Development of Dual MQW Region LEDs for General Illumination
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E10.3.1
Development of Dual MQW Region LEDs for General Illumination David Brackin Nicol1, Ali Asghar1, Martin Strassburg1,3, My Tran1, Ming Pan1, Hun Kang1, Ian T. Ferguson1,2*, Mustafa Alevi3, Jayantha Senawiratne3, Christoph Hums3,4, Nikolaus Dietz3, Axel Hoffmann4 1
Georgia Institute of Technology, School of Electrical and Computer Engineering, Atlanta, GA 30332-0250, U.S.A. 2 Georgia Institute of Technology, School of Materials Science and Engineering, Atlanta, GA 30332, U.S.A. 3 Georgia State University, Department of Physics and Astronomy, Atlanta, GA 30302303024106, U.S.A. 4 Institute of Solid State Physics, Technical University of Berlin, 10623 Berlin, Germany ABSTRACT Dual Multi-Quantum Well (MQW) region light emitting diodes (LEDs) for efficient pumping of multiple phosphors have been grown by Metal Organic Chemical Vapor Deposition (MOCVD), for use in broadband, white solid state light sources. Blue (460 nm) and Violet/UV (~400-420 nm) emitting MQW regions were incorporated into one device and show recombination mechanisms similar to single MQW region devices. The introduction of a decoupling region successfully separated the electroluminescent emissions, and two distinct emission peaks were observed. These devices can be used to pump a variety of phosphors designed for blue and UV sources, allowing for more design flexibility in color rendering and color temperature attributes of solid state light sources. INTRODUCTION Significant penetration of solid state lighting into the general illumination market depends on the development of high quality white sources retaining the efficiencies seen in current LEDs. In particular, Gallium Nitride (GaN)-based materials have become very important for many optoelectronic applications, with the development of new illumination sources based on LEDs [1]. GaN-based LEDs have fueled a revolution in the lighting industry called Solid State Lighting (SSL). SSL is prevalent in markets such as traffic signals, large area displays, signage, and backlighting. Low cost, high efficiency, high flux, and good quality white light are required attributes for a new general illumination source to become prevalent. High quality, white solid state light sources have not been widely realized while preserving efficiency and flux seen in first generation white LED sources. White LED sources can be created by a range of methods including red-green-blue (RGB) discrete LEDs and proper color mixing, and LED pumped-phosphor sources. High quality white light should have a high color rendering capability with the ability to achieve a range of desired correlated color temperatures. First generation white LEDs employing a blue LED pump and an yttrium aluminum garnet (YAG) phosphor emitting in the yellow region of the spectrum have shown high flux but lack good color rendering and low *
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E10.3.2
Intensity (arb. units)
correlated color temperatures. However, 1.2 broadband white LED sources using different 416.96 Pump Peak pumps and phosphors can achieve high color 1.0 render
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