Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 5: Quantenpunkte und -dr
ähte: Transporteigenschaften I
HL 5.10: Vortrag
Montag, 24. März 2003, 12:45–13:00, POT/81
Parallel Quantum Dots with Tunable Coupling — •Maximilian C. Rogge1, C. Fühner1, U. F. Keyser1, R. J. Haug1, W. Wegscheider2, and M. Bichler3 — 1Institut für Festkörperphysik, Universität Hannover — 2Angewandte und Experimentelle Physik, Universität Regensburg — 3Walter Schottky Institut, TU München
We have fabricated a parallel double quantum dot based on GaAs/AlGaAs heterostructures by combining Atomic Force Microscope (AFM) lithography and electron beam lithography. In a first step the AFM lithography is used to realize a large Single-Electron Tunneling Transistor (SET) by Local Anodic Oxidation (LAO). Then a narrow metallic top gate is patternd on top of this SET by electron beam lithography. By application of a negative voltage to the top gate electrode the large single quantum dot can be split into two smaller parallel dots. In this way we control the coupling between both dots to form an artificial molecule or even two separat quantum dots. In a regime where both quantum dots show Coulomb-blockade, we observe the typical hexagonal honeycomb structure in gate-gate measurements which indicates two quantum dots with capacitive coupling. We extract the capacitance between both dots from the shape of these hexagons.