Hexagonal boron nitride/bilayer graphene moir\'e superlattices in the Dirac-material family: energy-band engineering and carrier doping by dual gating

Abstract

We review the fabrication and transport characterization of hexagonal boron nitride (hBN)/Bernal bilayer graphene (BLG) moir\'e superlattices. Due to the moir\'e effect, the hBN/BLG moir\'e superlattices exhibit an energy gap at the charge neutrality point (CNP) even in the absence of a perpendicular electric field. In BLG, the application of a perpendicular electric field tunes the energy gap at the CNP, which contrasts with single-layer graphene and is similar to the family of rhombohedral multilayer graphene. The hBN/BLG moir\'e superlattice is associated with non-trivial energy-band topology and a narrow energy band featuring a van Hove singularity. By employing a dual-gated device structure where both the perpendicular displacement field and the carrier density are individually controllable, systematic engineering of the energy-band structure can be achieved. The data presented here demonstrate the universality and diversity in the physics of hBN/BLG moir\'e superlattices.