X-ray photoelectron spectroscopy has been used to determine the binding energies of the core electrons in Ag-doped amorphous thin GexSb40-xS60 films (x = 15. 20. 25 and 27). Chemical shifts of the constituent elements have revealed that electrons are transferred from chalcogenide to metal and compounds such as Ag2S and Ag2O are likely to form due to photoinduced chemical modification and oxidation, respectively. Charge defects are induced in the amorphous system. (C) 2002 Elsevier Science B.V. All rights reserved.