Integration of 2D Black Phosphorus Phototransistor and Silicon Photonics Waveguide System Towards Mid-Infrared On-Chip Sensing Applications

We demonstrate the first black phosphorus phototransistor integrated with Si photonics waveguide system towards mid-infrared (MIR) sensing. At a wavelength of 3.78 µm, the black phosphorus phototransistor achieves a high responsivity of 0.7 A/W under a small drain bias of −1 V at room-temperature. Additionally, the device offers gate and drain bias tunability to suppress dark current while simultaneously optimize photo-response performance. Our results reveal the potential of black phosphorus for MIR detection to enable the realization of integrated on-chip systems for MIR sensing applications.