Effects of annealing atmosphere and substrate on the photoluminescence and Raman scattering from Si nanocrystals in a SiO2 matrix

Thin films of SiOx have been prepared on quartz or c-Si substrates by thermal evaporation of SiO in vacuum and post-annealed at 1373 Kin an argon or hydrogen atmosphere. High-resolution electron microscopy has shown the existence of silicon nanocrystals in the annealed films, and this result has been confirmed by Raman scattering. Photoluminescence has been observed from annealed films and attributed to radiative recombination in Si nanocrystals. Its intensity is appreciably higher upon annealing in Ar than in H-2. It is shown that substrates strongly affect the Raman scattering from Si nanocrystals in nc-Si-SiO2 thin films with low filling factors. (C) 2003 Kluwer Academic Publishers.