Shen Yinchu, He Jiajing, Xu Yang, Wang Kaiyou, Dan Yaping
University of Michigan - Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai, 200240, China.
Aerospace Laser Technology and System Department, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai, 201800, China.
Small. 2024 Nov;20(45):e2402682. doi: 10.1002/smll.202402682. Epub 2024 Jul 26.
Low-dimensional photoconductors have extraordinarily high photoresponse and gain, which can be modulated by gate voltages as shown in literature. However, the physics of gate modulation remains elusive. In this work, the physics of gate modulation in silicon nanowire photoconductors with the analytical photoresponse equations is investigated. It is found that the impact of gate voltage varies vastly for nanowires with different size. For the wide nanowires that cannot be pinched off by high gate voltage, it is found that the photoresponses are enhanced by at least one order of magnitude due to the gate-induced electric passivation. For narrow nanowires that starts with a pinched-off channel, the gate voltage has no electric passivation effect but increases the potential barrier between source and drain, resulting in a decrease in dark and photocurrent. For the nanowires with an intermediate size, the channel is continuous but can be pinched off by a high gate voltage. The photoresponsivity and photodetectivity is maximized during the transition from the continuous channel to the pinched-off one. This work provides important insights on how to design high-performance photoconductors.
低维光电导体具有极高的光响应和增益，如文献所示，其可通过栅极电压进行调制。然而，栅极调制的物理机制仍然难以捉摸。在这项工作中，利用解析光响应方程对硅纳米线光电导体中的栅极调制物理机制进行了研究。结果发现，对于不同尺寸的纳米线，栅极电压的影响差异很大。对于高栅极电压无法夹断的宽纳米线，发现由于栅极诱导的电钝化作用，光响应增强了至少一个数量级。对于起始于夹断沟道的窄纳米线，栅极电压没有电钝化作用，但会增加源极和漏极之间的势垒，导致暗电流和光电流减小。对于中等尺寸的纳米线，沟道是连续的，但可被高栅极电压夹断。在从连续沟道向夹断沟道转变的过程中，光响应度和光探测率达到最大值。这项工作为如何设计高性能光电导体提供了重要的见解。
