Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 104: Quantum Dots and Wires: Optical Properties V (mainly Indiviual Photons)

HL 104.7: Vortrag

Freitag, 30. März 2012, 13:15–13:30, EW 201

Growth and Analysis of Quantum Dots with highly reduced Fine Structure Splitting — •Julian Treu, Alexander Huggenberger, Christian Schneider, Alfred Forchel, Sven Höfling, and Martin Kamp — Technische Physik, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

Quantum key distribution for secure communication requires efficient sources of single or entangled photons. A possible source for entangled photons is the biexciton-exciton cascade in semiconductor quantum dots (QDs). In this case, the fine structure splitting (FSS) has to be less than the homogenous linewidth. For InGaAs/GaAs QDs grown on common (100) substrates it can be shown that piezoelectric fields reduce the symmetry and often a reduction of the FSS by post-growth annealing or the application of an electric/magnetic field is required. Therefore, QDs with an inherently vanishing FSS are highly desirable.

We have investigated the growth of self organized, low density quantum dots (QDs) on high index substrates like (111) GaAs where such a reduction of symmetry is not existent. Microphotoluminescence spectroscopy (µ PL) measurements reveal single QD lines in the range 850-900nm and linewidths below 100µ eV. The measured FSS <10µ eV is limited by the resolution of our setup.