Ellipsometric and Spectrometric Studies of (Ga0.2In0.8)2Se3 Thin Film

Abstract

Thermal evaporation technique is used to deposite (Ga0,2In0,8)2Se3 thin films. The refractive index and extinction coefficient dispersions are obtained from the spectral ellipsometry measurements. The dispersion of the refractive index is described in the framework of the Wemple–Di Domenico model. The optical transmission spectra of a (Ga0,2In0,8)2Se3 thin film are studied in the temperature range 77–300 K. The temperature behavior of the Urbach absorption edge, as well as the temperature dependences of the energy pseudogap and Urbach energy, are investigated. The influence of different types of disordering on the optical absorption edge of a (Ga0,2In0,8)2Se3 thin film is discussed. Optical parameters of a (Ga0,2In0,8)2Se3 thin film and a single crystal are compared.