Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 71: Poster Session: Graphene / Topological Insulators / Interfaces and Surfaces
HL 71.3: Poster
Mittwoch, 28. März 2012, 16:00–19:00, Poster D
Influence of structural properties on ballistic transport in nanoscale epitaxial graphene cross junctions — •Epaminondas Karaissaridis1, Sonja Weingart1, Claudia Bock1, Ulrich Kunze1, Florian Speck2, and Thomas Seyller2 — 1Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum — 2Technische Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg
We have investigated the influence of important material and device properties on ballistic transport in conventionally grown [1] and additionally hydrogen intercalated [2] epitaxial graphene cross junctions. Our studies comprise a) magneto-transport in 2D Hall bars, b) temperature- and magnetic-field-dependent bend resistance of unaligned and step edge-aligned 1D orthogonal cross junctions and c) the influence of the cross junctions’ lead width on ballistic transport. We found that ballistic transport is highly sensitive to scattering at the silicon carbide step edges [3]. A suppression of ballistic transport is also observed when the lead width of the cross junctions is reduced from 50 to 30 nm. Furthermore, in a 50 nm wide 1D device prepared on quasi-freestanding graphene we observe a gradual transition from the ballistic to the diffusive transport regime when temperature is increased from 4.2 K to 30 K, although the 2D devices show a temperature-independent mean free path. Both results demonstrate that the influence of different scattering mechanisms must be studied in detail.
[1] K.V. Emtsev, et al., Nature Mater. 8, 203 (2009).
[2] F. Speck, et al., Mat. Sci. Forum 645-648, 629 (2010).
[3] S. Weingart, et al., Appl. Phys. Lett. 95, 262101 (2009).