Structural, morphological and optical properties of sprayed ZnS thin films on various substrate natures

ZnS thin films have been deposited on various types of substrates by spray pyrolysis technique. These films were grown only at 400 °C because at this temperature the films became near stoichiometric ZnS material and the crystallinity improves. In order to study the influence of nature substrate on the properties of ZnS thin film, the layers were investigated using X-ray diffraction, Atomic force microscope and optical transmittance spectroscopy to evaluate the quality of the layers for photovoltaic applications. Studies were done on thin films deposited on glass, pyrex, quartz and silicon. It is found that for the films deposed on silicon, (about 1 μm thick) have good adherence and exhibit a mixture of hexagonal (α) and cubic (β) phases, with a preferential orientation along the (1 0 3)α direction. UV–vis optical measurements analysis showed that these binary films have a relatively high absorption coefficient (≈105 cm−1) in the visible spectrum ZnS films deposed on quartz. An analysis of the deduced spectral absorption of the deposited films revealed direct band gap energy of 3.47–3.70 eV for ZnS layers with varying the substrate nature. The AFM data revealed that the films were homogenous. The other structural and optical parameters such as disorder, refractive index and optical gap were also evaluated.