▎ 摘　　要

Synthesis of graphene on Ni/Cu bilayer substrate by ion implantation is sensitive to the quality of the Ni/Cu substrate. In this work, different pretreatments of Cu foils were implemented to elucidate the role of Cu pretreatment on graphene synthesis. Four types of pretreatments including polishing, annealing at 950 degrees C, annealing at 1000 degrees C, and annealing at 1050 degrees C were conducted prior to the growth of the Ni coating layer. Four different Ni/Cu substrates were implanted by carbon ions and annealed to obtain monolayer graphene. It shows that the impurity particles emerging on the Cu foils annealed at 1000 degrees C and 1050 degrees C affect the crystalline quality of the synthesized graphene. In addition, the increase in roughness due to the polishing process induces non-uniformity of the obtained graphene. Overall, annealing at 950 degrees C is proven to be the proper pretreatment for Cu foil, and the corresponding graphene film has excellent crystalline quality and uniformity compared to those obtained on the substrates with other pretreatments.