Photoinduced changes in the electronic structure of As4Se3 glass

We have sought within the electronic structure, the origin of photoinduced reversible effects in chalcogenide glasses by measuring core-level and valence band X-ray photoelectron spectra (XPS). The reversible and permanent photoinduced changes are separated by recording the spectra before, during, and after the sample was exposed, in situ, to bandgap laser light. Previous work on As2Se3 bulk glass indicated that oxygen may play a catalytic role in these observed changes. We now report results of laser irradiation on an oxygen-free As4Se3 film that was prepared by thermal evaporation within the XPS chamber. The experimental results of core level peaks support the first principles molecular dynamics simulation with 224 atoms and provide insight into the photoinduced structural changes.