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Lookup NU author(s): Rebecca Rostron, Dr Ben Horrocks, Dr Gareth Roberts
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Orange luminescence attributable to a core of silicon atoms in alkyl-capped crystalline quantum dots excited at lambda(a) = 355 and 405 nm is investigated as a function of applied intensity and time. The intensity of luminescence displays a linear power dependence on the intensity of the applied field, from which an exponent n = 0.94 +/- 0.02 commensurate with single-photon absorption is derived. The dependence of luminescence on time is observed to be strongly nonexponential and is optimally accounted for by a probability density function which describes a continuous distribution of two decay times: the behavior is characteristic of a pair of elementary steps connected with light emission within a distribution of local environments, or a single rate process supported by two environments. Nonlinear least-squares fits to the time dependent luminescence formulated on this basis with a Gaussian, Lorentzian, or log-normal distribution of rates return most probable lifetimes (T) over bar (1) = 21 + 1 mu s and (T) over bar (2) = 3.7 + 0.8 mu s. The widths of the distributions vary between sigma(1) = 0.01-0.03 mu s(-1) and sigma(2) = 0.14- 1.1 mu s(-1) associated with 1/(T) over bar (1) and 1/(T) over bar (2), respectively. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3120787]
Author(s): Rostron RJ, Horrocks BR, Roberts G
Publication type: Article
Publication status: Published
Journal: Journal of Applied Physics
Year: 2009
Volume: 105
Issue: 9
Pages: 094302
ISSN (print): 0021-8979
ISSN (electronic): 1520-8850
Publisher: American Institute of Physics
URL: http://dx.doi.org/10.1063/1.3120787
DOI: 10.1063/1.3120787
Notes: Article no. 094302 8 pages
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