Pressure-controlled chemical vapor deposition of single-layer graphene with millimeter-size domains on thin Cu film

In this work, single-layer graphene with compact millimeter-size domains has been obtained by chemical vapor deposition (CVD) on thin Cu film. This has been achieved by carefully adjusting the global pressure inside the CVD furnace as the graphene synthesis protocol proceeds. Global pressures in the 2–750 mbar range have been systematically investigated to determine optimal conditions for both the Cu annealing and the graphene nucleation and growth steps. It has been observed that using a high global pressure during the graphene growth is essential to grow defect-free compact domains. The low nucleation site density, required to produce large graphene domains, has been achieved by combining a high hydrogen-to-methane ratio during the graphene growth step and an in situ Cu film oxidation induced by a high pressure level of argon during the Cu annealing step. Finally, it is found that a brief evacuation of the CVD furnace from its argon atmosphere prior to the graphene growth step is a key process step to prevent the Cu film degradation. Our method provides a scalable and reproducible way to produce high quality graphene on thin Cu film which is a convenient platform for the realization of graphene-based practical applications