Peculiarities of valence band formation in As-Ge-Se semiconductor glasses

Peculiarities of valence bands formation in As-Ge-Se semiconductor glasses have been investigated within AsxGexSe₁₋₂x cut of glass forming region by highresolution X-ray photoelectron spectroscopy (XPS). It is shown that compositional dependence of XPS valence band spectra of the investigated glasses correlates well with previously obtained data for constituent glasses of binary GexSe₁₋x and AsxGe₁₋x systems. In particular, increase in х leads to the decrease in the intensity of bands at ~2 eV responsible for Se lp-states. The valley at ~3 eV is filled by electronic states originated from Se-GE and Se-As bonds. An accompanying decrease in the intensity of the band at ~5 eV is explained by a decrease in Se 4p bonding states associated with covalent bonds

High-resolution XPS for determining the chemical order in chalcogenide network glasses

The power of X-ray photoelectron spectroscopy (XPS) measurements and analysis is demonstrated to establish the structure of network glasses using the examples of binary As-Se, As-S, Ge-Se and Ge-S series. Short-range chemical order in these materials is established, and main building blocks of their structurally-disordered glass network are identified throughout respective glass-forming compositional domains. The XPS fitting procedure is correlated with disproportionality analysis based on the conditions of chemically-ordered bond network model and uniform distribution of constituent chemical elements. The structure of binary As-based glasses (As-Se and As-S) is shown to be adequately described by the terms of ‘chain-crossing’ model, while ‘outrigger raft’ model has to be additionally used to build a network of Ge-based glasses (Ge-Se and Ge-S)

Cooperative rearranging region size and free volume in As–Se glasses

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