Previous studies have shown that monolayer graphene films can be grown on Cu substrates by the catalytic decomposition of various carbon containing molecules. These films are typically grown on poly-crystalline Cu foils, which have a tendency to recrystallize into a {100} texture during the growth procedure. Since graphene crystallizes in a hexagonal lattice and the {100} surface of a face centered cubic lattice has a square symmetry, this is expected to result in multi-domain graphene growth. Because the Cu(111) surface has hexagonal symmetry and a lattice mismatch of 3.7% with graphene, growth on this surface termination has potential for producing films with a lower defect density.

There have been relatively few studies of graphene growth on single crystal Cu substrates, owing to the fact that hydrocarbon source pressures in the range of 100 millitorr are needed, which is incompatible with most UHV systems. In this study, graphene films were grown on Cu(111) substrates by first preparing the clean surface in UHV by sputtering with inert gas ions followed by annealing. The sample was then transferred to a conventional tube furnace where the graphene film was grown by annealing in forming gas to reduce the surface oxide, followed by annealing in ethylene to produce the graphene film.

The growth morphology of the graphene overlayer was characterized using low energy electron microscopy (LEEM) and low energy electron diffraction (LEED). The LEEM shows a mesa-like surface texture with relatively flat terraces covered with graphene and valleys between the terraces with low carbon coverage. Micro-Raman spectroscopy of the terrace regions produces a signal characteristic of a well-ordered graphene overlayer, whereas the Raman signal in the valleys is much weaker and shows a distinct D-peak. The typical lateral dimension of the terraces was ~10 μm. Micro-LEED performed on the terrace sites shows a sharp Moiré pattern. Conventional LEED, which probes a lateral area of ~1 mm, shows a ring structure with increased intensity in the six high symmetry directions of the Cu(111) substrate lattice. This indicates that for this growth procedure there is a quasi-epitaxial relationship between the graphene overlayer and the Cu(111) substrate with rotational disorder of the graphene from mesa to mesa. Synchrotron-based angle-resolved ultraviolet photoelectron spectroscopy (ARUPS) measurements have been performed to probe the electronic band structure of the graphene overlayer. A linear dispersion has been measured in the K direction with the Dirac point located near the Fermi level.