C. Mounir¹, U.T. Schwarz¹, I.L. Koslow^2,3, M. Kneissl^2,3, T. Wernicke², T. Schimpke⁴, M. Strassburg⁴

Published in:

Phys. Rev. B, vol. 93, no. 23, pp. 235314 (2016).

Abstract:

We investigate the influence of inhomogeneous broadening on the optical polarization properties of high-inclination semipolar and nonpolar In_xGa_1-xN/GaN quantum wells. Different planar m-plane and (2021) samples were grown (including core-shell microrods) and have been characterized by excitation-dependent polarizationresolved confocal micro-photoluminescence. The measured degree of linear polarization (DLP) is compared to theoretical predictions obtained by Fermi-Dirac statistical filling of the electronic band structure calculated by the k · p envelope function method. We show that our measured DLP at room temperature, as well as values reported by other groups, are systematically higher than the theoretical predictions. We propose to solve this discrepancy between theory and experiment by introducing inhomogeneous broadening in our calculations. Considering indium content fluctuations and the localization lengths of electrons and holes, different effective broadenings are applied to different subsets of subbands.We thereby show that inhomogeneous broadening leads to an increase of the DLP at room temperature. Furthermore, the dependence of the optical properties on the excitation density is better reproduced. Looking at the DLP as a function of the temperature gives us insight into the thermalization dynamics of charge carriers.

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