Raman scattering of Ni and Cr amorphous disilicides

The Raman spectra and reflectivity of r.f. sputtered amorphous semimetallic a-NiSi₂ and a-CrSi₂ thin films are reported. Substantial differences between the two amorphous disilicide Raman spectra are associated with changes in the phonon density-of-states as a result of variations in Si(p)-transition metal (d) interactions. The greater width of the bands in the Cr alloy suggests a less ordered local environment. Neither spectrum indicates distinct a-Si-like bands, demonstrating that significant short range order changes have occured.