6533b82cfe1ef96bd128f59c

RESEARCH PRODUCT

Si nanocrystals embedded in $SiO_2$: Optical studies in the vacuum ultraviolet range

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Photoluminescence excitation and transmission spectra of Si nanocrystals of different diameters embeddedin a SiO2 matrix have been investigated in the broad visible-vacuum ultraviolet spectral range usingsynchrotron radiation. The dependence of the photoluminescence excitation spectra on the nanocrystals sizewas experimentally established. It is shown that the photoluminescence excitation and absorption spectra aresignificantly blueshifted with decreasing Si nanocrystal size. A detailed comparison of photoluminescenceexcitation and absorption spectra with data from theoretical modeling has been done. It is demonstrated thatthe experimentally determined blueshift of the photoluminescence excitation and absorption spectra is largerthan the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescenceproperties of the embedded Si nanocrystals is discussed. Moreover, it is demonstrated that no energy transfertakes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-bandtransition energy in SiO2.