Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 71: Poster Session: Graphene / Topological Insulators / Interfaces and Surfaces
HL 71.9: Poster
Mittwoch, 28. März 2012, 16:00–19:00, Poster D
Modulating Charge Carrier Concentration using Patterned Top Gates in Graphene Structures — •Franz-Xaver Schrettenbrunner, Dominik Koch, Dieter Weiss, and Jonathan Eroms — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany
We report on the fabrication and the measurements of graphene single layers with structured top gates. Starting from exfoliated graphene on SiO2 surfaces, a thin Al2O3 top gate dielectric was fabricated by atomic layer deposition (ALD). Subsequently a top gate electrode consisting of an array of lateral stripes with periodicities down to 100 nm was fabricated by electron beam lithography (EBL). The interplay of both patterned top- and extended back gate allows to tune type and concentration of charge carriers as well as the modulation strength. Different configurations like n+nn+, npn or p+pp+ can be realized. For npn configuration in single layer graphene, magnetotransport measurements show an unusual linear increase and additional dips in the magnetoresistance. Furthermore, we obtain quantum Hall states corresponding to locally modulated filling factors achieved by tuning the patterned top gate.