Dresden 2009 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 7: Nanophotonics - Theory of Nanophotonic Devices III
DS 7.3: Vortrag
Montag, 23. März 2009, 16:30–16:45, GER 38
Microscopic modelling of Auger losses in wide bandgap nitrides — •Jörg Hader1,2, Jerome V. Moloney1,2, Bernhard Pasenow3, and Stephan W. Koch3 — 1Nonlinear Control Strategies Inc., 3542 N. Geronimo Ave., Tucson, AZ 85705, USA — 2College of Optical Sciences, University of Arizona, Tucson, AZ 85721, USA — 3Fachbereich Physik und Wissenschaftliches Zentrum für Materialwissenschaften, Philipps-Univrsität Marburg, Renthof 5, 35032 Marburg, Germany
The internal quantum efficiency in GaN-based light emitting diodes is generally found to have a maximum at very low pump densities and to fall off for higher densities. Using phenomenological models, this efficiency ’droop’ can be fitted asuming a non-radiative loss mechanism that has the cubic density dependence usually associated with Auger recombination losses. Here, we use a set of fully microscopic models to investigate the actual importance of Auger losses in these systems. We give a brief description of the involved models for absorption/gain, spontaneous emission and carrier losses due to radiative and direct and phonon-assisted Auger losses. The predicitve nature of these fit-parameter free models is demonstrated and shortcomings of simplified phenomenological models are discussed - in particular, the general failure of the cubic density dependence for Auger losses. It is shown that direct Auger losses cannot explain the efficiency droop[1] and the possible impact of phonon-assisted processes is analyzed.
[1] J. Hader, et al., Appl. Phys. Lett. 92, 261103 (2008)