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HL: Fachverband Halbleiterphysik
HL 45: Group-III-Nitrides: Optical Properties II
HL 45.2: Vortrag
Mittwoch, 24. März 2010, 14:45–15:00, H15
Auger Coefficient in GaInN-based Laser Structures — •Alexander Daniel Dräger, Carsten Netzel, Moritz Brendel, Holger Jönen, Uwe Rossow, and Andreas Hangleiter — Institut für Angewandte Physik, TU Braunschweig
Todays GaInN-based light emitting devices such as LEDs and laser diodes show excellent properties in terms of quantum efficiency or threshold current in the violet-blue spectral region. With increasing wavelength towards the green this performance decreases strongly. In particular at longer wavelengths, the quantum efficiency decreases for higher current densities, called the efficiency droop. This phenomenon is still subject to intensive research and different mechanisms such as Auger recombination, losses due to dislocations and carrier escape have been named as possible explanations. We combine optical gain measurements using the variable stripe length technique with model calculations of the optical gain spectra to derive the carrier lifetime. From the dependence of the inverse effective lifetime on carrier density we determine the recombination coefficients for radiative, nonradiative and Auger recombination. The Auger coefficients we obtained are about 1-2×10−31 cm6/s for GaInN quantum wells with 2.5eV<Eg<3.1eV which is more than an order of magnitude lower than estimated from photoluminescence [1] and thus too low to explain the LED droop. Nevertheless, Auger recombination seems to contribute to laser threshold.
[1] Shen et. al. APL 91, 141101(2007)