Structure, composition and optical properties of ZnS thin films prepared by spray pyrolysis

Thin films of zinc sulfide (ZnS) are prepared by spray pyrolysis using mixe d aqueous solutions of ZnCl2 and thiourea. The structure, surface morpholog y, chemical composition and optical properties of these films are investiga ted as a function of substrate temperatures T-s, deposition times t(d) and solution spray rate s. These parameters are optimized in order to obtain fi lms with a good crystalline quality and high transmittance. It is found tha t the films prepared at substrate temperature of 500 degreesC, deposition t ime of 35 min (about 1 mum thick) and solution spray rate of 5 ml min(-1) h ave good adherence to the glass substrates and exhibit a mixture of hexagon al (alpha) and cubic (beta) phases, with a preferential orientation along t he (1 1 1)(beta) direction. The X-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA) show that the optimized films contained very little oxygen and is nearly stoichiometric. These films also show an optical transmittance more than 70% in the visible range. (C) 2001 Elsevier Science B.V. All rights reserved.