Regensburg 2019 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 14: Poster

DS 14.10: Poster

Dienstag, 2. April 2019, 17:00–20:00, Poster E

The microscopic structure of ballistic graphene nanoribbons — •Markus Gruschwitz, Thi Thuy Nhung Nguyen, Herbert Schletter, Steffen Schulze, and Christoph Tegenkamp — Institut für Physik, TU Chemnitz, Germany

Epitaxial graphene nanoribbons on SiC were shown to host ballistic transport channels, even under ambient conditions [1]. Thereby, the transport of these 40nm wide ribbons, which are grown via self-assembly on sidewalls of SiC(0001) mesa structures, depends crucially on atomistic details of the structure [2]. Here we present high resolution STM and TEM investigations done on such ribbons.

For ribbons along the [1100]-direction STM reveals a continuous graphene layer with a zig-zag edge structure. Thereby, the lower edge merges into the SiC(0001) terrace giving rise to hybridization and formation of an edge state. This growth mode is confirmed by S/TEM investigations. Cross sectional STEM reveals freestanding graphene separated from the facette by more than three times the distance of graphene on SiC(0001). Moreover, the EDX and EELS capabilities of the HRTEM were used to characterize the surface near areas in detail. Upon growth of graphene by desorption of silicon by high temperature annealing, the first 6H-SiC unit cell reveals sp²-hybridization coming along with Si deficiency. Compared to the facettes, it turns out that these residual imperfections in SiC are more frequent at terraces, which supports higher Si-evaporation rate at the mesas in order to grow selectively graphene nanoribbons. References: [1] J. Aprojanz et al., Nat. Comm. 9, 4426, (2018). [2] A.A Zakharov et al., arXiv:1809.10001