Correlation of optical parameters of pure and doped Ge17Sb8Se75-xErx chalcogenides films using transmission spectra

Abstract

Six compositions of erbium (Er) doped Ge17Sb8Se75-xErx(x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) chalcogenide bulk have been synthesized by melt quenching technique. Further, systematic studies of chemical composition based optical parameters via Inverse synthesis methods have been carried out. Thin films of these chalcogenides have been deposited using thermal evaporation technique (∼10−4 Pa) on the microscopic glass substrate which are found to be amorphous. Transmission spectroscopy carried out in the range 400–2000 nm has been used as the signature of these compositions to calculate various optical parameters. Further, inverse synthesis method is used to estimate the refractive index (n), extinction coefficient (k), and thickness (d) of thin film. In the strong absorption region, absorption coefficient is calculated with the help of method suggested by Connel and Lewis. The systematic compositional dependency on Er doped has been established with refractive index and band gap of chalcogenide glasses. The refractive index dispersion is also discussed in terms of the single oscillator using the Wemple-Di Domenico model. The chemical composition dependent parameters such as dispersion energy, oscillator energy have been calculated to understand the order parameter.