Growth of graphene monolayer by “internal solid-state carbon source”: Electronic structure, morphology and Au intercalation

Abstract

Synthesis of a graphene monolayer atop Ni(111) film deposited on HOPG using method of “internal solid-state carbon source” due to low-temperature segregation of carbon atoms through Ni film from the Ni/HOPG interface was studied by core level and valence band photoelectron spectroscopy. The atomic structure and morphology were studied by STM. It was established that the synthesis of graphene occurs via a stage of transformation from the surface carbide phase (with stoichiometry Ni2C) as a result of the surface carbide decomposition. We consider that such transformation is a necessary stage of the graphene synthesis. We have shown that the method of “solid-state carbon source” indeed results in a graphene monolayer formation on top of Ni film. A graphene monolayer begins to form even under annealing at 180°C. Formation of practically full graphene covering with well-ordered structure takes place even at temperature of 260–270°C. The formed graphene is strongly coupled to the Ni substrate. STM images show formation of well-ordered atomic hexagonal surface structure characteristic for graphene monolayer. Intercalation of Au atoms leads to formation of the p(9×9) superstructure and blocks strong coupling. It testifies that the main part of the surface is covered by epitaxial graphene on Ni.