Optical and Electrical properties of ZnS thin films prepared by spray pyrolysis

Zinc Sulfide semiconductor ceramics, a II-VI group semiconductor materials possessing a high direct band gap about 3.66 (eV) in the near-UV region, are currently being intensively studied by material scientists, physicists and chemists due to their multifaceted applications especially in opto-electronic devices. In this report, thin films of ZnS were deposited on the well-cleaned glass and silicon substrates at various substrate temperatures through a simple and low cost spray pyrolysis technique. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Ultraviolet-Visible (UV-Vis) spectroscopy were used to investigate the effect of substrate temperature on some structural features and optical properties of the ZnS thin films. It was found that at the lowest substrate temperatures (300 ◦C) the ZnS films are almost amorphous form. With increasing substrate temperature, the crystalline quality was improved. The surface morphology of the ZnS films prepared at high temperatures is relatively more homogeneous and dense with no cracks also optical characterization revealed that as-prepared thin films show optical transmittance more than 95% in visible range. In the following, we have examined the opto-electrical properties of ZnS thin films as a function of substrate temperature and realized that the high substrate temperature and good crystallinity strongly affect subsequent opto-electronic properties.