A SIMPLE AND LOW-COST TECHNIQUE FOR ELECTROLESS DEPOSITION OF CHALCOGENIDE THIN-FILMS

A simple and economical electroless chemical deposition technique for deposition of several metal sulphides and selenides is presented. Aqueous solutions of metal salts and of sodium thiosulphate or sodium selenosulphate were used for the chemical bath. The technique is based on hydrolytic decomposition of the various metal-thiosulphate or metal-selenosulphate complexes in aqueous media, at a suitable temperature, concentration and pH. The technique presented in this paper has been successfully used for deposition of Cu2S, CuS, PbS, Sb2S3 and Sb2-xBixS3 in acidic media, and Ag2S, Cu2Se and PbSe in alkaline media, on various substrates, such as glass, metal, plastics, alumina, silicon and sapphire. Depending on the deposition time and the individual system, films of thicknesses up to 0.3 mum were obtained from a single bath. The prospects of this technique are very good for multilayer combinations, solid solutions, and possibly ternary compounds as well. This technique was found to be suitable for any size and shape of substrate. It is a non-polluting and economical technique, since the bulk precipitates are of a relatively high purity and can be used as semiconducting powders, mineral pigments etc. The optimal conditions for deposition of each kind of film are described and the corresponding x-ray diffraction patterns are presented. Optical spectra in the wavelength interval between 300 and 2500 nm for each of the films are also supplied. The sheet resistivity and type of conductivity for each kind of film have also been determined.