  We theoretically study the effect of transverse electric potentials on the
transport properties of armchair graphene nanoribbons (AGNRs), formed by pairs
of asymme-tric gates placed along the side of the ribbon. Single pair and dual
pair configurations are considered. We also examine the effect of hollows
(spatial regions void of carbon atoms) in the AGNR channels. We find that the
use of hollowed AGNRs in the dual pair configuration allows for a significant
modulation of the transport gap, when the two pairs have opposite polarity of
gate bias. Furthermore, we show that for the dual-gate system, hollowed AGNR
channels exhibit the optimal ratio of ON-state to OFF-state conductance, due to
the smaller OFF-state conductance compared with spatially homogenous AGNR
channels. Our results indicate that transverse gate technology coupled with
careful engineering of hollow geometry may lead to possible applications in
graphene-based electronic devices.
