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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 L2,3 edge

Šiller, L.; Krishnamurthy, S.; Kjeldgaard, L.; Horrocks, B. R; Chao, Y.; 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 L2,3 edge. Journal of Physics: Condensed Matter, 21(9), article no. 095005.

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URL: http://iopscience.iop.org/0953-8984/21/9/095005/
DOI (Digital Object Identifier) Link: https://doi.org/10.1088/0953-8984/21/9/095005
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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: Journal Item
Copyright Holders: 2009 IOP Publishing Ltd
ISSN: 0953-8984
Extra Information: 9 pp.
Keywords: Si nanocrystals; soft x-ray photoemission; x-ray emission; NEXAFS; optical luminescence; exciton; solar cells
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Engineering and Innovation
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 36856
Depositing User: Satheesh Krishnamurthy
Date Deposited: 13 Mar 2013 14:03
Last Modified: 21 Mar 2017 15:30
URI: http://oro.open.ac.uk/id/eprint/36856
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