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HL: Fachverband Halbleiterphysik
HL 35: Semiconductor laser
HL 35.6: Vortrag
Dienstag, 17. März 2015, 12:30–12:45, EW 203
Microscopic model for intersubband gain from electrically pumped quantum-dot structures — •Stephan Michael1, Weng Wah Chow2, and Hans Christian Schneider1 — 1Department of Physics, University of Kaiserslautern, P.O. Box 3049, 67653 Kaiserslautern, Germany — 2Sandia National Laboratories, Albuquerque, NM 87185-1086, USA
Quantum cascade lasers (QCLs) based on quantum wells (QWs) has been an exciting topic of research for decades. QCLs can operate up to and above room temperature and can produce a high output power. An alternative would be QCLs consisting of self-assembled quantum dots (QDs). Steps in this direction are midinfrared photodetectors using QDs, which include the demonstration of midinfrared electroluminescence at low and more recently also in room temperature. In this contribution, we investigate theoretically the performance of electrically pumped self-organized QDs as gain material in the mid-IR range at room temperature. Therefore, we analyze a comprehensive model based on an AlGaAs structure composed of dots-in a-well sandwiched between two QWs. We find that steady-state gain requires an efficient extraction process, that prevents an accumulation of electrons in the continuum states of the QDs. However, comparing the modal gain to a standard QW structure as used in QCLs, our calculation predict reduced threshold current densities of the QD structure for comparable modal gain. But this is only possible for an inhomogeneous broadening of a QD ensemble that is close to the lower limit achievable today using self-organized growth.