  We report the realization of top-gated graphene nanoribbon field effect
transistors (GNRFETs) of ~10 nm width on large-area epitaxial graphene
exhibiting the opening of a band gap of ~0.14 eV. Contrary to prior
observations of disordered transport and severe edge-roughness effects of GNRs,
the experimental results presented here clearly show that the transport
mechanism in carefully fabricated GNRFETs is conventional band-transport at
room temperature, and inter-band tunneling at low temperature. The entire space
of temperature, size, and geometry dependent transport properties and
electrostatics of the GNRFETs are explained by a conventional thermionic
emission and tunneling current model. Our combined experimental and modeling
work proves that carefully fabricated narrow GNRs behave as conventional
semiconductors, and remain potential candidates for electronic switching
devices.
