Asymmetric Surface-Dependent Graphene Growth on a Single Cu Foil via Chemical Vapor Deposition

This study investigates the graphene growth characteristics on both sides of a Cu foil during low-pressure chemical vapor deposition (CVD). By conforming the Cu foil to the curvature of the reactor’s quartz tube, two different local gas flow environments are created in a single process. The top surface, which is directly exposed to the precursor gas flow, exhibits rapid, high-density growth, achieving full monolayer coverage as fast as 1 min, approximately 10 times faster than that on the bottom surface. However, prolonged growth exceeding 5 min on the top surface also leads to bilayer growth. In contrast, the bottom surface, with a restricted gas supply, shows slower, low-density growth involving gradual coalescence of large, individual graphene islands into a complete monolayer. This work demonstrates that a single Cu foil can provide two distinct growth environments, enabling the simultaneous realization of both rapid, high-density and slow, low-density monolayer graphene growth within a single CVD process.