1. Investigation of ultrafast dynamics of CdTe quantum dots by femtosecond uorescence up-conversion spectroscopy.
- Author
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Yao Guan-Xin, Lü Liang-Hong, Gui Mei-Fang, Zheng Xian-Feng, Ji Xue-Han, Zhang Hong, and Cui Zhi-Feng
- Subjects
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FLUORESCENCE spectroscopy , *CADMIUM telluride , *QUANTUM dots , *NANOSTRUCTURED materials , *BAND gaps , *HOLES (Electron deficiencies) - Abstract
The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy. Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ~ 1.6 ps with exciting at 400 nm, depending on the state of the photo-excited hole. The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots. In addition, Auger relaxation of trapped carriers is observed to occur with a time constant of ~ 5 ps. A schematic model of photodynamics is established based on the results of the spectroscopy studies. Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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