Cooling Growth of Millimeter-Size Single-Crystal Bilayer Graphene at Atmospheric Pressure

Single-crystal bilayer graphene is attractive for functional electronic and photonic devices because of its high carrier mobility as well as a tunable band gap induced by a perpendicular electric field. Chemical vapor deposition (CVD) has been increasingly reported for the production of single-crystal bilayer graphene, but it is limited with respect to grain size because of nonsynchronic growth between the second layer and the first layer of bilayer graphene. In this research, we established a nonisothermal atmosphere CVD (NI-APCVD) system to realize synchronization of nucleation and growth of single-crystal bilayer graphene that contains the surface adsorption for the decomposed carbons and the shallow bulk phase segregation for the dissolved carbons. Based on the above process engineering, we successfully produced large hexagonal single-crystal bilayer graphene (similar to 1.0 mm) on the polycrystalline Cu foils. This work paves a pathway to the synchronous growth of wafer-scale single-crystal bilayer graphene, which is used for optimized graphene device fabrication.