Copper-Vapor-Assisted Growth and Defect-Healing of Graphene on Copper Surfaces

Although there is significant progress in the chemical vapor deposition (CVD) of graphene on Cu surfaces, the industrial application of graphene is not realized yet. One of the most critical obstacles that limit the commercialization of graphene is that CVD graphene contains too many vacancies or sp(3)-type defects. Therefore, further investigation of the growth mechanism is still required to control the defects of graphene. During the growth of graphene, sublimation of the Cu catalyst to produce Cu vapor occurs inevitably because the process temperature is close to the melting point of Cu. However, to date few studies have investigated the effects of Cu vapor on graphene growth. In this study, how the Cu vapor produced by sublimation affects the chemical vapor deposition of graphene on Cu surfaces is investigated. It is found that the presence of Cu vapor enlarges the graphene grains and enhances the efficiency of the defect-healing of graphene by CH4. It is elucidated that these effects are due to the removal by Cu vapor of carbon adatoms from the Cu surface and oxygen-functionalized carbons from graphene. Finally, these insights are used to develop a method for the synthesis of uniform and high-quality graphene.