm in order to give adequate distance to prevent electron tunneling and wave functions overlap.

  5. Doping and electronic properties of GaAs grown by close-spaced vapor transport from powder sources for scalable III–V photovoltaics

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

    Ritenour, Andrew J.; Boucher, Jason W.; DeLancey, Robert; Greenaway, Ann L.; Aloni, Shaul; Boettcher, Shannon W.

    2014-09-01

    We report the use of a simple close-spaced vapor transport technique for the growth of high-quality epitaxial GaAs films using potentially inexpensive GaAs powders as precursors. The free carrier type and density (1016 to 1019 cm–3) of the films were adjusted by addition of Te or Zn powder to the GaAs source powder. We show using photoelectrochemical and electron beam-induced current analyses that the minority carrier diffusion lengths of the n- and p-GaAs films reached ~3 ?m and ~8 ?m, respectively. Hall mobilities approach those achieved for GaAs grown by metal–organic chemical vapor deposition, 1000–4200 cm2 V–1 s–1 for n-GaAsmore »and 50–240 cm V–1 s–1 for p-GaAs depending on doping level. We conclude that the electronic quality of GaAs grown by close-spaced vapor transport is similar to that of GaAs made using conventional techniques and is thus sufficient for high-performance photovoltaic applications.« less

  6. Doping and electronic properties of GaAs grown by close-spaced vapor transport from powder sources for scalable III–V photovoltaics

    SciTech Connect (OSTI)

    Ritenour, Andrew J.; Boucher, Jason W.; DeLancey, Robert; Greenaway, Ann L.; Aloni, Shaul; Boettcher, Shannon W.

    2014-09-01

    We report the use of a simple close-spaced vapor transport technique for the growth of high-quality epitaxial GaAs films using potentially inexpensive GaAs powders as precursors. The free carrier type and density (1016 to 1019 cm–3) of the films were adjusted by addition of Te or Zn powder to the GaAs source powder. We show using photoelectrochemical and electron beam-induced current analyses that the minority carrier diffusion lengths of the n- and p-GaAs films reached ~3 ?m and ~8 ?m, respectively. Hall mobilities approach those achieved for GaAs grown by metal–organic chemical vapor deposition, 1000–4200 cm2 V–1 s–1 for n-GaAs and 50–240 cm V–1 s–1 for p-GaAs depending on doping level. We conclude that the electronic quality of GaAs grown by close-spaced vapor transport is similar to that of GaAs made using conventional techniques and is thus sufficient for high-performance photovoltaic applications.

  7. Deep level defects in n-type GaAsBi and GaAs grown at low temperatures

    SciTech Connect (OSTI)

    Mooney, P. M.; Watkins, K. P.; Jiang, Zenan; Basile, A. F.; Lewis, R. B.; Bahrami-Yekta, V.; Masnadi-Shirazi, M.; Beaton, D. A.; Tiedje, T.

    2013-04-07

    Deep level defects in n-type GaAs{sub 1-x}Bi{sub x} having 0 < x < 0.012 and GaAs grown by molecular beam epitaxy (MBE) at substrate temperatures between 300 and 400 Degree-Sign C have been investigated by Deep Level Capacitance Spectroscopy. Incorporating Bi suppresses the formation of an electron trap with activation energy 0.40 eV, thus reducing the total trap concentration in dilute GaAsBi layers by more than a factor of 20 compared to GaAs grown under the same conditions. We find that the dominant traps in dilute GaAsBi layers are defect complexes involving As{sub Ga}, as expected for MBE growth at these temperatures.

  8. Proposed measurement of spin currents in a GaAs crystal using the electro-optical Pockels effect

    SciTech Connect (OSTI)

    Zhang, Xingchu; Zheng, Yongjun; She, Weilong

    2014-07-14

    A new method for measuring spin currents is proposed, based on the linear electro-optic (Pockels) effect caused by the additional second-order nonlinear electric susceptibility (electro-optic tensor) generated by the spin currents. The non-zero elements of electro-optic tensor induced by spin currents in GaAs crystal are calculated, and the wave coupling theory of linear electro-optic effect is used to analyze the polarization change of a probe beam. The numerical results show that, for a linearly polarized probe beam with a frequency close to the band gap of GaAs crystal, its polarization rotation can be as large as 14??rad under an applied electric field of about 350?V/mm. This effect should offer an alternative detection method for spintronics.

  9. Influence of perimeter recombination on high-efficiency GaAs p/n heteroface solar cells

    SciTech Connect (OSTI)

    De Moulin, P.D.; Lundstrom, M.S.; Carpenter, M.S.; Melloch, M.R. (School of Electrical Engineering, Purdue Univ., West Lafayette, IN (US)); Tobin, S.P. (Spire Corp., Bedford, MA (US))

    1988-08-01

    Perimeter recombination currents have been characterized for 0.5 x 0.5- and 2 x 2-cm/sup 2/ p/n GaAs solar cells. Measurements show that perimeter recombination dominates the n = 2 dark current component of these high-efficiency solar cells. The results also suggest that perimeter recombination will be substantial even in much larger area solar cells. Although little influence on open-circuit voltage is expected, perimeter recombination may adversely affect the cell's one-sun fill factor. Because of its importance to one-sun applications, recombination at the junction perimeter must be suppressed before GaAs solar cells approach their limiting conversion efficiencies.

  10. Analysis of strain relaxation by microcracks in epitaxial GaAs grown on Ge/Si substrates

    SciTech Connect (OSTI)

    Colombo, D.; Grilli, E.; Guzzi, M.; Sanguinetti, S.; Marchionna, S.; Bonfanti, M.; Fedorov, A.; Kaenel, H. von; Isella, G.; Mueller, E. [CNISM and L-NESS, Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, Via Cozzi 53, I-20125, Milano (Italy); CNISM and L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, via Anzani 52, I-22100 Como (Italy); Laboratorium fuer Festkoerperphysik, ETH Zuerich, CH-8093 Zuerich (Switzerland)

    2007-05-15

    A detailed spectroscopic and morphological study of GaAs epitaxial layers grown by molecular beam epitaxy on Ge buffer layers deposited by low energy plasma enhanced chemical vapor deposition on Si is presented. The aim is to understand the nature of thermal strain relaxation induced by crack formation in the epilayers. The comparison of the experimental data on the spatial strain relaxation pattern with the theoretical prediction from a purely elastic model indicates that strain relaxation around cracks arises from two contributions. At short distances the main contribution is essentially plastic, due to the presence of extended defects. At large distances, on the contrary, elastic relaxation seems to dominate. It is also shown that GaAs grown on Ge/Si substrates is in a state of metastable strain as a consequence of the fact that cracks relax the thermal tensile strain only locally.

  11. Quantum efficiency temporal response and lifetime of a GaAs cathode in SRF electron gun

    SciTech Connect (OSTI)

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

    2010-05-23

    RF electron guns with a strained super lattice GaAs cathode can generate polarized electron beam of higher brightness and lower emittance than do DC guns, due to their higher field gradient at the cathode's surface. In a normal conducting RF gun, the extremely high vaccum required by these cathodes can not be met. We report on an experiment with a superconducting SRF gun, which can maintain a vacuum of nearly 10-12 torr because of cryo-pumping at the temperature of 4.2K. With conventional activation, we obtained a QE of 3% at 532 nm, with lifetime of nearly 3 days in the preparation chamber. We plan to use this cathode in a 1.3 GHz 1/2 cell SRF gun to study its performance. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper. Future particle accelerators such as eRHIC and ILC require high brightness, high current polarized electrons Recently, using a superlattice crystal, the maximum polarization of 95% was reached. Activation with Cs,O lowers the electron affinity and makes it energetically possible for all the electrons excited in to the conduction band and reach the surface to escape into the vacuum. Presently the polarized electron sources are based on DC gun, such as that at the CEBAF at Jlab. In these devices, the life time of the cathode is extended due to the reduced back bombardment in their UHV conditions. However, the low accelerating gradient of the DC guns lead to poor longitudinal emittance. The higher accelerating gradient of the RF gun generates low emittance beams. Superconducting RF guns combine the excellent vacuum conditions of the DC guns with the higher accelerating gradients of the RF guns and provide potentially a long lived cathode with very low transverse and longitudinal emittance. In our work at BNL, we successfully activated the GaAs. The quantum efficient is 3% at 532 nm and is expected to improve further. In addition, we studied the multipacting at the location of cathode. A new model based on the Forkker-Planck equation which can estimate the bunch length of the electron beam is discussed in this paper.

  12. Heat load of a P-doped GaAs photocathode in SRF electron gun

    SciTech Connect (OSTI)

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

    2010-05-23

    Many efforts were made over the last decades to develop a better polarized electron source for the high energy physics. Several laboratories operate DC guns with the Gallium-Arsenide photo-cathode, which yield a highly polarized electron beam. However, the beam's emittance might well be improved using a Superconducting RF electron gun, which delivers beams of higher brightness than DC guns does, because the field gradient at the cathode is higher. SRF guns with metal cathodes and CsTe cathodes have been tested successfully. To produce polarized electrons, a Gallium-Arsenide photo-cathode must be used: an experiment to do so in a superconducting RF gun is under way at BNL. Since the cathode will be normal conducting, the problem about the heat load stemming from the cathode arises. We present our measurements of the electrical resistance of GaAs at cryogenic temperatures, a prediction of the heat load and the verification by measuring the quality factor of the gun with and without cathode.

  13. Characterization of the CEBAF 100 kV DC GaAs Photoelectron Gun Vacuum System

    SciTech Connect (OSTI)

    M.L. Stutzman; P. Adderley; J. Brittian; J. Clark; J. Grames; J. Hansknecht; G.R. Myneni; M. Poelker

    2007-05-01

    A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower part of the UHV range. Measured NEG pump speed is high at pressures above 5×10^?11 Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers.

  14. Thermal influence on charge carrier transport in solar cells based on GaAs PN junctions

    SciTech Connect (OSTI)

    Osses-Márquez, Juan; Calderón-Muñoz, Williams R.

    2014-10-21

    The electron and hole one-dimensional transport in a solar cell based on a Gallium Arsenide (GaAs) PN junction and its dependency with electron and lattice temperatures are studied here. Electrons and heat transport are treated on an equal footing, and a cell operating at high temperatures using concentrators is considered. The equations of a two-temperature hydrodynamic model are written in terms of asymptotic expansions for the dependent variables with the electron Reynolds number as a perturbation parameter. The dependency of the electron and hole densities through the junction with the temperature is analyzed solving the steady-state model at low Reynolds numbers. Lattice temperature distribution throughout the device is obtained considering the change of kinetic energy of electrons due to interactions with the lattice and heat absorbed from sunlight. In terms of performance, higher values of power output are obtained with low lattice temperature and hot energy carriers. This modeling contributes to improve the design of heat exchange devices and thermal management strategies in photovoltaic technologies.

  15. Radiation damage to neutron and proton irradiated GaAs particle detectors

    E-Print Network [OSTI]

    M. Rogalla; Th. Eich; N. Evans; S. Joost; M. Kienzle; R. Geppert; R. Goeppert; R. Irsigler; J. Ludwig; K. Runge; Th. Schmid

    1997-04-04

    The radiation damage in 200 um thick Schottky diodes made on semi-insulating (SI) undoped GaAs Liquid Encapsulated Czochralski (LEC) bulk material with resistivities between 0.4 and 8.9*10E7 Ohm*cm were studied using alpha-spectroscopy, signal response to minimum ionising particles (MIP), I-V and CV-measurements. The results have been analysed to investigate the influence of the substrate resistivity on the detector performance after neutron and proton irradiation. The leakage current density, signal response to alpha-particles and MIPs show a strong dependence on the resistivity before and after irradiation. An observed decrease of the electron mean free drift length before and after irradiation with increasing substrate resistivity can be explained by a model involving the different ionisation ratios of defects, which are introduced by the irradiation. Comparison of the radiation damage due to neutrons and protons gives a hardness factor of 7+-0.9 for 24 GeV/c protons. The best detectors show a response to MIPs of 5250 e- at 200 V reverse bias after a irradiation level of 2*10E14 p/cm^2.

  16. High-power, mid-infrared, picosecond pulses generated by compression of a CO2 laser beat-wave in GaAs

    E-Print Network [OSTI]

    Pigeon, J J; Joshi, C

    2015-01-01

    We report on the generation of a train of ~ 2 ps, 10 um laser pulses via multiple four-wave mixing and compression of an infrared laser beat-wave propagating in the negative group velocity dispersion region of bulk GaAs and a combination of GaAs and NaCl. The use of a 200 ps, 106 GHz beat-wave, produced by combining laser pulses amplified on the 10P(20) and 10P(16) transition of a CO2 laser, provides a novel method for generating high-power, picosecond, mid-IR laser pulses at a high repetition rate. By using 165 and 882 GHz beat-waves we show that cascaded phase-mismatched difference frequency generation plays a significant role in the four-wave mixing process in GaAs.

  17. Ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer

    SciTech Connect (OSTI)

    Yang, Weiquan; Becker, Jacob; Liu, Shi; Kuo, Ying-Shen; Li, Jing-Jing; Zhang, Yong-Hang; Landini, Barbara; Campman, Ken

    2014-05-28

    This paper reports the proposal, design, and demonstration of ultra-thin GaAs single-junction solar cells integrated with a reflective back scattering layer to optimize light management and minimize non-radiative recombination. According to our recently developed semi-analytical model, this design offers one of the highest potential achievable efficiencies for GaAs solar cells possessing typical non-radiative recombination rates found among commercially available III-V arsenide and phosphide materials. The structure of the demonstrated solar cells consists of an In{sub 0.49}Ga{sub 0.51}P/GaAs/In{sub 0.49}Ga{sub 0.51}P double-heterostructure PN junction with an ultra-thin 300?nm thick GaAs absorber, combined with a 5??m thick Al{sub 0.52}In{sub 0.48}P layer with a textured as-grown surface coated with Au used as a reflective back scattering layer. The final devices were fabricated using a substrate-removal and flip-chip bonding process. Solar cells with a top metal contact coverage of 9.7%, and a MgF{sub 2}/ZnS anti-reflective coating demonstrated open-circuit voltages (V{sub oc}) up to 1.00?V, short-circuit current densities (J{sub sc}) up to 24.5?mA/cm{sup 2}, and power conversion efficiencies up to 19.1%; demonstrating the feasibility of this design approach. If a commonly used 2% metal grid coverage is assumed, the anticipated J{sub sc} and conversion efficiency of these devices are expected to reach 26.6?mA/cm{sup 2} and 20.7%, respectively.

  18. Multi-junction, monolithic solar cell using low-band-gap materials lattice matched to GaAs or Ge

    DOE Patents [OSTI]

    Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO); Friedman, Daniel J. (Lakewood, CO)

    2001-01-01

    A multi-junction, monolithic, photovoltaic solar cell device is provided for converting solar radiation to photocurrent and photovoltage with improved efficiency. The solar cell device comprises a plurality of semiconductor cells, i.e., active p/n junctions, connected in tandem and deposited on a substrate fabricated from GaAs or Ge. To increase efficiency, each semiconductor cell is fabricated from a crystalline material with a lattice constant substantially equivalent to the lattice constant of the substrate material. Additionally, the semiconductor cells are selected with appropriate band gaps to efficiently create photovoltage from a larger portion of the solar spectrum. In this regard, one semiconductor cell in each embodiment of the solar cell device has a band gap between that of Ge and GaAs. To achieve desired band gaps and lattice constants, the semiconductor cells may be fabricated from a number of materials including Ge, GaInP, GaAs, GaInAsP, GaInAsN, GaAsGe, BGaInAs, (GaAs)Ge, CuInSSe, CuAsSSe, and GaInAsNP. To further increase efficiency, the thickness of each semiconductor cell is controlled to match the photocurrent generated in each cell. To facilitate photocurrent flow, a plurality of tunnel junctions of low-resistivity material are included between each adjacent semiconductor cell. The conductivity or direction of photocurrent in the solar cell device may be selected by controlling the specific p-type or n-type characteristics for each active junction.

  19. Local Structures and Interface Morphology of InGaAsN Thin Films Grown on GaAs

    SciTech Connect (OSTI)

    Allerman, A.A.; Chen, J.G.; Geisz, J.F.; Huang, S.; Hulbert, S.L.; Jones, E.D.; Kao, Y.H.; Kurtz, S.; Kurtz, S.R.; Olson, J.M.; Soo, Y.L.

    1999-02-23

    The compound semiconductor system InGaAsN exhibits many intriguing properties which are particularly useful for the development of innovative high efficiency thin film solar cells and long wavelength lasers. The bandgap in these semiconductors can be varied by controlling the content of N and In and the thin films can yet be lattice-matched to GaAs. In the present work, x-ray absorption fine structure (XAFS) and grazing incidence x-ray scattering (GIXS) techniques have been employed to probe the local environment surrounding both N and In atoms as well as the interface morphology of InGaAsN thin films epitaxially grown on GaAs. The soft x-ray XAFS results around nitrogen K-edge reveal that N is in the sp{sup 3} hybridized bonding configuration in InGaAsN and GaAsN, suggesting that N impurities most likely substitute for As sites in these two compounds. The results of In K-edge XAFS suggest a possible trend of a slightly larger coordination number of As nearest neighbors around In atoms in InGaAsN samples with a narrower bandgap whereas the In-As interatomic distance remains practically the same as in InAs within the experimental uncertainties. These results combined suggest that N-substitution of the As sites plays an important role of bandgap-narrowing while in the meantime counteracting the compressive strain caused by In-doping. Grazing incidence x-ray scattering (GIXS) experiments verify that InGaAsN thin films can indeed form very smooth interfaces with GaAs yielding an average interfacial roughness of 5-20{angstrom}.

  20. Below gap optical absorption in GaAs driven by intense, single-cycle coherent transition radiation

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

    Goodfellow, J.; Fuchs, M.; Daranciang, D.; Ghimire, S.; Chen, F.; Loos, H.; Reis, D. A.; Fisher, A. S.; Lindenberg, A. M.

    2014-01-01

    Single-cycle terahertz fields generated by coherent transition radiation from a relativistic electron beam are used to study the high field optical response of single crystal GaAs. Large amplitude changes in the sub-band-gap optical absorption are induced and probed dynamically by measuring the absorption of a broad-band optical beam generated by transition radiation from the same electron bunch, providing an absolutely synchronized pump and probe geometry. This modification of the optical properties is consistent with strong-field-induced electroabsorption. These processes are pertinent to a wide range of nonlinear terahertz-driven light-matter interactions anticipated at accelerator-based sources.

  1. Highly polarized emission in spin resolved photoelectron spectroscopy of alpha-Fe(001)/GaAs(001)

    SciTech Connect (OSTI)

    Tobin, James; Yu, Sung Woo; Morton, Simon; Waddill, George; Thompson, Jamie; Neal, James; Spangenberg, Matthais; Shen, T.H.

    2009-05-19

    Highly spin-polarized sources of electrons, Integrated into device design, remain of great interest to the spintronic and magneto-electronic device community Here, the growth of Fe upon GaAs(001) has been studied with photoelectron spectroscopy (PES), including Spin Resolved PES. Despite evidence of atomic level disorder such as intermixing, an over-layer with the spectroscopic signature of alpha-Fe(001), with a bcc real space ordering, Is obtained The results will be discussed in light of the possibility of using such films as a spin-polarized source in device applications.

  2. The Influence of High-Energy Lithium Ion Irradiation on Electrical Characteristics of Silicon and GaAs Solar Cells

    E-Print Network [OSTI]

    B. Jayashree; Ramani; M. C. Radhakrishna; Anil Agrawal; Saif Ahmad Khan; A. Meulenberg

    2006-10-22

    Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models.

  3. Chirped-pulse manipulated carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs

    SciTech Connect (OSTI)

    Lee, Chao-Kuei, E-mail: chuckcklee@yahoo.com [Department of Photonics, National Sun-Yat-Sen University, Kaohsiung 80400, Taiwan (China); Lin, Yuan-Yao [Department of Electrical Engineering, Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30010, Taiwan (China); Lin, Sung-Hui [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lin, Gong-Ru [Department of Electrical Engineering, Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Roosevelt Road, Sec. 4, Taipei 10617, Taiwan (China); Pan, Ci-Ling [Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Physics, National Tsing Hwa University, Hsinchu 30010, Taiwan (China)

    2014-04-28

    Chirped pulse controlled carrier dynamics in low-temperature molecular-beam-epitaxy grown GaAs are investigated by degenerate pump-probe technique. Varying the chirped condition of excited pulse from negative to positive increases the carrier relaxation time so as to modify the dispersion and reshape current pulse in time domain. The spectral dependence of carrier dynamics is analytically derived and explained by Shockley-Read Hall model. This observation enables the new feasibility of controlling carrier dynamics in ultrafast optical devices via the chirped pulse excitations.

  4. Effect of Bi isovalent dopants on the formation of homogeneous coherently strained InAs quantum dots in GaAs matrices

    SciTech Connect (OSTI)

    Peleshchak, R. M.; Guba, S. K.; Kuzyk, O. V.; Kurilo, I. V.; Dankiv, O. O.

    2013-03-15

    The distribution of hydrostatic strains in Bi{sup 3+}-doped InAs quantum dots embedded in a GaAs matrix are calculated in the context of the deformation-potential model. The dependences of strains in the material of spherical InAs quantum dots with substitutional (Bi {yields} As) and interstitial (Bi) impurities on the quantum-dot size are derived. The qualitative correlation of the model with the experiment is discussed. The data on the effect of doping on the morphology of self-assembled InAs:Bi quantum dots in a GaAs matrix are obtained.

  5. Interface composition between Fe{sub 3}O{sub 4} nanoparticles and GaAs for spintronic applications

    SciTech Connect (OSTI)

    Hihath, Sahar; Kiehl, Richard A.; Benthem, Klaus van

    2014-08-28

    Recent interest in spintronic applications has necessitated the study of magnetic materials in contact with semiconductor substrates; importantly, the structure and composition of these interfaces can influence both device functionality and the magnetic properties. Nanoscale ferromagnet/semiconductor structures are of particular interest. In this study, the interface structure between a monolayer of ferromagnetic magnetite (Fe{sub 3}O{sub 4}) nanoparticles and a GaAs substrate was studied using cross-sectional transmission electron microscopy techniques. It was found that a continuous amorphous oxide interface layer separates the nanoparticles from the GaAs substrate, and that iron diffused into the interface layer forming a compositional gradient. Electron energy-loss near-edge fine structures of the O K absorption edge revealed that the amorphous oxide is composed of ?-Fe{sub 2}O{sub 3} directly underneath the Fe{sub 3}O{sub 4} nanoparticles, followed by a solid solution of Ga{sub 2}O{sub 3} and FeO and mostly Ga{sub 2}O{sub 3} when approaching the buckled oxide/substrate interface. Real-space density functional theory calculations of the dynamical form factor confirmed the experimental observations. The implication of the findings on the optimization of these structures for spin injection is discussed.

  6. First-principles studies on molecular beam epitaxy growth of GaAs1-xBix

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

    Luo, Guangfu; Yang, Shujiang; Li, Jincheng; Arjmand, Mehrdad; Szlufarska, Izabela; Brown, April S.; Kuech, Thomas F.; Morgan, Dane

    2015-07-14

    We investigate the molecular beam epitaxy (MBE) growth of GaAs1-xBix film using density functional theory with spin-orbit coupling to understand the growth of this film, especially the mechanisms of Bi incorporation. We study the stable adsorption structures and kinetics of the incident molecules (As? molecule, Ga atom, Bi atom, and Bi? molecule) on the (2 x 1)-Gasub||Bi surface and a proposed q(1 x 1)-Gasub||AsAs surface has a quasi-(1 x 1) As layer above the Ga-terminated GaAs substrate and a randomly oriented As dimer layer on top. We obtain the desorption and diffusion barriers of the adsorbed molecules and also themore »reaction barriers of three key processes related to Bi evolution, namely, Bi incorporation, As/Bi exchange, and Bi clustering. The results help explain the experimentally observed dependence of Bi incorporation on the As/Ga ratio and growth temperature. Furthermore, we find that As? exchange with Bi of the (2 x 1)-Gasub||Bi surface is a key step controlling the kinetics of the Bi incorporation. Finally, we explore two possible methods to enhance the Bi incorporation, namely, replacing the MBE growth mode from codeposition of all fluxes with a sequential deposition of fluxes and applying asymmetric in-plane strain to the substrate.« less

  7. Condensation mechanisms of an arsenic-rich vapor on GaAs (001) surfaces D. A. Murdick* and H. N. G. Wadley

    E-Print Network [OSTI]

    Wadley, Haydn

    that are much greater than unity.6,7 Oscillations in reflection high-energy electron dif- fraction RHEED patterns and scanning tunneling micros- copy STM have identified the range of processing condi- tions of excess arsenic that can be trapped in the as-grown GaAs lattice increases as the temperature decreases.9

  8. Ab initio cluster calculations of hydrogenated GaAs,,001... surfaces Chemical Engineering Department, University of California, Los Angeles, California 90095-1592

    E-Print Network [OSTI]

    Li, Lian

    Ab initio cluster calculations of hydrogenated GaAs,,001... surfaces Q. Fu Chemical Engineering Engineering Department, University of California, Los Angeles, California 90095-1592 Received 11 November 1999 hydrides. The latter species occur in isolated or coupled structures involving two or three Ga atoms. I

  9. Hybrid Fe3O4/GaAs,,100... structure for spintronics Y. X. Lu, J. S. Claydon, E. Ahmad, and Y. B. Xua

    E-Print Network [OSTI]

    Xu, Yongbing

    Hybrid Fe3O4/GaAs,,100... structure for spintronics Y. X. Lu, J. S. Claydon, E. Ahmad, and Y. B. Xua Spintronics Laboratory, Department of Electronics, University of York, York, YO10 5DD, United for spintronic application. © 2005 American Institute of Physics. DOI: 10.1063/1.1857432 I. INTRODUCTION Magnetic

  10. GaAs nanowire array solar cells with axial p-i-n Maoqing Yao, Ningfeng Huang, Sen Cong, Chun-Yung Chi, M. Ashkan Seyedi,

    E-Print Network [OSTI]

    Zhou, Chongwu

    interconnecting scheme. Figure S1. Multi-junction solar cells. (a) Multi-junction solar cells consist of materials1 GaAs nanowire array solar cells with axial p-i-n junctions Maoqing Yao, Ningfeng Huang, Sen CongH3 are 7.56×10-7 atm and 2.14×10-4 atm. Solar cells fabrication. Transparent insulating polymer BCB

  11. Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs Sonia Buckley, Marina Radulaski, Klaus Biermann, and Jelena Vukovi

    E-Print Network [OSTI]

    Vuckovic, Jelena

    . III-V semi- conductors also allow integration of active gain media such as quantum dots or quantum-V semiconductors such as GaAs, GaP, and InP, as these materi- als have a very high second order nonlinearity

  12. Towards low-cost high-efficiency GaAs photovoltaics and photoelectrodes grown via vapor transport from a solid source

    SciTech Connect (OSTI)

    Boucher, Jason; Ritenour, Andrew; Boettcher, Shannon W.

    2013-04-29

    Towards low-cost high-efficiency GaAs photovoltaics and photoelectrodes grown via vapor transport from a solid source GaAs is an attractive material for thin-film photovoltaic applications, but is not widely used for terrestrial power generation due to the high cost of metal-organic chemical vapor deposition (MOCVD) techniques typically used for growth. Close space vapor transport is an alternative that allows for rapid growth rates of III-V materials, and does not rely on the toxic and pyrophoric precursors used in MOCVD. We characterize CSVT films of GaAs using photoelectrochemical current-voltage and quantum efficiency measurements. Hole diffusion lengths which exceed 1.5 um are extracted from internal quantum efficiency measurements using the Gartner model. Device physics simulations suggest that solar cells based on these films could reach efficiencies exceeding 24 %. To reach this goal, a more complete understanding of the electrical properties and characterization of defects will be necessary, including measurements on complete solid-state devices. Doping of films is achieved by using source material containing the desired impurity (e.g., Te or Zn). We discuss strategies for growing III-V materials on inexpensive substrates that are not lattice-matched to GaAs.

  13. In situ metal-organic chemical vapor deposition atomic-layer deposition of aluminum oxide on GaAs using trimethyaluminum

    E-Print Network [OSTI]

    In situ metal-organic chemical vapor deposition atomic-layer deposition of aluminum oxide on Ga 26 June 2008; published online 21 July 2008 In situ atomic-layer deposition ALD of Al2O3 on p­4 Recently, many ex situ methods such as atomic-layer deposition ALD of high-k on GaAs have achieved success

  14. Si3N4 on GaAs by direct electron cyclotron resonance plasma assisted nitridation of Si layer in Si/GaAs structure

    E-Print Network [OSTI]

    Rockett, Angus

    from XPS as a function of photoelectron takeoff angle, initially increased rapidly with nitridation either from the higher temperature or from nitridation of all of the Si, leaving the Si3N4 in direct contact with the GaAs. © 1998 American Vacuum Society. S0734-211X 98 00302-3 I. INTRODUCTION Ga

  15. Magnetic anisotropies in epitaxial Fe{sub 3}O{sub 4}/GaAs(100) patterned structures

    SciTech Connect (OSTI)

    Zhang, W. Zhang, D.; Yuan, S. J.; Huang, Z. C.; Zhai, Y.; Wong, P. K. J.; Wu, J.; Xu, Y. B.

    2014-10-15

    Previous studies on epitaxial Fe{sub 3}O{sub 4} rings in the context of spin-transfer torque effect have revealed complicated and undesirable domain structures, attributed to the intrinsic fourfold magnetocrystalline anisotropy in the ferrite. In this Letter, we report a viable solution to this problem, utilizing a 6-nm-thick epitaxial Fe{sub 3}O{sub 4} thin film on GaAs(100), where the fourfold magnetocrystalline anisotropy is negligible. We demonstrate that in the Fe{sub 3}O{sub 4} planar wires patterned from our thin film, such a unique magnetic anisotropy system has been preserved, and relatively simple magnetic domain configurations compared to those previous reports can be obtained.

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

    SciTech Connect (OSTI)

    Estacio, Elmer; Pham, Minh Hong; Takatori, Satoru; Cadatal-Raduban, Marilou; Nakazato, Tomoharu; Shimizu, Toshihiko; Sarukura, Nobuhiko; Somintac, Armando; Defensor, Michael; Awitan, Fritz Christian B.; Jaculbia, Rafael B.; Salvador, Arnel; Garcia, Alipio

    2009-06-08

    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.

  17. Metamorphic approach to single quantum dot emission at 1.55 {mu}m on GaAs substrate

    SciTech Connect (OSTI)

    Semenova, E. S.; Hostein, R.; Patriarche, G.; Mauguin, O.; Largeau, L.; Robert-Philip, I.; Beveratos, A.; Lemaitre, A.

    2008-05-15

    We report on the fabrication and the characterization of InAs quantum dots (QDs) embedded in an indium rich In{sub 0.42}Ga{sub 0.58}As metamorphic matrix grown on a GaAs substrate. Growth conditions were chosen so as to minimize the number of threading dislocations and other defects produced during the plastic relaxation. Sharp and bright lines, originating from the emission of a few isolated single quantum dots, were observed in microphotoluminescence around 1.55 {mu}m at 5 K. They exhibit, in particular, a characteristic exciton/biexciton behavior. These QDs could offer an interesting alternative to other approaches as InAs/InP QDs for the realization of single photon emitters at telecom wavelengths.

  18. Point contact Andreev spectroscopy of epitaxial Co{sub 2}FeSi Heusler alloys on GaAs (001)

    SciTech Connect (OSTI)

    Lehmann, Hauke; Merkt, Ulrich; Meier, Guido [Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Universitaet Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany); Scholtyssek, Jan M. [Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Universitaet Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany); Institut fuer Elektrische Messtechnik und Grundlagen der Elektrotechnik, Technische Universitaet Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig (Germany); Herrmann, Claudia; Herfort, Jens [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2011-09-15

    The predicted half-metallicity of Co{sub 2}FeSi in combination with its high Curie temperature of above 980 K makes this Heusler alloy interesting for spinelectronics. Thin Co{sub 2}FeSi films are grown by molecular-beam epitaxy on GaAs (001) with a close lattice match. We present a study of point-contact measurements on different films, varying in thickness between 18 nm and 48 nm and in substrate temperature during deposition between 100 deg. C and 300 deg. C. Transport spin polarizations at the Fermi level are determined from differential conductance curves obtained by point-contact Andreev-reflection spectroscopy. A maximum transport spin polarization of about 60% is measured for a 18 nm thin Co{sub 2}FeSi film grown at 200 deg. C.

  19. Ultrahigh Bandwidth Spin Noise Spectroscopy: Detection of Large g-Factor Fluctuations in Highly n-Doped GaAs

    E-Print Network [OSTI]

    Fabian Berski; Hendrik Kuhn; Jan G. Lonnemann; Jens Hübner; Michael Oestreich

    2012-06-30

    We advance all optical spin noise spectroscopy (SNS) in semiconductors to detection bandwidths of several hundred gigahertz by employing an ingenious scheme of pulse trains from ultrafast laser oscillators as an optical probe. The ultrafast SNS technique avoids the need for optical pumping and enables nearly perturbation free measurements of extremely short spin dephasing times. We employ the technique to highly n-doped bulk GaAs where magnetic field dependent measurements show unexpected large g-factor fluctuations. Calculations suggest that such large g-factor fluctuations do not necessarily result from extrinsic sample variations but are intrinsically present in every doped semiconductor due to the stochastic nature of the dopant distribution.

  20. Monolithically interconnected GaAs solar cells: A new interconnection technology for high voltage solar cell output

    SciTech Connect (OSTI)

    Dinetta, L.C.; Hannon, M.H.

    1995-10-01

    Photovoltaic linear concentrator arrays can benefit from high performance solar cell technologies being developed at AstroPower. Specifically, these are the integration of thin GaAs solar cell and epitaxial lateral overgrowth technologies with the application of monolithically interconnected solar cell (MISC) techniques. This MISC array has several advantages which make it ideal for space concentrator systems. These are high system voltage, reliable low cost monolithically formed interconnections, design flexibility, costs that are independent of array voltage, and low power loss from shorts, opens, and impact damage. This concentrator solar cell will incorporate the benefits of light trapping by growing the device active layers over a low-cost, simple, PECVD deposited silicon/silicon dioxide Bragg reflector. The high voltage-low current output results in minimal 12R losses while properly designing the device allows for minimal shading and resistance losses. It is possible to obtain open circuit voltages as high as 67 volts/cm of solar cell length with existing technology. The projected power density for the high performance device is 5 kW/m for an AMO efficiency of 26% at 1 5X. Concentrator solar cell arrays are necessary to meet the power requirements of specific mission platforms and can supply high voltage power for electric propulsion systems. It is anticipated that the high efficiency, GaAs monolithically interconnected linear concentrator solar cell array will enjoy widespread application for space based solar power needs. Additional applications include remote man-portable or ultra-light unmanned air vehicle (UAV) power supplies where high power per area, high radiation hardness and a high bus voltage or low bus current are important. The monolithic approach has a number of inherent advantages, including reduced cost per interconnect and increased reliability of array connections. There is also a high potential for a large number of consumer products.

  1. Enhanced binding energy of manganese acceptors close to the GaAs(110) surface J. K. Garleff,1,* A. P. Wijnheijmer,1 A. Yu. Silov,1 J. van Bree,1 W. Van Roy,2 J.-M. Tang,3

    E-Print Network [OSTI]

    Flatte, Michael E.

    3 Department of Physics, University of New Hampshire, Durham, New Hampshire 03824, USA 4Optical and the electric field but also due to the broken symmetry in the buckled relaxation at the GaAs 110 surface.10

  2. Investigating the chemical and morphological evolution of GaAs capped InAs/InP quantum dots emitting at 1.5 mm using aberration-corrected

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    s t r a c t The emission wavelength of InAs quantum dots grown on InP has been shown to shiftInvestigating the chemical and morphological evolution of GaAs capped InAs/InP quantum dots microscopy A3. Metalorganic vapour-phase epitaxy A3. Quantum dots B2. Semiconducting III/V materials a b

  3. A 77 GHz Transceiver for Automotive Radar System Using a120nm In AlAs/In GaAs Metamorphic HEMTs

    E-Print Network [OSTI]

    Kwon, Youngwoo

    A 77 GHz Transceiver for Automotive Radar System Using a120nm 0.4 0.35 In AlAs/In GaAs Metamorphic-mail:ykwon@snu.ac.kr) Abstract -- In this work, we demonstrate a compact 77GHz single-chip transceiver for an automotive radar at the transmitter and a 5dB conversion gain at the receiver. Index Terms -- Automotive radar, 77GHz, MHEMT, MMIC

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

    E-Print Network [OSTI]

    Haller, Gary L.

    solar cells are triple-junction concentrator devices, with each junction efficiently col- lecting subcell in a multijunction de- vice. GaAs0.66 P0.34 single-junction solar cells with Eg = 1.83 eV were56 IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 1, JANUARY 2012 Metamorphic GaAsP and InGaP Solar

  5. Atomic and electronic structures of SrTiO3/GaAs heterointerfaces: An 80-kV atomic-resolution electron energy-loss spectroscopy study

    SciTech Connect (OSTI)

    Qiao, Q.; Klie, Robert F; Ogut, Serdar; Idrobo Tapia, Juan C

    2012-01-01

    We have examined the atomic and electronic structures of epitaxially grown, ultrathin SrTiO{sub 3} (100) films on GaAs (001) using 80-kV aberration-corrected atomic-resolution Z-contrast imaging and electron energy-loss spectroscopy (EELS) to develop a fundamental understanding of the interfacial structure-property relationships. We find that the interface is atomically abrupt and no surface reconstruction of the GaAs (001) surface is observed. Using atomic-column resolved EELS, we examine the oxygen vacancy and Ti concentrations in the SrTiO{sub 3} film and across the heterointerface. We show that Ti diffuses into the first few monolayers of GaAs. Using a combination of EELS and first-principles calculations, we present evidence for the formation of As oxides at the interface depending on the thin-film growth conditions. These findings are used to explain the differences in the transport behavior of the films.

  6. 20% (AM1.5) efficiency GaAs solar cells on sub-mm grain-size poly-Ge and its transition to low-cost substrates

    SciTech Connect (OSTI)

    Venkatasubramanian, R.; O`Quinn, B.C.; Siivola, E.; Keyes, B.; Ahrenkiel, R.

    1997-12-31

    Some of the key material and device issues related to the development of GaAs solar cells on poly-Ge substrates, including the dark-current reduction mechanism with an undoped spacer at the p{sup +}-n depletion layer, are discussed. Device-structure optimization studies that have led the authors to achieve an AM1.5 efficiency of {approximately}20% for a 4-cm{sup 2}-area GaAs cell on sub-mm grain-size poly-Ge and an efficiency of {approximately}21% for a 0.25-cm{sup 2}-area cell are presented. This successful demonstration of high-efficiency GaAs cells on sub-mm grain-size poly-Ge substrates have motivated us to consider the development of high-quality GaAs materials on significantly lower-cost substrates such as glass and moly foils. To date, the authors have achieved a best minority-carrier lifetime of 0.41 nsec in an n-GaAs thin-film on moly. The role of Group-VI dopant in the possible passivation of grain-boundaries in poly-GaAs is discussed. Development of PV-quality GaAs material, with minority-carrier lifetime of 1 to 2 nsec, on los-cost moly foils can significantly impact both the terrestrial and the space PV applications.

  7. InGaAsN Solar Cells with 1.0eV Bandgap, Lattice Matched to GaAs

    SciTech Connect (OSTI)

    Allerman, A.A.; Banas, J.J.; Gee, J.M.; Hammons, B.E.; Jones, E.D.; Kurtz, S.R.

    1998-11-24

    The design, growth by metal-organic chemical vapor deposition, and processing of an In{sub 0.07}Ga{sub 0.93}As{sub 0.98}N{sub 0.02} solar Al, with 1.0 ev bandgap, lattice matched to GaAs is described. The hole diffusion length in annealed, n-type InGaAsN is 0.6-0.8 pm, and solar cell internal quantum efficiencies > 70% arc obwined. Optical studies indicate that defects or impurities, from InGAsN doping and nitrogen incorporation, limit solar cell performance.

  8. Final Technical Progress Report: High-Efficiency Low-Cost Thin-Film GaAs Photovoltaic Module Development Program; July 14, 2010 - January 13, 2012

    SciTech Connect (OSTI)

    Mattos, L.

    2012-03-01

    This is the final technical progress report of the High-Efficiency Low-Cost Thin-Film GaAs Photovoltaic Module Development Program. Alta Devices has successfully completed all milestones and deliverables established as part of the NREL PV incubator program. During the 18 months of this program, Alta has proven all key processes required to commercialize its solar module product. The incubator focus was on back end process steps directed at conversion of Alta's high quality solar film into high efficiency 1-sun PV modules. This report describes all program deliverables and the work behind each accomplishment.

  9. Localization-delocalization transition of electrons at the percolation threshold of semiconductor GaAs1–xNx alloys: The appearance of a mobility edge

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

    Alberi, K.; Fluegel, B.; Beaton, D. A.; Ptak, A. J.; Mascarenhas, A.

    2012-07-09

    Electrons in semiconductor alloys have generally been described in terms of Bloch states that evolve from constructive interference of electron waves scattering from perfectly periodic potentials, despite the loss of structural periodicity that occurs on alloying. Using the semiconductor alloy GaAs??xNx as a prototype, we demonstrate a localized to delocalized transition of the electronic states at a percolation threshold, the emergence of a mobility edge, and the onset of an abrupt perturbation to the host GaAs electronic structure, shedding light on the evolution of electronic structure in these abnormal alloys.

  10. Controllable growth and optical properties of InP and InP/InAs nanostructures on the sidewalls of GaAs nanowires

    SciTech Connect (OSTI)

    Yan, Xin; Zhang, Xia Li, Junshuai; Cui, Jiangong; Ren, Xiaomin

    2014-12-07

    The growth and optical properties of InP and InP/InAs nanostructures on GaAs nanowires are investigated. InP quantum well and quantum dots (QDs) are formed on the sidewalls of GaAs nanowires successively with increasing the deposition time of InP. The GaAs/InP nanowire heterostructure exhibits a type-II band alignment. The wavelength of the InP quantum well is in the range of 857–892?nm at 77?K, which means that the quantum well is nearly fully strained. The InP quantum dot, which has a bow-shaped cross section, exhibits dislocation-free pure zinc blende structure. Stranski-Krastanow InAs quantum dots are subsequently formed on the GaAs/InP nanowire core-shell structure. The InAs quantum dots are distributed over the middle part of the nanowire, indicating that the In atoms contributing to the quantum dots mainly come from the vapor rather than the substrate. The longest emission wavelength obtained from the InAs QDs is 1039?nm at 77?K. The linewidth is as narrow as 46.3?meV, which is much narrower than those on planar InP substrates and wurtzite InP nanowires, suggesting high-crystal-quality, phase-purity, and size-uniformity of quantum dots.

  11. 1EV GaN[subscript x]As[subscript 1-x-y]Sb[subscript y] material for lattice-matched III-V solar cell implementation on GaAs and Ge

    E-Print Network [OSTI]

    Yoon, Soon Fatt

    The effect of different arsenic species (As[subscript 2] or As[subscript 4]) on the quality of molecular beam epitaxy (MBE) grown GaNAsSb materials (samples A and B) and GaAs/ GaNAsSb/GaAs p+n-n+ devices (samples C and D) ...

  12. GaAs Nanowire Array Solar Cells with Axial p-i-n Junctions Maoqing Yao, Ningfeng Huang, Sen Cong, Chun-Yung Chi, M. Ashkan Seyedi, Yen-Ting Lin, Yu Cao,

    E-Print Network [OSTI]

    Zhou, Chongwu

    into multijunction solar cells. Here, we report GaAs nanowire solar cells with axial p-i-n junctions that achieve 7-Queisser efficiency limit is to use multijunction solar cells containing several p-n junctions in series.22-26 Each multijunction solar cells consist of sequentially stacked thin films. The lattice constants of the materials

  13. Gypsum, Colorado: 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 QA:QAsource History View New PagesSustainableGlynn County,SolarFERC HydroelectricGuofu BioenergyNewGwitchyaa

  14. Spatially resolved study of polarized micro-photoluminescence spectroscopy on single GaAs nanowires with mixed zincblende and wurtzite phases

    SciTech Connect (OSTI)

    Mukherjee, Amlan; Ghosh, Sandip; Breuer, Steffen; Jahn, Uwe; Geelhaar, Lutz; Grahn, Holger T.

    2015-02-07

    Localized and polarized photoluminescence spectra are observed in single GaAs nanowires with mixed zincblende and wurtzite phases, grown using molecular beam epitaxy. For low excitation intensities, the photoluminescence emission exhibits narrow spectral features predominantly polarized perpendicular to the nanowire axis. For high excitation intensities, the photoluminescence spectra transform into dominant broadened features, which exhibit different peak energies and polarization properties. The strongly polarized emission at high excitation intensities is identified as being due to a spatially direct transition in wurtzite sections of the nanowires. The analysis, including band structure calculations suggests that carriers in the wurtzite sections diffuse into regions where the average low-temperature peak emission energy and crystal field parameter are 1.535?eV and 20?meV, respectively.

  15. InGaAs/GaAsP strain balanced multi-quantum wires grown on misoriented GaAs substrates for high efficiency solar cells

    SciTech Connect (OSTI)

    Alonso-Álvarez, D.; Thomas, T.; Führer, M.; Hylton, N. P.; Ekins-Daukes, N. J.; Lackner, D.; Philipps, S. P.; Bett, A. W.; Sodabanlu, H.; Fujii, H.; Watanabe, K.; Sugiyama, M.; Nasi, L.; Campanini, M.

    2014-08-25

    Quantum wires (QWRs) form naturally when growing strain balanced InGaAs/GaAsP multi-quantum wells (MQW) on GaAs [100] 6° misoriented substrates under the usual growth conditions. The presence of wires instead of wells could have several unexpected consequences for the performance of the MQW solar cells, both positive and negative, that need to be assessed to achieve high conversion efficiencies. In this letter, we study QWR properties from the point of view of their performance as solar cells by means of transmission electron microscopy, time resolved photoluminescence and external quantum efficiency (EQE) using polarised light. We find that these QWRs have longer lifetimes than nominally identical QWs grown on exact [100] GaAs substrates, of up to 1??s, at any level of illumination. We attribute this effect to an asymmetric carrier escape from the nanostructures leading to a strong 1D-photo-charging, keeping electrons confined along the wire and holes in the barriers. In principle, these extended lifetimes could be exploited to enhance carrier collection and reduce dark current losses. Light absorption by these QWRs is 1.6 times weaker than QWs, as revealed by EQE measurements, which emphasises the need for more layers of nanostructures or the use light trapping techniques. Contrary to what we expected, QWR show very low absorption anisotropy, only 3.5%, which was the main drawback a priori of this nanostructure. We attribute this to a reduced lateral confinement inside the wires. These results encourage further study and optimization of QWRs for high efficiency solar cells.

  16. Current flow and potential efficiency of solar cells based on GaAs and GaSb p-n junctions

    SciTech Connect (OSTI)

    Andreev, V. M.; Evstropov, V. V.; Kalinovsky, V. S. Lantratov, V. M.; Khvostikov, V. P.

    2009-05-15

    Dependence of the efficiency of single-junction and multijunction solar cells on the mechanisms of current flow in photoactive p-n junctions, specifically on the form of the dark current-voltage characteristic J-V, has been studied. The resistanceless J-V{sub j} characteristic (with the series resistance disregarded) of a multijunction solar cell has the same shape as the characteristic of a single-junction cell: both feature a set of exponential portions. This made it possible to develop a unified analytical method for calculating the efficiency of singlejunction and multijunction solar cells. The equation relating the efficiency to the photogenerated current at each portion of the J-V{sub j} characteristic is derived. For p-n junctions in GaAs and GaSb, the following characteristics were measured: the dark J-V characteristic, the dependence of the open-circuit voltage on the illumination intensity P-V{sub OC}, and the dependence of the luminescence intensity on the forward current L-J. Calculated dependences of potential efficiency (under idealized condition for equality to unity of external quantum yield) on the photogenerated current for single-junction GaAs and GaSb solar cells and a GaAs/GaSb tandem are plotted. The form of these dependences corresponds to the shape of J-V{sub j} characteristics: there are the diffusion- and recombination-related portions; in some cases, the tunneling-trapping portion is also observed. At low degrees of concentration of solar radiation (C < 10), an appreciable contribution to photogenerated current is made by recombination component. It is an increase in this component in the case of irradiation with 6.78-MeV protons or 1-MeV electrons that brings about a decrease in the efficiency of conversion of unconcentrated solar radiation.

  17. Seismic load-resisting capacity of plastered straw bale walls

    E-Print Network [OSTI]

    Hsiaw, Jennifer S. (Jennifer Sing-Yee)

    2010-01-01

    Straw bales have been incorporated into buildings for centuries, but only recently have they been explored in academic settings for their structural potential. Straw bale building is encountering a growing audience due to ...

  18. Unconstrained paving and plastering method for generating finite element meshes

    DOE Patents [OSTI]

    Staten, Matthew L. (Albuquerque, NM); Owen, Steven J. (Albuquerque, NM); Blacker, Teddy D. (Albuquerque, NM); Kerr, Robert (Albuquerque, NM)

    2010-03-02

    Computer software for and a method of generating a conformal all quadrilateral or hexahedral mesh comprising selecting an object with unmeshed boundaries and performing the following while unmeshed voids are larger than twice a desired element size and unrecognizable as either a midpoint subdividable or pave-and-sweepable polyhedra: selecting a front to advance; based on sizes of fronts and angles with adjacent fronts, determining which adjacent fronts should be advanced with the selected front; advancing the fronts; detecting proximities with other nearby fronts; resolving any found proximities; forming quadrilaterals or unconstrained columns of hexahedra where two layers cross; and establishing hexahedral elements where three layers cross.

  19. NMR relaxometry study of plaster mortar with polymer additives

    SciTech Connect (OSTI)

    Jumate, E.; Manea, D. [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania)] [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania); Moldovan, D.; Fechete, R. [Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca (Romania)] [Technical University of Cluj-Napoca, Department of Physics and Chemistry, 25 G. Baritiu Str., 400027, Cluj-Napoca (Romania)

    2013-11-13

    The cement mixed with water forms a plastic paste or slurry which stiffness in time and finally hardens into a resistant stone. The addition of sand aggregates, polymers (Walocel) and/or calcium carbonate will modify dramatically the final mortar mechanic and thermal properties. The hydration processes can be observed using the 1D NMR measurements of transverse T{sub 2} relaxation times distributions analysed by a Laplace inversion algorithm. These distributions were obtained for mortar pasta measured at 2 hours after preparation then at 3, 7 and 28 days after preparation. Multiple components are identified in the T{sub 2} distributions. These can be associated with the proton bounded chemical or physical to the mortar minerals characterized by a short T{sub 2} relaxation time and to water protons in pores with three different pore sizes as observed from SEM images. The evaporation process is faster in the first hours after preparation, while the mortar hydration (bonding of water molecules to mortar minerals) can be still observed after days or months from preparation. Finally, the mechanic resistance was correlated with the transverse T{sub 2} relaxation rates corresponding to the bound water.

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

    E-Print Network [OSTI]

    Wang, Deli

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

  1. Conversion of above- and below-bandgap photons via InAs quantum dot media embedded into GaAs solar cell

    SciTech Connect (OSTI)

    Sablon, K.; Little, J. [U.S. Army Research Laboratory, Adelphi, Maryland 20783 (United States); Vagidov, N. [Optoelectronic Nanodevices LLC, Amherst, New York 14226 (United States); Li, Y.; Mitin, V.; Sergeev, A. [EE Department, University at Buffalo—SUNY, Buffalo, New York 14260 (United States)

    2014-06-23

    Quantum dots (QDs) provide photovoltaic conversion of below-bandgap photons due to multistep electron transitions. QDs also increase conversion efficiency of the above-bandgap photons due to extraction of electrons from QDs via Coulomb interaction with hot electrons excited by high-energy photons. Nanoscale potential profile (potential barriers) and nanoscale band engineering (AlGaAs atomically thin barriers) allow for suppression of photoelectron capture to QDs. To study these kinetic effects and to distinguish them from the absorption enhancement due to light scattering on QDs, we investigate long, 3-?m base GaAs devices with various InAs QD media with 20 and 40 QD layers. Quantum efficiency measurements show that, at least at low doping, the multistep processes in QD media are strongly affected by the wetting layer (WL). The QD media with WLs provide substantial conversion of below-bandgap photons and for devices with 40 QD layers the short circuit current reaches 29.2?mA/cm{sup 2}. The QD media with band-engineered AlGaAs barriers and reduced wetting layers (RWL) enhance conversion of high-energy photons and decrease the relaxation (thermal) losses.

  2. Structural and band alignment properties of Al{sub 2}O{sub 3} on epitaxial Ge grown on (100), (110), and (111)A GaAs substrates by molecular beam epitaxy

    SciTech Connect (OSTI)

    Hudait, M. K.; Zhu, Y.; Maurya, D.; Priya, S.; Patra, P. K.; Ma, A. W. K.; Aphale, A.; Macwan, I.

    2013-04-07

    Structural and band alignment properties of atomic layer Al{sub 2}O{sub 3} oxide film deposited on crystallographically oriented epitaxial Ge grown in-situ on (100), (110), and (111)A GaAs substrates using two separate molecular beam epitaxy chambers were investigated using cross-sectional transmission microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). High-resolution triple axis x-ray measurement demonstrated pseudomorphic and high-quality Ge epitaxial layer on crystallographically oriented GaAs substrates. The cross-sectional TEM exhibited a sharp interface between the Ge epilayer and each orientation of the GaAs substrate as well as the Al{sub 2}O{sub 3} film and the Ge epilayer. The extracted valence band offset, {Delta}E{sub v}, values of Al{sub 2}O{sub 3} relative to (100), (110), and (111) Ge orientations using XPS measurement were 3.17 eV, 3.34 eV, and 3.10 eV, respectively. Using XPS data, variations in {Delta}E{sub v} related to the crystallographic orientation were {Delta}E{sub V}(110)Ge>{Delta}E{sub V}(100)Ge{>=}{Delta}E{sub V}(111)Ge and the conduction band offset, {Delta}E{sub c}, related to the crystallographic orientation was {Delta}E{sub c}(111)Ge>{Delta}E{sub c}(110)Ge>{Delta}E{sub c}(100)Ge using the measured {Delta}E{sub v}, bandgap of Al{sub 2}O{sub 3} in each orientation, and well-known Ge bandgap of 0.67 eV. These band offset parameters are important for future application of Ge-based p- and n-channel metal-oxide field-effect transistor design.

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

    SciTech Connect (OSTI)

    Ledentsov, N. N., E-mail: nikolay.ledentsov@v-i-systems.com; Shchukin, V. A. [VI Systems GmbH, Hardenbergstr. 7, Berlin D-10623 (Germany); Lyytikäinen, J.; Okhotnikov, O. [Optoelectronics Research Centre, Tampere University of Technology, Tampere FI-33720 (Finland); Shernyakov, Yu. M.; Payusov, A. S.; Gordeev, N. Yu.; Maximov, M. V. [A. F. Ioffe Physical Technical Institute of the Russian Academy of Sciences, Politekhnicheskaya 26, St. Petersburg 194021 (Russian Federation); Schlichting, S.; Nippert, F.; Hoffmann, A. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, Berlin D-10623 (Germany)

    2014-11-03

    We report on green (550–560?nm) electroluminescence (EL) from (Al{sub 0.5}Ga{sub 0.5}){sub 0.5}In{sub 0.5}P-(Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P double p-i-n heterostructures with monolayer-scale GaP insertions in the cladding layers and light-emitting diodes based thereupon. The structures are grown side-by-side on high-index and (100) GaAs substrates by molecular beam epitaxy. At moderate current densities (?500?A/cm{sup 2}), the EL intensity of the structures is comparable for all substrate orientations. Opposite to the (100)-grown strictures, the EL spectra of (211) and (311)-grown devices are shifted towards shorter wavelengths (?550?nm at room temperature). At high current densities (>1?kA/cm{sup 2}), a much higher EL intensity is achieved for the devices grown on high-index substrates. The integrated intensity of (311)-grown structures gradually saturates at current densities above 4?kA/cm{sup 2}, whereas no saturation is revealed for (211)-grown structures up to the current densities above 14?kA/cm{sup 2}. We attribute the effect to the surface orientation-dependent engineering of the GaP band structure, which prevents the escape of the nonequilibrium electrons into the indirect conduction band minima of the p-doped (Al{sub 0.8}Ga{sub 0.2}){sub 0.5}In{sub 0.5}P cladding layers.

  4. The current–voltage and capacitance–voltage characteristics at high temperatures of Au Schottky contact to n-type GaAs

    SciTech Connect (OSTI)

    Özerli, Halil; Karteri, ?brahim; Karata?, ?ükrü; Altindal, ?emsettin

    2014-05-01

    Highlights: • The electronic parameters of the diode under temperature were investigated. • The barrier heights have a Gaussian distribution. • Au/n-GaAs diode exhibits a rectification behavior. - Abstract: We have investigated the temperature-dependent current–voltage (I–V) and capacitance–voltage (C–V) characteristics of Au/n-GaAs Schottky barrier diodes (SBDs) in the temperature range of 280–415 K. The barrier height for the Au/n-type GaAs SBDs from the I–V and C–V characteristics have varied from 0.901 eV to 0.963 eV (I–V) and 1.234 eV to 0.967 eV (C–V), and the ideality factor (n) from 1.45 to 1.69 in the temperature range 280–415 K. The conventional Richardson plots are found to be linear in the temperature range measured. Both the ln(I{sub 0}/T{sup 2}) versus (kT){sup ?1} and ln(I{sub 0}/T{sup 2}) versus (nkT){sup ?1} plots gives a straight line corresponding to activation energies 0.773 eV and 0.870 eV, respectively. A ?{sub b0} versus 1/T plot was drawn to obtain evidence of a Gaussian distribution of the BHs, and values of ?{sup ¯}{sub b0} = 1.071 eV and ?{sub 0} = 0.094 V for the mean BH and zero-bias standard deviation have been obtained from this plot.

  5. Determination of bandgap states in p-type In[subscript 0.49]Ga[subscript 0.51]P grown on SiGe/Si and GaAs by deep level optical spectroscopy and deep level transient spectroscopy

    E-Print Network [OSTI]

    Gonzalez, Maria

    The presence and properties of traps in p-type In[subscript 0.49]Ga[subscript 0.51]P grown on low dislocation density, metamorphic Ge/SiGe/Si substrates and GaAs substrates were determined using deep level transient ...

  6. Utilization of by-product gypsum in construction 

    E-Print Network [OSTI]

    Stephenson, Angela Lorraine

    1987-01-01

    -3 meters), the slurry is fed to an alternative pond. The first pond is then left to dry up and for further maintenance work to reelevate the dikes with a dragline. Advantages for using this "gyp pile" or "gyp stack" method of waste disposal include (1...

  7. Separation of Mercury from Flue Gas Desulfurization Scrubber Produced Gypsum

    SciTech Connect (OSTI)

    Hensman, Carl, E., P.h.D; Baker, Trevor

    2008-06-16

    Frontier Geosciences (Frontier; FGS) proposed for DOE Grant No. DE-FG02-07ER84669 that mercury control could be achieved in a wet scrubber by the addition of an amendment to the wet-FGD scrubber. To demonstrate this, a bench-scale scrubber and synthetic flue-gas supply was designed to simulate the limestone fed, wet-desulfurization units utilized by coal-fired power plants. Frontier maintains that the mercury released from these utilities can be controlled and reduced by modifying the existing equipment at installations where wet flue-gas desulfurization (FGD) systems are employed. A key element of the proposal was FGS-PWN, a liquid-based mercury chelating agent, which can be employed as the amendment for removal of all mercury species which enter the wet-FGD scrubber. However, the equipment design presented in the proposal was inadequate to demonstrate these functions and no significant progress was made to substantiate these claims. As a result, funding for a Phase II continuation of this work will not be pursued. The key to implementing the technology as described in the proposal and report appears to be a high liquid-to-gas ratio (L/G) between the flue-gas and the scrubber liquor, a requirement not currently implemented in existing wet-FGD designs. It may be that this constraint can be reduced through parametric studies, but that was not apparent in this work. Unfortunately, the bench-scale system constructed for this project did not function as intended and the funds and time requested were exhausted before the separation studies could occur.

  8. Gypsum and Polyacrylamide Soil Amendments Used With High Sodium Wastewater 

    E-Print Network [OSTI]

    Gardiner, Duane

    1996-01-01

    Using wastewater for irrigation of crops represents an attractive alternative to disposal. Typically, municipal wastewaters are high in sodium, and the resulting high sodium absorption ratio (SAR) alters the soil structure making it more impermeable...

  9. ORIGINAL PAPER Production of glassceramics from heavy metal gypsum

    E-Print Network [OSTI]

    Volinsky, Alex A.

    (973 K, 2 h) and a crystallization stage (1,173 K, 1 h). The main crystalline phase of the obtained is a product of the stainless steel pickling waste liquor disposed by the lime neutralization precipita- tion properties and randomly oriented crystals with some resi- dual glass with

  10. Perception and Value of the Fresco in the Bronze Age Aegean

    E-Print Network [OSTI]

    Giffin, Sarah J

    2011-01-01

    the Painted Plaster. London: Equinox Publishing Ltd. Chapin,the Painted Plaster. London: Equinox Publishing Ltd. 10 This

  11. The detrimental effects of salinity on rooting of coleus cuttings and their alleviation with gypsum 

    E-Print Network [OSTI]

    Janssen, Antonius Hendrick

    1981-01-01

    concen- trations 2 Electrical conductivities (E. C. ) and osmolalities of 5 increasing salt solutions containing a 1/10- strength Hoagland's solution . 3 Electrical conductivities (E. C. ) of 4 NaCl solutions with increasing CaSO4 concentrations 4... of NaCl was due to a Na+ and/or Cl 1nhibition, a general 1on1c effect and/or osmot1c stresses of the salt solutions. 3. To determine if CaS04 reduces the adverse effects of increasing salinity in nutrient solutions and a peat-styra- foam propagation...

  12. Response of GaAs to fast intense laser pulses 

    E-Print Network [OSTI]

    Graves, JS; Allen, Roland E.

    1998-01-01

    , Parallel Algorithms in Com- puational Science ~Springer-Verlag, New York, 1991!. 30 R. E. Allen, Phys. Rev. B 50, 18 629 ~1994!. 31 J. Graves and R. Allen, in Tight-Binding Approach to Computa- tional Materials Science, edited by P.E.A. Turchi, A. Gonis...

  13. Electronic contribution to friction on GaAs

    E-Print Network [OSTI]

    Qi, Yabing; Applied Science and Technology Graduate Group, UC Berkeley; Dept. of Materials Sciences and Engineering, UC Berkeley

    2008-01-01

    approximately 1 nm thick oxide layer. Charge accumulation orcovered with a thin oxide layer, o?ering an interesting waycovered with a thin oxide layer as a function of bias

  14. Gypsum scale formation on a heated copper plate under natural convection conditions and produced water remediation technologies review

    E-Print Network [OSTI]

    Mirhi, Mohamad H. (Mohamad Hussein)

    2013-01-01

    Scaling or crystallization fouling of unwanted salts is one of the most challenging and expensive problems encountered in different applications such as heat exchangers and thermal water treatment technologies. Formation ...

  15. The use of gypsum and a coal desulfurization by-product to ameliorate subsoil acidity for alfalfa growth 

    E-Print Network [OSTI]

    Chessman, Dennis John

    2004-09-30

    Acid soils limit the growth of aluminum-(Al) sensitive crops such as alfalfa (Medicago sativa L.). Management of acid subsoils can be difficult due to physical and economic constraints. Field experiments were conducted ...

  16. Teaching Direct Marketing and Small Farm Viability: Resources for Instructors, 2nd Edition. Unit 6 - Building Resilience: Small Farm Planning and Operations

    E-Print Network [OSTI]

    2015-01-01

    Soil Tests Seed Amendments Compost Manure Gypsum Kelp MealSoil Tests Seed Amendments Compost Manure Gypsum Kelp Meal

  17. Evidence for field enhanced electron capture by EL2 centers in semi-insulating GaAs and the effect on GaAs radiation detectors

    E-Print Network [OSTI]

    Terry, Fred L.

    Yosef Eisen Soreq Nuclear Research Center, Israel Atomic Energy Commission, Yavne 70600, Israel Received information of the original energy absorbed.4 Ideally, Schottky barrier devices should demonstrate a changing energy level referenced from the conduction band, and Efn is the quasi-Fermi energy referenced from

  18. Edinburgh College of Art : cast collection and architecture 

    E-Print Network [OSTI]

    Stoica, Ruxandra-Iulia; Stewart, Margaret

    2012-01-01

    The Edinburgh Cast Collection comprises 265 plaster casts of Antique, Renaissance, and Gothic statues, bas reliefs, and architectural passages held at the Edinburgh College of Art and the University of Edinburgh. The plaster casts at the Edinburgh...

  19. Advanced trans-tibial socket fabrication using selective laser sintering

    E-Print Network [OSTI]

    controlled milling machine carves a pattern for the socket from plaster or foam. The socket is then made

  20. Interactions of pod-zone pH and Ca concentrations on reproductive growth of groundnut (Arachis hypogaea L.)

    E-Print Network [OSTI]

    Murata, Monica R; Zharare, Godfrey Elijah; Hammes, Piet S

    2009-01-01

    Davis, 1994). Thus, both lime and gypsum applications areapplication of both lime and gypsum, which necessitates afor groundnut production. Lime applications in groundnut

  1. Incorporation of aqueous reaction kinetics and biodegradation into TOUGHREACT: Application of a multi-region model to hydrobiogeoChemical transport of denitrification and sulfate reduction

    E-Print Network [OSTI]

    Xu, Tianfu

    2008-01-01

    Region: quartz calcite gypsum goethite Hydro- Region: Na + ,minerals gypsum and goethite were assumed to be initiallyChem-Region, Fe generated from goethite dissolution and HS

  2. Reliability of cascaded THz frequency chains with planar GaAs circuits

    E-Print Network [OSTI]

    Ward, John

    understanding of the risks associated with diode failures has to be achieved. Therefore, the reliability for determining the safe operating range of varactor diode frequency multipliers. The work described in this paper can be ap- propriately placed to mitigate risk. Failure mechanisms associated with ESD, high

  3. Effect of interface states on the performance of GaAs p -i far-infrared

    E-Print Network [OSTI]

    Perera, A. G. Unil

    , Georgia 30303 H. C. Liu and M. Buchanan Institute for Microstructural Sciences, National Research Council Received 13 August 1999; accepted 2 November 1999 Interface states have been shown to have an appreciable by the energy of the direct ionization of shallow dopants in semiconductors, e.g., Si up to 40 m, Ge up to 220 m

  4. Light and heavy ion effects on damage clustering in GaAs quantum wells

    E-Print Network [OSTI]

    Nordlund, Kai

    of Technology, P.O. Box 692, 33101 Tampere, Finland c Optoelectronics Research Centre, Tampere University-00014, University of Helsinki, Finland b Institute of Materials Chemistry, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland Available online 10 January 2007 Abstract Recent experiments

  5. Long-wavelength fast semiconductor saturable absorber mirrors using metamorphic growth on GaAs substrates

    E-Print Network [OSTI]

    Vos, Willem L.

    . Okhotnikov Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, 33101 Tampere

  6. Plasma nitridation of thin Si layers for GaAs dielectrics D. M. Diatezua,b)

    E-Print Network [OSTI]

    Rockett, Angus

    logarithmically with time. A model based on electron tunneling is proposed to explain the results. Capacitance suc- cessful FETs without electron confinement in the ICL and with low midgap trap densities at the Ga to an electron cyclotron resonance nitrogen plasma for varying times. The nitride thickness is shown to increase

  7. Experimental Evidence of Non-Diffusive Thermal Transport in Si and GaAs

    E-Print Network [OSTI]

    Johnson, Jeremy A.

    The length-scales at which thermal transport crosses from the diffusive to ballistic regime are of much interest particularly in the design and improvement of nano-structured materials. In this work, we demonstrate that ...

  8. Tightbinding moleculardynamics study of densityoptimized amorphous GaAs Hyangsuk Seong ? and Laurent J. Lewis y

    E-Print Network [OSTI]

    Lewis, Laurent J.

    Minces (GCM), Universit'e de Montr'eal, Case Postale 6128, Succursale Centre­Ville, Montr'eal, Qu disorder effects, and its relation to density, which we ob­ tain by minimization of the total energy

  9. GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies

    E-Print Network [OSTI]

    Li, Xiuling

    of these materials, and intimately integrating them on silicon or amorphous substrates (such as glass or plastic, in a manner that also allows the wafer to be reused for additional growths. We demon- strate some capabilities and logic gates on plates of glass, near-infrared imaging devices on wafers of silicon, and photovoltaic

  10. Gallium-rich reconstructions on GaAs(001) M. Pristovsek*; 1

    E-Print Network [OSTI]

    Schmidt, Wolf Gero

    - tion High-Energy Electron Diffraction. Annealing or dosing gallium above about 800 K invariably re- layer of gallium, it transforms into a (4 Â 6) reconstruction. The observed translational symmetries, and to contribute to their microscopic understanding. To this end we combine in-situ Reflection High-Energy Electron

  11. Mechanics Design for Stretchable, High Areal Coverage GaAs Solar Module

    E-Print Network [OSTI]

    Rogers, John A.

    . In this paper, an improved trench design is proposed and verified by finite ele- ment analysis (FEA), through science enable the integration of advanced semiconductor devices with ultralow modulus substrates to yield to stretch like a rubber band, twist like a rope, and bend over the tip of a pencil [1]. These capabilities

  12. Bismuth-induced phase control of GaAs nanowires grown by molecular...

    Office of Scientific and Technical Information (OSTI)

    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu-Tian Road, Shanghai 200083 (China) Materials Engineering,...

  13. Antimonide-Based Long-Wavelength Lasers on GaAs Substrates

    SciTech Connect (OSTI)

    KLEM,JOHN F.; Blum, O.

    2000-08-17

    We have investigated the use of GaAsSb in edge-emitting laser active regions, in order to obtain lasing near 1.3 {micro}m. Single quantum well GaAsSb devices display electroluminescence at wavelengths as long as 1.34 {micro}m, but substantial blueshifts occur under high injection conditions. GaAsSb single quantum well edge emitters have been obtained which lase at 1.275 {micro}m with a room-temperature threshold current density as low as 535 A/cm{sup 2}. Modification of the basic GaAsSb/GaAs structure with the addition of InGaAs layers results in a strongly type-II band alignment which can be used to further extend the emission wavelength of these devices. Using GaAsSb/InGaAs active regions, lasers emitting at 1.17 {micro}m have been obtained with room-temperature threshold current densities of 120 A/cm{sup 2}, and devices operating at 1.29 {micro}m have displayed thresholds as low as 375 A/cm{sup 2}. Characteristic temperatures for devices employing various GaAsSb-based active regions have been measured to be 60-73 K.

  14. Materials Science and Engineering B74 (2000) 5660 GaAs homojunction interfacial workfunction internal

    E-Print Network [OSTI]

    Perera, A. G. Unil

    2000-01-01

    30303, USA b Institute for Microstructural Sciences, National Research Council, Ottawa, Ont., Canada K1A-mm Telescope (FIRST) programs, for studying interacting galaxies, star forma- tion and composition of the detector after device processing and the energy-band diagram. Sec- ondary ion mass spectroscopy (SIMS

  15. Recent improvements in materials for thin GaAs and multibandgap solar cells

    SciTech Connect (OSTI)

    Benner, J.P.

    1985-05-01

    The High Efficiency Concepts Program at SERI supports research on III-V compound semiconductors with the objective of achieving the maximum attainable photovoltaic conversion efficiencies for terrestrial solar electric power. The outcome of this research may also affect the future of space photovoltaic cells. While the interest in thin-film, high-efficiency solar cells for terrestrial applications is driven principally by consideration of system costs, such cells would also improve the power density of space power arrays.

  16. Two-dimensional electron-gas actuation and transduction for GaAs nanoelectromechanical systems

    E-Print Network [OSTI]

    Roukes, Michael L.

    -frequency displacement transduction is achieved by measuring the ac emf developed across the 2DEG in the presence. In longitudinal resistance measurements, we detected a low field maximum, corre- sponding to maximal boundary

  17. ALD high-k and higher-k integration on GaAs Ozhan Koybasi 1)

    E-Print Network [OSTI]

    (N,N'-diisopropylformidinate), and lutetium tris(N,N'-diethylformamidinate) reacted with water vapor at 350 o C. The dielectric structures

  18. Non-Collinear Paramagnetism of a GaAs Two-Dimensional Hole System

    E-Print Network [OSTI]

    Yeoh, L. A.; Srinivasan, A.; Klochan, O.; Winkler, R.; Zülicke, U.; Simmons, M. Y.; Ritchie, D. A.; Pepper, M.; Hamilton, A. R.

    2014-12-03

    - plane field Bx aligned along [2¯33]. (b) Schematic of the evo- lution of the Landau levels, starting with perpendicular field Bz, and applying +Bx (red, +?) and in part (c) applying ?Bx (blue, ??). (d) Magnetoresistance ?xx for different tilt angles...

  19. Scanning capacitance microscopy of ErAs nanoparticles embedded in GaAs pn junctions

    E-Print Network [OSTI]

    Yu, Edward T.

    the subject of intense research for applications such as multijunction tan- dem solar cells,1 thermoelectric

  20. The design of GaAs HEMT and HBT Bessel-type transimpedance amplifiers 

    E-Print Network [OSTI]

    Adeyemi, Oluwafemi Ibukunoluwa

    2007-04-25

    ………….. 7 2.5 Factors Affecting BER and Sensitivity………….……... 9 2.5.1 Noise………………………………………. 9 2.5.2 Bandwidth…………………………………. 12 2.6 Eye Diagrams ………….………………………………. 15 2.6.1 Transfer Functions and Jitter Analysis. Using Eye...…………………………………... 8 Fig. 2.5. Illustration of the Gaussian Spread of the Output Voltage of a Noisy TIA……………………………………………………... 9 Fig. 2.6. Practical BER Curve Showing Deviation of Actual BER From (2.1)……………………………………………………………. 11 Fig. 2.7. Effect...

  1. Atomic structure of postgrowth annealed epitaxial Fe/(001)GaAs interfaces

    E-Print Network [OSTI]

    LeBeau, James; Hu, Qi O.; Palmstrom, Christopher; Stemmer, Susanne

    2008-01-01

    line pro?le across the interface along the line indicated inHAADF images of the GaAs/Fe interface along ?a? ?11 0? GaAsindicates the location of an interface step. Arrows in ?b?

  2. Double Power Output for GaAs Solar Cells Embedded in Luminescent Waveguides

    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: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformation Current HAB PacketDieselAbsorption Techniques | Stanford SynchrotronPower

  3. Bismuth-induced phase control of GaAs nanowires grown by molecular beam

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing Bacteria (Technical Report) | SciTechReport)(Technical Report)cellsEnergyepitaxy

  4. NONEQUILIBRIUM SULFUR CAPTURE & RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR

    SciTech Connect (OSTI)

    Bert Zauderer

    2003-04-21

    Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. The reacted particles impact and melt in the liquid slag layer on the combustor wall by the centrifugal force of the swirling combustion gases. Due to the low solubility of sulfur in slag, it must be rapidly drained from the combustor to limit sulfur gas re-evolution. Prior analyses and laboratory scale data indicated that for Coal Tech's 20 MMBtu/hour, air-cooled, slagging coal combustor slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to validate this sulfur-in-slag model in a group of combustor tests. A total of 36 days of testing on the combustor were completed during the period of performance of this project. This was more that double the 16 test days that were required in the original work statement. The extra tests were made possible by cost saving innovations that were made in the operation of the combustor test facility and in additional investment of Coal Tech resources in the test effort. The original project plan called for two groups of tests. The first group of tests involved the injection of calcium sulfate particles in the form of gypsum or plaster of Paris with the coal into the 20 MMBtu/hour-combustor. The second group of tests consisted of the entire two-step process, in which lime or limestone is co-injected with coal and reacts with the sulfur gas released during combustion to form calcium sulfate particles that impact and dissolve in the slag layer. Since this sulfur capture process has been validated in numerous prior tests in this combustor, the primary effort in the present project was on achieving the high slag flow rates needed to retain the sulfur in the slag.

  5. Use of coconut fiber as a low-cost thermal insulator

    SciTech Connect (OSTI)

    Kochhar, G.S.; Manohar, K. [Univ. of the West Indies, St. Augustine (Trinidad and Tobago)

    1997-11-01

    Cost is one of the major factors to be considered when choosing a thermal insulator. Design engineers continuously strive to provide the best at the lowest possible cost. In the tropics climate conditions are essentially hot and humid and a cause for daily discomfort. To some extent, air-conditioning of buildings has solved this problem. The major deterrent to air-conditioning is the exorbitant cost of imported thermal insulation materials. This has prompted a search for local, low-cost but effective thermal insulation for buildings. Coconut fiber is available at minimal cost from the copra industry in Trinidad, as it is a waste product from the coconut. The viability of using coconut fiber as building thermal insulation was explored by conducting thermal conductivity tests on 200 mm X 400 mm X 60 mm thick slab-like specimens. The test equipment used was a locally designed constant temperature hot box apparatus. This apparatus was designed to test slab-like specimens under steady-state conditions. The reliability if this experimental set up was checked using Gypsum Plaster. The thermal conductivity test results for coconut fiber over the density range 30 kg/m{sup 3} to 115 kg/m{sup 3} showed the characteristic hooked shape graph for fibrous material. For the 60 mm thick specimens at a mean temperature of 39 C, a minimum thermal conductivity of 0.058 W/mK occurred at an optimum density of 85 kg/m{sup 3}. The thermal conductivity of commonly used industrial insulators, namely loose-fill expanded vermiculite, cellular glass and blanket fiber glass, at a mean temperature of 38 C are 0.066 W/mK, 0.061 W/mK and 0.052 W/mK respectively. When compared, these results show that air dried coconut fiber has far reaching potential for use as an effective building thermal insulation.

  6. Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2O3; Sn;

    E-Print Network [OSTI]

    Garmestani, Hamid

    ferrocyanide (s) KMnO4 : potassium permanganate (s) FeCl3 : ferric chloride (s) NH4SO5 : ammonium persulfate (s

  7. Fabrication of wideband optoelectronic differential amplifier using a balanced receiver on a semi-insulating GaAs substrate 

    E-Print Network [OSTI]

    Choi, Kyoo Nam

    1989-01-01

    bandwidth. The monolithic receiver design described here has greatly reduced these undesirable effects and allowed multi-gigshertz performance. Balanced receivers have been fabricated with photoconductive gap widths of 5 pm and 3 Izrn... and supplies and to Jim Gardner for laser scribing and reticle fabrication support. I would especially like to thank Victor Swenson for his help in diagnosing and repairing the many equipment problems and instructions on equipment operation. I would also...

  8. Wide-field-of-view GaAs AlxOy one-dimensional photonic crystal filter

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    the environment (e.g., Sun, Moon, and other sources). The transmission bandwidth of such a filter needs to be wide exist, they require specialized materials. Other techniques, such as use of wide-angle light collectors

  9. Highly polarized emission in spin resolved photoelectron spectroscopy of alpha-Fe(001)/GaAs(001)

    E-Print Network [OSTI]

    Tobin, James

    2011-01-01

    of great interest to the spintronic and magneto-electronicpossibilities of spintronic or magneto-electronic devices [future applications of spintronic devices. One possibility

  10. Femtosecond-scale response of GaAs to ultrafast laser pulses RID A-7793-2008 

    E-Print Network [OSTI]

    Dumitrica, T.; Allen, Roland E.

    2002-01-01

    into the conduction band, the lattice is destabilized and the electronic band gap collapses to zero. This confirms the nonthermal nature of recently observed structural changes driven by electronic excitations and occurring during the first few hundred femtoseconds....

  11. Second-Harmonic Generation in GaAs Photonic Crystal Cavities in (111)B and (001) Crystal Orientations

    E-Print Network [OSTI]

    Vuckovic, Jelena

    media such as quantum dots or quantum wells,10-12 as well as potential on-chip integration to overcome this limitation and take advantage of III-V materials, including growth of multiple quantum wells-harmonic generation and sum frequency generation in photonic crystal cavities in materials such as InP,16 GaP,17 Ga

  12. Highly Ordered Ga Nanodroplets on a GaAs Surface Formed by a Focused Ion Beam Qiangmin Wei,1

    E-Print Network [OSTI]

    Lu, Wei

    quantum dots by low-energy ion sputtering on a surface has been reported in several semiconductor sys quantum dots on the surface. The mechanism involves the balance between roughening and smoothing actions], Ge [10], as well as a variety of III­V compounds (GaSb [11], InP [12], and InSb [13]) can form

  13. Calculations of bound and resonant electronic states for the GaAs (111) (2x2) reconstructed surface 

    E-Print Network [OSTI]

    Blount, Samuel Stephen

    1985-01-01

    planar wavevector, pt, (k, E). Procedure Performing the electronic surface state calculation basically involves a four step procedure. These are: 1) Calculate the tight, -binding bulk Hamiltonian, Ho(k), 2) Find the subspace bulk Green's function in t... transform bulk coordinates to surface adapted co- ordinates are: j& = ? 45' (3dfio) 8 = cos '( ? ) = 54. 7 3 (3. iffy) tt =0' (3. i6c) where these angles are defined explicitly in Goldstein. Once Ho(k) is rotated to surface adapted coordinates...

  14. Santa Cruz and the Cowell Ranch, 1890-9641

    E-Print Network [OSTI]

    Regional History Project, UCSC Library; Cardiff, George; Calciano, Elizabeth Spedding

    1965-01-01

    tile Cardiff: Yes, cement, lime, plaster, brick -- allbasement, the foundation, is lime rock, three or four feetHe bought some additional lime quarries, lime kilns. The

  15. Agreement Type Union

    National Nuclear Security Administration (NNSA)

    Plasterers and Cement Mason International Association 1 International Brotherhood of Electrical Workers 396 6 International Brotherhood of Electrical Workers 357 50 International...

  16. DATES TO REMEMBER July 7 Perennial Peanut Field Day -Moultrie, GA

    E-Print Network [OSTI]

    Watson, Craig A.

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 TOBACCO Checking Tobacco Barns for Heat Exchanger Leaks or are of the virginia market-type, apply gypsum by the time plants are blooming. Gypsum is a readily available source

  17. Janet and Grant Brians: Brians Ranch

    E-Print Network [OSTI]

    Farmer, Ellen

    2010-01-01

    Brians: Well, putting on compost and gypsum have been two ofback in the soil, and compost and things. But we didn’tthen putting gypsum and compost in, gradually it’s getting

  18. PHYSICAL REVIEW B 88, 205203 (2013) Magnetic anisotropy of single Mn acceptors in GaAs in an external magnetic field

    E-Print Network [OSTI]

    Flatte, Michael E.

    2013-01-01

    , London, WC1E 7JE, United Kingdom 5 Department of Physics, University of New Hampshire, Durham, New London (UCL), London, WC1H 0AH, United Kingdom 4 Department of Electronic and Electrical Engineering, UCL Hampshire 03824-3520, USA 6 Department of Physics and Astronomy, UCL, London, WC1E 6BT, United Kingdom 7

  19. Characterization of photochemically unpinned GaAs c. W. Wilmsen,a) P. D. Kirchner, J. M. Baker, D. T. McInturff, G. D. Pettit,

    E-Print Network [OSTI]

    Woodall, Jerry M.

    water was not applied to the substrate. The degree ofunpinning produced by this process has been found in deionized (DI) water. Some samples then received a final chemical treatment as The roomAs ( 100) surface has recently been reported by both photowashing and by Na2S'9H20 treatments. Both

  20. Damage production in GaAs and GaAsN induced by light and heavy ions C. Bjrkas,a

    E-Print Network [OSTI]

    Nordlund, Kai

    , Finland V. D. S. Dhaka Institute of Materials Chemistry, Tampere University of Technology, P.O. Box 692, 33101 Tampere, Finland M. Pessa Optoelectronics Research Centre, Tampere University of Technology, P

  1. Conductivity and structure of ErAs nanoparticles embedded in GaAs pn junctions analyzed via conductive atomic force microscopy

    E-Print Network [OSTI]

    Yu, Edward T.

    in III-V semiconductors J. Appl. Phys. 111, 103706 (2012) Role of surface trap states on two-dimensional electron gas density in InAlN/AlN/GaN heterostructures Appl. Phys. Lett. 100, 152116 (2012) Free carrier studies of macroscopic tunnel junctions. VC 2012 American Institute of Physics. [http://dx.doi.org/10

  2. Oxygen vacancy induced magnetization switching in Fe{sub 3}O{sub 4} epitaxial ultrathin films on GaAs(100)

    SciTech Connect (OSTI)

    Huang, Zhaocong; Chen, Qian; Zhai, Ya E-mail: jlwang@seu.edu.cn; Wang, Jinlan E-mail: jlwang@seu.edu.cn; Xu, Yongbing; Wang, Baoping

    2015-05-04

    The magnetic and transport properties of half metallic Fe{sub 3}O{sub 4}, which are sensitive to the stoichiometry, are the key issue for applications in spintronics. An anomalous enlargement of the saturation magnetic moment is found in a relatively thick sample of epitaxial Fe{sub 3}O{sub 4} film by post-growth oxidation method. The investigation of the thickness dependence of magnetic moment suggests that the enhanced magnetism moment may come from the existence of oxygen vacancies. First-principles calculations reveal that with oxygen vacancies in Fe{sub 3}O{sub 4} crystal the spin of Fe ions in the tetrahedron site near the vacancy is much easier to switch parallel to the Fe ions in the octahedron site by temperature disturbance, supported by the temperature dependence of magnetic moment of Fe{sub 3}O{sub 4} films in experiment.

  3. Effects of strain and quantum confinement in optically pumped nuclear magnetic resonance in GaAs: Interpretation guided by spin-dependent band structure calculations

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

    Wood, R. M.; Saha, D.; McCarthy, L. A.; Tokarski, III, J. T.; Sanders, G. D.; Kuhns, P. L.; McGill, S. A.; Reyes, A. P.; Reno, J. L.; Stanton, C. J.; et al

    2014-10-29

    A combined experimental-theoretical study of optically pumped NMR (OPNMR) has been performed in a GaAs/Al0.1Ga0.9As quantum well film with thermally induced biaxial strain. The photon energy dependence of the Ga-71 OPNMR signal was recorded at magnetic fields of 4.9 and 9.4 T at a temperature of 4.8-5.4 K. The data were compared to the nuclear spin polarization calculated from differential absorption to spin-up and spin-down states of the conduction band using a modified Pidgeon Brown model. Reasonable agreement between theory and experiment is obtained, facilitating assignment of features in the OPNMR energy dependence to specific interband transitions. Despite the approximationsmore »made in the quantum-mechanical model and the inexact correspondence between the experimental and calculated observables, the results provide insight into how effects of strain and quantum confinement are manifested in OPNMR signals« less

  4. GaAs 0.5 dB NF dual-loop negative-feedback broadband low-noise amplifier IC

    E-Print Network [OSTI]

    Serdijn, Wouter A.

    ) designed for the square kilometre array is presented. Effects of transformer non-idealities on LNA is obtained by increasing the collecting area to approxi- mately one square kilometre. This square kilometre array (SKA) [1] employs approximately 100 million antennas that are connected in a phased array, forming

  5. Growth, microstructure, and luminescent properties of direct-bandgap InAlP on relaxed InGaAs on GaAs substrates

    E-Print Network [OSTI]

    with applications in solid-state lighting, display devices, and multi-junction solar cells. We report on the growth

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

    SciTech Connect (OSTI)

    Wheeldon, Jeffrey F.; Valdivia, Christopher E.; Walker, Alex; Kolhatkar, Gitanja; Hall, Trevor J.; Hinzer, Karin; Masson, Denis; Riel, Bruno; Fafard, Simon; Jaouad, Abdelatif; Turala, Artur; Ares, Richard; Aimez, Vincent

    2010-10-14

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

  7. Catalyst Mediated Growth and Optical Properties of Group III-V Nanowires: Au catalyzed GaAs and Self-catalyzed InP

    E-Print Network [OSTI]

    Park, Jeung Hun

    2013-01-01

    characterization of InP quantum dots [16], nanowire [17],effects. Recently InP quantum dots [13], nanowire [14], and

  8. Growth, microstructure, and luminescent properties of direct-bandgap InAlP on relaxed InGaAs on GaAs substrates

    E-Print Network [OSTI]

    Beaton, Daniel A.

    Direct-bandgap InAlP alloy has the potential to be an active material in nitride-free yellow-green and amber optoelectronics with applications in solid-state lighting, display devices, and multi-junction solar cells. We ...

  9. PHYSICAL REVIEW B 84, 245306 (2011) Formation process and superparamagnetic properties of (Mn,Ga)As nanocrystals in GaAs

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    2011-01-01

    of Physics, Polish Academy of Sciences, al. Lotnik´ow 32/46, PL-02-668 Warszawa, Poland 3 Department a transition metal (TM) compound (to form a condensed magnetic semiconductor) or a TM.2,3 Interest- ingly

  10. Graphite based Schottky diodes formed on Si, GaAs, and 4H-SiC S. Tongay, T. Schumann, and A. F. Hebarda

    E-Print Network [OSTI]

    Hebard, Arthur F.

    of the graphite electrode is a single graphene sheet, we expect that graphene/semiconductor barriers will manifest at the semiconductor sur- face for two reasons: the graphene sheets of the graphite are robustly impervious the formation of semimetal graphite/semiconductor Schottky barriers where the semiconductor is either silicon Si

  11. Pseudomorphic growth and strain relaxation of a-Zn3P2 on GaAs(001) by molecular beam epitaxy

    E-Print Network [OSTI]

    Kimball, Gregory

    -abundant semiconductor material that has excellent optoe- lectronic properties. Zn3P2 is an interesting, potentially for scalable thin-film applications. Studies of Zn3P2 as a PV material have primarily focused on the properties]. These properties, in addition to the abundance and low cost of elemental zinc and phosphorus, make Zn3P2 attractive

  12. Heteroepitaxy of single-crystal LaLuO3 on GaAs,,111...A by atomic layer Yiqun Liu,1

    E-Print Network [OSTI]

    lutetium oxide LaLuO3 has been widely studied as an alternative gate dielectric to replace silicon di from the precursors including lanthanum tris N,N -diisopropylformamidinate , lutetium tris N

  13. Hot-electron mean free path of ErAs thin films grown on GaAs determined by metal-base transistor ballistic electron emission spectroscopy

    E-Print Network [OSTI]

    Russell, Kasey

    of thermal energy convert- ing devices11,12 and multijunction solar cells.13 Yet despite the promising

  14. Evidence for selective delocalization of N-pair states in dilute GaAs1xNx B. A. Weinstein,1

    E-Print Network [OSTI]

    Weinstein, Benard.A.

    and quarternary alloys on near-infrared light-emitting devices,7 multijunction solar cells,8 and het- erojunction

  15. Effects of strain and quantum confinement in optically pumped nuclear magnetic resonance in GaAs: Interpretation guided by spin-dependent band structure calculations

    SciTech Connect (OSTI)

    Wood, R. M.; Saha, D.; McCarthy, L. A.; Tokarski, III, J. T.; Sanders, G. D.; Kuhns, P. L.; McGill, S. A.; Reyes, A. P.; Reno, J. L.; Stanton, C. J.; Bowers, C. R.

    2014-10-29

    A combined experimental-theoretical study of optically pumped NMR (OPNMR) has been performed in a GaAs/Al0.1Ga0.9As quantum well film with thermally induced biaxial strain. The photon energy dependence of the Ga-71 OPNMR signal was recorded at magnetic fields of 4.9 and 9.4 T at a temperature of 4.8-5.4 K. The data were compared to the nuclear spin polarization calculated from differential absorption to spin-up and spin-down states of the conduction band using a modified Pidgeon Brown model. Reasonable agreement between theory and experiment is obtained, facilitating assignment of features in the OPNMR energy dependence to specific interband transitions. Despite the approximations made in the quantum-mechanical model and the inexact correspondence between the experimental and calculated observables, the results provide insight into how effects of strain and quantum confinement are manifested in OPNMR signals

  16. Electrically active Er doping in InAs, In[sub 0.53]Ga[sub 0.47]As, and GaAs

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing(Journal Article) | SciTech(Journal Article) |Continuum (Technical Report)(Journal

  17. Electrically active Er doping in InAs, In{sub 0.53}Ga{sub 0.47}As, and GaAs

    Office of Scientific and Technical Information (OSTI)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfate Reducing(Journal Article) | SciTech(Journal Article) |Continuum (Technical

  18. Building Stones

    E-Print Network [OSTI]

    2012-01-01

    UEE 2012 “Concrete” or “lime plaster” made from limestoneto reduce (calcine) calcite (CaCO 3 ) to “quick lime” (CaO).When powdered quick lime is mixed with water (a process

  19. THE CIRCULATORY SYSTEM AND BLOOD General charectertllUCIL______ _ _______ 23ll

    E-Print Network [OSTI]

    ·system is compensated by thepulsa..ting vesaelsof the mantle and by the contractions of two aeeessery hea.rt8on from which the heart has been re- moved; after the material has l!8t, the plaster molds

  20. Moving Towards a Holistic View of

    E-Print Network [OSTI]

    Gray, Matthew

    /32" (15mm) plywood decking Above grade exterior walls 2" x 6" wood studs @ 16" (400mm) o/c, #15 organic" wood studs @ 24" (600mm) o/c, R13 fiberglass batt insulation, poly vapor barrier, 12mm gypsum board 1, 12mm gypsum board Partition walls 2"x4" wood studs @ 16" (400mm) o/c, 12mm gypsum board two sides 1

  1. Process Heating: A Special Supplement to Energy Matters

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

    Value-Added Product Areas * Steel * Automotive Parts * Gypsum * Glass * Appliances * Foundry * Basic Chemicals * Speciality Steels * Paint * Ores and Minerals * Food * Computer...

  2. Teaching Organic Farming and Gardening: Resources for Instructors, 3rd Edition. Part 2 - Applied Soil Science

    E-Print Network [OSTI]

    2015-01-01

    minerals, such as iron, lime (calcium carbonate), and4. Acid soils and liming Lime (calcium carbonate) is addedhigh in calcium (such as lime, gypsum, or dolomite) or by

  3. Building America Technlogy Solutions for New and Existing Homes...

    Energy Savers [EERE]

    mitigate moisture issues: dimple mat; spray polyurethane foam insulation; moisture and thermal management systems for the floor; and paperless gypsum board and steel framing....

  4. PowerPoint Presentation

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

    pennies Gypsum, salt, anthracite coal, and gold ore Worksheets Handouts Directions: Label each plate with a number, 1 through 4. Place each rock sample on the plate that...

  5. Mercury Absorption in Aqueous Oxidants Catalyzed by Mercury(II) Lynn L. Zhao and Gary T. Rochelle*

    E-Print Network [OSTI]

    Rochelle, Gary T.

    and precipitated gypsum. In a recent pilot test of treating 500 m3/h of flue gas stream at a sludge incinerator

  6. Gallium Arsenide-Based Readout Electronics Thomas J. Cunningham and Eric R. Fossum

    E-Print Network [OSTI]

    Fossum, Eric R.

    to carrier freeze-out, so we expect GaAs readouts to produce less noise than silicon readouts at very low that operate at cryogenic temperatures. Presently, GaAs readout technology can draw from several types

  7. Sandia Energy - EC Publications

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

    Surfaces using Traceable Soil Components (137) BACK-CONTACTED AND SMALL FORM FACTOR GaAs SOLAR CELL (51) BACK-CONTACTED AND SMALL FORM FACTOR GaAs SOLAR CELL (197) BACK-CONTACTED...

  8. High efficiency, radiation-hard solar cells

    E-Print Network [OSTI]

    Ager III, J.W.; Walukiewicz, W.

    2004-01-01

    efficiency multijunction (MJ) solar cells use componentsin current multijunction (MJ) solar cells (GaAs and GaInP)

  9. Monolithically Peltier-cooled vertical-cavity surface-emitting lasers Paul FL Berger, Niloy K. Dutta, Kent D. Choquette, Ghulam Hasnain, and Naresh Chand

    E-Print Network [OSTI]

    Monolithically Peltier-cooled vertical-cavity surface-emitting lasers Paul FL Berger, Niloy K. The thermoelectric element is the n + -GaAs substrate based on the Peltier effect. A variation of active region contact on the n + -GaAs substrate. The thermoelectric (Peltier) ef- fect of the n f -GaAs substrate can

  10. CURRENT NEWS Sandwich Solar Cells May See Off Silicon

    E-Print Network [OSTI]

    Rogers, John A.

    to manufacture thin films of GaAs that also allowed versatility in the types of devices they could multiple layers of the material on a single wafer, creating a layered, "pancake" stack of GaAs thin films the photovoltaic (PV) cells are based on silicon. However, alternatives such as GaAs and other compound

  11. Vol. 3 No. 8 August 2013 www.advenergymat.deaatttttttt.......dddddddddddddddddddddeeeeeeeeeeeeeee

    E-Print Network [OSTI]

    Rogers, John A.

    the Power Output of Bifacial Thin-Film GaAs Solar Cells by Embedding Them in Luminescent Waveguides Dr. X Recent developments in epitaxial liftoff techniques for forming thin, high efficiency GaAs solar cells,6] Thin-film GaAs microscale cells (-cells) that combine epi- taxial liftoff from single or multilayer

  12. Metallic nanostructures for optoelectronic and photovoltaic applications

    E-Print Network [OSTI]

    Lim, Swee Hoe

    2009-01-01

    structures to thin film GaAs solar cells. The scattering ofthin film Si, GaAs and InGaAs multiple quantum well solar cells.We consider a GaAs based thin film solar cell. Texturing on

  13. Optical Design Considerations for High Conversion Efficiency in Photovoltaics

    E-Print Network [OSTI]

    Ganapati, Vidya

    2015-01-01

    Schermer, “26.1% thin-film GaAs solar cell using epitaxialFILTER Thin-­?Film  GaAs  Solar  Cell:  Re?ec-vity  Above  off solar cells [9], [10], where the thin GaAs film is

  14. The utilization of flue gas desulfurization waste by-products in construction brick 

    E-Print Network [OSTI]

    Berryman, Charles Wayne

    1992-01-01

    Millions of tons of waste by-products from Texas coal burning plants are produced each year. Two common byproducts are the fuel ashes and calcium sulfate (gypsum). Fuel ashes result from the burning of coal. Gypsum is a byproduct of the air...

  15. GaAs multiple-quantum-well reflector modulators with 4:l contrast ratios A. Salvador, K. Adorni,@K. Kishino,b) M. S. l%U, and H. Morkoq.

    E-Print Network [OSTI]

    ,,, G%,,As (3 X 1018cmv3 be- `) On leave from Shin-Etsu Handotai Co., Ltd., Gunma, Japan. "On leave from

  16. Luminescence properties of light-emitting diodes based on GaAs with the up-conversion Y{sub 2}O{sub 2}S:Er,Yb luminophor

    SciTech Connect (OSTI)

    Gruzintsev, A. N. [Russian Academy of Sciences, Institute of Problems of Microelectronics Technology (Russian Federation)], E-mail: gran@ipmt-hpm.ac.ru; Barthou, C.; Benalloul, P. [Institute des NanoSciences (France)

    2008-03-15

    Y{sub 2}O{sub 2}S luminophors doped with Er{sup 3+} and Yb{sup 3+} ions are produced by means of solid-phase synthesis and deposited onto standard AL123A infrared light-emitting diodes. When excited with 940 nm radiation from a light-emitting diode, the structures exhibit intense visible up-conversion luminescence. A maximal brightness of 2340 cd/m{sup 2} of green and red up-conversion luminescence at corresponding wavelengths around 550 and 600 nm is observed for the Y{sub 2}O{sub 2}S compound doped with 2 at % Er{sup 3+} ions and 6 at % Yb{sup 3+} ions. The ratio of the intensity of green (or red) up-conversion luminescence to the intensity of infrared Stokes luminescence increases with increasing applied voltage. The efficiency of visible emission of the light-emitting diode structures is {eta} = 1.2 lm/W at an applied voltage of 1.5 V.

  17. Dual passivation of GaAs (110) surfaces using O2/H2O and trimethylaluminum Tyler J. Kent, Mary Edmonds, Evgueni Chagarov, Ravi Droopad, and Andrew C. Kummel

    E-Print Network [OSTI]

    Kummel, Andrew C.

    , functionalization, and atomic layer deposition nucleation on the Ge(100) surface J. Chem. Phys. 140, 204708 (2014); 10.1063/1.4878496 Arsenic decapping and pre-atomic layer deposition trimethylaluminum passivation semiconductor surface during atomic layer deposition J. Chem. Phys. 133, 154704 (2010); 10

  18. VOLUME 80, NUMBER 21 P H Y S I C A L R E V I E W L E T T E R S 25 MAY 1998 Femtosecond Four-Wave Mixing Experiments on GaAs Quantum Wells

    E-Print Network [OSTI]

    Hohng, Sung Chul

    Materialwissenschaften, Phillips-Universtät Marburg, 35032 Marburg, Germany D. H. Woo, E. K. Kim, and S. H. Kim Korea when v2 is completely below the exciton energies, with no spectral overlap with the absorption profile further extended the usage of FWM into wide band gap materials such as ZnSe [4] and GaN [5]. Most

  19. 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 3115 www.advmat.de

    E-Print Network [OSTI]

    Javey, Ali

    ] In 1978, the first GaAs solar cell on glass was demonstrated by the use of ELT.[28] Yablono- vitch et al. used a similar process in the late 1980s for the fab- rication of thin film GaAs diode lasers and other of ELT dates back to 1975 when GaAs layers with micro-scale thicknesses were successfully transferred

  20. Detailed Balance Analysis and Enhancement of Open-Circuit Voltage in Single-Nanowire Solar Cells

    E-Print Network [OSTI]

    Fan, Shanhui

    of a thin film GaAs cell,20 a thin film GaAs cell with gratings,16 and a cell with a photonic crystal top- voltaics.1-3 Compared with traditional thin-film solar cells,4,5 the advantage of the nanowire cells out such a detailed balance analysis of a single nanowire solar cell, using gallium arsenide (GaAs

  1. Transcending QCD in Nanostructured Solar Cells G. Galli S. Kauzlarich

    E-Print Network [OSTI]

    achieved! - But: fracking of natural gas moved grid parity to 0.3$/W 2. Science/Technology: - GaAs: 29% lab

  2. Investigation of Spin-Based Phenomena in Candidate Spintronic Materials by Molecular Beam Epitaxy

    E-Print Network [OSTI]

    Swartz, Adrian

    2013-01-01

    Phenomena in Candidate Spintronic Materials by MolecularPhenomena in Candidate Spintronic Materials by Molecularmolecules) and candidate spintronic mate- rials (i.e. GaAs,

  3. THSE DE DOCTORAT Spcialit Physique

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    -thin GaAs and CIGS solar cells soutenue le 18 Décembre 2013 Composition du jury : M. PELOUARD Jean-Luc LPN

  4. Raman scattering in InAs/AlGaAs quantum dot nanostructures E. Giulotto,1,a

    E-Print Network [OSTI]

    As upper CL UCL with the same composition of LCL, and a 10 nm thick GaAs cap layer. Buffers and LCLs were

  5. Profiling the Built-In Electrical Potential in III-V Multijunction Solar Cells (Poster)

    SciTech Connect (OSTI)

    Jiang, C.-S.; Friedman, D. J.; Moutinho, H. R.; Al-Jassim, M. M.

    2006-05-01

    We have observed three electrical potentials at the top, tunneling, and bottom junctions of GnInP{sub 2}/GaAs tandem-junction solar cells, by performing the UHV-SKPM measurement. The effect of laser illumination was avoided by using GaAs laser with photon energy of 1.4 eV for the AFM operation. We also observed higher potentials at the atomic steps than on the terraces for both p-type GaInP{sub 2} epitaxial layer and p-type GaAs substrate, and found that the potential at steps of GaAs substrate depends on the step directions.

  6. MATERIALS AND MOLECULAR RESEARCH DIVISION, ANNUAL REPORT 1976

    E-Print Network [OSTI]

    Authors, Various

    2010-01-01

    thin film on low-cost sub- strates will be studied with the objective of improving the efficiency of polycrystalline GaAs solar cells.

  7. Investigation of Spin-Based Phenomena in Candidate Spintronic Materials by Molecular Beam Epitaxy

    E-Print Network [OSTI]

    Swartz, Adrian

    2013-01-01

    injection into semiconductors and graphene [343, 344, 345,effect for graphene compared to semiconductor or metallicfaces, the semiconductor GaAs, and graphene. Graphene, a

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

    E-Print Network [OSTI]

    Seal, Mark K.

    2015-01-01

    fabrication cost of multijunction solar cells, GaAs and InPfabrication of multijunction solar cells. At the interfacestructures in multijunction solar cells. Future work on this

  9. Process development for the fabrication of monolithic optoelectronic resonators on gallium arsenide substrates 

    E-Print Network [OSTI]

    Fairchild, Brock Wilson

    1990-01-01

    performance. The resonating structures were constructed on semi-insulating GaAs, doped GaAs, epitaxially-grown doped GaAs on GaAs and heterostructure Al- GaAs/GaAs/AlGaAs/GaAs substrates. A thin layer of Au-Ge and Ni was deposited on the substrates as a... loss microwave structure, were electroplated on the uncovered regions of the Au-Ge and Ni. After photoresist removal, the Au-Ge and Ni layers were removed from the unwanted regions. A backside metal was deposited and the sample was annealed. The four...

  10. Particle Size Distribution of Gypseous Samples 

    E-Print Network [OSTI]

    Arnett, Morgan P.

    2010-01-16

    Particle size distribution (PSD) of gypseous soils is important in the soil science community. When gypsum constitutes a major portion of the soil, its removal prior to PSD analysis distorts the results and may lead to ...

  11. RESPONSE OF UNCRACKED DRYWALL JOINTS AND PANELS TO BLAST VIBRATION

    E-Print Network [OSTI]

    the response of cracked and uncracked areas of gypsum board in two structures ­ one near a surface coal mine adjacent to construction or mining blasting. While a large database of case studies documenting

  12. Teaching Organic Farming and Gardening: Resources for Instructors, 3rd Edition. Part 1 - Skills and Practices

    E-Print Network [OSTI]

    2015-01-01

    of amendments such as compost and lime d) Allows soil to dryFertilizers such as gypsum/lime can improve soil structure;magnesium carbonate – dolomitic lime: added to acidic soils

  13. High Recovery Desalination of Brackish Water by Chemically-Enhanced Seeded Precipitation

    E-Print Network [OSTI]

    McCool, Brian Carey

    2012-01-01

    organic contaminants by lime softening. Water Research,of alkaline material (e.g. , lime) and gypsum powder intothe alkaline material (e.g. , lime) to form a slurry. 4. The

  14. Rise and fall of the Paratethys Sea during the Messinian Salinity Crisis W. Krijgsman a,

    E-Print Network [OSTI]

    Utrecht, Universiteit

    with elusive tectonic processes in the Gibraltar arc. A subsequent fall of Paratethyan water level closely isolated from the Atlantic Ocean, triggering widespread precipitation of gypsum (5.96­5.6 Ma), massive salt

  15. GARGZDAI "KRANTAS" SECONDARY SCHOOL

    E-Print Network [OSTI]

    Borissova, Daniela

    (limestone, dolomite, whiting, marble, gypsum, anhydrite, rock-salt) and water circulates. The areas beneficent. Tectonic movements. #12;FORMING CONDITIONS In Lithuania the intensive sinkhole zone takes the position

  16. Incorporating on-line process data into a diagnostic knowledge-based system 

    E-Print Network [OSTI]

    Lin, Kai Hsuan

    1994-01-01

    The objective of this research was to develop and implement an on-line gypsum wallboard manufacturing expert system incorporating on-line process monitoring information and statistical process control. In support of this objective, several sub...

  17. SOME ANALYTIC MODELS OF PASSIVE SOLAR BUILDING PERFORMANCE: A THEORETICAL APPROACH TO THE DESIGN OF ENERGY-CONSERVING BUILDINGS

    E-Print Network [OSTI]

    Goldstein, David Baird

    2011-01-01

    We evaluate lumped parameters for wood (studs) and thenfor (non-wood-stud-backed) gypsum board, and then combinethem. Consider first the wood studs. 0.15 x 1920 ft2 I The

  18. Partition wall subsystem modeling and effect on the coupled building system response

    E-Print Network [OSTI]

    Wood, Richard Lee

    2012-01-01

    light-weight (metal or wood stud) interior partition wall.both light-gauge steel and wood studs. Particular focus isusing 1/2 inch gypsum, on wood studs. The loading protocol

  19. Environmental chamber measurements of mercury flux from coal utilization by-products

    SciTech Connect (OSTI)

    Pekney, Natalie J.; Martello, Donald; Schroeder, Karl; Granite, Evan

    2009-05-01

    An environmental chamber was constructed to measure the mercury flux from coal utilization by-product (CUB) samples. Samples of fly ash, FGD gypsum, and wallboard made from FGD gypsum were tested under both dark and illuminated conditions with or without the addition of water to the sample. Mercury releases varied widely, with 7- day experiment averages ranging from -6.8 to 73 ng/m(2) h for the fly ash samples and -5.2 to 335 ng/m(2) h for the FGD/wallboard samples. Initial mercury content, fly ash type, and light exposure had no observable consistent effects on the mercury flux. For the fly ash samples, the effect of a mercury control technology was to decrease the emission. For three of the four pairs of FGD gypsum and wallboard samples, the wallboard sample released less (or absorbed more) mercury than the gypsum.

  20. User's Guide to the NIST Virtual Cement and Concrete Testing

    E-Print Network [OSTI]

    Bentz, Dale P.

    , a user may create starting microstructures of cement (gypsum, fly ash, etc.) particles in water, hydrate . 20 2.12 Menu Selection 11) Distribute fly ash phases amongst fly ash particles

  1. Environmental chamber measurements of mercury flux from coal utilization by-products

    SciTech Connect (OSTI)

    Pekney, N.J.; Martello, D.V.; Schroeder, K.T.; Granite, E.J.

    2009-05-01

    An environmental chamber was constructed to measure the mercury flux from coal utilization by-product (CUB) samples. Samples of fly ash, FGD gypsum, and wallboard made from FGD gypsum were tested under both dark and illuminated conditions with or without the addition of water to the sample. Mercury releases varied widely, with 7-day experiment averages ranging from -6.8 to 73 ng/m2 h for the fly ash samples and -5.2 to 335 ng/m2 h for the FGD/wallboard samples. Initial mercury content, fly ash type, and light exposure had no observable consistent effects on the mercury flux. For the fly ash samples, the effect of a mercury control technology was to decrease the emission. For three of the four pairs of FGD gypsum and wallboard samples, the wallboard sample released less (or absorbed more) mercury than the gypsum.

  2. Technology Solutions Case Study: Interior Foundation Insulation Upgrade-Minneapolis Residence

    SciTech Connect (OSTI)

    2013-10-01

    This interior foundation project employed several techniques to improve performance and mitigate moisture issues: dimple mat; spray polyurethane foam insulation; moisture and thermal management systems for the floor; and paperless gypsum board and steel framing.

  3. UBC Social Ecological Economic Development Studies (SEEDS) Student Report Life Cycle Assessment of the George F. Curtis Addition Building

    E-Print Network [OSTI]

    III Glass Felt 13442.883 m2 5/8" Regular Gypsum Board 8937.0811 m2 #15 Organic Felt 6721.4413 m2-Rated Type X Gypsum Board 42.4443 m2 Water Based Latex Paint 35.7273 L Glazing Panel 33.0513 Tonnes Aluminum Lumber, kiln-dried 4.1861 m3 Galvanized Sheet 4.0585 Tonnes Nails 1.9998 Tonnes Solvent Based Alkyd Paint

  4. Tremont House and Hotel Galvez Sustainablility Modifications 

    E-Print Network [OSTI]

    Arneson, C.

    2012-01-01

    of all recyclable materials throughout project ? Installation of fiberglass faced gypsum sheathing ? Hotel Galvez: ? Installation of windstorm windows in wood framed sashes ? Relocation of electric systems from the lower level to an exterior electric....e. glazing and window frames, metals, ceiling tiles ? For both projects: ? Installation of fiberglass faced gypsum sheathing ? Texturi wall finish ? Energy management system installation ? Conclusion & questions United Stated Custom House Hutchings...

  5. Community Geothermal Technology Program: Silica bronze project. Final report

    SciTech Connect (OSTI)

    Bianchini, H.

    1989-10-01

    Objective was to incorporate waste silica from the HGP-A geothermal well in Pohoiki with other refractory materials for investment casting of bronze sculpture. The best composition for casting is about 50% silica, 25% red cinders, and 25% brick dust; remaining ingredient is a binder, such as plaster and water.

  6. Remembrance of an absence Report by Cati Vaucelle

    E-Print Network [OSTI]

    Ishii, Hiroshi

    travail. I chose to dismember a Barbie doll that I created out of wax. The Barbie being for a while a representation of the woman for a child. I chose the white wax, the wax being a way a woman suffers regularly & the plaster sculpted with chisel, and the angelic face of the doll made of white wax. This sculpture is a tool

  7. The Feeding Mechanics of the Gizzard Shad (Dorosoma Cepedianum)

    E-Print Network [OSTI]

    Drenner, Ray W.

    1977-10-01

    inhaled per minute, was equal to the multiple of the volume of the expanded buccal cavity and the pumping rate. I determined buccal volume by making plaster of Paris molds of the expanded buccal cavity. The volume of the expanded buccal cavity increased...

  8. Optimization of 3D Shape Sharpening Filter Based on Geometric Statistical Values

    E-Print Network [OSTI]

    Tokyo, University of

    is an object created from a mold made from a stone statue, for example, and into which plaster is poured and hardened. The delicate shape is lost, however, during the molding process, and an issue arises have existed for a long period of time, defects and dam- age caused by natural disasters and human

  9. -A Science Servke Feacure Released upon receipt

    E-Print Network [OSTI]

    hurricanes, snowstorms,sand storms, stc. Under this formidable blast trees bend, leaves quiver and the fury- Each drop thus makes a cast of i t s e l f , whichtaining drY flour o r plaster of Paris. is easily

  10. C O R N E L L The Malcolm and Carolyn Wiener Laboratory for U N I V E R S I T Y Aegean and Near Eastern Dendrochronology

    E-Print Network [OSTI]

    Manning, Sturt

    introduced to Janus, the Roman god of gates and doors, endings and beginnings, as shown on this Roman coin of the playwrights Sophocles left and Euripides right from the plaster cast of a double herm in Bonn (H. W. Sage, on the right. DIVI means Divine (thus that Augustus is dead). PP means Pater Patriae (that he was Father of his

  11. DIAGNOSTICS The II pt(Jg*

    E-Print Network [OSTI]

    Fossum, Eric R.

    . The freeze-out of carriers is directly linked to lIfnoise in cryogenic circuits. Thus, GaAs-based circuits area of research in detector electronics centers on implementing cryogenic readout electronics in galli um arsenide (GaAs) materials. GaAs has a lower carrier freeze-out tempera ture than silicon

  12. 892 OPTICS LETTERS / Vol. 14, No. 16 / August 15,1989 Integration of holographic optical elements with polymer gelatin

    E-Print Network [OSTI]

    Chen, Ray

    with polymer gelatin waveguides on GaAs, LiNbO3, glass, and aluminum Ray T. Chen, William Phillips, Thomasz gelatin on GaAs, LiNbO 3 ,glass, and aluminum substrates. Agraded-index profile can be induced in the gelatin layer and tuned by wet processing. This makesit possible to form waveguides on any smooth surface

  13. DEVELOPMENT OF BROADBAND LOW-VOLTAGE RF MEM SWITCHES

    E-Print Network [OSTI]

    Shen, Shyh-Chiang

    DEVELOPMENT OF BROADBAND LOW-VOLTAGE RF MEM SWITCHES S.C. Shen, D. T. Becher, D. C. Caruth, and M)333-4054 Fax: (217) 244-6375 Abstract We present novel RF switches using micro-electro- mechanical (MEM) technology. These MEM switches are built on GaAs substrates using GaAs MESFET MMIC- compatible processes

  14. Date: May 17, 2012 ENI Renewable Energy Prize 2012

    E-Print Network [OSTI]

    Haile, Sossina M.

    junction solar cell efficiencies in thin film GaAs cells. Atwater also co-founded Caelux, Inc, which have pioneered new solar cell designs, including thin GaAs solar cells and Si microwire solar cells Polman of the Dutch Research Institute AMOLF for their research on high-efficiency solar cells based

  15. Journal of Crystal Growth 281 (2005) 209219 Effect of a CuSe secondary phase on the epitaxial

    E-Print Network [OSTI]

    Anderson, Timothy J.

    2005-01-01

    -cost thin-film solar cells. The advantages of this class of materials include their high that appears during epitaxial growth of CuInSe2 (CIS) films on (1 0 0) GaAs substrates was investigated. CIS films with different copper to indium molar ratios were deposited on (1 0 0) GaAs substrates at 360 1C

  16. Semiconductor heterostructures and optimization of light-trapping structures for efficient thin-film solar cells

    E-Print Network [OSTI]

    Yu, Edward T.

    and optimization of light-trapping structures for efficient thin-film solar cells Claiborne O McPheeters1 , Dongzhi elements are integrated for light trapping. Measurements and simulations of GaAs solar cells with less than in their performance. Keywords: quantum-well, quantum-dot, scattering, diffraction, thin-film, GaAs, InAs, photovoltaic

  17. Solar photovoltaics is considered as one of the most promising techniques for supplying clean, sustainable and renewable energy. II-VI and III-V semiconductor materials have attracted

    E-Print Network [OSTI]

    for developing economically viable photovoltaic (PV) thin-film solar cells. Using the approach of multilayer semiconductor quantum dots (QDs) and dilute-nitride GaAsN thin films grown by molecular beam epitaxy (MBE spacer layers grown on GaAs substrates, and dilute-nitride GaAsN thin films grown on GaAs substrates

  18. 1Harry Atwater haa@caltech.edu InterSolar July 9th, 2013 Harry A. Atwater

    E-Print Network [OSTI]

    Wierman, Adam

    , 2013 iPhone cover 1.1 WMan portable charger Single crystal thin film GaAs solar cells and modules ·Cell 9th, 2013 7 Junction Subcell Choices · Single junction ELO cells · lattice-matched to GaAs or In Trapping Filtered Concentrator Alta and Spectrum-splitting III-V Multijunction Solar Cells #12;2Harry

  19. CuInSe2 and its alloys are the leading choice for absorber layers in high-efficiency thin film solar cells due to their direct gap, high absorption coefficient and

    E-Print Network [OSTI]

    Rockett, Angus

    in CuInSe2. Epitaxial CuInSe2 thin films were deposited on GaAs bicrystal substrates using a hybrid film solar cells due to their direct gap, high absorption coefficient and excellent thermal stability epilayers to the GaAs bicrystal substrate. This allows isolation and optical characterization of individual

  20. High optical quality polycrystalline indium phosphide grown on metal substrates by metalorganic chemical vapor deposition

    E-Print Network [OSTI]

    Javey, Ali

    transfer techniques have been explored in the past, where thin epitax- ial films of GaAs and InP and GaAs have the most ideal band gaps and highest the- oretical efficiencies for single-junction cells April 2012; accepted 21 May 2012; published online 25 June 2012) III­V semiconductor solar cells have

  1. Physics 489--Solid State notes for 10/22/2015 Nearly Free Electron Model and Examples; also Tight Binding Model.

    E-Print Network [OSTI]

    Ross, Joseph

    (Ashcroft & Mermin text): 8/cell (Si or GaAs) 3/cell (Aluminum) #12;3 Calculated electron states. 118, 1182 (1960). Below are silicon band structure (on left), and GaAs (right) [LDA calculation, http://th.fhi- berlin.mpg.de/th/fhi98md/doc /main/nod

  2. FEATURE ARTICLE Terahertz Spectroscopy

    E-Print Network [OSTI]

    Se quantum dots. In addition, recent experiments measuring charge transfer in a very direct manner could be generated, propagated through free space, and subsequently detected in the time-domain. Since of semiconductor systems, such as bulk GaAs, low-temperature grown GaAs, nanocrystalline colloidal TiO2, and Cd

  3. Dr. Seth M. Hubbard (a) Professional Preparation

    E-Print Network [OSTI]

    Salvaggio, Carl

    , D. Forbes, "Quantum Dot Spectral Tuning of Multijunction III-V Solar Cells", Mater. Res. Soc. Symp. Aguinaldo, D. Forbes, R. Raffaelle, "InAs Quantum Dot Enhancement of GaAs Solar Cells", Proc. of the 35th of strain compensation on quantum dot enhanced GaAs solar cells", Appl. Phys. Lett. 92, 123512 (2008). 5. C

  4. Monolithic high voltage nonlinear transmission line fabrication process

    DOE Patents [OSTI]

    Cooper, G.A.

    1994-10-04

    A process for fabricating sequential inductors and varistor diodes of a monolithic, high voltage, nonlinear, transmission line in GaAs is disclosed. An epitaxially grown laminate is produced by applying a low doped active n-type GaAs layer to an n-plus type GaAs substrate. A heavily doped p-type GaAs layer is applied to the active n-type layer and a heavily doped n-type GaAs layer is applied to the p-type layer. Ohmic contacts are applied to the heavily doped n-type layer where diodes are desired. Multiple layers are then either etched away or Oxygen ion implanted to isolate individual varistor diodes. An insulator is applied between the diodes and a conductive/inductive layer is thereafter applied on top of the insulator layer to complete the process. 6 figs.

  5. Low-cost, high-efficiency solar cells utilizing GaAs-on-Si technology. Annual subcontract report, 1 August 1991--31 July 1992

    SciTech Connect (OSTI)

    Vernon, S.M.

    1993-04-01

    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.

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

    SciTech Connect (OSTI)

    Vernon, S.M. )

    1993-04-01

    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.

  7. Innovative Clean Coal Technology (ICCT): Demonstration of innovative applications of technology for cost reductions to the CT-121 FGD process. Quarterly report No. 6, July--September 1991

    SciTech Connect (OSTI)

    Not Available

    1991-11-15

    The project`s objective is to demonstrate innovative applications of technology for cost reduction for the Chiyoda Thoroughbred-121 (CT-121) process. The CT-121 process is a wet FGD process that removes SO{sub 2}, can achieve simultaneous particulate control, and can produce a salable by-product gypsum thereby reducing or even eliminating solid waste disposal problems. Figure 1 shows a flow schematic of the process. CT-121 removes SO{sub 2} and particulate matter in a unique limestone-based scrubber called the Jet Bubbling Reactor (JBR). IN the JBR, flue gas bubbles beneath the slurry, SO{sub 2} is absorbed, and particulate matter is removed from the gas. The agitator circulates limestone slurry to ensure that fresh reactant is always available in the bubbling or froth zone sot that SO{sub 2} removal can proceed at a rapid rate. Air is introduced into the bottom of the JBR to oxidize the absorbed SO{sub 2} to sulfate, and limestone is added continuously to neutralize the acid slurry and form gypsum. The JBR is designed to allow ample time for complete oxidation of the SO{sub 2}, for complete reaction of the limestone, and for growth of large gypsum crystals. The gypsum slurry is continuously withdrawn from the JBR and is to be dewatered in a gypsum stack. The stacking technique involves filing a diked area with gypsum slurry, allowing the gypsum solids to settle, and removing clear liquid from the top of the stack for recycle back to the process.

  8. Atomistic description of the electronic structure of InxGa1xAs alloys and InAsGaAs superlattices

    E-Print Network [OSTI]

    Kent, Paul

    quantum-wells15,20 (InxGa1 xAs)n /InP on InP and (InxGa1 xAs)n /GaAs on GaAs, and v GaAs-embedded InAs quantum dots.21­23 We wish to provide a uniform the- oretical description of the electronic structure-period dependence of the band offsets and interband transitions of InAs/GaAs systems on InP and GaAs substrates. DOI

  9. DEDALOS NREL: Cooperative Research and Development Final Report, CRADA Number CRD-07-237

    SciTech Connect (OSTI)

    Friedman, D.

    2013-06-01

    Currently High Concentration Photovoltaic (HCPV) terrestrial modules are based on the combination of optic elements that concentrate the sunlight into much smaller GaAs space cells to produce electricity. GaAs cell technology has been well developed for space applications during the last two decades, but the use of GaAs cells under concentrated sunlight in terrestrial applications leaves unanswered questions about performance, durability and reliability. The work to be performed under this CRADA will set the basis for the design of high-performance, durable and reliable HCPV terrestrial modules that will bring down electricity production costs in the next five years.

  10. Fabrication of Semiconductors by Wet Chemical Etch

    E-Print Network [OSTI]

    Francoviglia, Laura

    2008-07-01

    AlGaAs not intentionally doped (i) 130 Å InGaAs not intentionally doped (i) 30 Å AlGaAs not intentionally doped (i) Delta Si Doping 1.1E12/cm2 Superlattice Buffer GaAs Buffer S.I. GaAs Substrate Epi Layer Structures of V3339 350 Å GaAs 5E18 Si Doping... with Bardeen, Brittain and Shockley’s invention of the transistor in Bell Labs in 1947 and Kilby and Noyce’s introduction of the integrated circuit about a decade later, semiconductor devices have dramat- ically advanced the computing and electronics...

  11. Macroscopic corrosion front computations of sulfate attack in sewer pipes based on a micro-macro reaction-diffusion model

    E-Print Network [OSTI]

    Chalupecký, Vladimír; Kruschwitz, Jens; Muntean, Adrian

    2012-01-01

    We consider a two-scale reaction diffusion system able to capture the corrosion of concrete with sulfates. Our aim here is to define and compute two macroscopic corrosion indicators: typical pH drop and gypsum profiles. Mathematically, the system is coupled, endowed with micro-macro transmission conditions, and posed on two different spatially-separated scales: one microscopic (pore scale) and one macroscopic (sewer pipe scale). We use a logarithmic expression to compute values of pH from the volume averaged concentration of sulfuric acid which is obtained by resolving numerically the two-scale system (microscopic equations with direct feedback with the macroscopic diffusion of one of the reactants). Furthermore, we also evaluate the content of the main sulfatation reaction (corrosion) product---the gypsum---and point out numerically a persistent kink in gypsum's concentration profile. Finally, we illustrate numerically the position of the free boundary separating corroded from not-yet-corroded regions.

  12. Advanced Flue Gas Desulfurization (AFGD) demonstration project: Volume 2, Project performance and economics. Final technical report

    SciTech Connect (OSTI)

    1996-04-30

    The project objective is to demonstrate removal of 90--95% or more of the SO{sub 2} at approximately one-half the cost of conventional scrubbing technology; and to demonstrate significant reduction of space requirements. In this project, Pure Air has built a single SO{sub 2} absorber for a 528-MWe power plant. The absorber performs three functions in a single vessel: prequencher, absorber, and oxidation of sludge to gypsum. Additionally, the absorber is of a co- current design, in which the flue gas and scrubbing slurry move in the same direction and at a relatively high velocity compared to conventional scrubbers. These features all combine to yield a state- of-the-art SO{sub 2} absorber that is more compact and less expensive than conventional scrubbers. The project incorporated a number of technical features including the injection of pulverized limestone directly into the absorber, a device called an air rotary sparger located within the base of the absorber, and a novel wastewater evaporation system. The air rotary sparger combines the functions of agitation and air distribution into one piece of equipment to facilitate the oxidation of calcium sulfite to gypsum. Additionally, wastewater treatment is being demonstrated to minimize water disposal problems inherent in many high-chloride coals. Bituminous coals primarily from the Indiana, Illinois coal basin containing 2--4.5% sulfur were tested during the demonstration. The Advanced Flue Gas Desulfurization (AFGD) process has demonstrated removal of 95% or more of the SO{sub 2} while providing a commercial gypsum by-product in lieu of solid waste. A portion of the commercial gypsum is being agglomerated into a product known as PowerChip{reg_sign} gypsum which exhibits improved physical properties, easier flowability and more user friendly handling characteristics to enhance its transportation and marketability to gypsum end-users.

  13. A field evaluation of the movement of selected metals in revegetated strip mine overburden and laboratory assessment of transport mechanisms 

    E-Print Network [OSTI]

    Launius, Kenneth Wayne

    1980-01-01

    placement of materials following the excavation and sampling of lignite at a test pit. The effect of varying ratios of lime and gypsum had on revegetation were studied. Resultant overburden'pH and electrical conductivity (EC) wire evaluated... and gypsum have on pH, electr 1cal conductiv1ty (EC) and bermudagrass yield, Lime requirement ( LR) was determ1ned on a sample of the overburden from the test pit. One, 2, 4, 8, j6 and 32 meq of reagent grade CaCO, were mixed wi th 1ndividual IOD g...

  14. Comparison of steady-state and transient characteristics of lattice-matched and strained InGaAs-AlGaAs (on GaAs) and InGaAs-AlInAs (on InP) quantum-well lasers

    SciTech Connect (OSTI)

    Lam, Y.; Singh, J. ); Loehr, J.P. )

    1992-05-01

    This paper reports on numerical techniques to study the output spectra and to solve the multimode coupled rate equations including TE and TM propagations for In{sub x}Ga{sub 1{minus}x}As-Al{sub 0.3}Ga{sub 0.7}As and In{sub 0.53+x}Ga{sub 0.47{minus}x}As-Al{sub 0.48}In{sub 0.52}As quantum well lasers. Optical properties are calculated from a 4 {times} 4 k {center dot} p bandstructure and strain effects are included with the deformation potential theory. The authors find that an introduction of 1.4% compressive strain to the quantum well results in roughly 3-4 times improvement in the intrinsic static characteristics in terms of lower threshold current, greater mode suppression, and lower nonlashing photon population in the laser cavity. The authors also identify the role of strain on the large signal temporal response. If the laser is switched from the off state to a given photon density in the lasing mode, then the strained system exhibits a faster intrinsic time response. However, if the lasers are switched to equal total photon density, then the strained system has a slower time response. The authors also include calculated CHSH Auger rates in our model and find that the main effect of Auger recombination is to greatly increase the threshold current and to shorten the response time to large signal switching.

  15. In-situ deposition of high-k dielectrics on III-V compound semiconductor in MOCVD system

    E-Print Network [OSTI]

    Cheng, Cheng-Wei, Ph.D. Massachusetts Institute of Technology

    2010-01-01

    In situ deposition of high-k materials to passivate the GaAs in metal organic chemical vapor deposition (MOCVD) system was well demonstrated. Both atomic layer deposition (ALD) and chemical vapor deposition (CVD) methods ...

  16. Fabrication of optical structures using SU-8 photoresist and chemically assisted ion beam

    E-Print Network [OSTI]

    Fainman, Yeshaiahu

    transferred into an chemical vapor deposition CVD grown SiO2 layer, evaporated or electroplated metal layers in a SU-8 layer spin coated onto the surface of GaAs substrate is performed using a contact print

  17. Metallic nanostructures for optoelectronic and photovoltaic applications

    E-Print Network [OSTI]

    Lim, Swee Hoe

    2009-01-01

    ultrathin film high efficiency solar cells by nanostructureproposed for very high efficiency solar cells 4,5 . Detailthe 300nm GaAs solar cell quantum efficiency as a function

  18. bottom board mother board

    E-Print Network [OSTI]

    Tentzeris, Manos

    the radio spectrum even further in the near future. Current trends have placed an ever-increasing demand can be engineered to match copper, silicon or GaAs, thereby making metallization on it easier. LCP

  19. Hybrid solar collector using nonimaging optics and photovoltaic components

    E-Print Network [OSTI]

    2015-01-01

    thermal hybrid solar technology," Applied Energy, 87(2),thermal hybrid solar technology," Applied Energy, 87(2),thermal system, solar PVT collector, nonimaging optics, GaAs, solar energy,

  20. Efficient Sensor Node Authentication via 3GPP Mobile Communication Networks

    E-Print Network [OSTI]

    Kim, Kwangjo

    , 3G-WSN 1. INTRODUCTION As a de facto standard for the wireless sensor networks (WSNs), Zigbee [3 smartphone as a mobile device (MD) has GAA module and Zigbee module. The network consists of mobile network

  1. Sandia Energy - EC Publications

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

    fabrication of micro-scale crystalline silicon and GaAs solar cells, the release of these cells into a photovoltaic (PV) "ink" solution, and the printing of these cells onto a...

  2. Charge detection in semiconductor nanostructures

    E-Print Network [OSTI]

    MacLean, Kenneth (Kenneth MacLean, III)

    2010-01-01

    In this thesis nanometer scale charge sensors are used to study charge transport in two solid state systems: Lateral GaAs quantum dots and hydrogenated amorphous silicon (a-Si:H). In both of these experiments we use ...

  3. Optimized Designs and Materials for Nanostructure Based Solar Cells

    E-Print Network [OSTI]

    Shao, Qinghui

    2009-01-01

    InGaAs triple-junction solar cells grown inverted with abonded GaAs/InGaAs tandem solar cell,” Appl. Phys. Lett. 89,2 /GaAs tandem-junction solar cells,” Appl. Phys. Lett. 83,

  4. Nanopillar Photovoltaics: Photon Management and Junction Engineering for Next-Generation Solar Cells

    E-Print Network [OSTI]

    Mariani, Giacomo

    2013-01-01

    Towards efficient hybrid solar cells based on fully polymerSariciftci, N. S. Hybrid solar cells, Inorg. Chim. Acta 361,radial GaAs nanopillar solar cells, Nano Lett. 11, 2490-

  5. Nanopillar Photovoltaics: Photon Management and Junction Engineering for Next-Generation Solar Cells

    E-Print Network [OSTI]

    Mariani, Giacomo

    2013-01-01

    S. Heterojunction photovoltaics using GaAs nanowires andC. M. Single nanowire photovoltaics, Chem. Soc. Rev. 38, 16-nanopillar-array photovoltaics on low-cost and flexible

  6. Outdoor Performance of a Thin-Film Gallium-Arsenide Photovoltaic Module

    SciTech Connect (OSTI)

    Silverman, T. J.; Deceglie, M. G.; Marion, B.; Cowley, S.; Kayes, B.; Kurtz, S.

    2013-06-01

    We deployed a 855 cm2 thin-film, single-junction gallium arsenide (GaAs) photovoltaic (PV) module outdoors. Due to its fundamentally different cell technology compared to silicon (Si), the module responds differently to outdoor conditions. On average during the test, the GaAs module produced more power when its temperature was higher. We show that its maximum-power temperature coefficient, while actually negative, is several times smaller in magnitude than that of a Si module used for comparison. The positive correlation of power with temperature in GaAs is due to temperature-correlated changes in the incident spectrum. We show that a simple correction based on precipitable water vapor (PWV) brings the photocurrent temperature coefficient into agreement with that measured by other methods and predicted by theory. The low operating temperature and small temperature coefficient of GaAs give it an energy production advantage in warm weather.

  7. Multi-spectral optical absorption in substrate-free nanowire arrays

    SciTech Connect (OSTI)

    Zhang, Junpeng; Chia, Andrew; Boulanger, Jonathan; LaPierre, Ray; Dhindsa, Navneet; Khodadad, Iman; Saini, Simarjeet

    2014-09-22

    A method is presented of fabricating gallium arsenide (GaAs) nanowire arrays of controlled diameter and period by reactive ion etching of a GaAs substrate containing an indium gallium arsenide (InGaP) etch stop layer, allowing the precise nanowire length to be controlled. The substrate is subsequently removed by selective etching, using the same InGaP etch stop layer, to create a substrate-free GaAs nanowire array. The optical absorptance of the nanowire array was then directly measured without absorption from a substrate. We directly observe absorptance spectra that can be tuned by the nanowire diameter, as explained with rigorous coupled wave analysis. These results illustrate strong optical absorption suitable for nanowire-based solar cells and multi-spectral absorption for wavelength discriminating photodetectors. The solar-weighted absorptance above the bandgap of GaAs was 94% for a nanowire surface coverage of only 15%.

  8. band density of states whereas the higher energy side is deter-mined by the thermal distribution. With increasing tem-

    E-Print Network [OSTI]

    Chen, Sheng

    . wavelength, pm ~ Fig. 4 Demonstration ofthe application ofan InAs, -.Sb, light emitting diode as a CO, sensor light emitting diodes on GaAs or Si substrates. The devices readily result in a new generation of infra

  9. 66 NATURE PHYSICS | VOL 9 | FEBRUARY 2013 | www.nature.com/naturephysics news & views

    E-Print Network [OSTI]

    Loss, Daniel

    with first principles calculations -- will help to develop quantum-dot devices with stable hole- spin states confinement in materials such as InP and GaAs, which are commonly found in today's optoelectronic devices

  10. Superficies y Vaco 12, 39-44, Junio 2001 Sociedad Mexicana de Ciencia de Superficies y de Vaco. *Corresponding author, e-mail: mlopez@fis.cinvestav.mx

    E-Print Network [OSTI]

    Meléndez Lira, Miguel Angel

    impurezas, desorden en las aleaciones, rugosidad en las interfaces, etc. Estos aspectos dependen fuertemente dependen del tipo de proceso de interrupción realizado en la capa colchón de GaAs. Se calculó la rugosidad

  11. Technical Session II Talks | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    .pdf file (6.2MB) GaAs Detector (Durbin) .pdf file (450KB) Advanced Neutron Detectors (Smith) .pdf file (818KB) Neutron Imaging System (Bingham) .pdf file (1.1MB) SR Advanced...

  12. Tuning of Spin Dependent Reflection at Ferromagnet/GaAs Interfaces

    E-Print Network [OSTI]

    Li, Yan

    2010-01-01

    In this mix, graphene is a zero gap semiconductor and spinsemiconductors have been realized on GaAs [24, 32], Si [33-35], Graphene [graphene has also been realized. 1.3.1 Spin injection into semiconductors

  13. Near-unity broadband absorption designs for semiconducting nanowire arrays via localized

    E-Print Network [OSTI]

    Atwater, Harry

    for Artificial Photosynthesis, California Institute of Technology, Pasadena, CA 91125, USA 3 Department analysis and modeling of light trappig in high efficiency GaAs nanowire array solar cells," Appl. Phys

  14. Crystalline phases of II-VI compound semiconductors grown by pulsed laser deposition

    E-Print Network [OSTI]

    Kwok, Hoi S.

    and 100 InP and GaAs substrates by PLD in this study. A clean stainless steel vacuum chamber . There was no annealing performed on the tar- get. Substrates were cut from single-crystal wafers and cleaned

  15. Monolithic heteroepitaxial integration of III-V semiconductor lasers on Si substrates

    E-Print Network [OSTI]

    Groenert, Michael

    2002-01-01

    Monolithic optoelectronic integration on silicon-based integrated circuits has to date been limited to date by the large material differences between silicon (Si) and the direct-bandgap GaAs compounds from which optoelectronic ...

  16. Structure and electrical characterization of gallium arsenide nanowires with different V/III ratio growth parameters

    SciTech Connect (OSTI)

    Muhammad, R.; Ahamad, R.; Ibrahim, Z.; Othaman, Z.

    2014-03-05

    Gallium arsenide (GaAs) nanowires were grown vertically on GaAs(111)B substrate by gold-assisted using metal-organic chemical vapour deposition. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and conductivity atomic force microscopy (CAFM) analysis were carried out to investigate the effects of V/III ratio on structural properties and current-voltage changes in the wires. Results show that GaAs NWs grow preferably in the wurtzite crystal structure than zinc blende crystal structure with increasing V/III ratio. Additionally, CAFM studies have revealed that zincblende nanowires indicate ohmic characteristic compared to oscillation current occurred for wurtzite structures. The GaAs NWs with high quality structures are needed in solar cells technology for trapping energy that directly converts of sunlight into electricity with maximum capacity.

  17. Fabrication of Molecular Devices 

    E-Print Network [OSTI]

    Walton, Katherine

    2011-08-04

    and dithiols were prepared on Au and GaAs surfaces. There chemical assembly was investigated using a combination of Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). The surface morphology and nanopatterning of these SAMs...

  18. pp: 1-6 (col.fig.: Nil) PROD. TYPE: COM PAGN: Murthy.N --SCAN: Shubha

    E-Print Network [OSTI]

    Ganichev, Sergey

    temperature. Two pairs of ohmic contacts have been centered along opposite sample edges. For 45 optical 3)-grown GaAs QWs of Cs symmetry normalized by the light power P as a function of the phase angle

  19. TOKAMAK REACTOR DESIGNS AS A FUNCTION OF ASPECT RATIO

    E-Print Network [OSTI]

    California at Los Angeles, University of

    GA­A23168 TOKAMAK REACTOR DESIGNS AS A FUNCTION OF ASPECT RATIO by C.P.C. WONG and R.D. STAMBAUGH or reflect those of the United States Government or any agency thereof. #12;GA­A23168 TOKAMAK REACTOR DESIGNS JULY 1999 #12;C.P.C. WONG AND R.D. STAMBAUGH TOKAMAK REACTOR DESIGNS AS A FUNCTION OF ASPECT RATIO

  20. Reply to “Comment on ‘Optically pumped spin-exchange polarized-electron source’ ”

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

    Pirbhai, M.; Knepper, J.; Litaker, E. T.; Tupa, D.; Gay, T. J.

    2015-05-26

    In the proceeding Comment [1] on our recent report of a Rb spin-exchange polarized-electron source [2], Williams et al. contend: (a) that our source is poorly characterized compared with modern GaAs sources, (b) that we have overstated the difficulties of using GaAs photoemission sources, and (c) that our explanation of various physics issues related to the source's operating principles are not cogent.

  1. Towards vertical III-V nanowire devices on silicon Erik P.A.M. Bakkers, Magnus T. Borgstrom, Wim van den Einden, Maarten van Weert, Ethan D. Minot,

    E-Print Network [OSTI]

    AsP quantum dot region can be incorporated into these devices.4 The axial geometry allows for controllable in the investigation of semiconductor materials that intrinsically have higher mobilities, such as GaAs, InP, and In. It is shown that GaP, GaAs, InP and InAs can be grown on silicon with a lattice mismatch ranging between 0

  2. First-principles calculation of the bulk photovoltaic effect in the polar compounds LiAsS2, LiAsSe2, and NaAsSe2

    E-Print Network [OSTI]

    Rappe, Andrew M.

    by the AIP Publishing Articles you may be interested in (Sr,Ba)(Si,Ge)2 for thin-film solar-cell applications effects on atomic bonding and electronic properties at HfO2/GaAs interface: A first-principles study J.g., Si, CdTe, CIGS, and GaAs), in order for a material to exhibit a signif- icant BPVE response from

  3. High Quality Epitaxial Growth of GaAsyP1-y Alloys on Si1-xGex Virtual P. Sharma, M. T. Bulsara, and E. A. Fitzgerald

    E-Print Network [OSTI]

    in an appropriate temperature window, could produce high-quality GaAs thin films on Ge. Over a range of growth, tandem solar cell designs on Si. Despite the lattice-matched condition of GaP on Si, low defect density less than 106 /cm2 ) has not been reported in the literature [1-4]. In contrast, the analogous GaAs

  4. NEUTRON WALL LOADING OF TOKAMAK REACTORS

    E-Print Network [OSTI]

    California at Los Angeles, University of

    GA­A23223 NEUTRON WALL LOADING OF TOKAMAK REACTORS by C.P.C. WONG OCTOBER 1999 #12;DISCLAIMER Government or any agency thereof. #12;GA­A23223 NEUTRON WALL LOADING OF TOKAMAK REACTORS by C.P.C. WONG by General Atomics IR&D Funds GA PROJECT 4437 OCTOBER 1999 #12;C.P.C. WONG NEUTRON WALL LOADING OF TOKAMAK

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

    SciTech Connect (OSTI)

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

    2005-11-01

    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.

  6. Carbon doping of III-V compound semiconductors

    SciTech Connect (OSTI)

    Moll, A.J.

    1994-09-01

    Focus of the study is C acceptor doping of GaAs, since C diffusion coefficient is at least one order of magnitude lower than that of other common p-type dopants in GaAs. C ion implantation results in a concentration of free holes in the valence band < 10% of that of the implanted C atoms for doses > 10{sup 14}/cm{sup 2}. Rutherford backscattering, electrical measurements, Raman spectroscopy, and Fourier transform infrared spectroscopy were amonth the techniques used. Ga co-implantation increased the C activation in two steps: first, the additional radiation damage creates vacant As sites that the implanted C can occupy, and second, it maintains the stoichiometry of the implanted layer, reducing the number of compensating native defects. In InP, the behavior of C was different from that in GaAs. C acts as n-type dopant in the In site; however, its incorporation by implantation was difficult to control; experiments using P co-implants were inconsistent. The lattice position of inactive C in GaAs in implanted and epitaxial layers is discussed; evidence for formation of C precipitates in GaAs and InP was found. Correlation of the results with literature on C doping in III-V semiconductors led to a phenomenological description of C in III-V compounds (particularly GaAs): The behavior of C is controlled by the chemical nature of C and the instrinsic Fermi level stabilization energy of the material.

  7. The comparison between gallium arsenide and indium gallium arsenide as materials for solar cell performance using Silvaco application

    SciTech Connect (OSTI)

    Zahari, Suhaila Mohd; Norizan, Mohd Natashah; Mohamad, Ili Salwani; Osman, Rozana Aina Maulat; Taking, Sanna

    2015-05-15

    The work presented in this paper is about the development of single and multilayer solar cells using GaAs and InGaAs in AM1.5 condition. The study includes the modeling structure and simulation of the device using Silvaco applications. The performance in term of efficiency of Indium Gallium Arsenide (InGaAs) and GaAs material was studied by modification of the doping concentration and thickness of material in solar cells. The efficiency of the GaAs solar cell was higher than InGaAs solar cell for single layer solar cell. Single layer GaAs achieved an efficiency about 25% compared to InGaAs which is only 2.65% of efficiency. For multilayer which includes both GaAs and InGaAs, the output power, P{sub max} was 8.91nW/cm² with the efficiency only 8.51%. GaAs is one of the best materials to be used in solar cell as a based compared to InGaAs.

  8. CEMENT RELATED RESEARCH HYDROGEOCHEMISTRY GROUP

    E-Print Network [OSTI]

    Politècnica de Catalunya, Universitat

    CEMENT RELATED RESEARCH HYDROGEOCHEMISTRY GROUP Josep M. Soler Jordi Cama Carles Ayora Ana Trapote.soler@idaea.csic.es #12;NOMECLATURE cement + water = hardened cement paste cement + water + sand = mortar cement + waterC) clinker + gypsum portland cement PORTLAND CEMENT #12;GTS-HPF Core Infiltration Experiment Experimental

  9. Irrigation and Management of Texas Soils. 

    E-Print Network [OSTI]

    Box, John; Bennett, William F.

    1959-01-01

    are of two types - those pro- viding soluble calcium such as gypsum, and acid or acid-forming amendments such as sul- fur, sulfuric acid, iron sulfate and aluminium sulfate. Application of limestone may be valu- able as a source of calcium on acid soils...

  10. Digital Fabrication Lab (Fab-Lab) Handbook F2010

    E-Print Network [OSTI]

    Papalambros, Panos

    Prototyping 3D printer ZCorp Z403 Rapid Prototyping 3D printer Prints 3D gypsum or starch models from digital.The submission process for 3d printing is outlined in the section below on 3d printing. Scheduling, equipment Mills 3D surfaces out of solid materials and cuts 2D profiles of flat stock materials. www

  11. Evaluation of the heterotic potential of sorghum [Sorghum bicolor (L.) Moench] adapted to the southern Africa region 

    E-Print Network [OSTI]

    Mpofu, Leo Thokoza

    2007-04-25

    -mold sands, charcoal briquets and oil well mud. Sorghum flour is used in the manufacture of plywood and gypsum to build houses as well as in the refining process of potash and aluminum. When used as a feed grain, the relative feed value of sorghum is 96...

  12. Spencer_Answers to student questions 415.pdf Student questions: Jon Spencer colloquium on "The Pliocene Bouse Formation and Initiation

    E-Print Network [OSTI]

    Rhoads, James

    , the basin areas around the Colorado river and Salt River appear visually similar. Did similar geology happen table. If evaporation concentrates salt (halite) and gypsum, it will concentrate strontium of the Colorado River valley, and cited the volcanic/tectonic activity as a contra indicator to that idea. Could

  13. Oxidation and characterization of FGD byproduct calcium sulfite and oxidized product 

    E-Print Network [OSTI]

    Gupta, Anurag

    1993-01-01

    . . . . . Production of Calcium Sulfate Hemihydrate. . . , . Utilization of FGD Byproduct Gypsum. . . . . . . . . . . 5 6 8 9 11 12 12 18 19 20 22 EXPERIMENTAL TECHNIQUES. . . . . 23 Characterization of the FGD Byproduct. . . . . . 23 Thermal Analysis.... . . . . X-ray Diffraction Results. Infrared Spectroscopy Results. . . . . Thermal Analysis Results. . . . . . . . . . . Particles Morphology Characterization and Stability of the Sulfite Phase. . . . . . Oxidation of Calcium Sulfite Slurries...

  14. U.S. Department of the Interior U.S. Geological Survey

    E-Print Network [OSTI]

    Torgersen, Christian

    Graphite Peat Talc Beryllium Gypsum Perlite Tantalum Bismuth Hafnium Phosphate Rock Tellurium Boron Helium information on the USGS--the Federal source for science about the Earth, its natural and living resources--Reserves and Resources.....................193 Appendix D--Country Specialists Directory...............198 Mineral

  15. Iron and Steel Phosphate Rock

    E-Print Network [OSTI]

    Torgersen, Christian

    Kyanite Lead Lime Lithium Magnesium Manganese Mercury Mica Molybdenum Nickel Nitrogen Peat Perlite Graphite Peat Sulfur Beryllium Gypsum Perlite Talc Bismuth Hafnium Phosphate Rock Tantalum Boron Helium on the USGS--the Federal source for science about the Earth, its natural and living resources, natural hazards

  16. MINERAL COMMODITY SUMMARIES 2014

    E-Print Network [OSTI]

    Torgersen, Christian

    Talc Bauxite Graphite Peat Tantalum Beryllium Gypsum Perlite Tellurium Bismuth Hafnium Phosphate Rock resources, natural hazards, and the environment-- visit http://www.usgs.gov or call 1­888­ASK--Reserves and Resources.....................191 Appendix D--Country Specialists Directory...............195 Mineral

  17. Iron and Steel Phosphate Rock

    E-Print Network [OSTI]

    Torgersen, Christian

    Kyanite Lead Lime Lithium Magnesium Manganese Mercury Mica Molybdenum Nickel Nitrogen Peat Perlite Graphite Peat Sulfur Beryllium Gypsum Perlite Talc Bismuth Hafnium Phosphate Rock Tantalum Boron Helium information on the USGS--the Federal source for science about the Earth, its natural and living resources

  18. Iron and Steel Phosphate Rock

    E-Print Network [OSTI]

    Torgersen, Christian

    Kyanite Lead Lime Lithium Magnesium Manganese Mercury Mica Molybdenum Nickel Nitrogen Peat Perlite Niobium Stone Barite Gold Nitrogen Strontium Bauxite Graphite Peat Sulfur Beryllium Gypsum Perlite Talc, its natural and living resources, natural hazards, and the environment: World Wide Web: http

  19. MINERAL COMMODITY SUMMARIES 2012

    E-Print Network [OSTI]

    Fleskes, Joe

    Nitrogen Sulfur Bauxite Graphite Peat Talc Beryllium Gypsum Perlite Tantalum Bismuth Hafnium Phosphate Rock and living resources, natural hazards, and the environment-- visit http://www.usgs.gov or call 1­888­ASK--Reserves and Resources.....................193 Appendix D--Country Specialists Directory...............197 Mineral

  20. U.S. Department of the Interior U.S. Geological Survey

    E-Print Network [OSTI]

    Fleskes, Joe

    Graphite Peat Talc Beryllium Gypsum Perlite Tantalum Bismuth Hafnium Phosphate Rock Tellurium Boron Helium information on the USGS--the Federal source for science about the Earth, its natural and living resources--Reserves and Resources.....................193 Appendix D--Country Specialists Directory...............197 Mineral

  1. Oil and Gas Exploration

    E-Print Network [OSTI]

    Tingley, Joseph V.

    , oil and gas, and geothermal activities and accomplishments in Nevada: production statistics Products 23. Sloan dolomite quarry 24. Weiser gypsum quarry Oil Fields 1. Blackburn field 2. North WillowMetals Industrial Minerals Oil and Gas Geothermal Exploration Development Mining Processing Nevada

  2. Daylighting techniques used in indigenous buildings in the United Arab Emirates (UAE), an investigative approach 

    E-Print Network [OSTI]

    Alnuaimi, Maitha Mohammed

    2009-06-02

    the space. Desktop Radiance 2.0 Beta was used as the lighting performance analysis tool under clear sky conditions. Results have shown that the gypsum decorative panel performs better than the other two systems in terms of light uniformity and distribution...

  3. DOI: 10.1126/science.1215648 , 69 (2012);336Science

    E-Print Network [OSTI]

    Benning, Liane G.

    2012-01-01

    anti-scaling strategies for water desalination and may help to explain the persistence of CaSO4 phases, and anhydrite) from seawater led to the formation of numerous ancient and modern evaporite deposits on Earth (1 equipment in desalination plants that produce drinking water (5, 6). The formation of gypsum (CaSO4·2H2O

  4. 9 1989by The Humana Press Inc. All rights of any nature whatsoever reserved.

    E-Print Network [OSTI]

    California at Riverside, University of

    E. WYMAN Solar Energy Research Institute, 1617 Cole Boulevard, Golden, CO 80401 ABSTRACT, and xylose. A liquid stream, containing xylose, is separated from a cellulose/lignin stream, and the liquid stream is then neutralized. After removing gypsum, the neutralized xylose stream is ready for further

  5. Appendix B: Wastes and Potential Hazards for

    E-Print Network [OSTI]

    Siddharthan, Advaith

    of minerals including gypsum, salt, potash, asbestos, graphite, fluorite, calcite, clay, sand and gravel or their compounds and should be considered under the following hazards: H5 to H7, H10, H11, or H14. 01 05 drilling muds and other drilling wastes 01 05 05* oil-containing drilling muds and wastes M Oil-containing muds

  6. TUDE EXPRIMENTALE D'UN CALODUC AVEC SUBSTANCE POREUSE ACTIVE

    E-Print Network [OSTI]

    Boyer, Edmond

    In view of a solar application a heat pipe at a reduced scale of dimensions of 60 mm, external diameter and 267 mm, length is studied. In order that the heat pipe be independent of its inclinations an active porous medium is used within it. Gypsum is used as a porous medium for the heat pipe for the reason

  7. Extremely acidic, pendulous cave wall biofilms from the Frasassi cave system, Italy

    E-Print Network [OSTI]

    Macalady, Jenn

    on either side of the Frasassi gorge. Based on uranium series dating of carbonate speleothems, the highest deposits throughout the upper levels of the cave are analogous to gypsum crusts currently forming and depositing in the lowest level, sug- gesting a similar mode of cave formation throughout the history

  8. ANNUAL HEATING AND COOLING REQUIREMENTS AND DESIGN DAY PERFORMANCE FOR A RESIDENTIAL MODEL IN SIX CLIMATES: A COMPARISON OF NBSLD, BLAST 2, AND DOE-2.1

    E-Print Network [OSTI]

    Carroll, William L.

    2011-01-01

    Board I-F-Rd Wood Siding Sheathing 2X4 Stud Gypsum Board I-A3/8-IN-WOOD-SlDING A1/2-IN-SHEATHING A2X4-STUD Al/2-IN-A3/8-IN-WOOD~SIDING Al/2-IN-SHEATHING A2X4-STUD Al /2-IN-

  9. Field Devices for Monitoring Soil Water Content

    E-Print Network [OSTI]

    (ADR): Impedance 2.1.2.4. Phase Transmission 2.1.2.5. Time Domain Transmission (TDT) 2.1.3. Other.2.2.1. Gypsum (Bouyoucos) Block 2.2.2.2. Granular Matrix Sensors (GMS) 2.2.3. Heat Dissipation 2.2.4. Soil

  10. Texas Soils: A Study of Chemical Composition. 

    E-Print Network [OSTI]

    Harrington, H. H. (Henry Hill)

    1892-01-01

    suils, are examples of the benefit act ing from a full supply of lime. Or, let US take sulphuric acid. ? is of course combined as some salt. For example, sulphate of pot2 sulphate of lime (gypsum), snlphate of ammonia (in fertilizers), sulphate... ..................... Alumina Oxide.. Calcium Oxide ....................... .................... Magnesium Oxide. ....................... Aulphuric Arid. .................... Phusphoric Acid. ............................. Potash Soda...

  11. Predicting Rock Mass Decay in Engineering Lifetimes

    E-Print Network [OSTI]

    Hack, Robert

    GEORGE KENNETH HACK International Institute for Geo-Information Science and Earth Observation, P.O. Box 6 of fieldwork by the International Institute for Geo-Information Science and Earth Observation and Delft. In soluble materials such as the gypsum unit investigated here, water retention in slopes sheltered from

  12. Atmos. Chem. Phys., 10, 11831192, 2010 www.atmos-chem-phys.net/10/1183/2010/

    E-Print Network [OSTI]

    Meskhidze, Nicholas

    Hydro Method (OHM). The pulverized coal, bottom ash, fly ash and gypsum were also sampled in the field may then be oxidized by HCl, SO2, and fly ash in flue gas due to thermo-chemical processes (Meij et al speciation in flue gas right after the boiler is in- fluenced by the contents of halogen, mercury, and ash

  13. Commercial Fertilizers in 1934-35. 

    E-Print Network [OSTI]

    Fraps, G. S. (George Stronach); Asbury, S. E. (Samuel E.)

    1935-01-01

    Food 9 Relation of Cost to Concentration of Fertilizer ._----_-__------------------ 11 Comparing Costs of Fertilizer ._----___------------------- 12 Free Analysis 12 Fertilizer Analyses to be Sold in 19 3 5-3 6... ...................................... 13 Analysis of Fertilizers, 19 3 4-3 5 ....................................... 13 Averages Below Guarantee 14 Investigations Under the Fertilizer Law 14 Relation to Experiment Station Work 15 Colloidal Mineral Phosphate 15 Sulphur, Gypsum...

  14. Standard Room Fire Test Research at the National Bureau of Standards 

    E-Print Network [OSTI]

    Lee, B.T.; Steel, J.S.

    , and gypsum board. Three 900 s duration test scenarios were considered. Scenario A is a constant 180 kW ignition source exposure. Scenario B achieves the same maximum exposure after three intervals of 30 s each in which the heat release rate is increased...

  15. Three-dimensional fracture and fragmentation of artificial kidney stones This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Ortiz, Michael

    Three-dimensional fracture and fragmentation of artificial kidney stones This article has been IOPscience #12;Three-dimensional fracture and fragmentation of artificial kidney stones Alejandro Mota1 Laboratory Livermore, CA 94550, USA July 25, 2006 Abstract The brittle fracture of a gypsum cylinder, which

  16. Elden Tefft: An Informal Look at a Founding Father of Twentieth Century Bronze Casting in the United States

    E-Print Network [OSTI]

    Voorhees, Craig

    2011-07-29

    in and the surface of the bronze is cooler than its hot core. This causes the bronze to shrink unevenly as it cools down and distorts the original shape given to it by the mold. Even something as small as the brick sized ingots that bronze sculptors get from... material", mixing it up and pouring the plaster into "flasks" that have to be built, "cups" carved out of the molds and, of course, clean up. I hung around Elden's studio after my sword furniture was finished and another sculptor who works out...

  17. Advanced Mechanical Heat Pump Technologies for Industrial Applications 

    E-Print Network [OSTI]

    Mills, J. I.; Chappell, R. N.

    1985-01-01

    seven fins per inch are used. The excijangers utilize modular cores consisting/of thirty 5/8-in.-diameter x 48-in.!10n g tubes per row, eight rows deep. Oucting walls, which contain the air/sol ent mixture, are stainless steel. A rofin... HEAT PUMP TECHNOLOGIES FOR INDUSTRIAL APPLICATIONsa James I. Mills D. S. Plaster EG&G Idaho, Inc. Idaho National Engineering Laboratory Idaho Falls, 10 83415 ABSTRACT The Department of Energy (DOE), Office of Industrial Programs (OIP...

  18. Skin thickness effects on in vivo LXRF

    SciTech Connect (OSTI)

    Preiss, I.L.; Washington, W. II

    1995-12-31

    The analysis of lead concentration in bone utilizing LXRF can be adversely effected by overlying issue. A quantitative measure of the attenuation of the 10.5 keV Pb L a x-ray signal by skin and skin equivalent plastic has been conducted. Concentration ranges in plaster of Paris and goat bone from 7 to 90 ppm with attenuators of Lucite{reg_sign} and pig skin were examined. It is concluded that no quantitative or semi quantitative analysis can be achieved if overlying sue thickness exceeds 3 mm for Ph concentrations of less than 30 porn Ph in bone.

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

    SciTech Connect (OSTI)

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

    2013-03-04

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

  20. Domain Bridging Interactions in the Allosteric Network for IIAGlc Inhibition of the Escherichia coli Glycerol Kinase 

    E-Print Network [OSTI]

    Acquaye, Edith Abena

    2011-10-21

    2. Q37A PRIMER 1: 5? - CAG CGC GAA TTT GAG CAA ATC TAC CCA AAA CCA - 3? PRIMER 2: 5? - TGG TTT TGG GTA GAT TTG CTC AAA TTC GCG CTG - 3? Y39A PRIMER 1: 5?- GAA TTT GAG CAA ATC TAC CCA AAA CCA GGT TGG - 3? PRIMER 2: 5?- CCA ACC TGG TTT... TGG GTA GAT TTG CTC AAA TTC - 3? Y39F PRIMER 1: 5? - GAA TTT GAG CAA ATC TTT CCA AAA CCA GGT TGG - 3? PRIMER 2: 5?- CCA ACC TGG TTT TGG AAA GAT TTG CTC AAA TTC - 3? 12 Q104A PRIMER 1: 5? - AAC GCC ATT GTC TGG CAG TGC CGT CGT ACC...

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

    SciTech Connect (OSTI)

    Sadia, Cyril P.; Laganapan, Aleena Maria; Agatha Tumanguil, Mae; Estacio, Elmer; Somintac, Armando; Salvador, Arnel; Que, Christopher T.; Yamamoto, Kohji; Tani, Masahiko

    2012-12-15

    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.

  2. Strain relaxation of GaAs/Ge crystals on patterned Si substrates

    SciTech Connect (OSTI)

    Taboada, A. G., E-mail: gonzalez@phys.ethz.ch; Kreiliger, T.; Falub, C. V.; Känel, H. von [Laboratory for Solid State Physics, ETH Zürich, Otto-Stern-Weg 1, CH-8093 Zürich (Switzerland); Isa, F.; Isella, G. [L-NESS, Department of Physics, Politecnico di Milano, via Anzani 42, I-22100 Como (Italy); Salvalaglio, M.; Miglio, L. [L-NESS, Department of Materials Science, Università di Milano-Bicocca, via Cozzi 55, I-20125 Milano (Italy); Wewior, L.; Fuster, D.; Alén, B. [IMM, Instituto de Microelectrónica de Madrid (CNM, CSIC), C/Isaac Newton 8, E-28760 Tres Cantos, Madrid (Spain); Richter, M.; Uccelli, E. [Functional Materials Group, IBM Research-Zürich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Niedermann, P.; Neels, A.; Dommann, A. [Centre Suisse d'Electronique et Microtechnique, Jaquet-Droz 1, CH-2002 Neuchatel (Switzerland); Mancarella, F. [CNR-IMM of Bologna, Via Gobetti 101, I-40129 Bologna (Italy)

    2014-01-13

    We report on the mask-less integration of GaAs crystals several microns in size on patterned Si substrates by metal organic vapor phase epitaxy. The lattice parameter mismatch is bridged by first growing 2-?m-tall intermediate Ge mesas on 8-?m-tall Si pillars by low-energy plasma enhanced chemical vapor deposition. We investigate the morphological evolution of the GaAs crystals towards full pyramids exhibiting energetically stable (111) facets with decreasing Si pillar size. The release of the strain induced by the mismatch of thermal expansion coefficients in the GaAs crystals has been studied by X-ray diffraction and photoluminescence measurements. The strain release mechanism is discussed within the framework of linear elasticity theory by Finite Element Method simulations, based on realistic geometries extracted from scanning electron microscopy images.

  3. Solid-state lighting :lamp targets and implications for the semiconductor chip.

    SciTech Connect (OSTI)

    Tsao, Jeffrey Yeenien

    2003-01-01

    Once again GaAs MANTECH (with III-Vs Review acting as media sponsor) promises to deliver high quality papers covering all aspects of compound semiconductor manufacturing, with speakers from leading-edge equipment, epiwafer, and device suppliers. Since its launch in 1986, GaAs MANTECH has consistently been one of the highlight events of the conference calendar. Coverage includes all compound-based semiconductors, not just GaAs. With an excellent technical program comprising of almost 80 papers and expanded workshop sessions, the 2003 event should prove the best ever. As in previous years, an Interactive Forum and Ugly Picture Contest will be included. A major attraction will be the associated exhibition, with more than 70 suppliers expected to participate.

  4. The molecular mechanisms involved in the genetic instability of the CCTG. CAGG repeats associated with myotonic dystrophy type 2 

    E-Print Network [OSTI]

    Dere, Ruhee J.

    2006-08-16

    , and transcription in generating the dynamic mutations observed with these microsatellite disorders (5-8). The ability of the repetitive DNA sequences, including CTG?CAG, CGG?CCG, GAC?GTC, GAA?TTC, CCTG?CAGG and ATTCT?AGAAT to adopt non-B DNA structures... transcripts (72-75). Friedreich?s ataxia caused by the expansion of a GAA?TTC repeat in intron 1 of the frataxin gene (76-78) is one of the triplet repeat disorders that does not exhibit anticipation, a characteristic of most of the other TRS diseases...

  5. Isoelectronic co-doping

    DOE Patents [OSTI]

    Mascarenhas, Angelo

    2004-11-09

    Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  6. Anisotropic reactive ion etching of vanadium dioxide 

    E-Print Network [OSTI]

    Radle, Byron K

    1990-01-01

    Facility for Submicron Structures, Cornell University, Ithaca, New York [7]. In these studies thin film VO2 was etched with a SF6/CO2 chemistry. SF6 chemistry was chosen because volatile vanadium fluorides can be formed easily. CO2 supplied the carbon... (Silicon Doped GaAs) Semi-Insulating GaAs Metal (AuGe, Ni, Au) Fig. 19. This is a step by step drawn representation of the fabrication procedure. 53 1. Pattern Photo Resist for Optical Stack etch mask. P Etched VOz in CFe plasma. 3. Etched Alz...

  7. Three-junction solar cells comprised of a thin-film GaInP/GaAs tandem cell mechanically stacked on a Si cell

    SciTech Connect (OSTI)

    Yazawa, Y.; Tamura, K.; Watahiki, S.; Kitatani, T.; Ohtsuka, H.; Warabisako, T.

    1997-12-31

    Three-junction tandem solar cells were fabricated by mechanical stacking of a thin-film GaInP/GaAs monolithic tandem cell and a Si cell. The epitaxial lift-off (ELO) technique was used for the thinning of GaInP/GaAs tandem cells. Both spectral responses of the GaInP top cell and the GaAs middle cell in the thin-film GaInP/GaAs monolithic tandem cell were conserved. The Si cell performance has been improved by reducing the absorption loss in the GaAs substrate.

  8. Solid-state photonic interfaces using semiconductor quantum dots

    E-Print Network [OSTI]

    Boyer de la Giroday, Antoine

    2012-02-07

    . Rev. Lett. 106, 216802 (2011) 5. Coherent entangled light generated by quantum dots in the presence of nuclear magnetic fields R.M. Stevenson, C.L. Salter, A. Boyer de la Giroday, I. Farrer, C.A. Nicoll, D.A. Ritchie, and A.J. Shields arXiv:1103.2969v1... Bragg reflectors (DBRs) surround- ing the cavity region made of a GaAs spacer layer containing the QDs. Each DBR consists of alternating layers of high- and low-refractive index materi- als (respectively GaAs with n = 3.54 and AlAs n = 2.97 in our case...

  9. Current-matched high-efficiency, multijunction monolithic solar cells

    DOE Patents [OSTI]

    Olson, Jerry M. (Lakewood, CO); Kurtz, Sarah R. (Golden, CO)

    1993-01-01

    The efficiency of a two-junction (cascade) tandem photovoltaic device is improved by adjusting (decreasing) the top cell thickness to achieve current matching. An example of the invention was fabricated out of Ga.sub.0.52 In.sub.0.48 P and GaAs. Additional lattice-matched systems to which the invention pertains include Al.sub.x Ga.sub.1-x /GaAS (x= 0.3-0.4), GaAs/Ge and Ga.sub.y In.sub.l-y P/Ga.sub.y+0.5 In.sub.0.5-y As (0

  10. Strength of semiconductors, metals, and ceramics evaluated by a microscopic cleavage model with Morse-type and Lennard-Jones-type interaction

    SciTech Connect (OSTI)

    Hess, Peter

    2014-08-07

    An improved microscopic cleavage model, based on a Morse-type and Lennard-Jones-type interaction instead of the previously employed half-sine function, is used to determine the maximum cleavage strength for the brittle materials diamond, tungsten, molybdenum, silicon, GaAs, silica, and graphite. The results of both interaction potentials are in much better agreement with the theoretical strength values obtained by ab initio calculations for diamond, tungsten, molybdenum, and silicon than the previous model. Reasonable estimates of the intrinsic strength are presented for GaAs, silica, and graphite, where first principles values are not available.

  11. Origin and paleogeography of an immense, nonmarine Miocene salt deposit in the Basin and Ranges (Western USA)

    E-Print Network [OSTI]

    Faulds, James E.; Schreiber, Charlotte; Reynolds, Stephen; Gonzá lez, Luis; Okaya, David

    1997-01-01

    economic resources within continental rifts. They furnish strategic minerals (halite, gypsum, bo­ rates), storage capacity for natural gas and nuclear wastes (e.g., Johnson and Gonzales 1978; Dean and Johnson 1989), and effective seals for hydrocarbons... exceeding 1280 m in thickness (Table 1). Reports of abundant saline ground-water prompted the first deep dril­ ling in the basin in 1958 (H.W. Peirce written comm. 1993). The salt has since been studied as a potential repository for nuclear wastes...

  12. Worksheet Page 1 Name __________________________________________ Date____________________

    E-Print Network [OSTI]

    Lance, Veronica P.

    Mile town or city HRM 124 Stuyvesant HRM 115 Athens HRM 97 Ulster HRM 87 Esopus HRM 61 Beacon HRM 18 Yonkers HRM 7 Manhattan ship Gypsum Baron 9:45 AM south 10:45 AM anchored ship Alice Oldendorff 1:02 PM) At that speed, how long would the Oldendorff take to travel between HRM 115 and HRM 7? (e) At what time would

  13. Coal combustion products 2007 production and use report

    SciTech Connect (OSTI)

    2009-07-01

    The American Coal Ash Association's 2007 Annual Coal Combustion Products (CCP) are derived from data from more than 170 power plants. The amount of CCPs used was 40.55%, a decrease of 2.88% from 2006, attributed to reduced fuel burn and a decrease in demand in the building industry. Figures are given for the production of fly ash, flue gas desulfurization gypsum, bottom ash, FBC ash and boiler slag. The article summarises results of the survey. 1 ref., 1 tab.

  14. Experimental and Analytical Research on Fracture Processes in ROck

    SciTech Connect (OSTI)

    Herbert H.. Einstein; Jay Miller; Bruno Silva

    2009-02-27

    Experimental studies on fracture propagation and coalescence were conducted which together with previous tests by this group on gypsum and marble, provide information on fracturing. Specifically, different fracture geometries wsere tested, which together with the different material properties will provide the basis for analytical/numerical modeling. INitial steps on the models were made as were initial investigations on the effect of pressurized water on fracture coalescence.

  15. Recovery Act : Near-Single-Crystalline Photovoltaic Thin Films on Polycrystalline, Flexible Substrates

    SciTech Connect (OSTI)

    Venkat Selvamanickam; Alex Freundlich

    2010-11-29

    III-V photovoltaics have exhibited efficiencies above 40%, but have found only a limited use because of the high cost of single crystal substrates. At the other end of the spectrum, polycrystalline and amorphous thin film solar cells offer the advantage of low-cost fabrication, but have not yielded high efficiencies. Our program is based on single-crystalline-like thin film photovoltaics on polycrystalline substrates using biaxially-textured templates made by Ion Beam-Assisted Deposition (IBAD). MgO templates made by IBAD on flexible metal substrate have been successfully used for epitaxial growth of germanium films. In spite of a 4.5% lattice mismatch, heteroepitaxial growth of Ge was achieved on CeO2 that was grown on IBAD MgO template. Room temperature optical bandgap of the Ge films was identified at 0.67 eV indicating minimal residual strain. Refraction index and extinction coefficient values of the Ge films were found to match well with that measured from a reference Ge single crystal. GaAs has been successfully grown epitaxially on Ge on metal substrate by molecular beam epitaxy. RHEED patterns indicate self annihilation of antiphase boundaries and the growth of a single domain GaAs. The GaAs is found to exhibit strong photoluminescence signal and, an existence of a relatively narrow (FWHM~20 meV) band-edge excitons measured in this film indicates a good optoelectronic quality of deposited GaAs. While excellent epitaxial growth has been achieved in GaAs on flexible metal substrates, the defect density of the films as measured by High Resolution X-ray Diffraction and etch pit experiments showed a high value of 5 * 10^8 per cm^2. Cross sectional transmission electron microscopy of the multilayer architecture showed concentration of threading dislocations near the germanium-ceria interface. The defect density was found decrease as the Ge films were made thicker. The defects appear to originate from the MgO layer presumably because of large lattice mismatches between the various layers. The defect density in GaAs was reduced by a factor of five by adding a step of in-situ deposition of Ge by MBE on the sputtered Ge prior to GaAs growth. We have investigated device design strategies that would support development of high-efficiency devices in presence of dislocation densities of 10^8 cm^-2 present in our epitaxial GaAs films. Results from modeling work show that with a proper emitter, base and doping selection, the modeled efficiency of a GaAs cells with dislocation densities of 10^9 and 10^8 cm^-2 could be increased from 1% and 7% to 11% and 17% respectively. Under AM0, this single junction GaAs solar cell, has optimized value of emitter and base thickness of around 0.7 and 1.7 microns respectively, to give a maximum efficiency of 24.2%. We have fabricated complete GaAs solar cells using our Ge films on metal substrates. Pattern resolution of few microns with well-defined grid line of 30 microns has been realized on few cm square flexible templates. The ability to grow single-crystalline-like Ge films on flexible, polycrystalline substrates by reel-to-reel tape processing now provides an immense potential to fabricate high quality III-V photovoltaics on flexible, inexpensive substrates.

  16. Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur. Fifth quarterly technical progress report, December 1996

    SciTech Connect (OSTI)

    NONE

    1996-12-01

    More than 170 wet scrubber systems applied, to 72,000 MW of U.S., coal-fired, utility boilers are in operation or under construction. In these systems, the sulfur dioxide removed from the boiler flue gas is permanently bound to a sorbent material, such as lime or limestone. The sulfated sorbent must be disposed of as a waste product or, in some cases, sold as a byproduct (e.g. gypsum). Due to the abundance and low cost of naturally occurring gypsum, and the costs associated with producing an industrial quality product, less than 7% of these scrubbers are configured to produce usable gypsum (and only 1% of all units actually sell the byproduct). The disposal of solid waste from each of these scrubbers requires a landfill area of approximately 200 to 400 acres. In the U.S., a total of 19 million tons of disposable FGD byproduct are produced, transported and disposed of in landfills annually. The use of regenerable sorbent technologies has the potential to reduce or eliminate solid waste production, transportation and disposal. In a regenerable sorbent system, the sulfur dioxide in the boiler flue gas is removed by the sorbent in an adsorber. The S0{sub 2}s subsequently released, in higher concentration, in a regenerator. All regenerable systems produce an off-gas stream from the regenerator that must be processed further in order to obtain a salable byproduct, such as elemental sulfur, sulfuric acid or liquid S0{sub 2}.

  17. Eighth Annual Student Research

    E-Print Network [OSTI]

    Southern California, University of

    fracture networks in uncoventional reservoirs using microseismic data (with Fred Aminzadeh) 12:05 PM lunch Dongseok Kang Carbon-doped GaAs single junction solar cells grown in multilayer epitaxial assemblies (with, Aiichiro Nakano, and Priya Vashishta) 11:50 PM Tayeb A. Tafti Integrated workflow for characterizing

  18. Deep-level transient spectroscopy of InAs/GaAs quantum dot superlattices

    SciTech Connect (OSTI)

    Sobolev, M. M.; Nevedomskii, V. N.; Zolotareva, R. V.; Vasil'ev, A. P.; Ustinov, V. M.

    2014-02-21

    Deep level transient spectroscopy (DLTS) has been applied to study the carrier emission from states of a 10-layer system of tunnel-coupled vertically correlated quantum dots (VCQDs) in p-n InAs/GaAs heterostructures with different widths of GaAs spacers under varied reverse bias (U{sub r}) and filling voltage pulse U{sub f}.

  19. Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum A. Nauen,* F. Hohls, J. Konemann, and R. J. Haug

    E-Print Network [OSTI]

    Hohls, Frank

    Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum A; published 30 March 2004 We investigate the noise properties of a GaAs /AlxGa1 xAs resonant discuss the suppression of the shot noise in the framework of a coupled two-state system. For large bias

  20. LEDs_3LEDs_3 current efficiency

    E-Print Network [OSTI]

    Pulfrey, David L.

    1 LEDs_3LEDs_3 LECTURE 12 · current efficiency · extraction efficiency · wall-plug efficiency efficiencySec. 8.4 How much power gets out for GaAs? Adapted from Schubert, loc. cit. #12;5 Design to improve extraction efficiencyDesign to improve extraction efficiencySec. 8.4 What are the features of this LED from

  1. GUARANTEED ADMISSION AGREEMENT Northern Virginia Community College (NOVA)

    E-Print Network [OSTI]

    Hammack, Richard

    1 GUARANTEED ADMISSION AGREEMENT Between Northern Virginia Community College (NOVA) And Virginia admission agreement (GAA) establishes a collaborative arrangement between NOVA and VCU for the benefit in Liberal Studies for Early and Elementary Education (LSEE) and Master of Teaching degree in Elementary

  2. Regulation of Colonocyte Apoptosis by Bcl-2: Influence of Chemotherapeutic Dietary Agents 

    E-Print Network [OSTI]

    Turk, Harmony

    2011-08-04

    GAT GTA CCG TCT GTA CAT GCT GAA GAT AAT Amino acid sequence: ITTVESNSSWWTTGLSLRLCSGLSPDVPSVHAEDN Mitochondrial-targeted Nucleotide sequence: CTG ATT CTC GCC ATG CTG GCA ATT GGG GTG TTC TCC CTC GGC GCC TTC ATT AGA TCA TTC AGC TCC GGA AGA...

  3. JOURNAL DE PHYSIQUE IV Colloque C6 Supplement au Journal de Physique Ill, Volume 4, juin 1994 C6-147

    E-Print Network [OSTI]

    Fossum, Eric R.

    -out applications. However, silicon is not well suited to deep cryogenic operation. Moderately doped silicon freezes-147 GaAs JFETs intended for deep cryogenic VLWIR readout electronics TJ. Cunningham and E.R. Fossum Mail-effect transistors (JFETs) are promising for deep cryogenic «10K) readout electronics applications. This paper

  4. Nuclear Instruments and Methods in Physics Research A 343 (1994) 527-538 North-Holland

    E-Print Network [OSTI]

    Terry, Fred L.

    1994-01-01

    Nuclear Instruments and Methods in Physics Research A 343 (1994) 527-538 North-Holland Present status of undoped semi-insulating LEC bulk GaAs as a radiation spectrometer NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SectionA Douglas S. McGregor a,*, Ronald A. Rojeski a, Glenn F. Knoll a, Fred L. Terry

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

    E-Print Network [OSTI]

    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.

    2006-01-01

    the semiphenomenological virtual crystal model the valence band holes experience a mean-field hMF =JpdNMn?S , and the band Hamiltonian can then be written as H? MF=H? KL?B?+hMFs?z, where H? KL?B? is the B-dependent six- band Kohn-Luttinger Hamiltonian of the GaAs host...

  6. Modeling multifrequency eddy current sensor interactions during vertical Bridgman growth of semiconductors

    E-Print Network [OSTI]

    Wadley, Haydn

    Modeling multifrequency eddy current sensor interactions during vertical Bridgman growth methods have been used to analyze the responses of two ``absolute'' and ``differential'' eddy current conductivity ratio increases. Of the materials studied, GaAs is found best suited for eddy current sensing

  7. Controlling Mn depth profiles in GaMnAs during high-temperature molecular beam epitaxial growth

    E-Print Network [OSTI]

    Thibado, Paul M.

    , or spintronics [1]. The reason for this is that, compared to conventional electronic devices, spin-based devices be suitable for spintronics. For example, the discovery of ferromagnetism in Mn-doped GaAs grown by MBE [4] has led to interest in it as an ideal material for spintronics applications [5,6]. The future success

  8. Dynamics of impurity and valence bands in Ga1-xMnxAs within the dynamical mean-field approximation

    E-Print Network [OSTI]

    Jarrell, Mark

    candidates for spintronic applications.1 In particular, GaAs doped with Mn Ga1-xMnxAs is promising as a spin-carrier injector in spintronic devices2 due to its relatively high mag- netic transition temperature3 and its

  9. The LEGISLATIVE FINANCE COMMITTEE University of New Mexico

    E-Print Network [OSTI]

    New Mexico, University of

    Report to The LEGISLATIVE FINANCE COMMITTEE University of New Mexico Program Evaluation: State Recognition................................................ 58 #12;University of New Mexico, Report #11 millions) FY08 $84.6 FY09 $93.1 FY10 $97.8 FY11 $93.7 Source: GAA The University of New Mexico (UNM) Health

  10. 50TH ANNIVERSARY Quantitative correlation of interfacial contamination

    E-Print Network [OSTI]

    Florida, University of

    50TH ANNIVERSARY Quantitative correlation of interfacial contamination and antiphase domain Science+Business Media New York 2015 Abstract The role of interfacial contamination on anti- phase domain surface contamination across the wafer. APB density in the as-grown GaAs film was examined with the aid

  11. NATIONAL RADIO ASTRONOMY OBSERVATORY GREEN BANK/ WEST VIRGINIA

    E-Print Network [OSTI]

    Groppi, Christopher

    -End Instrumentation Chassis .......... . 4 1. Constant Current Power Supplies for GaAs FET's 4 2. Solid State Relay · · · · ·· · .. ·· ···· ·· · 6 LAB TEST DATA Gain Measurements ........ . ...... -- ····· · ··· 4.· · .0 0... · 7 Noise Tem erature Measurements ..... Impedance Measurements TELESCOPE TEST DATA Gain Measurements Noise Tem erature

  12. Acousto-optical coherence tomography using random phase jumps on

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    (cm). Up to now, several configurations have been studied, giving a millimetric axial resolution demonstration is performed with a self-adaptive holographic setup containing a photorefractive GaAs bulk crystal(5), 1151­1158 (1997). 4. S. Leveque, A. C. Boccara, M. Lebec, and H. Saint-Jalmes, "Ultrasonic tagging

  13. 1204 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 34, NO. 9, SEPTEMBER 1999 Breakdown in Millimeter-Wave Power InP

    E-Print Network [OSTI]

    del Alamo, Jesús A.

    's) deliver lower output power than GaAs pseudomorphic HEMT's (PHEMT's) throughout most of the millimeter-wave for millimeter-wave power amplification is still a matter of debate. At this time, a review of the literature of merit with which millimeter-wave system designers are concerned. Power-added efficiency (PAE

  14. May 20, 2010 Growing gallium arsenide in thick multilayer stacks could make a big

    E-Print Network [OSTI]

    Rogers, John A.

    of substrates, including glass and plastic. In photovoltaics, we expect the cost reductions to be significant, and that the ability to put cells on thin sheets of flexible plastic will increase the mechanical robustness://images.iop.org/objects/opo/news/16/5/11/gaas2.jpg) This strategy does not consume the wafer, which can be reused for many rounds

  15. Impact of ?110? uniaxial strain on n-channel In0.15Ga0.85As high electron mobility transistors

    E-Print Network [OSTI]

    del Alamo, Jesus A.

    This letter reports on a study of the impact of ?110? uniaxial strain on the characteristics of InGaAs high electron mobility transistors (HEMT) by bending GaAs chips up to a strain level of 0.4%. Systematic changes in ...

  16. Delta II rocket launching the Mars Exploration Rover,

    E-Print Network [OSTI]

    Torgersen, Christian

    diodes (LEDs), laser diodes, photo detectors, and solar cells. These devices are important of efficient solar cells. Gallium is also used in some unusual applications. Thermal convection in liquidN (gallium nitride), and CIGS (copper-indium-gallium selenide) direct band-gap semiconductors. GaAs and Ga

  17. Thermodynamics, Entropy, Information and the Efficiency of Solar Cells

    E-Print Network [OSTI]

    Abrams, Zeev R.

    2012-01-01

    CIGS, so the addition of the dc layer would not alter the material choice for a solar cell.solar cell, the use of GaAs has recently become feasible due to scalable manufacturing techniques, and compound materials such as CIGS (

  18. Dimensional crossover and weak localization in a 90 nm n-GaAs thin film A. M. Gilbertson,1

    E-Print Network [OSTI]

    Bashir, Rashid

    for Materials Innovation, Washington University in St. Louis, 1 Brookings Drive, St. Louis, Missouri 63130, USA diffusive transport at the nanoscale.1 Alternatively, ma- terials with lower , such as GaAs, offer in terms of cost and processing complexity and are also appli- cable to the EEC effect. Accordingly, we

  19. Connections What is a Modular Category?

    E-Print Network [OSTI]

    Rowell, Eric C.

    Fractional Quantum Hall Effect 1011 electrons/cm2 10 Tesla defects=quasi-particles 9 mK GaAs Eric Rowell has generators i , i = 1, . . . , n - 1 satisfying: i i+1i = i+1i i+1 i j = j i if |i - j| > 1 Eric

  20. ELECTROSTATIC (LANGMUIR) PROBE MEASUREMENTS IN RF DRIVEN He, N2, BCl3, AND BCl3/N2 PLASMAS

    E-Print Network [OSTI]

    Pathak, Bogdan Amaru

    2008-08-01

    of GaAs with nitrogen addition. The system was validated in both helium and nitrogen plasmas. Probe measurements showed that as the nitrogen concentration in BCl3/N2 plasmas increased, the average electron energy actually decreased (5.52 eV @ 0% N2, 4...

  1. Single-chip fused hybrids for acousto-electric and acousto-optic applications

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    Single-chip fused hybrids for acousto-electric and acousto-optic applications M. Rotter,a) C. Rocke and optical properties of a semiconductor hetero-junction and the acoustic properties of a piezoelectric-optic applications. LiNbO3 /GaAs hybrids have been fabricated using the epitaxial lift-off technique resulting

  2. Lasing characteristics of GaSb/GaAs self-assembled quantum dots embedded in an InGaAs quantum well

    E-Print Network [OSTI]

    Jalali. Bahram

    Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico, New Mexico 87545 Received 26 February 2007; accepted 1 June 2007; published online 28 June 2007 intriguing optoelectronic device possibilities on GaAs substrates including lasers, detectors, or solar cells

  3. Fundamentals of Laser Safety

    E-Print Network [OSTI]

    Sin, Peter

    or Helium/Neon, or semiconductors such as GaAs. Active mediums contain atoms whose electrons may be excited. If the energy from this photon is of the precise wavelength, it will stimulate the production of another photon-UV) Helium cadmium (UV) Nitrogen (UV) Helium cadmium (violet) Krypton (blue) Argon (blue) Copper vapor (green

  4. EE Times: Semi News Groups claim breakthroughs in solar cells

    E-Print Network [OSTI]

    Rogers, John A.

    -based, multi-junction solar cells. Module cost is minimized by using high concentration ratio. XEE Times: Semi News Groups claim breakthroughs in solar cells Mark LaPedus Page 1 of 2 EE Times (05 separately claimed breakthroughs in solar cell production. Gallium arsenide (GaAs) and related compounds

  5. The effect of substrates on the Raman spectrum of graphene: Graphene-on-sapphire and graphene-on-glass

    E-Print Network [OSTI]

    The effect of substrates on the Raman spectrum of graphene: Graphene- on-sapphire and graphene The authors investigated the influence of substrates on Raman scattering spectrum from graphene. The room-temperature Raman signatures from graphene layers on GaAs, sapphire, and glass substrates were compared with those

  6. Qhh/czku"gngevtqp"jqnqitcrj{"qh"hqewugf"kqp"dgco"oknngf"IcCu" cpf"Uk"r/p"lwpevkqpu"

    E-Print Network [OSTI]

    Dunin-Borkowski, Rafal E.

    on a 4 × 1018 cm-3 Sb-doped (n-type) substrate. GaAs p-n and n-p junctions were also grown using MBE, Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, U.K. CDUVTCEVjunctions have been potentials measured across the junctions. 30""KPVTQFWEVKQP Off-axis electron holography is a powerful

  7. Performance Enhancement of a Graphene-Zinc Phosphide Solar Cell using the Electric Field-Effect

    E-Print Network [OSTI]

    Zettl, Alex

    in step 1 (from step 2 to 8 we only show the Zn3P2 and we omit the GaAs substrate). Then an oxide layer). The oxide-1 layer prevents an electric short between the Au-C and Zn3P2. Then the gate oxide layer, labelled

  8. Ultra-low power fiber-coupled gallium arsenide photonic crystal cavity electro-optic modulator

    E-Print Network [OSTI]

    Vuckovic, Jelena

    -induced change in refractive index of InP, GaAs, and InGaAsP," IEEE J. Quantum Electron. 26(1), 113­122 (1990). 7, "Ultra-low threshold, electrically pumped quantum dot photonic crystal nanocavity laser," to be published

  9. Version 5; 7 October 1999 Quantum dots induced by strain from buried and surface stressors

    E-Print Network [OSTI]

    Davies, John H.

    induced by strain from buried, self-assembled dot InP stressor InGaAs quantum well GaAs substrate GaVersion 5; 7 October 1999 Quantum dots induced by strain from buried and surface stressors John H 93106­4170 (Dated: 8 November 1999) Abstract Quantum dots can be induced in a quantum well by strain

  10. 506 NATURE PHOTONICS | VOL 4 | AUGUST 2010 | www.nature.com/naturephotonics news & views

    E-Print Network [OSTI]

    Jalali. Bahram

    such as organic polymer semiconductors or colloidal quantum dots, both of which can be deposited onto plastic be made from conventional inorganic semiconductors such as GaAs and InP, thanks to a new innovative to reduce the mechanical strain on the LED quantum wells when the substrate is folded or flexed

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

    E-Print Network [OSTI]

    be well suited for exploitation of long wavelength quantum dot and dilute nitride technology, resulting in single lateral mode emission from an In0.17Ga0.83As double quantum well laser. Introduction: Lasers based on the GaAs materials system offer advan- tages over their InP counterparts, such as the use

  12. 2006 by Ania Bleszynski All rights reserved.

    E-Print Network [OSTI]

    to make an InAs quantum dot defined by two InP barriers. I demonstrate the ability of the cooled SPM tip to image a one-electron GaAs quantum dot formed in a 2DEG by surface gates. Few electron quantum dots and manipulating electrons in quantum dots promises to be useful in understanding and building circuits

  13. Optical Characterization of Ultrasmall Si Nanoparticles Prepared through Electrochemical Dispersion of Bulk Si

    E-Print Network [OSTI]

    Braun, Paul

    dots (CQDs) such as ZnS, CdSe, GaAs, and InP nanoparticles.26-35 Progress with the core-shell synthesis for biological systems. Most of the investigations in this area have focused on the direct gap, compound quantum

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

    E-Print Network [OSTI]

    Kangude, Yamini

    2005-01-01

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

  15. J. Phys.: Condens. Matter 8 (1996) 41894193. Printed in the UK Angle-resolved photoemission of InSb(111)2 2

    E-Print Network [OSTI]

    Kim, Sehun

    1996-01-01

    Abstract. The electronic band structure of InSb(111) along the ­ ­L 111 direction was determined using structures of GaAs(111)­2 × 2 surfaces was also carried out to determine the atomic geometry [7, 8]. However to the surface state and the resonance process of the InSb(111)­2 × 2. Investigations of electronic properties

  16. NanofabricationTechnologies for Optoelectronics, Imaging, Sensing, and Displays

    E-Print Network [OSTI]

    Eustice, Ryan

    , the group is working on exceptionally low-cost, ultra-thin film InP and GaAs solar cells cold welded in organic solar cells, nanolasers, flexible displays, optical metamaterial structures, photo- acoustic pioneering work in the development of high-performance InAs/GaAs lasers emitting at 1.0, 1.3, and 1.55µm

  17. Configuration Optimization of a Nanosphere Array on Top of a Thin Film Solar Cell

    E-Print Network [OSTI]

    Grandidier, Jonathan

    Configuration Optimization of a Nanosphere Array on Top of a Thin Film Solar Cell J. Grandidier photocurrent of the solar cell. On a typical thin film amorphous silicon solar cell, a parametric analysis of SiO2 spheres directly placed on top of a-Si [1] and gallium arsenide (GaAs) [3] solar cells. We

  18. Light-induced charge separation in thin tetraphenyl-porphyrin layers deposited on Au Y. Zidon and Yoram Shapira*

    E-Print Network [OSTI]

    Shapira, Yoram

    for applications in opto- electronics, such as organic light-emitting diodes or organic solar cells. Interfaces-phenylene vinylene coated Au or GaAs surfaces.11 However, none of the past SPS studies recognized internal processes, taking place in thin organic films deposited on Au. In t

  19. Eumelanin Dye-sensitized Solar Cell Grown with Matrix-assisted Pulsed Laser

    E-Print Network [OSTI]

    ] 3.2 × 10 25 1.2 -V GaAs #12; 2 1.3 Dye-sensitized solar cell,DSSC 1991Grätzel Eumelanin Dye-sensitized Solar Cell Grown with Matrix-assisted Pulsed Laser Evaporation~4 DHICA DHICA #12; III Abstract At present the majority dye-sensitized solar cell research all

  20. IEEE Spectrum: Thin-Film Trick Makes Gallium Arsenide Devices Cheap http://spectrum.ieee.org/semiconductors/materials/thinfilm-trick-makes-gallium-arsenide-devices-cheap[5/22/2010 1:39:13 PM

    E-Print Network [OSTI]

    Rogers, John A.

    to man," says Rogers, a materials engineer. Some GaAs solar cells can convert about 40 percent of the sun // MATERIALS NEWS Thin-Film Trick Makes Gallium Arsenide Devices Cheap Rubber-stamping makes creating solarIEEE Spectrum: Thin-Film Trick Makes Gallium Arsenide Devices Cheap http://spectrum.ieee.org

  1. Continuous nanoparticle generation and assembly by atmospheric pressure arc discharge

    E-Print Network [OSTI]

    Jacobs, Heiko O.

    to the manufacture of low cost printable electronics, optoelectronics, and solar cells with higher per- formance than eliminate this requirement providing a larger selection of materials including Si, Ge, GaN, and GaAs, and deposition of thin films and nanomaterials.3 Typically, a dis- tinction is made between low and atmospheric

  2. RESEARCH NEWS FEBRUARY 2007 | VOLUME 2 | NUMBER 1 9

    E-Print Network [OSTI]

    Rogers, John A.

    to epitaxial methods. In the process, nanoscale semiconductor components such as GaN, GaAs, or Si nanowires- area solar cells. D. Jason Palmer A three-layer stack of GaN high-electron mobility transistors, Si metal oxide semiconductor field-effect transistors, and SWNT thin-film transistors on a flexible

  3. Optical and Excitonic Properties of Crystalline ZnS Nanowires: Toward Efficient Ultraviolet

    E-Print Network [OSTI]

    Xiong, Qihua

    semiconductor, has been most widely used for phosphor host,5 optical coating, and solar cells.6 Due to the wide luminescence. Despite their advantageous band gap, bulk or thin film ZnS materials have not been able, such as ZnS epilayers fabricated on GaAs by MBE8 and NWs grown by PLV15 or MBE.20 Although those reports

  4. ECE Seminar in Nanophotonics Seeing the very small

    E-Print Network [OSTI]

    Pal, Ranadip

    and fabrication of thin-film solar cells that exploit plasmonic effects and light scattering by metal realization of extremely thin, highly efficient solar cells and related devices. Edward Yu received his A nanoparticles embedded epitaxially in GaAs enables elucidation of nanoscale electronic structure, carrier

  5. IOP PUBLISHING JOURNAL OF PHYSICS D: APPLIED PHYSICS J. Phys. D: Appl. Phys. 42 (2009) 145113 (9pp) doi:10.1088/0022-3727/42/14/145113

    E-Print Network [OSTI]

    Melnik, Roderick

    2009-01-01

    including light emitters [6­8], elements of solar cells [9], transparent conductive layers or buffer thin in electronics and optoelectronics. III­V semiconductor nano- structures, in particular GaN- and GaAs films [10] and CdTe, CdSe and CdS nanowires (NWs) based infra-red detection [11, 12]. Advances in growth

  6. Growth and characterization of single crystal rocksalt LaAs using LuAs barrier layers

    E-Print Network [OSTI]

    Texas at Austin, University of

    ) Light-management in ultra-thin polythiophene films using plasmonic monopole nanoantennas Appl. Phys of other LaAs phases, interfacial reactions between GaAs and LaAs, and polycrystalline LaAs growth. Examples include high- performance tunnel junctions for multijunction solar cells,4 epitaxial transparent

  7. Emerging High-Efficiency Low-Cost Solar Cell Technologies

    E-Print Network [OSTI]

    McGehee, Michael

    J. of Photovoltaics, 2 (2012) p. 303. Si GaAs #12;Why thin film GaAs;Gallium Arsenide · The 1.4 eV band gap is ideal for solar cells. · High quality films are grownEmerging High-Efficiency Low-Cost Solar Cell Technologies Mike McGehee Materials Science

  8. 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim (1 of 6) 1400919wileyonlinelibrary.com Device Architectures for Enhanced Photon Recycling in

    E-Print Network [OSTI]

    Li, Xiuling

    .com Device Architectures for Enhanced Photon Recycling in Thin-Film Multijunction Solar Cells Xing Sheng in the MJ structure. Experiments demonstrate that thin-film GaAs devices printed on low-index substrates), Multijunction (MJ) solar cells have the potential to operate across the entire solar spectrum, for ultrahigh

  9. ISSN 1616-301X Vol. 15, No. 1

    E-Print Network [OSTI]

    Rogers, John A.

    optical properties make them good candidates to serve as inorganic dopants for polymer-based solar cells-cost plastics and even paper, to generate a thin film of active components for building devices with perfor to synthesize nanowires or microfibers of these materials (e.g., GaAs and InP) in both gaseous and liquid media

  10. Introducing Perovskite Solar Cells to Undergraduates In this Viewpoint, we show that it is sufficiently easy and

    E-Print Network [OSTI]

    solar cells based on GaAs (gallium arsenide) single crystals are 29 and over 40% efficient in single 2 decades, solar cells based on thin-film polycrystalline materials, especially CdTe (cadmium. The experiment is suitable for chemistry students to learn about thin-film polycrystalline solar cells, energy

  11. ENI Renewable and Non-conventional Energy Prize 2012 High-efficiency solar cells based on nanophotonic design

    E-Print Network [OSTI]

    Polman, Albert

    demonstrated ultra-thin silicon solar cells on glass, world-record efficiency thin-film GaAs solar cells to solar cell design are applicable to other solar cell technologies as well, including thin-film CuInSe2ENI Renewable and Non-conventional Energy Prize 2012 High-efficiency solar cells based

  12. Full Spectrum Boost in Nanoparticle Solar Cells UC Davis/Theory: F.Gygi, M.Voros, GTZ

    E-Print Network [OSTI]

    designs are needed GaAs 29% Alta Devices HIT c-Si cell 26% Panasonic, SunPower Thin film CdTe 20Full Spectrum Boost in Nanoparticle Solar Cells UC Davis/Theory: F.Gygi, M.Voros, GTZ UC Davis% First Solar Organic solar cells 12% Sumitomo #12;Solar Energy Conversion: Basics 5 1. No absorption

  13. www.advenergymat.de Vol. 5 No. 1 January 7 2015

    E-Print Network [OSTI]

    Rogers, John A.

    sub-cells in the MJ structure. Experiments demonstrate that thin-film GaAs devices printed on low Recycling in Thin-Film Multijunction Solar Cells Xing Sheng, Myoung Hee Yun, Chen Zhang, Ala'a M. Al of the entire solar spectrum.[1] Multijuction (MJ) cells, by contrast, spectrally split sunlight into sub-cells

  14. Analytical determination of critical crack size in solar cells

    SciTech Connect (OSTI)

    Chen, C.P.

    1988-05-01

    Although solar cells usually have chips and cracks, no material specifications concerning the allowable crack size on solar cells are available for quality assurance and engineering design usage. Any material specifications that the cell manufacturers use were developed for cosmetic reasons that have no technical basis. Therefore, the Applied Solar Energy Corporation (ASEC) has sponsored a continuing program for the fracture mechanics evaluation of GaAs. Fracture mechanics concepts were utilized to develop an analytical model that can predict the critical crack size of solar cells. This model indicates that the edge cracks of a solar cell are more critical than its surface cracks. In addition, the model suggests that the material specifications on the allowable crack size used for Si solar cells should not be applied to GaAs solar cells. The analytical model was applied to Si and GaAs solar cells, but it would also be applicable to the semiconductor wafers of other materials, such as a GaAs thin film on a Ge substrate, using appropriate input data.

  15. Vertical Pillar-Superlattice Array and Graphene Hybrid Light Emitting Diodes

    E-Print Network [OSTI]

    Rogers, John A.

    after deposition of the thin metal films. Thermal annealing of the graphene/ metal (Gr/M) contact to the GaAs decreases the contact resistance, to provide enhanced carrier injection. The resulting PSL in solar cells, due to the suppressed reflec- tion at the output/input surfaces, increased areas

  16. Nonimaging Optical Gain in Luminescent Concentration through Photonic Control of Emission Etendue

    E-Print Network [OSTI]

    Rogers, John A.

    and show that it delivers three times more luminescent power to an opposing GaAs photovoltaic cell when their concentration ratio because their emission is angularly isotropic. Here, we use a luminescent thin film bilayer: luminescence, solar concentration, nonimaging optics, microcavity, spontaneous emission, photovoltaics

  17. 20434 Phys. Chem. Chem. Phys., 2013, 15, 20434--20437 This journal is c the Owner Societies 2013 Cite this: Phys.Chem.Chem.Phys.,2013,

    E-Print Network [OSTI]

    Rogers, John A.

    into the visible range, with beneficial effects on the performance of solar cells, as demonstrated with thin-film particular potential in high efficiency III­V (GaAs, InGaP, etc.) solar cells, where detailed balance limits Cite this: Phys.Chem.Chem.Phys.,2013, 15, 20434 Enhanced ultraviolet responses in thin-film InGaP solar

  18. Profiling the Built-in Electrical Potential in III-V Multijunction Solar Cells: Preprint

    SciTech Connect (OSTI)

    Jiang, C.-S.; Friedman, D. J.; Moutinho, H. R.; Al-Jassim, M. M.

    2006-05-01

    We report on a direct measurement of the electrical potential on cross-sections of GaInP2/GaAs multiple-junction solar cells by using an ultrahigh-vacuum scanning Kelvin probe microscope (UHV-SKPM). The UHV-SKPM allows us to measure the potential without air molecules being adsorbed on the cross-sectional surface. Moreover, it uses a GaAs laser with photon energy of 1.4 eV for the atomic force microscope (AFM) operation. This eliminated the light-absorption-induced bottom-junction flattening and top-junction enhancement, which happened in our previous potential measurement using a 1.85-eV laser for the AFM operation. Three potentials were measured at the top, tunneling, and bottom junctions. Values of the potentials are smaller than the potentials in the bulk. This indicates that the Fermi level on the UHV-cleaved (110) surface was pinned, presumably due to defects upon cleaving. We also observed higher potentials at atomic steps than on the terraces for both GaInP2 epitaxial layer and GaAs substrate. Combining scanning tunneling microscopy (STM) and SKPM measurements, we found that the potential height at steps of the GaAs substrate depends on the step direction, which is probably a direct result of unbalanced cations and anions at the steps.

  19. Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire-array

    E-Print Network [OSTI]

    Zhou, Chongwu

    Optical, electrical, and solar energy-conversion properties of gallium arsenide nanowire, and will aid in the design and optimization of nanowire-based systems for solar energy-conversion applications, and the photoelectrochemical energy-conversion properties of GaAs nanowire arrays were evaluated in contact with one

  20. Abstract A miniaturized optical set-up based on a CD-ROM player optic was developed for LAPS (light ad-

    E-Print Network [OSTI]

    Moritz, Werner

    device. The lateral res- olution of LAPS measurements can be improved by using GaAs as the semiconductor material instead of Si. The diffusion length of the minority charge carriers was deter- mined to be smaller properties. A map of pH-values in an electrolyte near to an insula- tor surface can be obtained by the light

  1. Arsenic decapping and pre-atomic layer deposition trimethylaluminum passivation of Al2O3/InGaAs(100) interfaces

    E-Print Network [OSTI]

    Kummel, Andrew C.

    Arsenic decapping and pre-atomic layer deposition trimethylaluminum passivation of Al2O3/InGaAs(100 traps in atomic-layer-deposited Al2O3/GaAs (001) metal-oxide- semiconductor capacitors using atmospheric of atomic layer deposition temperature on HfO2/InGaAs metal-oxide-semiconductor interface properties J. Appl

  2. Quantum wells on indium gallium arsenic compositionally graded buffers realized by molecular beam epitaxy

    E-Print Network [OSTI]

    Choy, Henry Kwong Hin, 1974-

    2005-01-01

    For a long time, there has been a desire to extend the emission wavelength of GaAs-based quantum well lasers, with the aim of eventually replacing InP with GaAs as the substrate of choice for communication applications. ...

  3. Microscopic mechanism of the noncrystalline anisotropic magnetoresistance in (Ga,Mn)As 

    E-Print Network [OSTI]

    Vyborny, Karel; Kucera, Jan; Sinova, Jairo; Rushforth, A. W.; Gallagher, B. L.; Jungwirth, T.

    2009-01-01

    Starting with a microscopic model based on the Kohn-Luttinger Hamiltonian and kinetic p-d exchange combined with Boltzmann formula for conductivity we identify the scattering from magnetic Mn combined with the strong spin-orbit interaction of the GaAs...

  4. Cogenerating Photovoltaic and Thermal Solar Collector

    E-Print Network [OSTI]

    Su, Xiao

    Cogenerating Photovoltaic and Thermal Solar Collector Jinny Rhee and Jim Mokri COE Faculty peak load and irradiance hours of the day #12;Design · Parabolic solar collector · GaAs PV cells · Solar Energy and Alternative Energy can contribute to the energy supply ­ Renewable, doesn't emit

  5. The system for delivery of IR laser radiaton into high vacuum

    E-Print Network [OSTI]

    Abakumova, E V; Krasnov, A A; Muchnoi, N Yu; Pyata, E E

    2015-01-01

    The system for insertion of a laser beam into the vacuum chamber of high-energy storage ring is described. The main part of the system is the high-vacuum viewport for the IR radiation, based on ZnSe or GaAs crystals. The design of the viewports is presented.

  6. AFLEXIBLE APPROACH TO 5GHz U-NII BAND WLAN RADIO DEVELOPMENT

    E-Print Network [OSTI]

    Chapelle¼, Paul Schwab¼, Bill Griffin¼, Finbarr McGrath¼, Graham Wells¼, Brian English¼, Neil Weste*, Tony Parker-end in GaAs and the integration of the IF, filters, ADCs and DACs in CMOS. As a result of our efforts we units). Accordingly, we have a dual approach to the problem. Using specially designed 5 GHz Ga

  7. Profiling the Built-In Electrical Potential in III-V Multijunction Solar Cells

    SciTech Connect (OSTI)

    Jiang, C.-S.; Friedman, D. J.; Moutinho, H. R.; Al-Jassim, M. M.

    2006-01-01

    We report on a direct measurement of the electrical potential on cross-sections of GaInP{sub 2}/GaAs multiple-junction solar cells by using an ultrahigh-vacuum scanning Kelvin probe microscope (UHV-SKPM). The UHV-SKPM allows us to measure the potential without air molecules being adsorbed on the cross-sectional surface. Moreover, it uses a GaAs laser with photon energy of 1.4 eV for the atomic force microscope (AFM) operation. This eliminated the light-absorption-induced bottom-junction flattening and top-junction enhancement, which happened in our previous potential measurement using a 1.85-eV laser for the AFM operation. Three potentials were measured at the top, tunneling, and bottom junctions. Values of the potentials are smaller than the potentials in the bulk. This indicates that the Fermi level on the UHV-cleaved (110) surface was pinned, presumably due to defects upon cleaving. We also observed higher potentials at atomic steps than on the terraces for both GaInP2 epitaxial layer and GaAs substrate. Combining scanning tunneling microscopy (STM) and SKPM measurements, we found that the potential height at steps of the GaAs substrate depends on the step direction, which is probably a direct result of unbalanced cations and anions at the steps.

  8. Full band structure LDA and kp calculations of optical spin-injection F. Nastos,1 J. Rioux,1 M. Strimas-Mackey,1 Bernardo S. Mendoza,2 and J. E. Sipe1

    E-Print Network [OSTI]

    Sipe,J. E.

    Full band structure LDA and k·p calculations of optical spin-injection F. Nastos,1 J. Rioux,1 M; published 20 November 2007 We present a study of optical electron spin-injection optical orientation in the bulk semiconductors GaAs, Si, and CdSe from direct optical excitation with circularly polarized light

  9. Spin injection and spin dynamics at the CuPc/GaAs interface studied with ultraviolet photoemission spectroscopy and two-photon photoemission spectroscopy

    E-Print Network [OSTI]

    Aeschlimann, Martin

    injection via Schottky contacts. Only recently, direct electrical spin injec- tion with organicSpin injection and spin dynamics at the CuPc/GaAs interface studied with ultraviolet photoemission show a highly efficient spin injection of hot electrons from GaAs into CuPc, demonstrating that spin

  10. Hindawi Publishing Corporation International Journal of Photoenergy

    E-Print Network [OSTI]

    Chow, Lee

    GaAs triple junction solar cell has been proposed and carried out. With the same illumination area is properly cited. A complex solar unit with microcrystalline silicon solar cells placed around the centered and intensity, the total resultant power shows that the excess microcrystalline silicon solar cells increase

  11. Curso de Vero IF-USP 22 de Fevereiro -2013

    E-Print Network [OSTI]

    Dias, Luis Gregório

    influentes no nosso dia-a-dia (interações nucleares, forças forte/fraca, etc). Energia cinética de elétrons e exemplo. Ga As Energy Cristal de GaAs Níveis de energia at

  12. Physica E 14 (2002) 166171 www.elsevier.com/locate/physe

    E-Print Network [OSTI]

    Ganichev, Sergey

    2002-01-01

    in the range from liquid helium to room temperature. Two pairs of ohmic contacts were centered along opposite. Photocurrent jx in (1 1 3)-grown GaAs QWs of Cs symmetry normalized by the light power P as a function of the phase angle ' deÿning helicity. pulsed NH3 laser optically pumped by a TEA CO2 laser which yields strong

  13. Field Testing of Nano-PCM Enhanced Building Envelope Components

    SciTech Connect (OSTI)

    Biswas, Kaushik; Childs, Phillip W; Atchley, Jerald Allen

    2013-08-01

    The U.S. Department of Energy s (DOE) Building Technologies Program s goal of developing high-performance, energy efficient buildings will require more cost-effective, durable, energy efficient building envelopes. Forty-eight percent of the residential end-use energy consumption is spent on space heating and air conditioning. Reducing envelope-generated heating and cooling loads through application of phase change material (PCM)-enhanced envelope components can facilitate maximizing the energy efficiency of buildings. Field-testing of prototype envelope components is an important step in estimating their energy benefits. An innovative phase change material (nano-PCM) was developed with PCM encapsulated with expanded graphite (interconnected) nanosheets, which is highly conducive for enhanced thermal storage and energy distribution, and is shape-stable for convenient incorporation into lightweight building components. During 2012, two test walls with cellulose cavity insulation and prototype PCM-enhanced interior wallboards were installed in a natural exposure test (NET) facility at Charleston, SC. The first test wall was divided into four sections, which were separated by wood studs and thin layers of foam insulation. Two sections contained nano-PCM-enhanced wallboards: one was a three-layer structure, in which nano-PCM was sandwiched between two gypsum boards, and the other one had PCM dispersed homogeneously throughout graphite nanosheets-enhanced gypsum board. The second test wall also contained two sections with interior PCM wallboards; one contained nano-PCM dispersed homogeneously in gypsum and the other was gypsum board containing a commercial microencapsulated PCM (MEPCM) for comparison. Each test wall contained a section covered with gypsum board on the interior side, which served as control or a baseline for evaluation of the PCM wallboards. The walls were instrumented with arrays of thermocouples and heat flux transducers. Further, numerical modeling of the walls containing the nano-PCM wallboards were performed to determine their actual impact on wall-generated heating and cooling loads. The models were first validated using field data, and then used to perform annual simulations using Typical Meteorological Year (TMY) weather data. This article presents the measured performance and numerical analysis to evaluate the energy-saving potential of the nano-PCM-enhanced building components.

  14. APPLIED PHYTO-REMEDIATION TECHNIQUES USING HALOPHYTES FOR OIL AND BRINE SPILL SCARS

    SciTech Connect (OSTI)

    M.L. Korphage; Bruce G. Langhus; Scott Campbell

    2003-03-01

    Produced salt water from historical oil and gas production was often managed with inadequate care and unfortunate consequences. In Kansas, the production practices in the 1930's and 1940's--before statewide anti-pollution laws--were such that fluids were often produced to surface impoundments where the oil would segregate from the salt water. The oil was pumped off the pits and the salt water was able to infiltrate into the subsurface soil zones and underlying bedrock. Over the years, oil producing practices were changed so that segregation of fluids was accomplished in steel tanks and salt water was isolated from the natural environment. But before that could happen, significant areas of the state were scarred by salt water. These areas are now in need of economical remediation. Remediation of salt scarred land can be facilitated with soil amendments, land management, and selection of appropriate salt tolerant plants. Current research on the salt scars around the old Leon Waterflood, in Butler County, Kansas show the relative efficiency of remediation options. Based upon these research findings, it is possible to recommend cost efficient remediation techniques for slight, medium, and heavy salt water damaged soil. Slight salt damage includes soils with Electrical Conductivity (EC) values of 4.0 mS/cm or less. Operators can treat these soils with sufficient amounts of gypsum, install irrigation systems, and till the soil. Appropriate plants can be introduced via transplants or seeded. Medium salt damage includes soils with EC values between 4.0 and 16 mS/cm. Operators will add amendments of gypsum, till the soil, and arrange for irrigation. Some particularly salt tolerant plants can be added but most planting ought to be reserved until the second season of remediation. Severe salt damage includes soil with EC values in excess of 16 mS/cm. Operators will add at least part of the gypsum required, till the soil, and arrange for irrigation. The following seasons more gypsum will be added and as the soil EC is reduced, plants can be introduced. If rapid remediation is required, a sufficient volume of topsoil, or sand, or manure can be added to dilute the local salinity, the bulk amendments tilled into the surface with added gypsum, and appropriate plants added. In this case, irrigation will be particularly important. The expense of the more rapid remediation will be much higher.

  15. Pigments with or without organic binder? A survey of wall painting techniques during Antiquity

    SciTech Connect (OSTI)

    Walter, P.

    1996-01-01

    The identification of ancient artistic techniques is based on laboratory studies and, for historical cases, also on literary sources. An analytical approach using the techniques of physical chemistry reveals the technical expertise of the artists, right at the dawn of art. In the case of prehistoric parietal art, we show that the artists prepared their pigments with different ground and mixed minerals. They applied their material onto the wall and the particles remained embedded in the superficial calcite layer. Later, the prehistoric people prepared a real paint with the proper pigment, an extender and an organic binder to fix the paint on the wall. During Antiquity, new techniques appear. The paint is applied to the natural or artificial wall and is executed, either directly or on a previously applied plaster. The aim of this paper is to describe the evolution of the techniques. The underlying chemistry provides some interesting clues on the technical choices. {copyright} {ital 1996 American Institute of Physics.}

  16. Infiltration from an impoundment for coal-bed natural gas, Powder River Basin, Wyoming: Evolution of water and sediment chemistry - article no. W06424

    SciTech Connect (OSTI)

    Healy, R.W.; Rice, C.A.; Bartos, T.T.; McKinley, M.P. [US Geological Survey, Lakewood, CO (United States). Denver Federal Center

    2008-06-15

    Development of coal-bed natural gas (CBNG) in the Powder River Basin, Wyoming, has increased substantially in recent years. Among environmental concerns associated with this development is the fate of groundwater removed with the gas. A preferred water-management option is storage in surface impoundments. A study was conducted on changes in water and sediment chemistry as water from an impoundment infiltrated the subsurface. Sediment cores were collected prior to operation of the impoundment and after its closure and reclamation. Suction lysimeters were used to collect water samples from beneath the impoundment. Large amounts of chloride (12,300 kg) and nitrate (13,500 kg as N), most of which accumulated naturally in the sediments over thousands of years, were released into groundwater by infiltrating water. Nitrate was more readily flushed from the sediments than chloride. If sediments at other impoundment locations contain similar amounts of chloride and nitrate, impoundments already permitted could release over 48 x 10{sup 6} kg of chloride and 52 x 10{sup 6} kg of nitrate into groundwater in the basin. A solute plume with total dissolved solid (TDS) concentrations at times exceeding 100,000 mg/L was created in the subsurface. TDS concentrations in the plume were substantially greater than those in the CBNG water (about 2300 mg/L) and in the ambient shallow groundwater (about 8000 mg/L). Sulfate, sodium, and magnesium are the dominant ions in the plume. The elevated concentrations are attributed to cation-exchange-enhanced gypsum dissolution. As gypsum dissolves, calcium goes into solution and is exchanged for sodium and magnesium on clays. Removal of calcium from solution allows further gypsum dissolution.

  17. Products of an Artificially Induced Hydrothermal System at Yucca Mountain

    SciTech Connect (OSTI)

    S. Levy

    2000-08-07

    Studies of mineral deposition in the recent geologic past at Yucca Mountain, Nevada, address competing hypotheses of hydrothermal alteration and deposition from percolating groundwater. The secondary minerals being studied are calcite-opal deposits in fractures and lithophysal cavities of ash-flow tuffs exposed in the Exploratory Studies Facility (ESF), a 7.7-km tunnel excavated by the Yucca Mountain Site Characterization Project within Yucca Mountain. An underground field test in the ESF provided information about the minerals deposited by a short-lived artificial hydrothermal system and an opportunity for comparison of test products with the natural secondary minerals. The heating phase lasted nine months, followed by a nine-month cooling period. Natural pore fluids were the only source of water during the thermal test. Condensation and reflux of water driven away from the heater produced fluid flow in certain fractures and intersecting boreholes. The mineralogic products of the thermal test are calcite-gypsum aggregates of less than 4-micrometer crystals and amorphous silica as glassy scale less than 0.2 mm thick and as mounds of tubules with diameters less than 0.7 micrometers. The minute crystal sizes of calcite and gypsum from the field test are very different from the predominantly coarser calcite crystals (up to cm scale) in natural secondary-mineral deposits at the site. The complex micrometer-scale textures of the amorphous silica differ from the simple forms of opal spherules and coatings in the natural deposits, even though some natural spherules are as small as 1 micrometer. These differences suggest that the natural minerals, especially if they were of hydrothermal origin, may have developed coarser or simpler forms during subsequent episodes of dissolution and redeposition. The presence of gypsum among the test products and its absence from the natural secondary-mineral assemblage may indicate a higher degree of evaporation during the test than during the deposition of natural calcite-opal deposits.

  18. Beneficial use of coal combustion products continues to grow

    SciTech Connect (OSTI)

    MacDonald, M.

    2008-07-01

    In August 2007 the American Coal Ash Association (ACAA) released results of the Coal Combustion Products Production (CCP) and use survey. Production was 124,795,000 tons while beneficial use was 54,203,000 tons, a utilization rate of over 43%, 3% higher than in 2005. The article includes graphs of 40 years of CCP production and use and projected trade of CCP utilization until 2011. It also gives 2006 figures for Production and use of fly ash, bottom ash, boiler slag, FGD gypsum and other FGD products, and FBC ash. 3 refs., 3 figs.

  19. ACAA 2006 fall meeting

    SciTech Connect (OSTI)

    2006-07-01

    The seven presentations (in pdf format) on the CD-ROM are: Amended Silicates{trademark}: mercury control without harming fly ash (J. Butz and others); benefits of gypsum in agriculture (L.D. Norton); co-firing biomass in pc fired units (C. Meijer and others); minimizing the impact of air pollution control equipment retrofits on saleability of fly ash (C.Weilert); new power plant construction - CCP readiness (T. Jansen); recent utilization of fly ash in coal plant construction (J. Liljegren and T. Hart); and resource conservation challenge (C. McLaughlin).

  20. Design of a Sustainable House for Residents of a Colonia in South Texas 

    E-Print Network [OSTI]

    Schoenemann, T. J.; Haberl, J. S.; Hill, R. C.

    2002-01-01

    ) and covering parking lots with porous paving rather than asphalt. ?The habitat roof is a third of what a normal drainage site might cost with gutters, down spouts and underground pipes," stated Tim O'Brien, vice- president of real estate for Ford Motor Land...Cabe?s findings, but this is considered a fairly primitive testing procedure. In 1996, Oak Ridge National Laboratory (ORNL) constructed a bale wall that was stuccoed on the cold side and covered with gypsum drywall on the warm side. This test found the R...

  1. The Sunflower, 1960-1986

    E-Print Network [OSTI]

    2015-01-01

    according to plan, law and order was reestablished, and "communism" was wiped out. Recently oil, salt, coal, and gypsum deposits have been discovered in Kansas and many companies from the USLA are negotiating with the Kansas government for exploitation... for a group of Kansans, a trip to an oil refinery or a pleasure trip to a beach? What is more educational, burying oneself in a library to write a paper on what other people have already said, or frolicking at a resort and talking with people in a...

  2. National Hydrogen Association | 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 QA:QA J-E-1 SECTION J APPENDIXsourceII Jump to: navigation, searchsourceEnergyTexas:NGEN8ModelingGypsum Jump

  3. National Hydropower Association | 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 QA:QA J-E-1 SECTION J APPENDIXsourceII Jump to: navigation, searchsourceEnergyTexas:NGEN8ModelingGypsum JumpHydropower

  4. National Institute for Environmental Studies (NIES) | Open Energy

    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 QA:QA J-E-1 SECTION J APPENDIXsourceII Jump to: navigation, searchsourceEnergyTexas:NGEN8ModelingGypsum

  5. National Institute of Energy Efficiency | 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 QA:QA J-E-1 SECTION J APPENDIXsourceII Jump to: navigation, searchsourceEnergyTexas:NGEN8ModelingGypsumNational

  6. National Iranian Oil Company | 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 QA:QA J-E-1 SECTION J APPENDIXsourceII Jump to: navigation, searchsourceEnergyTexas:NGEN8ModelingGypsumNationalIranian

  7. The Function of the Lipoxygenase ZmLOX10 in Maize Interactions with Insects and Pathogens 

    E-Print Network [OSTI]

    Christensen, Shawn A.

    2011-02-22

    -GAA-GCCAAC-GCC-AWC- GCC-TCY-A-3?) and the following ZmLOX10 gene-specific primers (61560 F 5?- CGC-TAG-CTT-AGC-CAC-CAG-TAG-TCC -3?; 61561 R GCG-CTG-GAA-GTA- CAT-CTG-CCC-GA; 61562 R GGA-AGC-GCA-GAT-CCT-TCT-TGT-TGA-TGA-G; 61563 F GCC-ATC-GGG-CAG-ATG-TAC-TTC-CAG; 61564 R... TAG-TCG-TAG- 31 ACG-CGC-TCG-AAC-ACC-TT; 61565 R AAC-TCC-TCG-TCC-TTG-AAC-CAC- GAG-AAC; 61566 F TTC-TCG-TGG-TTC-AAG-GAC-GAG-GAG-TTC; 61567 R CCT-CTG-CAT-GCA-ATA-ATA-GTA-CAC-CCC-C; 61568 F CGG-CTG-TTC-ATC- CTG-GAC-TAC-CAC; 61569 R CAG...

  8. Genetic relationships and evolutionary history of extant Bowhead whale populations, Balaena mysticetus 

    E-Print Network [OSTI]

    Huebinger, Ryan Michael

    2009-05-15

    53 EF538945 180-194 6 0.826 0.763 0.272 R-HEX-TTG CCA ATC CTT TTC TAT TGA TGG AT Bmy7 F-GAA ATT TGA AAC TAA TTT ATC CAT CGG (CA) 23 64-56 # EF538946 149-181 11 0.744 0.814 0.180 R-6-FAM-GCT TCA GCA AAG TTT TCA GTA GGA...-HEX-GCC CCA AGA GGA TTT CTC TGC A Bmy11 F-6-FAM-AAG GAA ACA ATC AGA ATA AGG TGT CC (CA) 33 50 EF538949 214-240 10 0.833 0.876 0.846 R-GCT GCC CTT CAT TCT CTC AAA AGC Bmy12 F-6-FAM-TTT GTC TCC CTG GGT AAC TTC TTG A (CA) 38 53 EF538950 115...

  9. Novel genes induce uterine receptivity: the characterization of a specific gene product in the ewe uterus 

    E-Print Network [OSTI]

    De Graauw, Jennifer Ann

    2013-02-22

    gct aat cag ggt cat cta aga agc tca tta aaa cag tga tta ctg acc cca ctc cca taa ttg ctc tgc tgg gca ggg gag aaa gac atg aga att tga att ttt caa aag ttc cta aac agt gct aat gtg gca gct ttg ggt acc aaa att tga gaa act ggg tgt agc atg cgt ttt gga ggt... aat ttc cag att ctc ctg tct cct tcc ttt ccc agg tgc tgg gcc tgg tgc ggg tgc ccc tgt ata ccc tgc gag atg gtg tgg gag gcc tgc ctg cct tcc tgg aga ata cct tta ttg gaa atg cac ggg aac agc tgg tgg aag ccg tcc aga acc tgg gac tgc tgg aac ctg gct ctt ttg...

  10. Deep level centers and their role in photoconductivity transients of InGaAs/GaAs quantum dot chains

    SciTech Connect (OSTI)

    Kondratenko, S. V. Vakulenko, O. V.; Mazur, Yu. I. Dorogan, V. G.; Marega, E.; Benamara, M.; Ware, M. E.; Salamo, G. J.

    2014-11-21

    The in-plane photoconductivity and photoluminescence are investigated in quantum dot-chain InGaAs/GaAs heterostructures. Different photoconductivity transients resulting from spectrally selecting photoexcitation of InGaAs QDs, GaAs spacers, or EL2 centers were observed. Persistent photoconductivity was observed at 80?K after excitation of electron-hole pairs due to interband transitions in both the InGaAs QDs and the GaAs matrix. Giant optically induced quenching of in-plane conductivity driven by recharging of EL2 centers is observed in the spectral range from 0.83?eV to 1.0?eV. Conductivity loss under photoexcitation is discussed in terms of carrier localization by analogy with carrier distribution in disordered media.

  11. Effective Field Theories for Electrons in Crystalline Structures

    E-Print Network [OSTI]

    Federico L. Bottesi; Guillermo R. Zemba

    2008-04-07

    We present an effective field theory formulation for a class of condensed matter systems with crystalline structures for which some of the discrete symmetries of the underlying crystal survive the long distance limit, up to mesoscopic scales, and argue that this class includes interesting materials, such as $Si$-doped $GaAs$. The surviving symmetries determine a limited set of possible effective interactions, that we analyze in detail for the case of $Si$-doped $GaAs$ materials. These coincide with the ones proposed in the literature to describe the spin relaxation times for the $Si$-doped $Ga As$ materials, obtained here as a consequence of the choice of effective fields and their symmetries. The resulting low-energy effective theory is described in terms of three (six chiral) one-dimensional Luttinger liquid systems and their corresponding intervalley transitions. We also discuss the Mott transition within the context of the effective theory.

  12. High-efficiency GaAs/Ge monolithic tandem solar cells

    SciTech Connect (OSTI)

    Tobin, S.P.; Vernon, S.M.; Bajgar, C.; Haven, V.E.; Geoffroy, L.M.; Lillington, D.R.

    1988-05-01

    High photovoltaic efficiency and light weight are important criteria for spacecraft power applications. Present GaAs cells are approaching their efficiency limits, but are not efficient or light enough for future needs. The authors have investigated tandem cells of GaAs grown by MOCVD on thin Ge to address both higher efficiency and reduced weight. GaAs/Ge monolithic tandem cells of 4-cm/sup 2/ area have been produced with independently verified efficiencies up to 21.7 percent (AMO, one sun, 25/sup 0/C, total area). Under AM1.5 Global conditions, efficiencies are up to 24.3 percent. These are the highest one-sun efficiencies reported for GaAs/Ge cells, and the highest efficiency for a two-terminal monolithic tandem cell.

  13. Comment on "Cyclotron resonance study of the electron and hole velocity in graphene monolayers"

    E-Print Network [OSTI]

    S. C. Tiwari

    2007-05-26

    In this comment it is pointed out that the electron velocity of the same order as observed in graphene had been measured in GaAs submicron devices long ago. Particle- antiparticle asymmetry related with electron and hole effective masses in graphene seems puzzling as hole in a condensed matter system cannot be treated as anti-electron. It is argued that there should be a universal electrodynamics for QHE and superconductivity. In this context attention is drawn to the new approach based on massless electron and the interpretation that magnetic field represents angular momentum of the photon fluid. Measurement of electron velocity in graphene and GaAs in parallel is suggested for testing the massless electrodynamics.

  14. Four-Terminal Mechanically Stacked GaAs/Si Tandem Solar Cells

    E-Print Network [OSTI]

    Hassan, S

    2015-01-01

    This study investigates a four-terminal mechanically stacked double junction photovoltaic device based on GaAs as a top subcell and Si as a bottom subcell. Unlike two terminal monolithically series connected double junction photovoltaics, four-terminal mechanically stacked devices benefit from the ability to choose a combination of materials that are not constrained to lattice matching condition. GaAs top subcell is the best sensitive to visible light and Si bottom subcell is chosen to be grown on Si substrate which has relatively low cost. Moreover, the carriers generated by each subcell is collected independently to the external circuit. This electrical isolation of the subcells ensures higher efficiency, where no current matching nor tunnel junctions and related losses exist. A conversion efficiency of the device with a thickness in the order of 10 microns surpassed 27%.

  15. Non-Destructive Spent Fuel Characterization with Semi-Conducting Gallium Arsinde Neutron Imaging Arrays

    SciTech Connect (OSTI)

    Douglas S. McGregor; Holly K. Gersch; Jeffrey D. Sanders; John C. Lee; Mark D. Hammig; Michael R. Hartman; Yong Hong Yang; Raymond T. Klann; Brian Van Der Elzen; John T. Lindsay; Philip A. Simpson

    2002-01-30

    High resistivity bulk grown GaAs has been used to produce thermal neutron imaging devices for use in neutron radiography and characterizing burnup in spent fuel. The basic scheme utilizes a portable Sb/Be source for monoenergetic (24 keV) neutron radiation source coupled to an Fe filter with a radiation hard B-coated pixellated GaAs detector array as the primary neutron detector. The coated neutron detectors have been tested for efficiency and radiation hardness in order to determine their fitness for the harsh environments imposed by spent fuel. Theoretical and experimental results are presented, showing detector radiation hardness, expected detection efficiency and the spatial resolution from such a scheme. A variety of advanced neutron detector designs have been explored, with experimental results achieving 13% thermal neutron detection efficiency while projecting the possibility of over 30% thermal neutron detection efficiency.

  16. Towards a graphene-based quantum impedance standard

    SciTech Connect (OSTI)

    Kalmbach, C.-C.; Schurr, J., E-mail: juergen.schurr@ptb.de; Ahlers, F. J.; Müller, A. [Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig (Germany); Novikov, S.; Lebedeva, N. [Department of Micro- and Nanosciences, Aalto University, Micronova, Tietotie 3, 02150 Espoo (Finland); Satrapinski, A. [MIKES, Tekniikantie 1, P.O. Box, 02151 Espoo (Finland)

    2014-08-18

    Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 10{sup 7}. This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-flux-dependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about ?8?×?10{sup ?8}/kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance.

  17. Wavelength controlled multilayer-stacked linear InAs quantum dot arrays on InGaAsP/InP (100) by self-organized anisotropic strain engineering: A self-ordered quantum dot crystal

    SciTech Connect (OSTI)

    Sritirawisarn, N.; Otten, F. W. M. van; Eijkemans, T. J.; Noetzel, R.

    2008-09-29

    Multilayer-stacked linear InAs quantum dot (QD) arrays are created on InAs/InGaAsP superlattice templates formed by self-organized anisotropic strain engineering on InP (100) substrates in chemical beam epitaxy. Stacking of the QD arrays with identical emission wavelength in the 1.55 {mu}m region at room temperature is achieved through the insertion of ultrathin GaAs interlayers beneath the QDs with increasing interlayer thickness in successive layers. The increment in the GaAs interlayer thickness compensates the QD size/wavelength increase during strain correlated stacking. This is the demonstration of a three-dimensionally self-ordered QD crystal with fully controlled structural and optical properties.

  18. Progress on a cryogenically cooled RF gun polarized electron source

    SciTech Connect (OSTI)

    Fliller, R.P., III; Edwards, H.; /Fermilab

    2006-08-01

    RF guns have proven useful in multiple accelerator applications. An RF gun capable of producing polarized electrons is an attractive electron source for the ILC or an electron-ion collider. Producing such a gun has proven elusive. The NEA GaAs photocathode needed for polarized electron production is damaged by the vacuum environment in an RF gun. Electron and ion back bombardment can also damage the cathode. These problems must be mitigated before producing an RF gun polarized electron source. In this paper we report continuing efforts to improve the vacuum environment in a normal conducting RF gun by cooling it with liquid nitrogen after a high temperature vacuum bake out. We also report on a design of a cathode preparation chamber to produce bulk GaAs photocathodes for testing in such a gun. Future directions are also discussed.

  19. Growth, steady-state, and time-resolved photoluminescence study of CdTe/MgCdTe double heterostructures on InSb substrates using molecular beam epitaxy

    SciTech Connect (OSTI)

    DiNezza, Michael J.; Liu, Shi; Kirk, Alexander P.; Zhang, Yong-Hang [Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States) [Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States); School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Zhao, Xin-Hao [Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States) [Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States); School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287 (United States)

    2013-11-04

    CdTe/MgCdTe double heterostructures (DHs) are grown on InSb substrates using molecular beam epitaxy and reveal strong photoluminescence with over double the intensity of a GaAs/AlGaAs DH with an identical layer structure design grown on GaAs. Time-resolved photoluminescence of the CdTe/MgCdTe DH gives a Shockley-Read-Hall recombination lifetime of 86 ns, which is more than one order of magnitude longer than that of typical polycrystalline CdTe films. These findings indicate that monocrystalline CdTe/MgCdTe DHs effectively reduce surface recombination, have limited nonradiative interface recombination, and are promising for solar cells that could reach power conversion efficiencies similar to that of GaAs.

  20. Composition profiling of GaAs/AlGaAs quantum dots grown by droplet epitaxy

    SciTech Connect (OSTI)

    Bocquel, J.; Koenraad, P. M. [Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands); Giddings, A. D.; Prosa, T. J.; Larson, D. J. [CAMECA Instruments, Inc., 5500 Nobel Drive, Madison, Wisconsin 53711 (United States); Mano, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-10-13

    Droplet epitaxy (DE) is a growth method which can create III-V quantum dots (QDs) whose optoelectronic properties can be accurately controlled through the crystallisation conditions. In this work, GaAs/AlGaAs DE-QDs have been analyzed with the complimentary techniques of cross-sectional scanning tunneling microscopy and atom probe tomography. Structural details and a quantitative chemical analysis of QDs of different sizes are obtained. Most QDs were found to be pure GaAs, while a small proportion exhibited high intermixing caused by a local etching process. Large QDs with a high aspect ratio were observed to have an Al-rich crown above the GaAs QD. This structure is attributed to differences in mobility of the cations during the capping phase of the DE growth.