Raman study of the amorphous SiNi alloy

Raman measurements were carried out for sputtered amorphous SiNi thin films. Raman scattering in a-Si is not influenced by a low Ni content (≤8.3 at.%) to any significant degree, the position of peaks and their widths are not changed. A shift to lower frequencies and a broadening of the high frequency band transverse optical (TO) (which results in a redistribution of phonon states to lower frequencies) are observed with an increase of the Ni content. These modifications are correlated with the presence of Ni in the coordination sphere of Si, as resulted from the calculated local structure in NiSi alloys on the basis of the diffraction patterns.