ABSTRACT Optical grating technique, where optical gratings are generated via light inference, has been widely used to measure charge carrier and phonon transport in semiconductors. In this paper, compared are three types of transient optical grating techniques: transient grating diffraction, transient grating heterodyne, and grating imaging, by utilizing them to measure carrier diffusion coefficient in a GaAs/AlAs superlattice. Theoretical models are constructed for each technique to extract the carrier diffusion coefficient, and the results from all three techniques are consistent. Our main findings are: (1) the transient transmission change ∆T/T0 obtained from transient grating heterodyne and grating imaging techniques are identical, even these two techniques originate from different detection principles; and (2) by adopting detection of transmission change (heterodyne amplification) instead of pure diffraction, the grating imaging technique (transient grating heterodyne) has overwhelming advantage in signal intensity than the transient grating diffraction, with a signal intensity ratio of 315:1 (157:1).

中文翻译：

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光栅成像与瞬态光栅技术在半导体载流子扩散测量中的比较

摘要 光栅技术通过光推断产生光栅，已被广泛用于测量半导体中的电荷载流子和声子传输。本文比较了三种瞬态光栅技术：瞬态光栅衍射、瞬态光栅外差和光栅成像，利用它们测量GaAs/AlAs超晶格中的载流子扩散系数。每种技术都建立了理论模型来提取载流子扩散系数，三种技术的结果是一致的。我们的主要发现是：（1）瞬态光栅外差和光栅成像技术获得的瞬态透射变化ΔT/T0是相同的，即使这两种技术源自不同的检测原理；