Structural, linear and non-linear optical properties of annealed As47.5Se47.5Ag5 thin films for optoelectronic applications

The effect of thermal annealing temperature on both structural and optical properties of amorphous As47.5Se47.5Ag5 thin films was studied. The XRD studies showed that the crystallinity of the studied films is improved by increasing the annealing temperature. Furthermore, the crystallite size increase whereas dislocation density and strain decrease with increasing the annealing temperature. The optical constants of the asprepared and annealed As47.5Se47.5Ag5 thin films were calculated using the envelope method. The optical absorption data of these films was successfully described by Tauc's relation. The optical absorption mechanism was found to follow the allowed direct and indirect transitions. In addition, it was found that the optical band gap decreases while band width E, increases as the annealing temperature increases. The data of the refractive index n was analyzed and discussed in terms of the single oscillator model proposed by Wemple-DiDomenico. Besides that, the non-linear optical parameters chi((1)), chi((3)) and n(2) were determined as a function of the annealing temperature.