Spectroscopy studies of structural phase transitions of chalcogenide glass thin films (Ge2S3)x(As2S3)1−x at coordination number 2.67

We have investigated Fourier transform infrared (FTIR) spectra, Raman spectra and ultraviolet and visible absorption spectra of the (Ge2S3)x(As2S3)1−x chalcogenide glass thin films with 0.1≤x≤0.9 and the average coordination number Z between 2.52 and 2.76. The relation of the structural and optical properties to the average coordination number is demonstrated by varying the composition parameter x of the glass. All measured quantities energy gap, sound velocity, IR and Raman peak intensities, position and the intensity of the boson peak showed the extreme values at Z=2.67, indicating that structural phase transition occur at this coordination number.