Ultrahigh-photoresponsive UV photodetector based on a BP/ReS₂ heterostructure p–n diode

The van der Waals (vdW) heterostructure, made up of two dissimilar two-dimensional materials held together by van der Waals interactions, has excellent electronic and optoelectronic properties as it provides a superior interface quality without the lattice mismatch problem. Here, we report the development and photoresponse characteristics of a p–n diode based on a stacked black phosphorus (BP) and rhenium disulfide (ReS₂) heterojunction. The heterojunction showed a clear gate-tunable rectifying behavior similar to that of the conventional p–n junction diode. Under UV illumination, the BP/ReS₂ p–n diode displayed a high photoresponsivity of 4120 A W⁻¹ and we were able to modify the photoresponse properties by adjusting the back gate voltage. Moreover, an investigation of various channel lengths yielded the highest photoresponsivity of 11 811 A W⁻¹ for a BP length of 1 μm. These results suggested vdW 2D materials to be promising for developing advanced heterojunction devices for nano-optoelectronics.