Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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A Study of the Upper Layer for Improvement of the Extraction Efficiency in LED

LED 광 추출 효율 향상을 위한 상부 층 특성 고찰

  • Choi, Chul-Hyun (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University) ;
  • Lee, Dong-Jin (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University) ;
  • Yim, Hae-Dong (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University) ;
  • Kim, Bo-Soon (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University) ;
  • Sung, Jun-Ho (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University) ;
  • Lee, Min-Woo (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University) ;
  • O, Beom-Hoan (Optics and Photonics Elite Research Academy (OPERA), School of Information and Communication Engineering, INHA University)
  • 최철현 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터) ;
  • 이동진 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터) ;
  • 임해동 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터) ;
  • 김보순 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터) ;
  • 성준호 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터) ;
  • 이민우 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터) ;
  • 오범환 (인하대학교 정보통신공학부, 집적형 광자기술 연구센터)
  • Received : 2010.10.01
  • Accepted : 2011.02.14
  • Published : 2011.02.25
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Abstract

In this paper, we improved the light extraction efficiency by considering an additional upper layer on the top surface of a conventional LED. We simulated the LED's light emission as functions of the thickness and the refractive index of the upper layer, and analyzed how the condition improved the light efficiency. When the refractive index's range was from 1.05 to 1.40, the LED emission increased. For that case, the emission also increased as the thickness increased. We experimentally showed that the light extraction efficiency was improved about 22% by forming the upper layer on the top surface of an LED using material with refractive index 1.30 at 589.3 nm. It is expected that forming the upper layer on an LED can easily improve the extraction efficiency.

본 논문에서는 통상적인 LED 구조 위에 추가적으로 상부 층을 형성하여 LED의 광 추출 효율을 개선하였다. 상부 층의 두께 및 굴절률 변화에 따른 LED의 광 방출 특성을 전산모사하였고 광 추출 효율이 개선되는 조건을 분석하였다. 약 1.05~1.40의 굴절률 범위에서 LED의 광방출이 증가하였다. 또한, 이 범위에서 두께가 증가할수록 광방출이 증가하였다. 굴절률이 1.30@589.3 nm인 인덱스 매칭 액체를 실제 LED의 상부 층으로 형성하여 LED의 광 추출 효율이 약 22% 정도 향상됨을 실험적으로 보였다. 이렇게 LED 위에 상부 층을 형성하는 개념은 간단하게 LED의 광 추출 효율을 개선할 수 있을 것으로 기대된다.

Keywords

References

  1. M. S. Shur and R. Zukauskas, “Solid-state lighting: toward superior illumination,” Proc. IEEE 93, 1691-1703 (2005). https://doi.org/10.1109/JPROC.2005.853537
  2. M. H. Crawford, “LEDs for solid-state lighting: performance challenges and recent advances,” IEEE J. Select. Topics Quantum Electron. 15, 1028-1040 (2009). https://doi.org/10.1109/JSTQE.2009.2013476
  3. Y. K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, H. Zhao, J. F. Gilchrist, and N. Tansu, “Optimization of light extraction efficiency of III-Nitride LEDs with self-assembled colloidal-based microlenses,” IEEE J. Select. Topics Quantum Electron. 15, 1218-1225 (2009). https://doi.org/10.1109/JSTQE.2009.2015580
  4. S. C. Hsu, C. Y. Lee, J. M. Hwang, J. Y. Su, D. S. Wuu, and R. H. Horng, “Enhanced light output in roughened GaN-based light-emitting diodes using electrodeless photoelectrochemical etching,” IEEE Photon. Technol. Lett. 18, 2472-2474 (2006). https://doi.org/10.1109/LPT.2006.886862
  5. M. Boroditsky, T. F. Krauss, R. Coccioli, R. Vrijen, R. Bhat, and E. Yablonovitch, “Light extraction from optically pumped light-emitting diode by thin-slab photonic crystals,” Appl. Phys. Lett. 75, 1036-1038 (1993).
  6. J. H. Lee, J. T. Oh, S. B. Choi, Y. C. Kim, H. I. Cho, and J. H. Lee, “Enhancement of InGaN-based vertical LED with concavely patterned surface using patterned sapphire substrate,” IEEE Photon. Technol. Lett. 20, 345-347 (2008). https://doi.org/10.1109/LPT.2007.915648
  7. P. A. Porta, M. Harries, and H. D. Summers, “Surface plasmon mediated emission in resonant-cavity light-emitting diodes,” Appl. Phys. Lett. 89, 121120-1-121120-3 (2006). https://doi.org/10.1063/1.2357034

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