Systematic correlation between Raman spectra, photoluminescence intensity, and absorption coefficient of silica layerscontaining Si nanocrystals

The correlation between optical, structural, and light-emitting properties of annealed Si-rich silica samples containing different amounts of Si nanocrystals is studied. The intensity of the 1.6eV emission band weakens when the Raman signal coming from the Si nanocrystals gets stronger. On the contrary, the absorption coefficient follows the increase of the Raman intensity with the Si nanocrystal density. The decrease of the photoluminescence is accompanied with the increase of tensile stress, which is suggested by the Raman spectra. Possible explanations of the observed dependencies are discussed.