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 photocurrent 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. An infrared photodetector based on in-plane BP p-n homojunction was investigated, and displayed an improved photo response resulted from the built-in electric field effect. Interestingly, the BP p-n photodetector exhibits visible-infrared dual-band detection with well separated spectral response. [Display omitted] •The p-n homojunction photodetector based on a single piece of BP film was realized by simply depositing part of the BP flake with a layer of SixNy film.•The photoresponsivity of the BP p-n junction under 1550 nm displays a 50 fold improvement. The response time of BP p-n homojunction photodetector is 35 μs, which is two orders of magnitude improvement than the pristine BP and lateral homogeneous BP p-n junction.•The BP p-n photodetector displays visible-infrared dual-band detection with well separated spectral response, opening up a possibility of the intelligent identification of infrared targets, for upgrading the capacity of reconnaissance in a complex environment.