Quantum Optoelectronics

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Progress in the optical studies of single InGaN/GaN quantum dots

PHILOSOPHICAL MAGAZINE 87:13 (2007) 2077-2093

Authors:

AF Jarjour, RA Oliver, RA Taylor
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Roughness analysis of GaN surfaces at different annealing temperatures for an AlN buffer layer

JOURNAL OF THE KOREAN PHYSICAL SOCIETY 51:1 (2007) 209-213

Authors:

MK Bae, DH Shin, SN Yi, SH Doh, JH Na, KH Lee, RA Taylor, SH Park
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Two-Photon Excitation of Asymmetric GaN/AlGaN Quantum Discs

AIP Conference Proceedings AIP 893 (2007) 981-982

Authors:

Kwan H Lee, Jong H Na, Stefan Birner, Sam N Yi, Robert A Taylor, Young S Park, Chang M Park, Tae W Kang
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Two-photon excitation of asymmetric GaN/AlGaN quantum discs

AIP CONF PROC 893 (2007) 981-982

Authors:

KH Lee, JH Na, S Birner, SN Yi, RA Taylor, YS Park, CM Park, TW Kang

Abstract:

By using two-photon absorption spectroscopy we have performed time-integrated and time-resolved photolurninescence measurements on several coupled asymmetric GaN quantum discs, with embedded AlGaN barriers. We observe free-carrier screening, with an enhancement due to tunneling between the coupled quantum discs.
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Free carrier screening in coupled asymmetric GaN quantum discs

Proceedings of SPIE - The International Society for Optical Engineering 6352 I (2006)

Authors:

KH Lee, JH Na, S Birner, RA Taylor, SN Yi, YS Park, CM Park, TW Kang

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.
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