Combined high-resolution XPS and EXAFS study of Ag photodissolution in a-As2S3 thin film

Changes of electronic and atomic structure during silver photodissolution in As2S3 thin film are studied using a combination of high-resolution X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) methods. It is shown that the photodiffusion process starts already under the influence of Al Kα and synchrotron X-ray probe radiations, forming a highly disordered metastable structure. Concurrent irradiation with UV/VIS light leads to the formation of a stable uniform ternary phase. The mechanisms of structural transformations and final chemical products are proposed. The influence of surface oxidation on the structure of Ag/As2S3 bilayer is also investigated.