Dresden 2003 – wissenschaftliches Programm
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SYQD: Quantum decoherence in solid state physics
SYQD 2: Quantum Decoherence in Solid State Physics II
SYQD 2.4: Vortrag
Dienstag, 25. März 2003, 18:15–18:30, HSZ/01
Exciton Dephasing in InGaAs Quantum Dots — •W. Langbein1, P. Borri1, S. Schneider1, U. Woggon1, R. L. Sellin2, D. Ouyang2, and D. Bimberg2 — 1Exp. Physik IIb, Universität Dortmund, Otto-Hahn-Str. 4, 44221 Dortmund — 2Institut für Festkörperphysik TU, Hardenbergstrasse 36, D-10623 Berlin, Germany
We measure the dephasing time of ground-state excitonic transitions in InGaAs quantum dots in the temperature range from 7 K to 300 K. At 7 K, a long dephasing time of 630 picoseconds is observed, corresponding to 2 µeV homogeneous linewidth [1]. Between 7 K and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian homogeneous line shape with a narrow zero-phonon line and a broad band. Such a line shape is characteristic for the acoustic-phonon interactions of strongly localized excitons [2]. Electrical injection of carriers into the barrier region results in a pure dephasing of the excitonic transitions [3]. Once the injected carriers fill the electronic ground state, the biexciton to exciton transition is probed and a correlation of the exciton and biexciton phonon scattering mechanisms is found. Additional filling of the excited states creates multiexcitons that show a fast dephasing due to population relaxation.
[1] P. Borri et al., Phys. Rev. Lett. 87, 157401 (2001)
[2] L. Besombes et al., Phys. Rev. B 63, 155307 (2001)
[3] P. Borri et al., Phys. Rev. Lett. 89, 187401 (2002)