Pit formation with graphene growth on copper foils by ethanol chemical vapor deposition

Long-time chemical vapor deposition (CVD) with ethanol was carried out for the growth of graphene films on copper (Cu) foils. Multilayer graphene like graphite is formed on Cu surface. Interestingly, some pits with unique shapes are produced at defective parts such as nucleation sites and grain boundaries of grown multilayer graphene, and single-layer graphene is formed only on the pit bottom with the square shape. The pits are produced by the oxidation and reduction of Cu surface due to the long-time reaction with ethanol and vacuum process in the CVD. The square shape of the pit bottom is related to the symmetry of (100) crystallographic plane of Cu underneath the oxidation layer. The clean (100) surface of Cu appears on the pit bottom after the reduction, and single-layer graphene is formed on the clean surface. The pit formation accompanied by graphene growth occurs in the ethanol CVD process. Such synthesis process by the ethanol CVD can provide an insight for the growth control and patterning for graphene. [Display omitted] •Long-time CVD with ethanol on Cu foils was investigated for the synthesis of graphene.•Unique pits with square shape are formed with the growth of multilayer graphene.•Single-layer graphene is obtained only on the clean Cu surface of the pit bottom.•Pit formation with graphene growth is due to the oxidation and reduction of Cu foil.