Temperature dependence of the optical properties of thin Ge-Se-In films

Abstract

This paper deals with the properties of the glasses and thin films from multi-component chalcogenide prepared by co-evaporation technique. The thin chalcogenide layers from the Ge30Sе70−xInx system were deposited by thermal co-evaporation of bulk glasses from Ge-Se system and In2Se3. Using X-ray microanalysis it was found that the film compositions are close to the expected ones. The refractive index, n, and the optical band gap, Egopt, were determined by spectral ellipsometric measurements. The thin film's structure was investigated by Raman spectroscopy.The temperature coefficients of the linear thermal expansion, αl and the band gap, βEg were determined. Decrease of the values of αl from 2.49 × 10−4 K−1 to 4.55 × 10−5 K−1 and βEg from −1.3 × 10−3 eV·K−1 to −0.7 × 10−3 eV·K−1 was observed when indium content in the thin films was increased from 0 to 17 at.%.