Interface contact and modulated electronic properties by in-plain strains in a graphene-MoS₂ heterostructure

Designing a specific heterojunction by assembling suitable two-dimensional (2D) semiconductors has shown significant potential in next-generation micro-nano electronic devices. In this paper, we study the structural and electronic properties of graphene-MoS₂ (Gr-MoS₂) heterostructures with in-plain biaxial strain using density functional theory. It is found that the interaction between graphene and monolayer MoS₂ is characterized by a weak van der Waals interlayer coupling with the stable layer spacing of 3.39 Å and binding energy of 0.35 J m^-2. In the presence of MoS₂, the linear bands on the Dirac cone of graphene are slightly split. A tiny band gap about 1.2 meV opens in the Gr-MoS₂ heterojunction due to the breaking of sublattice symmetry, and it could be effectively modulated by strain. Furthermore, an n-type Schottky contact is formed at the Gr-MoS₂ interface with a Schottky barrier height of 0.33 eV, which can be effectively modulated by in-plane strain. Especially, an n-type ohmic contact is obtained when 6% tensile strain is imposed. The appearance of the non-zero band gap in graphene has opened up new possibilities for its application and the ohmic contact predicts the Gr-MoS₂ van der Waals heterojunction nanocomposite as a competitive candidate in next-generation optoelectronics and Schottky devices.