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Proceedings Paper

Free carrier screening in coupled asymmetric GaN quantum discs
Author(s): K. H. Lee; J. H. Na; S. Birner; R. A. Taylor; S. N. Yi; Y. S. Park; C. M. Park; T. W. Kang
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Paper Abstract

We present an investigation of free-carrier screening in coupled asymmetric GaN quantum discs with embedded AlGaN barriers using time-integrated and time-resolved micro-photoluminescence measurements, supported by three-dimensional multi-band k.p computational modeling. We observe that with increasing optical excitation the carrier lifetime decreases and emission energy blue-shifts. This originates from the screening of built-in piezo- and pyroelectric fields in the quantum discs by photo-generated free-carriers. Due to non-resonant tunneling of carriers from the smaller disc to the larger disc, free carrier screening is enhanced in the larger disc. The non-resonant tunneling was found to have a significant role in samples with a thin barrier, as the screening decreased with barrier thickness (i.e. decreased tunneling). Computational modeling was in good agreement with the experimental results.

Paper Details

Date Published: 6 October 2006
PDF: 9 pages
Proc. SPIE 6352, Optoelectronic Materials and Devices, 635214 (6 October 2006); doi: 10.1117/12.689176
Show Author Affiliations
K. H. Lee, Univ. of Oxford (United Kingdom)
J. H. Na, Univ. of Oxford (United Kingdom)
S. Birner, Technical Univ. of Munich (Germany)
R. A. Taylor, Univ. of Oxford (United Kingdom)
S. N. Yi, Univ. of Oxford (United Kingdom)
Y. S. Park, Dongguk Univ. (South Korea)
C. M. Park, Dongguk Univ. (South Korea)
T. W. Kang, Dongguk Univ. (South Korea)

Published in SPIE Proceedings Vol. 6352:
Optoelectronic Materials and Devices
Yong Hee Lee; Fumio Koyama; Yi Luo, Editor(s)

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