  We have demonstrated the fabrication of both armchair and zigzag epitaxial
graphene nanoribbon (GNR) devices on 4H-SiC using a polymer-assisted
sublimation growth method. The phenomenon of terrace step formation has
traditionally introduced the risk of GNR deformation along sidewalls, but a
polymer-assisted sublimation method helps mitigate this risk. Each type of 50
nm wide GNR is examined electrically and optically (armchair and zigzag), with
the latter method being a check on the quality of the GNR devices and the
former using alternating current to investigate resistance attenuation from
frequencies above 100 Hz. Rates of attenuation are determined for each type of
GNR device, revealing subtle suggested differences between armchair and zigzag
GNRs.
