Title
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Configuration-interaction excitonic absorption in small Si/Ge and Ge/Si core/shell nanocrystals
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Author
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Abstract
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The excitonic properties of Si(core)/Ge(shell) and Ge(core)/Si(shell) nanocrystals (NC's) with diameters of similar to 1.9 nm are investigated using a combination density functional ab initio method to obtain the single particle wave functions and a configuration interaction method to compute the exciton fine structure and absorption coefficient. These core/shell structures exhibit type II confinement, which is more pronounced for the Si/Ge NC as a consequence of strain. The absorption coefficients of these NC's exhibit a single dominant peak, which has a much larger oscillator strength than the multipeaks found for pure Si and Ge NC's. The exciton lifetime in Si, Ge, and Ge/Si shows a small i:emperature dependence in the range 10-300 K, whereas in Si/Ge, the exciton lifetime decreases more than an order of magnitude in the same temperature range. |
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Language
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English
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Source (journal)
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The journal of physical chemistry: C : nanomaterials and interfaces. - Washington, D.C., 2007, currens
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Publication
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Washington, D.C.
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2012
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ISSN
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1932-7447
[print]
1932-7455
[online]
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DOI
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10.1021/JP2088516
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Volume/pages
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116
:7
(2012)
, p. 4399-4407
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ISI
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000301156500007
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Full text (Publisher's DOI)
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