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Waste reduction options for manufacturers of copper indium diselenide photovoltaic cells

Description: This paper identifies general waste reduction concepts and specific waste reduction options to be used in the production of copper indium diselenide (CIS) photovoltaic cells. A general discussion of manufacturing processes used for the production of photovoltaic cells is followed by a description of the US Environmental Protection Agency (EPA) guidelines for waste reduction (i.e., waste minimization through pollution prevention). A more specific discussion of manufacturing CIS cells is accompanied by detailed suggestions regarding waste minimization options for both inputs and outputs for ten stages of this process. Waste reduction from inputs focuses on source reduction and process changes, and reduction from outputs focuses on material reuse and recycling.
Date: March 1, 1994
Creator: DePhillips, M.P.; Fthenakis, V.M. & Moskowitz, P.D.
Partner: UNT Libraries Government Documents Department

Environmental and health aspects of CIS-module production, use and disposal

Description: Copper indium diselenide (CIS) is one of the most promising compounds in thin film technology. Since there is scant information available about environmental and health hazards, a study was initiated to characterize risks associated with the production, use and disposal of thin film photovoltaic modules. Data available from literature and developers of this technology contribute to an assessment of potential risks during production. In laboratory experiments the release of hazardous materials during operation caused by accidents or false handling and after disposal are simulated. In biological experiments the possible impact on living matter is established. These experiments comprise toxicity tests with aquatic organisms and rats representing mammals.
Date: December 31, 1994
Creator: Thumm, W.; Finke, A.; Neumeier, B.; Beck, B.; Kettrup, A.; Steinberger, H. et al.
Partner: UNT Libraries Government Documents Department

CIS photovoltaic technology. Annual technical report, January 12, 1996--January 11, 1997

Description: Thin film photovoltaic modules based on Cu(In,Ga)Se{sub 2} have been shown to possess attributes that should enable them to compete effectively with silicon-based modules, and that should ultimately allow realization of a much lower $/Wp cost figure. These attributes are stability, high efficiency, and low materials cost. Energy Photovoltaics has explored novel CIGS formation recipes that can be implemented on a unique pilot line constructed to coat substrates 4300 cm{sup 2} in area. One particular feature of this line is the use of proprietary linear sources capable of downwards evaporation. After experimentation with several types of recipe, a so-called {open_quotes}hybrid{close_quotes} process was found to simultaneously yield the desired combination of properties, namely good adhesion, device efficiency, uniformity, and reproducibility. The steps involve precursor formation, compound formation, and termination. Diagnostic techniques used to study and improve the CIGS films included spatial mapping of thickness, composition (using Auger analysis), resistance, V{sub oc} and I{sub sc}. The last three items are determined by quick tests designed to provide rapid feedback on plate quality. Problem areas were broken down and isolated through use of techniques involving substitution of different pieces of equipment for certain processing steps. For example, pilot line precursors were selenized in both the pilot line and smaller scale R&D equipment.
Date: June 1, 1997
Creator: Delahoy, A.E.; Britt, J.S. & Kiss, Z.J.
Partner: UNT Libraries Government Documents Department

Baseline Evaluation of Thin-Film Amorphous Silicon, Copper Indium Diselenide, and Cadmium Telluride for the 21st Century: Preprint

Description: This paper examines three thin-film PV technologies: amorphous silicon, cadmium telluride, and copper indium selenide. The purpose is to: (1) assess their status and potential; (2) provide an improved set of criteria for comparing these existing thin films against any new PV technological alternatives, and examining the longer-term (c. 2050) potential of thin films to meet cost goals that would be competitive with conventional sources of energy without any added value from the substantial environmental advantages of PV. Among the conclusions are: (1) today's thin films have substantial economic potential, (2) any new approach to PV should be examined against the substantial achievements and potential of today's thin films, (3) the science and technology base of today's thin films needs substantial strengthening, (4) some need for alternative technologies exists, especially as the future PV marketplace expands beyond about 30 GW of annual production.
Date: April 1, 1999
Creator: Zweibel, K.
Partner: UNT Libraries Government Documents Department

Processing and modeling issues for thin-film solar cell devices. Final report

Description: During the third phase of the subcontract, IEC researchers have continued to provide the thin film PV community with greater depth of understanding and insight into a wide variety of issues including: the deposition and characterization of CuIn{sub 1-x}Ga{sub x}Se{sub 2}, a-Si, CdTe, CdS, and TCO thin films; the relationships between film and device properties; and the processing and analysis of thin film PV devices. This has been achieved through the systematic investigation of all aspects of film and device production and through the analysis and quantification of the reaction chemistries involved in thin film deposition. This methodology has led to controlled fabrications of 15% efficient CuIn{sub 1-x}Ga{sub x}Se{sub 2} solar cells over a wide range of Ga compositions, improved process control of the fabrication of 10% efficient a-Si solar cells, and reliable and generally applicable procedures for both contacting and doping films. Additional accomplishments are listed below.
Date: November 1, 1997
Creator: Birkmire, R.W. & Phillips, J.E.
Partner: UNT Libraries Government Documents Department

Derived reference doses for three compounds used in the photovoltaics industry: Copper indium diselenide, copper gallium diselenide, and cadmium telluride

Description: Polycrystalline thin-film photovoltaic modules made from copper indium diselenide (CIS), copper gallium diselenide (CGS), and cadmium telluride (CdTe) arc nearing commercial development. A wide range of issues are being examined as these materials move from the laboratory to large-scale production facilities to ensure their commercial success. Issues of traditional interest include module efficiency, stability and cost. More recently, there is increased focus given to environmental, health and safety issues surrounding the commercialization of these same devices. An examination of the toxicological properties of these materials, and their chemical parents is fundamental to this discussion. Chemicals that can present large hazards to human health or the environment are regulated often more strictly than those that are less hazardous. Stricter control over how these materials are handled and disposed can increase the costs associated with the production and use of these modules dramatically. Similarly, public perception can be strongly influenced by the inherent biological hazard that these materials possess. Thus, this report: presents a brief background tutorial on how toxicological data are developed and used; overviews the toxicological data available for CIS, CGS and CdTe; develops ``reference doses`` for each of these compounds; compares the reference doses for these compounds with those of their parents; discusses the implications of these findings to photovoltaics industry.
Date: July 6, 1995
Creator: Moskowitz, P.D.; Bernholc, N.; DePhillips, M.P. & Viren, J.
Partner: UNT Libraries Government Documents Department

Determination of the Built-in Electric Field near Contacts to Polycrystalline CuInSe{sub 2} - Probing Local Charge Transport Properties by Photomixing

Description: The built-in electric field in polycrystalline CuInSe{sub 2} (CIS) near gold co-planar contacts was quantitatively revealed for the first time by the photomixing technique. A He-Ne laser beam was focused locally on the CIS sample near one of its contact. While both dc dark and photo-currents showed ohmic behavior, the high frequency ac current was non-zero for zero applied dc bias, which reveals a built-in electric field of {approx}1000V/cm. The capability of the photomixing technique to probe local charge transport properties is expected to be very useful for, e.g., the quantitative evaluation of the quality of ohmic contacts and the investigation of electric field induced p-n junction formation in CIS and related materials.
Date: November 19, 1998
Creator: Tang, Y.; Dong, S.; Sun, G. S.; Braunstein, R. & von Roedern, B.
Partner: UNT Libraries Government Documents Department

Summary of known linear and nonlinear optical properties of LiInS{sub 2}

Description: LiInS{sub 2} is a potentially useful crystal for cascaded parametric frequency conversion in the mid-IR. It is nearly noncritically phasematched for 1.064 {mu}m pumped, degenerate 2.12 {mu}m generation and 2 micron pumped generation of 3--5 {mu}m light. The nonlinear optical coefficients are 2{times} larger than those of KTP or KTA, while the transparency extends from 0.5--8 {mu}m. LiInS{sub 2} crystals are currently available in volumes up to 5 mm{sup 3}. This memo provides a brief summary of the current literature concerning the growth and linear and nonlinear optical properties of LiInS{sub 2}.
Date: February 24, 1994
Creator: Ebbers, C.
Partner: UNT Libraries Government Documents Department

Influence of Damp Heat on the Electrical, Optical, and Morphological Properties of Encapsulated CuInGaSe2 Devices: Preprint

Description: CuInGaSe2 (CIGS) devices, encapsulated with different backsheets having different water vapor transmission rates (WVTR), were exposed to damp heat (DH) at 85C and 85% relative humidity (RH) and characterized periodically to understand junction degradation induced by moisture ingress. Performance degradation of the devices was primarily driven by an increase in series resistance within first 50 h of exposure, resulting in a decrease in fill factor and, accompanied loss in carrier concentration and widening of depletion width. Surface analysis of the devices after 700-h DH exposure showed the formation of Zn(OH)2 from hydrolysis of the Al-doped ZnO (AZO) window layer by the moisture, which was detrimental to the collection of minority carriers. Minority carrier lifetimes observed for the CIGS devices using time resolved photoluminescence (TRPL) remained relatively long after DH exposure. By etching the DH-exposed devices and re-fabricating with new component layers, the performance of reworked devices improved significantly, further indicating that DH-induced degradation of the AZO layer and/or the CdS buffer was the primary performance-degrading factor.
Date: August 1, 2011
Creator: Sundaramoorthy, R.; Pern, F. J.; Teeter, G.; Li, J. V.; Young, M.; Kuciauskas, D. et al.
Partner: UNT Libraries Government Documents Department

Nanoscale Electronic Inhomogeneity in In_2Se_3 Nanoribbons Revealed by Microwave Impedance Microscopy

Description: Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides and chalcogenides, these microscopic phases are of great scientific and technological importance for research in hightemperature superconductors, colossal magnetoresistance effect, phase-change memories, and domain switching operations. Direct imaging on dielectric properties of these local phases,however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In{sub 2}Se{sub 3}) nanoribbons by near-field scanning microwave impedance microscopy. Multiple phases with local resistivity spanning six orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with {approx}100nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform quantitative sub-surface electronic study in a noninvasive manner. Finally, the phase change memory function in In{sub 2}Se{sub 3} nanoribbon devices can be locally recorded with big signal of opposite signs.
Date: June 2, 2010
Creator: Lai, K.J.
Partner: UNT Libraries Government Documents Department

Siemens solar CIS photovoltaic module and system performance at the National Renewable Energy Laboratory

Description: This paper evaluates the individual module and array performance of Siemens Solar Industries` copper indium diselenide (CIS) polycrystalline thin-film technology. This is accomplished by studying module and array performance over time. Preliminary temperature coefficients for maximum power, maximum-power voltage, maximum-power current, open-circuit voltage, short-circuit current, and fill factor are determined at both the module and array level. These coefficients are used to correct module/array performance to 25{degrees}C to evaluate stability. We show that CIS exhibits a strong inverse correlation between array power and back-of-module temperature. This is due mainly to the narrow bandgap of the CIS material, which results in a strong inverse correlation between voltage and temperature. We also show that the temperature-corrected module and array performance has been relatively stable over the evaluation interval (=2 years).
Date: May 1, 1996
Creator: Strand, T.R.; Kroposki, B.D. & Hansen, R.
Partner: UNT Libraries Government Documents Department

Understanding and managing health and environmental risks of CIS, CGS, and CdTe photovoltaic module production and use: A workshop

Description: Environmental, health and safety (EH&S) risks presented by CIS, CGS and CdTe photovoltaic module production, use and decommissioning have been reviewed and discussed by several authors. Several EH&S concerns exit. The estimated EH&S risks are based on extrapolations of toxicity, environmental mobility, and bioavailability data for other related inorganic compounds. Sparse data, however, are available for CIS, CGS or CdTe. In response to the increased interest in these materials, Brookhaven National Laboratory (BNL) has been engaged in a cooperative research program with the National Renewable Energy Laboratory (NREL), the Fraunhofer Institute for Solid State Technology (IFT), the Institute of Ecotoxicity of the GSF Forschungszentrum fair Umwelt und Gesundheit, and the National Institute of Environmental Health Sciences (NIEHS) to develop fundamental toxicological and environmental data for these three compounds. This workshop report describes the results of these studies and describes their potential implications with respect to the EH&S risks presented by CIS, CGS, and CdTe module production, use and decommissioning.
Date: April 28, 1994
Creator: Moskowitz, P.D.; Zweibel, K. & DePhillips, M.P.
Partner: UNT Libraries Government Documents Department

Processing of CuInSe{sub 2}-based solar cells: Characterization of deposition processes in terms of chemical reaction analyses. Phase I annual report, 6 May 1995--5 May 1996

Description: An interdisciplinary team of five graduate students and four faculty have made considerable progress during Phase I of this program. The objective of this initiative is to develop a high-rate processing sequence to produce device-quality thin films of CI(G)S(Se). A comprehensive CI(G)S(Se) device fabrication capability is being established that includes thermal evaporation and plasma assisted deposition of CI(G)S(Se), rapid thermal processing, DC sputtering of both undoped and doped ZnO, CBD and MOCVD of CdS, and rf sputtering of Mo. Insight into the materials processing issues is being addressed through assessment of the thermochemistry and phase equilibria of the CI(G)S(Se) system, single crystal growth studies, investigation of Na effects on the growth, and detailed materials characterization.
Date: April 1, 1997
Creator: Anderson, T.
Partner: UNT Libraries Government Documents Department

Research on polycrystalline thin-film submodules based on CuInSe{sub 2} materials. Final technical report, 14 December 1995--31 December 1996

Description: This report describes the progress made at Solarex for both device and module efficiencies from the inception of the CIS research program to the present. A rapid improvement in efficiency is apparent, culminating in the fabrication of a 15.5%-efficient device (total area) and a 13%-efficient submodule (aperture area). The device represents the highest efficiency device measured by NREL for any industrial source at that time. The module represented a new world record for any thin-film module at the time of its measurement. The factors leading to these results included improvements in absorber layer quality, transparent contacts, scribing and module formation processes. Other elements critical to the commercialization of CIS-based photovoltaics were also successfully attacked, including reduction of absorber deposition times into the range of 10 to 20 minutes and the successful scale-up of the absorber deposition process to greater than 500 cm{sup 2}. Other requisite processes saw continued development, such as a rapid, low-cost method for transparent window deposition. Subsequent to the demonstration of 13% module efficiency, scribing techniques were further improved that resulted in a reduction in shunt losses and higher module fill factor. This improvement, and the concomitant gain in fill factor, would yield efficiencies approaching 14% on modules having a short-circuit and open-circuit voltage comparable to the record module.
Date: April 1, 1997
Creator: Arya, R.; Fogleboch, J.; Kessler, J.; Russell, L.; Skibo, S. & Wiedeman, S.
Partner: UNT Libraries Government Documents Department

A low-cost approach to fabrication of multinary compounds for energy-related applications

Description: Non-vacuum electrodeposition and electroless deposition techniques with a potential to prepare large-area uniform precursor films using low-cost source materials and low-cost capital equipment are very attractive for the growth of compound materials for superconductors and photovoltaic applications. In the first part, a low-cost electrodeposition (ED) method will be discussed for fabrication of high-temperature Tl-oxide-based superconductors. In the second part, electrodeposition and electroless deposition of semiconductor Cu-In-Ga-Se thin films will be discussed.
Date: January 3, 2000
Creator: Bhattacharya, R.N. & Deb, S.K.
Partner: UNT Libraries Government Documents Department

Preferred orientation in polycrystalline Cu(In,Ga)Se{sub 2} and its effect on absorber thin-films and devices

Description: The purpose of this work is to investigate physical properties of Cu(In,Ga)Se{sub 2} polycrystalline thin-films exhibiting a high degree of preferred orientation. Specifically, by using Na-free Cu(In,Ga)Se{sub 2} thin-films, it is intended to experimentally determine differences (if any) between films with a (110/102)-preferred orientation and films with a (112)-preferred orientation. The approach to the problem is a systematic comparative analysis of film and device properties in which the most significant variable is the preferred orientation of the Cu(In,Ga)Se{sub 2} polycrystalline absorbers. To complement the results of Na-free absorbers and devices, a microstructural analysis is presented on (110)-oriented high efficiency Cu(In,Ga)Se{sub 2} absorbers that are grown on standard Mo-coated soda-lime glass substrates.
Date: May 15, 2000
Creator: Contreras, M. A.; Jones, K. M.; Gedvilas, L. & Matson, R.
Partner: UNT Libraries Government Documents Department

Novel two-stage selenization methods for fabrication of thin-film CIS cells and submodules. Final subcontract report, March 1, 1993--March 31, 1995

Description: This is the Phase 11 Final Technical Report of the subcontract titled {open_quotes}Novel Two-Stage Selenization Methods for Fabrication of Thin Film CIS Cells and Submodules.{close_quotes} The general objectives of the program are the development of a cost-effective, large-area process for CIS film deposition, optimization of the various layers forming the CIS device structure, and fabrication of high efficiency submodules using these optimized device components. During this research period, growth parameters of ZnO window layers were varied to optimize their electrical and optical properties. Investigation of the chemical interactions between the glass substrates, Mo layers and the selenization atmosphere revealed that the nature of the glass/Mo substrate greatly influenced the quality of the solar cells fabricated on them. Moderate amounts of sodium diffusing from the soda-lime glass substrate into the CIS film improved the efficiencies of the solar cells fabricated on such films. Mo layers allowing excessive Na diffusion through them, on the other hand, reacted excessively with the H{sup 2}Se environment and deteriorated the solar cell performance. Addition of Ga into the CIS layers by the two-stage selenization technique yielded graded absorber structures with higher Ga content near the Mo/absorber interface. Cu-rich CIS layers were grown with grain sizes of larger than 5 {mu}m. In the Phase I Annual Report large area CIS submodules with efficiencies of about 3% were reported. During the present Phase II program 1 ft{sup 2} size CIS submodule efficiency was improved to 7%. Smaller area submodules with efficiencies as high as 9.79% were also fabricated using CIS layers obtained by the H{sub 2}Se selenization method. The processing yield of the devices based on a non-vacuum CIS deposition approach was improved and solar cells with efficiencies greater than 10% were fabricated.
Date: June 1, 1995
Creator: Basol, B.; Kapur, V.; Halani, A.; Leidholm, C. & Minnick, A.
Partner: UNT Libraries Government Documents Department

Processing and modeling issues for thin-film solar cell devices: Annual subcontract report, January 16, 1995 -- January 15, 1996

Description: The overall mission of the Institute of Energy Conversion is the development of thin film photovoltaic cells, modules, and related manufacturing technology and the education of students and professionals in photovoltaic technology. The objectives of this four-year NREL subcontract are to advance the state of the art and the acceptance of thin film PV modules in the areas of improved technology for thin film deposition, device fabrication, and material and device characterization and modeling, relating to solar cells based on CuInSe{sub 2} and its alloys, on a-Si and its alloys, and on CdTe. In the area of CuInSe{sub 2} and its alloys, EEC researchers have produced CuIn{sub 1-x}GaxSe{sub 2} films by selenization of elemental and alloyed films with H{sub 2}Se and Se vapor and by a wide variety of process variations employing co-evaporation of the elements. Careful design, execution and analysis of these experiments has led to an improved understanding of the reaction chemistry involved, including estimations of the reaction rate constants. Investigation of device fabrication has also included studies of the processing of the Mo, US and ZnO deposition parameters and their influence on device properties. An indication of the success of these procedures was the fabrication of a 15% efficiency CuIn{sub 1-x}GaxSe{sub 2} solar cell.
Date: August 1, 1996
Creator: Birkmire, R.W.; Phillips, J.E.; Buchanan, W.A.; Eser, E.; Hegedus, S.S.; McCandless, B.E. et al.
Partner: UNT Libraries Government Documents Department

CIS photovoltaic technology. Annual technical report, January 12, 1995--January 11, 1996

Description: EPV`s overall strategy in developing CIGS photovoltaic technology has been to define and construct a flexible set of large area vacuum deposition equipment and to explore CIGS formation recipes that can be implemented on this equipment. This is the inverse of the conventional approach in which manufacturing techniques are sought that can reproduce a high efficiency laboratory scale process over large areas. A feature of this equipment is the use of proprietary linear sources capable of downwards evaporation. Using recipes generated within this program, CIGS cells with efficiencies up to 13.9% were prepared by EPV under a separate CRADA with NREL. Entirely within this program, an aperture area efficiency of 9.6% was achieved for a laminated submodule of area 135.2 cm{sup 2}. Considerable effort has gone into the preparation and characterization of CIGS prepared on substrates measuring 96.5 cm x 44.5 cm, and good compositional uniformity has been achieved along both the short and long directions of the plate. Despite this, the material has not yet achieved the efficiency levels demonstrated in smaller scale equipment, and recipe development is ongoing. As part of a program to eliminate, if possible, the use of CdS, alternative buffer layers such as InSe, In{sub x}S{sub y}, and ZnSe have been explored, and, to gain insight into junction formation, CdSe. Of these compounds, ZnSe has shown the most promise, and further experiments are being conducted to optimize material and device properties.
Date: June 1, 1996
Creator: Delahoy, A.E.; Britt, J.S. & Gabor, A.M.
Partner: UNT Libraries Government Documents Department

Pulsed laser ablation growth and doping of epitaxial compound semiconductor films

Description: Pulsed laser ablation (PLA) has several characteristics that are potentially attractive for the growth and doping of chemically complex compound semiconductors including (1) stoichiometric (congruent) transfer of composition from target to film, (2) the use of reactive gases to control film composition and/or doping via energetic-beam-induced reactions, and (3) low-temperature nonequilibrium phase formation in the laser-generated plasma ``plume.`` However, the electrical properties of compound semiconductors are far more sensitive to low concentrations of defects than are the oxide metals/ceramics for which PLA has been so successful. Only recently have doped epitaxial compound semiconductor films been grown by PLA. Fundamental studies are being carried out to relate film electrical and microstructural properties to the energy distribution of ablated species, to the temporal evolution of the ablation pulse in ambient gases, and to beam assisted surface and/or gas-phase reactions. In this paper the authors describe results of ex situ Hall effect, high-resolution x-ray diffraction, transmission electron microscopy, and Rutherford backscattering measurements that are being used in combination with in situ RHEED and time-resolved ion probe measurements to evaluate PLA for growth of doped epitaxial compound semiconductor films and heterostructures. Examples are presented and results analyzed for doped II-VI, I-III-VI, and column-III nitride materials grown recently in this and other laboratories.
Date: December 1995
Creator: Lowndes, D. H.; Rouleau, C. M.; Geohegan, D. B.; Budai, J. D.; Poker, D. B.; Puretzky, A. A. et al.
Partner: UNT Libraries Government Documents Department

Numericl modeling of graded band gap CIGS solar cells

Description: The high efficiency reported recently by NREL for CIGS solar cells demonstrates the potential of band gap grading in producing high efficiency thin film solar cells. In order to reap the full benefits of this design strategy, a clear understanding of the fundamental device physics of these structures is needed. The purpose of this paper is to examine the role grading of the band gap plays in achieving high conversion efficiencies. To aid in this examination, a detailed numerical device simulation program, ADEPT, is used.
Date: December 31, 1994
Creator: Gray, J.L. & Lee, Youn Jung
Partner: UNT Libraries Government Documents Department

Thermodynamic properties of SeS

Description: Mass-spectrometry and Knudsen effusion experiments were used to study the equilibrium partial pressure of SeS formed by reaction of S/sub 2/ and Se/sub 2/ which were produced by thermally decomposing a mixture of In/sub 2/S/sub 3/ and In/sub 2/Se/sub 3/ in a Knudsen effusion cell. The heat of formation of SeS(g) was determined by the second law method to be -0.6 +- 3 kcal/mole. The entropy of formation of SeS(g) was calculated from spectrographic data in Ahmed and Barrow to be 1.5 cal/degree-mole at 298/sup 0/K.
Date: December 1, 1977
Creator: Huang, M.D.
Partner: UNT Libraries Government Documents Department

New plasma source of hydrides for epitaxial growth. Final subcontract report, 15 April 1991--3 September 1993

Description: This report describes a novel plasma-activated selenium source that was developed during the course of this subcontract and which is significantly different than any other heretofore reported in the scientific literature. It involves microwave excited, magnetically confined plasma sources that are intended to operate under electron cyclotron resonance (ECR) conditions at 2.455 GHz. This source is designed to excite and dissociate the molecular vapor evaporating or subliming from a heated solid or liquid reservoir. It can combine an effusion cell vapor flux with a stream of hydrogen or helium gas, enabling the in-situ generation of hydrides for use in low-pressure growth techniques where long mean free paths are desirable. Experiments were conducted to demonstrate a stable discharge within the source, and measures were identified to improve its operational characteristics. Application of this novel source is anticipated to enable a low-temperature, safe process for the growth of high-quality epitaxial compound semiconductor films. This reduction of epitaxial growth temperatures may enable the fabrication of novel photovoltaic devices that have heretofore been impossible due to the deleterious effects of interdiffusion at heterointerfaces resulting from the high temperatures required to grow adequate quality material using conventional processes.
Date: May 1, 1994
Creator: Stanbery, B. J.
Partner: UNT Libraries Government Documents Department

Polycrystalline thin films FY 1992 project report

Description: This report summarizes the activities and results of the Polycrystalline Thin Film Project during FY 1992. The purpose of the DOE/NREL PV (photovoltaic) Program is to facilitate the development of PV that can be used on a large enough scale to produce a significant amount of energy in the US and worldwide. The PV technologies under the Polycrystalline Thin Film project are among the most exciting ``next-generation`` options for achieving this goal. Over the last 15 years, cell-level progress has been steady, with laboratory cell efficiencies reaching levels of 15 to 16%. This progress, combined with potentially inexpensive manufacturing methods, has attracted significant commercial interest from US and international companies. The NREL/DOE program is designed to support the efforts of US companies through cost-shared subcontracts (called ``government/industry partnerships``) that we manage and fund and through collaborative technology development work among industry, universities, and our laboratory.
Date: January 1, 1993
Creator: Zweibel, K.
Partner: UNT Libraries Government Documents Department