Ge-Ga-S/Se glasses studied with PALS technique in application to chalcogenide photonics

Free-volume entities in Ge-Ga-S and crystallization behaviour in Ge-Ga-Se chalcogenide glasses caused by thermal annealing at 380°C for 10, 15 and 50 h are studied using positron annihilation lifetime spectroscopy. It is shown that the structural free-volume entities in theses glasses can be adequately described by positron modes determined within two-state trapping model. The observed changes in defect-related component in the fit of experimental lifetime spectra for annealed glasses testifies in a favour of structural fragmentation of larger free volume entities into smaller ones. Because of strong deviation in defect-free bulk positron lifetime τ_b from corresponding additive values proper to boundary constituents, the studied Ge-Ga-S/Se glasses cannot be considered as typical representatives of pseudo-binary cut-section.