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Proceedings Paper

Progress in III-nitride-based white light sources
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Paper Abstract

We review two complementary approaches to the development of white light solid-state sources. The first approach, which involves polychromatic LED modules, is targeted at advanced optimization of spectral power distribution in order to establish an optimal trade-off between luminous efficacy and color rendering. We apply a stochastic method of optimization of a white-light source that relies on additive color mixing of the emissions from colored primary LEDs. We present the results on optimized spectra for all-semiconductor lamps composed of four primary LEDs with the line widths typical of present AlGaInP and AlInGaN technologies. We point out the problem of the lack of efficient yellow-green (570 nm) emitters required for polychromatic lamps with four and more primary LEDs. The second approach is based on the development of AlInGaN-based UV emitters that can be tailored to directly excite different phosphors without sensitizers. AlInGaN materials system demonstrated potential for making UV LEDs with a high power and short wavelengths required for such applications. This has been achieved by using Strain Energy Band Engineering (SEBE) and Pulsed Atomic Epitaxy (PALE) techniques. SEBE relies on quaternary AlGaInN compounds for controlling strain and band offset and for producing UV emitters with improved device performance. PALE allows us to incorporate the required significant amount of indium (few percent) in AlGaN, since it can be performed at lower growth temperatures required for In incorporation. Further improvements in materials quality of AlInGaN layers with a high molar fraction of Al will be achieved by using bulk AlN substrates.

Paper Details

Date Published: 26 November 2002
PDF: 15 pages
Proc. SPIE 4776, Solid State Lighting II, (26 November 2002); doi: 10.1117/12.457167
Show Author Affiliations
Remis Gaska, Sensor Electronic Technology, Inc. (United States)
Arturas Zukauskas, Vilnius Univ. (Lithuania)
Rensselaer Polytechnic Institute (United States)
Michael S. Shur, Rensselaer Polytechnic Institute (United States)
Mohamed Asif Khan, Univ. of South Carolina (United States)

Published in SPIE Proceedings Vol. 4776:
Solid State Lighting II
Ian T. Ferguson; Nadarajah Narendran; Steven P. DenBaars; Yoon-Soo Park, Editor(s)

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