Investigation of ultrafast dynamics of CdTe quantum dots by femtosecond fluorescence up-conversion s

• 作 者: 姚关心 吕良宏 桂美芳 张先燚 郑贤锋 季学韩 张宏 崔执凤
• 机 构: Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Institute of Atomic and Mol
• 出 处: Chinese Physics B
• 发表日期: 2012年10期
• 关键词: CdTe relaxation trapped excited forbidden shallow exciting decay elsewhere schem

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.

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 gaps are confirmed for CdTe quantum dots.In addition, Auger relaxation of trapped carriers is observed 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.