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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 5 — Mar. 11, 2013
  • pp: 6353–6359

Enhanced luminous efficacy in phosphor-converted white vertical light-emitting diodes using low index layer

Seung Hwan Kim, Young Ho Song, Seong Ran Jeon, Tak Jeong, Ja Yeon Kim, Jun Seok Ha, Wan Ho Kim, Jong Hyeob Baek, Gye Mo Yang, and Hyung Jo Park  »View Author Affiliations

Optics Express, Vol. 21, Issue 5, pp. 6353-6359 (2013)

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We demonstrated improved luminous efficacy for GaN-based vertical light emitting diodes (VLEDs) employing a low index layer composed of silicon dioxide (SiO2) on the top surface. Three-dimensional ðnite-difference time-domain simulations for the fabricated VLED chip show that the penetration ratio of the emitted/reflected light into the VLED chip decreased by approximately 20% compared to a normal VLED chip. This result is in good agreement with an empirical study stating that white VLEDs having a SiO2 layer exhibit an 8.1% higher luminous efficacy than white VLEDs with no layer at an injection current of 350 mA. Photons penetrating into the VLED chip, which become extinct in the VLED chip, are reflected from the SiO2 layer due to the index contrast between the SiO2 layer and epoxy resin containing phosphor, with no degradation of the light-extraction efficiency of the VLED chip. As such, this structure can contribute to the enhancement of the luminous efficacy of VLEDs.

© 2013 OSA

OCIS Codes
(160.6000) Materials : Semiconductor materials
(230.3670) Optical devices : Light-emitting diodes
(240.6645) Optics at surfaces : Surface differential reflectance

ToC Category:
Optical Devices

Original Manuscript: December 27, 2012
Revised Manuscript: February 16, 2013
Manuscript Accepted: February 26, 2013
Published: March 6, 2013

Seung Hwan Kim, Young Ho Song, Seong Ran Jeon, Tak Jeong, Ja Yeon Kim, Jun Seok Ha, Wan Ho Kim, Jong Hyeob Baek, Gye Mo Yang, and Hyung Jo Park, "Enhanced luminous efficacy in phosphor-converted white vertical light-emitting diodes using low index layer," Opt. Express 21, 6353-6359 (2013)

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  1. S. Noda and M. Fujita, “Light-emitting diodes: Photonic crystal efficiency boost,” Nat. Photonics3(3), 129–130 (2009). [CrossRef]
  2. J. J. Wierer, A. David, and M. M. Megens, “III-nitride photonic-crystal light-emitting diodes with high extraction efficiency,” Nat. Photonics3(3), 163–169 (2009). [CrossRef]
  3. S. Pimputkar, J. S. Speck, S. P. DenBaars, and S. Nakamura, “Prospects for LED lighting,” Nat. Photonics3(4), 180–182 (2009). [CrossRef]
  4. N. Narendran, N. Maliyagoda, L. Deng, and R. M. Pysar, “Characterizing LEDs for general illumination applications: mixed-color and phosphor-based white sources,” Proc. SPIE4445, 137–147 (2001). [CrossRef]
  5. T. Nishida, T. Ban, and N. Kobayashi, “High-color-rendering light sources consisting of a 350-nm ultraviolet light-emitting diode and three-basal-color phosphors,” Appl. Phys. Lett.82(22), 3817–3819 (2003). [CrossRef]
  6. H. C. Chen, K. J. Chen, C. H. Wang, C. C. Lin, C. C. Yeh, H. H. Tsai, M. H. Shih, H. C. Kuo, and T. C. Lu, “A novel randomly textured phosphor structure for highly efficient white light-emitting diodes,” Nanoscale Res. Lett.7(1), 188–192 (2012). [CrossRef] [PubMed]
  7. T. Doan, C. Tran, C. Chu, C. Chen, W. H. Liu, J. Chu, K. Yen, H. Chen, and F. Fan, “Vertical GaN based light emitting diodes on metal alloy substrate boosts high power LED performance,” Proc. SPIE6669, 666903, 666903-8 (2007). [CrossRef]
  8. N. Narendran, Y. Gu, J. P. Freyssinier-Nova, and Y. Zhu, “Extracting phosphor-scattered photons to improve white LED efficiency,” Phys. Status Solidi A202(6), R60–R62 (2005). [CrossRef]
  9. J. K. Kim, H. Luo, E. F. Schubert, J. Cho, C. Sone, and Y. Park, “Strongly enhanced phosphor efficiency in GaInN white light-emitting diodes using remote phosphor configuration and diffuse reflector cup,” Jpn. J. Appl. Phys.44(21), L649–L651, L651 (2005). [CrossRef]
  10. K. Yamada, Y. Imai, and K. Ishii, “Optical simulation of light source devices composed of Blue LEDs and YAG phosphor,” J. Light Vis. Environ.27(2), 70–74 (2003). [CrossRef]
  11. J. R. Oh, S. H. Cho, Y. H. Lee, and Y. R. Do, “Enhanced forward efficiency of Y3Al5O12:Ce3+ phosphor from white light-emitting diodes using blue-pass yellow-reflection filter,” Opt. Express17(9), 7450–7457 (2009). [CrossRef] [PubMed]
  12. N. T. Tran, J. P. You, and F. G. Shi, “Effect of phosphor particle size on luminous efficacy of phosphor-converted white LED,” J. Lightwave Technol.27(22), 5145–5150 (2009). [CrossRef]
  13. S. C. Allen and A. J. Steckl, “A nearly ideal phosphor-converted white light-emitting diode,” Appl. Phys. Lett.92(14), 143309 (2008). [CrossRef]
  14. H. Luo, J. K. Kim, Y. A. Xi, E. F. Schubert, J. Cho, C. Sone, and Y. Park, “Trapped whispering-gallery optical modes in white light-emitting diode lamps with remote phosphor,” Appl. Phys. Lett.89(4), 041125 (2006). [CrossRef]
  15. S. K. Kim, H. K. Cho, D. K. Bae, J. S. Lee, H.-G. Park, and Y.-H. Lee, “Efficient GaN Slab vertical light-emitting diode covered with a patterned high-index layer,” Appl. Phys. Lett.92(24), 241118 (2008). [CrossRef]
  16. E. F. Schubert, Light-Emitting Diode, 2nd ed. (Cambridge University, 2006).
  17. H.-S. Kwack, H. S. Lim, H.-D. Song, S.-H. Jung, H. K. Cho, H.-K. Kwon, and M. S. Oh, “Experimental study of light output power for vertical GaN-based light-emitting diodes with various textured surface and thickness of GaN layer,” AIP Advances2(2), 022127 (2012). [CrossRef]
  18. H. M. Ng, N. G. Weimann, and A. Chowdhury, “GaN nanotip pyramids formed by anisotropic etching,” J. Appl. Phys.94(1), 650–652 (2003). [CrossRef]

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