Rare‑earth (Dy)‑doped ( GeS2)80(In2S3)20 thin film: influence of annealing temperature in argon environment on the linear and nonlinear optical parameters

Abstract

We report the optical properties of thermally evaporated rare-earth (Dy) doped ( GeS2)80(In2S3)20 thin film. Film of thickness 1100 nm has been deposited on a microscopic glass slide, and the as-prepared thin film has been characterized using X-ray diffraction, energy dispersive spectroscopy and UV–visible–near infrared spectroscopy. With annealing temperature, the refractive index is noticed to decrease from 2.51 to 2.27, while the optical bandgap is observed to increase from 2.03 to 2.29. The dispersion of the refractive index n for as prepared and annealed thin films have discussed using the single oscillator model proposed by the Wemple–Di Domenico relationship. The observed value of Eo (5.31–4.40 eV) and dispersion energy Ed (28.22–18.18 eV) are decreasing for as prepared and annealed thin films. The increase of bandgap has been explained in terms of the disorder in the system.