Temperature-Dependent Charge Carrier Diffusion in [0001] Direction of GaN Determined by Luminescence Evaluation of Buried InGaN Quantum Wells

C. Netzela, V. Hoffmanna, J.W. Tommb, F. Mahlerb, S. Einfeldta, and M. Weyersa

Published in:

phys. stat. sol. (b), vol. 257, no. 6, pp. 2000016, doi:10.1002/pssb.202000016 (2020).

Copyright © 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.


Temperature-dependent transport of photoexcited charge carriers through a nominally undoped, c-plane GaN layer toward buried InGaN quantum wells is investigated by continuous-wave and time-resolved photoluminescence spectroscopy. The excitation of the buried InGaN quantum wells is dominated by charge carrier diffusion through the GaN layer; photon recycling contributes only slightly. With temperature decreasing from 310 to 10 K, the diffusion length in [0001] direction increases from 250 to 600 nm in the GaN layer. The diffusion length at 300 K also increases from 100 to 300 nm when increasing the excitation power density from 20 to 500 W cm-2. The diffusion constant decreases from the low-temperature value of ∼7 to 1.5 cm2s-1 at 310 K. The temperature dependence of the diffusion constant indicates that the diffusivity at room temperature is limited by optical phonon scattering. Consequently, higher diffusion constants in GaN-based devices require a reduced operation temperature. To increase diffusion lengths at afixed temperature, the effective recombination time has to be prolonged by reducing the number of nonradiative recombination centers.

a Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
b Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2A, 12489 Berlin, Germany


diffusion constants, diffusion lengths, gallium nitride