Graphene has recently attracted a great deal of interest in both academia and industry because of its unique electronic and optical properties as well as its chemical, thermal, and mechanical properties. The superb characteristics of graphene make this material one of the most promising candidates for various applications, such as ultrafast electronic circuits and photodetectors, clean and renewable energy and rapid single-molecule DNA sequencing. The electronic properties of the graphene system rely heavily on the number of graphene layers and effects on the coupling with the underlying substrate. Graphene can be produced by mechanical exfoliation of graphite, solution approaches thermal decomposition of SiC, and chemical vapor deposition/segregation on catalytic metals. Despite significant progress in graphene synthesis, production with fine control over the thickness of the film remains a considerable challenge. Here, we report on the synthesis of nearly 100% coverage of single-layer graphene on a Ni(111) surface with carbon atoms diffused from a highly orientated pyrolytic graphite (HOPG) substrate. Our results demonstrate how fine control of thickness and structure can be achieved by optimization of equilibrium processes of carbon diffusion from HOPG, segregation from Ni, and carbon diffusion at a Ni surface. Our method represents a significant step toward the scalable synthesis of graphene films with high structural qualities and finely controlled thicknesses and toward realizing the unique properties of graphene.
Epitaxy growth of our system at a lower temperature (~650 ºC) produces uniform monolayer graphene in controlled modes of carbon diffusion from HOPG, solubility in Ni, and carbon diffusion at the Ni surface. The availability of such uniform thickness graphene will provide an interesting system for the exploration of relevant properties of non-mechanical exfoliated graphene and for practical large-scale applications. Our approach opens a new venue for guiding the graphene production process, as graphene films with high crystalline quality and uniform thickness are essential to realize unique electron transport for graphene-based technologies.