Photoinduced and Thermally-Induced Bleachings of Amorphous Ge–S Film

Photobleaching and thermal-bleaching of Ge35S65 film were studied on the basis of kinetics for blue shift of optical transmission edge, oxygen depth profiles and far infrared transmission spectra. This study suggests that the photobleaching is associated with both photoinduced intrinsic structural change in the film and photo-oxidation of Ge atom around the film surface. In the early stage, the photobleaching is mainly caused by the photoinduced structural change. The photo-oxidation proceeds gradually and becomes significant in the case of a prolonged illumination in air. It was confirmed, on the other hand, that thermal-bleaching is due to thermal polymerization.