Nature of the power-dependent ultrafast relaxation process of photoexcited charge carriers in II-VI semiconductor quantum dots: Effects of particle size, surface, and electronic structure
Nature of the power-dependent ultrafast relaxation process of photoexcited charge carriers in II-VI semiconductor quantum dots: Effects of particle size, surface, and electronic structure
复制标题
DOI：
10.1063/1.475593
复制
发表时间：
1998-06
影响因子：
4.4
通讯作者：
T. Roberti;N. Cherepy;J. Zhang
中科院分区：
文献类型：
--
作者：
T. Roberti;N. Cherepy;J. Zhang
利用飞秒激光光谱研究了II-VI族半导体量子点中光激发载流子的弛豫动力学。的动力学是通过激发的量子点与高功率390 nm脉冲的150 fs的持续时间，和探测的光激发的物种通过监测在790 nm处的吸收作为时间的函数的变化。具有不同表面、尺寸、电子结构和溶剂的颗粒都显示出随功率增长的快速1.5-4皮秒衰减分量，17 ps（CdSe）或50 ps（CdS和Cd0.5Zn0.5S）衰减分量，以及一些持续超过600 ps的瞬态吸收。玻璃中的CdSe量子点的功率依赖分量具有1.5ps的衰减时间常数，而对于液体分散的CdS和Cd 0.5Zn 0.5S量子点，其具有2- 4ps的衰减时间常数。时间常数的这种变化是由于其功率依赖性，时间常数随着功率的增加而减小。它还表明，P…
The power-dependent relaxation dynamics of photoexcited charge carriers in a number of II-VI semiconductor quantum dots have been studied using femtosecond laser spectroscopy. The dynamics are obtained via excitation of the quantum dots with high power 390 nm pulses of 150 fs duration, and probing of the photoexcited species by monitoring the change in absorption at 790 nm as a function of time. Particles with vastly differing surfaces, sizes, electronic structures, and solvents all show a fast 1.5–4 picosecond decay component which grows in with power, a 17 ps (CdSe) or 50 ps (CdS and Cd0.5Zn0.5S) decay component, and some transient absorption persisting beyond 600 ps. The power-dependent component for CdSe quantum dots in glass has a 1.5 ps decay time constant, while for the liquid dispersed CdS and Cd0.5Zn0.5S quantum dots it has 2–4 ps decay time constants. This variation in the time constant is due to its power dependence, the time constant decreases with increasing power. It is also shown that the p...