Dresden 2011 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 4: Carbon: Diamond, Nanotubes, and Graphene
HL 4.10: Vortrag
Montag, 14. März 2011, 12:45–13:00, POT 251
Excited state spectroscopy on a bilayer graphene double quantum dot — •Christian Volk1,2, Stefan Fringes1, Bernat Terres1,2, Jan Dauber1, Stephan Engels1, Stefan Trellenkamp2, Uwe Wichmann1, and Christoph Stampfer1,2 — 1JARA-FIT and II. Institute of Physics B, RWTH Aachen, 52074 Aachen, Germany — 2Institute for Bio- and Nanosystems, Forschungszentrum Jülich, 52425 Jülich, Germany
Graphene double quantum dots are promising candidates for future spin-based quantum information applications. Here, we present tunneling spectroscopy experiments on a bilayer graphene double quantum dot device which can be tuned by five all-graphene lateral gates. The device has been prepared by exfoliation of natural bulk graphite, electron beam lithography and reactive ion etching. The diameter of the quantum dots are roughly 60 nm and the constrictions acting as tunneling barriers are 30 nm in width. Low noise charge stability measurements have been carried out in order to determine the gate lever arms and the addition energies of the two coupled quantum dots. Periodically ordered triple points of high conductance are present on a wide energy range as well as faint co-tunneling lines and excited states inside the triple points. We obtain addition energies of 18 and 23 meV respectively for the two dots. High resolution measurements on individual triple points allow us to resolve the energy spectra of excited states (level spacing 1.8 meV) and the interdot coupling energy (on the order of 2-4 meV).