First principles study of van der Waals heterobilayers

摘要

This paper presents a comparative first principles study of van derWaals heterobilayers derived from thecoupling of graphene to silicon carbide and hexagonal boron nitride monolayer. Using the local, semilocal,and van der Waals interaction-corrected density functional theory, it found that the adhesionenergy of graphene on SiC and h-BN monolayer is invariant under dispersion corrections. On the otherhand, considerably more accurate interlayer distances are obtained using the semi-empirical DFT-D3correction, whereas non-local corrections consistently yield higher adhesion energies of 3.70 and2.84 mRyd per carbon for graphene on SiC and h-BN monolayer substrates. It is also observed that theanisotropy induced band gap depends on the evolution of the stacking sequence of heterobilayers underpersistent strain. It is suggested that the delicate minimisation of the overlap interactions betweeninterlayer p-bonds induces localised charge puddles in the interfacial electronic structure and opens up aband gap. Using the dependence of the induced band gap on network anisotropy, it is shown that the sizeof the band gap is tunable by controlling the stacking sequence and the strength of the dipole-inducedelectric field within the heterobilayer interface.