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HL: Fachverband Halbleiterphysik

HL 44: Poster Session I

HL 44.15: Poster

Dienstag, 15. März 2011, 18:00–21:00, P3

Fabrication of top gates with ALD deposited Al₂O₃ on graphene structures — •Franz-Xaver Schrettenbrunner, Dieter Weiss, and Jonathan Eroms — Institut für Experimentelle und Angewandte Physik, Universtität Regensburg, 93040 Regensburg

We report the fabrication and transport measurements of top gated graphene devices. The insulating Al₂O₃ top gate was realized using atomic layer deposition. Usually, a seed layer (e.g. oxidized aluminum, NO₂/TMA process, etc.) has to be grown in order to achieve uniform oxide layers with low impurities. Previously, we have shown that a 100^∘C TMA/H₂O-process with low purge times of five seconds creates a stable top gate dielectric on graphene resulting in strong n-doping of the sample (impurity carrier density: n_ind=5.2·10¹²cm⁻²). Now this process was improved by growing 10nm Al₂O₃ at 100^∘C as a seed layer on which further material was deposited while heating the ALD reaction chamber up to 225^∘C. This "in-situ" annealing step forms a stable gate dielectric on our graphene structures with impurity carrier density n_ind=3.6·10¹¹cm⁻².