Electronic Structures of Graphene on Ru(0001): Scanning Tunneling Spectroscopy Study

Graphene has inspired remarkable advances in nanotechnology due to its unusual electronic band structures represented by massless Dirac cones. Graphene can be epitaxially grown on metal surfaces by chemical vapor deposition method. Due to the lattice mismatch, epitaxial graphene grown on Ru(0001) shows hexagonal Moir\'e patterns with subatomic height variations. We studied local electronic structures of the epitaxial graphene using low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). Different spectra were observed at top, bridge, and hollow regions of the Moir\'e patterns. Observed STS data will be explained with structural models.