Electrodeposition of CuInS 2 from aqueous solution Part I. Electrodeposition of CuS film

Abstract

As the first stage for thin film preparation of copper indium disulfide (CuInS 2), an electrodeposition technique of thin films in the CuS system was investigated from a new viewpoint. Deposition was carried out potentiostatically on a Ti substrate from acidic aqueous solution containing CuSO 4 and Na 2S 2O 3. Tartaric acid was found to be effective as a buffer for stabilizing the hydrogen ion concentration. Thin films of Cu 2S were obtained at −0.7 V vs. Ag/AgCl with good reproducibility from a solution containing 10 mM CuSO 4, 400 mM Na 2S 2O 3 and 100 mM tartaric acid. Scanning electron microscopy and energy dispersive X-ray analyses revealed that the film deposited had a crack-free surface and uniform stoichiometry of Cu 2S. Film thickness was estimated to be 0.6−0.8×10 −6m after 3600 s deposition. The mechanism of Cu 2S formation was supposed to be that S 2O 3 2− ion reduces Cu(II) ion to make complex with Cu(I) ion. Probably it is this complex that contributes to the Cu 2S formation.