Electrodeposition of Polycrystalline and Amorphous Silicon for Photovoltaic Applications. Final Report, June 11, 1979-September 10, 1980

摘要

Silicon was electrodeposited on metal substrates using two markedly different conditions. Polycrystalline deposits were obtained from K sub 2 SiF sub 6 dissolved in high temperature (> 700 exp 0 C) molten fluoride salts. The deposits produced at temperatures below 80 exp 0 C from organo- and halo-silanes as silicon precursors in propylene carbonate electrolytes had an amorphous structure. Because the technology of electroplating silicon is largely undeveloped, a major emphasis was given to the electrochemical characterization of the plating baths and the relationship between the deposition conditions and the resulting deposits. The results with FLINAK (LiF (46.5%), KF (42.0%) and NaF (11.5%)) and the binary mixture LiF (50%) : KF (50%) as the molten salts for Si deposition were comparable. Cyclic voltammetry (CV) using a three-electrode configuration was done on the melts before and after addition of the silicon precursor. The amorphous silicon was deposited from propylene carbonate which had been dried over alumina. The best supporting electrolytes were tetrabutylammonium perchlorate and tetrafluoroborate. The silicon precursors investigated were SiHCl sub 3 , SiHBr sub 3 , SiCl sub 4 , (ClC sub 3 H sub 6 )SiCl sub 3 , Si(OEt) sub 4 and (CH sub 3 ) sub 3 SiCl. Information on the chemical composition of the films was obtained from IR and Auger spectroscopy. (ERA citation 06:030139)