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

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 

机构地区：[1]Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences [2]Institute of Atomic and Molecular Physics,Anhui Normal University [3]College of Chemistry and Materials Science,Anhui Normal University [4]Van't Hoff Institute for Molecular Sciences,University of Amsterdam,Science Park 904,1090 GD Amsterdam,The Netherlands

出　　处：《Chinese Physics B》2012年第10期466-471,共6页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant Nos. 11074003 and 20973001);the Key Program of Educational Commission of Anhui Province of China (Grant No. KJ2010A132)

摘　　要：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 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.

关 键 词：CdTe quantum dots femtosecond fluorescence up-conversion spectroscopy ultrafast dynamics NANOMATERIAL 

分 类 号：O471.1[理学—半导体物理] TQ171.112[理学—物理]