The most significant process for optical coating is the variant of vacuum deposition. Zinc sulfide having direct and large band gap which is use in optoelectronics. By using ZnS material in thermal evaporation technique and characterizing the minimum reflectance and maximum transmittance in visible wavelength and energy gap increases with increasing thickness having direct and large band gap. When ZnS thin films doped with the similar material then the transmission band can be widened in IR region. On this method, we make many applications over IR windows and scintillation detectors and other electronic devices.