Local surface structure and structural properties of As-Se nanolayers studied by synchrotron radiation photoelectron spectroscopy and DFT calculations

The surfaces of As20Se80, As40Se60 and As50Se50 films were studied using synchrotron radiation photoelectron spectroscopy and DFT electronic structure calculations. The composition and local structure of the surfaces were determined by curve fitting of the experimental As 3d and Se 3d core levels, and studies show significant Se-enrichment in the top surface layers of the films. The valence band spectra have been interpreted within a model of discrete structural units, giving rise to distinct peaks in the spectra. The interconnection between the surface composition, local structure formation and the features of the valence band spectra of As20Se80, As40Se60 and As50Se50 films is analyzed and discussed in detail.