Photoluminescence and Raman scattering of silicon nanocrystals prepared by silicon ion implantion into SiO2 films

Photoluminescence (PL) and Raman spectra of silicon nanocrystals prepared by Si ion implantion into ${\mathrm{SiO}}_{\mathrm{2}}$ layers on Si substrate have been measured at room temperature. Their dependence on annealing temperature was investigated in detail. The PL peaks observed in the as-implanted sample originate from the defects in ${\mathrm{SiO}}_{\mathrm{2}}$ layers caused by ion implantation. They actually disappear after thermal annealing at 800 °C. The PL peak from silicon nanocrystals was observed when thermal annealing temperatures are higher than 900 °C. The PL peak is redshifted to 1.7 eV and the intensity reaches maximum at the thermal annealing temperature of 1100 °C. The characterized Raman scattering peak of silicon nanocrystals was observed by using a right angle scattering configuration. The Raman signal related to the silicon nanocrystals appears only in the samples annealed at temperature above 900 °C. It further proves the formation of silicon nanocrystals in these samples.