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Electron-phonon coupling and localization of excitons in single silicon nanocrystals

: Martin, J.; Cichos, F.; Huisken, F.; Borczyskowski, C. von


Nano Letters 8 (2008), Nr.2, S.656-660
ISSN: 1530-6984
ISSN: 1530-6992
Fraunhofer IZM ()
Fraunhofer ENAS ()

We report a detailed photoluminescence (PL) study on single silicon nanocrystals produced by laser pyrolysis. The PL spectra reveal nearly homogeneously broadened zero-phonon lines coupled to Si-O-Si phonon transitions in the SiO2 shell. A systematic investigation of electron-phonon coupling is reported on-the basis of single nanocrystals. The stepwise localization of electron and hole at the Si-SiO2 interface for nanocrystals smaller than d approximate to 2.7 nm is driven by electron-phonon coupling. From the localization energies the effective Bohr radii of the (localized) electron and hole are estimated to be in the range of 1-2 bond lengths of Si-O and Si-Si.