Effect of oxygen on the photoinduced changes in the electronic structure of As50Se50 glass films

The effect of ambient on photoinduced changes in the electronic structure of As50Se50 chalcogenide glass was investigated using high resolution X-ray photoelectron spectroscopy (XPS). As50Se50 films were deposited on Si substrate in the vacuum of the spectrometer, and then irradiated under bandgap laser light in situ as well as ex situ in air. Very little difference was observed in the XPS spectra of the as deposited film before and after in situ irradiation. However, ex situ irradiation of the film in air showed changes in the chemical environment of both elements, and an enrichment of the surface with oxygen and Se, but depletion of As. The depth profile of these changes, as obtained by angle resolved XPS, describes the light-induced reaction with oxygen, The new results point to a crucial role of oxygen in photoinduced structural changes.