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Proceedings Paper

Impact of carrier localization, recombination, and diffusivity on excited state dynamics in InGaN/GaN quantum wells
Author(s): 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
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Paper 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.

Paper Details

Date Published: 27 February 2012
PDF: 8 pages
Proc. SPIE 8262, Gallium Nitride Materials and Devices VII, 82621S (27 February 2012); doi: 10.1117/12.906488
Show Author Affiliations
T. Malinauskas, Vilnius Univ. (Lithuania)
A. Kadys, Vilnius Univ. (Lithuania)
T. Grinys, Vilnius Univ. (Lithuania)
S. Nargelas, Vilnius Univ. (Lithuania)
R. Aleksiejūnas, Vilnius Univ. (Lithuania)
S. Miasojedovas, Vilnius Univ. (Lithuania)
J. Mickevičius, Vilnius Univ. (Lithuania)
R. Tomašiūnas, Vilnius Univ. (Lithuania)
K. Jarašiūnas, Vilnius Univ. (Lithuania)
Virgina Commonwealth Univ. (United States)
M. Vengris, Vilnius Univ. (Lithuania)
S. Okur, Virginia Commonwealth Univ. (United States)
V. Avrutin, Virginia Commonwealth Univ. (United States)
X. Li, Virginia Commonwealth Univ. (United States)
F. Zhang, Virginia Commonwealth Univ. (United States)
Ü. Özgür, Virginia Commonwealth Univ. (United States)
H. Morkoç, Virginia Commonwealth Univ. (United States)


Published in SPIE Proceedings Vol. 8262:
Gallium Nitride Materials and Devices VII
Jen-Inn Chyi; Yasushi Nanishi; Hadis Morkoç; Joachim Piprek; Euijoon Yoon, Editor(s)

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