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Chip Size-Dependent Light Extraction Efficiency for Blue Micro-LEDs

청색 마이크로 LED의 광 추출 효율에 미치는 칩 크기 의존성 연구

  • Park, Hyun Jung (Department of Printed Electronics Engineering, Sunchon National University) ;
  • Cha, Yu-Jung (Department of Printed Electronics Engineering, Sunchon National University) ;
  • Kwak, Joon Seop (Department of Printed Electronics Engineering, Sunchon National University)
  • 박현정 (순천대학교 인쇄전자공학과) ;
  • 차유정 (순천대학교 인쇄전자공학과) ;
  • 곽준섭 (순천대학교 인쇄전자공학과)
  • Received : 2018.09.20
  • Accepted : 2018.10.12
  • Published : 2019.01.01

Abstract

Micro-LEDs show lower efficiencies compared to general LEDs having large areas. Simulations were carried out using ray-tracing software to investigate the change in light extraction efficiency and light distribution according to chip-size of blue flip-chip micro-LEDs (FC ${\mu}-LEDs$). After fixing the height of the square FC ${\mu}-LED$ chip at $158{\mu}m$, the length of one side was varied, with dimensions of 2, 5, 10, 30, 50, 100, 300, and $500{\mu}m$. The highest light-extraction efficiency was obtained at $10{\mu}m$, beyond which the efficiency decreased as the chip-size increased. The chip size-dependence of the FC ${\mu}-LEDs$ both without the patterned sapphire substrate, as well as vertical FC ${\mu}-LEDs$, were analyzed.

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Fig. 1. Cross-sectional image of the FC μ-LEDs.

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Fig. 4. Far-field light intensity angular distribution for the FC Fig. 2. (a) Result of light extraction efficiency and (b) side/top ratio according to changing the length of one side of the FC μ-LEDs.

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Fig. 5. Image of the ray tracing according to changing thelength of one side of the FC μ-LEDs.

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Fig. 7. Far-field light intensity angular distribution for the nonPSS FC μ-LEDs.

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Fig. 9. Far-field light intensity angular distribution for the verticalFC μ-LEDs.

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Fig. 10. Light extraction efficiency of (a) total, (b) top, and (c) 4 sides area according to changing the length of one side of the LEDs.

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Fig. 2. (a) Result of light extraction efficiency and (b) side/top ratio according to changing the length of one side of the FC μ-LEDs.

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Fig. 6. (a) Result of light extraction efficiency and (b) side/top ratio according to changing the length of one side of the non PSS FC μ-LEDs.

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Fig. 8. (a) Result of light extraction efficiency and (b) side/top ratio according to changing the length of one side of the vertical FC μ-LEDs.

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Fig. 3. Image of the side irradiance according to changing the length of one side of the FC Fig. 2. (a) Result of light extraction efficiency and (b) side/top ratio according to changing the length of one side of the FC μ-LEDs.

Table 1. Height and refractive index of the each layer.

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Acknowledgement

Supported by : 한국연구재단

References

  1. J. Piprek, Phys. Status Solidi A, 207, 2217 (2010). [DOI: https://doi.org/10.1002/pssa.201026149] https://doi.org/10.1002/pssa.201026149
  2. Y. C. Shen, G. O. Mueller, S. Watanabe, N. F. Gardner, A. Munkholm, and M. R. Krames, Appl. Phys. Lett., 91, 141101 (2007). [DOI: https://doi.org/10.1063/1.2785135] https://doi.org/10.1063/1.2785135
  3. M. H. Kim, M. F. Schubert, Q. Dai, J. K. Kim, E. F. Schubert, J. Piprek, and Y. Park, Appl. Phys. Lett., 91, 183507 (2007). [DOI: https://doi.org/10.1063/1.2800290] https://doi.org/10.1063/1.2800290
  4. X. Ni, Q. Fan, R. Shimada, U. Ozgur, and H. Morkoc, Appl. Phys. Lett., 93, 171113 (2008). [DOI: https://doi.org/10.1063/1.3012388] https://doi.org/10.1063/1.3012388
  5. Y. Yang, X. A. Cao, and C. Yan, IEEE Trans. Electron Devices, 55, 1771 (2008). [DOI: https://doi.org/10.1109/TED.2008.923561] https://doi.org/10.1109/TED.2008.923561
  6. J. Hader, J. V. Moloney, and S. W. Koch, Appl. Phys. Lett., 96, 221106 (2010). [DOI: https://doi.org/10.1063/1.3446889] https://doi.org/10.1063/1.3446889
  7. Y. Y. Kudryk and A. V. Zinovchuk, Semicond. Sci. Technol., 26, 095007 (2011). [DOI: https://doi.org/10.1088/0268-1242/26/9/095007] https://doi.org/10.1088/0268-1242/26/9/095007
  8. Z. Gong, S. Jin, Y. Chen, J. McKendry, D. Massoubre, I. M. Watson, E. Gu, and M. D. Dawson, J. Appl. Phys., 107, 013103 (2010). [DOI: https://doi.org/10.1063/1.3276156] https://doi.org/10.1063/1.3276156
  9. P. Tian, J.J.D. McKendry, Z. Gong, B. Guilhabert, I. M. Watson, E. Gu, Z. Chen, G. Zhang, and M. D. Dawson, Appl. Phys. Lett., 101, 231110 (2012). [DOI: https://doi.org/10.1063/1.4769835] https://doi.org/10.1063/1.4769835
  10. T. K. Kim, M. U. Cho, J. M. Lee, Y. J. Cha, S. K. Oh, B. Chatterjee, J. H. Ryou, S. Choi, and J. S. Kwak, Phys. Status Solidi A, 215, 1700571 (2018). [DOI: https://doi.org/10.1002/pssa.201700571] https://doi.org/10.1002/pssa.201700571
  11. T. Jeong, Inf. Disp., 17, 18 (2016).
  12. S. J. Park, LED Light extraction technology, http://webzine. kps.or.kr/contents/data/webzine/webzine/14762094724.pdf (2008).
  13. H. J. Park, D. K. Lee, and J. S. Kwak, J. Korean Inst. Electr. Electron. Mater. Eng., 28, 676 (2015). [DOI: https://doi.org/10.4313/JKEM.2015.28.10.676] https://doi.org/10.4313/JKEM.2015.28.10.676
  14. S. S. Kim, J. W. Lee, and B. J. Jeon, J. Korean Inst. Electr. Electron. Mater. Eng., 30, 800 (2017). [DOI: https://doi.org/10.4313/JKEM.2017.30.12.800] https://doi.org/10.4313/JKEM.2017.30.12.800
  15. S. J. Hwang and J. S. Kwak, J. Korean Inst. Electr. Electron. Mater. Eng., 30, 175 (2017). [DOI: https://doi.org/10.4313/JKEM.2017.30.3.175] https://doi.org/10.4313/JKEM.2017.30.3.175
  16. M. S. Jang, W. H. Kim, Y. R, Kang, K. H. Kim, S. B. Song, J. H. Kim, and J. P. Kim, J. Korean Inst. Electr. Electron. Mater. Eng., 25, 849 (2012). [DOI: https://doi.org/10.4313/JKEM.2012.25.10.849] https://doi.org/10.4313/JKEM.2012.25.10.849
  17. K. S. Shin, D. Y. Kim, and T. G. Kim, J. Korean Inst. Electr. Electron. Mater. Eng., 24, 911 (2011). [DOI: https://doi.org/10.4313/JKEM.2011.24.11.911] https://doi.org/10.4313/JKEM.2011.24.11.911