Synchrotron XPS studies of illuminated and annealed flash evaporated a-Ge2S3 films

The atomic composition, local structure and coordination of flash evaporated Ge2S3 films and their changes induced by laser illumination and thermal annealing in vacuum were investigated by means of high resolution synchrotron radiation and X-ray photoelectron spectroscopy. The top surface and subsurface layers of the films are found to be enriched by Ge in comparison with the composition of target glass and contain oxygen and a significant contribution of physisorbed carbon. The influence of laser and thermal treatments of flash evaporated Ge–S films in vacuum on their composition is analyzed. The local atomic coordination obtained by curve fitting of Ge 3d, S 2p, O 1s and C 1s core level spectra is discussed in detail.