Abstract
The effect of thermal annealing process on both structural and optical properties of amorphous As(47.5)Se(47.5A)g(5) thin films was studied. The X-ray diffraction studies exhibit that the crystallinity was improved by increasing the annealing temperature. Further, the crystallite size and the crystallinity increase whereas dislocation density and strain decrease with increase of annealing temperatures. The optical constants of the as-prepared and annealed of As(47.5)Se(47.5A)g(5) thin films were calculated using envelope method. The optical absorption data in these films were successfully describes by Tauc's relation which exhibit the indirect transitions for as-prepared sample and allowed direct transition for annealed sample above onset temperature T-c. It is evident that the energy gap E-g(opt) decreases and the localized states E-e increases as a function annealing temperature. The dispersion of the refractive index n for these films was discussed using the single oscillator model proposed by the Wemple-DiDomenico relationship.