Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)
O 35.88: Poster
Dienstag, 12. März 2013, 18:15–21:45, Poster B1
Investigation of graphene contact resistivity on semi-insulating silicon carbide by Kelvin Probe Force Microscopy — •Felix Lüpke, Martin Wenderoth, Thomas Druga, and Rainer G. Ulbrich — IV. Physikalisches Institut, Georg-August Universität Göttingen, Germany
We present first Kelvin Probe Force Microscopy (KPFM) and simulation of the lateral charge transport across few-layer graphene on the semi-insulating 6H-SiC(0001) surface. After preparation of the SiC crystal using common methods [1], atomically flat graphene layers of up to few hundred nm in lateral dimension were observed. Gold electrodes were prepared on top of the graphene layer by thermal evaporation through a shadow mask. For transport measurements a lateral voltage was applied across the sample at the gold electrodes in addition to the usual alternating tip-sample voltage used for KPFM [2]. The potential measured by KPFM is an overlay of the local work function of the sample and the voltage drop across the graphene layer. By subtracting measurements of reverse lateral bias the voltage drop was extracted. We find an ohmic behavior of the contacted graphene layer and a graphene sheet resistance of 1 kΩ/sq. By comparing the experimental transport measurements with a resistance network simulation the contact resistivity between graphene and a gold electrode can be determined to <1×10−5 Ω/cm2.
[1] Forbeaux, I.; Themlin, J.-M.; Debever, J.-M. Phys. Rev. B, 1998, 58, 24 [2] Yan, L.; Punckt, C.; Aksay, I. A.; Mertin, W.; Bacher, G. Nano Lett., 2011, 11