Single silicon nanocrystals (Si NCs) and SiO2 nanoparticles (SiO2 NPs) have been studied by confocal laser scanning microscopy with the goal to compare both kinds of NPs and to determine to what extent quantum confinement or surface‐related defect centers are responsible for the strong photoluminescence (PL) of Si NCs. Using special laser polarization techniques, the transition dipole moment (TDM) for the excitation of individual NPs (Si and SiO2) could be shown to be stable and one‐dimensional. The single particle spectra of Si NCs and SiO2 NPs are composed of a zero‐phonon line and one or two phonon bands, which are associated with LO3 phonons in SiO2, and reveal in every detail an amazing similarity. Both systems reflect the same dynamical behavior (blinking, bleaching, and TDM flipping). Spectrally resolved fluorescence decay measurements yield the important result that the direct and phonon‐assisted recombination processes occur on the same nanosecond timescale (∼4 ns). These experimental observations suggest that the PL of the Si NCs observed in this study is governed by defect luminescence.

This content is only available via PDF.
You do not currently have access to this content.