The effect of Ge addition on the optical and physical properties of thermally evaporated amorphous Pb15Se85-xGex (x = 0, 3, 6, 9, 12) thin films and bulk glasses

Abstract

The effects of the addition of Ge on the optical and physical properties of a-Pb15Se85-xGex (x = 0, 3, 6, 9, 12 at. %) vacuum evaporated thin films are discussed in the given paper. An X-ray diffraction analysis of the films reveals no sharp peaks, indicating their amorphous nature. Transmission spectra of normal incidence were measured in the spectral window of 500 nm–2400 nm. An absorption edge shift has been observed with the addition of Ge at the expense of Se. Swanepoel analysis was applied to compute the refractive index values. Absorption losses were also calculated and discussed. The increase in Ge addition changes the refractive index and absorption coefficient. The bandgap transition is indirect and experimentally calculated using the Tauc-extrapolation method. Penetration depth and optical density were also calculated. WDD model was applied and static refractive index and WDD parameters were evaluated. Theoretical parameters viz. Cohesive energy, average heat of atomization, compactness, polaron radius were also calculated. Efforts were made to correlate obtained optical and physical parameters of the system.