Lookup NU author(s): Professor Lidija Siller,
Dr Ben Horrocks,
Dr Yimin Chao,
Professor Andrew Houlton
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Resonant inelastic x-ray scattering (RIXS), x-ray absorption spectroscopy and x-ray excited optical luminescence (XEOL) have been used to measure element specific filled and empty electronic states over the Si L-2,L-3 edge of passivated Si nanocrystals of narrow size distribution ( diameter 2.2 +/- 0.4 nm). These techniques have been employed to directly measure absorption and luminescence specific to the local Si nanocrystal core. Profound changes occur in the absorption spectrum of the nanocrystals compared with bulk Si, and new features are observed in the nanocrystal RIXS. Clear signatures of core and valence band exciton formation, promoted by the spatial confinement of electrons and holes within the nanocrystals, are observed, together with band narrowing due to quantum confinement. XEOL at 12 K shows an extremely sharp feature at the threshold of orange luminescence (i.e., at similar to 1.56 eV ( 792 nm)) which we attribute to recombination of valence excitons, providing a lower limit to the nanocrystal band gap.
Author(s): Siller L, Krishnamurthy S, Kjeldgaard L, Horrocks BR, Chao Y, Houlton A, Chakraborty AK, Hunt MRC
Publication type: Article
Publication status: Published
Journal: Journal of Physics: Condensed Matter
ISSN (print): 0953-8984
ISSN (electronic): 1361-648X
Publisher: IOP Publishing Ltd.
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