Preparation of bilayer graphene utilizing CuO as nucleation sites by CVD method

Graphene is an attractive 2D material for optoelectronics applications. However, due to the spontaneous nucleation characteristics of graphene growth on the metal substrates using chemical vapor deposition method, the polycrystalline graphene exhibited many crystal defects, leading to poor crystal quality. Properly controlling the density of nucleation sites is an important and necessary mean to increase the quality of graphene material. In this work, a new method to synthesize high-quality graphene on Cu substrate was reported by utilizing the CuO nanoparticles as nucleation sites. It was found that when annealing the copper substrate at 300 °C for 30 min with Ar:O 2 flow ratio of 64:1, the copper substrate showed the lowest roughness and the density of CuO nucleation sites after hydrogen etching (H 2 21 sccm at 1035 °C). Bilayer graphene with diagonal length of ~ 3 µm was successfully prepared centering on the CuO nucleation sites. This work supplied a new clue for high quality and monocrystalline graphene preparation.