Impact of carrier localization, recombination, and diffusivity on excited state dynamics in InGaN/GaN quantum wells

T. Malinauskas; A. Kadys; T. Grinys; S. Nargelas; R. Aleksiejūnas; S. Miasojedovas; J. Mickevičius; R. Tomašiūnas; K. Jarašiūnas; M. Vengris; S. Okur; V. Avrutin; X. Li; F. Zhang; Ü. Özgür; H. Morkoç

doi:10.1117/12.906488

27 February 2012 Impact of carrier localization, recombination, and diffusivity on excited state dynamics in InGaN/GaN quantum wells

T. Malinauskas, A. Kadys, T. Grinys, S. Nargelas, R. Aleksiejūnas, S. Miasojedovas, J. Mickevičius, R. Tomašiūnas, K. Jarašiūnas, M. Vengris, S. Okur, V. Avrutin, X. Li, F. Zhang, Ü. Özgür, H. Morkoç

Author Affiliations +

Proceedings Volume 8262, Gallium Nitride Materials and Devices VII; 82621S (2012) https://doi.org/10.1117/12.906488
Event: SPIE OPTO, 2012, San Francisco, California, United States

Abstract

We apply a number of all-optical time-resolved techniques to study the dynamics of free carriers in InGaN quantum structures under high excitation regime. We demonstrate that carrier lifetime and diffusion coefficient both exhibit a substantial dependence on excitation energy fluence: with increasing carrier density, carrier lifetime drops and diffusivity increases; these effects become more apparent in the samples with higher indium content. We discuss these experimental facts within a model of diffusion-enhanced recombination, which is the result of strong carrier localization in InGaN. The latter model suggests that the rate of non-radiative recombination increases with excitation, which can explain the droop effect in InGaN. We use the ABC rate equation model to fit light induced transient grating (LITG) kinetics and show that that linear carrier lifetime drops with excitation (i.e. excess carrier density). We do not observe any influence of Auger recombination term, CN³, up to the maximum carrier density that is limited due to the onset of very fast stimulated recombination process. To support these conclusions, we present spectrally resolved differential transmission data revealing different recombination rates of carriers in localized and extended states.

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T. Malinauskas, A. Kadys, T. Grinys, S. Nargelas, R. Aleksiejūnas, S. Miasojedovas, J. Mickevičius, R. Tomašiūnas, K. Jarašiūnas, M. Vengris, S. Okur, V. Avrutin, X. Li, F. Zhang, Ü. Özgür, and H. Morkoç "Impact of carrier localization, recombination, and diffusivity on excited state dynamics in InGaN/GaN quantum wells", Proc. SPIE 8262, Gallium Nitride Materials and Devices VII, 82621S (27 February 2012); https://doi.org/10.1117/12.906488

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