[Zurück]

J. Güttinger, C Stampfer, F. Libisch, T. Frey, J. Burgdörfer, T. Ihn, K. Ensslin:
"Graphene quantum dots in magnetic fields";
Poster: Graphene week 2009, Obergurgl; 02.03.2009 - 07.03.2009.

We report transport measurements on an etched graphene nanoribbon. It is shown that two distinct voltage scales can be experimentally extracted that characterize the parameter region of suppressed
conductance at low charge densitiy in the ribbon. Finite source-drain voltage measurements in narrow ranges of voltages applied to local in-plane gates and the back gate reveal the presence of
localized states characterized by a source-drain voltage scale related to a charging energy of 10meV. Sweeps of the back gate voltage over a large range allow to extract a back gate voltage scale which is likely to be characteristic mainly for the disorder potential present in the ribbon. The lever arms of gates vary for different localized states by up to 30% indicating their spread in position along the ribbon. A single-electron transistor situated close to the nanoribbon is used to prove the addition of individual electrons to the localized states experimentally. We discuss the relation of the two experimental voltage scales to the charging energy, the energy gap created by the lateral confinement, and the magnitude of the disorder potential in the ribbon which is estimated to be of the
order of 100 meV.

graphene, quantum dots