Phys.org  May 13, 2022 Chip-integrated two-dimensional material photodetectors implemented with the configuration of metal-semiconductor-metal suffer from high dark currents and low responsivities at high operation speed. An international team of researchers (China, Belgium, Spain, Finland) has developed 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. 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 […]