Thin Film Cadmium Telluride, Zinc Telluride, and Mercury Zinc Telluride Solar Cells: Annual Subcontract Report, July 1, 1988-June 30, 1989.

摘要

This report covers the first year of a program to investigate (1) the deposition of CdTe films by various techniques, (2) the deposition of transparent conducting semiconductor (TCS) films by various techniques, (3) the preparation and evaluation of thin-film CdTe solar cells, and (4) the deposition and characterization of ZnTe films and heterojunctions. CdTe films were deposited on glass and SnO(sub 2)/glass substrates by metal-organic chemical vapor deposition (MOCVD) by reacting dimethylcadmium (DMCd) with diisopropyltellurium (DITe) in H(sub 2). The optical bandgap was 1.50 eV. The conductivity type of the films could be controlled by controlling the DMCd/DITe molar ratio in the reaction mixture. This is a promising technique for the preparation of thin-film CdTe homojunction solar cells. CdS films were deposited from aqueous solutions by reacting thiourea and cadmium acetate in an ammonical solution. The films show good optical transmission in the above-bandgap region but are porous and impure. The photovoltaic characteristics of cells employing solution-grown CdS films are therefore inferior to those employing vacuum-evaporated CdS films. Films of ZnO, ZnS, and ZnTe were deposited, via MOCVD, on glass and SnO(sub 2)/glass substrates, and ZnO/ZnTe heterojunctions were produced. Open-circuit voltages of 0.6--0.7 V were measured for ZnS/ZnTe heterojunctions. 14 refs., 21 figs., 3 tabs.