title: Ballistic transport of graphene pnp junctions with embedded local gates.
abstract: We fabricated graphene pnp devices, by embedding pre-defined local gates in an oxidized surface layer of a silicon substrate. With neither deposition of dielectric material on the graphene nor electron-beam irradiation, we obtained high-quality graphene pnp devices without degradation of the carrier mobility even in the local-gate region. The corresponding increased mean free path leads to the observation of ballistic and phase-coherent transport across a local gate 130 nm wide, which is about an order of magnitude wider than reported previously. Furthermore, in our scheme, we demonstrated independent control of the carrier density in the local-gate region, with a conductance map very much distinct from those of top-gated devices. This was caused by the electric field arising from the global back gate being strongly screened by the embedded local gate. Our scheme allows the realization of ideal multipolar graphene junctions with ballistic carrier transport.
authors.affiliation: Department of Physics, Pohang University of Science and Technology, Pohang, Republic of Korea.
authors.forename: Seung-Geol
authors.initials: SG
authors.lastname: Nam
authors.forename: Dong-Keun
authors.initials: DK
authors.lastname: Ki
authors.forename: Jong Wan
authors.initials: JW
authors.lastname: Park
authors.forename: Youngwook
authors.initials: Y
authors.lastname: Kim
authors.forename: Jun Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Hu-Jong
authors.initials: HJ
authors.lastname: Lee