Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.10: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Transport measurements in width modulated graphene nanoribbons — •Silvia Schmidmeier, Dieter Weiss, and Jonathan Eroms — Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany

We investigate electronic transport both in graphene and graphene nanoribbons (GNRs). The lateral confinement of the charge carriers in the quasi one-dimensional ribbons creates an energy gap near the charge neutrality point, where the gap depends on the width of the GNR. Here we are using this width dependence to create a potential modulation along the nanoribbon. To this end, the ribbon width is varied periodically, which we expect to affect the electronic transport in an interesting way. GNRs with different width, flat as well as modulated ribbons, were fabricated by electron beam lithography and plasma etching techniques. The devices are fully tunable by two graphene sidegates and a backgate. Here we present the first measurements on those GNRs. In order to verify the single-layer character we performed quantum Hall measurements and found the characteristic half-integer quantization. By examining the differential I-V characteristics of the GNRs a transport gap is clearly observed at the Dirac point. We also measured the magnetoconductance in a perpendicular magnetic field for different temperatures. At low magnetic fields weak localization is clearly visible, therefore the phase coherence length can be determined by 1D weak localization theory. Additionally it was extracted in an independent way from the amplitude of the universal conductance fluctuations.