Microscopic Origins of Metastable Effects in a-Si:H and Deep Defect Characterization in a-Si,Ge:H Alloys: Final Subcontract Report, 1 February 1991 - 31 January 1994

Technical Report · Thu Sep 01 00:00:00 EDT 1994

DOI:https://doi.org/10.2172/10183684· OSTI ID:10183684

Cohen, J. D.

This research supported by NREL Subcontract XG-1-10063-1 over the past three years has involved, first of all, a fairly complete characterization of a two series of a-Si{sub 1-x}Ge{sub x}:H samples: a series of 9 films grown at the University of Delaware by the photo-CVD method (for 0.29 {<=} {times} {<=} 0.62) and series of 6 films grown at U.S.S.C. by the glow discharge method (for 0.20 {<=} {times} {<=} 0.50). Both these series of samples seem to represent what is close to the {open_quotes}state-of-the-art{close_quotes} in current a-Si,Ge:H alloys. The authors detailed comparison of the properties of the glow discharge material with the photo-CVD samples show remarkable similarities rather than significant differences. In particular, measurements of these samples: (1) allowed the assignment of defect energy levels from a detailed analysis of transient sub-band-gap photocapacitance and photocurrent spectra. (2) The authors found the density of deep defects to increase exponentially with the germanium content. (3) The authors found that the trapping lifetimes related {mu}{tau} products for holes decrease in direct proportion to the density of midgap defects in these samples, at least up to Ge fractions of 50at.%. (4) The authors have also made significant progress toward identifying both the optical and thermal defect transitions in the a-Si,Ge:H alloys.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 10183684
• Report Number(s): NREL/TP-451-7163; ON: DE94011887
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
140501
360602
CHEMICAL VAPOR DEPOSITION
CRYSTAL DEFECTS
defect characterization
ENERGY LEVELS
FILMS
germanium
GERMANIUM ALLOYS
HYDRIDES
hydrogenated amorphous silicon
IMPURITIES
metastability
PHOTOVOLTAIC CONVERSION
photovoltaics
PROGRESS REPORT
SILICON
SILICON ALLOYS
solar cells
STRUCTURE AND PHASE STUDIES