Spectroscopic Study on Inverse Auger Effect of Semiconductor Quantum Dots

半导体量子点反俄歇效应的光谱研究

基本信息

批准号：
18550024
负责人：
TAMAI Naoto
金额：
$ 2.64万
依托单位：
Kwansei Gakuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18550024/
关键词：
Inverse Auger Effect Semiconductor Quantum Dots Single-Photon Timing Auger Effect Transient Absorption Spectroscopy Single Particle Spectroscopy オージェ効果発光寿命

项目摘要

Various sized CdTe QDs were synthesized in organic and water solvents, and the precursors were removed by several methods. Steady-state luminescence spectra were examined as a function of excitation wavelength, and the spectral shape of QDs was found to be independent of the wavelength, suggesting the free from an impurity. The second (400nm) and third (266nm) harmonics of femtosecond Ti:sapphire laser were used as excitation pulse to measure the luminescence decay and analyze inverse Auger effect.By using various sized CdTe QDs, we found that inverse Auger effect was observed when ω/Eg is larger than 2.5, in which the lifetime becomes shorter and multicarriers are formed in single CdTe QDs. For 5.4nm sized CdTe QDs (Eg=1.73 eV), the quantum efficiency of inverse Auger effect was 190%. In addition, the effective mass of the electron and hole may play an important role on the threshold energy of 2.5Eg for inverse Auger effect of CdTe QDs. Excitation intensity dependence of transient absorption dynamics was also examined to reveal Auger effect of CdTe QDs that is due to the interaction of muliticarriers generated by inverse Auger effect. The Auger effects of CdTe QDs and nanowires can be analyzed by the time-dependent recombination rate by Global analysis and the Auger recombination rate of nanowires was found to be larger than that of QDs. Furthermore, the excitation intensity dependence in single particle spectroscopy revealed that the Auger ionization plays an dominant role for the blinking dynamics of CdTe QDs.

在有机和水溶剂中合成了各种尺寸的 CdTe QD，并通过多种方法去除了前驱体，检查了稳态发光光谱与激发波长的关系，发现 QD 的光谱形状与波长无关。表明不含杂质的飞秒钛宝石激光器的二次谐波（400nm）和三次谐波（266nm）被用作激发脉冲来测量。通过使用不同尺寸的CdTe量子点，我们发现当ω/Eg大于2.5时，观察到逆俄歇效应，其中寿命变短并且在单个CdTe量子点中形成多载流子（对于5.4）。纳米尺寸的CdTe量子点（Eg=1.73 eV），反俄歇效应的量子效率为190%。电子和空穴的质量可能对 CdTe QD 的反俄歇效应的 2.5Eg 阈值能量发挥重要作用，还研究了吸收瞬态动力学的激发强度依赖性，以揭示 CdTe QD 的俄歇效应是由于相互作用造成的。由反俄歇效应产生的多载流子 CdTe QD 和纳米线的俄歇效应可以通过全局分析的时间相关复合率和俄歇复合率进行分析。此外，单粒子光谱中的激发强度依赖性表明，俄歇电离对 CdTe 量子点的闪烁动力学起着主导作用。