量子点表面空穴俘获动力学的新型探测：电子自旋调控法

发布时间：2018-03-22 21:32

本文选题：空穴俘获　切入点：超快瞬态吸收谱　出处：《华东师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：纳米晶体的表面态对材料的光电性质有重要的影响,其中一个重要过程就是表面对载流子的俘获作用。载流子动力学通常采用时间分辨光致荧光谱和瞬态吸收谱来间接测得,这些方法是基于载流子带边激发态的退布居过程。由于载流子俘获过程以及辐射和非辐射复合过程均对带边激发态退布居过程有贡献,因此只能在低激发功率下结合多种探测技术才能解析出空穴俘获过程。本文提出了一种直接探测纳米晶体表面空穴俘获过程的新技术：泵浦-自旋极化-探测技术。泵浦光产生电子-空穴对,空穴表面俘获过程将被激发的电子-空穴对空间上分离,使核上带有负电,因此增强了自旋极化脉冲产生的电子自旋信号。自旋增强瞬态信号与泵浦-自旋极化光延迟时间的函数关系反映了一个快俘获过程和一个慢俘获过程,俘获时间分别为～10ps和～100ps。这种新技术在较高激发功率下也可获得空穴俘获的动力学过程。空穴俘获动力学的功率依赖体现了空穴表面俘获饱和过程和俘获点的相对数目,表明空穴表面俘获点有三种纳米颗粒分布：一种仅对应快俘获过程,另一种仅对应慢俘获过程,而第三种则同时包括快慢两个俘获过程。
[Abstract]:Has an important influence on the photoelectric properties of material surface state of nano crystal, one of the important role of the capture process is on the surface of the carrier. The carrier dynamics usually by time-resolved photoluminescence spectra and transient absorption spectrum is measured indirectly, these methods are back cloth carrier with the excited state based on the ranking process. The carrier capture process and radiative and non radiative recombination processes are excited to bring back side population process contribute, so can only be combined with a variety of detection technology to resolve the hole capture process at low excitation power. This paper presents a new technique for direct detection of nano crystal surface hole trapping process: Pump spin polarization detection technology. The pump generated electron hole pairs, the hole surface trapping process will be excited by the electron hole pairs are spatially separated, the nucleus of the negatively charged, so the enhanced spin Electron spin polarization pulse signal generated. Spin enhanced transient signal and pump - spin polarized light delay function of time reflects a fast capture process and a slow capture process, capture time respectively to dynamic process of 10ps and to the new technology 100ps. at high excitation power can also be obtained by hole trapping power. The dependence of hole trapping dynamics reflects the relative number of hole surface to capture and capture the saturation process, shows that there are three kinds of hole surface trapping point distribution of nanoparticles: a corresponding only fast capture process, another only corresponding slow capture process, while the third one at the same time, including the speed of the two capture process.

【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O471.1

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