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Epitaxial Graphene’s Edge

Ming Ruan, Yike Hu, James Palmer, Tom Guo, John Hankinson, Rui Dong, Claire Berger, Walt de Heer School of Physics, Georgia Tech

The resistance of a graphene sidewall ribbon, about 300 nm long and 30 nm wide as imaged with an atomic force microscope (upper right) is measured by scanning a conducting tip over. The resistance is almost constant in the latter half of the ribbon, indicating ballistic transport.

The conductance of a sidewall ribbon, provided with a electrostatic gate, is measured as a function of the gate potential at temperature ranging from 4 K to 300 K. The conductance varies only moderately for all temperatures and gate voltages indicating that the graphene ribbon acts like a metallic quantum wire over a wide range of temperatures.

Epitaxial graphene nanoribbons readily grow on the sidewalls of steps etched on silicon carbide crystals. These sidewall ribbons are found to have very low resistances that are due to electrons that move along the ribbon edges. These electrons are particularly immune to scattering in contrast to other electrons in the ribbon. The residual resistance appears to be quantized implying that the transport is ballistic. This very important effect of epitaxial graphene sidewall ribbons allows them be used as quantum interconnects in future graphene nanodevices.