Gong Chuanhui, Chu Junwei, Qian Shifeng, Yin Chujun, Hu Xiaozong, Wang Hongbo, Wang Yang, Ding Xiang, Jiang Shangchi, Li Alei, Gong Youpin, Wang Xianfu, Li Chaobo, Zhai Tianyou, Xiong Jie
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, P. R. China.
Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, P. R. China.
Adv Mater. 2020 Mar;32(12):e1908242. doi: 10.1002/adma.201908242. Epub 2020 Feb 19.
Ternary two-dimensional (2D) semiconductors with controllable wide bandgap, high ultraviolet (UV) absorption coefficient, and critical tuning freedom degree of stoichiometry variation have a great application prospect for UV detection. However, as-reported ternary 2D semiconductors often possess a bandgap below 3.0 eV, which must be further enlarged to achieve comprehensively improved UV, especially deep-UV (DUV), detection capacity. Herein, sub-one-unit-cell 2D monolayer BiOBr nanoflakes (≈0.57 nm) with a large size of 70 µm are synthesized for high-performance DUV detection due to the large bandgap of 3.69 eV. Phototransistors based on the 2D ultrathin BiOBr nanoflakes deliver remarkable DUV detection performance including ultrahigh photoresponsivity (R , 12739.13 A W ), ultrahigh external quantum efficiency (EQE, 6.46 × 10 %), and excellent detectivity (D*, 8.37 × 10 Jones) at 245 nm with a gate voltage (V ) of 35 V attributed to the photogating effects. The ultrafast response (τ = 102 µs) can be achieved by utilizing photoconduction effects at V of -40 V. The combination of photocurrent generation mechanisms for BiOBr-based phototransistors controlled by V can pave a way for designing novel 2D optoelectronic materials to achieve optimal device performance.
具有可控宽带隙、高紫外（UV）吸收系数和化学计量比变化关键调谐自由度的三元二维（2D）半导体在紫外探测方面具有广阔的应用前景。然而，已报道的三元2D半导体的带隙通常低于3.0 eV，必须进一步扩大以实现紫外，尤其是深紫外（DUV）探测能力的全面提升。在此，合成了尺寸为70 µm的亚单胞2D单层BiOBr纳米片（≈0.57 nm）用于高性能DUV探测，这归因于其3.69 eV的大带隙。基于2D超薄BiOBr纳米片的光电晶体管在245 nm、栅极电压（V）为35 V时展现出卓越的DUV探测性能，包括超高的光响应度（R，12739.13 A W）、超高的外量子效率（EQE，6.46×10%）和优异的探测率（D*，8.37×10 Jones），这归因于光门控效应。在V为 -40 V时，利用光电导效应可实现超快响应（τ = 102 µs）。由V控制的基于BiOBr的光电晶体管的光电流产生机制的结合可为设计新型2D光电子材料以实现最佳器件性能铺平道路。
