Widely tunable electronic properties in graphene/two-dimensional silicon carbide van der Waals heterostructures

摘要

Heterostructures based on two-dimensional (2D) materials have attracted considerable research interest recently. Detailed structural and electronic characterization of graphene and 2D silicon carbide (graphene/2D-SiC) van der Waals heterostructure based on first-principles density functional theory calculations is presented herein. Different staking patterns as well as different orientations are proposed for such graphene/2D-SiC bilayer structures. The band structures of all the representational configurations exhibit a direct band gap ranging from 20 meV to 28 meV at the Dirac point. Charge carrier transfer and sublattice symmetry breaking are considered to be the key effects opening the band gap for each structure. For further tuning of the band gap, tensile biaxial strain is applied, resulting in a change in the band gap from 15 to 28 meV. The band gap can also be tuned by changing the interlayer distance between the graphene and SiC. The projected density of states and space charge distribution near the conduction and valence bands reflect the key role of graphene in shaping the electronic properties of the heterobilayers, implying the potentiality of 2D-SiC as a compatible substrate as well. These findings highlight a new avenue of research towards the application of graphene-based heterobilayers in future nanoelectronic devices.