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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)
http://dx.doi.org/10.1364/OE.21.006353


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Abstract

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

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

Citation
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)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-5-6353


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