Terahertz Conductivity Analysis for Highly Doped Thin-Film Semiconductors
Terahertz Conductivity Analysis for Highly Doped Thin-Film Semiconductors
复制标题
高掺杂薄膜半导体的太赫兹电导率分析
DOI：
10.1007/s10762-020-00739-6
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
M. Johnston
中科院分区：
文献类型：
--
作者：
Aleksander M. Ulatowski;L. Herz;M. Johnston
半导体薄膜的太赫兹透射特性分析是研究新型材料光电特性的一个很好的工具。太赫兹时域光谱（THz-TDS）可以提供有关晶体声子模式的信息，以及样品的电导率。光泵浦太赫兹探测（optical-pump-THz-probe，OPTP）技术与光激发技术相结合，可以用来研究半导体的瞬态光电导特性，揭示光激发载流子的动力学和迁移率。由于材料的电导率和太赫兹传输函数之间的关系通常是复杂的，已经开发了简单的解析表达式，以使直接计算的频率依赖性的电导率从太赫兹-TDS数据在光学薄样品的制度。在这里，我们评估了这些近似解析公式在高掺杂半导体薄膜中的准确性，发现在背景电导率为102Ω− 1cm− 1的材料中，计算的光电导与其实际值存在显着偏差。我们提出了一种替代的解析表达式，这大大提高了准确性的估计值的真实的光电导，同时保持简单的实验实现。我们的近似在暗电导率高达104Ω− 1cm− 1的薄膜中仍然有效，并且为计算光电导率高达104Ω− 1cm− 1提供了非常高的精度，因此对于电掺杂半导体中光激发载流子动力学的研究具有高度相关性。以碘化锡钙钛矿的重掺杂薄膜为例，我们展示了一种简单的实验方法来实现我们的校正，并发现常用的光电导表达式可能会导致电荷载流子迁移率被低估超过50%。
The analysis of terahertz transmission through semiconducting thin films has proven to be an excellent tool for investigating optoelectronic properties of novel materials. Terahertz time-domain spectroscopy (THz-TDS) can provide information about phonon modes of the crystal, as well as the electrical conductivity of the sample. When paired with photoexcitation, optical-pump-THz-probe (OPTP) technique can be used to gain an insight into the transient photoconductivity of the semiconductor, revealing the dynamics and the mobility of photoexcited charge carriers. As the relation between the conductivity of the material and the THz transmission function is generally complicated, simple analytical expressions have been developed to enable straightforward calculations of frequency-dependent conductivity from THz-TDS data in the regime of optically thin samples. Here, we assess the accuracy of these approximated analytical formulas in thin films of highly doped semiconductors, finding significant deviations of the calculated photoconductivity from its actual value in materials with background conductivity comparable to 102Ω− 1cm− 1. We propose an alternative analytical expression, which greatly improves the accuracy of the estimated value of the real photoconductivity, while remaining simple to implement experimentally. Our approximation remains valid in thin films with high dark conductivity of up to 104Ω− 1cm− 1and provides a very high precision for calculating photoconductivity up to 104Ω− 1cm− 1, and therefore is highly relevant for studies of photoexcited charge-carrier dynamics in electrically doped semiconductors. Using the example of heavily doped thin films of tin-iodide perovskites, we show a simple experimental method of implementing our correction and find that the commonly used expression for photoconductivity could result in an underestimate of charge-carrier mobility by over 50%.
影响因子：
7
作者：
Burdanova, Maria G.;Tsapenko, Alexey P.;Lloyd-Hughes, James
通讯作者：
Lloyd-Hughes, James
DOI：
10.1007/s10762-018-0538-7
发表时间：
2018-12-01
影响因子：
2.9
作者：
Davies, Christopher L.;Patel, Jay B.;Johnston, Michael B.
通讯作者：
Johnston, Michael B.