Two-dimensional materials are attractive for constructing high-performance photonic chip-integrated photodetectors because of their remarkable electronic and optical properties and dangling-bond-free surfaces.However,the reported chip-integrated two-dimensional material photodetectors were mainly implemented with the configuration of metal-semiconductor-metal,suffering from high dark currents and low responsivities at high operation speed.Here,we report a van der Waals PN heterojunction photodetector,composed of p-type black phosphorous and n-type molybdenum telluride,integrated on a silicon nitride waveguide.The built-in electric field of the PN heterojunction significantly suppresses the dark current and improves the responsivity.Under a bias of 1 V pointing from n-type molybdenum telluride to p-type black phosphorous,the dark current is lower than 7 nA,which is more than two orders of magnitude lower than those reported in other waveguide-integrated black phosphorus photodetectors.An intrinsic responsivity up to 577 mA W-1 is obtained.Remarkably,the van der Waals PN heterojunction is tunable by the electrostatic doping to further engineer its rectification and improve the photodetection,enabling an increased responsivity of 709 mA W-1.Besides,the heterojunction photodetector exhibits a response bandwidth of～1.0GHz and a uniform photodetection over a wide spectral range,as experimentally measured from 1500 to 1630 nm.The demonstrated chip-integrated van der Waals PN heterojunction photodetector with low dark current,high responsivity and fast response has great potentials to develop high-performance on-chip photodetectors for various photonic integrated circuits based on silicon,lithium niobate,polymer,etc.

Ruijuan Tian;Xuetao Gan;Chen Li;Xiaoqing Chen;Siqi Hu;Linpeng Gu;Dries Van Thourhout;Andres Castellanos-Gomez;Zhipei Sun;Jianlin Zhao

Key Laboratory of Light Field Manipulation and Information Acquisition,Ministry of Industry and Information Technology,and Shaanxi Key Laboratory of Optical Information Technology,School of Physical Science and Technology,Northwestern Polytechnical University,710129 Xi'an,China;Photonics Research Group and Center for Nano and Biophotonics,Ghent University,B-9000 Gent,Belgium;Materials Science Factory,Instituto de Ciencia de Materiales de Madrid(ICMM-CSIC),E-28049 Madrid,Spain;Department of Electronics and Nanoengineering and QTF Centre of Excellence,Aalto University,Fl-02150 Espoo,Finland

光：科学与应用（英文版）

[1]Ruijuan Tian;Xuetao Gan;Chen Li;Xiaoqing Chen;Siqi Hu;Linpeng Gu;Dries Van Thourhout;Andres Castellanos-Gomez;Zhipei Sun;Jianlin Zhao-.Chip-integrated van der Waals PN heterojunction photodetector with low dark current and high responsivity)[J].光：科学与应用（英文版）,2022(05):901-910

responsivities

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