Raman and x-ray diffraction data analysis of Ge2Sb2Te5 films using gaussian approximation considering the temperature population factor

The structure particulars of amorphous Ge2Sb2Te5 thermally evaporated on glass substrates, as well as films annealed at temperatures of 500 and 700 K have been studied by the considering of experimentally established facts obtained from X-ray analysis and Raman spectroscopy measurements. The Debye-Scherrer and Williams-Hall methods were applied to the X-ray diffraction data for estimate the size of crystallites, interatomic distances, dislocation density and structure distortion degree. The features of heat treatment effect on numerical values of the above quantities at a given temperatures have been established. The analysis of the spectral distribution of Raman scattering was measured at light frequencies between 40 divided by 300 cm-1 . The rather extended nature of the identified bands suggests the presence of several vibrational modes, leading to the appearance of individual spectral bands. To determine the vibrational modes, a reduced intensity was constructed from the experimental Raman spectrum data and the Gaussian approximation was applied to the latter. Having a mind the results of published works, the vibration modes existing in the samples obtained immediately after the process of layer application were determined, as well as the chemical nature and structure elements corresponding to these modes forming the amorphous matrix. The vibration modes in crystallized layers after heat treatment at the given temperatures were determined, as well as the chemical bonds and structural units forming their local structure.