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Proceedings Paper

High-output power near-ultraviolet and violet light-emitting diodes fabricated on patterned sapphire substrates using metalorganic vapor phase epitaxy
Author(s): Kazuyuki Tadatomo; Hiroaki Okagawa; Youichiro Ohuchi; Takashi Tsunekawa; Hiromitsu Kudo; Yasuhide Sudo; Munehiro Kato; Tsunemasa Taguchi
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Paper Abstract

The external quantum efficiency (EQE, ηe) of conventional near-ultraviolet (NUV) light-emitting diodes (LEDs) with an InGaN multi-quantum-well (MQW) structure is limited by high dislocation density and by the narrow escape cone due to total internal reflection at the GaN/air or sapphire/air interface. We have fabricated the NUV and violet InGaN-MQW-LEDs with the high EQE on the patterned-sapphire substrate (PSS) using a single growth process by metal-organic vapor phase epitaxy (MOVPE). The PSS with parallel grooves along the <11-20>GaN direction or the <1-100>GaN direction was fabricated by a standard photolithography and subsequent reactive ion etching (RIE). In this study, fabricated the LED on the PSS with parallel grooves along the <11-20>GaN direction. The GaN layer grown by lateral epitaxy on a patterned substrate (LEPS) has dislocation density of 1.5x108 cm-2. The LEPS-NUV (or violet)-LED chips were mounted on the Si bases in a flip-chip bonding arrangement. When the LEPS-NUV-LED (the emission peak wavelength λp: 382 nm) was operated at a forward-bias current of 20 mA at room temperature (RT), the output power (Po) and the EQE were 15.6 mW and 24%, respectively. When the LEPS-violet-LED (λp: 405 nm) was operated at a forward-bias current of 20 mA at RT, the Po and the EQE were 26.3 mW and 43%, respectively. Furthermore, we obtained the Po of approximately 61 mW at 50 mA and 111 mW at 100 mA, respectively. It was revealed that the PSS is very effective in reducing the dislocation density and for increasing the extraction efficiency due to the multiple scattering of the emission light at the GaN/patterned sapphire interface.

Paper Details

Date Published: 26 January 2004
PDF: 7 pages
Proc. SPIE 5187, Third International Conference on Solid State Lighting, (26 January 2004); doi: 10.1117/12.513288
Show Author Affiliations
Kazuyuki Tadatomo, Mitsubishi Cable Industries, Ltd. (Japan)
Hiroaki Okagawa, Mitsubishi Cable Industries, Ltd. (Japan)
Youichiro Ohuchi, Mitsubishi Cable Industries, Ltd. (Japan)
Takashi Tsunekawa, Mitsubishi Cable Industries, Ltd. (Japan)
Hiromitsu Kudo, Mitsubishi Cable Industries, Ltd. (Japan)
Yasuhide Sudo, Mitsubishi Cable Industries, Ltd. (Japan)
Munehiro Kato, Stanley Electric Co., Ltd. (Japan)
Tsunemasa Taguchi, Yamaguchi Univ. (Japan)

Published in SPIE Proceedings Vol. 5187:
Third International Conference on Solid State Lighting
Ian T. Ferguson; Nadarajah Narendran; Steven P. DenBaars; John C. Carrano, Editor(s)

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