Large-Scale Ultrathin 2D Wide-Bandgap BiOBr Nanoflakes for Gate-Controlled Deep-Ultraviolet Phototransistors

Chuanhui Gong; Junwei Chu; Shifeng Qian; Chujun Yin; Xiaozong Hu; Hongbo Wang; Yang Wang; Xiang Ding; Shangchi Jiang; Alei Li; Youpin Gong; Xianfu Wang; Chaobo Li; Tianyou Zhai; Jie Xiong

doi:10.1002/adma.201908242

Large-Scale Ultrathin 2D Wide-Bandgap BiOBr Nanoflakes for Gate-Controlled Deep-Ultraviolet Phototransistors

Adv Mater. 2020 Mar;32(12):e1908242. doi: 10.1002/adma.201908242. Epub 2020 Feb 19.

Authors

Chuanhui Gong¹, Junwei Chu¹, Shifeng Qian², Chujun Yin^{3

4}, Xiaozong Hu⁵, Hongbo Wang¹, Yang Wang¹, Xiang Ding¹, Shangchi Jiang⁶, Alei Li⁷, Youpin Gong⁷, Xianfu Wang¹, Chaobo Li^{3

4}, Tianyou Zhai⁵, Jie Xiong¹

Affiliations

¹ State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054, P. R. China.
² Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, P. R. China.
³ Institute of Microelectronics of Chinese Academy of Sciences, Beijing, 100029, P. R. China.
⁴ University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
⁵ State Key Laboratory of Material Processing and Die and Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China.
⁶ Technology Development Center, Metatest Optoelectronic CO. LTD, Nanjing, 210008, P. R. China.
⁷ Academy for Advanced Interdisciplinary Studies and Department of Physics, Southern University of Science and Technology, Shenzhen, 518055, China.

PMID: 32077189
DOI: 10.1002/adma.201908242

Abstract

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_λ , 12739.13 A W^-1 ), ultrahigh external quantum efficiency (EQE, 6.46 × 10⁶ %), and excellent detectivity (D*, 8.37 × 10¹² Jones) at 245 nm with a gate voltage (V_g ) of 35 V attributed to the photogating effects. The ultrafast response (τ_rise = 102 µs) can be achieved by utilizing photoconduction effects at V_g of -40 V. The combination of photocurrent generation mechanisms for BiOBr-based phototransistors controlled by V_g can pave a way for designing novel 2D optoelectronic materials to achieve optimal device performance.

Keywords: deep UV phototransistors; high gain; monolayer BiOBr; wide-bandgap semiconductors.

Abstract

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