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^− 1 and 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%.

已经证明，通过半导体薄膜进行太赫兹传输的分析是研究新型材料的光电性能的绝佳工具。太赫兹时域光谱（THz-TDS）可以提供有关晶体的声子模式以及样品电导率的信息。与光激发配合使用时，可以使用光泵THz探针（OPTP）技术来洞察半导体的瞬态光电导性，从而揭示光激发电荷载流子的动力学和迁移率。由于材料的电导率和THz传输函数之间的关系通常很复杂，已经开发出了简单的分析表达式，可以在光学薄样品的情况下根据THz-TDS数据直接计算频率相关的电导率。在这里，我们评估了在高掺杂半导体薄膜中这些近似分析公式的准确性，发现在背景电导率可比为10的材料中，计算出的光电导率与其实际值存在显着偏差² Ω ^{- 1}厘米^{- 1}。我们提出了一种替代的分析表达式，可以极大地提高实际光电导率估计值的准确性，同时仍然易于通过实验实现。我们的近似保持在薄膜与最多的高暗电导率至10有效⁴ Ω ^{- 1}厘米^{- 1}，并提供了非常高的精确度来计算光电导性高达10 ⁴ Ω ^{- 1}厘米^{- 1}因此，与研究电掺杂半导体中的光激发电荷载流子动力学非常相关。以重掺杂的碘化锡钙钛矿薄膜为例，我们展示了一种实现校正的简单实验方法，发现常用的光电导表达式可能导致电荷载流子迁移率低估50％以上。