Condensed-Matter Physics & Materials Science Seminar

Graphene is a promising candidate for carbon-based devices due to its exceptional electronic properties at low carrier densities. These properties originate from the linear energy dispersion and particle-hole symmetry in the vicinity of the Dirac point. Thus, the nearly neutral
graphene is desired for carbon-based electronics. A prerequisite for large scale applications is the epitaxial graphene, preferably of high structural quality and electronically only weakly perturbed by the substrate, so that it can be further manipulated for electronic devices.

We have prepared graphene on Ir(111) in exceptional structural quality and have studied it by angle-resolved photoelectron spectroscopy. It is found to interact only weakly with Ir(111) resulting in an intact Dirac cone with a Dirac point shifted slightly above the Fermi level.
Moreover, the mismatch between graphene and Ir(111) surface lattice implies a superperiodic potential which gives rise to Dirac cone replicas and the opening of the corresponding band gap. Based on our findings, Ir appears to be well suited for electronic contacts to graphene. Graphene on Ir(111) is also a specifically simple epitaxial graphene system which is potentially of interest for further fundamental investigations.