Scanning tunneling microscopy (STM) and spectroscopy (STS) is used to study the structural and electronic properties of bilayer epitaxial graphene on SiC(0001). Topographic images reveal that graphene conforms to the SiC interface roughness and is observed to be continuous across steps separating adjoining terraces. Bilayer epitaxial graphene is shown to be Bernal stacked as evidenced by bias dependent topographic imaging. STS maps of the differential conductance of bilayer graphene show that graphene lattice defects cause scattering of charge carriers near the Fermi level. An analysis of the scattering observed in the conductance maps allows the measurement of the energy-momentum dispersion relation within 100 meV of the Fermi level. In contrast to lattice defects, the disorder from the interface and surface steps below the graphene play a much lesser role in the scattering of charge carriers.
Citation: Journal of Vacuum Science and Technology A
Pub Type: Journals
graphene, scanning tunneling microscopy, scanning tunneling spectroscopy, silicon carbide