Sample records for arsenide gaas gypsum

  1. Gallium Arsenide (GaAs) EDWARD D. PALIK

    E-Print Network [OSTI]

    Pulfrey, David L.

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

  2. 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

  3. FGD gypsum issues

    SciTech Connect (OSTI)

    Buecker, B.

    2007-11-15T23:59:59.000Z

    The article first explains how gypsum by-product is produced in flue gas desulfurization systems in coal-fired power plants. It goes on to talk about the main markets for gypsum - wallboard manufacture (Plaster of Paris), cement production and soil stabilization. In the USA in 2006 41.6 million tons of gypsum was used by manufacturers of wallboard and plaster products, 3.0 mt for cement production and 1.1 mt for agricultural purposes. A method of determining the by-product gypsum content by thermogravimetric analysis is outlined. 4 refs., 1 fig.

  4. 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

  5. Simple intrinsic defects in GaAs : numerical supplement.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2012-04-01T23:59:59.000Z

    This Report presents numerical tables summarizing properties of intrinsic defects in gallium arsenide, GaAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz and O.A. von Lilienfeld, 'Simple intrinsic defects in GaAs', Modelling Simul. Mater. Sci Eng., Vol. 17, 084007 (2009), and intended for use as reference tables for a defect physics package in device models. The numerical results for density functional theory calculations of properties of simple intrinsic defects in gallium arsenide are presented.

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

    SciTech Connect (OSTI)

    Muhammad, R.; Ahamad, R. [Sustainability Research Alliance, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Ibrahim, Z.; Othaman, Z. [Physic Department, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia)

    2014-03-05T23:59:59.000Z

    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.

  7. 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.

    2013-06-01T23:59:59.000Z

    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.

  8. 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 Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsum Jump to:

  9. 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 Hydrogen adsorption on the 2 4 and 4 2 reconstructions of gallium arsenide 001 has been studied by internal

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

    SciTech Connect (OSTI)

    Kraus, Tobias, E-mail: tobias.kraus@ise.fraunhofer.de; Höhn, Oliver; Hauser, Hubert; Bläsi, Benedikt [Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstr. 2, 79110 Freiburg (Germany)

    2014-02-07T23:59:59.000Z

    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.

  11. Use of waste gypsum to replace natural gypsum as set retarders in portland cement

    SciTech Connect (OSTI)

    Chandara, Chea; Azizli, Khairun Azizi Mohd [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Ahmad, Zainal Arifin [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)], E-mail: zainal@eng.usm.my; Sakai, Etsuo [Tokyo Institute of Technology, Graduate School of Science and Engineering, Department of Metallurgy and Ceramic Science, 2-12-1 Meguro-ku, Ookayama, Meguro-ku, Tokyo 152-8552 (Japan)

    2009-05-15T23:59:59.000Z

    The present study is focused on clarifying the influence of waste gypsum (WG) in replacing natural gypsum (NG) in the production of ordinary Portland cement (OPC). WG taken from slip casting moulds in a ceramic factory was formed from the hydration of plaster of paris. Clinker and 3-5 wt% of WG was ground in a laboratory ball mill to produce cement waste gypsum (CMWG). The same procedure was repeated with NG to substitute WG to prepare cement natural gypsum (CMNG). The properties of NG and WG were investigated via X-ray Diffraction (XRD), X-ray fluorescence (XRF) and differential scanning calorimetry (DSC)/thermogravimetric (TG) to evaluate the properties of CMNG and CMWG. The mechanical properties of cement were tested in terms of setting time, flexural and compressive strength. The XRD result of NG revealed the presence of dihydrate while WG contained dihydrate and hemihydrate. The content of dihydrate and hemihydrates were obtained via DSC/TG, and the results showed that WG and NG contained 12.45% and 1.61% of hemihydrate, respectively. Furthermore, CMWG was found to set faster than CMNG, an average of 15.29% and 13.67% faster for the initial and final setting times, respectively. This was due to the presence of hemihydrate in WG. However, the values obtained for flexural and compressive strength were relatively the same for CMNG and CMWG. Therefore, this result provides evidence that WG can be used as an alternative material to NG in the production of OPC.

  12. What You Need to Know About Gypsum

    E-Print Network [OSTI]

    Balser, Teri C.

    TestCa(ppm) Arlington Ashland Lancaster Spooner 0 100 200 300 400 500 600 700 SoilTestMg(ppm) Arlington Ashland applied (t/a) 5.8 6.0 6.2 6.4 6.6 6.8 7.0 SoilpH Arlington Ashland Lancaster Spooner 5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 SoilpH Arlington Ashland Lancaster Spooner 0 1 4 16 Effect of gypsum additions on soil p

  13. Flue gas desulfurization gypsum and fly ash

    SciTech Connect (OSTI)

    Not Available

    1992-05-01T23:59:59.000Z

    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.

  14. Properties study of cotton stalk fiber/gypsum composite

    SciTech Connect (OSTI)

    Li Guozhong; Yu Yanzhen; Zhao Zhongjian; Li Jianquan; Li Changchun

    2003-01-01T23:59:59.000Z

    This manuscript addresses treating cotton stalk fiber surface with styrene acrylic emulsion, which improves the interfacial combined state of cotton stalk fiber/gypsum composite effectively and improves its mechanical properties notably. Mixes less slag, ordinary Portland cement, etc., to modify gypsum base. The electron microscope was utilized to analyze and research on the effect on composite properties of the abovementioned mixtures.

  15. E-Print Network 3.0 - actively forming gypsum Sample Search Results

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

    for formation of gypsum) for the reference solution... by ICP-mass spectroscopy analysis for calcium. 4. Results and discussion Gypsum scale can form due... of...

  16. E-Print Network 3.0 - arsenide superconductors including Sample...

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

    arsenides may have several competing... The high-temperature iron-arsenide FeAs superconduct- ors Fig. 1 a Refs. 1 and 2 exhibit a similar... -oxygen compounds and the iron...

  17. Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials

    DOE Patents [OSTI]

    Hogan, S.J.

    1983-03-13T23:59:59.000Z

    Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

  18. Investigation on properties of ultrafast switching in a bulk gallium arsenide avalanche semiconductor switch

    SciTech Connect (OSTI)

    Hu, Long, E-mail: hulong-1226@126.com [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049 (China); Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China); Su, Jiancang; Ding, Zhenjie; Hao, Qingsong; Yuan, Xuelin [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi'an 710024 (China)

    2014-03-07T23:59:59.000Z

    Properties of ultrafast switching in a bulk gallium arsenide (GaAs) avalanche semiconductor switch based on semi-insulating wafer, triggered by an optical pulse, were analyzed using physics-based numerical simulations. It has been demonstrated that when a voltage with amplitude of 5.2?kV is applied, after an exciting optical pulse with energy of 1??J arrival, the structure with thickness of 650??m reaches a high conductivity state within 110 ps. Carriers are created due to photons absorption, and electrons and holes drift to anode and cathode terminals, respectively. Static ionizing domains appear both at anode and cathode terminals, and create impact-generated carriers which contribute to the formation of electron-hole plasma along entire channel. When the electric field in plasma region increases above the critical value (?4?kV/cm) at which the electrons drift velocity peaks, a domain comes into being. An increase in carrier concentration due to avalanche multiplication in the domains reduces the domain width and results in the formation of an additional domain as soon as the field outside the domains increases above ?4?kV/cm. The formation and evolution of multiple powerfully avalanching domains observed in the simulations are the physical reasons of ultrafast switching. The switch exhibits delayed breakdown with the characteristics affected by biased electric field, current density, and optical pulse energy. The dependence of threshold energy of the exciting optical pulse on the biased electric field is discussed.

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

    SciTech Connect (OSTI)

    Jessica Marshall Sanderson

    2006-06-01T23:59:59.000Z

    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

  20. E-Print Network 3.0 - americium arsenides Sample Search Results

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

    Summary: of gallium arsenide, a semiconductor, which is used in advanced optoelectronics, lasers, microwave circuits... , and solar cells. To determine material...

  1. E-Print Network 3.0 - arsenide- gallium instrument Sample Search...

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

    Summary: of gallium arsenide, a semiconductor, which is used in advanced optoelectronics, lasers, microwave circuits... , and solar cells. To determine material...

  2. E-Print Network 3.0 - arsenide junction-field-effect transistors...

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

    technique holds Summary: arsenide chips manufactured in multilayer stacks: light sensors, high-speed transistors and solar cells... material available. For example, the...

  3. E-Print Network 3.0 - aluminium arsenide solar cells Sample Search...

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

    manufacturing technique holds Summary: arsenide chips manufactured in multilayer stacks: light sensors, high-speed transistors and solar cells... the photovoltaic cells that solar...

  4. Characteristics of trap-filled gallium arsenide photoconductive switches used in high gain pulsed power applications

    SciTech Connect (OSTI)

    ISLAM,N.E.; SCHAMILOGLU,E.; MAR,ALAN; LOUBRIEL,GUILLERMO M.; ZUTAVERN,FRED J.; JOSHI,R.P.

    2000-05-30T23:59:59.000Z

    The electrical properties of semi-insulating (SI) Gallium Arsenide (GaAs) have been investigated for some time, particularly for its application as a substrate in microelectronics. Of late this material has found a variety of applications other than as an isolation region between devices, or the substrate of an active device. High resistivity SI GaAs is increasingly being used in charged particle detectors and photoconductive semiconductor switches (PCSS). PCSS made from these materials operating in both the linear and non-linear modes have applications such as firing sets, as drivers for lasers, and in high impedance, low current Q-switches or Pockels cells. In the non-linear mode, it has also been used in a system to generate Ultra-Wideband (UWB) High Power Microwaves (HPM). The choice of GaAs over silicon offers the advantage that its material properties allow for fast, repetitive switching action. Furthermore photoconductive switches have advantages over conventional switches such as improved jitter, better impedance matching, compact size, and in some cases, lower laser energy requirement for switching action. The rise time of the PCSS is an important parameter that affects the maximum energy transferred to the load and it depends, in addition to other parameters, on the bias or the average field across the switch. High field operation has been an important goal in PCSS research. Due to surface flashover or premature material breakdown at higher voltages, most PCSS, especially those used in high power operation, need to operate well below the inherent breakdown voltage of the material. The lifetime or the total number of switching operations before breakdown, is another important switch parameter that needs to be considered for operation at high bias conditions. A lifetime of {approximately} 10{sup 4} shots has been reported for PCSS's used in UWB-HPM generation [5], while it has exceeded 10{sup 8} shots for electro-optic drivers. Much effort is currently being channeled in the study related to improvements of these two parameters high bias operation and lifetime improvement for switches used in pulsed power applications. The contact material and profiles are another important area of study. Although these problems are being pursued through the incorporation of different contact materials and introducing doping near contacts, it is important that the switch properties and the conduction mechanism in these switches be well understood such that the basic nature of the problems can be properly addressed. In this paper the authors report on these two basic issues related to the device operation, i.e., mechanisms for increasing the hold-off characteristics through neutron irradiation, and the analysis of transport processes at varying field conditions in trap dominated SI GaAs in order to identify the breakdown mechanism during device operation. It is expected that this study would result in a better understanding of photoconductive switches, specifically those used in high power operation.

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

    SciTech Connect (OSTI)

    Jessica Sanderson

    2007-12-31T23:59:59.000Z

    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

  6. Department of Mechanical Engineering Spring 2013 CFD Model of a Gypsum Mixer

    E-Print Network [OSTI]

    Demirel, Melik C.

    PENNSTATE Department of Mechanical Engineering Spring 2013 CFD Model of a Gypsum Mixer Overview This project, in continuation of last semester's team, intends to create a computational fluid dynamic (CFD) model of the fluid flow inside CertainTeed Gypsum's gypsum mixer. Currently, the mixer outputs locally

  7. IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption

    E-Print Network [OSTI]

    Grandidier, Jonathan

    IEEE JOURNAL OF PHOTOVOLTAICS, VOL. 2, NO. 2, APRIL 2012 123 Gallium Arsenide Solar Cell Absorption--Gallium arsenide, nanospheres, photovoltaic systems, whispering gallery modes (WGMs). I. INTRODUCTION THE route as the active layer is thinned [2]. Thin-film photovoltaics offer the possibility to significantly reduce

  8. 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.

    2010-05-23T23:59:59.000Z

    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.

  9. Gamma doses from phospho-gypsum plaster-board

    SciTech Connect (OSTI)

    O`Brien, R.S. [Australian Radiation Lab., Victoria (Australia)

    1997-01-01T23:59:59.000Z

    The use of phospho-gypsum plaster-board and plaster cement in buildings as a substitute for natural gypsum may constitute an additional source of radiation exposure to both workers and members of the public, both from inhalation of radon progeny produced from radon which is exhaled from the plaster-board and from beta and gamma radiation produced by radioactive decay in the plaster-board. The calculations presented in this paper indicate that if phospho-gypsum sheets 1 cm thick containing a {sup 226}Ra concentration of 400 Bq kg{sup -1} are used to line the walls and ceiling of a room of dimensions up to 5 m {times} 5 m {times} 3 m, the annual effective dose from gamma radiation for a person continually occupying the room should not exceed approximately 0.13 mSv. This compares with a measured annual average effective dose from gamma radiation in Australian homes of 0.9 mSv. The annual effective dose from such thin sheets is directly proportional to the {sup 226}Ra concentration in the plaster-board. 13 refs., 6 figs.

  10. Fabrication of optoelectronic microwave linear and ring resonators on a gallium arsenide substrate

    E-Print Network [OSTI]

    Yeh, Chun-Liang

    1993-01-01T23:59:59.000Z

    FABRICATION OF OPTOELECTRONIC MICROWAVE LINEAR AND RING RESONATORS ON A GALLIUM ARSENIDE SUBSTRATE A Thesis by CHUN-LIANG YEH Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1993 Major Subject: Electrical Engineering FABRICATION OF OPTOELECTRONIC MICROWAVE LINEAR AND RING RESONATORS ON A GALLIUM ARSENIDE SUBSTRATE A Thesis by CHUN-LIANG YEH Approved as to style and content by: Mark...

  11. First principles predictions of intrinsic defects in aluminum arsenide, AlAs : numerical supplement.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2012-04-01T23:59:59.000Z

    This Report presents numerical tables summarizing properties of intrinsic defects in aluminum arsenide, AlAs, as computed by density functional theory. This Report serves as a numerical supplement to the results published in: P.A. Schultz, 'First principles predictions of intrinsic defects in Aluminum Arsenide, AlAs', Materials Research Society Symposia Proceedings 1370 (2011; SAND2011-2436C), and intended for use as reference tables for a defect physics package in device models.

  12. EFFECT OF GYPSUM ON AVAILABLE PHOSPHORUS EVALUATED BY MEHLICH-1, ION EXCHANGE RESIN, AND Pi-PAPER IN A BRAZILIAN TROPICAL OXISOL

    E-Print Network [OSTI]

    Silva, Rodrigo Coqui da; Chien, Sen Hsuing; Prochnow, Luís Ignácio

    2009-01-01T23:59:59.000Z

    Pure gypsum Source average Phosphate Rock (100 mg kg -1 P)Pure gypsum Source average Phosphate Rock (100 mg kg -1 P) bPure gypsum Source average Phosphate Rock (100 mg kg -1 P)

  13. Z .Geoderma 96 2000 4761 The terminology and the concepts of gypsum-rich

    E-Print Network [OSTI]

    Ahmad, Sajjad

    earth-surface processes. q 2000 Elsevier Science B.V. All rights reserved. Keywords: gypsum; gypsiferous of soils and surficial formations containing gypsum is rarely considered in the global environmental December 1999 Abstract Many terms in earth sciences, and their underlying ideas, have been developed

  14. Aluminum arsenide cleaved-edge overgrown quantum wires T. Zibold, D. Schuh, M. Bichler, F. Ertl, G. Abstreiter, and M. Grayson

    E-Print Network [OSTI]

    Grayson, Matthew

    Aluminum arsenide cleaved-edge overgrown quantum wires J. Moser,a T. Zibold, D. Schuh, M. Bichler measurements in quantum wires made of aluminum arsenide, a heavy-mass, multivalley one-dimensional 1D system, and G0=2e2 /h was observed in the presence of disorder.3 Aluminum arsenide AlAs is an alternate heavy

  15. Self-aligned submicron gate length gallium arsenide MESFET

    E-Print Network [OSTI]

    Huang, Hsien-Ching

    2012-06-07T23:59:59.000Z

    -biaserl saturation currents of 396. 67 + 83. 984 IzA were obtained for the transistors. Built- in voltages of 0. 8198 6 0. 007 V and ideality factors of 1. 456 6 0. 0079 were obtained for the Schottky diodes. The effect of gate length on transcond ictance... Geometrical and physical origins for the small signal equivalent circuit of FET Developed fabrication process for submicron gate length GaAs MESFET Transistor and Schottky diode mask patterns 10 13 15 16 18 19 21 23 23 25 25 32 34 18. Process...

  16. Oxidation of North Dakota scrubber sludge for soil amendment and production of gypsum. Final report

    SciTech Connect (OSTI)

    Hassett, D.J.; Moe, T.A.

    1997-10-01T23:59:59.000Z

    Cooperative Power`s Coal Creek Station (CCS) the North Dakota Industrial Commission, and the US Department of Energy provided funds for a research project at the Energy and Environmental Research Center. The goals of the project were (1) to determine conditions for the conversion of scrubber sludge to gypsum simulating an ex situ process on the laboratory scale; (2) to determine the feasibility of scaleup of the process; (3) if warranted, to demonstrate the ex situ process for conversion on the pilot scale; and (4) to evaluate the quality and handling characteristics of the gypsum produced on the pilot scale. The process development and demonstration phases of this project were successfully completed focusing on ex situ oxidation using air at low pH. The potential to produce a high-purity gypsum on a commercial scale is excellent. The results of this project demonstrate the feasibility of converting CCS scrubber sludge to gypsum exhibiting characteristics appropriate for agricultural application as soil amendment as well as for use in gypsum wallboard production. Gypsum of a purity of over 98% containing acceptable levels of potentially problematic constituents was produced in the laboratory and in a pilot-scale demonstration.

  17. Iron Arsenides--The New Family of High TC Magnetic Superconductors

    E-Print Network [OSTI]

    Weston, Ken

    Iron Arsenides--The New Family of High TC Magnetic Superconductors Jeff Lynn NIST Center Superconductors · (Brief) History of Magnetic Superconductors ­ Magnetic Impurities ­ Long Range Magnetic Order: Coexistence and Competition · Cuprate Superconductors--Highly Correlated Electron Systems ­ Undoped systems

  18. Two-photon photovoltaic effect in gallium arsenide Jeff Chiles,1

    E-Print Network [OSTI]

    Fathpour, Sasan

    Two-photon photovoltaic effect in gallium arsenide Jichi Ma,1 Jeff Chiles,1 Yagya D. Sharma,2 214669); published September 4, 2014 The two-photon photovoltaic effect is demonstrated in gallium; (230.0250) Optoelectronics; (040.5350) Photovoltaic; (130.4310) Nonlinear. http://dx.doi.org/10.1364/OL

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

    SciTech Connect (OSTI)

    Osses-Márquez, Juan; Calderón-Muñoz, Williams R., E-mail: wicalder@ing.uchile.cl [Department of Mechanical Engineering, University of Chile, Beauchef 850, Santiago (Chile)

    2014-10-21T23:59:59.000Z

    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.

  20. Estimates of inhalation doses resulting from the possible use of phospho-gypsum plaster-board in Australian homes

    SciTech Connect (OSTI)

    O`Brien, R.S.; Peggie, J.R.; Leith, I.S. [Australian Radiation Laboratory, Victoria (Australia)

    1995-04-01T23:59:59.000Z

    Current materials used as internal lining in Australian buildings ade based on natural gypsum of low radium content. A study was carried out to estimate the contribution to the annual effective dose due to airborne contamination from chemical by-product gypsum plaster board of higher radium content if it were used as an internal lining.

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

    E-Print Network [OSTI]

    Galay, Karma

    2008-01-01T23:59:59.000Z

    impacts which the author of the study is not Impact Analysis of Khothagpa Gypsum Mine 71 familiar with, only obvious ones are reported below. i) Air pollution Dusts generated by various mining activities are of major concern to the people living... 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...

  2. Dynamics of formation of photoresponse in a detector structure made of gallium arsenide

    SciTech Connect (OSTI)

    Ayzenshtat, G. I., E-mail: ayzen@mail.tomsknet.ru; Lelekov, M. A.; Tolbanov, O. P. [Tomsk State University (Russian Federation)

    2008-04-15T23:59:59.000Z

    The influence of capture effects on the characteristics of detectors of the ionizing radiation based on semi-insulating gallium arsenide is considered. Generation of nonequilibrium electrons and holes along the entire thickness of the active region was performed under illumination with an infrared light-emitting diode with a wavelength of 0.9 {mu}m. In this case, the situation emerging in the device structure under the effect of X-ray radiation or a high-energy electron beam was simulated. It is shown that the variation in the shape of the output signal with time in this case is caused by variation in the electric field profile due to the capture of holes at deep centers in gallium arsenide. An absolutely different distribution of the electric field emerges in the structure under irradiation of a semitransparent cathode of the structure with a red light-emitting diode, emission of which penetrates into the active region for mere 1 {mu}m. In this case, the transformation of the electric field is caused by the capture of electrons. Under the prolonged effect of such radiation, a space-charge-limited current mode emerges in the device.

  3. Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride by metalorganic vapor-phase epitaxy

    E-Print Network [OSTI]

    Li, Lian

    Formation of etch pits during carbon doping of gallium arsenide with carbon tetrachloride to examine the effects of carbon tetrachloride concentration and temperature on the morphology of carbon with increasing carbon tetrachloride concentration. Step bunching and pinning was observed at a IV/III ratio

  4. GyPSuM: A Detailed Tomographic Model of Mantle Density and Seismic Wave Speeds

    SciTech Connect (OSTI)

    Simmons, N A; Forte, A M; Boschi, L; Grand, S P

    2010-03-30T23:59:59.000Z

    GyPSuM is a tomographic model fo mantle seismic shear wave (S) speeds, compressional wave (P) speeds and detailed density anomalies that drive mantle flow. the model is developed through simultaneous inversion of seismic body wave travel times (P and S) and geodynamic observations while considering realistic mineral physics parameters linking the relative behavior of mantle properties (wave speeds and density). Geodynamic observations include the (up to degree 16) global free-air gravity field, divergence of the tectonic plates, dynamic topography of the free surface, and the flow-induced excess ellipticity of the core-mantle boundary. GyPSuM is built with the philosophy that heterogeneity that most closely resembles thermal variations is the simplest possible solution. Models of the density field from Earth's free oscillations have provided great insight into the density configuration of the mantle; but are limited to very long-wavelength solutions. Alternatively, simply scaling higher resolution seismic images to density anomalies generates density fields that do not satisfy geodynamic observations. The current study provides detailed density structures in the mantle while directly satisfying geodynamic observations through a joint seismic-geodynamic inversion process. Notable density field observations include high-density piles at the base of the superplume structures, supporting the fundamental results of past normal mode studies. However, these features are more localized and lower amplitude than past studies would suggest. When we consider all seismic anomalies in GyPSuM, we find that P and S-wave speeds are strongly correlated throughout the mantle. However, correlations between the high-velocity S zones in the deep mantle ({approx} 2000 km depth) and corresponding P-wave anomalies are very low suggesting a systematic divergence from simplified thermal effects in ancient subducted slab anomalies. Nevertheless, they argue that temperature variations are the primary cause of P-wave, S-wave, and density anomalies in the mantle.

  5. Field dependent emission rates in radiation damaged GaAs

    SciTech Connect (OSTI)

    Fleming, R. M.; Myers, S. M.; Wampler, W. R.; Lang, D. V.; Seager, C. H.; Campbell, J. M. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1415 (United States)

    2014-07-07T23:59:59.000Z

    We have measured the temperature and field dependence of emission rates from five traps in electron damaged GaAs. Four of the traps have previously been identified as radiation defects. One of the traps, seen in higher doped diodes, has not been previously identified. We have fit the data to a multiphonon emission theory that allows recombination in GaAs to be characterized over a broad range of temperature and electric field. These results demonstrate an efficient method to calculate field-dependent emission rates in GaAs.

  6. In-Plane Electronic Anisotropy of Underdoped ___122___ Fe-Arsenide Superconductors Revealed by Measurements of Detwinned Single Crystals

    SciTech Connect (OSTI)

    Fisher, Ian Randal

    2012-05-08T23:59:59.000Z

    The parent phases of the Fe-arsenide superconductors harbor an antiferromagnetic ground state. Significantly, the Neel transition is either preceded or accompanied by a structural transition that breaks the four fold symmetry of the high-temperature lattice. Borrowing language from the field of soft condensed matter physics, this broken discrete rotational symmetry is widely referred to as an Ising nematic phase transition. Understanding the origin of this effect is a key component of a complete theoretical description of the occurrence of superconductivity in this family of compounds, motivating both theoretical and experimental investigation of the nematic transition and the associated in-plane anisotropy. Here we review recent experimental progress in determining the intrinsic in-plane electronic anisotropy as revealed by resistivity, reflectivity and ARPES measurements of detwinned single crystals of underdoped Fe arsenide superconductors in the '122' family of compounds.

  7. Accurate characterization and improvement of GaAs microstrip attenuation

    E-Print Network [OSTI]

    Carroll, James Mason

    2012-06-07T23:59:59.000Z

    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...

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

    E-Print Network [OSTI]

    Chessman, Dennis John

    2004-09-30T23:59:59.000Z

    that used 0, 5, and 10 Mg ha-1 of gypsum only. Field studies were concluded 41 and 45 months after treatment application at the two locations. No effect of material on alfalfa yield or tissue mineral concentration was observed. Also, rate did not affect...

  9. Organometallic vapor-phase homoepitaxy of gallium arsenide assisted by a downstream hydrogen afterglow plasma in the growth region

    E-Print Network [OSTI]

    Collins, George J.

    of the trimeth- ylgallium (TMGa) for homoepitaxial GaAs. They found in direct comparison of the pure thermal-insulating) substrate is loaded into the depo- sition reactor of Fig. 1 without any chemical degreasing or polishing

  10. Heat treatment of bulk gallium arsenide using a phosphosilicate glass cap

    SciTech Connect (OSTI)

    Mathur, G.; Wheaton, M.L.; Borrego, J.M.; Ghandhi, S.K.

    1985-05-15T23:59:59.000Z

    n-type bulk GaAs crystals, capped with chemically vapor-deposited phosphosilicate glass, were heat treated at temperatures in the range of 600 to 950 /sup 0/C. Measurements on Schottky diodes and solar cells fabricated on the heat-treated material, after removal of a damaged surface layer, show an increase in free-carrier concentration, in minority-carrier-diffusion length, and in solar-cell short-circuit current. The observed changes are attributed to a removal of lifetime-reducing acceptorlike impurities, defects, or their complexes.

  11. Gallium arsenide-based ternary compounds and multi-band-gap solar cell research

    SciTech Connect (OSTI)

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

    1993-02-01T23:59:59.000Z

    Aim of this contract is the achievement of a high-efficiency, low-cost solar cell. The basic approach to the problem is centered upon the heteroepitaxial growth of a III-V compound material onto a single-crystal silicon wafer. The growth technique employed is metalorganic chemical vapor deposition. The silicon wafer may serve as a mechanical substrate and ohmic contact for a single-junction device, or may contain a p-n junction of its own and form the bottom cell of a two junction tandem solar cell structure. The III-V material for the single-junction case is GaAs and for the two-junction case is either GaAlAs or GaAsP, either material having the proper composition to yield a band gap of approximately 1.7 eV. Results achieved in this contract include the following: (1) a 17.6% efficient GaAs-on-Si solar cell; (2) an 18.5% efficient GaAs-on-Si concentrator solar cell at 400 suns; (3) a 24.8% efficient GaAs-on-GaAs solar cell; (4) a 28.7% efficient GaAs-on-GaAs concentrator solar cell at 200 suns; (5) measurement of the effects of dislocation density and emitter doping on GaAs cells; and (6) improvements in the growth process to achieve reproducible thin AlGaAs window layers with low recombination velocities and environmental stability.

  12. Ga nanoparticle-enhanced photoluminescence of GaAs

    SciTech Connect (OSTI)

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

    2013-09-02T23:59:59.000Z

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

  13. Recovery and utilization of gypsum and limestone from scrubber sludge. [Quarterly] technical report, March 1, 1993--May 31, 1993

    SciTech Connect (OSTI)

    Kawatra, S.K.; Eisele, T.C. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Metallurgical and Materials Engineering

    1993-09-01T23:59:59.000Z

    Wet flue-gas desulfurization units in coal-fired power plants produce a large amount of sludge which must be disposed of, and which is currently landfilled in most cases. Increasing landfill costs are gradually forcing utilities to find other alternatives. In principle, this sludge can be used to make gypsum (CaSO{sub 4}-2H{sub 2}O) for products such as plaster-of-Paris and wallboard, but only if impurities such as unreacted limestone and soluble salts are removed, and the calcium sulfite (CaSO{sub 3}) is oxidized to calcium sulfate (CaSO{sub 4}). This project is investigating methods for removing the impurities from the sludge so that high-quality, salable gypsum products can be made. Work done in the previous quarter concentrated on developing a low-cost froth flotation process that could remove limestone, unburned carbon, and related contaminants from the sludge while recovering the bulk of the calcium sulfite and gypsum. In the current quarter, experiments to remove impurities from the sludge using a water-only cyclone were conducted. The cyclone has been found to be effective for removing the coarser limestone impurities, as well as removing contaminants such as fine gravel and grinding-ball chips. These results show that the cyclone will be very complementary with froth flotation, which mainly removes the very fine impurities.

  14. Recovery and utilization of gypsum and limestone from scrubber sludge. Technical report, December 1, 1992--February 28, 1993

    SciTech Connect (OSTI)

    Kawatra, S.K.; Eisele, T.C. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Metallurgical and Materials Engineering; Banerjee, D. [Illinois Clean Coal Inst., Carterville, IL (United States)

    1993-05-01T23:59:59.000Z

    Wet flue-gas desulfurization units in coal-fired power plants produce a large amount of sludge which must be disposed of, and which is currently landfilled in most cases. Increasing landfill costs are gradually forcing utilities to find other alternatives. In principle, this sludge can be used to make gypsum (CaSO{sub 4}-2H{sub 2}O) for products such as plaster-of-Paris and wallboard, but only if impurities such as unreacted limestone and soluble salts are removed, and the calcium sulfite (CaSO{sub 3}) is oxidized to calcium sulfate (CaSO{sub 4}). This project is investigating methods for removing the impurities from the sludge so that high-quality, salable gypsum products can be made. Work done in the previous quarter concentrated on developing a dependable technique for analysis of scrubber sludge, so that it would be possible to determine exactly how well a particular purification process was working. This technique was then used to characterize the sludge from a particular Illinois power station. In the current quarter, studies were carried out using froth flotation to produce a product that could be oxidized to high-purity gypsum. These experiments have been quite successful, due to certain properties of the limestone impurity that makes it easier to remove by this method than was expected.

  15. The Hall mobility measurement of Liquid Phase Epitaxy grown aluminum gallium arsenide

    E-Print Network [OSTI]

    Choi, Young-Shig

    2012-06-07T23:59:59.000Z

    allows lasing action at or above room temperature. The utility of AI?Ga& ?As is based on the close latti&e match to GaAs over a range of Al mole fraction between zero and one(Fig. 1)IS). This is significant since heterojunctions between s...-type by occupying the site normally orc?pi& d by th& gro?p V element, ar?l acting as a donor. For the p-type of AI?Ga& ?As. %1g was used as an i&np?ri&y. Fig. 10 and Fig. 11 show I he r&'lal ionship bet wc?n th& in&p?r&I& & o???& r?t ?&n??&l t he alorr&i& weight...

  16. The reaction of carbon tetrachloride with gallium arsenide ,,001... L. Li., S, Gan, B.-K. Han, H. Qi, and R. F. Hicksa)

    E-Print Network [OSTI]

    Li, Lian

    The reaction of carbon tetrachloride with gallium arsenide ,,001... L. Li., S, Gan, B.-K. Han, H, California 90095 Received 26 June 1997; accepted for publication 30 December 1997 Carbon tetrachloride of steps during the vapor-phase epitaxial growth of III­V compound semiconductors.3,4 Carbon tetrachloride

  17. Response of GaAs to fast intense laser pulses

    E-Print Network [OSTI]

    Graves, JS; Allen, Roland E.

    1998-01-01T23:59:59.000Z

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

  18. Ballistic thermal point contacts made of GaAs nanopillars

    SciTech Connect (OSTI)

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

    2013-12-04T23:59:59.000Z

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

  19. High-quality InP on GaAs

    E-Print Network [OSTI]

    Quitoriano, Nathaniel Joseph

    2006-01-01T23:59:59.000Z

    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, ...

  20. 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.

    2011-03-28T23:59:59.000Z

    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.

  1. An experiment to test the viability of a gallium-arsenide cathode in a SRF electron gun

    SciTech Connect (OSTI)

    Kewisch,J.; Ben-Zvi, I.; Rao, T.; Burrill, A.; Pate, D.; Wu, Q.; Todd, R.; Wang, E.; Bluem, H.; Holmes, D.; Schultheiss, T.

    2009-05-04T23:59:59.000Z

    Strained gallium arsenide cathodes are used in electron guns for the production of polarized electrons. In order to have a sufficient quantum efficiency lifetime of the cathode the vacuum in the gun must be 10{sup -11} Torr or better, so that the cathode is not destroyed by ion back bombardment or through contamination with residual gases. All successful polarized guns are DC guns, because such vacuum levels can not be obtained in normal conducting RF guns. A superconductive RF gun may provide a sufficient vacuum level due to cryo-pumping of the cavity walls. We report on the progress of our experiment to test such a gun with normal GaAs-Cs crystals.

  2. Recovery and utilization of gypsum and limestone from scrubber sludge. Final technical report, September 1, 1992--August 31, 1993

    SciTech Connect (OSTI)

    Kawatra, S.K.; Eisele, T.C. [Michigan Technological Univ., Houghton, MI (United States). Dept. of Metallurgical and Materials Engineering

    1993-12-31T23:59:59.000Z

    Wet flue-gas desulfurization units in coal-fired power plants produce a large amount of sludge which must be disposed of, and which is currently landfilled in most cases. Increasing landfill costs are gradually forcing utilities to find other alternatives. In principle, this sludge can be used to make gypsum (CaSO{sub 4}{center_dot}2H{sub 2}O) for products such as plaster-of-Paris and wallboard, but only if impurities such as unreacted limestone and soluble salts are removed, and the calcium sulfite (CaSO{sub 3}) is oxidized to calcium sulfate (CaSO{sub 4}). This project investigated methods for removing the impurities from the sludge so that high-quality, salable gypsum products can be made. Two processes were studied, both separately and in combination: Water-only cycloning, and froth flotation. A large fraction (30--40%) of the impurities in the sludge are contained in the coarser, higher-density particles, which are readily removed using a water-only cyclone. Much of the remaining impurities are hydrophobic, and can be removed by froth flotation. A combined cyclone/froth flotation process has been found to be suitable for producing a high-purity product from scrubber sludge at low cost.

  3. 2=picosecond, GaAs photodiode optoelectronic circuit for optical correlation applications

    E-Print Network [OSTI]

    Ozbay, Ekmel

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

  4. Photorefractive measurements in electron irradiated semi-insulating GaAs

    E-Print Network [OSTI]

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

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

    E-Print Network [OSTI]

    Guill, Dennis Jarrett

    2012-06-07T23:59:59.000Z

    . 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...

  6. 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 solar cell under direct sunlight, light is received from the solar disk, but is re-emitted isotropically.1038/lsa.2013.1; published online 4 January 2013 Keywords: detailed balance; GaAs solar cell; light

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

    E-Print Network [OSTI]

    Atwater, Harry

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

  8. Free carrier induced spectral shift for GaAs filled metallic hole arrays

    E-Print Network [OSTI]

    New Mexico, University of

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

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

    SciTech Connect (OSTI)

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

    2010-10-04T23:59:59.000Z

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

  10. Quantum effects in electron beam pumped GaAs

    SciTech Connect (OSTI)

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

    2013-08-19T23:59:59.000Z

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

  11. Back contacted and small form factor GAAS solar cell.

    SciTech Connect (OSTI)

    Clews, Peggy Jane; Wanlass, Mark W. (National Renewable Energy Laboratory); Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

    2010-06-01T23:59:59.000Z

    We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

  12. 26. 1% solar cell efficiency for Ge mechanically stacked under GaAs

    SciTech Connect (OSTI)

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

    1987-10-01T23:59:59.000Z

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

  13. CO{sub 2} laser-based dispersion interferometer utilizing orientation-patterned gallium arsenide for plasma density measurements

    SciTech Connect (OSTI)

    Bamford, D. J.; Cummings, E. A.; Panasenko, D. [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States)] [Physical Sciences Inc., 6652 Owens Drive, Pleasanton, California 94588 (United States); Fenner, D. B.; Hensley, J. M. [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States)] [Physical Sciences Inc., 20 New England Business Center, Andover, Massachusetts 01810 (United States); Boivin, R. L.; Carlstrom, T. N.; Van Zeeland, M. A. [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)] [General Atomics, P.O. Box 85608, San Diego, California 92186 (United States)

    2013-09-15T23:59:59.000Z

    A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma. A simple phase-extraction technique based on combining measurements from two successive pulses of the plasma has been used. The noise-equivalent line density was measured to be 1.7 × 10{sup 17} m{sup ?2} in a detection bandwidth of 950 kHz. One of the orientation-patterned crystals produced 13 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 13 W of peak power. Two crystals arranged sequentially produced 58 mW of peak power at the second-harmonic wavelength from a carbon dioxide laser with 37 W of peak power.

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

    E-Print Network [OSTI]

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

    2009-03-01T23:59:59.000Z

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

  15. E-Print Network 3.0 - activated gaas surface Sample Search Results

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

    Collection: Materials Science 8 Dissimilar and Nanomaterials for Optoelectronic Devices Summary: ) on GaAs Diluted-N-based QW Sb-based QW (GaInNAsSb) QD-based active...

  16. E-Print Network 3.0 - annealed gaas spectroscopic Sample Search...

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

    annealed epitaxial Ge surface. Fig. 2. RHEED patterns during growth of an APD-free GaAs film... was deposited and annealed for 20 min at either 350, 560, or 640C to observe the...

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

    SciTech Connect (OSTI)

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

    2013-12-04T23:59:59.000Z

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

  18. Synthesis, Structures, and Magnetic Properties of Rare-Earth Cobalt Arsenides, RCo2As2 (R = La, Ce, Pr, Nd)

    SciTech Connect (OSTI)

    Thompson, Corey [Florida State University, Tallahassee] [Florida State University, Tallahassee; Tan, Xiaoyan [Florida State University, Tallahassee] [Florida State University, Tallahassee; Kovnir, Kirill [Florida State University, Tallahassee] [Florida State University, Tallahassee; Garlea, Vasile O [ORNL] [ORNL; Shatruk, Michael [Florida State University, Tallahassee] [Florida State University, Tallahassee

    2014-01-01T23:59:59.000Z

    Four rare-earth cobalt arsenides, RCo2As2 (R = La, Ce, Pr, Nd), were obtained by reactions of constituent elements in molten Bi. The use of Bi flux also allowed the growth of representative single crystals. All compounds are isostructural and belong to the ThCr2Si2 structure type (space group I4/mmm). The formation of Co vacancies is observed in all structures, while the structures of La- and Ce-containing compounds also show incorporation of minor Bi defects next to the R crystallographic site. Correspondingly, the general formula of these materials can be written as R1 xBixCo2 As2, with x/ = 0.03/0.1, 0.05/0.15, 0/0.2, and 0/0.3 for R = La, Ce, Pr, and Nd, respectively. All compounds exhibit high-temperature ferromagnetic ordering of Co magnetic moments in the range of 150-200 K. Electronic band structure calculations revealed a high peak in the density of states at the Fermi level, thus supporting the itinerant nature of magnetism in the Co sublattice. The magnetic ordering in the lanthanide sublattice takes place at lower temperatures, with the R moments aligning antiparallel to the Co moments to give a ferrimagnetic ground state. The measurements on oriented single crystals demonstrated significant magnetic anisotropy in the ferrimagnetic state, with the preferred moment alignment along the c axis of the tetragonal lattice. Neutron powder diffraction failed to reveal the structure of magnetically ordered states, but confirmed the presence of Co vacancies. X-ray absorption near-edge structure spectroscopy on Ce1.95Bi0.05Co1.85As2 showed the average oxidation state of Ce to be +3.06. Solid state NMR spectroscopy revealed a substantially reduced hyperfine field on the Co atoms in the vicinity of Bi defects.

  19. Narrow energy band gap gallium arsenide nitride semi-conductors and an ion-cut-synthesis method for producing the same

    DOE Patents [OSTI]

    Weng, Xiaojun; Goldman, Rachel S.

    2006-06-06T23:59:59.000Z

    A method for forming a semi-conductor material is provided that comprises forming a donor substrate constructed of GaAs, providing a receiver substrate, implanting nitrogen into the donor substrate to form an implanted layer comprising GaAs and nitrogen. The implanted layer is bonded to the receiver substrate and annealed to form GaAsN and nitrogen micro-blisters in the implanted layer. The micro-blisters allow the implanted layer to be cleaved from the donor substrate.

  20. Defect studies in low-temperature-grown GaAs

    SciTech Connect (OSTI)

    Bliss, D.E.

    1992-11-01T23:59:59.000Z

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

  1. Defect studies in low-temperature-grown GaAs

    SciTech Connect (OSTI)

    Bliss, D.E.

    1992-11-01T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    Cardozo, Benjamin Lewin

    2004-12-21T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Chen, Zhi

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

  4. Orientation of tectonic stresses in central Kentucky during U. Devonian/L. Mississippian times: Evidence from quartz veins (after gypsum) in NE-trending, systematic joints in shales

    SciTech Connect (OSTI)

    Grover, J.; Dupuis-Nouille, E.M. (Univ. of Cincinnati, Cincinnati, OH (United States). Dept. of Geology)

    1992-01-01T23:59:59.000Z

    Quartz replacing fibrous gypsum and anhydrite pseudomorphically (QAS; quartz after sulfate''), and preserving characteristic crack-seal'' and chickenwire'' textures, occurs in extensional veins at four locations in central KY. The veins occupy a systematic set of NE-SW-trending, vertical joints within the essentially flat-lying shales of the Renfro Member of the Mississippian Borden Formation and the Late Devonian New Albany Shale. The four QAS occurrences discovered to date are located northeast of the Borden Front. At one site in the New Albany Shale, QAS veins show clear evidence of penecontemporaneous deformation. It is proposed that at all QAS locations, gypsum precipitated in incipient joints before complete lithification of the sediment, and grew perpendicular to the fractures to form extensional veins in the soft but firm muds. The orientations of the joints now marked by QAS veins are broadly consistent with regional patterns of NE-SW-trending systematic joints and lineaments in southern IN and in central and eastern KY. These systematic fracture patterns do not correspond directly to known basement faults or rift systems, although they are consistent with modern stress directions in eastern and western KY, measured in situ in wells and by earthquake fault-plane solutions. It is proposed that this systematic trend marks the regional tectonic stress pattern characteristic of southern IN and central and eastern KY at, and since the Late Devonian. The evidence of penecontemporaneous sedimentary deformation in joints of U. Devonian age, marked and preserved by quartz replacement of early gypsum, is sufficient to show that while the systematic NE-trending joint set in KY may also be modern it is not uniquely so.

  5. Evolution of ion-induced nanoparticle arrays on GaAs surfaces

    SciTech Connect (OSTI)

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

    2014-05-05T23:59:59.000Z

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

  6. Second harmonic generation in photonic crystal cavities in (111)-oriented GaAs

    SciTech Connect (OSTI)

    Buckley, Sonia, E-mail: bucklesm@stanford.edu; Radulaski, Marina; Vu?kovi?, Jelena [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States)] [E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305 (United States); Biermann, Klaus [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)] [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

    2013-11-18T23:59:59.000Z

    We demonstrate second harmonic generation at telecommunications wavelengths in photonic crystal cavities in (111)-oriented GaAs. We fabricate 30 photonic crystal structures in both (111)- and (100)-oriented GaAs and observe an increase in generated second harmonic power in the (111) orientation, with the mean power increased by a factor of 3, although there is a large scatter in the measured values. We discuss possible reasons for this increase, in particular, the reduced two photon absorption for transverse electric modes in (111) orientation, as well as a potential increase due to improved mode overlap.

  7. 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)

    2013-12-04T23:59:59.000Z

    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.

  8. 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 Deinegaa and Sajeev Johnab We present designs that enable a significant increase of solar absorption­99.5% solar absorption is demonstrated depending on the photonic crystal architecture used and the nature

  9. 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-frequency electronics3,4 and most forms of optoelectronics5,6 . However, growing large, high quality wafers implementation. More tractable, yet still difficult, problems appear in advanced electronics and optoelectronics

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

    E-Print Network [OSTI]

    MENON, M.; Allen, Roland E.

    1991-01-01T23:59:59.000Z

    on GaAs. H=HO+ V, @11 0 0 0 (2.7) (2.8) The Green's function for this system is G =(el ?H ) (2.9) Let H be the 1V XX Hamiltonian matrix for a large sys- tem (N~ ~ here). We suppose that H differs from an unperturbed Hamiltonian Ho only in some...

  11. SSL/TLS Session-Aware User Authentication Using a GAA Bootstrapped Key

    E-Print Network [OSTI]

    Sheldon, Nathan D.

    SSL/TLS Session-Aware User Authentication Using a GAA Bootstrapped Key Chunhua Chen1 , Chris J.mitchell@rhul.ac.uk Abstract. Most SSL/TLS-based electronic commerce (e-commerce) ap- plications (including Internet banking a server effectively, and because user authentication methods are typi- cally decoupled from SSL

  12. 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

  13. Surface science analysis of GaAs photocathodes following sustained electron beam delivery

    SciTech Connect (OSTI)

    Carlos Hernandez-Garcia, Fay Hannon, Marcy Stutzman, V. Shutthanandan, Z. Zhu, M. Nandasri, S. V. Kuchibhatla, S. Thevuthasan, W. P. Hess

    2012-06-01T23:59:59.000Z

    Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Photocathode quantum efficiency (QE) degradation is due to residual gasses in the electron source vacuum system being ionized and accelerated back to the photocathode. These investigations are a first attempt to characterize the nature of the photocathode degradation, and employ multiple surface and bulk analysis techniques to investigate damage mechanisms including sputtering of the Cs-oxidant surface monolayer, other surface chemistry effects, and ion implantation. Surface and bulk analysis studies were conducted on two GaAs photocathodes, which were removed from the JLab FEL DC photoemission gun after delivering electron beam, and two control samples. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, two high-polarization strained superlattice GaAs photocathode samples, one removed from the Continuous Electron Beam Accelerator Facility (CEBAF) photoinjector and one unused, were also analyzed using Transmission Electron Microscopy (TEM) and SIMS. It was found that heat cleaning the FEL GaAs wafer introduces surface roughness, which seems to be reduced by prolonged use. The bulk GaAs samples retained a fairly well organized crystalline structure after delivering beam but shows evidence of Cs depletion on the surface. Within the precision of the SIMS and RBS measurements the data showed no indication of hydrogen implantation or lattice damage from ion back bombardment in the bulk GaAs wafers. In contrast, SIMS and TEM measurements of the strained superlattice photocathode show clear crystal damage in the wafer from ion back bombardment.

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

    E-Print Network [OSTI]

    Dumitrica, T.; Allen, Roland E.

    2002-01-01T23:59:59.000Z

    We present nonadiabatic simulations of the coherent response of crystalline GaAs irradiated by intense femtosecond-scale laser pulses. Above a threshold fluence, which corresponds to promotion of about 12% of the valence electrons...

  15. Nanometer-scale GaAs clusters from organometallic precursors Peter C. Sercel, Winston A. Saunders, Harry A. Atwater,

    E-Print Network [OSTI]

    Atwater, Harry

    the first direct observation of gas-phase ho- mogeneous nucleation of GaAs by the thermophoretic col thermophoret- ically on a holey carbon film which is mounted on a stain- less steel fixture aligned coaxially

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

    E-Print Network [OSTI]

    Choi, Kyoo Nam

    1989-01-01T23:59:59.000Z

    FABRICATION OF WIDEBAND OPTOELECTRONIC DIFFERENTIAL AMPLIFIER USING A BALANCED RECEIVER ON A SEMI-INSULATING GAAS SUBSTRATE A Thesis by KYOO NAM CHOI Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 1989 Major Subject: Electrical Engineering FABRICATION Ol' WIDEBAND OPTOELECTRONIC DIFFERENTIAL A1VIPLIFIER USING A BAI, ANCED RECEIVER ON A SEMI. INSULATING GAAS SUBSTRATE A Thesis by l(YOO NAM...

  17. A near-infrared photoluminescence study of GaAs nanocrystals in SiO2 films formed by sequential ion implantation

    E-Print Network [OSTI]

    Atwater, Harry

    A near-infrared photoluminescence study of GaAs nanocrystals in SiO2 films formed by sequential ion GaAs nanocrystals are formed in SiO2 films and several PL bands appear in the red and near-infrared spectral region. Defects and impurities in GaAs nanocrystals and SiO2 cause weak luminescence in the near-infrared

  18. Effects of atomic hydrogen and deuterium exposure on high polarization GaAs photocathodes

    SciTech Connect (OSTI)

    M. Baylac; P. Adderley; J. Brittian; J. Clark; T. Day; J. Grames; J. Hansknecht; M. Poelker; M. Stutzman; A. T. Wu; A. S. Terekhov

    2005-12-01T23:59:59.000Z

    Strained-layer GaAs and strained-superlattice GaAs photocathodes are used at Jefferson Laboratory to create high average current beams of highly spin-polarized electrons. High electron yield, or quantum efficiency (QE), is obtained only when the photocathode surface is atomically clean. For years, exposure to atomic hydrogen or deuterium has been the photocathode cleaning technique employed at Jefferson Laboratory. This work demonstrates that atomic hydrogen cleaning is not necessary when precautions are taken to ensure that clean photocathode material from the vendor is not inadvertently dirtied while samples are prepared for installation inside photoemission guns. Moreover, this work demonstrates that QE and beam polarization can be significantly reduced when clean high-polarization photocathode material is exposed to atomic hydrogen from an rf dissociator-style atomic hydrogen source. Surface analysis provides some insight into the mechanisms that degrade QE and polarization due to atomic hydrogen cleaning.

  19. 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)

    2013-11-04T23:59:59.000Z

    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.

  20. Cavity nucleation and evolution in He-implanted Si and GaAs

    SciTech Connect (OSTI)

    Follstaedt, D.M.; Myers, S.M.; Petersen, G.A.; Barbour, J.C.

    1995-12-01T23:59:59.000Z

    The criteria for forming stable cavities by He{sup +} implantation and annealing are examined for Si and GaAs. In Si, implanting at room temperature requires a minimum of 1.6 at. % He to form a continuous layer of cavities after annealing at 700{degrees}C. The cavities are located at dislocations and planar defects. Implanting peak He concentrations just above this threshold produces narrow layers of cavities at the projected range. In GaAs, room-temperature implantation followed by annealing results in exfoliation of the surface layer. Cavities were formed instead by implanting Ar followed by overlapping He, both at 400{degrees}C, with additional annealing at 400{degrees}C to outgas the He. This method forms 1.5--3.5 nm cavities that are often on [111] planar defects.

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

    SciTech Connect (OSTI)

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

    2014-09-21T23:59:59.000Z

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

  2. 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)

    2014-01-27T23:59:59.000Z

    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.

  3. Design and realization of a GaAs FET integrated with a heterojunction photodiode

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1595 Design and realization of a GaAs FET integrated with a heterojunction photodiode F. Therez, M, accepté le 6 juillet 1987) Résumé. 2014 L'association d'une photodiode à hétérojonction et d'un circuit circuits intégrant l'amplificateur et la photodiode. Les divers dispositifs sont caractérisés et analysés

  4. 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 [Physics Department, Centro de Investigacion y de Estudios Avanzados del IPN, Apartado Postal 14-740, Mexico D.F., 07000 (Mexico); Pulzara Mora, Alvaro [Universidad Nacional de Colombia - Sede Manizales, A. A. 127 (Colombia); Mendez Garcia, Victor H. [Instituto de Investigacion en Comunicacion Optica, Universidad Autonoma de San Luis Potosi, Av. Karakorum 1470, Lomas 4a Seccion, C.P. 78210, San Luis Potosi (Mexico)

    2007-02-09T23:59:59.000Z

    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.

  5. Identification of As-vacancy complexes in Zn-diffused GaAs

    SciTech Connect (OSTI)

    Elsayed, M. [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Department of Physics, Faculty of Science, Minia University, 61519 Minia (Egypt); Krause-Rehberg, R. [Department of Physics, Martin Luther University Halle, 06099 Halle (Germany); Korff, B. [Bremen Center for Computational Materials Science, University Bremen, 28359 Bremen (Germany); Richter, S. [Fraunhofer Center for Silicon Photovoltaics CSP, 06120 Halle (Saale) (Germany); Leipner, H. S. [Center of Materials Science, Martin Luther University Halle, 06099 Halle (Germany)

    2013-03-07T23:59:59.000Z

    We have used positron annihilation spectroscopy to study the introduction of point defects in Zn-diffused semi-insulating GaAs. The diffusion was performed by annealing the samples for 2 h at 950 Degree-Sign C. The samples were etched in steps of 7 {mu}m. Both Doppler broadening using slow positron beam and lifetime spectroscopy studies were performed after each etching step. Both techniques showed the existence of vacancy-type defects in a layer of about 45 {mu}m. Secondary ion mass spectroscopy measurements illustrated the presence of Zn at high level in the sample almost up to the same depth. Vacancy-like defects as well as shallow positron traps were observed by lifetime measurements. We distinguish two kinds of defects: As vacancy belongs to defect complex, bound to most likely one Zn atom incorporated on Ga sublattice, and negative-ion-type positron traps. Zn acceptors explained the observation of shallow traps. The effect of Zn was evidenced by probing GaAs samples annealed under similar conditions but without Zn treatment. A defect-free bulk lifetime value is detected in this sample. Moreover, our positron annihilation spectroscopy measurements demonstrate that Zn diffusion in GaAs system is governed by kick-out mechanism.

  6. Gallium arsenide-based ternary compounds and multi-band-gap solar cell research. Annual subcontract report, 15 April 1988--14 June 1990

    SciTech Connect (OSTI)

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

    1993-02-01T23:59:59.000Z

    Aim of this contract is the achievement of a high-efficiency, low-cost solar cell. The basic approach to the problem is centered upon the heteroepitaxial growth of a III-V compound material onto a single-crystal silicon wafer. The growth technique employed is metalorganic chemical vapor deposition. The silicon wafer may serve as a mechanical substrate and ohmic contact for a single-junction device, or may contain a p-n junction of its own and form the bottom cell of a two junction tandem solar cell structure. The III-V material for the single-junction case is GaAs and for the two-junction case is either GaAlAs or GaAsP, either material having the proper composition to yield a band gap of approximately 1.7 eV. Results achieved in this contract include the following: (1) a 17.6% efficient GaAs-on-Si solar cell; (2) an 18.5% efficient GaAs-on-Si concentrator solar cell at 400 suns; (3) a 24.8% efficient GaAs-on-GaAs solar cell; (4) a 28.7% efficient GaAs-on-GaAs concentrator solar cell at 200 suns; (5) measurement of the effects of dislocation density and emitter doping on GaAs cells; and (6) improvements in the growth process to achieve reproducible thin AlGaAs window layers with low recombination velocities and environmental stability.

  7. Final report on LDRD project 105967 : exploring the increase in GaAs photodiode responsivity with increased neutron fluence.

    SciTech Connect (OSTI)

    Blansett, Ethan L.; Geib, Kent Martin; Cich, Michael Joseph; Wrobel, Theodore Frank; Peake, Gregory Merwin; Fleming, Robert M.; Serkland, Darwin Keith; Wrobel, Diana L.

    2008-01-01T23:59:59.000Z

    A previous LDRD studying radiation hardened optoelectronic components for space-based applications led to the result that increased neutron irradiation from a fast-burst reactor caused increased responsivity in GaAs photodiodes up to a total fluence of 4.4 x 10{sup 13} neutrons/cm{sup 2} (1 MeV Eq., Si). The silicon photodiodes experienced significant degradation. Scientific literature shows that neutrons can both cause defects as well as potentially remove defects in an annealing-like process in GaAs. Though there has been some modeling that suggests how fabrication and radiation-induced defects can migrate to surfaces and interfaces in GaAs and lead to an ordering effect, it is important to consider how these processes affect the performance of devices, such as the basic GaAs p-i-n photodiode. In this LDRD, we manufactured GaAs photodiodes at the MESA facility, irradiated them with electrons and neutrons at the White Sands Missile Range Linac and Fast Burst Reactor, and performed measurements to show the effect of irradiation on dark current, responsivity and high-speed bandwidth.

  8. Direct determination of exact charge states of surface point defects using scanning tunneling microscopy: As vacancies on GaAs ,,110...

    E-Print Network [OSTI]

    microscopy: As vacancies on GaAs ,,110... Kuo-Jen Chao, Arthur R. Smith, and Chih-Kang Shih* Department of the charge state of surface As vacancies on p-type GaAs 110 using scanning tunneling microscopy. This method utilizes the compensation between the local band bending result- ing from the As vacancy and the p

  9. Preparation of silicon substrates for gallium-arsenide solar cells by electron-beam-pulse processing. Annual technical report, March 15, 1980-March 15, 1981

    SciTech Connect (OSTI)

    Tobin, S.P.

    1981-05-01T23:59:59.000Z

    In the past year a process has been developed for creating high-quality epitaxial layers of germanium on silicon substrates using rapid heating and cooling with a pulsed electron beam. This single-crystal germanium coating is the key to the production of high efficiency GaAs solar cells on low-cost silicon substrates in an economical manner. Thin (less than or equal to 1 ..mu..m) layers of Ge have been deposited on Si wafers by chemical vapor deposition (CVD) in single-crystal form or by vacuum evaporation in amorphous or polycrystalline form. The CVD films have given the best results, with good crystallinity and electrical properties as deposited. A persistent problem with surface roughness in the as-deposited films has been overcome by pulsed electron beam melting of the near-surface region in time periods on the order of a microsecond. The brief molten period smooths the surface features without compromising the crystallinity, electrical properties, or interfacial abruptness of the Ge film. These layers are of a quality suitable for further evaluation by GaAs growth and cell processing in the next phase of the program. Pulsed electron beam processing also serves a vital function for the evaporated Ge films, which are melted by the beam and recrystallized on the Si substrates, epitaxial single crystal Ge layers result from amorphous or polycrystalline starting films. To date results have not been as satisfactory as for CVD films; contamination from several sources has been identified as a problem. Many of these sources have been eliminated, so that a decision on the intrinsic limitations of the evaporated film approach should be made in the near future.

  10. Gallium arsenide-based ternary compounds and multi-band-gap solar cell research. Final subcontract report, 1 April 1988--31 March 1990

    SciTech Connect (OSTI)

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

    1993-07-01T23:59:59.000Z

    This report describes work to achieve a high-efficiency, low-cost solar cell. The basic approach to the problem is centered upon the heteroepitaxial growth of a III-V compound material onto a single-crystal silicon wafer. The growth technique employed throughout this work is metal-organic chemical vapor deposition. The silicon wafer may serve as a mechanical substrate and ohmic contact for a single-junction device, or it may contain a p-n junction of its own and form the bottom cell of a two-junction tandem solar cell structure. The III-V material for the single-junction case is GaAs, and for the two-junction case it is either GaAlAs or GaAsP, either material having the proper composition to yield a band gap of approximately 1.7 eV. Results achieved in this contract include (1) a 17.6%-efficient GaAs-on-Si solar cell; (2) an 18.5%-efficient GaAs-on-Si concentrator solar cell at 400 suns; (3) a 24.8%-efficient GaAs-on-GaAs solar cell; (4) a 28.7%-efficient GaAs-on-GaAs concentrator solar cell at 200 suns; (5) the measurement of the effects of dislocation density and emitter doping on GaAs cells; and (6) improvements in the growth process to achieve reproducible thin AlGaAs window layers with low recombination velocities and environmental stability.

  11. GaAs single quantum dot embedded into AlGaAs nanowire

    SciTech Connect (OSTI)

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

    2013-12-04T23:59:59.000Z

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

  12. Nucleation and Growth of GaN on GaAs (001) Substrates

    SciTech Connect (OSTI)

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

    1999-05-03T23:59:59.000Z

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

  13. Picosecond buildup and relaxation of intense stimulated emission in GaAs

    SciTech Connect (OSTI)

    Ageeva, N. N.; Bronevoi, I. L., E-mail: bil@cplire.ru; Zabegaev, D. N.; Krivonosov, A. N. [Russian Academy of Sciences, Kotelnikov Institute of Radio Engineering and Electronics (Russian Federation)

    2013-04-15T23:59:59.000Z

    In support of the idea developed previously based on circumstantial evidence, we have found that stimulated emission emerges in GaAs and its intensity increases with a picosecond delay relative to the front of powerful picosecond optical pumping that produced a dense electron-hole plasma. The emission intensity relaxes with decreasing pumping with a characteristic time of {approx}10 ps. We have derived the dependences of the delay time, the relaxation time, and the duration of the picosecond emission pulse on its photon energy. The estimates based on the fact that the relaxation of emission is determined by electron-hole plasma cooling correspond to the measured relaxation time.

  14. Back-contacted and small form factor GaAs solar cell.

    SciTech Connect (OSTI)

    Clews, Peggy Jane; Wanlass, Mark W. (National Renewable Energy Laboratory, Golden, CO); Sanchez, Carlos A.; Pluym, Tammy; Cruz-Campa, Jose Luis; Okandan, Murat; Gupta, Vipin P.; Nielson, Gregory N.; Resnick, Paul James

    2010-07-01T23:59:59.000Z

    We present a newly developed microsystem enabled, back-contacted, shade-free GaAs solar cell. Using microsystem tools, we created sturdy 3 {micro}m thick devices with lateral dimensions of 250 {micro}m, 500 {micro}m, 1 mm, and 2 mm. The fabrication procedure and the results of characterization tests are discussed. The highest efficiency cell had a lateral size of 500 {micro}m and a conversion efficiency of 10%, open circuit voltage of 0.9 V and a current density of 14.9 mA/cm{sup 2} under one-sun illumination.

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

    SciTech Connect (OSTI)

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

    2013-08-12T23:59:59.000Z

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

  16. Ultrafast magneto-photocurrents in GaAs: Separation of surface and bulk contributions

    E-Print Network [OSTI]

    Schmidt, Christian B; Tarasenko, Sergey A; Bieler, Mark

    2015-01-01T23:59:59.000Z

    We induce ultrafast magneto-photocurrents in a GaAs crystal employing interband excitation with femtosecond laser pulses at room temperature and non-invasively separate surface and bulk contributions to the overall current response. The separation between the different symmetry contributions is achieved by measuring the simultaneously emitted terahertz radiation for different sample orientations. Excitation intensity and photon energy dependences of the magneto-photocurrents for linearly and circularly polarized excitations reveal an involvement of different microscopic origins, one of which we believe is the inverse Spin-Hall effect. Our experiments are important for a better understanding of the complex momentum-space carrier dynamics in magnetic fields.

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

    SciTech Connect (OSTI)

    Aleshkin, V. Ya. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Afonenko, A. A. [Belarussian State University (Belarus)] [Belarussian State University (Belarus); Dikareva, N. V. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation); Dubinov, A. A., E-mail: sanya@ipm.sci-nnov.ru; Kudryavtsev, K. E.; Morozov, S. V. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation)] [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Nekorkin, S. M. [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)] [Research Physical-Technical Institute of Nizhni Novgorod State University (Russian Federation)

    2013-11-15T23:59:59.000Z

    The waveguide effect of GaAsSb quantum wells in a semiconductor-laser structure based on GaAs is studied theoretically and experimentally. It is shown that quantum wells themselves can be used as waveguide layers in the laser structure. As the excitation-power density attains a value of 2 kW/cm{sup 2} at liquid-nitrogen temperature, superluminescence at the wavelength corresponding to the optical transition in bulk GaAs (at 835 nm) is observed.

  18. A Single Layer of Mn in a GaAs Quantum Well: A Ferromagnet with Quantum Fluctuations

    SciTech Connect (OSTI)

    Melko, Roger G [ORNL; Fishman, Randy Scott [ORNL; Reboredo, Fernando A [ORNL

    2007-01-01T23:59:59.000Z

    Some of the highest transition temperatures achieved for Mn-doped GaAs have been in &-doped heterostructures with well-separated planes of Mn. But in the absense of magnetic anisotropy, the Mermin-Wagner theorem implies that a single plane of magnetic ions cannot be ferromagnetic. We show that the same mechanism that produces magnetic frustration and suppresses the transition can stabilize ferromagnetic order for a single layer of Mn in a GaAs quantum well. But this comes at the price of quantum fluctuations that suppress the ordered moment from that of a fully saturated ferromagnet.

  19. Bistability of self-modulation of the GaAs intrinsic stimulated picosecond radiation spectrum

    SciTech Connect (OSTI)

    Ageeva, N. N.; Bronevoi, I. L., E-mail: bil@cplire.ru; Zabegaev, D. N.; Krivonosov, A. N. [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)] [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)

    2013-08-15T23:59:59.000Z

    The bistability of self-modulation of the spectrum of the stimulated picosecond radiation that appears during picosecond optical pumping of GaAs is detected. The radiation is measured before it reaches the end faces of a sample. One set of equidistant modes occurs in the radiation spectrum at the radiation pulse front. A set of modes located at the center between the initial modes replaces the first set in the descending radiation branch. The intermode interval inside each set coincides with the calculated interval between the eigenmodes of the GaAs layer, which is an active cavity. The radiation rise time turns out to be an oscillating function of the photon energy. The spectrum evolution is self-consistent so that the time-integrated spectrum and the spectrum-integrated radiation pulse envelope have a smooth (without local singularities) shape. The revealed bistability explains the physical nature of the two radiation-induced states of population depletion between which subterahertz self-oscillations in the radiation field were detected earlier. The radiation spectrum self-modulation is assumed to be a variant of stimulated Raman scattering.

  20. Surface Science Analysis of GaAs Photocathodes Following Sustained Electron Beam Delivery

    SciTech Connect (OSTI)

    Shutthanandan, V.; Zhu, Zihua; Stutzman, Marcy L.; Hannon, Fay; Hernandez-Garcia, Carlos; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Thevuthasan, Suntharampillai; Hess, Wayne P.

    2012-06-12T23:59:59.000Z

    Degradation of the photocathode materials employed in photoinjectors represents a challenge for sustained operation of nuclear physics accelerators and high power Free Electron Lasers (FEL). Several photocathode degradation processes are suspected, including defect formation by ion back bombardment, photochemistry of surface adsorbed species and irradiation-induced surface defect formation. To better understand the mechanisms of photocathode degradation, we have conducted surface and bulk analysis studies of two GaAs photocathodes removed from the FEL photoinjector after delivering electron beam for a few years. The analysis techniques include Helium Ion Microscopy (HIM), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Secondary Ion Mass Spectrometry (SIMS). In addition, strained super-lattice GaAs photocathode samples, removed from the CEBAF photoinjector were analyzed using Transmission Electron Microscopy (TEM) and SIMS. This analysis of photocathode degradation during nominal photoinjector operating conditions represents first steps towards developing robust new photocathode designs necessary for generating sub-micron emittance electron beams required for both fourth generation light sources and intense polarized CW electron beams for nuclear and high energy physics facilities.

  1. 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 been known that non-single- crystals films can be used for solar cells as, for example, in the selenium and copper oxide photo- electric exposnre meter. More recently [1], the cadmium sulfide film-type solar cell

  2. All-optical generation and detection of subpicosecond ac spin-current pulses in GaAs

    E-Print Network [OSTI]

    Ruzicka, Brian Andrew; Higley, Karl; Werake, Lalani Kumari; Zhao, Hui

    2008-07-01T23:59:59.000Z

    Subpicosecond ac spin-current pulses are generated optically in GaAs bulk and quantum wells at room temperature and at 90 K through quantum interference between one-photon and two-photon absorptions driven by two phase-locked ...

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

    E-Print Network [OSTI]

    Khare, Sanjay V.

    Diffusion of a Ga adatom on the GaAs(001)c(4×4)heterodimer surface: A first principles study J Diffusion barriers Reconstruction Density functional calculations The adsorption and diffusion behavior functional theory (DFT) computations in the local density approxima- tion. Structural and bonding features

  4. 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

    2007-09-07T23:59:59.000Z

    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

  5. X-ray imaging and diffraction from surface phonons on GaAs W. Sauer,a)

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    , the driver frequency of the synchrotron was multiplied 102 times by a phase-locked loop PLL , ampli- fied are excited on the GaAs 001 surface by using interdigital transducers, designed for frequencies of up to 900 to measured diffraction profiles at different excitation voltages, the SAW amplitudes were calculated

  6. Femtosecond-scale response of GaAs to ultrafast laser pulses Traian Dumitrica* and Roland E. Allen

    E-Print Network [OSTI]

    Allen, Roland E.

    Femtosecond-scale response of GaAs to ultrafast laser pulses Traian Dumitrica* and Roland E. Allen ordinary heating of the sample by phonon emission, there is convinc- ing evidence that ultrafast pulses of the initial stages of the interaction of a laser pulse with a semiconductor, which show that ultrafast disor

  7. Large-Signal HBT Model with Improved Collector Transit Time Formulation for GaAs and InP Technologies

    E-Print Network [OSTI]

    Asbeck, Peter M.

    mi': iaE Large-Signal HBT Model with Improved Collector Transit Time Formulation for GaAs and In large-signal HBT model which accurately accounts for the intricate hias dependence of collector delay collector delay function accounts for the variation of electron velocity with electric field

  8. Near-infrared sideband generation induced by intense far-infrared radiation in GaAs quantum wells

    E-Print Network [OSTI]

    Kono, Junichiro

    Near-infrared sideband generation induced by intense far-infrared radiation in GaAs quantum wells J illuminated with near-infrared NIR radiation at frequency nir and intense far-infrared FIR radiation from and quenching of photoluminescence PL .8,9 The nonlinear interaction of FIR and near-infrared NIR radiation

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

    E-Print Network [OSTI]

    Lee, Kenneth Eng Kian

    2009-01-01T23:59:59.000Z

    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 > ...

  10. Energy distribution of nonequilibrium electrons and optical phonons in GaAs under band-to-band pumping by intense short pulses of light

    SciTech Connect (OSTI)

    Altybaev, G. S.; Kumekov, S. E., E-mail: skumekov@mail.ru; Mahmudov, A. A. [Satpaev Kazakh National Technical University (Kazakhstan)

    2009-03-15T23:59:59.000Z

    Deviation from the Fermi distribution of nonequilibrium electrons and distribution of 'hot' optical phonons in GaAs under band-to-band pumping by picosecond pulses of light are calculated.

  11. 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., E-mail: ib.hendra@gmail.com; Rahayu, F., E-mail: ib.hendra@gmail.com; Darma, Y., E-mail: ib.hendra@gmail.com [Physical Vapor Deposition Laboratory, Physics of Material Electronics Research, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

    2014-03-24T23:59:59.000Z

    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.

  12. Photoluminescence of GaAs films grown by vacuum chemical epitaxy

    SciTech Connect (OSTI)

    Bernussi, A.A.; Barreto, C.L.; Carvalho, M.M.G.; Motisuke, P.

    1988-08-01T23:59:59.000Z

    GaAs layers grown by vacuum chemical epitaxy (VCE) are investigated by low-temperature photoluminescence. A qualitative relation between the growth parameters and the shallow-impurity-incorporation mechanism is established. It was observed that the predominant shallow acceptor is carbon, and its incorporation during the growth process decreases with the As:Ga ratio, increases with growth temperature until 750 /sup 0/C, and then it diminishes. In this work we compare the characteristics observed in the VCE system with those in conventional molecular-beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). Our results show that this system contains some advantages from both the MBE and MOCVD systems. The photoluminescence spectra also show that at low As:Ga ratios the generation of As vacancies or its complexes is strongly enhanced.

  13. Measurement of electron beam polarization from unstrained GaAs via two-photon photoemission

    SciTech Connect (OSTI)

    McCarter, James L. [Univ. of Virginia, Charlottesville, VA (United States); Afanasev, A. [George Washington Univ., Washingon, DC (United States); Gay, T. J. [Univ. of Nebraska, Lincoln, NE (United States); Hansknecht, John C. [JLAB, Newport News, VA (United States); Kechiantz, A. [George Washington Univ., Washingon, DC (United States); Poelker, B. Matthew [JLAB, Newport News, VA (United States)

    2014-02-01T23:59:59.000Z

    Two-photon absorption of 1560 nm light was used to generate polarized electron beams from unstrained GaAs photocathodes of varying thickness: 625 {mu}m, 0.32 {mu}m, and 0.18 {mu}m. For each photocathode, the degree of spin polarization of the photoemitted beam was less than 50%, contradicting earlier predictions based on simple quantum mechanical selection rules for spherically-symmetric systems but consistent with the more sophisticated model of Bhat et al. (Phys. Rev. B 71 (2005) 035209). Polarization via two-photon absorption was the highest from the thinnest photocathode sample and comparable to that obtained via one-photon absorption (using 778 nm light), with values 40.3 +- 1.0% and 42.6 +- 1.0%, respectively.

  14. Molecular-beam epitaxial growth of boron-doped GaAs films

    SciTech Connect (OSTI)

    Hoke, W.E.; Lemonias, P.J.; Weir, D.G. [Raytheon Research Division, Lexington, MA (United States)] [and others] [Raytheon Research Division, Lexington, MA (United States); and others

    1993-05-01T23:59:59.000Z

    GaAs films doped with boron in the 10{sup 20} cm{sup {minus}3} range were grown by solid source molecular-beam epitaxy. Lattice contractions were observed in x-ray double crystal spectra. Substitutional boron concentrations up to 1.7x10{sup 20} cm{sup {minus}3} were obtained with narrow x-ray linewidths and specular surface morphology. For a given boron flux, the substitutional concentration was dependent on growth temperature. P-type conductivity due to boron incorporation was measured in the films with hole concentration reaching 1x10{sup 19} cm{sup {minus}3}. The lattice contractions exhibited good thermal stability for rapid thermal anneals. 10 refs., 3 figs., 2 tabs.

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

    SciTech Connect (OSTI)

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

    2014-03-01T23:59:59.000Z

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

  16. 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., E-mail: smhsps@rit.edu [Rochester Institute of Technology, Rochester, New York 14623 (United States); Rao Tatavarti, Sudersena; Wibowo, Andree; Pan, Noren; Chern, Kevin [MicroLink Devices, Inc., Niles, Illinois 60714 (United States)] [MicroLink Devices, Inc., Niles, Illinois 60714 (United States); Phillip Ahrenkiel, S. [South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States)] [South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States)

    2013-11-18T23:59:59.000Z

    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}.

  17. Fano Resonance in GaAs 2D Photonic Crystal Nanocavities

    SciTech Connect (OSTI)

    Valentim, P. T.; Guimaraes, P.S. S. [Departamento de Fisica, Universidade Federal de Minas Gerais, Belo Horizonte (Brazil); Instituto Nacional de Ciencia e Tecnologia de Nanodispositivos Semicondutores - INCT-DISSE (Brazil); Luxmoore, I. J.; Szymanski, D.; Whittaker, D. M.; Fox, A. M.; Skolnick, M. S. [Department of Physics and Astronomy, University of Sheffield, Sheffield (United Kingdom); Vasco, J. P. [Instituto de Fisica, Universidad de Antioquia, Medellin (Colombia); Vinck-Posada, H. [Departamento de Fisica, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota (Colombia)

    2011-12-23T23:59:59.000Z

    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.

  18. Open-tube method for diffusion of zinc into GaAs

    SciTech Connect (OSTI)

    Field, R.J.; Ghandhi, S.K.

    1982-07-01T23:59:59.000Z

    Highly reproducible zinc diffusions from 0.03 to 1.5 /mu/m have been made into GaAs using a CVD zinc-doped silica source capped with phosphosilicate glass. This structure permitted the use of an open-tube, flowing inert gas diffusion system. Diffusions were made from 400/degree/ to 700/degree/C, with surface hole concentrations from 0.1 to 1.0*10/sup 20/ cm/sup -3/, and junction depths from 300A to 1.5 /mu/m. The diffusion coefficient and the hole concentration obtained by this technique are very close to those obtained by sealed ampul techniques using a Zn/sub 3/A/sub 2/ source. However, this open-tube system is more convenient to use, and gives highly reproducible results. 13 refs.

  19. Tailoring broadband light trapping of GaAs and Si substrates by self-organised nanopatterning

    SciTech Connect (OSTI)

    Martella, C.; Chiappe, D.; Mennucci, C.; Buatier de Mongeot, F. [Dipartimento di Fisica, Università di Genova, via Dodecaneso 33, I-16146 Genova (Italy)

    2014-05-21T23:59:59.000Z

    We report on the formation of high aspect ratio anisotropic nanopatterns on crystalline GaAs (100) and Si (100) substrates exploiting defocused Ion Beam Sputtering assisted by a sacrificial self-organised Au stencil mask. The tailored optical properties of the substrates are characterised in terms of total reflectivity and haze by means of integrating sphere measurements as a function of the morphological modification at increasing ion fluence. Refractive index grading from sub-wavelength surface features induces polarisation dependent anti-reflection behaviour in the visible-near infrared (VIS-NIR) range, while light scattering at off-specular angles from larger structures leads to very high values of the haze functions in reflection. The results, obtained for an important class of technologically relevant materials, are appealing in view of photovoltaic and photonic applications aiming at photon harvesting in ultrathin crystalline solar cells.

  20. Intermediate-band material based on GaAs quantum rings for solar cells

    SciTech Connect (OSTI)

    Wu Jiang; Shao Dali [Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Li Zhenhua; Kunets, Vasyl P.; Wang Zhiming; Salamo, G. J. [Institute of Nanoscale Materials Science and Engineering, Fayetteville, Arkansas 72701 (United States); Manasreh, M. O. [Department of Electrical Engineering, University of Arkansas, Fayetteville, Arkansas 72701 (United States); Institute of Nanoscale Materials Science and Engineering, Fayetteville, Arkansas 72701 (United States)

    2009-08-17T23:59:59.000Z

    The intermediate-band concept is invoked to explain the photoresponse spectra obtained for unbiased devices fabricated from GaAs quantum rings grown by a droplet epitaxy technique on lattice-matched Al{sub 0.3}Ga{sub 0.7}As barriers. The photoresponse spectra where measured at room temperature in the visible-near-infrared spectral range. The presence of the intermediate band in the device active region is confirmed by measuring the mid-infrared photoresponse, which is attributed to the intersubband transitions in the conduction band. The photocurrent was measured at room temperature and found to be about four orders of magnitude larger than the dark current in the voltage range of {+-} 4.0 V.

  1. Charge tuning in [111] grown GaAs droplet quantum dots

    SciTech Connect (OSTI)

    Bouet, L.; Vidal, M.; Marie, X.; Amand, T.; Wang, G.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Université de Toulouse, 135 Ave. Rangueil, 31077 Toulouse (France); Mano, T.; Ha, N.; Kuroda, T.; Sakoda, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Durnev, M. V.; Glazov, M. M.; Ivchenko, E. L. [Ioffe Physical-Technical Institute RAS, 194021 St.-Petersburg (Russian Federation)

    2014-08-25T23:59:59.000Z

    We demonstrate charge tuning in strain free GaAs/AlGaAs quantum dots (QDs) grown by droplet epitaxy on a GaAs(111)A substrate. Application of a bias voltage allows the controlled charging of the QDs from ?3|e| to +2|e|. The resulting changes in QD emission energy and exciton fine-structure are recorded in micro-photoluminescence experiments at T?=?4?K. We uncover the existence of excited valence and conduction states, in addition to the s-shell-like ground state. We record a second series of emission lines about 25?meV above the charged exciton emission coming from excited charged excitons. For these excited interband transitions, a negative diamagnetic shift of large amplitude is uncovered in longitudinal magnetic fields.

  2. Piezoelectric surface acoustical phonon amplification in graphene on a GaAs substrate

    SciTech Connect (OSTI)

    Nunes, O. A. C., E-mail: oacn@unb.br [Institute of Physics, University of Brasilia, Brasilia, 70910-900 DF (Brazil)

    2014-06-21T23:59:59.000Z

    We study the interaction of Dirac Fermions in monolayer graphene on a GaAs substrate in an applied electric field by the combined action of the extrinsic potential of piezoelectric surface acoustical phonons of GaAs (piezoelectric acoustical (PA)) and of the intrinsic deformation potential of acoustical phonons in graphene (deformation acoustical (DA)). We find that provided the dc field exceeds a threshold value, emission of piezoelectric (PA) and deformation (DA) acoustical phonons can be obtained in a wide frequency range up to terahertz at low and high temperatures. We found that the phonon amplification rate R{sup PA,DA} scales with T{sub BG}{sup S?1} (S=PA,DA), T{sub BG}{sup S} being the Block?Gru{sup ¨}neisen temperature. In the high-T Block?Gru{sup ¨}neisen regime, extrinsic PA phonon scattering is suppressed by intrinsic DA phonon scattering, where the ratio R{sup PA}/R{sup DA} scales with ?1/?(n), n being the carrier concentration. We found that only for carrier concentration n?10{sup 10}cm{sup ?2}, R{sup PA}/R{sup DA}>1. In the low-T Block?Gru{sup ¨}neisen regime, and for n=10{sup 10}cm{sup ?2}, the ratio R{sup PA}/R{sup DA} scales with T{sub BG}{sup DA}/T{sub BG}{sup PA}?7.5 and R{sup PA}/R{sup DA}>1. In this regime, PA phonon dominates the electron scattering and R{sup PA}/R{sup DA}<1 otherwise. This study is relevant to the exploration of the acoustic properties of graphene and to the application of graphene as an acoustical phonon amplifier and a frequency-tunable acoustical phonon device.

  3. EL2-related studies in irradiated and implanted GaAs Laboratoire de Physique de la Matire (associ au CNRS), Institut National des Sciences Appliques de Lyon,

    E-Print Network [OSTI]

    Boyer, Edmond

    donneur profond EL2 est un défaut très important par le rôle qu'il joue dans la compensation du matériau in the compensation of undoped semi-insulating GaAs. The knowledge of the exact EL2 structure becomes of even greater semi-insulating (SI) GaAs uses the liquid- encapsulated Czochralski process with the As vapor pressure

  4. Microstructure characterization of Cu,Ge/n-type GaAs ohmic contacts M. 0. Aboelfotoh, S. Oktyabrsky, and J. Narayan

    E-Print Network [OSTI]

    Woodall, Jerry M.

    contacts of Ge/Pd/n-type GaAs have been proposed.4 This contact scheme involves the deposition of a metal at 325 "C for 30 min, the entire layer of Pd is consumed in the formation of a palladium germanide layer to the Ge/Pd contacts,' and that n-channel GaAs metal- semiconductor field-effect transistors using the q

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

    SciTech Connect (OSTI)

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

    2014-09-08T23:59:59.000Z

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

  6. Influence of uniaxial pressure on the critical temperature for long delays in GaAs junction lasers

    SciTech Connect (OSTI)

    Morosini, M.B.Z.; Patel, N.B.; Nunes, F.D.

    1980-09-01T23:59:59.000Z

    In this work we report on the influence of uniaxial pressure applied perpendicularly to junction laser on the behavior of the critical temperature for the onset of long delays in GaAs junction lasers. Experimental data showing this influence for lasers operating in a TE or TM polarization are presented and explained on the basis of a thermal theory of long delays and related phenomena.

  7. COMPARATIVE STUDY OF CdTe AND GaAs PHOTOREFRACTIVE PERFORMANCES FROM 1m TO 1.55m

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 COMPARATIVE STUDY OF CdTe AND GaAs PHOTOREFRACTIVE PERFORMANCES FROM 1µm TO 1.55µm L.A. de CdTe at different wavelengths from 1.06µm to 1.55µm. The sensitivity and performances of different for the extension of the photorefractive effect towards the wavelength region of 1.3-1.5µm. CdTe appears

  8. Atomic-scale observation of parallel development of super elasticity and reversible plasticity in GaAs nanowires

    SciTech Connect (OSTI)

    Bao, Peite; Du, Sichao; Zheng, Rongkun, E-mail: rongkun.zheng@sydney.edu.au [School of Physics, The University of Sydney, Sydney, NSW 2006 (Australia); Wang, Yanbo; Liao, Xiaozhou, E-mail: xiaozhou.liao@sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Cui, Xiangyuan; Yen, Hung-Wei; Kong Yeoh, Wai; Ringer, Simon P. [School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); Gao, Qiang; Hoe Tan, H.; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia); Liu, Hongwei [Australian Centre for Microscopy and Microanalysis, The University of Sydney, Sydney, NSW 2006 (Australia); Zou, Jin [Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, QLD 4072 (Australia)

    2014-01-13T23:59:59.000Z

    We report the atomic-scale observation of parallel development of super elasticity and reversible dislocation-based plasticity from an early stage of bending deformation until fracture in GaAs nanowires. While this phenomenon is in sharp contrast to the textbook knowledge, it is expected to occur widely in nanostructures. This work indicates that the super recoverable deformation in nanomaterials is not simple elastic or reversible plastic deformation in nature, but the coupling of both.

  9. 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

    for future low-cost, high-efficiency photovoltaics. KEYWORDS: Nanowires, solar cells, gallium arsenide, axial.58% efficiency. Simulations show that axial junctions are more tolerant to doping variation than radial junctions and shallow junctions are essential for a high extraction efficiency. Our approach opens up great opportunity

  10. dc field-emission analysis of GaAs and plasma-source ion-implanted stainless steel

    SciTech Connect (OSTI)

    C. Hernandez; T. Wang; T. Siggins; D. Bullard; H. F. Dylla; C. Reece; N. D. Theodore; D. M. Manos

    2003-06-01T23:59:59.000Z

    Field-emission studies have been performed on a GaAs wafer and a sample of its stainless-steel (SS) support electrode that are part of a photocathode gun for the 10 kW Upgrade infrared free electron laser at Jefferson Lab. The objective of the studies presented here is to characterize the effect of both the cleanliness of the wafer and the plasma-source ion-implanted layer on the electrode to suppress field emission. Field emission is the limiting factor to achieve the required 6 MV/m at the surface of the wafer. Potential field emitters are first located on the surface of 1 in. diameter samples with a dc scanning field-emission microscope at 60 MV/m, then each emitter is characterized in a scanning electron microscope equipped with an energy dispersive spectrometer. The GaAs wafer was hydrogen cleaned before the study. The results show three emitters caused by indium contamination during wafer handling. The GaAs wafer thus shows good high-voltage characteristics and the need to maintain cleanliness during handling. The SS sample is hand polished with diamond paste to a 1-m surface finish, then implanted with N2/SiO2 in a plasma-source ion-implantation chamber in preparation for the field-emission studies.

  11. Barium iron arsenide, barium cobalt arsenide, barium nickel arsenide single crystals and superconductivity upon cobalt doping

    SciTech Connect (OSTI)

    Ronning, Filip [Los Alamos National Laboratory; Sefat, A S [ORNL; Mcguire, M M [ORNL; Sales, B [ORNL; Jin, R [ORNL; Mandrus, D [ORNL

    2009-01-01T23:59:59.000Z

    The crystal structure and physical properties of BaFe{sub 2}As{sub 2}, BaCo{sub 2}As{sub 2}, and BaNi{sub 2}As{sub 2} single crystals are surveyed. BaFe{sub 2}As{sub 2} gives a magnetic and structural transition at T{sub N} = 132(1) K, BaCo{sub 2}As{sub 2} is a paramagnetic metal, while BaNi{sub 2}As{sub 2} has a structural phase transition at T{sub 0} = 131 K, followed by superconductivity below {Tc} = 0.69 K. The bulk superconductivity in Co-doped BaFe{sub 2}As{sub 2} below {Tc} = 22 K is demonstrated by resistivity, magnetic susceptibility, and specific heat data. In contrast to the cuprates, the Fe-based system appears to tolerate considerable disorder in the transition metal layers. First principles calculations for BaFe{sub 1.84}Co{sub 0.16}As{sub 2} inter-band scattering due to Co is weak.

  12. 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.

    2010-05-23T23:59:59.000Z

    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.

  13. X-ray pump optical probe cross-correlation study of GaAs

    SciTech Connect (OSTI)

    Durbin, S.M.; Clevenger, T.; Graber, T.; Henning, R. (Purdue); (UC)

    2012-09-10T23:59:59.000Z

    Ultrafast dynamics in atomic, molecular and condensed-matter systems are increasingly being studied using optical-pump, X-ray probe techniques where subpicosecond laser pulses excite the system and X-rays detect changes in absorption spectra and local atomic structure. New opportunities are appearing as a result of improved synchrotron capabilities and the advent of X-ray free-electron lasers. These source improvements also allow for the reverse measurement: X-ray pump followed by optical probe. We describe here how an X-ray pump beam transforms a thin GaAs specimen from a strong absorber into a nearly transparent window in less than 100 ps, for laser photon energies just above the bandgap. We find the opposite effect - X-ray induced optical opacity - for photon energies just below the bandgap. This raises interesting questions about the ultrafast many-body response of semiconductors to X-ray absorption, and provides a new approach for an X-ray/optical cross-correlator for synchrotron and X-ray free-electron laser applications.

  14. 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

    2007-05-01T23:59:59.000Z

    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.

  15. Nuclear radiation detectors based on a matrix of ion-implanted p-i-n diodes on undoped GaAs epilayers

    SciTech Connect (OSTI)

    Baryshnikov, F. M.; Britvich, G. I.; Chernykh, A. V.; Chernykh, S. V.; Chubenko, A. P.; Didenko, S. I.; Koltsov, G. I. [National University of Science and Technology 'MISIS', Leninskiy prospect 4, 119049 Moscow (Russian Federation); Institute for High Energy Physics, Polshhad nauki 1, 142281 Protvino (Russian Federation); National University of Science and Technology 'MISIS', Leninskiy prospect 4, 119049 Moscow (Russian Federation); P.N. Lebedev Physical Institute of the RAS, Leninskiy prospect 53, 119991 Moscow (Russian Federation); National University of Science and Technology 'MISIS', Leninskiy prospect 4, 119049 Moscow (Russian Federation)

    2012-11-06T23:59:59.000Z

    Samples of nuclear detectors which represent matrices of p-i-n diodes were fabricated based on undoped gallium arsenide epitaxial layers by ion implantation technology. The detectors have a size of the active area of 0.4 Multiplication-Sign 0.4 and 0.9 Multiplication-Sign 0.9 cm{sup 2}. Electrical characteristics of fabricated detectors and results of measurements of fast neutrons spectra of {sup 241}Am-Be source by the recoil protons method are discussed.

  16. 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)

    2001-01-01T23:59:59.000Z

    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.

  17. 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)

    2014-04-28T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

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

    2013-08-19T23:59:59.000Z

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

  19. 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

    2006-10-22T23:59:59.000Z

    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.

  20. Impact of heavy hole-light hole coupling on optical selection rules in GaAs quantum dots

    SciTech Connect (OSTI)

    Belhadj, T.; Amand, T.; Kunz, S.; Marie, X.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Kunold, A. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Departamento de Ciencias Basicas, UAM-A, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Simon, C.-M. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); CNRS-UPS, LCAR, IRSAMC, Universite de Toulouse, 31062 Toulouse (France); Kuroda, T.; Abbarchi, M.; Mano, T.; Sakoda, K. [National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044 (Japan)

    2010-08-02T23:59:59.000Z

    We report strong heavy hole-light hole mixing in GaAs quantum dots grown by droplet epitaxy. Using the neutral and charged exciton emission as a monitor we observe the direct consequence of quantum dot symmetry reduction in this strain free system. By fitting the polar diagram of the emission with simple analytical expressions obtained from k{center_dot}p theory we are able to extract the mixing that arises from the heavy-light hole coupling due to the geometrical asymmetry of the quantum dot.

  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.

    2009-05-19T23:59:59.000Z

    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. High-field electroluminescence in semiconductor tunnel junctions with a Mn-doped GaAs layer

    SciTech Connect (OSTI)

    Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-0033 (Japan); Yatsui, Takashi; Ohtsu, Motoichi; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nanophotonics Research Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2014-09-21T23:59:59.000Z

    We investigated high-field electroluminescence (EL) in semiconductor tunnel junctions with a Mn-doped GaAs layer (here, referred to as GaAs:Mn). Besides the band-gap emission of GaAs, the EL spectra show visible light emissions with two peaks at 1.94?eV and 2.19?eV, which are caused by d-d transitions of the Mn atoms excited by hot electrons. The threshold voltages for band-gap and visible light EL in the tunnel junctions with a GaAs:Mn electrode are 1.3?V higher than those of GaAs:Mn excited by hot holes in reserve biased p{sup +}-n junctions, which is consistent with the hot carrier transport in the band profiles of these structures. Our EL results at room temperature show that the electron temperature in GaAs:Mn can be as high as ?700?K for a low input electrical power density of 0.4?W/cm{sup 2}, while the lattice temperature of the GaAs:Mn layer can be kept at 340?K.

  3. ELSEWER Journal of Magnetism and Magnetic Materials 169 (1997) 261-270 Superparamagnetic behavior of Fe,GaAs precipitates in GaAs

    E-Print Network [OSTI]

    Woodall, Jerry M.

    ELSEWER Journal of Magnetism and Magnetic Materials 169 (1997) 261-270 Superparamagnetic behavior; revised 6 December 1996 Abstract We present magnetization measurements on Fe3GaAs clusters distributed-dependent magnetization well above the blocking temperature indicate a particle size distribution in agreement

  4. Self-cleaning and surface recovery with arsine pretreatment in ex situ atomic-layer-deposition of Al2O3 on GaAs

    E-Print Network [OSTI]

    /Thomas Swan close-coupled showerhead cold-wall MOCVD system. The buffer epilayers of GaAs were grown on 2 in for these interfaces. In addition, when designing an in situ MOCVD process, the typical TMA/H2O is incompatible

  5. Metal-insulator-semiconductor structure on low-temperature grown GaAs M. Young, W. Li, and T. P. Ma

    E-Print Network [OSTI]

    Woodall, Jerry M.

    Metal-insulator-semiconductor structure on low-temperature grown GaAs A. Chen,a M. Young, W. Li Received 28 July 2006; accepted 30 October 2006; published online 7 December 2006 The metal-insulator dielectrics and metal-insulator-semiconductor MIS structures; for ex- ample, in situ deposited Ga2O3 Gd2O3

  6. Control of the dephasing process due to many-body interactions among excitons by using non-Markovian effect in GaAs single quantum well

    SciTech Connect (OSTI)

    Ogawa, Y.; Minami, F. [Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan)

    2013-12-04T23:59:59.000Z

    We show the coherent control of dephasing process of exciton polarization due to heavy hole-heavy hole and heavy hole-light hole scatterings in a GaAs single quantum well. The memory time of the exction scattering is estimated as 0.47 ps.

  7. Vacancy migration, adatom motion, a.nd atomic bistability on the GaAs(110) surface studied by scanning tunneling microscopy

    E-Print Network [OSTI]

    Vacancy migration, adatom motion, a.nd atomic bistability on the GaAs(110) surface studied temperature are reported. The slow dynamic behavior of vacancies and As adatoms can be resolved within a time scale of about one minute, The vacancies and As adatoms are observed to move preferably along the [110

  8. Molecular Beam Epitaxial Growth of Bi2Te3 and Sb2Te3 Topological Insulators on GaAs (111) Substrates: A Potential Route to Fabricate Topological Insulator p-n Junction

    E-Print Network [OSTI]

    Zhaoquan Zeng; Timothy A. Morgan; Dongsheng Fan; Chen Li; Yusuke Hirono; Xian Hu; Yanfei Zhao; Joon Sue Lee; Zhiming M. Wang; Jian Wang; Shuiqing Yu; Michael E. Hawkridge; Mourad Benamara; Gregory J. Salamo

    2013-03-11T23:59:59.000Z

    High quality Bi2Te3 and Sb2Te3 topological insulators films were epitaxially grown on GaAs (111) substrate using solid source molecular beam epitaxy. Their growth and behavior on both vicinal and non-vicinal GaAs (111) substrates were investigated by reflection high-energy electron diffraction, atomic force microscopy, x-ray diffraction, and high resolution transmission electron microscopy. It is found that non-vicinal GaAs (111) substrate is better than a vicinal substrate to provide high quality Bi2Te3 and Sb2Te3 films. Hall and magnetoresistance measurements indicate that p type Sb2Te3 and n type Bi2Te3 topological insulator films can be directly grown on a GaAs (111) substrate, which may pave a way to fabricate topological insulator p-n junction on the same substrate, compatible with the fabrication process of present semiconductor optoelectronic devices.

  9. Kinetics of band bending and electron affinity at GaAs(001) surface with nonequilibrium cesium overlayers

    SciTech Connect (OSTI)

    Zhuravlev, A. G.; Savchenko, M. L.; Paulish, A. G.; Alperovich, V. L. [Rzhanov Institute of Semiconductor Physics, Lavrentieva, 13, 630090 Novosibirsk, Russia and Novosibirsk State University, Pirogova, 2, 630090 Novosibirsk (Russian Federation); Scheibler, H. E.; Jaroshevich, A. S. [Rzhanov Institute of Semiconductor Physics, Lavrentieva, 13, 630090 Novosibirsk (Russian Federation)

    2013-12-04T23:59:59.000Z

    The dosage dependences of surface band bending and effective electron affinity under cesium deposition on the Ga-rich GaAs(001) surface, along with the relaxation of these electronic properties after switching off the Cs source are experimentally studied by means of modified photoreflectance spectroscopy and photoemission quantum yield spectroscopy. At small Cs coverages, below half of a monolayer, additional features in the dosage dependence and subsequent downward relaxation of the photoemission current are determined by the variations of band bending. At coverages above half of a monolayer the upward relaxation of the photocurrent is caused supposedly by the decrease of the electron affinity due to restructuring in the nonequilibrium cesium overlayer.

  10. 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 [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Somintac, Armando; Defensor, Michael; Awitan, Fritz Christian B.; Jaculbia, Rafael B.; Salvador, Arnel [National Institute of Physics, University of the Philippines, Diliman, Quezon City 1101 (Philippines); Garcia, Alipio [Department of Physical Sciences, University of the Philippines, Baguio City 2600 (Philippines)

    2009-06-08T23:59:59.000Z

    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.

  11. Perpendicular-to-Parallel Spin Reorientation in a Mn-Doped GaAs Quantum Canting or Phase Separation

    SciTech Connect (OSTI)

    Fishman, Randy Scott [ORNL; Reboredo, Fernando A [ORNL; Brandt, Alex B [ORNL; Moreno, Juana [University of North Dakota, Grand Forks

    2007-01-01T23:59:59.000Z

    It is well known that the magnetic anisotropy in a compressively-strained Mn-doped GaAs film changes from perpendicular to parallel with increasing hole concentration p. We study this reorientation transition at T = 0 for a quantum well with Mn impurities confined to the z = 0 plane. With increasing p, the angle 0 that minimizes the energy E increases continuously from 0 (perpendicular anisotropy) to /2 (parallel anisotropy) within some range of p. The shape of Emin(p) suggests that the quantum well becomes phase separated with regions containing low hole concentrations and perpendicular moments interspersed with other regions containing high hole concentrations and parallel moments. However, consideration of the Coulomb energy costs associated with phase separation suggests that the true magnetic state in the transition region is canted with 0 < < /2.

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

    E-Print Network [OSTI]

    Blount, Samuel Stephen

    2012-06-07T23:59:59.000Z

    the degree ol' MASTER OF SCIEVCE December 19ftg Major Subject: Phys)cs CALCULATIONS OF BOUND AiND RESONAiNT ELECTRONIC STATES FOR THE GaAs [111) (2x2) RECONSTRUCTED SURFACE A Thesis by SAMUEL STEPHEiN BLOUNT Approved as to style and content by...), ? 3eV. & E & 2eV 8] (0. 2859, 0. 2268), ? 13eV. & E & ? 8eV. . 82 (0. 2859, 0. 2268). ? 8el'. & E & ? 3eV. . . 83 (0. 2859, 0. 2268), ? 3eV. & E & 2eV. 84 (0. 3569, 0, 2268), ? 13eV ( E & ? 8eV. . 76 (0. 3569, 0. 2268), ? 8eV. & E & ? 3eV. . . 77...

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

    SciTech Connect (OSTI)

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

    1990-01-01T23:59:59.000Z

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

  14. Electron Transport Behavior on Gate Length Scaling in Sub-50 nm GaAs Metal Semiconductor Field Effect Transistors

    SciTech Connect (OSTI)

    Han, Jaeheon [Department of Electronic Engineering, Kangnam University, 111 Gugal-dong, Giheung-gu, Yongin-city, Gyeonggi-do, Korea 446-702 (Korea, Republic of)

    2011-12-23T23:59:59.000Z

    Short channel GaAs Metal Semiconductor Field Effect Transistors (MESFETs) have been fabricated with gate length to 20 nm, in order to examine the characteristics of sub-50 nm MESFET scaling. Here the rise in the measured transconductance is mainly attributed to electron velocity overshoot. For gate lengths below 40 nm, however, the transconductance drops suddenly. The behavior of velocity overshoot and its degradation is investigated and simulated by using a transport model based on the retarded Langevin equation (RLE). This indicates the existence of a minimum acceleration length needed for the carriers to reach the overshoot velocity. The argument shows that the source resistance must be included as an internal element, or appropriate boundary condition, of relative importance in any model where the gate length is comparable to the inelastic mean free path of the carriers.

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

    SciTech Connect (OSTI)

    Zhang, W., E-mail: xiaotur@gmail.com; Zhang, D.; Yuan, S. J.; Huang, Z. C.; Zhai, Y. [Department of Physics, Southeast University, Nanjing 211189 (China); Wong, P. K. J. [NanoElectronics Group, MESA Institute for Nanotechnology, University of Twente, P. O. Box 217, 7500 AE Enschede (Netherlands); Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Wu, J. [Department of Physics, University of York, York YO10 5DD (United Kingdom); Xu, Y. B. [Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York, YO10 5DD (United Kingdom)

    2014-10-15T23:59:59.000Z

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

    SciTech Connect (OSTI)

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

    1995-10-01T23:59:59.000Z

    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.

  17. Investigation of ultrafast photothermal surface expansion and diffusivity in GaAs via laser-induced dynamic gratings

    SciTech Connect (OSTI)

    Pennington, D.M.

    1992-04-01T23:59:59.000Z

    This thesis details the first direct ultrafast measurements of the dynamic thermal expansion of a surface and the temperature dependent surface thermal diffusivity using a two-color reflection transient grating technique. Studies were performed on p-type, n-type, and undoped GaAs(100) samples over a wide range of temperatures. By utilizing a 90 fs ultraviolet probe with visible excitation beams, the effects of interband saturation and carrier dynamics become negligible; thus lattice expansion due to heating and subsequent contraction caused by cooling provided the dominant influence on the probe. At room temperature a rise due to thermal expansion was observed, corresponding to a maximum net displacement of {approximately} 1 {Angstrom} at 32 ps. The diffracted signal was composed of two components, thermal expansion of the surface and heat flow away from the surface, thus allowing a determination of the rate of expansion as well as the surface thermal diffusivity, D{sub S}. By varying the fringe spacing of the grating, this technique has the potential to separate the signal contributions to the expansion of the lattice in the perpendicular and parallel directions. In the data presented here a large fringe spacing was used, thus the dominant contribution to the rising edge of the signal was expansion perpendicular to the surface. Comparison of he results with a straightforward thermal model yields good agreement over a range of temperatures (20--300{degrees}K). Values for D{sub S} in GaAs were measured and found to be in reasonable agreement with bulk values above 50{degrees}K. Below 50{degrees}K, D{sub S} were determined to be up to an order of magnitude slower than the bulk diffusivity due to increased phonon boundary scattering. The applicability and advantages of the TG technique for studying photothermal and photoacoustic phenomena are discussed.

  18. Impact of artificial lateral quantum confinement on exciton-spin relaxation in a two-dimensional GaAs electronic system

    SciTech Connect (OSTI)

    Kiba, Takayuki, E-mail: tkiba@ist.hokudai.ac.jp; Murayama, Akihiro [Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo (Japan); CREST Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo (Japan); Tanaka, Toru [Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo (Japan); Tamura, Yosuke [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai (Japan); Higo, Akio [WPI-AIMR, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai (Japan); Thomas, Cedric [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai (Japan); CREST Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo (Japan); Samukawa, Seiji [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai (Japan); WPI-AIMR, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai (Japan); CREST Japan Science and Technology Agency, 5 Sanbancho, Chiyoda-ku, Tokyo (Japan)

    2014-10-15T23:59:59.000Z

    We demonstrate the effect of artificial lateral quantum confinement on exciton-spin relaxation in a GaAs electronic system. GaAs nanodisks (NDs) were fabricated from a quantum well (QW) by top-down nanotechnology using neutral-beam etching aided by protein-engineered bio-nano-templates. The exciton-spin relaxation time was 1.4 ns due to ND formation, significantly extended compared to 0.44 ns for the original QW, which is attributed to weakening of the hole-state mixing in addition to freezing of the carrier momentum. The temperature dependence of the spin-relaxation time depends on the ND thickness, reflecting the degree of quantum confinement.

  19. 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

  20. Discrimination between energy transfer and back transfer processes for GaAs host and Er luminescent dopants using electric response analysis

    SciTech Connect (OSTI)

    Ishii, Masashi, E-mail: ISHII.Masashi@nims.go.jp [National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0047 (Japan); Koizumi, Atsushi; Fujiwara, Yasufumi [Division of Materials and Manufacturing Science, Graduate School of Engineering Osaka University, Suita, Osaka 565-0871 (Japan); Takeda, Yoshikazu [Nagoya Industrial Science Research Institute, Nagoya, Aichi 464-0819 (Japan)

    2014-04-07T23:59:59.000Z

    The energy transfer and back transfer processes of GaAs co-doped with Er and O (GaAs:Er,O) were experimentally distinguished by using a frequency response analysis of the AC photocurrent. The results were achieved by using the difference in the frequency dispersion between (1) the dispersion of the energy transfer, which is triggered by the trapping of free charges in the GaAs host and is represented with the Debye relaxation response and (2) the dispersion of the energy back transfer, which is induced by non-radiative transition of 4f bound electrons in the Er dopants and is described with a Lorentzian. The Debye relaxation response found in GaAs:Er,O provided a charge trapping time that was dependent on temperature, which was well correlated with the thermal quenching property of intense intra-4f-shell luminescence. The spectral shape of the Lorentzian dependence on the temperature was explained with the thermal excitation of Er 4f electrons and release of trapped charges in GaAs. The thermal excitation and release of charges consistently explained the characteristics of weak 4f luminescence in low- and high-temperature regions, respectively.

  1. Metal organic chemical vapor deposition of 111-v compounds on silicon

    DOE Patents [OSTI]

    Vernon, Stanley M. (Wellesley, MA)

    1986-01-01T23:59:59.000Z

    Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

  2. Deep Levels in p-Type InGaAsN Lattice Matched to GaAs

    SciTech Connect (OSTI)

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

    1999-03-02T23:59:59.000Z

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

  3. Selfsimilar and fractal analysis of n-type delta-doped quasiregular GaAs quantum wells

    SciTech Connect (OSTI)

    García-Cervantes, H.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)

    2014-05-15T23:59:59.000Z

    We study the electronic structure of n-type delta-doped quantum wells in GaAs in which the multiple well system is built according to the Fibonacci sequence. The building blocks A and B correspond to delta-doped wells with impurities densities n{sub 2DA} and n{sub 2DB}, and the same well width. The Thomas-Fermi approximation, the semi-empirical sp{sub 3}s* tight-binding model including spin, the Surface Green Function Matching method and the Transfer Matrix approach were implemented to obtain the confining potential, the electronic structure and the selfsimilarity of the spectrum. The fragmentation of the electronic spectra is observed whenever the building blocks A and B interact and it increases as the difference of impurities density between A and B increases as well. The wave function of the first sate of the fragmented bands presents critical characteristics, this is, it is not a localized state nor a extended one as well as it has selfsimilar features. So, the quasiregular characteristics are preserved irrespective of the complexity of the system and can affect the performance of devices based on these structures.

  4. 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 CenterFranconia, Virginia: Energy Resources Jump to: navigation,Ohio:Greer County is a county inAl.,20454°,

  5. Designing Asynchronous Circuits in Gallium Arsenide

    E-Print Network [OSTI]

    Martin, Alain

    3.2.2 Super Buffered Fet Logic : : : : : : : : : : : : : : : : : 18 4 A New Logic Family 21 4.1 Input Stage : : : : : : : : : : : : : : : : : : : : : : : : : : : : 21 4.1.1 Inverter : : : : : : : : : : : : : : : : : : : : : : : : 34 5.2.2 Output stage : : : : : : : : : : : : : : : : : : : : : : : 36 5.2.3 Delay model and power

  6. Optical and digital GaAs technologies for signal-processing applications; Proceedings of the Meeting, Orlando, FL, Apr. 16-18, 1990

    SciTech Connect (OSTI)

    Bendett, M.P.; Butler, D.H., Jr.; Prabhakar, A.; Yang, A.; (Honeywell, Inc., Minneapolis, MN; Booz, Allen and Hamilton, Inc., Bethesda, MD; DARPA, Arlington, VA)

    1990-01-01T23:59:59.000Z

    Practical problems that need to be solved for the introduction of optical modules into processing systems are reviewed. Some papers deal with the state of the art in such key devices as Bragg cells, spatial light modulators, and fast CCDs. Issues unique to optical packaging are also highlightened. New architectures to enable real-time operations are demonstrated, and optical interconnects for parallel processors are discussed. Particular attention is given to the status and operational advantages of government-sponsored efforts to upgrade existing military systems with digital GaAs signal processors and the state of the art in computer-aided design and advanced system architectures.

  7. 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.

    2012-03-01T23:59:59.000Z

    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.

  8. Infrared spectroscopy of lattice vibrations in ZnTe/CdTe superlattices with quantum dots on the GaAs substrate with the ZnTe buffer layer

    SciTech Connect (OSTI)

    Kozyrev, S. P. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)], E-mail: skozyrev@sci.lebedev.ru

    2009-03-15T23:59:59.000Z

    The results of the analysis of the infrared lattice reflectance spectra of multiperiod ZnTe/CdTe superlattices with CdTe quantum dots are reported. The samples are grown by molecular beam epitaxy on the GaAs substrate with the ZnTe buffer layer. Due to the large number of periods of the superlattices, it is possible to observe CdTe-like vibration modes in the quantum dots, i.e., the dislocation-free stressed islands formed during the growth due to relaxation of elastic stresses between the ZnTe and CdTe layers are markedly different in their lattice parameters. From the frequency shifts of the CdTe- and ZnTe-like vibration modes with respect to the corresponding modes in the unstressed materials, it is possible to estimate the level of elastic stresses.

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

    SciTech Connect (OSTI)

    Yuan, Zaoshi [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Chemical Engineering, Stanford University, Stanford, California 94305-5025 (United States); Shimamura, Kohei [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395 (Japan); Shimojo, Fuyuki [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States) [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States); Department of Physics, Kumamoto University, Kumamoto 860-8555 (Japan); Nakano, Aiichiro [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)] [Collaboratory for Advanced Computing and Simulations, Department of Physics and Astronomy, Department of Computer Science, and Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089-0242 (United States)

    2013-08-21T23:59:59.000Z

    While nanowires and nanosheets (NSs) grown on lattice-mismatched substrates have a number of promising technological applications such as solar cells, generation of misfit dislocations (MFDs) at their interfaces is a major concern for the efficiency of these devices. Here, combined molecular-dynamics and quantum-mechanical simulations are used to study MFDs at the interface between a GaAs NS and a Si substrate. Simulation results show the existence of a critical NS thickness, below which NSs are grown free of MFDs. The calculated critical thickness value is consistent with available experimental observations. Charge transfer at the MFD core is found to modify the electronic band profile at the GaAs/Si interface significantly. These effects should have profound impacts on the efficiency of lattice-mismatched NS devices.

  10. Repetition of the shape of the ultrafast self-modulation of the optical absorption spectrum upon varying the energy of pulse of GaAs pumping

    SciTech Connect (OSTI)

    Ageeva, N. N.; Bronevoi, I. L., E-mail: bil@cplire.ru; Zabegaev, D. N.; Krivonosov, A. N. [Russian Academy of Sciences, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)

    2010-10-15T23:59:59.000Z

    Ultrafast self-modulation of the fundamental optical absorption emerges during intense picosecond optical pumping of GaAs and, according to the main assumption, reflects self-oscillations of depletion of electron populations in the conduction band. In this study, the quantitatively confirmed explanation of previously experimentally found cyclic repetition of the form of ultrafast self-modulation of the absorption spectrum upon varying the energy of the pumping pulse and fixed delay between pumping and probing (the measurement of absorption) is given. Repetition of the shape is explained by varying the phase of self-oscillations of the optical absorption. The explanation is based on the previously found experimentally dependence of the frequency of self-oscillations of absorption on the pumping energy. Therefore, this is also a new confirmation of the mentioned dependence (which satisfactorily coincides with a similar calculated dependence of the frequency of self-oscillations of depletion of populations).

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

    SciTech Connect (OSTI)

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

    2013-11-25T23:59:59.000Z

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

  12. Co doping enhanced giant magnetocaloric effect in Mn{sub 1-x}Co{sub x}As films epitaxied on GaAs (001)

    SciTech Connect (OSTI)

    Xu, P. F.; Nie, S. H.; Meng, K. K.; Wang, S. L.; Chen, L.; Zhao, J. H. [State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2010-07-26T23:59:59.000Z

    A giant magnetocaloric effect was found in series of Mn{sub 1-x}Co{sub x}As films epitaxied on GaAs (001). The maximum magnetic entropy change caused by a magnetic field of 4 T is as large as 25 J/kg K around room temperature, which is about twice the value of pure MnAs film. The observed small thermal hysteresis is more suitable for practical application. Growing of layered Mn{sub 1-x}Co{sub x}As films with Co concentration changing gradually may draw layered active magnetic regenerator refrigerators closer to practical application. Our experimental result may provide the possibility for the combination of magnetocaloric effect and microelectronic circuitry.

  13. IEEE ELECTRON DEVICE LETTERS, VOL. 24, NO. 4, APRIL 2003 227 RF MEMS Switches Fabricated on

    E-Print Network [OSTI]

    Cetiner, Bedri A.

    with superior performance over con- ventional semiconductor devices [4]­[7]. Typically, RF MEMS switches-resistivity silicon wafers, gallium arsenide (GaAs) wafers, and quartz substrates using semiconductor Manuscript and surface planarization of wide metal lines prior to deposition of a metal membrane bridge, which poses

  14. but the resolution of 2 was not sufficient to determine whether the C18

    E-Print Network [OSTI]

    Thibado, Paul M.

    but the resolution of 2 was not sufficient to determine whether the C18 O emission was con- fined and AUI for funding the PT link project and to Western New Mexico Telephone Company for the use arsenide (GaAs) without losing their polar- ization, so that coherent transport through the active region

  15. Structural properties of Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} topological insulators grown by molecular beam epitaxy on GaAs(001) substrates

    SciTech Connect (OSTI)

    Liu, X.; Leiner, J.; Dobrowolska, M.; Furdyna, J. K. [Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Smith, D. J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Fan, J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Center for Photonics Innovation, Arizona State University, Tempe, Arizona 85287 (United States); Zhang, Y.-H. [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); Cao, H.; Chen, Y. P. [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Kirby, B. J. [Center for Neutron Research, NIST, Gaithersburg, Maryland 20899 (United States)

    2011-10-24T23:59:59.000Z

    Thin films of Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} have been grown on deoxidized GaAs(001) substrates using molecular beam epitaxy. Cross-sectional transmission electron microscopy established the highly parallel nature of the Te(Se)-Bi-Te(Se)-Bi-Te(Se) quintuple layers deposited on the slightly wavy GaAs substrate surface and the different crystal symmetries of the two materials. Raman mapping confirmed the presence of the strong characteristic peaks reported previously for these materials in bulk form. The overall quality of these films reveals the potential of combining topological insulators with ferromagnetic semiconductors for future applications.

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

    SciTech Connect (OSTI)

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

    2003-06-16T23:59:59.000Z

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

  17. Spin decoherence in n-type GaAs: The effectiveness of the third-body rejection method for electron-electron scattering

    SciTech Connect (OSTI)

    Marchetti, Gionni, E-mail: gionnimarchetti@gmail.com; Hodgson, Matthew, E-mail: matthew.hodgson@york.ac.uk; D'Amico, Irene, E-mail: irene.damico@york.ac.uk [Department of Physics, University of York, York, Heslington YO10 5DD (United Kingdom)

    2014-10-28T23:59:59.000Z

    We study the spin decoherence in n-type bulk GaAs for moderate electronic densities at room temperature using the Ensemble Monte Carlo method. We demonstrate that a technique called “third-body rejection method” devised by B. K. Ridley, J. Phys. C: Solid State Phys. 10, 1589 (1977) can be successfully adapted to Ensemble Monte Carlo method and used to tackle the problem of the electron-electron contribution to spin decoherence in the parameter region under study, where the electron-electron interaction can be reasonably described by a Yukawa potential. This scattering technique is employed in a doping region where one can expect that multiple collisions may play a role in carrier dynamics. By this technique, we are able to calculate spin relaxation times which are in very good agreement with the experimental results found by Oertel et al., Appl. Phys. Lett. 93, 13 (2008). Through this method, we show that the electron-electron scattering is overestimated in Born approximation, in agreement with previous results obtained by C. A. Kukkonen and H. Smith, Phys. Rev. B 8, 4601 (1973).

  18. IR spectroscopy of lattice vibrations and comparative analysis of the ZnTe/CdTe quantum-dot superlattices on the GaAs substrate and with the ZnTe and CdTe buffer layers

    SciTech Connect (OSTI)

    Kozyrev, S. P. [Russian Academy of Sciences, Lebedev Institute of Physics (Russian Federation)], E-mail: skozyrev@sci.lebedev.ru

    2009-07-15T23:59:59.000Z

    A comparative analysis of multiperiod ZnTe/CdTe superlattices with the CdTe quantum dots grown by molecular beam epitaxy on the GaAs substrate with the ZnTe and CdTe buffer layers is carried out. The elastic-stress-induced shifts of eigenfrequencies of the modes of the CdTe- and ZnTe-like vibrations of materials forming similar superlattices but grown on different buffer ZnTe and CdTe layers are compared. The conditions of formation of quantum dots in the ZnTe/CdTe superlattices on the ZnTe and CdTe buffer layers differ radically.

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

    SciTech Connect (OSTI)

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

    2014-11-03T23:59:59.000Z

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

  20. Direct exchange interaction of localized spins associated with unpaired sp electrons in Be-doped low-temperature-grown GaAs layers

    SciTech Connect (OSTI)

    Bae, K. W.; Mohamed, Mohd Ambri; Jung, D. W.; Otsuka, N. [School of Materials Science Japan Advanced Institute of Science and Technology Asahidai 1-1, Nomishi, Ishikawa 923-1292 (Japan)

    2011-04-01T23:59:59.000Z

    Beryllium-doped GaAs layers grown at low temperatures by molecular-beam epitaxy contain localized spins associated with unpaired sp electrons of As{sub Ga}{sup +} ions. Interactions of these localized spins are investigated by measuring the magnetization with a superconducting quantum interference device and the peak-to-peak width of electron paramagnetic resonance (EPR) spectra for samples with different spin concentrations ranging from 3 x 10{sup 18} to 2.0 x 10{sup 19} cm{sup -3}. The results show that localized spins in this material antiferromagnetically interact on each other via direct exchange. From the analysis of the temperature dependence and field dependence of the magnetization on the basis of the Curie-Weiss law and the molecular-field approximation, exchange energy of each sample was derived. The dependence of the exchange energy on the concentration of localized spins is reasonably explained by a model of direct exchange, which results from the overlapping of wave functions of unpaired electrons at As{sub Ga}{sup +} ions. The peak-to-peak width of EPR spectra increases with an increase in the spin concentration at low temperatures, whereas it decreases with an increase in the temperature for samples with high spin concentrations. These EPR results also show that significant exchange interactions indeed occur between localized spins in this material. These effects of direct exchange interactions between localized spins can clearly be observed at their average distances of around 4 nm, which implies a considerably large spatial extension of the wave function of an unpaired sp electron around an As{sub Ga}{sup +} ion.

  1. RELATIVE ATTENUATION CHARACTERISTICS OF SOME SHIELDING MATERIALS FOR PuB NEUTRONS

    E-Print Network [OSTI]

    Bringham, P.S.

    2010-01-01T23:59:59.000Z

    1: Polyethylene Water Spodumene-gypsum Gypsum, wet and dryconstituents of the spodumene-gypsum, and gypsum shields.SPODUMENK·,GYPSUM SHIELD 30% Spodumene by weight 40% Gypsum

  2. Molecular beam epitaxial growth of Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} topological insulators on GaAs (111) substrates: a potential route to fabricate topological insulator p-n junction

    SciTech Connect (OSTI)

    Zeng, Zhaoquan; Morgan, Timothy A.; Li, Chen; Hirono, Yusuke; Hu, Xian; Hawkridge, Michael E.; Benamara, Mourad; Salamo, Gregory J. [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States)] [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Fan, Dongsheng; Yu, Shuiqing [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States) [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Department of Electrical Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); Zhao, Yanfei [International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 (China)] [International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 (China); Lee, Joon Sue [The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States)] [The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Wang, Jian [International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 (China) [International Center for Quantum Materials, School of Physics, Peking University, Beijing, 100871 (China); The Center for Nanoscale Science and Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Wang, Zhiming M. [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States) [Arkansas Institute for Nanoscale Material Sciences and Engineering, University of Arkansas, Fayetteville, AR 72701 (United States); State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Engineering Research Center for Semiconductor Integrated Technology, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China)

    2013-07-15T23:59:59.000Z

    High quality Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} topological insulators films were epitaxially grown on GaAs (111) substrate using solid source molecular beam epitaxy. Their growth and behavior on both vicinal and non-vicinal GaAs (111) substrates were investigated by reflection high-energy electron diffraction, atomic force microscopy, X-ray diffraction, and high resolution transmission electron microscopy. It is found that non-vicinal GaAs (111) substrate is better than a vicinal substrate to provide high quality Bi{sub 2}Te{sub 3} and Sb{sub 2}Te{sub 3} films. Hall and magnetoresistance measurements indicate that p type Sb{sub 2}Te{sub 3} and n type Bi{sub 2}Te{sub 3} topological insulator films can be directly grown on a GaAs (111) substrate, which may pave a way to fabricate topological insulator p-n junction on the same substrate, compatible with the fabrication process of present semiconductor optoelectronic devices.

  3. Is Gypsum Application Beneficial to Soil? Francisco J. Arriaga

    E-Print Network [OSTI]

    Balser, Teri C.

    ). · Response to calcium application unlikely even in soils testing low or very low, except when growing S demand (alfalfa, canola and brassicas), in sandy soils and soils low in organic matter. · Soils with low or medium potential for sulfate retention (sands and loamy sands), and with no recent manure applications

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

    E-Print Network [OSTI]

    Gardiner, Duane

    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...

  5. Utilization of by-product gypsum in construction

    E-Print Network [OSTI]

    Stephenson, Angela Lorraine

    1987-01-01T23:59:59.000Z

    . Neutralization processes with NaOH and Ca(OH) & were studied and stabilization with commercial grade types of portland cement and fly ash was investigated (after different curing periods) to compare relative strengths as applied to road construction.... For phosphogypsum stabilized by portland cement, initial and intermediate stages of strength development obtained for the material, cured for 3 and 7 days at approximate pH levels of 4, 6, and 8 and cement contents of 34 and 64, yielded strengths which increase...

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

    SciTech Connect (OSTI)

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

    2008-06-16T23:59:59.000Z

    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.

  7. Carrier transfer from InAs quantum dots to ErAs metal nanoparticles

    SciTech Connect (OSTI)

    Haughn, C. R.; Chen, E. Y.; Zide, J. M. O.; Doty, M. F., E-mail: doty@udel.edu [Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716 (United States); Steenbergen, E. H.; Bissell, L. J.; Eyink, K. G. [AFRL/RXAN, Wright Patterson AFB, Ohio 45433 (United States)

    2014-09-08T23:59:59.000Z

    Erbium arsenide (ErAs) is a semi-metallic material that self-assembles into nanoparticles when grown in GaAs via molecular beam epitaxy. We use steady-state and time-resolved photoluminescence to examine the mechanism of carrier transfer between indium arsenide (InAs) quantum dots and ErAs nanoparticles in a GaAs host. We probe the electronic structure of the ErAs metal nanoparticles (MNPs) and the optoelectronic properties of the nanocomposite and show that the carrier transfer rates are independent of pump intensity. This result suggests that the ErAs MNPs have a continuous density of states and effectively act as traps. The absence of a temperature dependence tells us that carrier transfer from the InAs quantum dots to ErAs MNPs is not phonon assisted. We show that the measured photoluminescence decay rates are consistent with a carrier tunneling model.

  8. Broadband electrooptic modulators based on gallium arsenide materials

    E-Print Network [OSTI]

    Shamir, Orit A

    2012-01-01T23:59:59.000Z

    Optical Arbitrary Waveform Generation (OAWG) combines frequency combs and frequency-by- frequency pulse shapers to synthesize optical waveforms. The OAWG technique has a wide variety of applications, ranging from high ...

  9. Transport in the quantum critical regime of the iron arsenide...

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

    emerges, one whose thermodynamic and transport properties differ from the unified phenomenology with which we understand conventional metals - the Landau-Fermi liquid theory -...

  10. arsenide solar cells: Topics by E-print Network

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

    Pankaj J Edla; Dr. Bhupendra Gupta 92 Fully Solution-Processed Copper Chalcopyrite Thin Film Solar Cells: Materials Chemistry, Processing, and Device Physics University of...

  11. arsenide gallium nitride: Topics by E-print Network

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

    Lundberga,*, J. Lua , A Abstract The diffusion of indium and gallium in polycrystalline thin film Cu(In,Ga)Se2 layers has been with a larger number of vacancies, that facilitates...

  12. arsenide solar cell: Topics by E-print Network

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

    Pankaj J Edla; Dr. Bhupendra Gupta 92 Fully Solution-Processed Copper Chalcopyrite Thin Film Solar Cells: Materials Chemistry, Processing, and Device Physics University of...

  13. arsenide thin films: Topics by E-print Network

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

    films Engineering Websites Summary: of domain switching and controllability, preventing thin-film and polycrystalline ferroelectrics from the switching mechanisms of...

  14. Synthesis and Characterization of Bulk, Vitreous Cadmium Germanium Arsenide

    E-Print Network [OSTI]

    Rockett, Angus

    is presented to enable fabrication of high-purity, vitreous, crack-free ingots with sizes up to 10 mm diameter are the key function material in several important technological areas such as xerography,1 photovoltaics,2 formation within the CdGexAs2 system has been re- ported for x 5 0.02­1.3.12­18 The basic glass forming

  15. Fabrication of a gated gallium arsenide heterostructure resonant tunneling diode

    E-Print Network [OSTI]

    Kinard, William Brian

    1989-01-01T23:59:59.000Z

    metallization process ivas required because separate potentials must be apphed to the top and base ol' the defined mesas. A potent&al is apphed to the top of the mesas to inject carriers for tunneling through the douhle barrier heterostructures A. rectifying... was a demetal/degrease cleanup process which re- moved any contamination that may have been nn the wal'er. This process ivas followed by deposition of AuGe/Ni on the ivafer's backside which ivill provide an ohmic contact after annealing. The backside...

  16. Synthesis and Characterization of Bulk Vitreous Cadmium Germanium Arsenide.

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security AdministrationcontrollerNanocrystallineForeign Object Damage 3 B. L. Boyce,1Arsenical Fluorescent|

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

    SciTech Connect (OSTI)

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

    2013-09-14T23:59:59.000Z

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

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

    DOE Patents [OSTI]

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

    2001-01-01T23:59:59.000Z

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

  19. Research directions and progress in the SERI advanced high efficiency concept program

    SciTech Connect (OSTI)

    Cole, L.A.; Benner, J.P.

    1984-06-01T23:59:59.000Z

    The inherent electro-optical properties of gallium arsenide (GaAs) and related III-V compounds make this class of semiconductors an optimum choice for use in very high efficiency solar cells. The ability to alloy GaAs with other column III and V elements while maintaining the single crystal zincblende structure allows the photovoltaic properties to be tailored to specific needs. The current understanding and control of the properties of these materials is more advanced than for any other semiconductor except single crystal silicon. For these reasons, the Advanced High Efficiency Concepts Program supports materials research to improve the properties of III-V semiconductors needed to achieve the maximum attainable photovoltaic conversion efficiencies.

  20. Holographic interferometry study of the dissolution and diffusion of gypsum in Jean Colombani

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    and Wilde, 1971) with a Nernst-Hartley equation from the tracer diffusivity of the ions (Jeschke et al

  1. Remediation of brine-contaminated soil using calcium nitrate, gypsum, and straw.

    E-Print Network [OSTI]

    Nielsen, Jennifer I.

    2013-01-01T23:59:59.000Z

    ??Salt-affected soils from point source brine contamination are common in the active oil field in SE Saskatchewan. A remediation process that included dewatering by sub-surface… (more)

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

    E-Print Network [OSTI]

    Janssen, Antonius Hendrick

    1981-01-01T23:59:59.000Z

    . The effect of NaC1 on root number and color intensity of the foliage were not altered by the addition of CaSO . The beneficial effects of CaS04 cou1d not be demonstrated in a peat-styrafoam medium. Acknowledgements I would like to express my sincere... Ca/Na ratios for the NaC1:Ca504 solutions 5 Electrical conductivities (E. C. ) of 2 KNO solutions with i ncreasing CaS04 concent/ations 6 The effects of pH and peat extract on rooting of 'Big Red' cuttings . Page 13 15 44 45 56 LIST...

  3. Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides

    E-Print Network [OSTI]

    Sayles, Todd Allen

    2008-01-01T23:59:59.000Z

    1.5 Superconductivity . . . . . . . . . . . . . . . . . . .and M. B. Maple, ”Superconductivity and non-Fermi liquidSAN DIEGO Magnetism and Superconductiviy in Pr-based Filled

  4. E-Print Network 3.0 - arsenide oxides sr2cro3feas Sample Search...

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

    Microstructures of gallium nitride nanowires synthesized by oxide-assisted method W.S. Shi, Y... synthesized using the recently developed oxide-assisted method by laser...

  5. E-Print Network 3.0 - arsenide-based ternary compounds Sample...

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

    compounds and the Gd6Co1.67Si3 ternary silicide 5. On the contrary... The new ternary silicide Gd5CoSi2 : ... Source: Ecole Polytechnique, Centre de mathmatiques Collection:...

  6. Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides

    E-Print Network [OSTI]

    Sayles, Todd Allen

    2008-01-01T23:59:59.000Z

    1.3 Magnetism . . . . .1.3.3 Itinerant Magnetism . . . . . . . . . . .3.3 Magnetism . . . . . . . . . . . . . . . . . . . . . 3.4

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

    E-Print Network [OSTI]

    Fairchild, Brock Wilson

    1990-01-01T23:59:59.000Z

    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... D. Electron Bes. m Evaporation E. Fabrication of Photolithographic Masks 1, Plain Ring Resonator Mask 2. Notched Resons. tor Mask 3. Linear Resonator Mask 4. Slit Ring Resonator Mask F. Photolithography G. Electroplating H. Layer Removals I...

  8. E-Print Network 3.0 - arsenide integrated circuit Sample Search...

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

    -3:40pm Summary: 02139 A novel epitaxy-on-electronics process for fabricating optoelectronic integrated circuits (OE- ICs... integrated circuit technology base, this...

  9. E-Print Network 3.0 - arsenide p-i-n detectors Sample Search...

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

    Sciences ; Engineering 52 header for SPIE use Integrated cooling for optoelectronic devices Summary: from similar materials. Experimental analysis of an InP p-i-n diode...

  10. E-Print Network 3.0 - arsenide inas quantum Sample Search Results

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

    Nanometer-scale islands that form spontaneously on a semiconductor... and optoelectronic devices, quantum computing, and History, information storage. Highlights, ... Source:...

  11. Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides

    E-Print Network [OSTI]

    Sayles, Todd Allen

    2008-01-01T23:59:59.000Z

    5.11: Zero ?eld electrical resistivity vs temperature ?(T )technique. The electrical resistivity ? vs temperature T5.3: The zero-?eld electrical resistivity ? vs temperature T

  12. E-Print Network 3.0 - arsenide x-ray imaging Sample Search Results

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

    less... materials. Researchers have used the method to make high-performance image sensors, transistors, and solar Source: Rogers, John A. - Department of Materials Science...

  13. Sparse gallium arsenide to silicon metal waferbonding for heterogeneous monolithic microwave integrated circuits

    E-Print Network [OSTI]

    Bickford, Justin Robert

    2008-01-01T23:59:59.000Z

    and Applications, edited by T. M. Tritt, ( Kluwer Academic /and Applications, edited by T. M. Tritt, ( Kluwer Academic /and Applications, edited by T. M. Tritt, ( Kluwer Academic /

  14. E-Print Network 3.0 - arsenide-zinc selenide core-shell Sample...

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

    as 3D Scaffolds for New Materials: from Mechanically Strong Polymer Crosslinked Aerogels Summary: . Those 3D core-shell superstructures are true multifunctional materials...

  15. Magnetism and superconductivi[t]y in Pr-based filled skutterudite arsenides

    E-Print Network [OSTI]

    Sayles, Todd Allen

    2008-01-01T23:59:59.000Z

    in the conduction band The Josephson junction . . . . . .1.4: A diagram of a Josephson junction, consisting of tworings joined by two Josephson junctions. The current through

  16. Fabrication of an optically driven 10 GHz ring resonator on a gallium arsenide substrate

    E-Print Network [OSTI]

    McGregor, Douglas Scott

    1989-01-01T23:59:59.000Z

    /D converters, optical detectors, dc to rf converters, and millimeter-wave or microwave generators. Photoconductors can be easily integrated with microelectronic devices as well as microwave circuits. Recently, an optically excited photoconductive switch... is the barrier height and y, is the electron affinity for the semiconductor. Current flow at a metal-semiconductor barrier is due mainly to majority carriers. The four major current transport methods are thermionic emission over the barrier, quantum...

  17. Sparse gallium arsenide to silicon metal waferbonding for heterogeneous monolithic microwave integrated circuits

    E-Print Network [OSTI]

    Bickford, Justin Robert

    2008-01-01T23:59:59.000Z

    is limited by the cold-wall chamber design and the porousrepeatability. The cold-wall chamber design also limits the

  18. Design, fabrication, and analysis of p-channel arsenide/antimonide hetero-junction tunnel transistors

    SciTech Connect (OSTI)

    Rajamohanan, Bijesh, E-mail: bor5067@psu.edu; Mohata, Dheeraj; Hollander, Matthew; Datta, Suman [Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Zhu, Yan; Hudait, Mantu [Bradley Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Jiang, Zhengping; Klimeck, Gerhard [Department of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47906 (United States)

    2014-01-28T23:59:59.000Z

    In this paper, we demonstrate InAs/GaSb hetero-junction (hetJ) and GaSb homo-junction (homJ) p-channel tunneling field effect transistors (pTFET) employing a low temperature atomic layer deposited high-? gate dielectric. HetJ pTFET exhibited drive current of 35 ?A/?m in comparison to homJ pTFET, which exhibited drive current of 0.3 ?A/?m at V{sub DS}?=??0.5?V under DC biasing conditions. Additionally, with pulsing of 1 ?s gate voltage, hetJ pTFET exhibited enhanced drive current of 85 ?A/?m at V{sub DS}?=??0.5?V, which is the highest reported in the category of III-V pTFET. Detailed device characterization was performed through analysis of the capacitance-voltage characteristics, pulsed current-voltage characteristics, and x-ray diffraction studies.

  19. Analysis of gallium arsenide deposition in a horizontal chemical vapor deposition reactor using massively parallel computations

    SciTech Connect (OSTI)

    Salinger, A.G.; Shadid, J.N.; Hutchinson, S.A. [and others

    1998-01-01T23:59:59.000Z

    A numerical analysis of the deposition of gallium from trimethylgallium (TMG) and arsine in a horizontal CVD reactor with tilted susceptor and a three inch diameter rotating substrate is performed. The three-dimensional model includes complete coupling between fluid mechanics, heat transfer, and species transport, and is solved using an unstructured finite element discretization on a massively parallel computer. The effects of three operating parameters (the disk rotation rate, inlet TMG fraction, and inlet velocity) and two design parameters (the tilt angle of the reactor base and the reactor width) on the growth rate and uniformity are presented. The nonlinear dependence of the growth rate uniformity on the key operating parameters is discussed in detail. Efficient and robust algorithms for massively parallel reacting flow simulations, as incorporated into our analysis code MPSalsa, make detailed analysis of this complicated system feasible.

  20. E-Print Network 3.0 - arsenide photoconductive detectors Sample...

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

    7 Terahertz emission from black silicon M. Theuer,2 Summary: -called photoconductive terahertz emitters and detectors, radiation-damaged silicon on sapphire or low-...

  1. E-Print Network 3.0 - arsenide single crystals Sample Search...

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

    Technion, Israel Institute of Technology Collection: Engineering ; Materials Science 73 Tunable narrow-bandwidth source of THz radiation based on frequency down-conversion in...

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

    E-Print Network [OSTI]

    Fossum, Eric R.

    susceptible to radiation and hot carrier damage than are MaS-based structures. This should result in increased;among these has been the construction of optical emitters such as LEDs and lasers, since efficient

  3. Building Stones

    E-Print Network [OSTI]

    2012-01-01T23:59:59.000Z

    known as “burnt gypsum” or “plaster of Paris. ” When mixedsolid material. Such “gypsum plaster” was produced from lateand painted. Gypsum plaster was also sometimes employed as a

  4. Micro-cooler enhancements by barrier interface analysis

    SciTech Connect (OSTI)

    Stephen, A.; Dunn, G. M. [Department of Physics, University of Aberdeen, King's College, AB24 3UE Aberdeen (United Kingdom)] [Department of Physics, University of Aberdeen, King's College, AB24 3UE Aberdeen (United Kingdom); Glover, J.; Oxley, C. H. [Department of Engineering, De Montfort University, Gateway, LE1 9BH Leicester (United Kingdom)] [Department of Engineering, De Montfort University, Gateway, LE1 9BH Leicester (United Kingdom); Bajo, M. Montes; Kuball, M. [Center for Device Thermography and Reliability, H. H. Wills Physics Laboratory, University of Bristol, BS8 1TL Bristol (United Kingdom)] [Center for Device Thermography and Reliability, H. H. Wills Physics Laboratory, University of Bristol, BS8 1TL Bristol (United Kingdom); Cumming, D. R. S.; Khalid, A. [School of Engineering, University of Glasgow, Rankine Building, G12 8LT Glasgow (United Kingdom)] [School of Engineering, University of Glasgow, Rankine Building, G12 8LT Glasgow (United Kingdom)

    2014-02-15T23:59:59.000Z

    A novel gallium arsenide (GaAs) based micro-cooler design, previously analysed both experimentally and by an analytical Heat Transfer (HT) model, has been simulated using a self-consistent Ensemble Monte Carlo (EMC) model for a more in depth analysis of the thermionic cooling in the device. The best fit to the experimental data was found and was used in conjunction with the HT model to estimate the cooler-contact resistance. The cooling results from EMC indicated that the cooling power of the device is highly dependent on the charge distribution across the leading interface. Alteration of this charge distribution via interface extensions on the nanometre scale has shown to produce significant changes in cooler performance.

  5. X-ray induced optical reflectivity

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

    Durbin, Stephen M.

    2012-01-01T23:59:59.000Z

    The change in optical reflectivity induced by intense x-ray pulses can now be used to study ultrafast many body responses in solids in the femtosecond time domain. X-ray absorption creates photoelectrons and core level holes subsequently filled by Auger or fluorescence processes, and these excitations ultimately add conduction and valence band carriers that perturb optical reflectivity.Optical absorption associated with band filling and band gap narrowing is shown to explain the basic features found in recent measurements on an insulator (silicon nitride, Si3N4), a semiconductor(gallium arsenide,GaAs), and a metal (gold,Au), obtained with ?100 fs x-ray pulses at 500-2000 eV and probed with 800 nm laser pulses. In particular GaAs exhibits an abrupt drop in reflectivity, persisting only for a time comparable to the x-ray excitation pulse duration, consistent with prompt band gap narrowing.

  6. High-efficiency solar cell and method for fabrication

    DOE Patents [OSTI]

    Hou, Hong Q. (Albuquerque, NM); Reinhardt, Kitt C. (Albuquerque, NM)

    1999-01-01T23:59:59.000Z

    A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD).

  7. High-efficiency solar cell and method for fabrication

    DOE Patents [OSTI]

    Hou, H.Q.; Reinhardt, K.C.

    1999-08-31T23:59:59.000Z

    A high-efficiency 3- or 4-junction solar cell is disclosed with a theoretical AM0 energy conversion efficiency of about 40%. The solar cell includes p-n junctions formed from indium gallium arsenide nitride (InGaAsN), gallium arsenide (GaAs) and indium gallium aluminum phosphide (InGaAlP) separated by n-p tunnel junctions. An optional germanium (Ge) p-n junction can be formed in the substrate upon which the other p-n junctions are grown. The bandgap energies for each p-n junction are tailored to provide substantially equal short-circuit currents for each p-n junction, thereby eliminating current bottlenecks and improving the overall energy conversion efficiency of the solar cell. Additionally, the use of an InGaAsN p-n junction overcomes super-bandgap energy losses that are present in conventional multi-junction solar cells. A method is also disclosed for fabricating the high-efficiency 3- or 4-junction solar cell by metal-organic chemical vapor deposition (MOCVD). 4 figs.

  8. 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)

    2013-01-01T23:59:59.000Z

    ??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… (more)

  9. Endolithic cyanobacteria in soil gypsum: Occurrences in Atacama (Chile), Mojave (United States), and Al-Jafr Basin (Jordan) Deserts

    E-Print Network [OSTI]

    Ahmad, Sajjad

    ), and Al-Jafr Basin (Jordan) Deserts Hailiang Dong,1 Jason A. Rech,1 Hongchen Jiang,1 Henry Sun,2, United States, and Al-Jafr Basin, Jordan, revealed endolithic cyanobacteria communities just below (United States), and Al-Jafr Basin (Jordan) Deserts, J. Geophys. Res., 112, G02030, doi:10.1029/2006JG

  10. 3D geological modelling at urban scale and mapping of ground movement susceptibility from gypsum dissolution: the Paris example (France)

    E-Print Network [OSTI]

    Boyer, Edmond

    , the Inspection Générale des Carrières (IGC; General Inspectorate of Quarries) has the task of managing the risks

  11. 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)

    2013-01-01T23:59:59.000Z

    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 ...

  12. Journal of Engineering Physics and Thermophysics, VoL 71, No..5, 1998 SIMULATION OF A GALLIUM ARSENIDE RUNNING

    E-Print Network [OSTI]

    Harilal, S. S.

    a single monolithic circuit are the main tendencies in the development of superhigh-frequency solid-GaAs-type semiconductors with transport of electrons between valleys [3 ] along with works in the field of creating HHT this constitutes the subject matter of this work. Model and Basic Relations. As was shown in a number of our works

  13. Bismuth in gallium arsenide: Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys

    SciTech Connect (OSTI)

    Reshak, Ali Hussain, E-mail: maalidph@yahoo.co.uk [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Kamarudin, H. [School of Material Engineering, Malaysia University of Perlis, P.O Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Auluck, S. [National Physical Laboratory Dr. KS Krishnan Marg, New Delhi 110012 (India); Kityk, I.V. [Electrical Engineering Department, Technological University of Czestochowa, Al. Armii Krajowej 17/19, Czestochowa (Poland)

    2012-02-15T23:59:59.000Z

    The structural and electronic properties of cubic GaAs{sub 1-x}Bi{sub x} alloys with bismuth concentration 0.0, 0.25, 0.50, 0.75 and 1.0 are studied using the 'special quasi-random structures' (SQS) approach of Zunger along with the generalized gradient approximation (GGA) and the Engel-Vosko generalized gradient approximation (EV-GGA). The lattice constant, bulk modulus, derivative of bulk modulus and energy gap vary with bismuth concentration nonlinearly. The present calculations show that the band gap decreases substantially with increasing bismuth concentration and that spin-orbit coupling influences the nature of bonding at high Bi concentrations. - Graphical abstract: Bowing effect of spin-orbit split-off band values versus Bi content with and without spin-orbit coupling for GaAs{sub 1-x}Bi{sub x} (at x=0.25, 0.50 and 0.75). Calculations are done with GGA. Highlights: Black-Right-Pointing-Pointer Structural and electronic properties of GaAs{sub 1-x}Bi{sub x} alloys were studied. Black-Right-Pointing-Pointer We present results of lattice constant, energy gap, bulk modulus and derivative. Black-Right-Pointing-Pointer The band gap decreases substantially with increasing Bi concentration. Black-Right-Pointing-Pointer Calculations of the density of states and charge densities are also presented. Black-Right-Pointing-Pointer We have performed calculations without and with spin-orbit coupling.

  14. Formation of Porous Layers by Electrochemical Etching of Germanium and Gallium Arsenide for Cleave Engineered Layer Transfer (CELT) Application in High Efficiency Multi-Junction Solar Cells

    E-Print Network [OSTI]

    Fong, David Michael

    2012-01-01T23:59:59.000Z

    film photovoltaics [1]. This roughly doubling of efficiencyMJ photovoltaics. MJ solar cells achieve higher efficiencies

  15. Formation of Porous Layers by Electrochemical Etching of Germanium and Gallium Arsenide for Cleave Engineered Layer Transfer (CELT) Application in High Efficiency Multi-Junction Solar Cells

    E-Print Network [OSTI]

    Fong, David Michael

    2012-01-01T23:59:59.000Z

    III! V Multijunction Solar Cells,” (2003). J. F. Geisz, etEfficiency Multi-Junction Solar Cells A thesis submitted inEfficiency Multi-Junction Solar Cells By David Michael Fong

  16. Simplified Numerical Description of Latent Storage Characteristics for Phase Change Wallboard

    E-Print Network [OSTI]

    Fuestel, H.E.

    2011-01-01T23:59:59.000Z

    implemented in gypsum board, plaster or other wall-coveringimplemented in gypsum board, plaster or other wall-coveringbillion square meters of plaster board produced annually in

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

    E-Print Network [OSTI]

    Hisaka, Takayuki

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

  18. Modifications du travail de sortie des surfaces clives de GaAs, lies au refroidissement

    E-Print Network [OSTI]

    Boyer, Edmond

    les positions energetiques des etats de surface. Cette idee a ete reprise et developpee par L. K experimentaux ne posent pas de probleme majeur [6], 1'exp6rimentation, delicate, conduit a se poser la question

  19. Fourier spectroscopy of individual nitrogen impurity centers in GaAs

    SciTech Connect (OSTI)

    Ikezawa, Michio [PRESTO-JST, JST, Kawaguchi, Japan and Institute of Physics, University of Tsukuba, Tsukuba (Japan); Zhang, Liao; Mori, Tatsuya; Masumoto, Yasuaki [Institute of Physics, University of Tsukuba, Tsukuba (Japan); Sakuma, Yoshiki; Sakoda, Kazuaki [National Institute for Materials Science, Tsukuba (Japan)

    2013-12-04T23:59:59.000Z

    We report on the measurement of the exciton homogeneous linewidth in nitrogen impurity centers in GaAs:N. Fourier spectroscopy on a single center revealed a long coherence time over 300 ps at low temperature. The narrowest linewidth obtained at liquid helium temperature is 3.5 ?eV, which is comparable with that of semiconductor quantum dots. The linewidth increases with increasing temperature, showing a thermally activated behavior with activation energies of 2?5 meV.

  20. E-Print Network 3.0 - activated si-gaas high-voltage Sample Search...

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

    Polytechnique, Centre de mathmatiques Collection: Mathematics 48 1 of 5 Copyright 2007 Tesla Motors Updated: December 19, 2007 The Tesla Roadster Battery System Summary: to...

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

    E-Print Network [OSTI]

    Adeyemi, Oluwafemi Ibukunoluwa

    2007-04-25T23:59:59.000Z

    for Noise Analysis of Open-Loop Common-Gate TIA……………………………………………………………... 25 Fig. 3.6. Feedback TIA………………………………………………….. 26 Fig. 3.7. Feedback TIA Characteristics…………………………………. 28 Fig. 3.8. HEMT and HBT Feedback TIAs 30 Fig. 3.9. Photodiode.../ driver Repeaters Optical Fiber Several miles Optical Fiber Laser Diode Photodiode Preamplifier/ Transimpedance Amplifier Automatic Gain Control Digital Information Digital Information Receiver Fig. 1.1. Illustration of a Digital Fiber...

  2. Weak localization of dilute 2D electrons in undoped GaAs heterostructures.

    SciTech Connect (OSTI)

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

    2004-07-01T23:59:59.000Z

    The temperature dependence of the resistivity and magnetoresistance of dilute 2D electrons are reported. The temperature dependence of the resistivity can be qualitatively described through phonon and ionized impurity scattering. While the temperature dependence indicates no ln(T) increase in the resistance, a sharp negative magnetoresistance feature is observed at small magnetic fields. This is shown to arise from weak localization. At very low density, we believe weak localization is still present, but cannot separate it from other effects that cause magnetoresistance in the semi-classical regime.

  3. E-Print Network 3.0 - adsorbate covered gaas1 Sample Search Results

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

    ; Physics ; Materials Science 82 Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky* Summary: that the...

  4. Excitation-Dependent Recombination and Diffusion Near an Isolated Dislocation in GaAs

    SciTech Connect (OSTI)

    Gfroerer, T. H.; Crowley, C. M.; Read, C. M.; Wanlass, M. W.

    2012-06-01T23:59:59.000Z

    In low-magnification, plan-view photoluminescence images of a nominally lattice-matched, undoped GaAs/GaInP heterostructure, we observe a random distribution of isolated dark spots. We attribute the dark spots to crystal dislocations, where nonradiative recombination is augmented by transitions utilizing defect-related energy levels between the conduction and valence bands. We note that, when the laser excitation intensity is reduced, the darkened regions expand. At lower excitation, the density of photogenerated electrons and holes is reduced, and they are more likely to reach the defective region before encountering a partner for radiative recombination. When we model the behavior with a simulation that allows for Laplacian diffusion and defect-related recombination only through mid-bandgap energy levels, we do not obtain good agreement between experimental and simulated images. But if we allow for an arbitrary distribution of defect levels, such that the occupation of the levels and bands can change independently, we have more flexibility for fitting the density-dependent recombination rates. The more sophisticated model produces results that are more consistent with experimental images.

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

    SciTech Connect (OSTI)

    Benner, J.P.

    1985-05-01T23:59:59.000Z

    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.

  6. Copper Doped GaAs Infrared Filter for the 8-13 m Atmospheric Window

    E-Print Network [OSTI]

    Peale, Robert E.

    regions of interest, such as atmospheric transmission windows. Filters exclude solar or thermal photonsCdTe is typically melt grown in a high temperature furnace. All three elements in this alloy are toxic. Stability

  7. 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:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsruc DocumentationP-Series to UserProduct:Directives Templates8. U.S.Donald R. Baer

  8. Surface Science Analysis of GaAs Photocathodes Following Sustained Electron

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

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security AdministrationcontrollerNanocrystalline GalliumSuppression of conductivity inBatteriesonBeam Delivery. |

  9. GaAs on Si,,111...--crystal shape and strain relaxation in nanoscale patterned growth

    E-Print Network [OSTI]

    New Mexico, University of

    . R. Dawson, and S. R. J. Brueck Center for High Technology Materials and Department of Electrical and Computer Engineering, University of New Mexico, 1313 Goddard, SE, Albuquerque, New Mexico 87106 Y.-B. Jiang Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87103 Received

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

    SciTech Connect (OSTI)

    Hubbard, Seth

    2012-09-12T23:59:59.000Z

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

  11. E-Print Network 3.0 - aluminium gallium indium Sample Search...

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

    An advanced diffusion model to identify emergent research issues: the case of optoelectronic devices Summary: Aluminium arsenides Ge-Si alloys Avalanche photodiodes Indium...

  12. The role of screening of the electron-phonon interaction in relaxation of photoexcited electron-hole plasma in semiconductors

    SciTech Connect (OSTI)

    Kumekov, S. E. [Kazakh National Technical University (Kazakhstan)], E-mail: skumekov@mail.ru

    2008-08-15T23:59:59.000Z

    The role of screening of the interaction of the electron-hole plasma with optical phonons is analytically evaluated by the example of gallium arsenide.

  13. Accomplishments | Department of Energy

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

    water. (NREL) 1991 Gallium Indium PhosphideGallium Arsenide Tandem Solar Cell: A light, highly efficient solar cell that has become the world's standard for powering...

  14. Alta Devices Develops World Record Setting Thin-Film Solar Cell

    Office of Energy Efficiency and Renewable Energy (EERE)

    EERE supported the development of Alta Devices' thin film Gallium Arsenide photovoltaic technology that set a world record for conversion efficiency.

  15. Inelastic Neutron Scattering Study of a Nonmagnetic Collapsed Tetragonal Phase in Nonsuperconducting CaFe2As2: Evidence of the Impact of Spin Fluctuations on Superconductivity in the Iron-Arsenide Compounds

    SciTech Connect (OSTI)

    Soh, Jing-Han [Ames Laboratory; Tucker, Ggregory S. [Ames Laboratory; Pratt, Daniel K. [Ames Laboratory; Abernathy, D. L. [Oak Ridge National Laboratory; Stone, M. B. [Oak Ridge National Laboratory; Ran, Sheng [Ames Laboratory; Budko, Sergey L. [Ames Laboratory; Canfield, Paul C. [Ames Laboratory; Kreyssig, Andreas [Ames Laboratory; McQueeney, Robert J. [Ames Laboratory; Goldman, Alan I. [Ames Laboratory

    2013-11-27T23:59:59.000Z

    The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the nonsuperconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is nonmagnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

  16. Inelastic neutron scattering study of a nonmagnetic collapsed tetragonal phase of CaFe2As2: Evidence of the impact of spin fluctuations on superconductivity in the iron-arsenide compounds.

    SciTech Connect (OSTI)

    Soh, Jing Han [ORNL] [ORNL; Tucker, G. S. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; Pratt, Daniel K [ORNL] [ORNL; Abernathy, Douglas L [ORNL] [ORNL; Stone, Matthew B [ORNL] [ORNL; Ran, S. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; Budko, S L [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; Canfield, P. C. [Ames Laboratory] [Ames Laboratory; Kreyssig, A. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University; McQueeney, R. J. [Ames Laboratory] [Ames Laboratory; Goldman, A. I. [Ames Laboratory and Iowa State University] [Ames Laboratory and Iowa State University

    2013-01-01T23:59:59.000Z

    The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the non-superconducting collapsed tetragonal phase of CaFe2As2 via inelas- tic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetrag- onal phase of CaFe2As2 is non-magnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

  17. Thermal Performance of Phase Change Wallboard for Residential Cooling Application

    E-Print Network [OSTI]

    Feustel, H.E.

    2011-01-01T23:59:59.000Z

    implemented in gypsum board, plaster or other wall-coveringimbedded in gypsum board, plaster or other wall-covering7 billion square meters of plaster board are being produced

  18. Accumulation and replacement of exchangeable sodium in soils of Southeast Texas under turfgrass and its effect on soil infiltration rate

    E-Print Network [OSTI]

    Aydemir, Salih

    2012-06-07T23:59:59.000Z

    in soils of this area. This study assessed the degree of Na accumulation on cation exchange sites as affected by gypsum treatments in soils that support turfgrass (bermudagrass) and the response of soil infiltration rate to different rates of gypsum...

  19. Effective masses for small nitrogen concentrations in InGaAsN alloys on GaAs

    SciTech Connect (OSTI)

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

    2000-05-11T23:59:59.000Z

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

  20. SIMULATIONS OF A HIGH POWER 4H-SiC VJFET AND ITS GaAs COUNTERPART

    E-Print Network [OSTI]

    Myles, Charles W.

    of the two devices. The two-dimensional simulations were carried out using the ATLAS simulator from Silvaco

  1. Perturbation of Au-assisted planar GaAs nanowire growth by p-type dopant impurities

    E-Print Network [OSTI]

    Li, Xiuling

    , Chen Zhang, Parsian K. Mohseni, Seth A. Fortuna, Jian-Guo Wen, James J. Coleman, and Xiuling Li-up assembly of large-area nanowire resonator arrays," Nat. Nanotechnol. 3(2), 88­92 (2008). 5. S. A. Fortuna Device Lett. 30(6), 593­595 (2009). 6. R. Dowdy, D. A. Walko, S. A. Fortuna, and X. Li, "Realization

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

    E-Print Network [OSTI]

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

    1997-01-01T23:59:59.000Z

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

  3. Effect of quantum dot position and background doping on the performance of quantum dot enhanced GaAs solar cells

    SciTech Connect (OSTI)

    Driscoll, Kristina, E-mail: kmdsps@rit.edu; Bennett, Mitchell F.; Polly, Stephen J.; Forbes, David V.; Hubbard, Seth M., E-mail: smhsps@rit.edu [NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, New York (United States)

    2014-01-13T23:59:59.000Z

    The effect of the position of InAs quantum dots (QD) within the intrinsic region of pin-GaAs solar cells is reported. Simulations suggest placing the QDs in regions of reduced recombination enables a recovery of open-circuit voltage (V{sub OC}). Devices with the QDs placed in the center and near the doped regions of a pin-GaAs solar cell were experimentally investigated. While the V{sub OC} of the emitter-shifted device was degraded, the center and base-shifted devices exhibited V{sub OC} comparable to the baseline structure. This asymmetry is attributed to background doping which modifies the recombination profile and must be considered when optimizing QD placement.

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

    E-Print Network [OSTI]

    Rockett, Angus

    . INTRODUCTION The Cu(In, Ga)Se2 CIGS absorber layer in a recent record-efficiency CIGS solar cell1 has a 220.13 Commercially supplied ``epi-ready'' liquid- encapsulated Czo

  5. Growth Mechanism and Electronic Structure of Zn3P2 on the Ga-Rich GaAs(001) Surface

    E-Print Network [OSTI]

    Atwater, Harry

    as well as the potential for low-cost, thin-film fabrication make Zn3P2 a promising active material Zn3P2 films on III-V substrates unlocks a promising pathway toward high-efficiency, earth-abundant photovoltaic devices fabricated on reusable, single-crystal templates. The detailed chemical, structural

  6. Noncontact deep level photo-thermal spectroscopy: Technique and application to semi-insulating GaAs Wafers

    E-Print Network [OSTI]

    Mandelis, Andreas

    to high resistivity materials, since the Debye-Huckel length is too large several milli- meters for semi materials. In DLPTS, the thermal recovery of carriers after excita- tion is monitored by a subNoncontact deep level photo-thermal spectroscopy: Technique and application to semi-insulating Ga

  7. MOUSSES MINERALES A PERFORMANCES OPTIMISEES

    E-Print Network [OSTI]

    Boyer, Edmond

    of these gypsum foams are then assessed and compared to the ones obtained for cellular and hemp concrete. Physical

  8. Photo: D. Stevenson and C. Conway/Beckman Institute/University of Illinois An inorganic LED display printed on a flexible substrate bends without breaking

    E-Print Network [OSTI]

    Rogers, John A.

    by the Ford Motor Co., which envisions many possible automotive applications for thin, flexible lighting this atop a layer of aluminum arsenide which itself coated a gallium arsenide substrate. Using a combination, such displays would be almost completely transparent--and well suited for another automotive need: inexpensive

  9. This article has been accepted for inclusion in a future issue of this journal. Content is final as presented, with the exception of pagination. IEEE JOURNAL OF PHOTOVOLTAICS 1

    E-Print Network [OSTI]

    Atwater, Harry

    as presented, with the exception of pagination. IEEE JOURNAL OF PHOTOVOLTAICS 1 Gallium Arsenide Solar Cell--Gallium arsenide, nanospheres, photovoltaic systems, whispering gallery modes (WGMs). I. INTRODUCTION THE route as the active layer is thinned [2]. Thin-film photovoltaics offer the possibility to significantly reduce

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

    E-Print Network [OSTI]

    IPA is chosen as the oxygen source for the ALD in the MOCVD. Second, IPA will not react precursor pulse time. b Dependence of ALD Al2O3 growth rate on temperature. The pulse time for TMA and IPA

  11. Ralisation et caractrisation d'un transistor effet de champ JFET au GaAs en vue de son intgration avec une photodiode

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    intégration avec une photodiode M. T. Belaroussi, F. Therez et R. Alcubilla (*) Laboratoire d'Automatique et d étendus à la fabrication du circuit intégré GaAlAs-GaAs associant une photodiode à un TEC. Abstract. 2014AlAs-GaAs monolithic integration of a photodiode and FET. Revue Phys. Appl. 22 (1987) 77-82 JANVIER 1987

  12. 60 GHz Harmonic Optoelectronic Up-Conversion Using an InAlAs/InGaAs Metamorphic High-Electron-Mobility Transistor on a GaAs Substrate

    E-Print Network [OSTI]

    Choi, Woo-Young

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

  13. Growth of alternating (1OO)/(lll )-oriented II-VI regions for quasi-phase-matched nonlinear optical devices on GaAs substrates

    E-Print Network [OSTI]

    Fejer, Martin M.

    ferroelectrics such as lithium nio- bate and potassium titanyl phosphate. Efficient operation is possible) nonlinear interactions. II-VI semiconductors, with transparency from the far in- frared to the visible phasematched interactions.' A powerful alternative technique, QPM, re- quires periodic patterning of the sign

  14. A quantitative conduction model for a low-resistance nonalloyed ohmic contact structure utilizing low-temperature-grown GaAs

    E-Print Network [OSTI]

    Woodall, Jerry M.

    A quantitative conduction model for a low-resistance nonalloyed ohmic contact structure utilizing properties of this material. The specific contact resistance is then calculated using an analytic expression for tunneling conduction through an equivalent uniformly doped Schottky barrier. The model has been used to fit

  15. Complementary GaAs Technology for High-Speed VLSI Circuits Richard B. Brown, Bruce Bernhardt*, Mike LaMacchia**, Jon Abrokwah***, Phiroze N. Parakh,

    E-Print Network [OSTI]

    Mudge, Trevor

    , Claude R. Gauthier, David Foster**, Brian Crawforth**, Timothy McQuire**, Karem Sakallah, Ronald J. Lomax

  16. Complementary GaAs Technology for HighSpeed VLSI Circuits Richard B. Brown, Bruce Bernhardt*, Mike LaMacchia**, Jon Abrokwah***, Phiroze N. Parakh,

    E-Print Network [OSTI]

    Mudge, Trevor

    , Claude R. Gauthier, David Foster**, Brian Crawforth**, Timothy McQuire**, Karem Sakallah, Ronald J. Lomax

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

    E-Print Network [OSTI]

    Southern California, University of

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

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

    E-Print Network [OSTI]

    Beaton, D. 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 ...

  19. Stochastic versus Robust Optimization for a Transportation Problem

    E-Print Network [OSTI]

    Francesca Maggioni

    2015-03-05T23:59:59.000Z

    Mar 5, 2015 ... Abstract: In this paper we consider a transportation problem under uncertainty related to gypsum replenishment for a cement producer.

  20. Irrigation Water Quality Salinity Management

    E-Print Network [OSTI]

    Na2SO4 Moderate to large Calcium chloride CaCl2 Moderate Calcium sulfate (gypsum) CaSO4 2H2O Moderate

  1. The effect of inclusions in brittle material

    E-Print Network [OSTI]

    Janeiro, Raymond Pinho

    2009-01-01T23:59:59.000Z

    This thesis experimentally investigates the cracking behavior of brittle heterogeneous materials. Unconfined, uniaxial compression tests are conducted on prismatic gypsum specimens containing either one, or two, inclusions. ...

  2. Building Stones

    E-Print Network [OSTI]

    2012-01-01T23:59:59.000Z

    Ancient Egyptian limestone quarries: A petrological survey.pp. 195 - 212. 2001 Ancient quarries near Amarna. Egyptian36 - 38. 2010 An early Roman quarry for anhydrite and gypsum

  3. Model Code for the Control of Residential HVAC Distribution System Leakage and HVAC-Induced Building Leakage

    E-Print Network [OSTI]

    Wemhoff, P.

    1990-01-01T23:59:59.000Z

    , Underwriters Laboratories, Inc., the Air Conditioning Contractors Of America, the Thermal Insulation Manufacturers Association, the National Fire Protection Association, and the Gypsum Association....

  4. GALLIUM--2002 29.1 References that include a section mark () are found in the Internet

    E-Print Network [OSTI]

    consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic devices application for gallium, with 46% of total consumption. Optoelectronic devices accounted for 42% of domestic

  5. doi: 10.1149/1.2108814 1986, Volume 133, Issue 6, Pages 1176-1179.J. Electrochem. Soc.

    E-Print Network [OSTI]

    Woodall, Jerry M.

    -Si/GaAs interfaces have been prepared by depositing hydrogenated amorphous Si (a-Si:H) onto GaAs in a silane plasma is the case for other lattice mismatched GaAs heterojunctions and most

  6. Photovoltaic Single-Crystalline, Thin-Film Cell Basics | Department...

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

    been developed for light-emitting diodes, lasers, and other electronic devices that use light. GaAs solar cells offer several benefits: The GaAs bandgap is 1.43 eV-nearly ideal...

  7. E-Print Network 3.0 - algainp light-emitting diodes Sample Search...

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

    by sequentially adding components of different types. Six hundred AlGaInP GaAs light- emitting diode segments... of 600 AlGaInP GaAs light-emitting diodes (LEDs) onto device...

  8. VOLUME 76, NUMBER 8 P H Y S I C A L R E V I E W L E T T E R S 19 FEBRUARY 1996 Spin Splitting of Single 0D Impurity States in Semiconductor Heterostructure Quantum Wells

    E-Print Network [OSTI]

    Reed, Mark

    cm23 Si doped GaAs contact, a 15 nm undoped GaAs spacer layer, a 8.5 nm undoped Al0.27Ga0.73As bottom GaAs spacer layer, and a 1.8 3 1018 cm23 Si doped GaAs top contact. Square mesas with lateral dimensions from 2 to 64 mm are fabricated using standard photolithography techniques. Two terminal I V

  9. Demonstration of InAsBi photoresponse beyond 3.5??m

    SciTech Connect (OSTI)

    Sandall, I. C., E-mail: I.sandall@sheffield.ac.uk; Bastiman, F.; White, B.; Richards, R.; Mendes, D.; David, J. P. R.; Tan, C. H. [Department of Electronic and Electrical Engineering, The University of Sheffield, Sir Frederick Mappin Building, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2014-04-28T23:59:59.000Z

    An Indium Arsenide Bismide photodiode has been grown, fabricated, and characterized to evaluate its performance in the Mid Wave Infrared region of the spectrum. Spectral response from the diode has been obtained up to a diode temperature of 225?K. At this temperature, the diode has a cut off wavelength of 3.95 ?m, compared to 3.41 ?m in a reference Indium Arsenide diode, indicating that Bismuth has been incorporated to reduce the band gap of Indium Arsenide by 75?meV. Similar band gap reduction was deduced from the cut off wavelength comparison at 77?K. From the dark current data, shunt resistance values of 8 and 39 ? at temperatures of 77 and 290?K, respectively, were obtained in our photodiode.

  10. Low dimensional GaAs/air vertical microcavity lasers

    SciTech Connect (OSTI)

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

    2014-02-24T23:59:59.000Z

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

  11. Clean process to destroy arsenic-containing organic compounds with recovery of arsenic

    DOE Patents [OSTI]

    Upadhye, R.S.; Wang, F.T.

    1996-08-13T23:59:59.000Z

    A reduction method is provided for the treatment of arsenic-containing organic compounds with simultaneous recovery of pure arsenic. Arsenic-containing organic compounds include pesticides, herbicides, and chemical warfare agents such as Lewisite. The arsenic-containing compound is decomposed using a reducing agent. Arsine gas may be formed directly by using a hydrogen-rich reducing agent, or a metal arsenide may be formed using a pure metal reducing agent. In the latter case, the arsenide is reacted with an acid to form arsine gas. In either case, the arsine gas is then reduced to elemental arsenic. 1 fig.

  12. Indirect excitons in GaAs coupled quantum wells : development of optoelectronic logic devices and trapping potentials, and studies of low temperature phenomena in a bosonic condensed matter system

    E-Print Network [OSTI]

    High, Alexander Arthur; High, Alexander Arthur

    2012-01-01T23:59:59.000Z

    the develop- ment of optoelectronics but also in the studiesof exciton based optoelectronics, that of scalability, willin exciton-based optoelectronics have been made. This

  13. VOLUME 78, NUMBER 2 P H Y S I C A L R E V I E W L E T T E R S 13 JANUARY 1997 Observation of Coherently Controlled Photocurrent in Unbiased, Bulk GaAs

    E-Print Network [OSTI]

    Van Driel, Henry M.

    -charge fields and enhanced second-harmonic generation in optical fibers [7]. Although the results in LT-GaAs are measured for injected carrier densities as low as 1014 cm23 and for peak irradiances.50.Ar, 42.65.­k The idea of controlling optical, physical, and chemical processes in matter using

  14. Summary Abstract: The MBE growth of GaAs free of oval defects G. D. Pettit, J. M. Woodall, S. L. Wright, P. D. Kirchner, and J. L. Freeouf

    E-Print Network [OSTI]

    Woodall, Jerry M.

    . Wright, P. D. Kirchner, and J. L. Freeouf IBM Thomas J. Watson Research Center, Yorktown Heights, New

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

    2008-03-15T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    Lin, Kai Hsuan

    1994-01-01T23:59:59.000Z

    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. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research

    E-Print Network [OSTI]

    Paytan, Adina

    of Geology and Environmental Geosciences, Northern Illinois University, Davis Hall 312, DeKalb, IL 60115, USA Chetumal, Quintana Roo to Campeche, Campeche. The presence of gypsum quarries in the area is also

  18. Continuing Education and Training Needs of the Southern Forest Industry.

    E-Print Network [OSTI]

    Thomas, John K.; Albrecht, Don E.; Lee, J. Charles; Klinoff, Roger

    1985-01-01T23:59:59.000Z

    and Paper Champion International Kirby Forest Industries Louisiana -Pacific Owens Illinois Temple EasTex Bear Island Paper Chesapeake Owens Illinois Union Camp United States Gypsum V irginia Fibr~ Westvaco CSX Resources Westvaco 13 14...

  19. Effects of tunneling on groundwater flow and swelling of clay-sulfate rocks

    E-Print Network [OSTI]

    Butscher, Christoph

    [1] Swelling of clay-sulfate rocks is a major threat in tunneling. It is triggered by the transformation of the sulfate mineral anhydrite into gypsum as a result of water inflow in anhydrite-containing layers after tunnel ...

  20. 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.

    2009-05-01T23:59:59.000Z

    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.

  1. Building Stones

    E-Print Network [OSTI]

    2012-01-01T23:59:59.000Z

    anhydrite and gypsum near Wadi el-Anba’ut, Red Sea coast,West Bank (ED:3; small) Wadi Rayan Formation of the MokattamNK & Pt-R? ; medium) 21. in Wadi Sheikh Yasin east of Zawyet

  2. A New Concept in Dryer Control

    E-Print Network [OSTI]

    Robinson, J. W.

    , lumber, fiberboard, gypsum board, crumb rubber, etc. In addition, such dryer types as Rotary Drum, Suspension, Flash, Through, Spray, Oven, Tray, Lime Kilns, etc., should be amenable to control utilizing this model. Moreover, it should apply to most thin...

  3. Journal of California and Great Basin Anthropology | Vol. 32, No. 1 (2012) | pp. 4764 Chemical Composition, Mineralogy,

    E-Print Network [OSTI]

    2012-01-01T23:59:59.000Z

    Composition, Mineralogy, and Physical Structure of Pigments on Arrow and Dart Fragments from Gypsum Cave), and electron microprobe (EM) to determine their chemical composition, mineralogy, and physical structure pigments. Although variation in composition and mineralogy suggests some degree of experimentation

  4. Urban Form Energy Use and Emissions in China: Preliminary Findings and Model Proof of Concept

    E-Print Network [OSTI]

    Aden, Nathaniel

    2011-01-01T23:59:59.000Z

    producing building materials, but it does not include upstream requirements of energyenergy required for producing the water, limestone, sandstone, gypsum, and clay typically used for cement production. The building

  5. E-Print Network 3.0 - acute low-level microwave Sample Search...

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

    of California at San Diego Collection: Engineering 5 2picosecond, GaAs photodiode optoelectronic circuit for optical correlation applications Summary: diode that serves as the...

  6. E-Print Network 3.0 - absorption coefficient based Sample Search...

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

    67 Optical nonlinearity in low-temperature-grown GaAs: Microscopic limitations and optimization strategies Summary: is the absorption coefficient, d the physical thickness of the...

  7. 2070 OPTICS LETTERS / Vol. 29, No. 17 / September 1, 2004 400-photon-per-pulse ultrashort pulse autocorrelation

    E-Print Network [OSTI]

    Purdue University

    -photon absorption in silicon avalanche photodiodes,3 GaAs photomultiplier tubes,4 and InGaAsP laser diodes.5

  8. E-Print Network 3.0 - advanced technology large-aperture Sample...

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

    (Advanced Photonix). These diodes were chosen for two reasons. First... pulsed terahertz emitter, a large-aperture GaAs photoconductive switch, is carried out. It is...

  9. 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

  10. Simple intrinsic defects in InAs : numerical predictions.

    SciTech Connect (OSTI)

    Schultz, Peter Andrew

    2013-03-01T23:59:59.000Z

    This Report presents numerical tables summarizing properties of intrinsic defects in indium arsenide, InAs, as computed by density functional theory using semi-local density functionals, intended for use as reference tables for a defect physics package in device models.

  11. Nematic spin fluid in the tetragonal phase of BaFe2As2 Leland W. Harriger 1

    E-Print Network [OSTI]

    Hu, Jiangping

    of Sciences, Beijing 100190, China 3 ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot as the source of the pseudogap behavior observed in copper oxide superconductors17-19 . Furthermore of the lattice and magnetic transitions in iron arsenides, but will also determine the importance of electron

  12. Resonant Spin Excitation in the High Temperature Superconductor Ba0.6K0.4Fe2As2

    SciTech Connect (OSTI)

    Christianson, Andrew D [ORNL; Goremychkin, E. A. [ISIS Facility, Rutherford Appleton Laboratory; Osborn, R. [Argonne National Laboratory (ANL); Rosenkranz, Stephen [Argonne National Laboratory (ANL); Lumsden, Mark D [ORNL; Malliakas, C. [Northwestern University, Evanston; Todorov, L. [Northwestern University, Evanston; Claus, H. [Northwestern University, Evanston; Chung, D.Y. [Northwestern University, Evanston; Kanatzidis, M. [Northwestern University, Evanston; Bewley, Robert I. [ISIS Facility, Rutherford Appleton Laboratory; Guidi, T. [ISIS Facility, Rutherford Appleton Laboratory

    2008-01-01T23:59:59.000Z

    A new family of superconductors containing layers of iron arsenide has attracted considerable interest because of their high transition temperatures (T{sub c}), some of which are >50 K, and because of similarities with the high-{sub c} copper oxide superconductors. In both the iron arsenides and the copper oxides, superconductivity arises when an antiferromagnetically ordered phase has been suppressed by chemical doping. A universal feature of the copper oxide superconductors is the existence of a resonant magnetic excitation, localized in both energy and wavevector, within the superconducting phase. This resonance, which has also been observed in several heavy-fermion superconductors is predicted to occur when the sign of the superconducting energy gap takes opposite values on different parts of the Fermi surface, an unusual gap symmetry which implies that the electron pairing interaction is repulsive at short range. Angle-resolved photoelectron spectroscopy shows no evidence of gap anisotropy in the iron arsenides, but such measurements are insensitive to the phase of the gap on separate parts of the Fermi surface. Here we report inelastic neutron scattering observations of a magnetic resonance below T{sub c} in Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2}, a phase-sensitive measurement demonstrating that the superconducting energy gap has unconventional symmetry in the iron arsenide superconductors.

  13. Transition from Three-Dimensional Anisotropic Spin Excitations to Two-Dimensional Spin Excitations by Electron Doping the FeAs-Based BaFe1:96Ni0:04As2 Superconductor

    E-Print Network [OSTI]

    Hu, Jiangping

    by Electron Doping the FeAs-Based BaFe1:96Ni0:04As2 Superconductor Leland W. Harriger,1 Astrid Schneidewind,2 arsenides is important because high-transition temperature (high-Tc) superconductivity arises from electron optimal superconductivity [4­6], the gapped spin wave excitations were replaced by a gapless continuum

  14. Controls on the genesis of hydrothermal cobalt mineralization: insights from the mineralogy and geochemistry of the Bou Azzer deposits, Morocco

    E-Print Network [OSTI]

    Controls on the genesis of hydrothermal cobalt mineralization: insights from the mineralogy,Ni,Fe) arsenides and sulpharsenides, with accessory sulphides and gold in a quartz-carbonate gangue. The ore-Ni-Fe, avec des quantités mineures de sulphures et de l'or dans une gangue de quartz- carbonate. Les minerais

  15. Density functional study of the structure, thermodynamics and electronic properties of This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Pandey, Ravi

    arsenide (CdGeAs2) due to its suitability for non-linear optical applications in the infrared region radiation damage [10], magnetic resonance [11] and thermal admittance spectroscopy [12] techniques. The bulk. It has the highest non-linear optical coefficient, 236 pm V-1 , known for a phase-matchable compound

  16. innovati nNREL Scientists Spurred the Success of Multijunction Solar Cells

    E-Print Network [OSTI]

    innovati nNREL Scientists Spurred the Success of Multijunction Solar Cells Before 1984, many a solar cell can convert into electricity. Olson thought the focus should change to finding materials-winning gallium indium phosphide/gallium arsenide tandem solar cell, which had achieved record efficiencies, con

  17. Preliminary materials assessment for the Satellite Power System (SPS)

    SciTech Connect (OSTI)

    Teeter, R.R.; Jamieson, W.M.

    1980-01-01T23:59:59.000Z

    Presently, there are two SPS reference design concepts (one using silicon solar cells; the other using gallium arsenide solar cells). A materials assessment of both systems was performed based on the materials lists set forth in the DOE/NASA SPS Reference System Report: Concept Development and Evaluation Program. This listing identified 22 materials (plus miscellaneous and organics) used in the SPS. Tracing the production processes for these 22 materials, a total demand for over 20 different bulk materials (copper, silicon, sulfuric acid, etc.) and nealy 30 raw materials (copper ore, sand, sulfur ore, etc.) was revealed. Assessment of these SPS material requirements produced a number of potential material supply problems. The more serious problems are those associated with the solar cell materials (gallium, gallium arsenide, sapphire, and solar grade silicon), and the graphite fiber required for the satellite structure and space construction facilities. In general, the gallium arsenide SPS option exhibits more serious problems than the silicon option, possibly because gallium arsenide technology is not as well developed as that for silicon. Results are presented and discussed in detail. (WHK)

  18. The relevance of contemporary bronze casting in Ubon, Thailand for understanding the archaeological record of the Bronze Age in Peninsular Southeast Asia

    E-Print Network [OSTI]

    Everly, Daniel Eugene

    2006-04-12T23:59:59.000Z

    ????????????........ 109 Bowl Furnace Construction????????????.. 109 Melting the Bronze?????????????........... 110 Pouring the Molten Bronze??????????........... 111 Removing the Bronze Product from the Clay Mould........... 112... arsenides) following the addition of the arsenic material to the molten copper with its subsequent diffusion into the copper due to the miscibility (blending) qualities of the two materials. ?Once the arsenates were exhausted in copper deposits...

  19. Friday, May 21, 2010 High-Performance Electronics without the High Price

    E-Print Network [OSTI]

    Rogers, John A.

    materials. Researchers have used the method to make high-performance image sensors, transistors, and solar exotic semiconductors brings down the cost of high- performance solar cells and microchips. By Katherine Bourzac Compared to silicon, semiconductors like gallium arsenide can be made into solar cells

  20. e! Science News Semiconductor manufacturing technique holds

    E-Print Network [OSTI]

    Rogers, John A.

    arsenide chips manufactured in multilayer stacks: light sensors, high-speed transistors and solar cellse! Science News Semiconductor manufacturing technique holds promise for solar energy Published semiconductor manufacturing method pioneered at the University of Illinois, the future of solar energy just got

  1. Initial stages of the autocatalytic oxidation of the InAs(0 0 1)-(4 2)/c(8 2) surface by molecular oxygen

    E-Print Network [OSTI]

    Kummel, Andrew C.

    by molecular oxygen Jonathon B. Clemens a , Sarah R. Bishop a , Darby L. Feldwinn a,1 , Ravi Droopad b,2 simulations Scanning tunneling microscopy Chemisorption Oxidation Indium arsenide Oxygen Semi conducting) surface by molecular oxygen (O2) were studied using scanning tunneling microscopy (STM) and density

  2. 256 NATURE PHYSICS | VOL 8 | APRIL 2012 | www.nature.com/naturephysics news & views

    E-Print Network [OSTI]

    Loss, Daniel

    resonances, such as the vibrational modes of a suspended beam. Now, Martin Gustafsson and colleagues, writing-state equivalent of ripples on a pond. In piezoelectric materials (such as the gallium arsenide slab used in a radiofrequency- tank circuit, one obtains a so-called radiofrequency SET5 -- an extremely sensitive and fast

  3. National Renewable Energy Laboratory

    E-Print Network [OSTI]

    Hydrogen-Production Technology Hydrogen offers great promise as a clean fuel in our nation's energy research and collaboration to improve the durability of photovoltaic cells for PEC hydrogen production-indium-phosphide/ gallium-arsenide) with an impressive 12.4% solar-to-hydrogen efficiency. Unfortunately, the tandem cell

  4. Method of making suspended thin-film semiconductor piezoelectric devices

    DOE Patents [OSTI]

    Casalnuovo, Stephen A. (Albuquerque, NM); Frye-Mason, Gregory C. (Cedar Crest, NM)

    2001-01-01T23:59:59.000Z

    A process for forming a very thin suspended layer of piezoelectric material of thickness less than 10 microns. The device is made from a combination of GaAs and AlGaAs layers to form either a sensor or an electronic filter. Onto a GaAs substrate is epitaxially deposited a thin (1-5 micron) sacrificial AlGaAs layer, followed by a thin GaAs top layer. In one embodiment the substrate is selectively etched away from below until the AlGaAs layer is reached. Then a second selective etch removes the sacrificial AlGaAs layer, that has acted here as an etch stop, leaving the thin suspended layer of piezoelectric GaAs. In another embodiment, a pattern of small openings is etched through the thin layer of GaAs on top of the device to expose the sacrificial AlGaAs layer. A second selective etch is done through these openings to remove the sacrificial AlGaAs layer, leaving the top GaAs layer suspended over the GaAs substrate. A novel etchant solution containing a surface tension reducing agent is utilized to remove the AlGaAs while preventing buildup of gas bubbles that would otherwise break the thin GaAs layer.

  5. 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.

    1204 IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 34, NO. 9, SEPTEMBER 1999 Breakdown in Millimeter-Wave Power InP HEMT's: A Comparison with GaAs PHEMT's J. A. del Alamo and M. H. Somerville Abstract's) deliver lower output power than GaAs pseudomorphic HEMT's (PHEMT's) throughout most of the millimeter

  6. GALLIUM--2000 30.1 By Deborah A. Kramer

    E-Print Network [OSTI]

    the largest application for gallium, with optoelectronic devices [mostly laser diodes and light-use application for gallium, with 63% of total consumption. Optoelectronic devices accounted for 32% of domestic% of the gallium consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic

  7. GALLIUM--1998 29.1 By Deborah A. Kramer

    E-Print Network [OSTI]

    's) were the largest application for gallium, with optoelectronic devices [mostly laser diodes and light-use application for gallium, with 52% of total consumption. Optoelectronic devices accounted for 45% of domestic% of the gallium consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic

  8. GALLIUM--2003 28.1 References that include a section mark () are found in the Internet

    E-Print Network [OSTI]

    in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic devices (LEDs, laser diodes, photodetectors, and solar cells) and ICs. ICs and optoelectronic devices each accounted for 41) and optoelectronic devices [mostly laser diodes and light- emitting diodes (LEDs)]. Estimated crude gallium

  9. GALLIUM--1999 29.1 By Deborah A. Kramer

    E-Print Network [OSTI]

    circuits (IC's) were the largest application for gallium, with optoelectronic devices [mostly laser diodes-use application for gallium, with 52% of total consumption. Optoelectronic devices accounted for 42% of domestic% of the gallium consumed in the United States was in the form of GaAs. GaAs was manufactured into optoelectronic

  10. INSTITUTE OF PHYSICS PUBLISHING SEMICONDUCTOR SCIENCE AND TECHNOLOGY Semicond. Sci. Technol. 22 (2007) 2934 doi:10.1088/0268-1242/22/2/006

    E-Print Network [OSTI]

    2007-01-01T23:59:59.000Z

    INSTITUTE OF PHYSICS PUBLISHING SEMICONDUCTOR SCIENCE AND TECHNOLOGY Semicond. Sci. Technol. 22 mismatch between Si and direct bandgap III­V compound semiconductors such as GaAs makes the direct growth of compositionally graded Si1-xGex buffer layers to bridge the gap between Si and GaAs lattice constants (i

  11. Shot noise in self-assembled InAs quantum dots A. Nauen,1,

    E-Print Network [OSTI]

    Hohls, Frank

    they pro- vide zero-dimensional states of microscopic dimensions. Furthermore, it is possible to select structure of 40 40 m2 area. A 15 nm undoped GaAs spacer layer and a GaAs buffer with graded doping on both

  12. Passively modelocked 832 nm vertical-external-cavity surface-emitting

    E-Print Network [OSTI]

    Keller, Ursula

    , focused into an optical spot with dimensions of 100 Ã? 200 mm. The SESAM consisted of an AlAs/Al0.2Ga0.8As DBR, a spacer layer of GaAs0.75P0.25, a 4.8 nm GaAs quantum well and a 2 nm-thick capping layer of Ga

  13. 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. [Spire Corp., Bedford, MA (United States)

    1993-04-01T23:59:59.000Z

    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.

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

    SciTech Connect (OSTI)

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

    1993-04-01T23:59:59.000Z

    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.

  15. 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

    2012-01-01T23:59:59.000Z

    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.

  16. Scanning probe microscopy: Sulfate minerals in scales and cements

    SciTech Connect (OSTI)

    Hall, C. [Schlumberger Cambridge Research (United Kingdom)

    1995-11-01T23:59:59.000Z

    The principles of scanning probe microscopy (SPM) are illustrated with examples from oilfield mineralogy, particularly emphasizing sulfate minerals involved in scale formation and cement hydration chemistry. The topography of the (010) cleavage surface of gypsum observed by atomic force microscopy shows atomically flat terraces separated by shallow steps often only one unit cell high. SPM allows direct observation of processes on mineral surfaces while they are in contact with solutions. The dissolution etching and crystal growth of gypsum and barite are discussed and rates of step migration estimated. The orientation of steps is related to the crystallographic axes. The action of phosphonate crystal growth inhibitor on gypsum and of a chelating scale solvent on barite are also shown. The multiphase microstructure of an oilwell cement clinker is described in relation to its hydration chemistry in contact with water and its reaction with sulfate ions.

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

    SciTech Connect (OSTI)

    NONE

    1996-04-30T23:59:59.000Z

    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.

  18. Didcot B, launch platform for V94.3A

    SciTech Connect (OSTI)

    NONE

    1996-11-01T23:59:59.000Z

    National Power`s fourth combined cycle station at Didcot is now commissioning the first 660 MW block. But at the end of the year, the first examples of Siemens` advanced 240 MW gas turbine, Model V94.3A, will start simple cycle operation pending completion of the steam cycle. National Power`s clean-up strategy has seen emissions of SO{sub 2} and NO{sub x} halved, and CO{sub 2} emissions reduced by 30%. At Drax, a long-term contract with British Gypsum has ensured a market for the gypsum produced in the FGD unit to make plaster board. 3 figs., 1 tab.

  19. Synthesis and characterization of actinide metal compounds formed by combustion

    SciTech Connect (OSTI)

    Behrens, R.G.; King, M.A.

    1985-01-01T23:59:59.000Z

    This paper briefly describes the results of attempts to synthesize arsenides, phosphides, and antimonides of uranium and thorium using Self-Propagating High-Temperature Synthesis (SHS) techniques. This paper first summarizes the chemistry and thermodynamics of these chemical systems, describes SHS synthesis techniques, and then describes the results of the syntheses using data from powder x-ray diffraction, metallographic, and electron microprobe analyses.

  20. Sulfide-Driven Arsenic Mobilization from Arsenopyrite and Black Shale Pyrite

    SciTech Connect (OSTI)

    Zhu, W.; Young, L; Yee, N; Serfes, M; Rhine, E; Reinfelder, J

    2008-01-01T23:59:59.000Z

    We examined the hypothesis that sulfide drives arsenic mobilization from pyritic black shale by a sulfide-arsenide exchange and oxidation reaction in which sulfide replaces arsenic in arsenopyrite forming pyrite, and arsenide (As-1) is concurrently oxidized to soluble arsenite (As+3). This hypothesis was tested in a series of sulfide-arsenide exchange experiments with arsenopyrite (FeAsS), homogenized black shale from the Newark Basin (Lockatong formation), and pyrite isolated from Newark Basin black shale incubated under oxic (21% O2), hypoxic (2% O2, 98% N2), and anoxic (5% H2, 95% N2) conditions. The oxidation state of arsenic in Newark Basin black shale pyrite was determined using X-ray absorption-near edge structure spectroscopy (XANES). Incubation results show that sulfide (1 mM initial concentration) increases arsenic mobilization to the dissolved phase from all three solids under oxic and hypoxic, but not anoxic conditions. Indeed under oxic and hypoxic conditions, the presence of sulfide resulted in the mobilization in 48 h of 13-16 times more arsenic from arsenopyrite and 6-11 times more arsenic from isolated black shale pyrite than in sulfide-free controls. XANES results show that arsenic in Newark Basin black shale pyrite has the same oxidation state as that in FeAsS (-1) and thus extend the sulfide-arsenide exchange mechanism of arsenic mobilization to sedimentary rock, black shale pyrite. Biologically active incubations of whole black shale and its resident microorganisms under sulfate reducing conditions resulted in sevenfold higher mobilization of soluble arsenic than sterile controls. Taken together, our results indicate that sulfide-driven arsenic mobilization would be most important under conditions of redox disequilibrium, such as when sulfate-reducing bacteria release sulfide into oxic groundwater, and that microbial sulfide production is expected to enhance arsenic mobilization in sedimentary rock aquifers with major pyrite-bearing, black shale formations.

  1. Thermionic-photovoltaic energy converter

    SciTech Connect (OSTI)

    Chubb, D. L.

    1985-07-09T23:59:59.000Z

    A thermionic-photovoltaic energy conversion device comprises a thermionic diode mounted within a hollow tubular photovoltaic converter. The thermionic diode maintains a cesium discharge for producing excited atoms that emit line radiation in the wavelength region of 850 nm to 890 nm. The photovoltaic converter is a silicon or galium arsenide photovoltaic cell having bandgap energies in this same wavelength region for optimum cell efficiency.

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

    SciTech Connect (OSTI)

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

    2014-03-17T23:59:59.000Z

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

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

    SciTech Connect (OSTI)

    Friedman, D.

    2013-06-01T23:59:59.000Z

    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.

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

    E-Print Network [OSTI]

    As directly grown on Si, rendering the GaAs useless as a photovoltaic material. Nevertheless, many groups have, this dislocation density has still limited the minority carrier lifetimes obtained to ~ 1-3 ns, even after hydrogen

  5. ambrym island vanuatu: Topics by E-print Network

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

    subpicosecond carrier dynamics C. Kadowa) Materials; accepted for publication 5 October 1999 We report the growth of self-assembled ErAs islands embedded in GaAs by molecular beam...

  6. aphae island shinan-gun: Topics by E-print Network

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

    subpicosecond carrier dynamics C. Kadowa) Materials; accepted for publication 5 October 1999 We report the growth of self-assembled ErAs islands embedded in GaAs by molecular beam...

  7. aphaedo island shinan-gun: Topics by E-print Network

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

    subpicosecond carrier dynamics C. Kadowa) Materials; accepted for publication 5 October 1999 We report the growth of self-assembled ErAs islands embedded in GaAs by molecular beam...

  8. anticosti island laurentia: Topics by E-print Network

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

    subpicosecond carrier dynamics C. Kadowa) Materials; accepted for publication 5 October 1999 We report the growth of self-assembled ErAs islands embedded in GaAs by molecular beam...

  9. aegna island tallinn: Topics by E-print Network

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

    subpicosecond carrier dynamics C. Kadowa) Materials; accepted for publication 5 October 1999 We report the growth of self-assembled ErAs islands embedded in GaAs by molecular beam...

  10. Fabrication of Molecular Devices

    E-Print Network [OSTI]

    Walton, Katherine

    2011-08-04T23:59:59.000Z

    This project focuses on the synthesis and attachment of metal nanoparticles to Au and GaAs surfaces using a combination of chemical self-assembly and scanned probe lithography. In this project self-assembled monolayers (SAMs) of alkanethiols...

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

    E-Print Network [OSTI]

    Groenert, Michael

    2002-01-01T23:59:59.000Z

    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 ...

  12. 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

    2010-01-01T23:59:59.000Z

    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 ...

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

    SciTech Connect (OSTI)

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

    2014-07-07T23:59:59.000Z

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

  14. Exchange Control of Nuclear Spin Diffusion in a Double Quantum Dot

    E-Print Network [OSTI]

    Reilly, D. J.

    The influence of gate-controlled two-electron exchange on the relaxation of nuclear polarization in small ensembles (N?10[superscript 6]) of nuclear spins is examined in a GaAs double quantum dot system. Waiting in the ...

  15. E-Print Network 3.0 - affecting ex-situ aqueous Sample Search...

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

    Heather C.- Department of Chemistry, Ohio State University Collection: Chemistry 76 HfO2 gate dielectric on ,,NH4...2S passivated ,,100... GaAs grown by atomic layer...

  16. Second-order susceptibility from a tight-binding Hamiltonian

    E-Print Network [OSTI]

    Dumitrica, T.; Graves, JS; Allen, Roland E.

    1998-01-01T23:59:59.000Z

    to calculate the energy dependence of X-(2)(omega) for GaAs. The results are in agreement with previous calculations and with available experimental data. [S0163-1829(98)01848-7]....

  17. E-Print Network 3.0 - algaas mid infrared Sample Search Results

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

    processes in the mid-infrared. Bahram Jalali WILEY 20 Macmillan... Flexible optoelectronics PHOTOVOLTAICS of AlGaAs deposited on a GaAs wafer. The clever part of the scheme...

  18. U.S. GEOLOGICAL SURVEY--MINERALS INFORMATION 1 By Deborah A. Kramer

    E-Print Network [OSTI]

    ). to produce optoelectronic devices and integrated circuits for Increased demand for GaAs resulted in several U. Consumption Optoelectronic devices continued to be the largest end use for gallium, with 59% of total

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

    E-Print Network [OSTI]

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

  20. RESEARCH/RESEARCHERS 4 MRS BULLETIN VOLUME 34 JANUARY 2009 www.mrs.org/bulletin

    E-Print Network [OSTI]

    Zhang, Xin

    wallpaper-Group Metamaterials Display Multiple Terahertz Resonances Metamaterials--artificial structures. A standard lift-off process was used to fabricate the metama- terials onto a semi-insulating (SI) GaAs wafer

  1. Substrate engineering for monolithic integration of III-V semiconductors with Si CMOS technology

    E-Print Network [OSTI]

    Dohrman, Carl Lawrence

    2008-01-01T23:59:59.000Z

    Ge virtual substrates, fabricated using Si1-xGex-.Ge, compositionally graded buffers, enable the epitaxial growth of device-quality GaAs on Si substrates, but monolithic integration of III-V semiconductors with Si CMOS ...

  2. MANUSCRIPT PREPARATION TEMPLATE FOR THE 35TH IEEE PHOTOVOLTAIC...

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

    FORM FACTOR GaAs SOLAR CELL Cruz-Campa, J. L. 1 ; Nielson, G. N. 1 ; Okandan, M. 1 ; Wanlass, M. W. 2 ; Sanchez, C. A. 1 ; Resnick. P. J. 1 ; Clews, P. J. 1 ; Pluym, T. 1 ;...

  3. Exploring Self-Assembly and Photomechanical Switching Properties of Molecules at Surfaces

    E-Print Network [OSTI]

    Cho, Jongweon

    2010-01-01T23:59:59.000Z

    11.4 Self-Assembly Properties . . . . . . . . . . . . . 11.512.2 Self-Assembly of TTB-AB on GaAs(110) . . . . . . . 12.3at Surfaces 4 Self-Assembly Properties of Azobenzene on Au(

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

    E-Print Network [OSTI]

    Yeung, King Wah Sunny

    2012-01-01T23:59:59.000Z

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

  5. Low-dimensional carbon nanotube and graphene devices

    E-Print Network [OSTI]

    Scard, Philip

    2010-10-12T23:59:59.000Z

    -jet printing of nanotubes directly onto GaAs. Although only one atom thick, graphene is macroscopic in area and must be patterned to confine conduction; room temperature transistor behaviour requires graphene ribbons only a few nanometres wide. This work...

  6. E-Print Network 3.0 - ambichiral electro-optic structure Sample...

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

    freely propagating continuous-wave terahertz radiation using electro-optic detection. The terahertz... -temperature-grown GaAs. This radiation is detected using the electro-optic...

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

    E-Print Network [OSTI]

    Mariani, Giacomo

    2013-01-01T23:59:59.000Z

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

  8. 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...

  9. Theoretical analysis of strain and strain decay in InAs/GaAs,,001... multilayer quantum dot growth

    E-Print Network [OSTI]

    As or is assumed to change linearly from 50% at the bottom to 100% at the top. The exact QD dimensions GaAs spacer layers typically 20 nm . In these cases not only the effects of In migration

  10. anisotropic magnetoresistive sensor: Topics by E-print Network

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

    Israel (Received 14 March 1996) A periodic array of cylindrical voids, embedded in a thin film of n-doped GaAs, displays a pronounced anisotropy of the classical...

  11. Eighth Annual Student Research

    E-Print Network [OSTI]

    Southern California, University of

    Dongseok Kang Carbon-doped GaAs single junction solar cells grown in multilayer epitaxial assemblies (with and poster session 2:30 PM awards ceremony #12;Posters Graduate student posters Laura Bradley Encapsulation

  12. 2008 Minerals Yearbook U.S. Department of the Interior

    E-Print Network [OSTI]

    , electronic warfare, and phased array radar. The ONR program's objectives were to extend the use of the high voltage Gaas pseudomorphic high electron mobility transistor (pHmET) technology to higher frequencies

  13. VOLUME 84, NUMBER 15 P H Y S I C A L R E V I E W L E T T E R S 10 APRIL 2000 Coherent Control of Absorption and Polarization Decay in a GaAs Quantum Well

    E-Print Network [OSTI]

    Hohng, Sung Chul

    , Renthof 5, D-35032 Marburg, Germany (Received 1 July 1999) Two phase-locked pulses are used to coherently of transform-limited pulses with a pulse duration of 150 fs. We produce two phase-locked collinear pulses excite excitonic polarizations. It is shown that the second pulse can either be strongly amplified

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

    SciTech Connect (OSTI)

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

    2004-09-20T23:59:59.000Z

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

  15. Monitoring interfacial dynamics by pulsed laser techniques

    SciTech Connect (OSTI)

    Richmond, G.L.

    1991-01-01T23:59:59.000Z

    Goal is to develop new optical methods for the study of dynamic processes at the electrode/electrolyte interface. In the past year, optical second harmonic generation was used for time resolved measurements of thallium electrodeposition on Cu(111). Other studies included the study of the photochemistry involved in a GaAs surface treatment known as photowashing, and the study of picosecond time resolved luminescence decays from GaAs in electrochemical environments (power dependent effects). 4 figs. (DLC)

  16. Monitoring interfacial dynamics by pulsed laser techniques. Third yearly progress report

    SciTech Connect (OSTI)

    Richmond, G.L.

    1991-12-31T23:59:59.000Z

    Goal is to develop new optical methods for the study of dynamic processes at the electrode/electrolyte interface. In the past year, optical second harmonic generation was used for time resolved measurements of thallium electrodeposition on Cu(111). Other studies included the study of the photochemistry involved in a GaAs surface treatment known as photowashing, and the study of picosecond time resolved luminescence decays from GaAs in electrochemical environments (power dependent effects). 4 figs. (DLC)

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

    SciTech Connect (OSTI)

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

    2005-11-01T23:59:59.000Z

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

  18. Journal of Electronic Materials, Vol. 17, No. 5, 1988 Effect of Iso-Electronic

    E-Print Network [OSTI]

    Woodall, Jerry M.

    Journal of Electronic Materials, Vol. 17, No. 5, 1988 Effect of Iso-Electronic GaAs Dopants that addition of either one of these two iso-electronic dopants has a similar effect on the solid stoichiometry it is also shown that the addition of the iso-electronic dopants A1 or P to GaAs would not result in the same

  19. Fabrication and characterization of modulation-doped-field-effect-transistors with antidot-patterned passivation layers

    E-Print Network [OSTI]

    Hwang, Sung Woo

    layer with 1 1017 cm 3 Si doping, 50 nm Al0.3Ga0.7As spacer with 1 1018 cm 3 Si doping, 15 nm undoped Al0.3Ga0.7As spacer, 500 nm un- doped GaAs channel layer, 20 periods of 5/5 nm GaAs/ Al. For the demonstration of the internal gate patterning, two types of MODFET's with the same overall gate dimensions

  20. Experimental study of reactions between ozone and building products M. Nicolas, O. Ramalho, F. Maupetit*

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ozone and building products and document their potential impact on indoor air quality. PreliminaryExperimental study of reactions between ozone and building products M. Nicolas, O. Ramalho, F experiments were conducted on four building products: two carpets, a gypsum board and a pine wood board

  1. Non-Traditional Soil Additives: Can They Improve Crop Production?

    E-Print Network [OSTI]

    Mukhtar, Saqib

    residues. 2) Mined mineral deposits that are unprocessed except for grinding. Again, the composi- tion residues, livestock manures and sewage sludge. Non- traditional soil conditioners include both organic potassium), and gypsum or sand. 3) Mined humates or humic acids. These are prehistoric organic deposits

  2. Icarus 196 (2008) 422432 www.elsevier.com/locate/icarus

    E-Print Network [OSTI]

    Bourke, Mary C.

    . Introduction The most extensive sand dune deposit on Mars encircles the north-polar residual water­ice deposit, decreasing in concentration downwind, suggesting deposition via an ae- olian dust plume. Alternate sources of gypsum signature de- tected in the dunefield are thought to be from the polar-layered deposits' basal

  3. Soil and Water Science Department University of Florida RECYLCING OF GUYPSUM DRYWALL IN FLORIDA

    E-Print Network [OSTI]

    Ma, Lena

    Soil and Water Science Department University of Florida RECYLCING OF GUYPSUM DRYWALL IN FLORIDA of landfills in Florida, it is more cost- effective to reuse them. However, there are some concerns the recycling of three important solid wastes in Florida, i.e. #1 cement kiln dust (CKD) and #16 gypsum drywalls

  4. Iron and Steel Phosphate Rock

    E-Print Network [OSTI]

    Torgersen, Christian

    Phosphate Rock Platinum Potash Pumice Quartz Crystal Rare Earths Rhenium Rubidium Salt Sand and Gravel 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

  5. Energy and Buildings 70 (2014) 135144 Contents lists available at ScienceDirect

    E-Print Network [OSTI]

    North Texas, University of

    s t r a c t We have added expanded vermiculite and polypropylene fibers with low thermal conductivity were improved by the addition of expanded silica gel granules introduced into the gypsum [8]. Also://www.unt.edu/LAPOM (W. Brostow). 1 Tel.: +1 940 565 4358; fax: +1 940 565 4824. fiber, polyamide fiber, polyester fiber

  6. Optical properties of the Dead Sea Emmanuel Boss,1

    E-Print Network [OSTI]

    Boss, Emmanuel S.

    has been precipitating salts, in particular NaCl [Anati, 1993; Stiller et al., 1997]. Due to selective, 1983; Anati, 1993; Gavrieli, 1997; Stiller et al., 1997]. In addition, Gavrieli [1997] (and references therein) and Stiller et al. [1997] reported observations of suspended crystals of gypsum and aragonite

  7. 2001 by the Arizona Board of Regents on behalf of the University of Arizona Near East Chronology: Archaeology and Environment. RADIOCARBON, Vol 43, Nr 3, 2001, p 11791189

    E-Print Network [OSTI]

    Yehouda, Enzel

    with respect to salt and gypsum (Neev and Emery 1967; Stiller et al. 1997). The water has a wide range of inorganic radiocarbon composition (Stiller et al. 1988; Talma et al. 1997). Runoff water often formed a less have also occurred naturally in the past (Stiller and Chung 1984) inducing changes in the bottom lake

  8. PORTSMOUTH HARBOR AND PISCATAQUA RIVER, NH & ME NAVIGATION IMPROVEMENT PROJECT

    E-Print Network [OSTI]

    US Army Corps of Engineers

    on the terminals located above Interstate 95. Cargoes include petroleum fuels, cement, gypsum, and liquid propane. The study evaluated project benefits based on reduction in transportation costs generated from a shift. The Recommended Plan will generate significant economic benefits for the nation, and is the National Economic

  9. 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

  10. Burgeoning Biomass: Creating Efficient and Sustainable Forest Biomass Supply Chains in the Rockies

    E-Print Network [OSTI]

    Mountain forests. Most active forest management activities on public and private land, such as thinning be converted into fuel, heat and electricity. Eagle Valley Clean Energy in Gypsum, Colorado, is one such facility, and is Colorado's first dedicated biomass power plant, producing 11.5 megawatts of electricity

  11. Exchangeable sodium accumulation and replacement in Southeast Texas soils under turfgrass

    E-Print Network [OSTI]

    Najjar, Namir Fouad

    1995-01-01T23:59:59.000Z

    accumulation but exchangeable Na also increased as a function of years of irrigation. The multiple regression equation: SARE =-5.16 + 0.53 SARiw + 4.04 In (yr) (R2 = 0.86) best predicted SARE to a depth of 30 cm. This study also compared gypsum, a common...

  12. Harmful algal bloom species and phosphate-processing effluent: Field and laboratory studies

    E-Print Network [OSTI]

    Meyers, Steven D.

    Harbor in southern Tampa Bay (Fig. 1). The State of Florida was then left to dispose of more than 1). Instabilities in the aging phospho- gypsum stacks of the Piney Point phosphate plant, along with potential an emergency permit to the FDEP allowing transport by barge of wastewater to an area greater than 74 km

  13. Particle Size Distribution of Gypseous Samples

    E-Print Network [OSTI]

    Arnett, Morgan P.

    2010-01-16T23:59:59.000Z

    to conditions in the field. In order to understand the true characterization of the soil and the gypsum particles, the entire soil sample should be analyzed. Four different approaches to the BaCl2 method presented in the literature (Hesse, 1976, Matar...

  14. Carbon doping of III-V compound semiconductors

    SciTech Connect (OSTI)

    Moll, A.J.

    1994-09-01T23:59:59.000Z

    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.

  15. Separation of flue-gas scrubber sludge into marketable products. Second quarterly technical progress report, December 1, 1993--February 28, 1994 (Quarter No. 2)

    SciTech Connect (OSTI)

    Kawatra, S.K.; Eisele, T.C.

    1994-03-01T23:59:59.000Z

    To reduce their sulfur emissions, many coal-fired electric power plants use wet flue-gas scrubbers. These scrubbers convert sulfur oxides into solid sulfate and sulfite sludge, which must then be disposed of This sludge is a result of reacting limestone with sulfur dioxide to precipitate calcium sulfite and calcium sulfate. It consists of calcium sulfite (CaSO{sub 3}{lg_bullet}0.5H{sub 2}0), gypsum (CaSO{sub 4}{lg_bullet}2H{sub 2}0), and unreacted limestone (CaCO{sub 3}) or lime (Ca(OH){sub 2}), with miscellaneous objectionable impurities such as iron oxides; silica; and magnesium, sodium, and potassium oxides or salts. Currently, the only market for scrubber sludge is for manufacture of gypsum products, such as wallboard and plaster, and for cement. However, the quality of the raw sludge is often not high enough or consistent enough to satisfy manufacturers, and so the material is difficult to sell. This project is developing a process that can produce a high-quality calcium sulfite or gypsum product while keeping process costs low enough that the material produced will be competitive with that from other, more conventional sources. This purification will consist of minimal-reagent froth flotation, using the surface properties of the particles of unreacted limestone to remove them and their associated impurities from the material, leaving a purified gypsum or calcium sulfite product. The separated limestone will be a useful by-product, as it can be recycled to the scrubber, thus boosting the limestone utilization and improving process efficiency. Calcium sulfite will then be oxidized to gypsum, or separated as a salable product in its own right from sludges where it is present in sufficient quantity. The main product of the process will be either gypsum or calcium sulfite, depending on the characteristics of the sludge being processed. These products will be sufficiently pure to be easily marketed, rather that being landfilled.

  16. Multichannel, time-resolved picosecond laser ultrasound imaging and spectroscopy with custom complementary metal-oxide-semiconductor detector

    SciTech Connect (OSTI)

    Smith, Richard J.; Light, Roger A.; Johnston, Nicholas S.; Pitter, Mark C.; Somekh, Mike G. [Institute of Biophysics, Imaging and Optical Science, University of Nottingham, Nottinghamshire NG7 2RD (United Kingdom); Sharples, Steve D. [Applied Optics Group, Electrical Systems and Optics Research Division, University of Nottingham, Nottinghamshire NG7 2RD (United Kingdom)

    2010-02-15T23:59:59.000Z

    This paper presents a multichannel, time-resolved picosecond laser ultrasound system that uses a custom complementary metal-oxide-semiconductor linear array detector. This novel sensor allows parallel phase-sensitive detection of very low contrast modulated signals with performance in each channel comparable to that of a discrete photodiode and a lock-in amplifier. Application of the instrument is demonstrated by parallelizing spatial measurements to produce two-dimensional thickness maps on a layered sample, and spectroscopic parallelization is demonstrated by presenting the measured Brillouin oscillations from a gallium arsenide wafer. This paper demonstrates the significant advantages of our approach to pump probe systems, especially picosecond ultrasonics.

  17. Nanobeam Photonic Crystal Cavity Light-Emitting Diodes

    E-Print Network [OSTI]

    Shambat, Gary; Petykiewicz, Jan; Mayer, Marie A; Sarmiento, Tomas; Harris, James; Haller, Eugene E; Vuckovic, Jelena

    2011-01-01T23:59:59.000Z

    We present results on electrically driven nanobeam photonic crystal cavities formed out of a lateral p-i-n junction in gallium arsenide. Despite their small conducting dimensions, nanobeams have robust electrical properties with high current densities possible at low drive powers. Much like their two-dimensional counterparts, the nanobeam cavities exhibit bright electroluminescence at room temperature from embedded 1,250 nm InAs quantum dots. A small room temperature differential gain is observed in the cavities with minor beam self-heating suggesting that lasing is possible. These results open the door for efficient electrical control of active nanobeam cavities for diverse nanophotonic applications.

  18. Site control technique for quantum dots using electron beam induced deposition

    SciTech Connect (OSTI)

    Iizuka, Kanji; Jung, JaeHun; Yokota, Hiroshi [Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro, Minami-saitama, Saitama 3458501 (Japan)

    2014-05-15T23:59:59.000Z

    To develop simple and high throughput sit definition technique for quantum dots (QDs), the electron beam induced deposition (EBID) method was used as desorption guide of phosphorus atoms form InP substrate. As the results one or a few indium (In) droplets (DLs) were created in the carbon grid pattern by thermal annealing at a temperature of 450°C for 10 min in the ultra high vacuum condition. The size of In DLs was larger than QDs, but arsenide DLs by molecular beam in growth chamber emitted wavelength of 1.028?m at 50K by photoluminescence measurement.

  19. Site-controlled fabrication of Ga nanodroplets by focused ion beam

    SciTech Connect (OSTI)

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

    2014-03-31T23:59:59.000Z

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

  20. 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 [National Institute of Physics, University of the Philippines Diliman, Quezon City 1101 (Philippines); Que, Christopher T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila 1004 (Philippines); Yamamoto, Kohji; Tani, Masahiko [Research Center for Development of Far-Infrared Region, University of Fukui, Fukui 910-8507 (Japan)

    2012-12-15T23:59:59.000Z

    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.

  1. Substrate structures for InP-based devices

    DOE Patents [OSTI]

    Wanlass, Mark W. (Golden, CO); Sheldon, Peter (Lakewood, CO)

    1990-01-01T23:59:59.000Z

    A substrate structure for an InP-based semiconductor device having an InP based film is disclosed. The substrate structure includes a substrate region having a lightweight bulk substrate and an upper GaAs layer. An interconnecting region is disposed between the substrate region and the InP-based device. The interconnecting region includes a compositionally graded intermediate layer substantially lattice-matched at one end to the GaAs layer and substantially lattice-matched at the opposite end to the InP-based film. The interconnecting region further includes a dislocation mechanism disposed between the GaAs layer and the InP-based film in cooperation with the graded intermediate layer, the buffer mechanism blocking and inhibiting propagation of threading dislocations between the substrate region, and the InP-based device.

  2. Improved substrate structures for InP-based devices

    SciTech Connect (OSTI)

    Wanlass, M.; Sheldon, P.

    1988-09-30T23:59:59.000Z

    A substrate structure for an InP-based semiconductor device having an InP-based film is disclosed. The substrate structure includes a substrate region having a light-weight bulk substrate and an upper GaAs layer. An interconnecting region is disposed between the substrate region and the InP-based device. The interconnecting region includes a compositionally graded intermediate layer substantially lattice matched at its one end to the GaAs layer and substantially lattice matched at its opposite end to the InP-based film. The interconnecting region further includes a dislocation mechanism disposed between the GaAs layer and the InP-based film in cooperation with the graded intermediate layer, the buffer mechanism blocking and inhibiting propagation of threading dislocations between the substrate region and the InP-based device. 1 fig.

  3. General engineering specifications for 6000 tpd SRC-I Demonstration Plant

    SciTech Connect (OSTI)

    Not Available

    1981-11-01T23:59:59.000Z

    This volume contains specifications for architectural features of buildings for the SRC-1 Demonstration Plant: skylights, ventilators, sealants, doors, mirrors, furring and lathing, gypsum plaster, lightweight plaster, wallboard, ceramic tile, acoustic ceiling systems, resilient flooring, carpeting, brick flooring, architectural painting, vinyl wall covering, chalkboards, tackboards, toilets, access flooring, lockers, partitions, washroom accessories, unit kitchens, dock levels, seals, shelters, custom casework, auditorium seats, drapery tacks, prefabricated buildings, stairs, elevators, shelves, etc. (LTN).

  4. Radar investigation of the Hockley salt dome

    E-Print Network [OSTI]

    Hluchanek, James Andrew

    1973-01-01T23:59:59.000Z

    : Geophysics RADAR INVESTIGATION OF THE HOCKLEY SALT DOME A Thesis by UAMES ANDREW HLUCHANEK A'pproved as to style and content by: (Head of Departme t ? Member) May 1. 973 ABSTRACT Radar investigation of the Hockley Salt Dome. . (Nay, 1973) James.... THE PROBLEM. Page A. Probing into Unknown Areas in Salt. . B. Equipment Used. II. BACKGROUND MATERIAL. A. Geology of the Hockley Area. . . B. Economic History of the Hockley Dome Area. . 6 1. Oil 2. Gypsum. 3. Salt C. Geophysical Surveys Over...

  5. HYDRAULIC CEMENT PREPARATION FROM LURGI SPENT SHALE

    SciTech Connect (OSTI)

    Mehta, P.K.; Persoff, P.; Fox, J.P.

    1980-06-01T23:59:59.000Z

    Low cost material is needed for grouting abandoned retorts. Experimental work has shown that a hydraulic cement can be produced from Lurgi spent shale by mixing it in a 1:1 weight ratio with limestone and heating one hour at 1000°C. With 5% added gypsum, strengths up to 25.8 MPa are obtained. This cement could make an economical addition up to about 10% to spent shale grout mixes, or be used in ordinary cement applications.

  6. Experimental and Analytical Research on Fracture Processes in ROck

    SciTech Connect (OSTI)

    Herbert H.. Einstein; Jay Miller; Bruno Silva

    2009-02-27T23:59:59.000Z

    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.

  7. Salinity Control in Irrigation Agriculture.

    E-Print Network [OSTI]

    Lyerly, Paul J.; Longenecker, Donald E.

    1962-01-01T23:59:59.000Z

    streams and under- ground sources contain dissolved substances known chemically as salts. Ocean water contains approximately 3 percent salts, or 40 tons of salts per acre-foot of water. Waters used for irriga- tion generally contain .1 to 5 tons... of salt per acre-foot of water. In general terms, salt is thought of as table alt; however, thousands of different salts are known. Examples of common salts in irrigation water are table salt (sodium chloride), Epsom salt (magnesium sulfate), gypsum...

  8. Biological treatment options for consolidated tailings release waters

    SciTech Connect (OSTI)

    Gunter, C.P.; Nix, P.G.; Sander, B. [EVS Environment Consultants, North Vancouver, British Columbia (Canada); Knezevic, Z.

    1995-12-31T23:59:59.000Z

    Suncor Inc., Oil Sands Group, operates a large oil sands mining and extraction operation in northeastern Alberta. The extraction plant produces large volumes of a tailings slurry which resists dewatering and treatment, and is toxic to aquatic organisms. Consolidated tailings (CT) technology is used to treat tailings by either acid/lime or gypsum and enhances the possibility of treating residual fine tails in a ``dry`` land reclamation scenario and treating the release water in a wastewater treatment reclamation scenario. The objective was to assess the treatability of CT release water (i.e., the reduction of acute and chronic toxicities to trout, Ceriodaphnia, and bacteria) in bench-scale biological treatment systems. Microtox{reg_sign} IC20 test showed complete detoxification for the gypsum CT release water within 3 to 5 weeks compared with little reduction in toxicity for dyke drainage. Acute toxicity (fish) and chronic toxicity (Ceriodaphnia, bacterial) was removed from both CT release waters. Phosphate and aeration enhanced detoxification rates. Concentrations of naphthenic acids (an organic toxicant) were not reduced, but levels of dissolved organic compounds decreased faster than was the case for dyke drainage water, indicating that some of the organic compounds in both acid/lime and gypsum CT waters were more biodegradable. There was a pattern of increasing toxicity for dyke drainage water which confirmed observations during field-scale testing in the constructed wetlands and which was not observed for CT release waters. Acid/lime and gypsum CT water can be treated biologically in either an aeration pond, constructed wetlands, or a combination of both thereby avoiding the expense of long-term storage and/or conventional waste treatment systems.

  9. Controlling Emissions of SOx and NOx from power plants

    E-Print Network [OSTI]

    Toohey, Darin W.

    #12;Sulfur Removal Sulfur is removed from crude oil by the catalytic reaction: R-S + H2 H2S + R Until the mid 1970's the H2S was mixed back into the fuel gas. The problem with this is that the H2S is burned + CO2 This is a two step process including the scrubber and the effluent hold tank. CaSO4 (gypsum

  10. Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur. Fifth quarterly technical progress report, December 1996

    SciTech Connect (OSTI)

    NONE

    1996-12-01T23:59:59.000Z

    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}.

  11. Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur. Sixth quarterly technical progress report, January - March 1997

    SciTech Connect (OSTI)

    NONE

    1997-03-01T23:59:59.000Z

    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}.

  12. Advanced Byproduct Recovery: Direct Catalytic Reduction of Sulfur Dioxide to Elemental Sulfur.

    SciTech Connect (OSTI)

    NONE

    1997-06-01T23:59:59.000Z

    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}.

  13. Current-matched high-efficiency, multijunction monolithic solar cells

    DOE Patents [OSTI]

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

    1993-01-01T23:59:59.000Z

    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

  14. 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 [Institute of Physical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg (Germany)

    2014-08-07T23:59:59.000Z

    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.

  15. Interfacial oxide re-growth in thin film metal oxide III-V semiconductor systems

    SciTech Connect (OSTI)

    McDonnell, S.; Dong, H.; Hawkins, J. M.; Brennan, B.; Milojevic, M.; Aguirre-Tostado, F. S.; Zhernokletov, D. M.; Hinkle, C. L.; Kim, J.; Wallace, R. M.

    2012-04-02T23:59:59.000Z

    The Al{sub 2}O{sub 3}/GaAs and HfO{sub 2}/GaAs interfaces after atomic layer deposition are studied using in situ monochromatic x-ray photoelectron spectroscopy. Samples are deliberately exposed to atmospheric conditions and interfacial oxide re-growth is observed. The extent of this re-growth is found to depend on the dielectric material and the exposure temperature. Comparisons with previous studies show that ex situ characterization can result in misleading conclusions about the interface reactions occurring during the metal oxide deposition process.

  16. Observation of the Kondo effect in a spin-3/2 hole quantum dot

    SciTech Connect (OSTI)

    Klochan, O.; Micolich, A. P.; Hamilton, A. R. [School of Physics, University of New South Wales, Sydney NSW 2052 (Australia); Trunov, K.; Reuter, D.; Wieck, A. D. [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2013-12-04T23:59:59.000Z

    We report the observation of the Kondo effect in a spin-3/2 hole quantum dot formed near pinch-off in a GaAs quantum wire. We clearly observe two distinctive hallmarks of quantum dot Kondo physics. First, the zero-bias peak in the differential conductance splits an in-plane magnetic field and the splitting is independent of gate voltage. Second, the splitting rate is twice as large as that for the lowest one-dimensional subband. We show that the Zeeman splitting of the zero-bias peak is highly anisotropic and attribute this to the strong spin-orbit interaction for holes in GaAs.

  17. Isoelectronic co-doping

    DOE Patents [OSTI]

    Mascarenhas, Angelo

    2004-11-09T23:59:59.000Z

    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.

  18. Thickness dependence of magnetic anisotropy in thin Ni films electrodeposited onto the (011) and (001) surfaces of n-GaAs

    SciTech Connect (OSTI)

    Gubbiotti, G.; Carlotti, G.; Tacchi, S.; Liu, Y.-K.; Scheck, C.; Schad, R.; Zangari, G. [INFM CRS-SOFT, c/o Universita di Roma 'La Sapienza', I-00185, Rome (Italy); INFM UdR-Perugia, c/o Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, 06123 Perugia (Italy); INFM-National Center for nanoStructures and bioSystem at Surfaces (S3) Modena, and Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, 06123 Perugia (Italy); IINFM UdR-Perugia, Dipartimento di Fisica, Universita di Perugia, Via A. Pascoli, 06123 Perugia (Italy); MINT Center, University of Alabama, Tuscaloosa Alabama 35401 (United States); Department of Materials Science and Engineering and Center for Electrochemical Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2005-05-15T23:59:59.000Z

    Brillouin light scattering from thermal spin waves has been exploited to investigate the thickness dependence of magnetic anisotropy of Ni films, with thickness in the range 7-35 nm, grown by electrodeposition onto either (011)- or (001)-GaAs substrates. In the former case, Ni films exhibit a well-defined in-plane uniaxial anisotropy induced by the symmetry of the substrate. In the case of the (001)-GaAs substrate, instead, the magnetic anisotropy results from a combination of both a fourfold and a twofold contribution. The physical mechanisms responsible for the observed anisotropy, as well as its dependence on film thickness, are discussed in detail.

  19. Evaluation of growth methods for the heteroepitaxy of non-polar (11-20) GaN on sapphire by MOVPE

    E-Print Network [OSTI]

    Oehler, F.; Sutherland, D.; Zhu, T.; Emery, R.; Badcock, T. J.; Kappers, M. J.; Humphreys, C. J.; Dawson, P.; Oliver, R. A.

    2014-09-16T23:59:59.000Z

    double grating spectrometer equipped with a Peltier-cooled GaAs photomultiplier tube. The spectra were recorded with signal lock-in processing techniques. As the HeCd laser absorption length is ca. 350 nm for 99% absorption in GaN (ignoring any carrier... double grating spectrometer equipped with a Peltier-cooled GaAs photomultiplier tube. The spectra were recorded with signal lock-in processing techniques. As the HeCd laser absorption length is ca. 350 nm for 99% absorption in GaN (ignoring any carrier...

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

    E-Print Network [OSTI]

    A. E. Nikolaenko; E. A. Chekhovich; M. N. Makhonin; I. W. Drouzas; A. B. Vankov; J. Skiba-Szymanska; M. S. Skolnick; P. Senellart; A. Lemaitre; A. I. Tartakovskii

    2009-01-15T23:59:59.000Z

    Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

  1. Field Testing of Nano-PCM Enhanced Building Envelope Components

    SciTech Connect (OSTI)

    Biswas, Kaushik [ORNL; Childs, Phillip W [ORNL; Atchley, Jerald Allen [ORNL

    2013-08-01T23:59:59.000Z

    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.

  2. APPLIED PHYTO-REMEDIATION TECHNIQUES USING HALOPHYTES FOR OIL AND BRINE SPILL SCARS

    SciTech Connect (OSTI)

    M.L. Korphage; Bruce G. Langhus; Scott Campbell

    2003-03-01T23:59:59.000Z

    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.

  3. Superficies y Vacio 8, 85-88(1999) Sociedad Mexicana de Ciencias de Superficies y de Vaco. Optical and structural characterization of the heterostructure CdTe/GaAs

    E-Print Network [OSTI]

    Meléndez Lira, Miguel Angel

    of the characterization of CdTe thin films grown by radio frequency sputtering employing GaAs substrates subject oxides on the properties of CdTe films. The three different chemical procedures were: (1) H2SO4+ H2SO4 for the usual values found for CdTe films grown by RF sputtering. From photoluminescence measurements we can say

  4. Substrate effect on CdTe layers grown by metalorganic vapor phase N. V. Sochinskiia),b)

    E-Print Network [OSTI]

    Viña, Luis

    Substrate effect on CdTe layers grown by metalorganic vapor phase epitaxy N. V. Sochinskiia for publication 30 December 1996 CdTe layers were grown by metalorganic vapor phase epitaxy MOVPE on different substrates like sapphire, GaAs, and CdTe wafers. The growth was carried out at the temperature 340 °C

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

    E-Print Network [OSTI]

    Tsai, Chia-Ho

    2006-01-01T23:59:59.000Z

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

  6. Midwave infrared quantum dot avalanche photodiode David A. Ramirez,a

    E-Print Network [OSTI]

    Hayat, Majeed M.

    Midwave infrared quantum dot avalanche photodiode David A. Ramirez,a Jiayi Shao, Majeed M. Hayat demonstration of a GaAs based avalanche photodiode APD operating in the midwave infrared region 3­5 m . In the device, called the quantum dot avalanche photodiode, an intersubband quantum dots-in-a-well detector

  7. 54 IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY, VOL. 1, NO. 2, FEBRUARY 2013 Multi-Gain-Stage InGaAs Avalanche Photodiode

    E-Print Network [OSTI]

    Hayat, Majeed M.

    GaAs Avalanche Photodiode with Enhanced Gain and Reduced Excess Noise George M. Williams, Madison Compton, David, and test of an InGaAs avalanche photodiode (APD) for 950­1650 nm wave- length sensing applications. The APD over 1 000. Index Terms--Avalanche photodiode, optical receiver, photo detector, photon counting. I

  8. Density-functional study of Mn monosilicide on the Si(111) surface: Film formation versus island nucleation

    E-Print Network [OSTI]

    . In most cases, a transition metal silicide is formed instead of the desired metal film. This is in contrast to Fe on GaAs, where metallic Fe films were obtained. The silicides formed on Si, e.g., bulk Fe

  9. Nano-photonic Light Trapping In Thin Film Solar Dennis M. Callahan Jr.

    E-Print Network [OSTI]

    Winfree, Erik

    Nano-photonic Light Trapping In Thin Film Solar Cells Thesis by Dennis M. Callahan Jr. In Partial. Jeremy Munday for helping me get started on the thin-film GaAs project and for all the time we spent to thank Dr. Jonathan Grandidier for working closely with me for a couple years on the nano sphere solar

  10. Midinfrared scattering and absorption in Ge powder close to the Anderson localization transition J. Gomez Rivas, R. Sprik, and A. Lagendijk

    E-Print Network [OSTI]

    Sprik, Rudolf

    localization (kls 1) of near infrared light was reported in GaAs (n 3.5) powder samples consisting of randomly a free electron laser we have performed midinfrared transmission and reflection measurements in strongly transition. The refractive index of Ge is very high in the near and midinfrared (n 4.0) 8

  11. DOI: 10.1002/adma.200700536 A Photosynthetic Reaction Center Covalently Bound to Carbon

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    DOI: 10.1002/adma.200700536 A Photosynthetic Reaction Center Covalently Bound to Carbon Nanotubes of PS I proteins to carbon nanotubes (CNTs).[7] The method al- lows studying hybrid nanosystems to GaAs surfaces.[6] To this end, amino acids in the extra membrane loops of the PS I facing the cyto

  12. IEEE ELECTRON DEVICE LETTERS. VOL. EDL-6, NO. 10, OCTOBER 1985 491 J. J. ROSENBERG, M. BENLAMRI, P. D. KIRCHNER, J. M. WOODALL, AND G. D. PETTIT

    E-Print Network [OSTI]

    Woodall, Jerry M.

    IEEE ELECTRON DEVICE LETTERS. VOL. EDL-6, NO. 10, OCTOBER 1985 491 J. J. ROSENBERG, M. BENLAMRI, P of the reported heterojunction FET devices utilize A1,Gal _,As/ GaAs heterojunctions in which electrons. D. KIRCHNER, J. M. WOODALL, AND G. D. PETTIT Abstract-This letter describes high electron mobility

  13. Guided self-assembly of Au nanocluster arrays electronically coupled to semiconductor device layers

    E-Print Network [OSTI]

    Woodall, Jerry M.

    Guided self-assembly of Au nanocluster arrays electronically coupled to semiconductor device layers clusters within patterned regions on GaAs device layers, thus demonstrating guided self-assembly on a substrate which can provide interesting semiconductor device characteristics. Uniform nanometer scale

  14. SO8 IEEE PHOTONICS TECHNOLOGY LETTERS. VOL. 7 , NO. S. MAY 1995 Monolithic Optoelectronic Circuit Design

    E-Print Network [OSTI]

    Shenoy, Krishna V.

    SO8 IEEE PHOTONICS TECHNOLOGY LETTERS. VOL. 7 , NO. S. MAY 1995 Monolithic Optoelectronic Circuit optoelectronic integration technique was proposed based on this circuit stability and consequently the monolithic integration of LED's and GaAs circuits by molecular beam epitaxial (MBE) growth, to form an optoelectronic

  15. 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

  16. David Patel, Ishiang Shih Department of Electrical Engineering, McGill University , QC, Canada

    E-Print Network [OSTI]

    Barthelat, Francois

    David Patel, Ishiang Shih Department of Electrical Engineering, McGill University , QC, Canada electrical consumption. [2] GaN Material Properties ·Wurtzite structure oNo inversion symmetry oEach element operations oReported up to ~500oC ·Lower mobility vs. GaAs oDue to higher alloy scattering in nitrides. o

  17. Optically initiated silicon carbide high voltage switch

    DOE Patents [OSTI]

    Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Sullivan, James S. (Livermore, CA); Sanders; David M. (Livermore, CA)

    2011-02-22T23:59:59.000Z

    An improved photoconductive switch having a SiC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

  18. Optically-initiated silicon carbide high voltage switch

    DOE Patents [OSTI]

    Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Sullivan, James S. (Livermore, CA); Sanders, David M. (Livermore, CA)

    2012-02-28T23:59:59.000Z

    An improved photoconductive switch having a SIC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

  19. NON-LINEAR OPTICS IN SEMICONDUCTORS POST DOCTORAL POSITION, PHOTONICS GROUP,

    E-Print Network [OSTI]

    covering most of the infrared region of the spectrum. Harnessing nonlinear interactions is imperative for these devices. In contrast to lithium niobate, compound semiconductors such as GaAs-based compounds exhibit for lithium niobate. GaAs compounds also have high damage threshold and a mature fabrication technology

  20. Doping of G Molecular Layer D

    E-Print Network [OSTI]

    Candea, George

    Metal n-SC n++ SC EF EC � 0.5 eV Metal n-SCn++ SC Raman Spectrum of Different Crystal OrientationsGe, the remaining amorphous Ge is transported through the germanide to grow epitaxially on the GaAs. ·Epitaxial

  1. Harry Atwater is the Howard Hughes Professor of Applied Physics and Materials Science at the California

    E-Print Network [OSTI]

    Faraon, Andrei

    efficiency/low cost GaAs photovoltaics technology, and of Caelux Corporation, a venture-backed photovoltaics interests have two themes: photovoltaics and solar energy as well as plasmonics and optical metamaterials. His group has created new high efficiency solar cell designs, and have developed principles for light

  2. Department of Physics & Astronomy Experimental Particle Physics Group

    E-Print Network [OSTI]

    Glasgow, University of

    in the future ATLAS experiment at the LHC imposes severe demands on the radiation hardness of the GaAs detectors were performed at the ISIS facility [2] for the neutron exposure, with a spectrum strongly peaked at 1 of the ATLAS semiconductor tracker. 3 Reverse Current The effect of all three types of irradiation

  3. DOI: 10.1007/s00339-003-2405-0 Appl. Phys. A 78, 465469 (2004)

    E-Print Network [OSTI]

    -GaAs) or radiation-damaged Si on sapphire, that are time gated by a synchronised probe pulse [4, 10]. Electro- optic stimulated by the development of new effi- cient methods to generate and detect far-infrared radiation pulses to broadband far-infrared radiation. For instance, the frequency compo- nents in the bandwidth

  4. Guided Self-Assembly of Au Nanocluster Arrays Electronically Coupled to Semiconductor Device Layers

    E-Print Network [OSTI]

    Guided Self-Assembly of Au Nanocluster Arrays Electronically Coupled to Semiconductor Device Layers diameter Au clusters within patterned regions on GaAs device layers, thus demonstrating guided self-assembly ordering of the clusters is achieved by a chemical self- assembly process, while micron scale patterning

  5. Self-assembly of triangular quantum dots on (111)A substrates by droplet epitaxy

    SciTech Connect (OSTI)

    Jo, M.; Mano, T.; Abbarchi, M.; Kuroda, T. [Advanced Photonics Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Sakoda, K. [Advanced Photonics Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan and Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan)

    2014-05-15T23:59:59.000Z

    We report the self-assembly of triangular GaAs quantum dots (QDs) on (111)A substrates using droplet epitaxy. Shape transition from hexagonal to triangular QDs is observed with increasing crystallizing temperature. The mechanism of the morphological change is discussed in terms of different growth rates of step edges on a (111)A substrate.

  6. CURRENT NEWS Sandwich Solar Cells May See Off Silicon

    E-Print Network [OSTI]

    Rogers, John A.

    CURRENT NEWS Sandwich Solar Cells May See Off Silicon May 24, 2010 A new manufacturing technique of devices using GaAs chips manufactured in multilayer stacks: light sensors, high-speed transistors and solar cells. The authors also provide a detailed cost comparison. Another advantage of the multilayer

  7. Belgirate, Italy, 28-30 September 2005 BONDING SEMICONDUCTOR LASER CHIPS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    without thermo- electric cooler, so called uncooled modules, establish themselves as a cost will discuss here a model to determine the substrate material giving the best chip reliability expectations for GaAs and InP laser chips. In that respect, a comparison of the thermo-mechanical stresses induced

  8. 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]

    GaAs laser. Also, in a monolithically integrated thermo- electric cooled InGaAsP/InP laser diode, Dutta et ~1 temperature of f 7.5 "C has been achieved using f 100 mA of thermoelectric cooler current. The observed" thermoelectric cooler, or a mono- lithically integrated thermoelectric cooler. Hava et ~1.~ ob- served a 2 "C

  9. Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells

    E-Print Network [OSTI]

    Atwater, Harry

    Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells Vivian E. Ferry, Luke in thin film solar cells. In particular, the ability of plasmonic structures to localize light sunlight into guided modes in thin film Si and GaAs plasmonic solar cells whose back interface is coated

  10. TIME-RESOLVED TERAHERTZ TRANSMISSION SPECTROSCOPY OF DIELECTRICS

    E-Print Network [OSTI]

    Ku?el, Petr

    semiconductor surfaces in bulk semiconductor wafers[5,6,7], etc. The detection techniques which are based in fact constitutes a bridge between the classical IR spectroscopy domain and the frequencies accessible polar excitations in optical materials like sapphire and quartz[15], in semiconductors (Ge, GaAs, Si

  11. Low Cost RF MEMS Switches Fabricated on Microwave Laminate Printed Circuit Boards

    E-Print Network [OSTI]

    De Flaviis, Franco

    have been demonstrated with superior performance over conventional semiconductor devices [4. They are normally built on high-resistivity silicon wafers, GaAs wafers, and quartz substrates using semiconductor prior to deposition of a metal membrane bridge, which poses a major challenge to manufacturability

  12. 2152 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 17, NO. 11, NOVEMBER 1999 One-Dimensional Photonic Bandgap Microcavities

    E-Print Network [OSTI]

    Fan, Shanhui

    Bandgap Microcavities for Strong Optical Confinement in GaAs and GaAs/Al O Semiconductor Waveguides Daniel been designed, fabricated using high-dielectric-contrast GaAs/AlxOy III­V com- pound semiconductor air-bridge geometries. Resonance states with cavity Q's as high as 360 were measured at wavelengths

  13. Structural Studies of Potential 1 eV Solar Cell Materials

    SciTech Connect (OSTI)

    Norman, A.; Al-Jassim, M.; Friedman, D.; Geisz, J.; Olson, J.; Kurtz, S.

    2000-01-01T23:59:59.000Z

    Structural studies using transmission electron microscopy have been made on 1-eV band-gap materials, lattice-matched to GaAs and Ge substrates, grown by metal-organic vapor-phase epitaxy for use in multijunction, high-efficiency solar cells.

  14. P. MCK Cryst. Res. Technol. 35 (2000) 529-540 Department of Materials, University of Oxford

    E-Print Network [OSTI]

    Moeck, Peter

    Comparison of Experiments and Theories for Plastic Deformation in thermally processed GaAs Wafers Different single crystal X-ray transmission topography, scanning infrared polariscopy, visible light interferometry that reduces the yield of electronic devices in manufacturing processes on an industrial scale [KIYAMA et al

  15. 2076 OPTICS LETTERS / Vol. 27, No. 23 / December 1, 2002 Ultrasensitive and high-dynamic-range two-photon absorption

    E-Print Network [OSTI]

    Murphy, Thomas E.

    -photon absorption near 1.5 mm in several devices, including silicon avalanche1 and nonavalanche2 pho- todiodes, InGaAsP-photon absorption in a GaAs photomultiplier tube Jeffrey M. Roth and T. E. Murphy MIT Lincoln Laboratory, Lexington, 2002 We demonstrate improved efficiency and dynamic range for two-photon absorption at 1.5 mm

  16. DOI: 10.1007/s00339-007-4322-0 Appl. Phys. A 90, 105112 (2008)

    E-Print Network [OSTI]

    Woodall, Jerry M.

    in direct-band-gap semicon- ductors (e.g. InGaAsP). Our deep cen- ters in GaAs also achieved a total radia at the same wavelengths because both emission and absorption are governed by the same optical dipole absorption at laser wavelengths. Thus, strong self- absorption at luminescent wavelengths raises

  17. Circuit QED in a double quantum dot system

    SciTech Connect (OSTI)

    Toida, Hiraku; Nakajima, Takashi; Komiyama, Susumu [Department of Basic Science, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902 (Japan)

    2013-12-04T23:59:59.000Z

    Strong coupling peculiar feature is demonstrated in a coupled qubit-resonator system consisting of a GaAs double quantum dot and a coplanar waveguide resonator. Qubit-resonator coupling strength (g and the decoherence rate ? are directly derived from the experiment, assuring a strong coupling condition (g/? ? 2)

  18. Journal of Electronic Materials, Vol. 19, No, 4, 1990 Carbon Tetrachloride Doped AIxGa_xAS

    E-Print Network [OSTI]

    Cunningham, Brian

    Journal of Electronic Materials, Vol. 19, No, 4, 1990 Carbon Tetrachloride Doped AIx been shown to be a suitable carbon doping source for obtaining p-type GaAs grown by metalorganic chemical vapor deposition (MOCVD) with carbon acceptor concentrations in excess of 1 x 1019cm-3

  19. PICPOT: A NANOSATELLITE FROM TURIN POLYTECHNIC S. Speretta1

    E-Print Network [OSTI]

    . The main goals of this satellite are the transmission of on-board telemetry measures (solar panel-Board Computer), time scheduler and RF mod- ule (437 MHz and 2.44 GHz). Solar power is granted by 5 GaAs solar panel with 5 MPPT (Maximum Power Point Tracker) to charge the batteries. The satellite hosts

  20. Local far-infrared spectroscopy of edge states in the quantum Hall regime A. Lorke* and J. P. Kotthaus

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    resolution well below typical Hall bar dimensions,7,8 the other is the use of the edge channels them- selves are as follows: Buffer and smoothing layers, 1 m GaAs, a 15-nm AlxGa1 xAs (x 0.3) spacer layer, 3.9 1012 - cm 2

  1. Edge magnetoplasmons in single two-dimensional electron disks at microwave frequencies: Determination of the lateral depletion length

    E-Print Network [OSTI]

    Ludwig-Maximilians-Universität, München

    differs from the 3D case because of the particular screening proper- ties in lower dimensions. In devices, a 200-Ã?-thick AlxGa1 xAs spacer layer, a 400 Ã? Si-doped AlxGa1 xAs layer, and a 200 Ã? GaAs cap layer

  2. Criteria for One-Dimensional Transport in Split-Gate Field-Effect Transistors Cristopher C. Eugster, JesGs A. del Alamo, Paul A. Belk and Michael J. Rooks'

    E-Print Network [OSTI]

    del Alamo, Jesús A.

    miniaturization of today's electronic devices will soon lead to devices with dimensions comparable to the electron" cm-$, a 7.5 nm undoped AlGaAs spacer, and a 1 pm GaAs buffer. The mobility of the 2D elec- tron gas

  3. Spatiotemporal shaping of half-cycle terahertz pulses by diffraction through

    E-Print Network [OSTI]

    Stroud, Carlos R.

    demonstrate a simple quasi-optical technique for spatiotemporal shaping of half-cycle terahertz-radiation (such as GaAs, InP, or CdTe) or radiation-damaged silicon-on-sapphire. Generated carri- ers are rapidly of finite thickness Jake Bromage, Stojan Radic, G. P. Agrawal, and C. R. Stroud, Jr. The Institute of Optics

  4. Amber-green light-emitting diodes using order-disorder Al[subscript x]In[subscript 1?x]P heterostructures

    E-Print Network [OSTI]

    Christian, Theresa M.

    We demonstrate amber-green emission from Al[subscript x]In[subscript 1– x]P light-emitting diodes (LEDs) with luminescence peaked at 566?nm and 600?nm. The LEDs are metamorphically grown on GaAs substrates via a graded ...

  5. Difference-frequency generation in AlGaAs Bragg reflection waveguides

    E-Print Network [OSTI]

    -matching (BPM) [5,6] and quasi-phase-matching [7,8]. Among these, BPM has been shown to be the most efficient with the absorption of GaAs below 870 nm in wavelength, limits the operating window of BPM devices for infrared

  6. Solidification of ion exchange resin wastes

    SciTech Connect (OSTI)

    Not Available

    1982-08-01T23:59:59.000Z

    Solidification media investigated included portland type I, portland type III and high alumina cements, a proprietary gypsum-based polymer modified cement, and a vinyl ester-styrene thermosetting plastic. Samples formulated with hydraulic cement were analyzed to investigate the effects of resin type, resin loading, waste-to-cement ratio, and water-to-cement ratio. The solidification of cation resin wastes with portland cement was characterized by excessive swelling and cracking of waste forms, both after curing and during immersion testing. Mixed bed resin waste formulations were limited by their cation component. Additives to improve the mechanical properties of portland cement-ion exchange resin waste forms were evaluated. High alumina cement formulations dislayed a resistance to deterioration of mechanical integrity during immersion testing, thus providing a significant advantage over portland cements for the solidification of resin wastes. Properties of cement-ion exchange resin waste forms were examined. An experiment was conducted to study the leachability of /sup 137/Cs, /sup 85/Sr, and /sup 60/Co from resins modified in portland type III and high alumina cements. The cumulative /sup 137/Cs fraction release was at least an order of magnitude greater than that of either /sup 85/Sr or /sup 60/Co. Release rates of /sup 137/Cs in high alumina cement were greater than those in portland III cement by a factor of two.Compressive strength and leach testing were conducted for resin wastes solidified with polymer-modified gypsum based cement. /sup 137/Cs, /sup 85/Sr, and /sup 60/Co fraction releases were about one, two and three orders of magnitude higher, respectively, than in equivalent portland type III cement formulations. As much as 28.6 wt % dry ion exchange resin was successfully solidified using vinyl ester-styrene compared with a maximum of 25 wt % in both portland and gypsum-based cement.

  7. The desulfurization of flue gas at the Mae Moh Power Plant Units 12 and 13

    SciTech Connect (OSTI)

    Haemapun, C.

    1993-12-31T23:59:59.000Z

    As pollution of air, water and ground increasingly raises worldwide concern, the responsible national and international authorities establish and issue stringent regulations in order to maintain an acceptable air quality in the environment. In Thailand, the Electricity Generating Authority of Thailand (EGAT) takes full responsibility in environmental protection matters as well as in generating the electricity needed to supply the country`s very rapid power demand growth. Due to the rapidly increasing electricity demand of the country, EGAT had decided to install two further lignite-fired units of 300 MW each (Units 12 and 13) at the Mae Moh power generation station and they are now under construction. The arrangement and the capacity of all the power plant units are as shown. In 1989, EGAT started the work on the flue gas desulfurization system of Mae Moh power plant units 12 and 13 as planned. A study has been conducted to select the most suitable and most economical process for flue gas desulfurization. The wet scrubbing limestone process was finally selected for the two new units. Local limestone will be utilized in the process, producing a by-product of gypsum. Unfortunately, natural gypsum is found in abundance in Thailand, so the produced gypsum will be treated as landfill by mixing it with ash from the boilers of the power plants and then carrying it to the ash dumping area. The water from the waste ash water lake is utilized in the process as much as possible to minimize the requirement of service water, which is a limited resource. The Mae Moh power generation station is situated in the northern region of Thailand, 600 km north of Bangkok and about 30 km east of the town of Lampang, close to the Mae Moh lignite mine. Three lignite-fired units (Units 1-3) of 75 MW each, four units (Units 4-7) of 150 MW each and four units (Units 8-11) of 300 MW each are in operation.

  8. Anisotropic Energy Gaps of Iron-Based Superconductivity from Intraband Quasiparticle Interference in LiFeAs

    SciTech Connect (OSTI)

    Davis J. C.; Allan, M.P.; Rost, A.W.; Mackenzie, A.P.; Xie, Y.; Kihou, K.; Lee, C.H.; Iyo, A.; Eisaki, H.; Chuang, T.-M.

    2012-05-04T23:59:59.000Z

    If strong electron-electron interactions between neighboring Fe atoms mediate the Cooper pairing in iron-pnictide superconductors, then specific and distinct anisotropic superconducting energy gaps {Delta}{sub i}(k) should appear on the different electronic bands i. Here, we introduce intraband Bogoliubov quasiparticle scattering interference (QPI) techniques for determination of {Delta}{sub i}(k) in such materials, focusing on lithium iron arsenide (LiFeAs). We identify the three hole-like bands assigned previously as {gamma}, {alpha}{sub 2}, and {alpha}{sub 1}, and we determine the anisotropy, magnitude, and relative orientations of their {Delta}{sub i}(k). These measurements will advance quantitative theoretical analysis of the mechanism of Cooper pairing in iron-based superconductivity.

  9. Innovation in photoelectrodes for the splitting of water

    SciTech Connect (OSTI)

    Lindmayer, J.

    1986-10-15T23:59:59.000Z

    Generation of hydrogen from a renewable energy source is highly desirable because hydrogen is a basic fuel. Past work has shown that certain semiconductor electrodes will generate hydrogen directly upon illumination; however, the efficiency of such systems is low. This work explored an idea based on a 'hot electron gun' where freshly generated hot electrons are made to interact with water. The work attempted to show, through the use of three semiconductors (germanium, gallium arsenide, and silicon), that hot electrons could be tunneled into the electrolyte. Numerous thin metals were used to form a tunneling interface. Particularly interesting results were obtained with a titanium-palladium double layer and with indium-tin oxide. The presence of hot-electron activity was detected and the threshold voltage for hydrogen generation was reduced to below half a volt.

  10. Product development of FGD recovered magnesium hydroxide

    SciTech Connect (OSTI)

    Beeghly, J.H.; Babu, M.; Smith, K.J.

    1999-07-01T23:59:59.000Z

    The ThioClear FGD processes developed by the Dravo Lime Company (DLC) produce a high brightness gypsum and magnesium hydroxide (Mg(OH){sub 2}) by-product. Both originate as white precipitates from a solution of magnesium sulfate. The use of magnesium-enhanced lime avoids the mineral impurities from direct neutralization when using pulverized limestone rock. White, pure FGD synthetic gypsum can be used to produce higher value products such as mineral fillers and industrial plasters. This paper focuses on the product development of the Mg(OH){sub 2} by-product. Commercial Mg(OH){sub 2} sells at over $200/Ton for a variety of uses, most of which is wastewater treatment and a feedstock to make magnesium chemicals and refractories. Beneficial uses in the power plant are pH control of acidic coal pile stormwater runoff and bottom ash quench water. A future use being explored is injection into coal fired boilers to neutralize sulfur trioxide (SO{sub 3}) to prevent stack gas opacity related emission problems and minimize air preheater corrosion and fouling. The objective of this project is to improve the purity and solids content of the by-product after it is separated from the gypsum. Several options were investigated to convert it into a more marketable or usable form. Test results and economic evaluations are reported during the different process steps needed to improve the product quality: (1) dissolving or washing out the gypsum impurity; (2) thickening the washed solids and using the overflow for makeup water within the FGD water balance; (3) finding the best means to dewater the washed, thickened slurry; and (4) repulp the dewatered cake into a stabilized slurry or dry it to powder. Flash drying the dewatered cake is compared to spray drying the thickened slurry. FGD Mg(OH){sub 2} is shown to have equal reactivity as an acid neutralization reagent on a Mg(OH){sub 2} molar basis to commercial Mg(OH){sub 2} products and other alkaline reagents. Its use for pH control in wastewater treatment is shown to produce a much smaller sludge volume than lime or sodium hydroxide.

  11. 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.

    2002-01-01T23:59:59.000Z

    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... packing in places. Finally, on May 15, 1998, researchers at ORNL completed a second test in their guarded- hot-box chamber. Several nationally known straw-bale home builders and Tav Commins of CEC oversaw construction of the walls and the testing...

  12. ACAA 2006 fall meeting

    SciTech Connect (OSTI)

    NONE

    2006-07-01T23:59:59.000Z

    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).

  13. 'The Overriding Demand for Energy Conservation in the Cement Industry' An Update

    E-Print Network [OSTI]

    Spellman, L. U.

    1981-01-01T23:59:59.000Z

    addi tives. While cement makes up only about 7 to 15 percent of the weight of concrete, it is 1:5y far the greatest contributor of energy content in the mixture. Cement, usually portland cement, is a product derived from pyro-processing calcareous... and argillaceous materials such as limestone and clay or shale into an intermediate fused material called clinker, which is subse quently ground together with a small amount of gypsum. Portland cement is the principal material produced by the U. S. cement...

  14. 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

    1980-01-01T23:59:59.000Z

    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... are needed to ach1eve energy self sufficiency for the Un1ted States. Advanced technology is needed to economically harness the cleanest source of alternate energy, the sun. However, another source of energy available us1ng present-day technology is coal...

  15. 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 Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsum Jump

  16. 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 Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsum JumpHydropower

  17. 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 Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsum

  18. 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 Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsumIranian Oil

  19. National Labs Use OpenEI to Showcase Capabilities | OpenEI Community

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsumIranian

  20. National Marine Fisheries Service | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home5b9fcbce19 No revision hasInformation Earth's HeatMexico: EnergyMithun JumpMuscoy,Jump9 CaseNatEl JumpGypsumIranianNational