$Z\text{−}V$ scanning tunneling spectroscopy is used to probe the topology and electron scattering properties of the electronic interfaces of monolayer and bilayer graphenes, expitaxially grown on SiC(0001). The $dZ/dV$ spectra validate existing calculations of the interface topology and provide evidence for new electron scattering properties due to changes in the electronic character of the bonding. Two sharp boundaries are observed: between the vacuum and the graphene $\pi$ state lying above the graphene atom plane and a subsurface barrier between the carbon-rich layer and the bulk SiC.

• Received 16 June 2008

DOI:https://doi.org/10.1103/PhysRevB.78.041408