Topological Insulator Bi<sub>2</sub>Se<sub>3</sub> Heterojunction with a Low Dark Current for Midwave Infrared Photodetection
Tiange Zhao, Yue Chen, Tengfei Xu, Fang Zhong, Yiye Yu, Hang Ma, Kun Zhang, Shikun Duan, Jiapeng Hu, Shi‐Cheng Wang, Jiaxiang Guo, Zhen Wang
Abstract
Broadband photodetection including midwave infrared (MWIR) is crucial in space science and technology. Topological insulators Bi 2 Se 3 have exhibited excellent performance in infrared. However, the large dark current caused by topological surface states impedes further photodetection capability enhancement. Here, we designed and integrated the Bi 2 Se 3 /BP van der Waals p-n heterojunction to suppress dark current. The built-in electric field and clean, sharp interface at heterojunctions drive excellent photoresponse of the Bi 2 Se 3 /BP photodetector from visible to mid-infrared (520–4250 nm) with the fastest response time reaching 92 μs (τ rising ) and 84 μs (τ falling ), 3 orders of magnitude faster than Bi 2 Se 3 detector. The responsivity ( R ) and detectivity ( D *) can reach up to 1.13 A W -1 and 7.8 × 10 9 cm Hz 1/2 W -1, respectively, at 2 μm under 0 bias. Due to the asymmetric lattice structure of BP, the heterojunction device displays outstanding polarization-resolved photoelectric response, with a polarization ratio of up to 20.1 at 2 μm. Moreover, the device exhibits a significant blackbody response and excellent imaging capabilities. This work may pave a way for designing high-performance midwave infrared photodetectors.