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 fiel

In this study, we present a photodetector based on a van der Waals PN heterojunction, which utilizes p-type black phosphorus and n-type molybdenum telluride integrated on a silicon nitride waveguide. The PN heterojunction creates an electric field that effectively suppresses dark current and enhances responsivity. With a bias of 1 V from n-type molybdenum telluride to p-type black phosphorus, the dark current is less than 7 nA, which is more than two orders of magnitude lower than previously reported in other waveguide-integrated black phosphorus photodetectors. The photodetector exhibits an intrinsic responsivity of up to 577 mA W−1. Interestingly, the van der Waals PN heterojunction can be tuned via electrostatic doping to enhance rectification and further improve photodetection, resulting in an increased responsivity of 709 mA W−1. Additionally, the heterojunction photodetector demonstrates a response bandwidth of approximately 1.0 GHz and uniform photodetection across a wide spectral range, as confirmed by experimental measurements from 1500 to 1630 nm