Structural, Swanepoel’s method, optical and electrical parameters of vacuum evaporated Zn50Se50 thin films

Thin films of Zn50Se50 were prepared by the vacuum evaporation technique on glass substrates. The influence of annealing temperature (Tann.) on the structural and optical properties of ZnSe polycrystalline films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical transmittance T (λ). The crystalline phases that were found in the Zn50Se50 thin films are ZnSe, Se and Zn. The refractive index (n) and the thickness of the films (d) were calculated using Swanepoel’s method for the films annealed at (423 K). The mechanism of optical absorption follows the rule of direct transition. The values of band gap (EG) were found to decrease from about 2.933 to 2.635 eV with the increasin of the Tann. from 300 to 423 K. Urbach energy (EU) was calculated and found to the increase by increasing Tann. The dispersion of the n was discussed in terms of the single-oscillator Wemple and DiDomenico model. The Arrhenius formula was used to discuss the electrical conductivity (σDC), activation energy (ΔE) and preexponential factor (σo).