Ballistic transport of graphene pnp junctions with embedded local gates

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...

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Bibliographic Details
Published inNanotechnology Vol. 22; no. 41; pp. 415203 - 1-8
Main Authors Nam, Seung-Geol, Ki, Dong-Keun, Park, Jong Wan, Kim, Youngwook, Kim, Jun Sung, Lee, Hu-Jong
Format Journal Article
LanguageEnglish
Published England IOP Publishing 14.10.2011
Subjects
Carrier density
Carrier transport
Devices
Electric fields
Electrical junctions
Gates
Graphene
Transport
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Summary: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.
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ISSN:0957-4484
1361-6528
DOI:10.1088/0957-4484/22/41/415203