Role of S/Se ratio in chemical bonding of As-S-Se glasses investigated by Raman, x-ray photoelectron, and extended x-ray absorption fine structure spectroscopies

Abstract

Chalcogenide glasses have attracted considerable attention and found various applications due to their infrared transparency and other optical properties. The As-S-Se chalcogenide glass, with its large glass-formation domain and favorable nonlinear property, is a promising candidate system for tailoring important optical properties through modification of glass composition. In this context, a systematic study on ternary As-S-Se glass, chalcogen-rich versus well-studied stochiometric compositions, has been carried out using three different techniques: Raman spectroscopy, x-ray photoelectron spectroscopy, and extended x-ray absorption fine structure spectroscopy. These complementary techniques lead to a consistent understanding of the role of S/Se ratio in chalcogen-rich As-S-Se glasses, as compared to stochiometric composition, and to provide insight into the structural units (such as the mixed pyramidal units) and evidence for the existence of homopolar bonds (such as Se-Se, S-S, and Se-S), which are the possible structural origin of the high nonlinearity in these glasses