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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 17: 2D Materials I: Electronic Structure, Excitations, etc. (joint session O/CPP/HL)
CPP 17.3: Vortrag
Montag, 16. März 2020, 11:15–11:30, WIL C107
The edge morphology and electronic properties of ballistic sidewall zig-zag graphene nanoribbons on SiC (0001) — •T.T.Nhung Nguyen1, H. Karakachian2, J. Aprojanz1, U. Starke2, A. Zakharov3, C. Polley3, and C. Tegenkamp1 — 1TU Chemnitz, Germany — 2Max Planck Institute, Germany — 3MAX IV Lab, Sweden
Epitaxial graphene nanoribbons grown on SiC(0001) mesa structures were shown to reveal ballistic transport at room temperature. The subsequent improvement of preparation parameters allows us to fabricate large scale zig-zag type ribbons with 40nm in widths with a pitch size down to 200 nm. We analyzed the electronic structure of the ribbons and their edges by ARPES and STM/STS. Indeed, ARPES reveals clearly the Dirac cone from the ribbon. The Fermi energy coincides with the Dirac point. This finding is corroborated by STS, revealing an elastic tunneling gap of around 130meV. STM shows that the zig-zag edge merges into the SiC substrate. Exactly at the position of this edge, a metallic state is seen at 0V. The gradual decrease of its intensity within 3nm comes along with a peak splitting. Moreover, the valence and conduction band states reveal close to the edge a larger gap of around 300 meV. We assign these findings to a hybridization of the zig-zag GNR edge with SiC. Furthermore, we propose that the ballistic transport is rather mediated by a 1D interface state rather than by a GNR edge state. The interface state mimics massive particles, which is consistent with the energy positions of electron transmission peaks found in GNR nanoconstrictions of various lengths.