Study of excess carrier dynamics in polar, semi-polar, and nonpolar InGaN epilayers and QWs
R. Aleksiejunas1, L. Lubys1, M. Vengris2, K. Jarasiunas1, T. Wernicke3, V. Hoffmann3, C. Netzel3, A. Knauer3, M. Weyers3, M. Kneissl3,4
Published in:
phys. stat. sol. (c), vol. 8, no. 7-8, pp. 2154-2156 (2011).
Abstract:
We studied carrier recombination and diffusion inGaN/sapphire templates, (In,Ga)N layers, and (In,Ga)Nquantum well structures oriented along the polar [0001],semi-polar [11-22], and non-polar [11-20] orientations bymeans of light induced transient grating, differentialtransmission, and photoluminescence optical techniques.We show that the lifetime of excess carriers drops by ordersof magnitude when changing the orientation frompolar to non-polar, both in GaN templates and (In,Ga)Nlayers. We attribute the shorter lifetime to carrier trappingby extended structural defects that are more abundantin non-polar grown samples. In addition, we observepronounced carrier localization effects in the semi- andnon-polar layers. We show that thick (In,Ga)N layers inheritthe properties of the GaN templates. However, thethin quantum well structures show a lower carrier trappingactivity. So, a better electrical quality can be assumedas compared to the thick (In,Ga)N layers.
1 Institute of Applied Research, Vilnius University, Sauletekio Ave. 9-III, 10222 Vilnius, Lithuania
2 Laser Research Center, Vilnius University, Sauletekio Ave. 10, 10222 Vilnius, Lithuania
3 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, 12489 Berlin, Germany
4Institute of Solid State Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
Keywords:
(In,Ga)N, carrier transport, non-polar, semi-polar.
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