Theoretical Study on C Adsorbate at Graphene/Cu(111) or h-BN/Cu(111) Interfaces

To elucidate bottom-up fabrication of heterostructures of two-dimensional materials such as graphene and h-BN, C atom adsorption on Cu(111) surface partially covered with h-BN or graphene is studied by using the first-principles method with van der Waals correction. It is found that the C monomer more difficultly locates under h-BN than under graphene or on bare Cu, while the C monomer also more hardly diffuses under graphene than under h-BN or on bare Cu. In addition, formation of C dimers is more difficult under graphene than under h-BN or on bare Cu. These results suggest that we can control the heterostructure growth by modulating growth condition. It is further found that the shape of h-BN or graphene flake on the Cu surface depends on whether the edge is terminated with hydrogen (H) or not. Because the bond formation energy of edges with H atoms are different between h-BN and graphene, it is indicated that appropriate choice of H condition will lead us to the intentional formation of lateral and vertical heterostructures.