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Confocal microphotoluminescence of InGaN-based light-emitting diodes

Okamoto, Koichi and Kaneta, Akio and Kawakami, Yoichi and Fujita, Shigeo and Choi, Jungkwon and Terazima, Masahide and Mukai, Takashi (2005) Confocal microphotoluminescence of InGaN-based light-emitting diodes. Journal of Applied Physics, 98 (6). Art. No. 064503. ISSN 0021-8979. doi:10.1063/1.2037869.

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Spatially resolved photoluminescence (PL) of InGaN/GaN/AlGaN-based quantum-well-structured light-emitting diodes (LEDs) with a yellow-green light (530 nm) and an amber light (600 nm) was measured by using confocal microscopy. Submicron-scale spatial inhomogeneities of both PL intensities and spectra were found in confocal micro-PL images. We also found clear correlations between PL intensities and peak wavelength for both LEDs. Such correlations for yellow-green and amber LEDs were different from the reported correlations for blue or green LEDs. This discrepancy should be due to different diffusion, localization, and recombination dynamics of electron-hole pairs generated in InGaN active layers, and should be a very important property for influencing the optical properties of LEDs. In order to explain the results, we proposed a possible carrier dynamics model based on the carrier localization and partial reduction of the quantum confinement Stark effect depending on an indium composition in InGaN active layers. By using this model, we also considered the origin of the reduction of the emission efficiencies with a longer emission wavelength of InGaN LEDs with high indium composition.

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Additional Information:© 2005 American Institute of Physics. (Received 25 June 2004; accepted 28 July 2005; published online 19 September 2005) The authors wish to thank Professor A. Scherer, G. Maltezos, and A. Shvartser of California Institute of Technology for valuable discussions and reviewing the manuscript. This work was partly supported by Japan Society for the Promotion of Science (Grant No. 00122454) and the Kyoto University-Venture Business Laboratory Project.
Subject Keywords:light emitting diodes; photoluminescence; indium compounds; gallium compounds; aluminium compounds; III-V semiconductors; wide band gap semiconductors; quantum well devices; optical microscopy; semiconductor device models; quantum confined Stark effect
Issue or Number:6
Record Number:CaltechAUTHORS:OKAjap05
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1187
Deposited By: Archive Administrator
Deposited On:04 Jan 2006
Last Modified:08 Nov 2021 19:08

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