Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 15: C/diamond I

HL 15.7: Talk

Tuesday, March 24, 2009, 11:00–11:15, POT 51

Weak Localization and Transport Gap in Graphene Antidot Lattices — •Jonathan Eroms and Dieter Weiss — Institut für Experimentelle und Angewandte Physik, Universität Regensburg

We have performed transport experiments in antidot lattices in single layer graphene. After mechanical exfoliation from natural graphite, suitable single layer flakes were patterned into antidot lattices using electron beam lithography and plasma etching. The lattice periods varied between 90 nm and 400 nm.

When the lattice period is reduced, the quantum Hall effect gradually disappears owing to the geometrical condition that a cyclotron orbit has to fit through the constrictions between the antidots. Samples with narrow channels between the antidots can be regarded as a network of graphene nanoribbons and correspondingly show a transport gap of a few mV at low temperatures.

In the magnetotransport curves we observe a pronounced weak localization effect. The strong visibility is due to intervalley scattering at the antidot edges. By a careful examination of the temperature and geometry dependence we conclude that our short-period antidot lattices are best described as an array of phase-coherent cavities.