Surface oxidation of Ge33As12Se55 films

Ge33As12Se33 films deposited by ultrafast pulse laser deposition were annealed at various temperatures and pressures, and the dependence of the surface oxidation on the processing conditions was investigated by X-ray photoelectron spectroscopy (XPS). We found that even as-grown film contains a thin oxidized surface and the oxygen distribution exponentially decays along the normal direction of the films regardless of different processing conditions. The critical thicknesses of the oxidized layers were 6.5, 11, 48, and 98 nm, respectively, for the as-grown, 250°C annealing sample for 4 h under 1-10-6 Torr, and 150° and 250°C annealing samples for 15 h under 20 mTorr.