Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

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Photoluminescence excitation and transmission spectra of Si nanocrystals of different diameters embedded
in a SiO2 matrix have been investigated in the broad visible-vacuum ultraviolet spectral range using
synchrotron radiation. The dependence of the photoluminescence excitation spectra on the nanocrystals size
was experimentally established. It is shown that the photoluminescence excitation and absorption spectra are
significantly blueshifted with decreasing Si nanocrystal size. A detailed comparison of photoluminescence
excitation and absorption spectra with data from theoretical modeling has been done. It is demonstrated that
the experimentally determined blueshift of the photoluminescence excitation and absorption spectra is larger
than the theoretical predictions. The influence of point defects in the SiO2 matrix on the optical and luminescence
properties of the embedded Si nanocrystals is discussed. Moreover, it is demonstrated that no energy transfer
takes place between the SiO2 and Si nanocrystals when the excitation energy is higher than the band-to-band
transition energy in SiO2.
Original languageEnglish
JournalPhysical Review B
Publication statusPublished - 28 Jan 2011

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