CU(IN,GA)SE-2 THIN-FILMS AND SOLAR-CELLS PREPARED BY SELENIZATION OF METALLIC PRECURSORS

CuIn(1-x)GaxSe2 (CIGS) thin films with Ga ratio, x, ranging from 0.55 to 0.75 were grown on Mo/glass substrates by the selenization of metal lic precursors in a H2Se atmosphere. Without a postdeposition annealin g step the films were found to have a highly graded composition that b ecame Ga rich near the absorber/Mo interface. A high-temperature annea ling step promoted diffusion of Ga to the surface region of the films. These absorbers were used to fabricate glass/Mo/CIGS/CdS/ZnO thin-fil m solar cells with open-circuit voltages ranging from 0.4 to 0.74 V an d efficiencies approaching 12%. Devices, as well as the absorber layer s, were characterized. (C) 1996 American Vacuum Society.