Effect of Pb Addition on Optical and Spectral Properties of Se–Ge Thin Films

Abstract—The present paper reports the optical and spectral properties of amorphous Se₅₈Ge_{42 – x}Pb_x (x = 6, 12, 18, 20) thin films deposited onto pre-cleaned glass substrate under a vacuum of 10^–5 Torr. The amorphous samples have been prepared using melt quenching method. The structural characterization of the samples has been done using XRD and EDXA. The optical absorption and transmission spectra were recorded using UV-Vis spectrophotometer in the wavelength range 400–2500 nm. The study of absorption spectra shows that sample exhibits indirect optical band gap which decreases on increase of Pb content in Se–Ge system. This decrease in band gap has been explained in terms of chemical bond approach and density of state model. Transmission spectra have been utilized to obtain refractive index, dielectric constant and thickness of films. It is found that refractive index increases with increase in Pb content in Se–Ge system.