Raman scattering probe of anharmonic effects in NiSi

We report a systematic temperature-dependent Raman scattering study of NiSi thin films. In agreement with the basic anharmonic theory, the strong Raman peak from NiSi at about 214 cm(-1) shows phonon softening and broadening with an increase in the sample temperature. Comparative study of the temperature dependence of this first-order Raman peak from NiSi powder and the film show that NiSi layers of thickness 15-90 nm are under tensile thermal stress. The results also show that the total phonon shift observed in the temperature range 80-500 K is independent of the silicide film thickness. We have also shown that Raman spectroscopy is a faster and more sensitive technique than x-ray diffraction for phase identification in NiSi nanolayers, hence Raman scattering can be used as a valuable tool for in situ growth and process monitoring of nickel silicides. Copyright (C) 2004 John Wiley Sons, Ltd.