Monitoring structural phase transition of (Ge2S3)x(As2S3)1−x chalcogenide glass with Raman spectroscopy

Chalcogenide glass thin films (Ge2S3)x(As2S3)1−x, with x = 0.3, 0.5, 0.7, and 0.9, were prepared by flash thermal evaporation of glass powders on c-Si substrate. We have investigated their structural properties for different average coordination numbers Z = 2.52, 2.6, 2.68 and 2.78. Structural changes were monitored by Raman scattering with two different excitation lines, λ = 1064 nm and λ = 514.5 nm. Recorded spectra confirmed that structural changes of the samples are connected with the change of average coordination number. Shift between spectra recorded with two different excitation lines is observed. The shift was discussed in terms of structural ordering at the threshold Z and its connection with the band-tail states.