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HL: Fachverband Halbleiterphysik
HL 3: Graphene: THz, NIR and transport properties (with O/TT)
HL 3.7: Vortrag
Montag, 16. März 2015, 11:00–11:15, ER 270
Ballistic transport in graphene antidot arrays — •Andreas Sandner1, Tobias Preis1, Christian Schell1, Paula Giudici1, Kenji Watanabe2, Takashi Taniguchi2, Dieter Weiss1, and Jonathan Eroms1 — 1Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany — 2National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
We report on the observation of antidot peaks in ρxx in monolayer-graphene (MLG), encapsulated between hexagonal boron nitride (hBN). The hBN-MLG-hBN heterostructures were fabricated with a dry transfer pick-up technique; subsequently mesas were etched in Hall bar geometry and contacted with 1-dimensional side contacts. The periodic antidot lattice was defined in a following step by additional electron-beam lithography and reactive ion etching.
We performed measurements on stacks with different antidot lattice periods down to 100 nm. Several peaks in magnetoresistance can be identified and assigned to orbits around one and several antidots. This proves ballistic transport in our graphene heterostructures, in spite of the critical etching step for small lattice periods. We show measurements at different temperatures and can study antidots peaks down to very low carrier densities (n = 2 · 1011 cm−2) and magnetic fields (B = 0.5 T). At higher magnetic fields, well defined quantum Hall plateaus with filling factors down to ν=1 are observed, even at an antidot period of 100 nm.