ELECTRODEPOSITION OF CUINS2 FROM AQUEOUS-SOLUTION .1. ELECTRODEPOSITION OF CU-S FILM

As the first stage for thin film preparation of copper indium disulfid e (CuInS2), an electrodeposition technique of thin films in the Cu-S s ystem was investigated from a new viewpoint. Deposition was carried ou t potentiostatically on a Ti substrate from acidic aqueous solution co ntaining CuSO4 and Na2S2O3. Tartaric acid was found to be effective as a buffer for stabilizing the hydrogen ion concentration. Thin films o f Cu2S were obtained at -0.7 V vs. Ag/AgCl with good reproducibility f rom a solution containing 10 mM CuSO4, 400 mM Na2S2O3 and 100 mM tarta ric acid. Scanning electron microscopy and energy dispersive X-ray ana lyses revealed that the film deposited had a crack-free surface and un iform stoichiometry of Cu2S. Film thickness was estimated to be 0.6-0. 8 x 10(-6) m after 3600 s deposition. The mechanism of Cu2S formation was supposed to be that S2O32- ion reduces Cu(II) ion to make complex with Cu(I) ion. Probably it is this complex that contributes to the Cu 2S formation.