Effect of the surrounding oxide on the photoabsorption spectra of Si nanocrystals
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© 2009 American Physical Society (APS). This is the accepted version of the following article: Koponen, Laura & Tunturivuori, Lasse O. & Puska, Martti J. & Nieminen, Risto M. 2009. Effect of the surrounding oxide on the photoabsorption spectra of Si nanocrystals. Physical Review B. Volume 79, Issue 23. 235332/1-6. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.79.235332, which has been published in final form at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.79.235332.
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2009
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Language
en
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235332/1-6
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Physical Review B, Volume 79, Issue 23
Abstract
A systematic study of the optical absorption of small silicon nanocrystals (Si-NCs) embedded in silicon dioxide is performed using real-time time-dependent density-functional theory. The modeled Si-NCs contain up to 47 Si atoms with the surrounding oxide being described by a shell of SiO2. The oxide-embedded Si-NCs exhibit absorption spectra that differ significantly from the spectra of the hydrogen-passivated Si-NCs. In particular, the minimum absorption energy is found to decrease when the Si-NCs are exposed to dioxide coating. Unexpectedly, the absorption energy of the oxide-embedded Si-NCs remains approximately constant for core sizes down to 17 atoms, whereas the absorption energy of the hydrogen-passivated Si-NCs increases with decreasing crystal size. This trend suggests a different mechanism for producing the lowest-energy excitations in these two cases.Description
Keywords
Si nanocrystals, photoluminiscence, time-dependent density functional theory
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Citation
Koponen, Laura & Tunturivuori, Lasse O. & Puska, Martti J. & Nieminen, Risto M. 2009. Effect of the surrounding oxide on the photoabsorption spectra of Si nanocrystals. Physical Review B. Volume 79, Issue 23. 235332/1-6. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.79.235332.