Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 22: Graphene 2 (Joint Session with TT)
HL 22.7: Vortrag
Dienstag, 23. März 2010, 11:15–11:30, H21
Top and bottom gated field effect devices on epitaxial graphene — •Daniel Waldmann1, Johannes Jobst1, Florian Speck2, Thomas Seyller2 und Heiko B. Weber1 — 1Lehrstuhl für Angewandte Physik, Universtität Erlangen-Nürnberg, Erlangen, Germany — 2Lehrstuhl für Technische Physik, Universtität Erlangen-Nürnberg, Erlangen, Germany
We fabricate high-quality epitaxial graphene devices (Hall bars) for electrical transport measurements. In order to tune the charge density in the graphene layer, we developed different gating schemes (top gate and bottom gate). As a top gate we either used an electrochemical gate employing an ionic liquid or a solid state gate using aluminium oxide. A bottom gate has the advantage of leaving the graphene layer open. We have opted for an implanted conducting layer buried in the semi-insulating silicon carbide substrate. Hence, the SiC above the implanted gate serves both as substrate and gate dielectric. We present experimental data from low temperatures to room temperature which cover a broad range of charge densities including the electron hole transition at the Dirac point. Advantages and limitations of each method are discussed.