Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 7: Quantum dots: Optical properties I
HL 7.10: Vortrag
Montag, 23. März 2009, 16:15–16:30, BEY 118
Independent Tuning of Different Few Particle States in Single InGaAs Quantum Dots Using Lateral Electric Fields — •Malte Frederik Huck, Michael Kaniber, Max Bichler, and Jonathan James Finley — Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching
We present studies of the optical emission from single quantum dots (QDs) subject to electric field perturbations applied in the plane of the QDs. The samples consist of low density (∼ 5µ m−2) self-assembled InGaAs QDs grown by molecular beam epitaxy embedded in a GaAs slab. Metal split gate contacts with a 2µm separation were established on top of the sample allowing the optical properties of the QDs to be probed with static electric fields up to 50 kV/cm. Photoluminescence and photocurrent measurements were performed to identify the different charge configurations of the QD and to study the influence of the external electric fields on the corresponding few particle states. We observe pronounced energy shifts of individual emission lines up to |Δ E|=4meV, due to the quantum confined Stark effect. Surprisingly, different states from the same QD are found to exhibit characteristic red- and blue-shifts. This behaviour is attributed to the interplay between the field induced polarization of the state, producing the Stark shift, and the change of the Coulomb interaction and correlation effects. The observed shift rates are in good agreement with theoretical predictions. Our results show that single charge neutral exciton and biexciton transitions can be tuned into resonance, providing strong potential to realize a source of energy-time entangled photon pairs.