低温生长砷化镓的超快光抽运-太赫兹探测光谱

发布时间：2018-01-18 08:12

本文关键词：低温生长砷化镓的超快光抽运-太赫兹探测光谱　出处：《物理学报》2017年08期 　论文类型：期刊论文

【摘要】：本文采用光抽运-太赫兹探测技术系统研究了低温生长砷化镓(LT-GaAs)中光生载流子的超快动力学过程.光激发LT-GaAs薄层电导率峰值随抽运光强增加而增加,最后达到饱和,其饱和功率为54μJ/cm~2.当载流子浓度增大时,电子间的库仑相互作用将部分屏蔽缺陷对电子的俘获概率,从而导致LT-GaAs的快速载流子俘获时间随抽运光强增加而变长.光激发薄层电导率的色散关系可以用Cole-Cole Drude模型很好地拟合,结果表明LT-GaAs内部载流子的散射时间随抽运光强增加和延迟时间(产生光和抽运光)变长而增加,主要来源于电子-电子散射以及电子-杂质缺陷散射共同贡献,其中电子-杂质缺陷散射的强度与光激发薄层载流子浓度密切相关,并可由散射时间分布函数α来描述.通过对光激发载流子动力学、光激发薄层电导率以及迁移率变化的研究,我们提出适当增加缺陷浓度,可以进一步降低载流子迁移率和寿命,为研制和设计优良的THz发射器提供了实验依据.
[Abstract]:The low temperature growth of Gallium arsenide (LT-GaAs) has been studied by optically pumped terahertz (THz) technique. Ultrafast kinetic process of mesophotogenic carriers. The peak conductivity of photoexcited LT-GaAs thin layer increases with the increase of pump light intensity. Finally, the saturation power is 54 渭 J / cm ~ (-2). When the carrier concentration increases, the Coulomb interaction between electrons will lead to the capture probability of partially shielded defects. As a result, the fast carrier trapping time of LT-GaAs increases with the increase of pump intensity. The dispersion relation of conductivity of photoexcited thin layer can be obtained by Cole-Cole. The Drude model fits well. The results show that the carrier scattering time increases with the increase of the pump intensity and the delay time (producing light and pumping light). The main contributions are electron-electron scattering and electron-impurity defect scattering. The intensity of electron-impurity defect scattering is closely related to the carrier concentration of photoexcited thin layer. It can be described by the scattering time distribution function 伪. By studying the photoexcited carrier dynamics, the conductivity of photoexcited thin layer and the change of mobility, we propose to increase the defect concentration appropriately. The mobility and lifetime of carriers can be further reduced, which provides experimental basis for the development and design of excellent THz emitters.
【作者单位】：上海大学物理系;中国科学院上海微系统与信息技术研究所中国科学院太赫兹固态技术重点实验室;
【基金】：国家自然科学基金(批准号:11674213,11604202,61405233) 国家重大科学仪器设备开发专项(批准号:2011YQ150021) 上海市教委重点课题(批准号:14ZZ101)资助的课题~~
【分类号】：TN304.23
【正文快照】： 压.LT-GaAs是最常用的光电导材料.通过低温条1引言件下(约300 K)生长的GaAs,会引入大量的缺陷,, __ 、从而形成载流子的俘获陷阱或复合中心.LT-GaAs低温生长砷化镓(LT'GaAs)具有尚载流子S中主要存在两种载流子俘获机制:在缺陷俘获模型移率和快载流子俘获速率以及高暗电阻率

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