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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 21 — Oct. 21, 2013
  • pp: 25381–25388

Effects of current crowding on light extraction efficiency of conventional GaN-based light-emitting diodes

Bin Cao, Shuiming Li, Run Hu, Shengjun Zhou, Yi Sun, Zhiying Gan, and Sheng Liu  »View Author Affiliations

Optics Express, Vol. 21, Issue 21, pp. 25381-25388 (2013)

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Current crowding effects (CCEs) on light extraction efficiency (LEE) of conventional GaN-based light-emitting diodes (LEDs) are analyzed through Monte Carlo ray-tracing simulation. The non-uniform radiative power distribution of the active layer of the Monte Carlo model is obtained based on the current spreading theory and rate equation. The simulation results illustrate that CCE around n-pad (n-CCE) has little effect on LEE, while CCE around p-pad (p-CCE) results in a notable LEE droop due to the significant absorption of photons emitted under p-pad. LEE droop is alleviated by a SiO2 current blocking layer (CBL) and reflective p-pad. Compared to the conventional LEDs without CBL, the simulated LEE of LEDs with CBL at 20 A/cm2 and 70 A/cm2 is enhanced by 7.7% and 19.0%, respectively. It is further enhanced by 7.6% and 11.4% after employing a reflective p-pad due to decreased absorption. These enhancements are in accordance with the experimental results. Output power of LEDs with CBL is enhanced by 8.7% and 18.2% at 20 A/cm2 and 70 A/cm2, respectively. And the reflective p-pad results in a further enhancement of 8.9% and 12.7%.

© 2013 OSA

OCIS Codes
(230.0230) Optical devices : Optical devices
(230.3670) Optical devices : Light-emitting diodes

ToC Category:
Optical Devices

Original Manuscript: May 23, 2013
Revised Manuscript: July 14, 2013
Manuscript Accepted: September 6, 2013
Published: October 17, 2013

Bin Cao, Shuiming Li, Run Hu, Shengjun Zhou, Yi Sun, Zhiying Gan, and Sheng Liu, "Effects of current crowding on light extraction efficiency of conventional GaN-based light-emitting diodes," Opt. Express 21, 25381-25388 (2013)

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