Unipolar barrier structures are used to suppress dark current in photodetectors by blocking majority carriers. Designing unipolar barriers with conventional materials is challenging due to the strict requirements of lattice and band matching. Two-dimensional materials have self-passivated surfaces and tunable band structures, and can thus be used to design unipolar barriers in which lattice mismatch and interface defects are avoided. Here, we show that band-engineered van der Waals heterostructures can be used to build visible and mid-wavelength infrared unipolar barrier photodetectors. Our nBn unipolar barrier photodetectors, which are based on a tungsten disulfide/hexagonal boron nitride/palladium diselenide heterostructure, exhibit a low dark current of 15 pA, a photocurrent of 20 μA and a detectivity of 2.7 × 1012 cm Hz1/2 W−1. Our pBp unipolar barrier photodetectors, which are based on a black phosphorus/molybdenum disulfide/graphene heterostructure, exhibit a room-temperature detectivity of 2.3 × 1010 cm Hz1/2 W−1 in the mid-wavelength infrared region under blackbody radiation. The pBp devices also show a dichroic ratio of 4.9 under blackbody radiation, and a response time of 23 μs under 2 μm laser illumination.
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Data that support the findings of this study are available from the corresponding authors upon reasonable request. Source data are provided with this paper.
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W.H. acknowledges support from the National Natural Science Foundation of China (grant nos. 61725505, 11734016 and 61521005), National Key Research and Development Programme of China (grant no. 2020YFB2009300), Research Project of Frontier Science of CAS (grant no. QYZDB-SSW-JSC031) and Fund of Shanghai Natural Science Foundation (grant no. 19XD1404100). Yunfeng Chen and Z.W. acknowledge support from the Fund of SITP Innovation Foundation (grant nos. CX-235 and 348).
The authors declare no competing interests.
Peer review information Nature Electronics thanks Jiansheng Jie and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Chen, Y., Wang, Y., Wang, Z. et al. Unipolar barrier photodetectors based on van der Waals heterostructures. Nat Electron 4, 357–363 (2021). https://doi.org/10.1038/s41928-021-00586-w
npj 2D Materials and Applications (2022)
Light: Science & Applications (2022)
Nature Electronics (2022)
Science China Physics, Mechanics & Astronomy (2022)