Microstructure of Amorphous-Silicon-Based Solar Cell Materials by Small-Angle X-Ray Scattering; Final Subcontract Report: 6 April 1994 - 30 June 1998

Microstructure of Amorphous-Silicon-Based Solar Cell Materials by Small-Angle X-Ray Scattering; Final Subcontract Report: 6 April 1994 - 30 June 1998

Date: December 8, 1998
Creator: Williamson, D.L. (Department of Physics: Colorado School of Mines)
Description: This report describes work performed to provide details of the microstructure in high-quality hydrogenated amorphous silicon and related alloys for the nanometer size scale. The materials studied were prepared by current state-of-the-art deposition methods, as well as new and emerging deposition techniques. The purpose was to establish the role of microstructural features in controlling the opto-electronic and photovoltaic properties. The approach centered around the use of the uncommon technique of small-angle X-ray scattering (SAXS), which is highly sensitive to microvoids and columnar-like microstructure. Nanovoids of H-rich clusters with 1 to 4 nm sizes in a-Si:H at the 1 vol.% level correlate with poor solar-cell and opto-electronic behavior. Larger-scale features due either to surface roughness or residual columnar-like structures were found in present state-of-the-art device material. Ge alloying above about 10 to 20 at.% typically leads to significant increases in heterogeneity , and this has been shown to be due in part to non-uniform Ge distributions. Ge additions also cause columnar-like growth, but this can be reduced or eliminated by enhanced ion bombardment during growth. In contrast, C alloying typically induces a random nanostructure consisting of a narrow size distribution of 1-nm-sized objects with a high density, consistent with the notably ...
Contributing Partner: UNT Libraries Government Documents Department
Identifying Electronic Properties Relevant to Improving Stability in a-Si:H-Based Cells and Overall Performance in a-Si,Ge:H-Based Cells; final Subcontract Report, 18 April 1994-15 January 1998

Identifying Electronic Properties Relevant to Improving Stability in a-Si:H-Based Cells and Overall Performance in a-Si,Ge:H-Based Cells; final Subcontract Report, 18 April 1994-15 January 1998

Date: November 16, 1998
Creator: Cohen, J. D. (Department of Physics and Materials Science Institute, University of Oregon)
Description: The work carried out by the University of Oregon Under this subcontract focused on the characterization and evaluation of low-gap (a-Si,Ge:H) alloy materials and on issues related to overall stability in the mid-gap (a-SiH) materials. First, researchers characterized an extensive series of Uni-Solar a-Si,Ge:H samples using drive-level capacitance profiling and the analysis of sub-band-gap photocapacitance and photocurrent spectra. Thus, several bands of deep defect transitions were identified. Researchers were able to verify that charged defects are responsible for the different observed defect bands in device-quality a-Si,Ge:H alloy material. Second, they reported results of their measurements on a-Si,Ge:H alloy ''cathodic'' samples produced at Harvard University; these samples were found to exhibit significantly lower defect densities in the high Ge composition range (>50at.% Ge) than alloy samples produced either by conventional glow discharge of photo-chemical vapor deposition. Third, they performed voltage pulse stimulated capacitance transient measurements on a-Si:H/a-Si,Ge:H heterostructure samples to look for carrier trapping states that might be associated with this interface; they found there was a clear signature of trapped hole emission extending over long times associated specifically with the interface itself in concentrations of roughly 10{sup 11} cm{sup -2}. Fourth, researchers reported the results on several hot-wire a-Si:H samples ...
Contributing Partner: UNT Libraries Government Documents Department
Device Physics of Thin-Film Polycrystalline Cells and Modules; Final Subcontract Report; 6 December 1993-15 March 1998

Device Physics of Thin-Film Polycrystalline Cells and Modules; Final Subcontract Report; 6 December 1993-15 March 1998

Date: May 3, 1999
Creator: Sites, J. R. (Department of Physics, Colorado State University, Ft. Collins, Colorado)
Description: This report describes work performed under this subcontract by Colorado State University (CSU). The results of the subcontract effort included progress in understanding CdTe and Cu(In1-xGax)Se2-based solar cells, in developing additional measurement and analysis techniques at the module level, and in strengthening collaboration within the thin-film polycrystalline solar-cell community. A major part of the CdTe work consisted of elevated-temperature stress tests to determine fabrication and operation conditions that minimize the possibility of long-term performance changes. Other CdTe studies included analysis of the back-contact junction, complete photon accounting, and the tradeoff with thin CdS between photocurrent gain and voltage loss. The Cu(In1-xGax)Se2 studies included work on the role of sodium in enhancing performance, the conditions under which conduction-band offsets affect cell performance, the transient effects of cycling between light and dark conditions, and detailed analysis of several individual series of cells. One aspect of thin-film module analysis has been addressing the differences in approach needed for relatively large individual cells made without grids. Most work, however, focused on analysis of laser-scanning data, including defect signatures, photocurrent/shunting separation, and the effects of forward bias or high-intensity light. Collaborations with other laboratories continued on an individual basis, and starting in 1994, collaboration was ...
Contributing Partner: UNT Libraries Government Documents Department
Final Report DOE Grant DE-FG02-03ER41230-A000

Final Report DOE Grant DE-FG02-03ER41230-A000

Date: June 9, 2004
Creator: E.W. Beier Department of Physics and Astronomy University of Pennsylvania Philadelphia, PA 19104-6396
Description: Final report on conference grant supporting the American Physical Society Division of Particles and Fields meeting in Philadlephia, PA April 5-8, 2003.
Contributing Partner: UNT Libraries Government Documents Department
Research on High-Bandgap Materials and Amorphous Silicon-Based Solar Cells, Final Technical Report, 15 May 1994-15 January 1998

Research on High-Bandgap Materials and Amorphous Silicon-Based Solar Cells, Final Technical Report, 15 May 1994-15 January 1998

Date: December 28, 1998
Creator: Schiff, E. A.; Gu, Q.; Jiang, L.; Lyou, J.; Nurdjaja, I. & Rao, P. (Department of Physics, Syracuse University)
Description: This report describes work performed by Syracuse University under this subcontract. Researchers developed a technique based on electroabsorption measurements for obtaining quantitative estimates of the built-in potential Vbi in a-Si:H-based heterostructure solar cells incorporating microcrystalline or a-SiC:H p layers. Using this new electroabsorption technique, researchers confirmed previous estimates of Vbi {yields} 1.0 V in a-Si:H solar cells with ''conventional'' intrinsic layers and either microcrystalline or a-SiC:H p layers. Researchers also explored the recent claim that light-soaking of a-Si:H substantially changes the polarized electroabsorption associated with interband optical transitions (and hence, not defect transitions). Researchers confirmed measurements of improved (5') hole drift mobilities in some specially prepared a-Si:H samples. Disturbingly, solar cells made with such materials did not show improved efficiencies. Researchers significantly clarified the relationship of ambipolar diffusion-length measurements to hole drift mobilities in a-Si:H, and have shown that the photocapacitance measurements can be interpreted in terms of hole drift mobilities in amorphous silicon. They also completed a survey of thin BP:H and BPC:H films prepared by plasma deposition using phosphine, diborane, trimethylboron, and hydrogen as precursor gases.
Contributing Partner: UNT Libraries Government Documents Department
Analysis of Cu Diffusion in ZnTe-Based Contacts for Thin-Film CdS/CdTe Solar Cells

Analysis of Cu Diffusion in ZnTe-Based Contacts for Thin-Film CdS/CdTe Solar Cells

Date: October 27, 1998
Creator: Narayanswamy, C. (Department of Physics & Astronomy, University of Toledo) & Gessert, T. A. and Asher, S. E. (National Renewable Energy Laboratory)
Description: Ohmic contacts to thin-film CdS/CdTe photovoltaic devices have been formed using a two-layer contact interface of undoped ZnTe (ZnTe) and Cu-doped ZnTe (ZnTe:Cu), followed by Ni or Ti as an outer metallization. Secondary ion mass spectroscopy (SIMS) is used to study Cu diffusion within this back-contact structure, and also, to monitor Cu diffusion from the contact into the CdTe. When Ni metallization is used, the ZnTe:Cu layer becomes increasingly depleted of Cu, and Ni diffusion into the ZnTe:Cu increases as the contact deposition temperature increases from 100 C to 300 C. Cu depletion is not observed when Ni is replaced with Ti. Diffusion of Cu from the ZnTe:Cu layer into the ZnTe layer also increases with contact deposition temperature, and produces a buildup of Cu at the ZnTe/CdTe interface. High-mass resolution SIMS indicates that, although Cu levels in the CdTe remain low, Cu diffusion from the contact proceeds into the CdTe layer and toward the CdTe/CdS junction region.
Contributing Partner: UNT Libraries Government Documents Department
15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films

15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films

Date: May 25, 1999
Creator: Bhattacharya, R. N.; Batchelor, W.; Contreras, M. A.; Noufi, R. N. (National Renewable Energy Laboratory); Hiltner, J. F. & Sites, J. R. (Department of Physics, Colorado State University)
Description: We have fabricated 15.4%- and 12.4%-efficient CuIn1-XGaXSe2 (CIGS)-based photovoltaic devices from solution-based electrodeposition (ED) and electroless-deposition (EL) precursors. As-deposited precursors are Cu-rich CIGS. Additional In, Ga, and Se are added to the ED and EL precursor films by physical vapor deposition (PVD) to adjust the final film composition to CuIn1-XGaXSe2. The ED and EL device parameters are compared with those of a recent world record, an 18.8%-efficient PVD device. The tools used for comparison are current voltage, capacitance voltage, and spectral response characteristics.
Contributing 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

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

Date: November 19, 1998
Creator: Tang, Y. (Princeton Electronic Systems, Inc.); Dong, S.; Sun, G. S.; Braunstein, R. (Department of Physics, University of California) & von Roedern, B. (National Renewable Energy Laboratory)
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.
Contributing Partner: UNT Libraries Government Documents Department
University of Chicago Laboratory of Molecular Structure and Spectra Technical Report: 1961

University of Chicago Laboratory of Molecular Structure and Spectra Technical Report: 1961

Date: 1962~
Creator: University of Chicago. Laboratory of Molecular Structure and Spectra.
Description: Report containing articles, manuscripts, and tabulations of recorded spectra created by the Spectroscopic Laboratory of the University of Chicago.
Contributing Partner: UNT Libraries Government Documents Department
University of Chicago Laboratory of Molecular Structure and Spectra Technical Report: 1968

University of Chicago Laboratory of Molecular Structure and Spectra Technical Report: 1968

Date: 1969~
Creator: University of Chicago. Laboratory of Molecular Structure and Spectra.
Description: Report containing articles, manuscripts, and tabulations of recorded spectra created by the Spectroscopic Laboratory of the University of Chicago.
Contributing Partner: UNT Libraries Government Documents Department
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