Abstract
The optical properties of Se-Te thin films deposited on glass substrates by vacuum evaporation technique were studied. The amorphous nature of thin films was detected by X-ray diffraction. The optical properties of thin films have been studied in the wavelength range 200-800 nm. The mechanism of optical absorption follows the allowed 'non-direct electronic transition' model proposed by Tauc. It was found that the optical band gap E-g decreases while the width of localized states (Urbach energy) E-c increases as Te content increases.