Epitaxial growth of graphene on Ir(111) by liquid precursor deposition

The epitaxial growth of graphene on the surface of an Ir/YSZ/Si(111) multilayer substrate via the deposition of a liquid carbon precursor (acetone) was investigated by x-ray photoelectron spectroscopy, x-ray photoelectron diffraction, low-energy electron diffraction (LEED), and Fermi surface mapping. It is shown that the onset of graphene formation starts in a low temperature range around 600 K and that subsequent annealing up to 1000 K finally results in well-ordered graphene monolayers. Comparison of temperature-dependent LEED data with model calculations suggests that the growth of graphene takes place via a backbonelike growth by the formation of a hexagonal network connecting the hcp and fcc configuration sites within the similar to 10 x 10/9 x 9 supercell. In LEED, the low intensities of the superstructure related satellite spots give evidence for only small corrugations of the graphene layer due to weak interaction with the Ir(111) surface, making graphene on Ir(111) similar to free-standing graphene with the Fermi surface providing distinct spots at the K points.