Optical properties and structural correlations of GeAsSe chalcogenide glasses

GexAsySe100-x-y (33 <= x <= 39 and 12 <= y <= 16) glasses were prepared, and their structure and optical properties were studied by Raman and UV-Vis-IR spectroscopic techniques. Ge-tetrahedrons [GeSe4] dominated in the structural units, and 'defect' bonds, such as Ge-Ge, Ge-As and As-As bonds, also occurred in the glasses. A structural model for calculation of the optical band gap energy (E,) of Ge-As-Se glasses was proposed, and the calculated values are consistent with experimental results. Increasing germanium and decreasing selenium content can reduce both the mean bond energies and optical band gap energies, enhancing the photo-sensitivity of the glasses.