Effects of substrate temperature and thickness on the structural and optical properties of ZnS thin films prepared by PVD method

ZnS films were deposited on glass substrates by physical vapor deposition (PVD) at two different filmthicknesses of 75nm and 200nm. Substrate temperature was varied from 75 0C to 200 0C . Structural and optical propertiesof the films were investigated by X-Ray Diffraction (XRD), UV-VIS-NIR spectrophotometery and Raman spectroscopy.Experimental results show that the as- deposited ZnS thin film at thickness of 75nm exhibit cubic structure but withincreasing thickness to 200nm , We can see a ZnS films show cubic structural accompanied with some aspect of wurtzitephases . By increasing either substrate temperature or film thickness, the crystallinity would improve, additionally theband gap energy and also grain size increased .The average optical transmission of films at wavelengths longer than 400nm is more than 80% and a little variation in transmittance, accompanied with shift to shorter wavelength of absorptionedge is clear due to the effect of the substrate temperature andthickness.

Keywords:

ZnS thin films , optical properties , structure , substrate temperature , thickness