Graphene on Ir(111) characterized by angle-resolved photoemission

Angle-resolved photoelectron spectroscopy (ARPES) is extensively used to characterize the dependence of the electronic structure of graphene on Ir(111) on the preparation process. ARPES findings reveal that temperature-programmed growth alone or in combination with chemical vapor deposition leads to graphene displaying sharp electronic bands. The photoemission intensity of the Dirac cone is monitored as a function of the increasing graphene area. Electronic features of the moire superstructure present in the system, namely, minigaps and replica bands are examined and used as robust features to evaluate graphene uniformity. The overall dispersion of the pi band is analyzed. Finally, by the variation of photon energy, relative changes of the pi and sigma band intensities are demonstrated.