Berlin 2008 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 6: Semiconductor Nanophotonics: Materials, Models, Devices - High Speed Photonics
DS 6.4: Vortrag
Montag, 25. Februar 2008, 10:45–11:00, H 2032
Relaxation oscillations in quantum dot lasers — •Ermin Malic1, Kathy Lüdge1, Moritz Bormann1, Philipp Hövel1, Matthias Kuntz2, Dieter Bimberg2, Andreas Knorr1, and Eckehard Schöll1 — 1Institut für Theoretische Physik, TU Berlin, Hardenbergstr. 36, 10623 Berlin, Germany — 2Institut für Festkörperphysik, TU Berlin
We present a theoretical simulation of the turn-on dynamics of electrically pumped InAs/GaAs quantum dot lasers. Our approach combines laser rate equations with microscopically calculated Coulomb scattering rates describing Auger transitions between localized quantum dot and continuous wetting layer states. The scattering rates are determined within the Boltzmann equation and within the orthogonalized plane wave approach. We go beyond the Hartree-Fock approximation and consider the Coulomb interaction up to the second order in the screened Coulomb potential.
Our simulations show the generation of relaxation oscillations in both the photon and charge carrier density dynamics. They start after a delay time of approximately 1ns that is due to the charge carrier filling of initially empty quantum dot states. The complex interplay between strongly nonlinear Coulomb scattering rates and radiative processes gives rise to the relaxation oscillations and determines their frequency and damping rate. In agreement with experiments, we obtain a strong damping of relaxation oscillations. Our results indicate the crucial importance of the Coulomb scattering processes for the understanding of the turn-on dynamics of quantum dot lasers.