High performance near infrared photodetector based on in-plane black phosphorus p-n homojunction

Black phosphorus (BP) has been considered as an appealing candidate for broadband photodetection from the visible to the infrared part of the spectrum owing to its tunable direct band gap and high carrier mobility. However, compared with other typical materials, the photoresponsivity of BP devices is rather weak. In this work, a near infrared photodetector with high performance based on in-plane BP p-n homojunction was investigated. The strong built-in electric field of the p-n junction can be modulated through bias and gate voltage, where the photo generated electron-hole pairs can be effectively separated, thus, leads to the enhanced photo-current and faster photoresponse. Compared with the pristine BP, the photoresponsivity of the BP p-n homojunction under 1550 nm displays a 50-fold increment. The response time of the in-plane BP p-n homojunction photodetector exhibits two orders of magnitude improvement than that of the pristine BP and other lateral homogeneous BP p-n junction. Fascinatingly, the BP p-n photodetector also displays visible-infrared dual-band detection with well separated spectral response, opening up a feasibility of the intelligent identification of infrared targets.