Optical behaviors of thin indium-containing chalcogenide films

The optical spectra of thin (GeSe5)100−xInx films, with x from 0 to 20 mol% indium, have been studied with a view to understanding the role of indium on the film behavior. An optical characterization method, based on the transmission and the reflection spectra at normal incidence of uniform, thin films, has been used to obtain the thicknesses and optical constants corresponding to the as‐deposited and annealed samples. The dispersion of the refractive index is discussed in terms of the single‐oscillator Wemple‐Di Domenico model. The absorption edges are described using both the Urbach rule and the ‘nondirect transition’ model proposed by Tauc. The variations in the refractive index, the bandgap, and the oscillation energy of the films after annealing are discussed with respect to rearrangement of the main structure units. Copyright © 2010 John Wiley & Sons, Ltd.