Large-area synthesis of high-quality and uniform monolayer graphene without unexpected bilayer regions

Chemical vapor deposition is a promising method to synthesize the large area monolayer graphene. However, unexpected bilayer regions are easily formed on the monolayer graphene, which will dramatically degrade the quality and uniformity of graphene. In this work, the large-area, high-quality and uniform monolayer graphene has been synthesized on the Cu foil. The studies reveal that the density of bilayer graphene regions decreases with increasing the growth time; when the growth time increases to 120 min, the formation of bilayer regions is effectively prevented. The corresponding growth mechanism was discussed. Further, the electrical studies reveal that by preventing the formation of bilayer regions, the mobility of graphene not only obviously increases, but also has a narrow distribution, indicating that the as-synthesized monolayer graphene has high quality and uniformity. We expect that this work is beneficial for not only potential applications, but also the fundamental understanding of the growth mechanism for graphene on Cu surface.