Impact of Self-Trapped Excitons on Blue Photoluminescence in TiO2 Nanorods on Chemically Etched Si Pyramids

Temperature-dependent photoluminescence (PL) of titanium oxide (TiO2) shows an evolution of blue emission when exposed to 50 keV Ar+ ions. The origin of observed PL has been examined by X-ray absorption near-edge spectroscopy (XANES) at Ti-K,L and O-K edges, revealing the reduction of ligand field s...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2017-06, Vol.121 (21), p.11448-11454
Main Authors: Saini, C. P, Barman, A, Banerjee, D, Grynko, O, Prucnal, S, Gupta, M, Phase, D. M, Sinha, A. K, Kanjilal, D, Skorupa, W, Kanjilal, A
Format: Article
Language:English
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Summary:Temperature-dependent photoluminescence (PL) of titanium oxide (TiO2) shows an evolution of blue emission when exposed to 50 keV Ar+ ions. The origin of observed PL has been examined by X-ray absorption near-edge spectroscopy (XANES) at Ti-K,L and O-K edges, revealing the reduction of ligand field splitting owing to the formation of oxygen vacancies (OVs) by destroying TiO6 octahedral symmetry. Detailed PL and XANES analyses suggest that the fluence (ions/cm2) dependent increase in OVs not only boosts the conduction electrons but also increases the density of holes in localized self-trapped exciton (STE) states near the valence band. Based on these observations, we propose a model in which doped conduction electrons are recombining radiatively with the holes in STE states for blue light emission.
ISSN:1932-7447
1932-7455
DOI:10.1021/acs.jpcc.7b02218