Properties of Graphene/h-BN Superlattices Measured with Active Angle Control of Crystal Alignment

Van der Waals (vdW) heterostructures have drawn wide interest as an excellent platform to investigate material properties subjected to a periodic potential. In graphene/hexagonal boron nitride lattice scale mismatch gives rise to naturally occurring superlattice potential in the form of a moiré pattern. This results in significant modification of the band structure of graphene yielding new local mini-gaps and a gapped charge neutrality point. These new properties have a critical dependence on the rotational alignment of the layers, yet to date experimental studies of these effects have been limited by the uncontrollability of the relative crystallographic orientation. Here we present optical, electronic and mechanical properties of h-BN/graphene superlattices measured on the same device owing to the ability of actively controlling the crystal lattice alignment. Combining a dry transfer process, to assemble high quality heterostructures, and the use of an AFM in contact mode, we achieved a precise control of ~0.2 degree of the relative crystallographic orientation of the h-BN/graphene superlattice. We demonstrate results consistent with previous works and report new observations by taking advantage of the on-demand angle control of the h-BN/graphene superlattice.