Tuning photoresponse of graphene-black phosphorus heterostructure by electrostatic gating and photo-induced doping

Metal-semiconductor diodes constructed from two-dimensional (2D) van der Waals heterostructures show excellent gate electrostatics and a large built-in electric field at the tunnel junction, which can be exploited to make highly sensitive photodetector. Here we demonstrate a metal-semiconductor photodiode constructed by the monolayer graphene (Gr) on a few-layer black phosphorus (BP). Due to the presence of a built-in potential barrier (similar to 0.09 +/- 0.03 eV) at the Gr-BP interface, the photoresponsivity of the Gr-BP device is enhanced by a factor of 672%, and the external quantum efficiency (EQE) increases to 648% from 84% of the bare BP. Electrostatic gating allows the BP channel to be switched between p-type and n-type conduction. We further demonstrate that excitation laser power can be used to control the current polarity of the Gr-BP device due to photon-induced doping. The versatility of the Gr-BP junctions in terms of electrostatic bias-induced or light-induced switching of current polarity is potentially useful for making dynamically reconfigurable digital circuits. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.