PROBLEM TO BE SOLVED: To inexpensively obtain the compd. semiconductor useful as a photoelectric transducer device and consisting of a metal sulfide by dipping a substrate in an aq. soln. contg. the metal ions to form a compd. semiconductor such as CdS, ZnS, Cu2S, SnS and CuInS2 and a thiosulfate ion and irradiating the substrate with UV to bring about a photochemical reaction.
SOLUTION: A substrate dipped in an aq. soln. prepared by dissolving 2 mM of cadmium sulfate and 100 mM of sodium thiosulfate in pure water is irradiated with the light from a mercury lamp to form a compd. semiconductor of CdS by photochemical deposition. The absorption edge of the aq. soln. is close to 300 nm. Only the shortest wavelength of about 250 nm of the mercury lamp is absorbed by the soln. Consequently, the S2O32- ion is excited to dissociate S, a Cd2+ ion reducing electron is separated to form CdS which is deposited on the substrate as a heterogeneous nucleation field. By this method, a sulfide semiconductor film is controlled by the light and deposited on an optional substrate.