Raman spectra of In0.30Se0.70 amorphous films

Amorphous films of In0.30Se0.70 alloy thermally evaporated from one source onto borosilicate glass substrates were studied by Raman scattering at 300 It and 10 K. The Raman scattering spectra excited with 488 and 457.9 nm 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 250 cm(-1) and rather featureless background due to second-order processes beyond it. The room temperature spectra show a strong feature at about 143 cm(-1) that is lacking in the spectra taken at 10 K and, instead, a weak band at about 125 cm(-1) is observed. The Raman scattering spectra recorded at both temperatures appear to be dependent on the excitation line within the 40-50 cm(-1) range. The feature at about 143 cm(-1) is attributed to Se chain modes while a weaker band at about 125 cm(-1) observed at low temperature is due to See ring molecules. The dynamics of the In0.30Se0.70 films is treated in terms of a continuous random network composed of rather strongly interconnected InSe4 tetrahedral clusters.