中国物理B ›› 2008, Vol. 17 ›› Issue (4): 1280-1285.doi: 10.1088/1674-1056/17/4/022
马红1, 马国宏1, 马洪良2, 王文军3, 高学喜3
Ma Hong(马红)a), Ma Guo-Hong(马国宏)a)†, Wang Wen-Jun(王文军)b), Gao Xue-Xi(高学喜)b), and Ma Hong-Liang(马洪良)c)
摘要: Size-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.
中图分类号: (Excitons and related phenomena)