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Amorphous and Thin-Film Silicon

Search the Thin-film Resource Database for more articles, news, and reports.

Amorphous silicon (a-Si) was heralded as the "only" thin-film PV material in the 1980s; a decade later, many people wrote it off for its instability and low efficiencies. Multijunction cell configurations have helped solve these problems. In the near term, look for modules with 6% to 8% efficiencies, as well as the construction of multi-megawatt a-Si facilities.

Press Releases, Articles, Pictures/Tables/Figures, Other Items

Journal Articles

Conference Papers

Post Date	05/30/2008
Title	THE ROLE OF POLYCRYSTALLINE THIN-FILM PV TECHNOLOGIES IN COMPETITIVE PV MODULE MARKETS
Link	(PDF 351 KB) Download Acrobat Reader.
Authors	B. Von Roedern, H. S. Ullal
Description	This paper discusses the developments in thin-film PV technologies. It provides an outlook on future commercial module efficiencies achievable based on today?s knowledge about champion cell performance. It also provides a relative cost comparison of thin-film and wafer/ribbon based Si PV modules. In 2007, about 65% of the modules produced in the US were thin-film modules when amorphous silicon modules are also considered.
Venue	Presented at the 33rd IEEE PVSC Conference, San Diego, CA 05/12-16/2008
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2008

Post Date	09/28/2007
Title	THIN FILM CIGS AND CDTE PHOTOVOLTAIC TECHNOLOGIES: COMMERCIALIZATION, CRITICAL ISSUES, AND APPLICATIONS
Link	(PDF 725 KB) Download Acrobat Reader.
Authors	H. S. Ullal, B. Von Roedern
Description	We report here on the major commercialization aspects of thin-film photovoltaic (PV) technologies based on CIGS and CdTe (a-Si and thin-Si are also reported for completeness on the status of thin-film PV). Worldwide silicon (Si) based PV technologies continues to dominate at more than 94% of the market share, with the share of thin-film PV at less than 6%. However, the market share for thin-film PV in the United States continues to grow rapidly over the past several years and in CY 2006, they had a substantial contribution of about 44%, compared to less than 10% in CY 2003. In CY 2007, thin-film PV market share is expected to surpass that of Si technology in the United States. Worldwide estimated projections for CY 2010 are that thin-film PV production capacity will be more than 3700 MW. A 40-MW thin-film CdTe solar field is currently being installed in Saxony, Germany, and will be completed in early CY 2009. The total project cost is Euro 130 million, which equates to an installed PV system price of Euro 3.25/-watt averaged over the entire solar project. This is the lowest price for any installed PV system in the world today. Critical research, development, and technology issues for thin-film CIGS and CdTe are also elucidated in this paper.
Venue	22nd EC PVSEC, Milano, Italy Sep 3-7, 2007, paper presented
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2007

Post Date	01/03/2008
Title	EFFECT OF SURFACE PASSIVATION ON SI HETEROJUNCTION AND INTERDIGITATED BACK CONTACT SOLAR CELLS
Link	(PDF 69 KB) Download Acrobat Reader.
Authors	U. Das, R. W. Birkmire
Description	Excellent surface passivation (?eff > 1 msec) and high VOC in SHJ cells are achieved by both RF and DC plasma process with hydrogen dilution. Any epitaxial / nanocrystalline growth of i-layer reduces ?eff and cell VOC. The structure of deposited thin Si:H layers strongly depend on the Si substrate orientation. The front emitter SHJ cell efficiency approaching 19% with VOC of 694 mV was achieved on textured Cz wafer using DC plasma deposited i-layer. The exploratory heterojunction cells in IBC structure reveals importance of surface passivation in the rear to achieve high VOC (683 mV) and JSC but demands further optimization of i-layer for improved carrier transport across it and cell FF.
Venue	Institute of Energy Conversion, U. Delaware. Presented at the 17th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes (Vail, Cascade Resort, Vail, CO, Aug. 5 ? 8, 2007).
Source	University of Delaware
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	08/05/2007

Post Date	05/30/2007
Title	METASTABLE DEFECT FORMATION IN TRITIATED A-SI:H
Link	(MS Word 128 KB)
Authors	G. A. Williams, P. C. Taylor
Description	We have shown direct evidence for the diffusion of hydrogen to heal the production of a large density (approximately 10^21 cm^-3) of silicon dangling bonds in tritiated a-Si:H,T. Some of the network healing mechanisms, which follow tritium decay, are essentially athermal and occur even at very low temperatures.
Venue	paper from the DOE Solar technology Review Meeting, Denver, CO 04/17-19/2007
Source	University of Utah
Document Type	Conference Papers (Word document)
Resource Date	04/2007

Post Date	10/11/2007
Title	DEPENDENCE OF THE ELECTRONIC PROPERTIES OF HOT-WIRE CVD AMORPHOUS SILICON-GERMANIUM ALLOYS ON OXYGEN IMPURITY LEVELS
Link	(PDF 113 KB) Download Acrobat Reader.
Authors	J. D. Cohen, Y. Xu, A. H. Mahan, H. M. Branz, S. Datta
Description	We report the effects of intentionally introducing up to ~ 5�10^20/cm^3 oxygen impurities into hydrogenated amorphous silicon-germanium alloys (of roughly 30at.% Ge) grown by the hot-wire chemical vapor deposition (HWCVD) method. Deep defect densities determined by drive-level capacitance profiling (DLCP) indicated a modest increase with increasing oxygen content (up to a factor of 3 at the highest oxygen level). Transient photocapacitance (TPC) spectra indicated a clear spectral signature for an optical transition between the valence band and an empty defect level, with an optical threshold around 1.3-1.4eV. This feature becomes stronger as the concentration of oxygen is increased. This transition results in a negative contribution to the TPC signal, and this initially led us to believe that the bandtail for the higher oxygen samples was much narrower than it actually is. Surprisingly, this additional oxygen related defect level appears to have only a very minor effect upon the estimated minority carrier collection fraction. The effects of light-induced degradation upon some of these oxygen contaminated samples were also examined in detail. We infer the existence of a significant thermal barrier to explain the observed spectral signature of this oxygen impurity defect.
Venue	MRS Spring Meeting 04/2007, San Francisco
Source	University of Oregon
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	04/2007

Post Date	04/30/2007
Title	OUTDOOR MONITORING AND HIGH VOLTAGE BIAS TESTING OF THIN FILM PV MODULES
Link	(MS Word 64 KB)
Author	N. G. Dhere
Description	Limitations of accelerated testing to predict all possible degradation modes and mechanisms in the photovoltaic PV modules necessitate that actual outdoor monitoring and testing of PV modules be performed out-doors. For this reason, thin film PV modules from leading US thin film PV manufacturers namely, First Solar (Glass/CdTe/Glass), Shell Solar Glass/CIS/Glass), Shell Solar New (Glass/CIGS/Glass), United Solar (a-Si:H on flexible substrate), Energy Photovoltaics (Glass/a-Si:H/Glass) and Global Solar (CIS on flexible substrate) with additional one crystalline silicon module are being tested. The goal is to assess their performance in the hot and humid climate of Florida and to correlate the PV performance with the meteorological parameters namely, solar irradiance, temperature, relative humidity, wind speed, etc. Statistical data analysis of the recorded data is carried out on a daily basis and on a monthly basis with PVUSA type regression analysis. Current-voltage characteristics (I-V) of module arrays taken on a regular basis complement the results obtained with continuous data monitoring. Moreover, high voltage bias testing of the modules is carried out to study behavior of leakage currents and detect any packaging material and processing flaws and consequently the module reliability.
Venue	DOE Solar Technology Review Meeting, Denver, CO, 4/17-19/2007
Source	FLorida Solar Energy Center
Document Type	Conference Papers (Word document)
Resource Date	03/2007

Post Date	10/26/2006
Title	BOS COST SAVINGS NEEDS AND POTENTIAL FOR LARGE SCALE GROUND BASED PV SYSTEMS UNTIL 2010
Link	(PDF 495 KB) Download Acrobat Reader.
Author	M. Bachler
Description	More and more large scale ground based systems were implemented with thin-film modules in the past years in Germany. Based on module pricing thin film modules appear to be very attractive for this type of application. However there are quite significant differences in balance-of-system (BOS) costs within different c-Si and thin film (TF) module types, which have a high impact on total system costs. The BOS cost portion is significantly higher for systems with TF modules compared to c-Si modules. Existing c-Si modules and BOS components were developed and optimized to achieve cost savings in the past decades already a lot. TF modules as well as the related BOS components are at the very beginning of this development so the cost saving potential ? especially for BOS costs is considered to be significantly higher for TF module based systems. Since a 6.5% degression in the feed-in tariff is required in the German EEG for ground based systems a high cost reduction pressure is imposed on total system costs. The results of BOS cost savings achieved already will be demonstrated for a sample thin-film module.
Venue	Dresden World Conference
Source	Phonix SonnenStrom AG
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2006

Post Date	06/02/2006
Title	ULTRA-LIGHT AMORPHOUS SILICON CELL FOR SPACE APPLICATIONS
Link	(PDF 140 KB) Download Acrobat Reader.
Author	N. Wyrsch
Description	For space applications, solar cells should be optimized for highest power density rather than for highest efficiency. In this context, relatively low efficiency thin-film solar cell may well surpass multi-junction III-V based solar cells if they can be made thin enough. In thin-film solar cells the power density is mostly limited by the substrate. The introduction of ultra-thin polymeric substrates is the key for decreasing the cell mass. In this work, a very thin polyimide film LaRC?-CP1 was used as substrate or superstrate for amorphous silicon solar cell fabrication. CP1 films were either fixed on a glass carrier or spin coated onto a glass carrier coated with a release agent. By depositing amorphous silicon cells on 6 �m thick CP1 films, a power density of 2.9 W/g under AM1.5g and of 3.9 W/g (estimated) under AM0 illumination spectra was achieved, in substrate (n-i-p) configuration (for a cell area of ca. 0.25 cm2).
Venue	4th WCPEC May 2006
Source	University of Neuchatel
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	05/22/2006
Title	TECHNOLOGY CHOICE AND THE COST REDUCTION POTENTIAL OF PHOTOVOLTAICS
Link	(PDF 116 KB) Download Acrobat Reader.
Authors	J. E. Trancik, K. Zweibel
Description	We use a combination of system component analyses and individual experience curves for crystalline silicon (x-Si) modules, thin-film (TF) modules, and the balance of system (BOS) components, to compare future growth scenarios for photovoltaics (PV). The growth rates of TF and x-Si technologies are varied, while overall PV growth is held constant at 30%. For each of these scenarios, we estimate the total investment required for PV to reach a break-even point with fossil fuel based generation; and we investigate the intrinsic/lowest achievable costs from an analysis of potential materials, processing, and efficiency improvements. Our results show that a high growth rate (50 to 70% per year) of new technologies with low intrinsic costs could decrease the total investment required to reach break-even by up to 70 billion USD, as compared to a scenario where x-Si continues to dominate the market. Furthermore, the system component analysis indicates that existing TF modules can reach the low cost levels assumed in the experience curve model. These results suggest that the future growth of photovoltaics (PV) is dependent on which PV technologies grow most rapidly. New, low intrinsic cost technologies that are successfully able to enter the market could dramatically increase the potential for PV to become a globally significant energy conversion technology within the next two decades.
Venue	Trancik and Zweibel, WCPEC-4 2006
Sources	National Renewable Energy Laboratory; Santa Fe Institute
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	09/19/2006
Title	CSG-1: MANUFACTURING A NEW POLYCRYSTALLINE SILICON PV TECHNOLOGY
Link	(PDF 378 KB) Download Acrobat Reader.
Author	P. A. Basore
Description	Crystalline Silicon on Glass (CSG) is a polycrystalline silicon PV (photovoltaic) technology that requires less than two micrometers of silicon thickness. At the time of this writing in April 2006, production of CSG solar panels is just beginning in a full-scale factory known as CSG-1. It was only 14 months ago, in February 2005, that groundbreaking for this factory occurred. At that time, the technology had only been demonstrated in 900-cm laboratory samples. This article discusses some of the challenges faced in taking a new PV technology from R&D into production in such a short period of time. Photos of the equipment used for each of the key steps are shown and the experience of commissioning the process is discussed.
Venue	Presented at the 4th World Conference on Photovoltaic Energy Conversion, Waikoloa, Hawaii, 9 May 2006
Source	CSG Solar
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/2006

Post Date	12/23/2005
Title	PATHWAYS TO THIN FILM POLYCRYSTALLINE SILICON USING AMORPHOUS SILICON PRECURSORS
Link	(MS Word 482 KB)
Authors	O. Ebil, S. S. Hegedus, R. W. Birkmire
Description	Multiple pathways to producing large grain Si films on low cost substrates have been investigated. A-Si films deposited by Hot Wire CVD (HWCVD) on glass have been crystallized by in-situ Aluminum-induced crystallization (AIC). The AIC occurs during the a-Si growth at 430�C eliminating the need for a separate AIC step. Both the Si/Al thickness ratio and Si thickness are critical to give optimum poly-Si films. Maximum a-Si and Al thicknesses of 0.6 and 0.5 �m resulted in continuous films with grains ~10 �m.
Venue	Solar Technology Review Meeting, Denver, CO, 11/7-10/2005
Source	University of Delaware
Document Type	Conference Papers (Word document)
Resource Date	11/2005

Post Date	10/20/2005
Title	A REVIEW OF RISKS IN THE SOLAR ELECTRIC LIFE-CYCLE
Link	(PDF 642 KB) Download Acrobat Reader.
Authors	V. Fthenakis, H. C. Kim
Description	Early studies of risks in the life cycle of solar electric technologies do not represent their current stage of development. Our study updates the data used in previous studies and also accounts for the full life-cycle of photovoltaics. We show that the non-radiological risks of the solar electric- and nuclear-life cycles are approximately equal. This contradicts the conclusions of some earlier studies according to which the former presented much greater occupational and public non-radiological risks than the latter.
Venue	Brussels 2005
Source	Brookhaven National Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2005

Post Date	10/20/2005
Title	FABRICATION AND CHARACTERIZATION OF TRIPLE-JUNCTION AMORPHOUS SILICON BASED SOLAR CELL WITH NANOCRYSTALLINE SILICON BOTTOM CELL
Link	(PDF 147 KB) Download Acrobat Reader.
Authors	X. Deng, et al.
Description	Highlights of recent research activities and results on the project ?The Fabrication and Characterization of High-efficiency Triple-junction a-Si Based Solar Cells? at the University of Toledo (UT) under the NREL TFPP Program are briefly reviewed in this paper. Using VHF PECVD, new growth regimes have been established at UT for preparation of high quality a-Si, a-SiGe and nc-Si i-layers at rates of 2-15 �/s. Initial efficiencies of 7.2%, for VHF nc-Si n-i-p single-junction solar cells, 9.6% for a-Si/nc-Si tandem cells, and 11.0% for a-Si/a- SiGe/nc-Si triple cells have all been achieved. The progress of our research on high-rate nc-Si deposition using high pressure (8 Torr) PECVD is also reported.
Venue	DOE Solar Program Review 2005, Denver
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2005

Post Date	09/13/2005
Title	AMORPHOUS SILICON- FROM DOPING TO MULTI-BILLION DOLLAR APPLICATIONS.
Link	(PDF 342 KB) Download Acrobat Reader.
Author	A. Madan
Description	In this paper, we recount the history leading up to the landmark paper by Spear and LeComber in 1975, which showed, contrary to thought at the time, that it was indeed possible to incorporate substitutionally pentavalent and trivalent impurities into a tetrahedral amorphous semiconductor. This work provided the basis for a multi-billion dollar business with products which are ubiquitous.
Venue	Invited talk: presented at ICANS21, Lisbon, Portugal, Sept. 2005
Source	MVSystems
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	09/2005

Post Date	07/26/2005
Title	DEVICE PERFORMANCES AND SIMULATIONS FOR SEVERAL KINDS OF LARGE-SCALE THIN FILM SILICON SOLAR CELL MODULES -INTRODUCTION OF SUPER SEE-THROUGH THIN FILM SOLAR CELL MODULE AND APPLICATIONS
Link	(PDF 219 KB) Download Acrobat Reader.
Author	Kishimoto
Description	We fabricated large-scale thin film silicon solar cell modules with amorphous silicon and micro-crystallized p-i-n structure on a TCO film by a PECVD system. We also developed the device simulator for conventional and see-through thin film solar cell modules, and simulated their cell performances in order to estimate the influences of some electrical factors such as a series resistance, a shunt pass and its distribution. We confirmed the initial conversion efficiency of 12.1%(Pm 58.4W, Im 1.22A, Voc 67.4V, F.F. 0.711), corresponding to about 11% stabilized conversion efficiency and the initial conversion efficiency of 10.0%(Pm 48.1W, Im 1.05A, Voc 66.4V, F.F. 0.717) of a super see-through thin film solar module with 10% transparency with the same substrate size of 560x925mm.
Venue	Barcelona, PVSC
Source	Sharp
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/13/2005
Title	IMPLICATIONS OF EUROPEAN ENVIRONMENTAL LEGISLATION FOR PHOTOVOLTAIC SYSTEMS
Link	(PDF 434 KB) Download Acrobat Reader.
Authors	M. J. De Wild-Scholten, K. Wambach, E. A. Alsema, A. Jager-Waldau
Description	An overview is given of European environmental legislation which is effective now or proposed and which may have implications for the photovoltaic industry. The focus will be on legislation, which has been implemented already in national law, like the WEEE (waste electrical and electronic equipment)- and ROHS Reach (Registration, Evaluation, Authorisation and Restriction of Chemicals), F-gases (regulation on certain fluorinated greenhouse gases) and EuP (eco-design requirements for energy-using products). A change of the module design, with the research, development, implementation and certification necessary to be able to produce photovoltaic systems that comply with such legislation, may be very time-consuming and expensive. Therefore a pro-active approach by the PV community is desirable. Environmental life cycle thinking and eco-design is becoming increasingly important as part of the European product and waste policy and will have its impact on the PV industry as well. Design-for-recycling must be encouraged to allow for an easy, cost-effective disassembly, with a high retrieval of for instance the precious crystalline silicon solar cells. A closed production cycle, i.e. guaranteed take back system, would probably prevent the commission as well as member states to impose legislative measures.
Venue	20th European PVSC Barcelona
Sources	Deutsche Solar; Energy Research Centre of the Netherlands
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2005

Post Date	06/29/2005
Title	NREL PAPERS FOR THE PVSC IN ORLANDO, 2005
Link	(MS Word 41 KB)
Author	N/A
Description	Links to about 20 papers in CIS, CdTe, a-Si, thin Si and reliability.
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	06/2005

Post Date	05/09/2005
Title	TEMPERATURE-DEPENDENT OPEN-CIRCUIT VOLTAGE MEASUREMENTS AND LIGHT-SOAKING INHYDROGENATED AMORPHOUS SILCON SOLAR CELLS
Link	(MS Word 334 KB)
Authors	S. Guha, J. Liang, E. A. Schiff, B. Yan, J. Yang
Description	We present temperature-dependent measurements of the open-circuit voltage VOC(T) in hydrogenated amorphous silicon pin solar cells prepared at United Solar. At room-temperature and above, VOC measured using near-solar illumination intensity differs by as much as 0.04 V for the as-deposited and light-soaked states; the values of VOC for the two states converge below 250 K. Models for VOC based entirely on recombination through deep levels (dangling bonds) do not account for the convergence effect. The convergence is present in a model that assumes the recombination traffic in the as-deposited state involves only bandtails, but which splits the recombination traffic fairly evenly between bandtails and defects for the light-soaked state at room-temperature. Recombination mechanisms are important in understanding light-soaking, and the present results are inconsistent with models that assume an immediate connection between a recombination process and defect generation.
Venue	MRS Spring Meeting 2005, San Francisco, CA, Symposium A
Sources	Syracuse University; Uni-Solar Ovonic
Document Type	Conference Papers (Word document)
Resource Date	04/2005

Post Date	05/09/2005
Title	LIGHT-SOAKING EFFECTS ON THE OPEN-CIRCUIT VOLTAGE OF A-SI:H SOLAR CELLS
Link	(MS Word 938 KB)
Authors	S. Guha, J. Liang, E. A. Schiff, B. Yan, J. Yang
Description	We present measurements on the decline of the open-circuit voltage VOC in a-Si:H solar cells during extended illumination (light-soaking). We used a near-infrared laser that was nearly uniformly absorbed in the intrinsic layer of the cell. At the highest photogeneration rate (about 2x1021 cm-3), a noticeable decline (0.01 V) occurred within about 10 minutes; VOC stabilized at 0.04 V below its initial value after about 200 hours. We found that both the kinetics and the magnitudes of VOC are reasonably consistent with the predictions of a calculation combining a bandtail+defect picture for recombination and a hydrogen-collision model for defect generation. The version of the hydrogen-collision model that we used assumes that only bandtail recombination drives the hydrogen collision processes. Within this picture, the crossover between bandtail and defect recombination occurs on the same timescale as the ?light-induced annealing? process that accounts for stabilization of the optoelectronic properties for long light-soaking times.
Venue	MRS 2005 Spring Meeting, San Francisco, CA, Symposium A
Sources	Syracuse University; Uni-Solar Ovonic
Document Type	Conference Papers (Word document)
Resource Date	04/2005

Post Date	02/07/2005
Title	THE ROLE OF POLYCRYSTALLIN THIN-FILM PV TECHNOLOGIES FOR ACHIEVING MID-TERM MARKET-COMPETITIVE PV MODULES
Link	(MS Word 123 KB)
Authors	B. Von Roedern, K. Zweibel
Description	Using efficiency as the main parameter, projecting the cost competitiveness of thin films and x-Si. Current commercial status of CuInSe₂ alloys (collectively, CIS) and CdTe-based photovoltaic (PV) modules, comparing the performance of commercial products with the results achieved for solar cell and prototype module champions. We provide an update for these PV cell and module technologies, and also compare CIS and CdTe performance levels to the results achieved by the crystalline Si PV industry. This comparison shows that CIS and CdTe module technology presently offers the best (and perhaps only) approach for significantly exceeding the cost/performance levels established by crystalline Si PV technologies. A semi-empirical methodology is used for comparing "champion" solar cell and prototype module data with performance achieved on manufacturing lines. Using a conservative assumption that thin-film technologies will eliminate the 40% of PV module costs arising from the Si wafer or ribbon, we estimate the future performance of all established PV module candidates, and conclude that, based on 2004 knowledge about each PV technology, CIS and CdTe should provide cost-competitive advantages over crystalline Si.
Venue	IEEE PV Specialists Conference, 2004
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Word document)
Resource Date	01/2005

Post Date	02/11/2005
Title	LIFE CYCLE ASSESSMENT OF PHOTOVOLTAICS: PERCEPTIONS, NEEDS, AND CHALLENGES
Link	(PDF 222 KB) Download Acrobat Reader.
Authors	E. A. Alsema, M. J. De Wild-Scholten, V. Fthenakis
Description	High impact publications recently depicted PV technologies as having higher external environmental costs than those of nuclear energy and natural-gas-fueled power plants. These assessments are based on old data and unbalanced assumptions, and they illustrate the need for LCA data describing the continuously improving photovoltaic systems and the inclusion of social benefits in this comparison.
Venue	IEEE Photovoltaic Specialistis Conference, Jan. 3-7, 2005, Orlando, FL
Sources	Brookhaven National Laboratory; Energy Research Centre of the Netherlands; Utrecht University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/15/2005
Title	ANALYTICAL RESULTS OF OUTPUT RESTRICTION DUE TO THE VOLTAGE INCREASING OF POWER DISTRIBUTION LINE IN GRID-CONNECTED CLUSTERED PV SYSTEMS
Link	(PDF 2.4 MB) Download Acrobat Reader.
Authors	et al., Y. Ueda
Description	Output restriction to prevent over voltage of power distribution line is one of the concerns for grid-connected clustered PV systems. To investigate the behavior of clustered PV systems, "Demonstrative research on clustered PV systems" has being conducted from December, 2002 in Gunma, Japan. More than 200 residential PV systems are already installed in demonstrative research area. Operation point of array output is estimated using minutely averages of collected data. The method to quantify loss due to output restriction is developed in this study.
Venue	IEEE PVSC
Source	Tokyo University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/15/2005
Title	EARLY PERFORMANCE FOR THE ROOF-MOUNTED, 20-KW THIN FILM CDTE PV-ARRAY AT JASPER RIDGE
Link	(PDF 364 KB) Download Acrobat Reader.
Authors	et al., J. H. Scofield
Description	Here we report early performance for the grid-connected, 20-kW CdTe PV array installed on the roof of the Leslie Shao-ming Sun Field Station at the Jasper Ridge Biological Preserve. The array was installed in May 2002. Data are reported for 20-mos beginning April 2003. The array originally consisted of 275, BP Solar 80W thin-film CdTe modules arranged in 11-module strings. The monitoring system logged data from 9 sensors on 1-min intervals. Monitoring showed problems with maximum power tracking associated with module degradation, ele-vated module temperatures, and the finite voltage window of the 208VAC-3p inverter. The problems were addressed in May 2004 by re-wiring the array and reprogramming the inverter, resulting in a 20% increase in energy production.
Venue	IEEE PVSC
Source	Oberlin College
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	01/2005

Post Date	02/04/2005
Title	STUDY OF POTENTIAL COST REDUCTIONS RESULTING FROM SUPER-LARGE-SCALE MANUFACTURING OF PV MODULES
Link	(MS Word 112 KB)
Authors	R. Arya, M. Keshner
Description	Short version of multi-GW production report
Venue	NREL Solar Review
Source	Hewlett Packard
Document Type	Conference Papers (Word document)
Resource Date	10/2004

Post Date	02/09/2005
Title	PHYSICAL MODES OF THIN-FILM PV DEGRADATION
Link	(PDF 267 KB) Download Acrobat Reader.
Authors	et al., V. G. Karpov
Description	We discuss physical modes of degradation related to the small thickness and lack of crystallinity in thin-film PV. We discriminate between 1) uniform material degradation through defect generation, light-induced diffusion, and electro-migration; 2) nonuniform degradation through ohmic or non-ohmic shunts; 3) metal contact deterioration. The first can equally apply to bulk and thin-film PV. Two others are specific to thin-film PV.
Venue	IEEE
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2004

Post Date	05/10/2005
Title	NEW R&D TRENDS IN EUROPE ON THIN-SILICON PHOTOVOLTAICS
Link	(PDF 159 KB) Download Acrobat Reader.
Authors	et al., F. Roca
Description	About 99% of the solar-cell world production for PV terrestrial applications is dominated by silicon, of whose share, about 80% corresponds to wafer technology. Experience has induced the conviction that silicon technology must keep this predominant position for the next 10 years. Progress in wafer technology is needed in the direction of increasing production and lowering costs of feedstock, mainly by investigating new growth processes leading to a cheaper silicon of an acceptable quality. The development of medium-thickness polycrystalline ribbon silicon and similar silicon-based materials is in the forefront of photovoltaic R&D. In parallel, the efforts on thin-film silicon technology must be concentrated on enhancing material quality by improving film crystallinity and simultaneously thickness and growth rate. New approaches for the preparation of silicon impose a convergence of two research lines traditionally separated. The European state of the art in thin silicon for PV is analysed and described. A successful European RTD strategy imposes the collaboration of public and private institutions both within the present Framework Programme, FP5, and even more in the coming FP6, by means of Networks of Excellence (NoE) and Integrated projects (IP) in order to create the so called European Research Area.
Venue
Source	ENEA
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/07/2005
Title	TECHNOLOGY AND MARKET CHALLENGES TO MAINSTREAM THIN-FILM PHOTOVOLTAIC MODULES AND APPLICATIONS
Link	(PDF 276 KB) Download Acrobat Reader.
Author	R. Arya
Description	Technology and manufacturing advances over the past 25 years has led to widespread commercial use of thin film modules in many consumer applications. The three leading thin film solar module technologies are - amorphous silicon alloys (a-Si), copper indium diselenide alloys (CIGS), and cadmium telluride CdTe). These three technologies have demonstrated solar cells with efficiencies ~13% (a-Si), ~19% (CIGS), and ~16.5% (CdTe) respectively. Large area power modules are in various stages of initial production with these technologies and the module performance is in the 6%-11% range. Several manufacturing plants are in operation with plant capacities ranging from 3 MW to 30 MW. These plants are continuously increasing production with the present annual production of 1 MW to 5 MW. Technical challenges lie ahead in improving the module performance by reducing the gap between R&D cells and manufactured products so that they can successfully compete with crystalline silicon modules. Reliability of thin film modules in systems has been demonstrated with all three technologies with a fair degree of success. Several 1-480 kW grid-connected thin film module arrays are in deployment worldwide. Thin film modules are finding increasing acceptance for BIPV applications like roofs, facades, awnings etc. used in residential and commercial buildings. The cost of modules and market acceptance with new technologies still remains a major challenge to successful penetration of mainstream photovoltaic markets.
Venue
Source	N/A
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2004

Post Date	02/08/2005
Title	SI:H MATERIALS AND SOLAR CELLS RESEARCH AT PENN STATE
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Authors	et al., C. Wronski
Description	Progress in Research on Si:H Materials and Solar Cells Research at Penn State.
Venue	DOE Photovoltaics Subprogram Peer Review August 13-15, 2003
Source	Pennsylvania State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	08/13/2003

Post Date	03/15/2005
Title	OVERVIEW OF AMORPHOUS SILICON (A-SI) PHOTOVOLTAIC INSTALLATIONS AT SMUD
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Author	D. E. Osborn
Description	The Sacramento Municipal Utility District (SMUD) Solar Program has installed over 10 MW of photovoltaic (PV) systems including more than 2,000 kW of amorphous silicon (a-Si), thin film PV systems installed since 1994 in systems ranging from 1 kW to 700 kW. While lower in efficiency compared to the more traditional single-crystal silicon (c-Si) and polycrystalline silicon (pc-Si) PV modules, the significantly lower price per Watt of a-Si can often result in dramatic turnkey system savings despite increased area-related installation costs. arrays at PV power stations.
Venue	ASES Solar 2003 * June 2003 * Austin, TX
Source	Spectrum Energy Corp
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	06/2003

Post Date	02/09/2005
Title	THE MESOSCALE PHYSICS OF LARGE-AREA PHOTOVOLTAICS
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Authors	et al., V. G. Karpov
Description	Recent findings make the physics of large-area thin-film devices a distinctive field of its own, considerably different from that of microelectronics. We show that (i) large-area thin-film photovoltaic (PV) devices are intrinsically nonuniform in the lateral directions, (ii) the nonuniformity spans over microscopically large dimensions, which can vary dramatically (from microns to meters) depending on light intensity and bias, and (iii) the nonuniformity significantly impacts the device performance and stability. Our understanding suggests the concept of interfacial layer that blocks the nonuniformity effects and can be applied photo-electrochemically. This concept is experimentally verified.
Venue	29th IEEE Osaka
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/16/2003

Post Date	03/15/2005
Title	LARGE-AREA DEPOSITION FOR CRYSTALLINE SILICON ON GLASS MODULES
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Author	P. A. Basore
Description	This paper presents the current status of the Crystalline Silicon on Glass (CSG) technology for lowcost photovoltaic modules that is being developed at Pacific Solar. This technology combines the low manufacturing cost of large-area monolithic construction with the established durability of crystalline silicon. The heart of the manufacturing sequence for this technology is the PECVD silicon deposition process. Equipment developed for the flat-panel display industry appears to meet the requirements for this process. A single-chamber KAI-800 system from Unaxis has been installed at Pacific Solar that deposits silicon layers onto 0.7-m2 ...
Venue	IEEE
Source	Pacific Solar Pty Ltd
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	05/16/2003

Post Date	03/15/2005
Title	PROPERTIES OF SI:H MIXED AMORPHOUS MICROCRYSTALLINE PHASES
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Authors	R. W. Collins, C. Wronski
Description	at The Pennsylvania State University have shown that the thin film Si:H prepared under moderate-to-high H2-dilution conditions with low temperature rf plasma enhanced chemical vapor deposition (PECVD) evolves from the amorphous phase to a mixed amorphous + microcrystalline phase [(a+�c)-Si:H] with the accumulated thickness of the layer. The thin film material in the amorphous regime of growth has been called "protocrystalline" Si:H and exhibits a higher degree of ordering than materials deposited under similar conditions without H2-dilution [1-3]. Furthermore they showed that the phase evolution of this material with thickness and, in particular, the transition to the mixed-phase (a+�c)-Si:H material, depends not only on hydrogen dilution ratios, R=[H2]/[SiH4], but also on the substrate material. Consequently, without using real time spectroscopic ellipsometry (RTSE) or equally powerful techniques, it is not possible to control the growth of the protocrystalline Si:H materials and cell structures or to characterize their properties reliably. The insights into the growth process and microstructural evolution into the (a+�
Venue	NREL National Team meeting
Source	Pennsylvania State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/02/2005
Title	COMPARISON OF ENERGY PRODUCTION AND PERFORMANCE FROM FLAT-PLATE PHOTOVOLTAIC MODULE TECHNOLOGIES DEPLOYED AT FIXED TILT
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Author	J. A. del Cueto
Description	energy rating by technology
Venue
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	03/25/2005
Title	OPTIMIZATION OF PHASE-ENGINEERED A-SI:H-BASED MULTIJUNCTION SOLAR CELLS
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Authors	et al., C. Wronski
Description	A comprehensive understanding is being developed on the subjects of Si:H material deposition as well as device limiting mechanisms. First, it has been demonstrated that the protocrystalline nature of the p-layers and not their microcrystalline nature is responsible for obtaining high VOC and also that VOC can be maximized through the deposition procedure. Second, recombination at p/i interfaces has been identified and quantified on cells with different i-layers and a-Si:H p-i interface layers. The bulk recombination in both the JD-V and JSC-VOC characteristics,which exhibit superposition, is found to be consistent with the Shockley-Reed-Hall model, and the observed spatially uniform distributions of defects in the i-layers are contrary to the predictions of the defect pool model. Third, results obtained on sub-bandgap absorption spectra
Venue	NCPV and Solar Program Review Meeting 2003 NREL/CD-520-33586 Page 789
Source	Pennsylvania State University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/07/2005
Title	PRACTICAL DOPING PRINCIPLES
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Author	A. Zunger
Description	Doping compound semiconductors.
Venue	NREL DOE Solar Program Review Meeting 2003
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/08/2005
Title	STATUS OF AMORPHOUS AND CRYSTALLINE THIN-FILM SILICON SOLAR CELL ACTIVITIES
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Author	B. Von Roedern
Description	This paper reviews the recent activities and accomplishments of the national Amorphous Silicon Team and a (crystalline) thin-film-Si subteam that was implemented in 2002 to research solar cell devices based on thin-crystalline-Si-based layers. This paper reports the evolution of team organization, technical highlights from recent team meetings, and an outlook on commercialization potential.
Venue	NCPV and Solar Program Review Meeting 2003
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/07/2005
Title	PROGRESS IN U.S. PHOTOVOLTAICS: LOOKING BACK 30 YEARS AND LOOKING AHEAD 20
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Author	T. Surek
Description	Technology and learning curve analysis of R&D.
Venue	Osaka IEEE
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	03/15/2005
Title	STATUS OF HYDROGENATED MICROCRYSTALLINE SILICON SOLAR CELLS AT UNITED SOLAR
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Authors	et al., J. Yang
Description	We have studied the performance of hydrogenated microcrystalline silicon (�c-Si:H) solar cells using three different deposition techniques. Deposition rates ranging from low (~1�/s), to medium (~3-10 �/s), to high (~20 - 30 �/s) have been obtained by using conventional radio frequency (RF), modified very high frequency (MVHF), and microwave (�-wave) excitations, respectively; initial activearea efficiencies of 7.4%, 7.1%, and 4.9% have been achieved for the respective techniques in a single-junction structure. Double-junction cells using a-Si:H in the top and �c-Si:H in the bottom have yielded initial active-area efficiencies of 13% and 12.3% for RF and MVHF techniques, respectively. Stability and other issues will be reported.
Venue	NCPV and Solar Program Review Meeting 2003 NREL/CD-520-33586 Page 556
Source	Uni-Solar Ovonic
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2003

Post Date	02/09/2005
Title	MICRONONUNIFORMITY EFFECTS IN THIN-FILM PHOTOVOLTAICS
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Authors	A. Compaan, V. G. Karpov, D. Shvydka
Description	We discuss effects of micrononuniformities on thin-film photovoltaics. The key factors are the device large area and the presence of potential barriers. We model the nonuniformity effects in the terms of random microdiodes connected in parallel through a resistive electrode. The microdiodes of low open circuit voltages affect macroscopically large regions. They strongly reduce the device performance and induce its nonuniform degradation in several different modes. We support our predictions by experiments.
Venue	2002 IEEE PVSC
Source	University of Toledo
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2002

Post Date	02/08/2005
Title	MODEL FOR STAEBLER-WRONSKI DEGRADATION DEDUCED FROM LONG-TERM, CONTROLLED LIGHT-SOAKING EXPERIMENTS
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Authors	J. A. del Cueto, B. Von Roedern
Description	Long-term light-soaking experiments of amorphous silicon photovoltaic modules have now established that stabilization of the degradation occurs at levels that depend significantly on the operating conditions, as well as on the operating history of the modules. We suggest that stabilization occurs because of the introduction of degradation mechanisms with different time constants and annealing activation energies, depending on the exposure conditions. Stabilization will occur once a sufficient accumulation of different degradation mechanisms occurs. We find that operating module temperature during light-soaking is the most important parameter for determining stabilized performance. Next in importance is the exposure history of the device. The precise value of the light intensity seems least important in determining the stabilized efficiency, as long as its level is a significant fraction of 1-sun.
Venue	MRS 2000
Source	National Renewable Energy Laboratory
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2002

Post Date	03/15/2005
Title	SUPERIOR ENERGY YIELDS OF UNI-SOLAR� TRIPLE JUNCTION THIN FILM SILICON SOLAR CELLS COMPARED TO CRYSTALLINE SILICON SOLAR CELLS UNDER REAL OUTDOOR CONDITIONS IN WESTERN EUROPE
Link	(MS Word 747 KB)
Authors	et al., M. van Cleef
Description	For many years, amorphous silicon photovoltaic modules have had difficulties to establish themselves in the grid-connected PV-market. Causes for this lack of market acceptance of first generation amorphous silicon PV modules were their relatively low conversion efficiencies, unstable power and not well understood outdoor characteristics. Various manufacturers of amorphous silicon modules have resolved these initial problems by enhancing the efficiencies of their cells, while at the same time improving the long-term stability of the products. Still, the outdoor behaviour of amorphous silicon modules is not well understood by many users, even by insiders of the PV-community. Results of this study will show that new generation multi-junction amorphous silicon modules, and in particular UNI-SOLAR� modules based on the Triple Junction solar cells, perform excellent under western European climatic conditions, with yields and performance ratios significantly higher than all present crystalline silicon technologies. This effect is especially pronounced under low light conditions and under non-ideal orientations. The enhanced outdoor performance, up to 20 % higher on a yearly kWh/kWp base, can be attributed to the higher sensitivity for low light conditions and for diffuse light, better performance at high temperatures and improved shadow tolerance of UNI-SOLAR� modules.
Venue	17th EuroPV Solar Energy Conference, Munich
Source	Energy Conversion Devices
Document Type	Conference Papers (Word document)
Resource Date	10/2001

Post Date	02/07/2005
Title	PV SOLAR ELECTRICITY: ONE AMONG THE NEW MILLENNIUM INDUSTRIES
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Author	W. Hoffmann
Description	ABSTRACT: During recent years, solar electricity generation based on photovoltaics has developed into an industry at annual growth rates above 20%. Major market segments served by this industry comprise consumer applications, remote industrial systems, developing countries, and grid-connected systems. The potential in these markets supports sustained future growth, particularly for applications in developing countries and gridconnected systems in the industrial countries, where PV-generated electricity eventually will start to compete with peak grid power. Backed by price experience curves and a laboratory proven technology road map, a module turnover representing 100 billion worlwide can be extrapolated. A sustainable energy contribution to the worldwide energy mix in subsequent decades is foreseen as a result of competitive PV solar electricity applications. Keywords: PV Market Growth ? 1: Strategy ? 2: Cost Reduction ? 3
Venue	17th European Photovoltaic Solar Energy Conference, Munich, Germany, 22-26 October 2001
Source	RWE Schott
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	10/2001

Post Date	03/22/2005
Title	GUIDING PRINCIPLE TO DEVELOP INTRINSIC MICROCRYSTALLINE SILICON ABSORBER LAYER FOR SOLAR CELL BY HOT-WIRE CVD
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Authors	et al., A. R. Middya
Description	We report on ways to develop device quality microcrystalline silicon (?c-Si:H) intrinsic layer with high growth rate by hot-wire chemical vapor deposition (HWCVD). With combine approach of controlling impurities and moderate H-dilution [H2/SiH4 ? 2.5], we developed, for the first time, highly photosensitive (103) ?c-Si:H films with high growth rate (>1 nm/s); the microstructure of the film is found to be close to amorphous phase (fc ? 46 � 5%). The photosensitivity systematically decreases with fc and saturates to 10 for fc > 70%. On application of these materials in non-optimized pin ?c-Si:H solar cell structure yields 700 mV open-circuit voltage however, surprisingly low fill factor and short circuit current. The importance of reduction of oxygen impurities [O], adequate passivation of grain boundary (GB) as well as presence of inactive GB of (220) orientation to achieve efficient uc-Si:H solar cells are discussed.
Venue	Mat. Res. Soc. Symp. Proc. Vol. 664
Source	University of Kaiserslautern
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2001

Post Date	03/15/2005
Title	STABILITY AND NANOSTRUCURE OF HETEROGENEOUS AMORPHOUS SILICON THIN-FILM SYNTHESIZED UNDER HIGH CHAMBER PRESSURE (500 TO 2200 MTORR) REGIME OF RF PECVD
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Author	A. R. Middya
Description	We report on improvement in stability of a new type of amorphous silicon films, synthesized (growth rate > 0.1 nm/s) by driving the plasma condition close to the (or "?-regime") of rf PECVD. These films exhibit high mobility-lifetime products [(??)annld ? 10- 4 cm2/V, ?ph/?d ? 5-10x105, Ea ? 0.7 - 0.9 eV ], compact network structure [CH ? 7 to 8 at%, nanovoid density < 0.01 %, ? ? 2.23 � 0.01 gm/cm3], new features of optical properties and density-of-state (DOS) above EF is significantly lower than that of state-of-the art films. The kinetics of light-induced (AM 1.5) degradation of ?? is very fast and saturated ?? ? 10-6 cm2/V, a value similar to that of conventional a-Si:H films at annealed state. The improved stability of "new" a-Si films, henceforth it will be denoted as "quasi-amorphous silicon (qm-Si) thinfilm", will be correlated with its specific nanostructure.
Venue	Mat. Res. Soc. Symp. Proc. Vol. 664
Source	Syracuse University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2001

Post Date	02/11/2005
Title	HEALTH, SAFETY AND ENVIRONMENTAL ISSUES IN THIN FILM MANUFACTURING
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Authors	E. A. Alsema, et al.
Description	An investigation is made of Health, Safety and Environmental (HSE) aspects for the manufacturing, use and decommissioning of CdTe, CIS and a-Si modules. Issues regarding energy requirements, resource availability, emissions of toxic materials, occupational health and safety and module waste treatment are reviewed. Waste streams in thin film module manufacturing are analyzed in detail and treatment methods are discussed. Finally the technological options for thin film module recycling are investigated. It is concluded that there are no serious HSE bottlenecks for upscaling to production levels of 500 MWp/yr and that adequate methods are available for treatment of the manufacturing wastes. However, on the longer term issues regarding CdTe and CIS module waste treatment, In and Te resource availibility and module recycling need to adressed. Appropriate recycling methods for CdTe and CIS modules do not exist at present but the problem is being adressed by the PV industry.
Venue
Source	Utrecht University
Document Type	Conference Papers (Adobe Postscript file)
Resource Date	2000

Presentations

Post Date	04/30/2007
Title	SI THIN-FILM PHOTOVOLTAICS PROGRAM IN THE U.S.
Link	(PDF 1.5 MB) Download Acrobat Reader.
Author	B. Von Roedern
Description	Presentation Outline: (1) History of U.S. a-Si (film-Si) program (2) Results of activities (3) Competing PV Technologies (4) Outlook
Venue	presented at International Workshop upon Thin Film Silicon Solar Cells, Nara, Japan, 2/28 - 3/2/2007
Source	National Renewable Energy Laboratory
Document Type	Presentation (Adobe Postscript file)
Resource Date	02/2007

Post Date	06/05/2006
Title	PHASE DIAGRAM FOR SI(1-X)GE(X):H THIN FILMS
Link	(PowerPoint 19.1 MB)
Authors	R. W. Collins, N. Podraza, C. Wronski
Description	Hydrogen Dilution Phase Diagrams for a-SiGe:H, comparision to HE-dilution
Venue	N. Podzara and R. Collins, University of Toledo, presentation at the a-Si team meeting, 4/17/2006
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/07/2006
Title	CHEMICAL ANNEALING FOR IMPROVED STABILITY
Link	(PowerPoint 245 KB)
Author	V. L. Dalal
Description	Discussion of the benefits of low-energy (<50 eV) ion bombardment on film properties
Venue	V. Dalal, Iowa State University, presentation, a-Si Team Meeting, 04/17/2006
Source	Iowa State University
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/06/2006
Title	CORPORATE OVERVIEW
Link	(PowerPoint 3.4 MB)
Author	J. Yang
Description	Uni-Solar's Commercial Expansion and Company Overview
Venue	J. Yang, United Solar, presentation, a-Si Team Meeting 04/17/2006
Source	Uni-Solar Ovonic
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/05/2006
Title	INNOVATIVE CHARACTERIZATION OF AMORPHOUS AND THIN-FILM SILICON FOR IMPROVED MODULE PERFORMANCE
Link	(PowerPoint 3.2 MB)
Author	J. D. Cohen
Description	Defect spectra for NREL HW a-SiGe:H, influence of oxygen, defect spectra for nc-Si:H
Venue	D. Cohen, University of Oregon, presentation, a-Si Team Meeting 4/17/2006
Source	University of Oregon
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/05/2006
Title	RECRYSTALLIZED LARGE-GRAIN SI FILMS
Link	(PowerPoint 16.2 MB)
Authors	M. Lu, O. Ebil, U. Das, S. S. Hegedus, R. W. Birkmire
Description	Analyses of Si films prepared by Al-induced recrystallization (exchange layer recrystallization)
Venue
Source	University of Delaware
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/05/2006
Title	OPTICAL CHARACTERIZATION OF ZNO/AG STRUCTURES FOR APPLICATIONS AS BACK-REFLECTORS IN THIN FILM SI SOLAR CELLS
Link	(PowerPoint 3.2 MB)
Authors	R. W. Collins, N. Podraza, X. Deng
Description	Spectroscopic Ellipsometry was used to study various back-reflector formulations
Venue	R. Collins, University of Toledo, presentation, a-Si Team Meeting 04/17/2006
Source	University of Toledo
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/05/2006
Title	PIER RENEWABLES SOLAR RD&D POLICY DRIVERS, CURRENT ACTIVITIES, AND FUTURE PLANS
Link	(PowerPoint 11.7 MB)
Authors	G. Kibrya, H. Mohammed
Description
Venue	G. Kibrya and H. Mohammed, PIER (CA Public Interest Energy Research Program), presentation, a-Si Team Meeting, 04/17/2006
Source	PIER CA Energy Commission (Public Interest Energy Research Program)
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/06/2006
Title	IMPROVEMENT OF MULTI-JUNCTION SOLAR CELLS WITH NC-SI:H MIDDLE AND BOTTOM CELL
Link	(PowerPoint 2.1 MB)
Authors	B. Yan, G. Yue, G. Ganguly, J. Yang, S. Guha
Description	? 8.99% initial and 8.50% stable active-area efficiency for a nc-Si:H single-junction cell made with MVHF at 5-8 �/s ? 15.1% initial active-area efficiency for an a-Si:H/a-SiGe:H/nc-Si:H triple-junction structure, where the top and the middle cells were made with RF at a low rate, the bottom cell with MVHF at a high rate ? 14.1% initial and 13.2% stable active-area efficiency for an a-Si:H/nc-Si:H/nc-Si:H triple-junction structure, where the top were made with RF at a low rate, the middle and bottom cell with MVHF at a high rate ? 9.5% stable aperture-area (420 cm2) efficiency for an encapsulated a-Si:H/nc-Si:H double-junction structure.
Venue	B. Yan, United Solar, presentation, a-Si Team Meeting, 04/17/2006
Source	Uni-Solar Ovonic
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/06/2006
Title	CONDUCTIVE AFM MEASUREMENTS ON HYDROGENATED AMORPHOUS/NANOCRYSTALLINE MIXED-PHASE SOLAR CELLS
Link	(PowerPoint 5.9 MB)
Authors	B. Yan, S. Guha, C. Teplin, H. Moutinho, M. M. Al-Jassim
Description	1. We have used C-AFM to measure the local current mapping in the solar cells showing amorphous, mixed-phase, and nanocrystalline characteristics. 2. High current spikes were observed in the nanocrystalline areas. 3. The density of the current-spikes increases with the increase of crystalline phase. 4. A fully a-Si:H thick i/p buffer layer significantly reduced the magnitude of the current spikes. 5. Comparing the C-AFM images with the surface morphology, we believe that the areas with high current spikes are aggregations of small nanocrystallites. 6. These clusters of nanocrystallites with size of ~500 nm can form microscopic diodes. 7. These results provide additional evidence for the parallel-connected two-diode model for the mixed-phase solar cell and explain the observed dramatic drop of Voc at very low nanocrystalline volume fraction.
Venue	B. Yan, Uni-Solar, presentation, a-Si Team Meeting 04/17/2006
Sources	National Renewable Energy Laboratory; Uni-Solar Ovonic
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

Post Date	06/06/2006
Title	SPATIALLY RESOLVED RAMAN SPECTROSCOPY FOR A-SI:H & NC-SI STUDIES
Link	(PowerPoint 580 KB)
Author	C. W. Teplin
Description	Micro-Raman Studies using different wavelength (penetration depths)
Venue	C. Teplin, NREL, presentation, a-Si Team Meeting 04/17/2006
Source	National Renewable Energy Laboratory
Document Type	Presentation (Powerpoint presentation)
Resource Date	04/17/2006

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Post Date	06/07/2006
Title	ELECTRONIC PROPERTIES IN NC-SI:H