Structural and Optical Constants of Annealed As47.5Se47.5Ag5 Film using DSC Transformation Curve

Abstract

The effect of thermal annealing process on both structural and optical properties of amorphous As47.5Se47.5Ag5 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 As47.5Se47.5Ag5 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 Tc. It is evident that the energy gap Egopt decreases and the localized states Ee 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.