Core and valence exciton formation in x-ray absorption, x-ray emission and x-ray excited optical luminescence from passivated Si nanocrystals at the Si L2,3edge

Šiller, L, Krishnamurthy, S, Kjeldgaard, L, Horrocks, B R, Chao, Yimin, Houlton, A, Chakraborty, A K and Hunt, M R C (2009) Core and valence exciton formation in x-ray absorption, x-ray emission and x-ray excited optical luminescence from passivated Si nanocrystals at the Si L2,3edge. Journal of Physics: Condensed Matter, 21 (9). 095005. ISSN 1361-648X

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Abstract

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 L2,3 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 ~1.56 eV (792 nm)) which we attribute to recombination of valence excitons, providing a lower limit to the nanocrystal band gap.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Depositing User: Rachel Smith
Date Deposited: 21 Mar 2011 12:29
Last Modified: 28 Oct 2019 15:39
URI: https://ueaeprints.uea.ac.uk/id/eprint/26762
DOI: 10.1088/0953-8984/21/9/095005

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