Interlayer coupling and electric field controllable Schottky barriers and contact types in graphene/PbI2 heterostructures

Van der Waals heterostructures, created by putting graphene on other two-dimensional semiconducting materials, have become an effective strategy to enhance the physical properties and extend the possible applications of two-dimensional (2D) materials. Motivated by the successful synthesis of a graphene/${\mathrm{PbI}}_{2}$ heterostructure in a recent experiment [Nat. Commun. 11, 823 (2020)], here we use first-principles calculations to construct and investigate the electronic properties and interface characteristics of graphene/${\mathrm{PbI}}_{2}$ heterostructure. We find that the weak forces occurring at the interface keep heterostructures stable and maintain the intrinsic properties of the constituent graphene and ${\mathrm{PbI}}_{2}$ monolayers. At the equilibrium interlayer distance of 3.48 \AA{}, the graphene/${\mathrm{PbI}}_{2}$ heterostructure forms an $n$-type Schottky contact. More interestingly, the Schottky barrier height and contact types in the graphene/${\mathrm{PbI}}_{2}$ heterostructure can be adjusted by electric field and interlayer coupling. The graphene/${\mathrm{PbI}}_{2}$ heterostructure can transform from a $n$-type Schottky contact to a $p$-type one or to Ohmic contact by applying electric field or by adjusting interlayer distance. The controllable electronic properties and contact types in graphene/${\mathrm{PbI}}_{2}$ heterostructure make it a promising candidate for designing and improving the performance of high-efficiency Schottky nanodevices.