CdSeS量子点的超快光物理特性研究  

Ultrafast Optical Physic Properties of CdSeS Quantum Dots

作　　者：安美英 张郑兵[1] 金钻明[1] 林贤[1] 马国宏[1] 

机构地区：[1]上海大学理学院物理系,上海200444

出　　处：《光学学报》2013年第10期307-311,共5页Acta Optica Sinica

基　　金：国家自然科学基金(11174195)

摘　　要：利用飞秒抽运-探测透射技术,研究了室温下CdSeS半导体量子点激发态载流子的弛豫过程与抽运光能量密度和光子能量的关系。实验结果表明,CdSeS量子点激发态载流子的弛豫有3个过程:1)约为10ps的一个快速弛豫过程,此过程随着抽运光能量密度的不断增加而逐渐变慢,与光子能量没有明显的依赖关系,认为此过程是由载流子和光学声子的散射引起的;2)约为100ps的一个弛豫过程,此过程与抽运光能量密度及光子能量都没有明显的依赖关系,认为此过程是光激发载流子被缺陷态捕获而形成的限域载流子的弛豫过程;3)一个纳秒量级的带-带跃迁的弛豫过程。零延迟时间下的透射变化量随着抽运光能量密度的增大而增大,当抽运光能量密度增大到一定程度时,零延迟下的透射变化量逐渐趋于饱和。The transient carrier dynamics of CdSeS quantum dots is investigated by time-resolved femtosecond pump- probe transmission spectroscopy method at different photon energies and pump energy densities. The experimental results show that the relaxation of excited state of CdSeS quantum dots have three processes. The first one is a rapid relaxation process whose time scale is about 10 ps. The rapid process time constant increases when the pump energy density increases and is independent of the photon energy. We hold the opinion that the rapid process is caused by the carrier and the optical phonon scattering. The second relaxation process whose time constant is about 100 ps. The carrier relaxation time is independent of the pump energy density and photon energy. The component is associated with recombination via trap states. Then a slow decay process due to single exciton relaxation with a lifetime as long as nanoseconds can be observed. This process is attributed to inter-band relaxation. The transmission change increases with the increase of pump energy density at zero delay time. When the pump energy density increases to a certain extent, the transmission change under the zero delay gradually tend to be saturated.

关 键 词：超快光学 载流子动力学 飞秒抽运-探测技术 CdSeS量子点 

分 类 号：O472.8[理学—半导体物理]