An Optical study of Amorphous (Se80Te20)100−xGex thin films using their Transmission Spectra

Abstract

Optical constants (refractive index and extinction coefficient) have been studied for a-(Se80Te20)100−xGex (x = 0, 2, 4, 6) thin films using transmission spectra in the wavelength range 500–2500 nm. It is observed from optical transmission measurements that the optical energy gap (Eg) increases while the refractive index (n) and the extinction coefficient (k) decrease with the incorporation of Ge in the Se–Te system. The increase in the optical energy gap is interpreted by correlating the optical energy gap with the decrease in electronegativity and increase in the heat of atomization (Hs). The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple–DiDomenico model.