SUBPICOSECOND ELECTRIC-FIELD DYNAMICS IN LOW-TEMPERATURE-GROWN GAAS OBSERVED BY REFLECTIVE ELECTROOPTIC SAMPLING
SUBPICOSECOND ELECTRIC-FIELD DYNAMICS IN LOW-TEMPERATURE-GROWN GAAS OBSERVED BY REFLECTIVE ELECTROOPTIC SAMPLING
复制标题
DOI：
10.1016/0921-5107(93)90225-c
复制
发表时间：
1993-12-20
期刊：
影响因子：
--
通讯作者：
KURZ, H
中科院分区：
文献类型：
--
作者：
DEKORSY, T;ZHOU, XQ;KURZ, H
本文首次利用飞秒时间分辨率的反射电光采样（REOS）研究了生长和生长后退火低温砷化镓中的亚皮秒电场和相干LO声子动力学。这种技术可以直接观察到在脉冲光激发fret载流子后的内置表面场的筛选，以及由于这种高电阻率材料中电子和空穴的不同迁移率（光Dember效应）而形成的电场。在捕获移动载波后，信号的衰减给出了在捕获状态下载波寿命的精确测量。观察到的退火和生长的低密度砷化镓的差异与过量砷的微观形式和点缺陷的密度有关。相干LO声子的产生允许在生长和退火的LT GaAS中确定LO声子的频率和寿命。在生长的LT GaAS中，除了LO声子的红移外，我们还观察到一个低于LO频率的额外的本地模式，这为结构缺陷提供了证据。
For the first time we investigate the subpicosecond electric field and coherent LO phonon dynamics in as-grown and post-growth th annealed low-temperature (LT) GaAs by reflective electro-optic sampling (REOS) with femtosecond time-resolution. This technique allows a direct observation of the screening of built-in surface fields after pulsed optical excitation of fret carriers and the built-up of an electric field due to the different mobilities of electrons and holes (photo Dember effect) in this high resistivity material. After trapping of mobile carriers the decay of the signal gives an accurate measure of the carrier lifetime in trapped states. The observed differences in annealed and as-grown LT GaAs are related to the microscopic form of excess arsenic and the density of point defects. The generation of coherent LO phonons allows the determination of the LO phonon frequency and lifetime in as-grown and annealed LT GaAS. Besides a red-shift of the LO phonon in as-grown LT GaAS we observe an additional local-mode below the LO frequency, which gives evidence for structural defects.