Abstract
Amorphous Se96Te4 and Se94Te4Ga2 thin films were prepared onto glass substrates by using thermal evaporation method. The changes in the optical properties ( optical band gap, absorption coefficient, and extinction coefficient) have been measured in the wavelength range 350-900 nm by a spectrophotometer. These thin films are irradiated by pulsed nitrogen laser up to similar to 7min. Optical band gap, extinction coefficient and absorption coefficient of these films have been studied before and after laser irradiation. It is found that optical band gap (Eg) is decrease in both cases after laser irradiation on thin amorphous film and increase by addition of Ga.