Influence of Hexagonal Boron Nitride on Electronic Structure of Graphene

By performing first-principles calculations, we studied hexagonal-boron-nitride (hBN)-supported graphene, in which moire structures are formed due to lattice mismatch or interlayer rotation. A series of graphene/hBN systems has been studied to reveal the evolution of properties with respect to different twisting angles (21.78 degrees, 13.1 degrees, 9.43 degrees, 7.34 degrees, 5.1 degrees, and 3.48 degrees). Although AA- and AB-stacked graphene/hBN are gapped at the Dirac point by about 50 meV, the energy gap of the moire graphene/hBN, which is much more asymmetric, is only about several meV. Although the Dirac cone of graphene residing in the wide gap of hBN is not much affected, the calculated Fermi velocity is found to decrease with the increase in the moire super lattice constant due to charge transfer. The periodic potential imposed by hBN modulated charge distributions in graphene, leading to the shift of graphene bands. In agreement with experiments, there are dips in the calculated density of states, which get closer and closer to the Fermi energy as the moire lattice grows larger.

Automated summary

The study investigates the properties of graphene supported by hBN and forming moiré structures, revealing changes in energy gaps and Fermi velocity with twisting angles. The periodic potential imposed by hBN affects charge distributions in graphene, influencing band structures.