Synthesis and electronic structure of graphene on a nickel film adsorbed on graphite

The formation of graphene on the surface of a nickel thin film on a highly oriented pyrolytic graphite substrate has been investigated using the photoelectron spectroscopy methods. It has been shown that the formation of graphene occurs through the phase of surface nickel carbide with the Ni$_2$C stoichiometry, which is formed already at a temperature of 180$^\circ$C. During the subsequent heating, the nickel carbide phase transforms into a graphene monolayer strongly bound to the surface. All the phase transitions have been thoroughly analyzed in terms of the fine structure of the photoelectron lines. The surface morphology has been examined using atomic force microscopy, and the obtained data have been presented. It has been especially emphasized that the advantage of the studied method of a “solid-state” source of carbon is the possibility of the formation of graphene at lower temperatures (at least no higher than 280$^\circ$C) as compared to the cracking of carbon-containing gases, which requires the temperature ranging from 400 to 500$^\circ$C.