Berlin 2012 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 69: Quantum Dots and Wires: Transport Properties II (mainly Quantum Dots)
HL 69.4: Talk
Wednesday, March 28, 2012, 18:00–18:15, EW 203
The influence of charged quantum dots on the transport properties of a two dimensional system — •Simon Wisotzki1, Andreas Beckel1, Bastian Marquardt1, Martin Geller1, Tobias Nowozin2, Andreas Marent2, Dieter Bimberg2, and Axel Lorke1 — 1Faculty of Physics and CeNIDE, University of Duisburg-Essen, Lotharstraße 1, 47057 Duisburg, Germany — 2Institute for Solid State Physics, Technische Universitaet Berlin, Hardenbergstraße 36, 10623 Berlin, Germany
A crucial point for electrically controlled quantum and memory devices, based on self-assembled quantum dots (QDs), is the read-out of their charge/spin state. Coupling the zero-dimensional QDs to a two-dimensional electron or hole gas (2DEG, 2DHG) by Coulomb interaction enables a non-destructive read-out by a measurement of the conductivity of the two-dimensional system. A time-resolved transport spectroscopy technique was used to separately determine the contributions of the change in charge carrier concentration and mobility to the overall change of conductivity of a 2DEG while charging the QDs with electrons. Here, the influence of individual holes stored inside these QDs on the transport properties of the 2DHG was investigated. We were able to separately determine the contribution of charged QDs as Coulomb scatterers and their influence on the charge carrier density in the 2DHG. Our results enable a deeper understanding of the interfacing between QDs and a 2DEG/2DHG, which is essential for the development of QD based memories, quantum devices or velocity modulated transistors (VMT).