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HL: Halbleiterphysik
HL 5: Quantenpunkte und -dr
ähte: Transporteigenschaften I
HL 5.2: Vortrag
Montag, 24. März 2003, 10:45–11:00, POT/81
Fano resonances in semiconductor quantum dots — •Claus Fühner1, U. F. Keyser1, M. Rogge1, R. J. Haug1, D. Reuter2, and A. D. Wieck2 — 1Institut für Festkörperphysik, Universität Hannover — 2Lehrstuhl für angewandte Festkörperphysik, Ruhr-Universität Bochum
We present electronic transport measurements on large split-gate single-electron tunneling transistors (SETs) based on GaAs/AlGaAs heterostructures. While investigations of the Coulomb-blockade and Kondo transport regimes are well established, only little attention has been paid to the Fano resonances observed at strong coupling and low charging energy in some SETs. Fano resonances stem from interference of a resonant transport channel (the quantum dot with well-known Coulomb resonances) with an additional non-resonant transport channel. They exhibit characteristic lineshapes determined by amplitudes and phases of the electronic wave function transmitted through the two contributing channels. In a regime of extremely strong coupling of the quantum dot to the leads, we observe tunable and well reproducible Fano resonances at the positions of 14 consecutive Coulomb peaks. We study the influence of finite bias voltage, temperature, and a perpendicular magnetic field on the resonance lineshape. From the resonance lineshapes, we extract information on the phase evolution of the non-resonant transport channel.