Vacuum Annealing and in-Situ XPS Measurement of Oxidized Sn Films

The dependence of chemisitry properties of elements Sn and O on the surface of oxidized Sn films on vacuum annealing was studied. By usillg in-situ measurements of X-ray photoelectron spectroscopy (XPS), it was found that great number of negatively charged particles (such as O- and O2) were adsorbed on the surface. The amount of the adsorbed oxygen particles increased with the annealing temperature (Tann), and then the adsorbed oxygen particles became less charged.The increase in the number of the adsorbed oxygen particles is attributed to the transition from SnO2 to Sn2O3 as Tann 5350℃. At 350 Tann 400℃, the relative content of Sn in metallic Sn phase increased suddenly with Tann due to the transition from Sn3+ to Sno, which resulted in releasing and successively piling up of O particles adsorbed on the surface. Aloreover, SnO2 became more stable than Sn2O3 in the case of higher annealing temperauters, as say Tann 250℃. The adsorbed states of the oxygen Particles on the surface and the correlation between the adsorbed states and annealing temperature were also discussed.