Controlled crossover of electron transport in graphene nanoconstriction: From Coulomb blockade to electron interference

The ability to control transport behaviors in nanostructure is crucial for usage as a fundamental research platform as well as a practical device. In this study, we report a gate-controlled crossover of electron transport behaviors using graphene nanoconstrictions as a platform. The observed transport properties span from Coulomb blockade-dominated single electron transmission to electron-wave interference-dominated quantum behavior. Such drastic modulation is achieved by utilizing a single back gate on a graphene nanoconstriction structure, where the size of nanostructure in the constriction and coupling strength of it to the electrodes can be tuned electrically. Our results indicate that electrostatic field by gate voltage upon the confined nanostructure defines both the size of the nanoconstriction as well as its interaction to electrodes. Increasing gate voltage raises Fermi level to cross the energy profile in the nanoconstriction, resulting in decreased energy barriers which affect the size of nanoconstriction and transmissivity of electrons. The gate-tunable nanoconstriction device can therefore become a potential platform to study quantum critical behaviors and enrich electronic and spintronic devices.