The potential for electronics based on graphene, a single layer of sp2-bonded carbon atoms, rests on the ability to fabricate graphene into useful devices. Graphene grown epitaxially on SiC substrates offers an avenue for carbon-based electronics allowing for large area fabrication of carbon structures, patterning with standard lithographic procedures, and potential integration with current Si technology 1,2. A major obstacle to this approach is a lack of understanding of the role that the SiC interface plays in determining the electronic properties and charge transport in the graphene/SiC system. In this letter, we image the interface structure beneath the first graphene layer on the SiC substrate using scanning tunneling microscopy (STM) at a series of bias voltages. Such imaging is possible because the first layer of graphene becomes semi-transparent at energies of 1 eV above or below the Fermi-energy, yielding images of the SiC interface. Our analysis of calculations based on density functional theory shows how this transparency arises from the electronic structure of a graphene layer on the SiC substrate.
Citation: Physical Review B (Condensed Matter and Materials Physics)
Pub Type: Journals