He Jiajing, Liu Huayou, Huang Chulin, Jia Yueyang, Li Kai, Mesli Abdelmadjid, Yang Rui, He Yongning, Dan Yaping
University of Michigan-Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240, China.
School of Microelectronics, Xi'an Jiao Tong University, Xi'an, Shaanxi 710049, China.
ACS Nano. 2021 Dec 28;15(12):20242-20252. doi: 10.1021/acsnano.1c08331. Epub 2021 Nov 19.
Low-dimensional photodetectors, in particular those in photoconductive mode, often have extraordinarily high photogain. However, high gain always comes along with a slow frequency response. The gain-bandwidth product (GBP) is a figure of merit to evaluate the performance of a photodetector. Whether the high-gain photoconductors can outperform standard PIN photodiodes in terms of GBP remains an open question. In this article, we derived the analytical transient photoresponses of nanowire photoconductors which were validated with the simulations and experiments. Surprisingly, the fall transients do not follow a simple time-dependent exponential function except for some special cases. Given the analytical photogains that were established previously, we derived the theoretical GBP of high-gain nanowire photoconductors. Analysis of the analytical GBP indicates that nanoscale photoconductors, although having extremely high gain, will never outperform typical PIN photodiodes in terms of GBP.
低维光电探测器，尤其是处于光电导模式的那些，通常具有极高的光增益。然而，高增益总是伴随着缓慢的频率响应。增益带宽积（GBP）是评估光电探测器性能的一个品质因数。高增益光电导体在GBP方面是否能超越标准PIN光电二极管仍是一个悬而未决的问题。在本文中，我们推导了纳米线光电导体的解析瞬态光响应，并通过模拟和实验进行了验证。令人惊讶的是，除了一些特殊情况外，下降瞬态并不遵循简单的时间相关指数函数。基于先前建立的解析光增益，我们推导了高增益纳米线光电导体的理论GBP。对解析GBP的分析表明，纳米级光电导体尽管具有极高的增益，但在GBP方面永远无法超越典型的PIN光电二极管。
