Optical study of Ge10Se90-xTex glassy semiconductors

Chalcogenide glasses are interesting materials from their infrared transmitting properties and photo-induced effects exhibited by them. Thin films of the glasses Ge10Se90-xTex (x = 0, 10, 20, 30, 40, 50) prepared by melt quench technique were evaporated at a pressure of ∼ 10-4 Pa. The amorphous nature of bulk as well as thin films was detected by X-ray diffraction. Optical transmission spectra of thin films were obtained in the range 400-2400 nm. The optical constants i.e. optical band gap, absorption coefficient and refractive index are calculated using the Swanepoel method. The optical band gap is found to decrease with the increase of Te content. The absorption coefficient and refractive index decrease with the increase of wavelength. The refractive index first decreases (up to 30 at.%) and thereafter increase with Te content