Effect of quantum well non-uniformities on lasing threshold, linewidth, and lateral near field filamentation in violet (Al,In)GaN laser diodes
J. Jeschke1, U. Zeimer1, L. Redaelli1, S. Einfeldt1, M. Kneissl1,2, and M. Weyers1
Published in:
Appl. Phys. Lett., vol. 105, no. 17, 173501 (2014).
Abstract:
The lateral near field patterns and filamentation effects of gain guided broad area (Al,In)GaN-based laser diodes emitting around 415nm have been investigated. Diodes from the same laser bar, which are close to each other, show nearly the same number and widths of filaments. Comparison of different bars, which are from the same wafer but further apart from each other, reveals that a higher number of filaments correlates with a higher laser threshold and broader spectral linewidth. Cathodoluminescence mappings at 80K show strong variations of the quantum well band gap and hence of the emission wavelength for the bars with strong filamentation. These observations confirm previous theoretical predictions stating that large band gap fluctuations increase the threshold current and spectral linewidth. Furthermore, filamentation is enhanced as well because of a reduction of the carrier diffusion length.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
2 Institute of Solid State Physics, Technical University of Berlin, 10623 Berlin, Germany
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