Yu Huihui, Wang Yunan, Zeng Haoran, Cao Zhihong, Zhang Qinghua, Gao Li, Hong Mengyu, Wei Xiaofu, Zheng Yue, Zhang Zheng, Zhang Xiankun, Zhang Yue
Academy for Advanced Interdisciplinary Science and Technology, Key Laboratory of Advanced Materials and Devices for Post-Moore Chips Ministry of Education, State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, P. R. China.
Beijing Advanced Innovation Center for Materials Genome Engineering, School of Materials Science and Engineering, Beijing Key Laboratory for Advanced Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083, P. R. China.
ACS Nano. 2024 Jul 2;18(26):17100-17110. doi: 10.1021/acsnano.4c03729. Epub 2024 Jun 20.
Two-dimensional (2D) van der Waals (vdWs) heterojunctions have been actively investigated in low-power-consumption and fast-response photodiodes owing to their atomically smooth interfaces and ultrafast interfacial charge transfer. However, achieving ultralow dark current and ultrafast photoresponse in the reported photovoltaic devices remains a challenge as the large built-in electric field in a heterojunction can not only speed up photocarrier transport but also increase the minority-carrier dark current. Here, we propose a high-spike barrier photodiode that can achieve both an ultralow dark current and an ultrafast response. The device is fabricated by the Te/WS heterojunction, while the band alignment can transition from type-II to type-I with a high electron barrier and a large hole built-in electronic field. The high electron barrier can greatly reduce the drift current of minority carriers and the generation current of the thermal carriers, while the large built-in electronic field can still speed up the photocarrier transport. The designed Te/WS vdWs photodiode yields an ultralow dark current of 8 × 10 A and an ultrafast photoresponse of 10/13 μs. Furthermore, a high-performance visible-light imager with a pixel resolution of 100 × 40 is demonstrated using the Te/WS vdWs photodiode. This work provides a comprehensive understanding of designing 2D-material-based photovoltaics with excellent overall performance.
二维（2D）范德华（vdWs）异质结由于其原子级光滑的界面和超快的界面电荷转移，已在低功耗和快速响应的光电二极管中得到了积极研究。然而，在所报道的光电器件中实现超低暗电流和超快光响应仍然是一个挑战，因为异质结中的大内置电场不仅可以加速光载流子传输，还会增加少数载流子暗电流。在此，我们提出了一种高尖峰势垒光电二极管，它可以同时实现超低暗电流和超快响应。该器件由Te/WS异质结制成，其能带排列可以从II型转变为I型，具有高电子势垒和大的空穴内置电场。高电子势垒可以大大降低少数载流子的漂移电流和热载流子的产生电流，而大的内置电场仍然可以加速光载流子传输。所设计的Te/WS vdWs光电二极管产生8×10 A的超低暗电流和10/13 μs的超快光响应。此外，使用Te/WS vdWs光电二极管展示了一种像素分辨率为100×40的高性能可见光成像器。这项工作为设计具有优异整体性能的基于二维材料的光电器件提供了全面的理解。
