Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 16: Microcavities

HL 16.6: Vortrag

Montag, 14. März 2011, 16:00–16:15, FOE Anorg

In-plane manipulation of quantum dots by electric fields — •Johannes Beetz, Caroline Kistner, Stephan Reitzenstein, Christian Schneider, Sven Höfling, Martin Kamp, and Alfred Forchel — Universität Würzburg, Technische Physik, Am Hubland, 97074 Würzburg

Devices for applying vertical electric fields to quantum dots (QDs) are usually fabricated by conventional measures of lithography --- e.g. electron beam lithography --- using a pn-type heterostructure. The creation of lateral electrodes is even much more challenging, especially if they need to be applied to the active region of microcavites. This is of special interest since it is impossible to influence the in-plane electronic structure of self-assembled QDs with a vertical electric field. To generate the field inside the cavity layer of a micropillar, its sidewalls have to be provided with two diametrically opposed electric connections on the level of the cavity. In order to achieve this, we exploited focused ion beam induced deposition to define contacts on the micropillar's steep sidewalls. We optimized deposition parameters and contact architecture to preserve the cavity's Q-factor while achieving an effective coupling of the electric field into the cavity for minimized leakage currents. To evaluate the effect of the lateral field we examined the spectral emission of QDs located inside the cavity. We demonstrate the manipulation of the emission energy by the quantum confined Stark-effect with tuning ranges up to 0.1 meV. Moreover, first studies show a reduction of the exciton fine structure splitting, which is interesting for the generation of entangled photons.