Article abstract
Nature Materials 5, 810 - 816 (2006)
doi:10.1038/nmat1726
Subject Categories: Semiconductors | Optical, photonic and optoelectronic materials
Origin of defect-insensitive emission probability in In-containing (Al,In,Ga)N alloy semiconductors
Shigefusa F. Chichibu1,2, Akira Uedono1,3, Takeyoshi Onuma1,2, Benjamin A. Haskell2,4, Arpan Chakraborty4, Takahiro Koyama1,2, Paul T. Fini2,4, Stacia Keller4, Steven P. DenBaars2,4, James S. Speck2,4, Umesh K. Mishra4, Shuji Nakamura2,4, Shigeo Yamaguchi5,8, Satoshi Kamiyama5, Hiroshi Amano5, Isamu Akasaki5, Jung Han6 and Takayuki Sota7
Abstract
Group-III-nitride semiconductors have shown enormous potential as light sources for full-colour displays, optical storage and solid-state lighting. Remarkably, InGaN blue- and green-light-emitting diodes (LEDs) emit brilliant light although the threading dislocation density generated due to lattice mismatch is six orders of magnitude higher than that in conventional LEDs. Here we explain why In-containing (Al,In,Ga)N bulk films exhibit a defect-insensitive emission probability. From the extremely short positron diffusion lengths (<4 nm) and short radiative lifetimes of excitonic emissions, we conclude that localizing valence states associated with atomic condensates of In–N preferentially capture holes, which have a positive charge similar to positrons. The holes form localized excitons to emit the light, although some of the excitons recombine at non-radiative centres. The enterprising use of atomically inhomogeneous crystals is proposed for future innovation in light emitters even when using defective crystals.
- Institute of Applied Physics and 21st Century COE Office, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai,Tsukuba 305-8573, Japan
- Nakamura Inhomogeneous Crystal Project, ERATO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi 332-0012, Japan
- Nanomaterials Laboratory, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003, Japan
- Departments of Electrical and Computer Engineering and Materials Engineering, University of California, Santa Barbara, California 93106, USA
- High-Tech Research Centre, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468-8502, Japan
- Technical Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520, USA
- Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Ohkubo, Shinjuku 169-8555, Japan
- Present address: Department of Electrical, Electronic and Information Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan
Correspondence to: Shigefusa F. Chichibu1,2 e-mail: chichibu@alumni.engr.ucsb.edu
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