Optical properties of amorphous As-Se and Ge-As-Se thin films

Abstract

Amorphous As-Se and Ge-As-Se thin films were prepared by thermal evaporation. From parameters of the Wemple-DiDomenico model, the values of the third-order non-linear susceptibility were estimated using the generalized Miller's rule. Measurements of photodarkening at 78 K showed that the optical gap and the slope of the optical absorption edge are intercorrelated. The kinetics of the photoinduced shift of the gap are described using a stretched exponential law. A possible role of the concentration of Se atoms on the rate of photodarkening on one hand and of the network rigidity (measured by the mean coordination number) on the other are briefly discussed.