Substrate-temperature-dependent structural and optical properties of ZnSe thin films fabricated by using an electron beam evaporation technique

Zinc-Selenide (ZnSe) thin films were prepared by using physical vapor deposition under a vacuum of 5 × 10^-6 Torr by using an electron beam evaporated technique at different substrate temperatures, RT, 100, 200, and 300 °C. X-ray diffraction analysis (XRD) indicates that the films are polycrystalline, having a f.c.c zincblende structure irrespective of their substrate temperature. All the films show preferred orientation along the (111) plane parallel to the substrates. The microstructural parameters, such as the lattice constant, crystallite size, stress, strain, and dislocation density, are calculated, and the effect of substrate temperature on the deposited films was discussed. The grain size of the deposited ZnSe films is observed to be small and is within the range of 12 to 32 nm, and the grain size is observed to be increase from 12.5 to 31.9 nm with increasing substrate temperature. Optical measurements indicate the existence of a direct-bandgap-allowed optical transition with a corresponding energy gap in the range of 2.95-2.70 eV.