Investigation of the structure of GexAsySe1-x-y glasses by x-ray photoelectron spectroscopy

We have measured and analyzed x-ray photoelectron spectra of a series of GexAsySe1-x-y glasses. The valence band spectra show that a number of Se-rich structures exist in the samples. After decomposing Ge, As, and Se 3d spectra into several doublets and assigning them to the different local bond structures, it was found that, while GeSe4/2 tetrahedral, AsSe3/2 pyramidal, and Se trimers decrease in their integrated areas, most defect bonds increase with increasing mean coordination number. Moreover, while the appearance of Se trimers is reasonable in Se-rich samples, they never vanish, even in Se-poor samples. A possible mechanism to form Se trimers in Se-poor samples is discussed. (c) 2008 American Institute of Physics.