Ma Hong et al 2008 Chinese Phys. B 17 1280 doi:10.1088/1674-1056/17/4/022
Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots
Ma Hong1, Ma Guo-Hong1, Wang Wen-Jun2, Gao Xue-Xi2 and Ma Hong-Liang3
Show affiliationsSize-dependence of optical properties and energy relaxation in CdSe/ZnS quantum dots (QDs) were investigated by two-colour femtosecond (fs) pump-probe (400/800 nm) and picosecond time-resolved photoluminescence (ps TRPL) experiments. Pump-probe measurement results show that there are two components for the excited carriers relaxation, the fast one with a time constant of several ps arises from the Auger-type recombination, which shows almost particle size-independence. The slow relaxation component with a time constant of several decades of ns can be clearly determined with ps TRPL spectroscopy in which the slow relaxation process shows strong particle size-dependence. The decay time constants increase from 21 to 34 ns with the decrease of particle size from 3.2 to 2.1 nm. The room-temperature decay lifetime is due to the thermal mixing of bright and dark excitons, and the size-dependence of slow relaxation process can be explained very well in terms of simple three-level model.
- PACS
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71.35.-y Excitons and related phenomena
79.20.Fv Electron impact: Auger emission
- Subjects
- Dates
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Issue 4 (April 2008)
Received 22 June 2007, in final form 22 October 2007
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Size-dependent optical properties and carriers dynamics in CdSe/ZnS quantum dots
Ma Hong et al 2008 Chinese Phys. B 17 1280
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