Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 102: Quantum dots and wires: Transport
HL 102.1: Vortrag
Freitag, 15. März 2013, 11:15–11:30, H13
Momentum matching in magnetotunneling spectrocopy on quantum dots coupled to a two-dimensional electron gas — •D. Zhou1, A. Beckel1, B. Marquardt1, A. D. Wieck2, D. Reuter2, M. Geller1, and A. Lorke1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Germany — 2Chair for Applied Solid State Physics, Ruhr-Universität Bochum, Germany
We present results from magnetotunneling spectroscopy of self-assembled InAs QDs, weakly coupled to a 2DEG by a GaAs/AlGaAs tunneling barrier. The QDs are embedded in a heterostructure field-effect-transistor using the 2DEG as reservoir as well as detector. A magnetic field applied in the plane of the 2DEG is used to shift the alignment of the wave functions of the two systems in momentum-space. A time-resolved measurement technique is employed to directly determine the tunneling rates as a function of the magnetic field [1].
We find a strong suppression of the tunneling current by almost two orders of magnitude for fields up to 12 T. However, we find an enhancement in tunneling rates for small magnetic fields (<4 T). Comparison between the calculated and measured tunneling probabilities allows us to obtain detailed information on the QD states, such as size and anisotropy of the wave functions. We conclude that resonant tunneling between the dots and the 2DEG is affected by a nonvanishing momentum component perpendicular to the tunneling current even without an applied magnetic field, i. e. a momentum mismatch that significantly affects the tunneling probability.
[1] A. Beckel et al., Appl. Phys. Lett. 100, 232110 (2012).