▎ 摘　　要

In the wake of the considerable investigation of two-dimensional (2D) materials, van der Waals (vdW) heterostructures based on atomically thin 2D materials show large potential for functional electronic devices. Within the heterostructure, the contact barrier at the interface between two components directly affects the performance of the heterostructure. Here, by means of first-principle calculations, we took 2D graphene/InSe as a model to investigate the electronic properties and the contact behavior of a 2D metal-semiconductor contacting vdW heterostructure. We showed that there is an Ohmic contact between these two monolayers. It is highlighted that the band alignment between the two compounds can be effectively tuned by changing their interlayer distance. As a result, controllable types of contact in the graphene/InSe vdW heterostructure can be achieved, which is highly desirable for electronic and optoelectronic devices. Furthermore, nonequilibrium Green's function simulations demonstrate that the graphene/InSe heterostructure shows a distinguished photogenerated current. Our results may supply useful information for designing novel, high-performance electronic and optoelectronic devices based on van der Waals heterostructures.