Towards growth of pure AB-stacked bilayer graphene single crystals

Given its intriguing band structure and unique tunable bandgap, AB-stacked bilayer graphene has great potentials in the applications of high-end electronics, optoelectronics and semiconductors. The epitaxial growth of AB-stacked single-crystal bilayer graphene films requires a strict AB-stacked lattice, identical orientations and seamless stitching of bilayer graphene islands. However, the particles inevitably present on the metal surface that produced during high temperature growth would induce random orientations, twisted stacking islands, and uncontrollable multilayers, which is a great challenge to overcome. Here, we propose a heat-resisting-box assisted strategy to produce nearly pure AB-stacked bilayer graphene single-crystal films on Cu/Ni (111) foils. With our technique, the particles on the Cu/Ni (111) surface are effectively eliminated, which greatly minimizes the occurrence of randomly twisted islands and uncontrollable multilayers. The as-grown AB-stacked bilayer graphene films show > 99% alignment and > 99% AB stacking order. Our work provides a promising method towards the growth of pure AB-stacked bilayer graphene single crystals and would accelerate its device applications.