Raman Spectra of In$\text{}_{0.30}$Se$\text{}_{0.70}$ Amorphous Films

Amorphous films of In$\text{}_{0.30}$Se$\text{}_{0.70}$ alloy thermally evaporated from one source onto borosilicate glass substrates were studied by Raman scattering at 300K and 10K. The Raman scattering spectra excited with 488 and 457.9nm laser lines were recorded in a quasi-rectangular geometry with the use of a single channel spectrometer. All the Raman scattering spectra reveal a continuum spreading from the Rayleigh line up to about 250cm$\text{}^{-1}$ and rather featureless background due to second-order processes beyond it. The room temperature spectra show a strong feature at about 143cm$\text{}^{-1}$ that is lacking in the spectra taken at 10K and, instead, a weak band at about 125cm$\text{}^{-1}$ is observed. The Raman scattering spectra recorded at both temperatures appear to be dependent on the excitation line within the 40-50cm$\text{}^{-1}$ range. The feature at about 143cm$\text{}^{-1}$ is attributed to Se chain modes while a weaker band at about 125cm$\text{}^{-1}$ observed at low temperature is due to Se$\text{}_{8}$ ring molecules. The dynamics of the In$\text{}_{0.30}$ Se$\text{}_{0.70}$ films is treated in terms of a continuous random network composed of rather strongly interconnected InSe$\text{}_{4}$ tetrahedral clusters.