Structure of Se-rich As-Se glasses by high-resolution x-ray photoelectron spectroscopy

Abstract

To establish the validity of various proposed structural models, we have investigated the structure of the binary As x Se 100−x chalcogenide glass family ͑x ഛ 40͒ by high-resolution x-ray photoelectron spectroscopy. From the composition dependence of the valence band, the contributions to the density of states from the 4p lone pair electrons of Se and the 4p bonding states and 4s electrons of Se and As are identified in the top part of the band. The analysis of Se 3d and As 3d core-level spectra supports the so-called chain crossing model for the atomic structure of Se-rich As x Se 100−x bulk glasses. The results also indicate small deviations ͑ϳ3-8%͒ from this model, especially for glass compositions with short Se chains ͑25Ͻ x ഛ 40͒. For example, the presence of As-As homopolar defect bonds in the stoichiometric As 40 Se 60 and of Se-Se-Se fragments in a glass with composition x = 30 is established.

Evolution of chemical structure during silver photodiffusion into chalcogenide glass thin films

“…The experimental error in the peak position and area of each component was ±0.05 eV and ±2 %, respectively. More detailed description of fitting procedure can be found elsewhere [15].…”

Electron beam-induced mass transport in As–Se thin films: compositional dependence and glass network topological effects

“…Also, according to the results presented in [28], rigidity percolation occurs near As 0.28 Se 0.72 composition in As-Se system for bulk glasses, giving additional rise to the high flexibility of glass network and mobility of it constituents, atoms and floppy clusters under the driving forces of build in gradients of chemical potential, mechanical and electric fields. Concerning to the structure of As-Se glasses, we can note 'chains crossing model', which was recently proposed in the case of Se-rich compositions like As 0.2 Se 0.8 and As 0.3 Se 0.7 glasses [37]. Based on the elastic response of ChG, their structural connectivity and rigidity reveals floppy, intermediate and stress-rigid phases [28].…”

Free-volume correlations in positron-sensitive annihilation modes in chalcogenide vitreous semiconductors: on the path from illusions towards realistic physical description

“…Thus, the positron trapping centers in ChVS possess a specific structure being composed of geometrical free volumes surrounded by free-volume shell of BFSA, the input of latter being decisive. [3,8,37], this fully explains the observed compositional variation in defect-related positron lifetimes τ 2 [7]. Effect of Ps quenching or/and inhibition due to interaction with chemical environment is expected to be maximal in this compositional domain.…”