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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不同尺寸的CdTe量子点，并通过几种方法去除了前驱体。研究了稳态发光光谱作为激发波长的函数，发现量子点的光谱形状与波长无关，表明量子点中没有杂质。用飞秒钛宝石激光的二次(400 Nm)和三次(266 Nm)倍频作为激发脉冲，测量了发光衰减并分析了反向俄歇效应，通过对不同尺寸的ω/Eg大于2.5时观察到了反向俄歇效应，单点寿命变短，形成了多个载流子。对于尺寸为5.4 nm的CdTe量子点(Eg=1.73 eV)，反俄歇效应的量子效率为190%。此外，电子和空穴的有效质量可能对2.5Eg的阈值能量起着重要的作用。研究了激发强度对瞬时吸收动力学的影响，揭示了由逆俄歇效应产生的多载流子相互作用引起的量子点的俄歇效应。Global分析可以用随时间变化的复合速率来分析量子点和纳米线的俄歇效应，发现纳米线的俄歇复合速率大于量子点的俄歇复合速率。此外，单粒子光谱的激发强度依赖关系表明，俄歇电离对CdTe量子点的闪烁动力学起主导作用。