Synthesis of polycrystalline ZnS0.5Se0.5 layers chemical spray deposition process

Thin films of ZnS0.5Se0.5 have been - synthesised by spray pyrolysis using an aqueous solution of ZnCl2, thiourea and selenourea. The films were deposited onto glass substrates at different temperatures in the range, 250-550degreesC, keeping the other deposition parameters constant. The structure, surface topography, composition and optical properties of these films have. been investigated as a function of substrate temperature. The layers grown at temperatures <350degreesC showed secondary phases of - ZnS, ZnCl2 and Se in conjunction with A ZnS0.5Se0.5 phase. At growth temperatures above 350degreesC, all the secondary phases started to disappear favouring the formation of ZnS0.5Se0.5. Polycrystalline ZnS0.5Se0.5 films with a strong (100) orientation were grown at a temperature of 475degreesC. These layers have the wurzite crystal structure and consist of densely packed pyramid-like grains. The films have optical transmittances greater than 75 % for long wavelength photons. and the absorption edges were found to be steep. The energy band gap was found to be 3.04 eV for x = 0.5.