Journal of Digital Convergence (디지털융복합연구)

The Society of Digital Policy and Management (한국디지털정책학회)
권호 표지
DOI QR코드

DOI QR Code

Enhanced Luminous Intensity in LEDs with Current Blocking Layer

전류 차단 층을 갖는 LED의 향상된 광세기

  • 윤석범 (공주대학교 광공학과) ;
  • 권기영 (공주대학교 전기전자제어공학부) ;
  • 최기석 (공주대학교 전기전자공학과)
  • Received : 2014.06.02
  • Accepted : 2014.07.20
  • Published : 2014.07.28
Download PDF
⟨ Previous Next ⟩

Abstract

Inserting a $SiO_2$ layer underneath the p-pad electrode as the current blocking layer (CBL) structure and extending p-metal finger patterns, the GaN LEDs using an indium-tin-oxide (ITO) layer show the improved light output intensity, resulting from better current spreading and reduced light loss on the surface of p-pad metal. The LEDs with an oxide layer of $100{\mu}m$-pad-width and $6{\mu}m$-finger-width have better light output intensities than those with an oxide layer of $105{\mu}m$-pad-width and $12{\mu}m$-finger-width. Using the ATLAS device simulator from Silvaco Corporation, the current density distributions on the active layer in CBL LEDs have been investigated.

GaN LED의 p-패드 금속과 에피층 사이에 $SiO_2$ 전류 절연 층을 제작하고, p-전극 금속의 패턴을 핑거(finger) 형태로 확장하여 형성함으로써, 대면적 고출력 소자에서 전류가 균일하게 퍼지도록 유도함과 동시에 p 패드 금속 표면에서의 광 손실을 줄여 광 출력을 증진시켰다. $SiO_2$ 절연 층의 면적과 두께를 다르게 하면서 광 출력의 증가를 비교 확인하였고, 실바코 사의 ATLAS 툴을 이용하여 컴퓨터 시뮬레이션을 실시함으로써 LED 내 활성 층에서의 전류 밀도 분포를 계산하였다. $SiO_2$ 절연 층의 두께가 $50{\mu}m$와 $100{\mu}m$ 인 두 경우 모두, p 패드의 직경이 $105{\mu}m$이고 핑거의 폭은 $12{\mu}m$인 경우와 비교할 때, p 패드의 직경이 $100{\mu}m$이고 핑거의 폭이 $6{\mu}m$인 경우가 더 높은 광 출력 특성을 나타냈다.

Keywords

References

  1. Min-Suk Oh, Min-Ki Kwon, Il-Kyu Park, Sung-Ho Baek, Seong-Ju Park, S.H. Lee, J.J. Jung, Improvement of green LED by growing p-GaN on In0.25Ga0.75N/GaN MQWs at low temperature. J. Crystal Growth, Elsevier, Vol. 289, No. 1, pp. 107-112, 2006. https://doi.org/10.1016/j.jcrysgro.2005.10.129
  2. C. Huh, J. M. Lee, D. J. Kim, and S. J. Park, Improvement in light-output efficiency of InGaN/GaN multiple-quantum well light-emitting diodes by current blocking layer. J. Appl. Phys., AIP, Vol. 92, pp. 2248-2250, 2002. https://doi.org/10.1063/1.1497467
  3. E. Fred Schubert, Light Emitting Diodes. England: Cambridge, 2006.
  4. E. F. Schubert and J. K. Kim, Solid-state light sources getting smart, Science. www.sciencemag.org, Vol. 308, pp. 1274-1278, 2005. https://doi.org/10.1126/science.1108712
  5. Chang S J, Shen C F, Chen W S, et al., Nitride-based LEDs with an insulating SiO2 layer underneath p-pad electrodes. Electro-chem Solid-State Lett, ECS, Vol. 10, No 6, pp. H175-H177, 2007. https://doi.org/10.1149/1.2718392
  6. Hadis Morkoc, Handbook of Nitride Semiconductors and Devices Vol. 3: GaN-based Optical and Electronic Devices, America: Wiley, 2009.
  7. Pei Wang, Wei Wei, Bin Cao, Zhiyin Gan, Sheng Liu, Simulation of current spreading for GaN-based light-emitting diodes. Optics & Laser Technology Vol. 42, Issue 5, pp. 737-740, July 2010. https://doi.org/10.1016/j.optlastec.2009.11.018
  8. Meng Lili, Chen Yixin, Ma Li, Liu Zike, and Shen Guangdi, ICP dry etching ITO to improve the performance of GaN-based LEDs. Journal of Semiconductors, IOP, Vol. 32, No. 1, pp. 014010-1-014010-4, 2011. https://doi.org/10.1088/1674-4926/32/1/014010
  9. Yang Hua, Wang Xiaofeng, Ruan Jun, Li Zhicong, Yi Xiaoyan, Duan Yao, Zeng Yiping, and Wang Guohong, Light extraction efficiency enhancement of GaN-based light emitting diodes by a ZnO current spreading layer, Journal of Semiconductors, Vol. 30, No. 9, pp. 094002-1-094002-4, Sept. 2009. https://doi.org/10.1088/1674-4926/30/9/094002
  10. Chun-Fu Tsai, Yan-Kuin Su, and Chun-Liang Lin, Improvement in the light output power of GaN-based light emitting diodes by one-step current blocking design. Jpn. J. Appl. Phys., JSAP, Vol. 50, No. 1(2), pp. 01AD05-1-01AD05-3, 2011. https://doi.org/10.7567/JJAP.50.01AD05
  11. Sang Youl Lee, Kwang Ki Choi, Hwan Hee Jeong, Eun Joo Kim, Hyo Kun Son, Sung Jin Son, June O Song, and Tae-Yeon Seong, Improved output power of GaN-based vertical light emitting diodes fabricated with current blocking region formed by $O_2$ plasma treatment. Jpn. J. Appl. Phys., JSAP, Vol. 50, No. 7(1), pp. 076504-1-076504-4, 2011. https://doi.org/10.7567/JJAP.50.076504
  12. S. Nakamura and G. Fasol, The Blue Laser Diode. Springer, America, 1997.
  13. Keon Hwa Lee, Ki Man Kang, Gi Cheol Hong, Seung Hwan Kim, Woo Young Sun, and Gye Mo Yang, Improved light extraction of GaN-based light-emitting diodes by an ion-damaged current blocking layer. Jpn. J. Appl. Phys., JSAP, Vol. 51, No. 8(1), pp. 082102-1-082102-4, 2012. https://doi.org/10.7567/JJAP.51.082102