Photochemical Deposition of GaSxOy Thin Films from Aqueous Solutions

Photochemical deposition (PCD) is a technique of film preparation from solutions by UV light illumination. In this study, GaSxOy thin films were prepared on fluorine-doped-tin-oxide-coated glass substrates by PCD from an aqueous solution of Ga-2(SO4)(3) and Na2S2O3. GaSxOy is a wide-band-gap semiconductor and suitable as a buffer layer material in solar cells. The as-deposited films were characterized by Auger electron spectroscopy, scanning electron microscopy and optical transmission spectroscopy. The O/Ga ratio was close to the stoichiometric ratio, 1.5, and the S/Ga ratio is much smaller, less than 0.3 for a film deposited under the optimum conditions. The film exhibited a wide energy band gap of 3.5 eV and a resistivity of the order of 10(2) Omega cm. (C) 2010 The Japan Society of Applied Physics DOI: 10.1143/JJAP.49.062302