Sub-pA dark current infrared photodetection enabled by polarized water-intercalated heterojunctions
Chang Liu, Lin Tang, Yawei Lv, Long Chen, Yilu Qin, Sen Zhang, Shihao Zhao, Shuimei Ding, Xin Zhang, Xu Pan, Chao Ma, Xingqiang Liu, Fang Wang, Peng Wang, Xudong Wang, Yuan Liu, Enge Wang, Lei Liao, Xuming Zou
Abstract
Barrier detectors such as nBn and pBp architectures (formed by a n- or p-type contact layer, a barrier layer and a n- or p-type absorber) aim to block one carrier type while allowing the other to pass, but require complex hetero-integration and precise band engineering. Here, we propose an ultra-thin polar barrier strategy using a 0.75 nm water-intercalated WSe2/H2O/PdSe2 heterostructure. The confined water layer forms a clean, well-ordered interface and further generates a precisely oriented polarization field that depletes electrons in WSe2, significantly suppressing dark current to sub-pA levels across all biases, while enabling efficient tunneling of photogenerated holes. The device shows broadband photoresponse from the ultraviolet to mid-wave infrared (MWIR), with a room-temperature average detectivity exceeding 10¹⁰ cm Hz¹/² W⁻¹ in the MWIR. It also features ultrafast response (~3 μs), polarization light sensitivity, and two-year stability. Our work establishes a platform for high-performance infrared photodetection via van der Waals gap engineering. van der Waals unipolar barrier heterostructures hold promise for high-performance infrared detection, but their design requires further optimization. Here, the authors report the realization of polarized water-intercalated WSe2/H2O/PdSe2 photodetectors, showing sub-pA dark currents and broadband high-performance photoresponse.