  We have developed the combination of an etching and deposition technique that
enables the fabrication of locally gated graphene nanostructures of arbitrary
design. Employing this method, we have fabricated graphene nanoconstrictions
with local tunable transmission and characterized their electronic properties.
An order of magnitude enhanced gate efficiency is achieved adopting the local
gate geometry with thin dielectric gate oxide. A complete turn off of the
device is demonstrated as a function of the local gate voltage. Such strong
suppression of device conductance was found to be due to both quantum
confinement and Coulomb blockade effects in the constricted graphene
nanostructures.
