Rebonding of Se to As and Ge in Ge33As12Se55 films upon thermal annealing: Evidence from x-ray photoelectron spectra investigations

We have measured and analyzed x-ray photoelectron spectra XPS of as-grown and annealed Ge33As12Se55 films compared with bulk material. We found that the as-grown film contains a large number of separated Se clusters which can coalesce with As and Ge after annealing at high temperatures. In addition, both the Ge and As 3d spectra show the presence of oxides. While the Ge oxidation increases with an increasing annealing temperature, As oxidation is almost unaffected by annealing. The difference could be due to their different electro-negativities. Our results suggest that, while thermal annealing is effective to move the film toward the bond structure of bulk glass, the simultaneous surface oxidation must be suppressed in order to achieve high quality films. © 2007 American Institute of Physics. DOI: 10.1063/1.2737785