Raman analysis of amorphous silicon ruthenium thin films embedded with nanocrystals.

We report the Raman analysis of both as-deposited and annealed amorphous silicon ruthenium thin films embedded with nanocrystals. In the Raman spectra of as-deposited films, variations of TO peak indicate a short-range disorder of a-Si network with an increase of Ru concentration. The substitutional Ru atoms lower the concentration of Si-Si bonds and suppress the intensity of TO peak, but have less effect on TA, LA and LO peaks. In the Raman spectra of annealed films, characteristic parameters confirm the upgrade of a-Si network at a low annealing temperature and the emergence of both ruthenium silicide and silicon nanocrystals at 700 °C. Although ruthenium silicide nanocrystals present no Raman peaks in the Raman spectra of as-deposited samples, the non-linear variations of intensity ratios I_{LA + LO}/ I_TO and I_TA/ I_TO still suggest their existence, and these nanocrystals are subsequently verified by high-resolution transmission electron microscopy. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]