Increasing coverage of mono-layer graphene grown on hexagonal boron nitride.

Graphene sitting on hexagonal boron nitride (h-BN) always exhibits excellent electrical properties. And the properties of graphene on h-BN are often dominated by its domain size and boundaries. Chemical vapor deposition (CVD) is a promising approach to achieve large size graphene crystal. However, the CVD growth of graphene on h-BN still faces challenges in increasing coverage of monolayer graphene because of a weak control on nucleation and vertical growth. Here, an auxiliary source strategy is adapted to increase the nucleation density of graphene on h-BN and synthesis continuous graphene films. It is found that both silicon carbide and organic polymer e.g., methyl methacrylate can assist the nucleation of graphene, and then increases the coverage of graphene on h-BN. By optimizing the growth temperature, vertical accumulation of graphitic materials can be greatly suppressed. This work provides an effective approach for preparing continuous graphene film on h-BN, and may bring a new sight for the growth of high quality graphene.