Regensburg 2010 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 46: Quantum Dots and Wires: Transport
HL 46.7: Talk
Wednesday, March 24, 2010, 15:30–15:45, H17
Spectroscopy of non-equilibrium charging states of self-assembled quantum dots — •Bastian Marquardt1, Martin Geller1, Axel Lorke1, Dirk Reuter2, and Andreas Wieck2 — 1Experimental Physics and CeNIDE, University Duisburg-Essen — 2Chair of Applied Physics, Ruhr University Bochum
Electron-electron (or hole-hole) interaction in confined electron systems like self-assembled quantum dots (QD) has been a topic of continuing interest for roughly 15 years [1, 2]. The Coulomb repulsion between the charge carriers has dramatic effects on the conductance through a QD, as evidenced, by the so called Coulomb blockade. However, measurements of the QD states without the influence of Coulomb repulsion has not been studied yet. Using, for instance, pulsed time-resolved measurement to prepare a non-equilibrium situation between the QD states and the chemical potential enables us to study dot states in transport measurements without Coulomb blockade. We study charge tunneling of self-assembled InAs QDs through large tunneling barriers resulting in charging times between 1 ms and 100 s. These long times allow us to adjust the chemical potential on time scales much faster than the average charge tunneling time of the dots. This way, non-equilibrium situations can be realized where the chemical potential in the reservoir is higher than all states in the dot. On the basis of the measured transients non-equilibrium dot states can be identified for different applied magnetic fields.
[1] D. Bimberg et al., Quantum Dot Heterostructures (Wiley, Chichester, 1998). [2] D. Reuter et al., Phys. Rev. Lett. 94, 026808 (2005).