Raman scattering in amorphous films of In_1-xSe_x alloys

Raman scattering (RS) in amorphous films of In_1-xSe_x with 0.67±x≥0.38 has been studied in backscattering geometry with the use of a microscope. Recorded RS spectra are revealing a mixed vibrational density-of-states and molecular character. The spectra spread from the Rayleigh line up to 200-250 cm^-1. The bands superimposed on the continua are related to zone center modes of the relevant crystal counterpart, Se-Se or In-In vibrations. The RS spectra suggest the structure of the In_1-xSe_x alloys to be the continuous random network built up of In centered tetrahedral clusters with In and Se atoms at the corners. The structure of the Se-rich alloys is similar to 4-2 networks with dominant InSe_4/2 clusters and two-fold coordination of Se bridging atoms. That of the In-rich alloys is expected to resemble 4-3 network with rather strong involvement of In atoms at corner of the In-centered tetrahedral clusters and Se atoms being linked to three In ones.