Deposition of transparent and electroconductive chalcogenide films at near-room temperatures

Abstract An economic and pollution-free technique for electroless chemical deposition of transparent and electrically conductive sub-micron films on the surfaces of glass, ceramics, transparent polyester films, metal, and ferroelectric thin films has been developed. The technique is based on hydrolytic decomposition of metal-thiosulfate or metal-selenosulfate complexes in aqueous solutions, and has been successfully used for deposition of transparent and electroconductive copper sulfide and copper selenide thin films of a variable composition. The basic optical and electrical characteristics of the as-deposited and annealed films are also reported. The Cu2S films were highly transparent (≥ 80 %) throughout the visible and near-infrared region of the electromagnetic spectrum (0.5 to 2.5 μm wavelength), while the rest of the films exhibited stoichiometrically adjustable absorbance in the near-infrared region (0.7 to 2.5 μm wavelength). The sheet resistivities of the films were found to be between 15 and 1200 Ω/sq. The most conductive among the chalcogenides were the Cu2Se films with sheet resistivities, R, of ∼ 15 Ω/sq., while the Cu2S films were the least conductive (R ∼ 1200 Ω/sq.).