Effect of substrate temperature on structure and optical properties of ZnS thin films deposited by electron-beam evaporation

ZnS thin films have been deposited on silicon substrates by electron-beam evaporation technique at different substrate temperatures. The crystal structure, surface morphology and optical properties of ZnS films were characterized by X-ray diffractometer (XRD), atomic force microscope (AFM), optical spectrophotometer and thickness gauge. The effects of substrate temperature on structure and optical properties of films were investigated. The results showed that the films grown at these temperatures exhibited zinc blende structure (β-ZnS). As the of substrate temperature increasing, the films were highly (111) preferred orientation, and grain size increased. In addition, intrinsic stress, dislocation density, refractive index and absorption coefficient decreased as substrate temperature increasing, while optical band gap increased. The surface morphology of ZnS thin film at 300°C was uniform and compact, presenting the better structural and optical properties.