Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.50: Poster
Donnerstag, 26. März 2009, 15:00–17:30, P2
Fine structure tuning in self-assembled (In,Ga)As quantum dots by uniaxial stress — •Klaus D. Jöns1, Robert Hafenbrak1, Sven M. Ulrich1, Lijuan Wang2, Armando Rastelli3, Oliver G. Schmidt3, and Peter Michler1 — 1Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart, Allmandring 3, 70569 Stuttgart, Germany — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany — 3Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, 01069 Dresden, Germany
Entangled photon pairs are an important prerequisite to implement e.g. quantum cryptography. The biexciton-exciton cascade in (In,Ga)As quantum dots (QDs) is a promising source of such quantum states. Still, intrinsic quantum dot fine structure splitting inhibits entanglement. Therefore, the fine structure splitting as a limiting factor has to be reduced using a post-growth technique. In our work we present fine structure tuning of self-assembled (In,Ga)As QDs by uniaxial stress. For this purpose we glued the sample tightly on a piezo actuator and applied tunable uniaxial stress along a crystal axis parallel to the sample surface. Our setup enables us to apply both tensile and compressive stress on the sample in a helium-flow cryostate so the confining potential can be tuned in two directions to achieve zero fine structure. The photoluminescence was detected by a high resolution setup using a Fabry-Pérot interferometer. Our results at 8K temperature show that the spectral emission of the QDs shifts by applying piezo voltage and that the fine structure splitting can be tuned considerably.