Synchrotron investigations of the initial stage of tin nanolayers oxidation

Initial stages of thermal oxidation of metal tin nanolayers (100 nm) in the air were investigated using X-ray absorption near edge structure (XANES) technique. Analysis of the XANES data revealed that in the metal film exposed to air at room temperature an oxygen K-edge is observed. Its structureless shape indicates the formation of amorphous Sn-O phase in the surface layer. At the same time from Sn M4,5-spectra of the same tin film one can see M4,5 absorption edges characteristic of the elementary tin and for its oxide as well.The fine structure near the absorption edges for both elements (tin and oxygen) in the sample annealed at 170 °C correlates quite well and it corresponds to the results of calculations of the density of p-states for tetragonal SnO monoxide.The changes in the fine structures of O K-edge and Sn M4,5-spectra with the increase of the oxidation temperature up to 240 °C indicates the appearance of SnO2 in the nanolayers, which becomes a predominant one under the further increase of annealing temperature.