FDTD analysis on extraction efficiency of GaN light-emitting diodes with microsphere arrays

Peifen Zhu*, Guangyu Liu, Jing Zhang, Nelson Tansu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

99 Scopus citations


The improvement of light extraction efficiency of InGaN light-emitting diodes (LEDs) using microsphere arrays with various refractive indices was analyzed. Finite-difference time-domain (FDTD) simulations show that the use of microsphere (dmicrosphere = 500 nm) arrays with refractive indices of 1.8 and 2.5 led to increase in light extraction efficiency of InGaN LEDs by 1.9 times and 2.2 times, respectively. The enhancement in light extraction efficiency is attributed to the decrease in the Fresnel reflection and increase in effective photon escape cone due to graded refractive index and curvature formed between microsphere and free space. The maximum enhancement of light extraction efficiency of InGaN quantum well LEDs was achieved by employing the refractive index matched anatase-TiO2 microsphere arrays. The effects of microsphere diameters on the light extraction efficiency were also investigated and 2.4 times enhancement was achieved by employing 400-nm refractive index matched TiO2 sphere arrays.

Original languageEnglish (US)
Article number6477173
Pages (from-to)317-323
Number of pages7
JournalIEEE/OSA Journal of Display Technology
Issue number5
StatePublished - 2013
Externally publishedYes


  • III-nitride
  • light extraction efficiency
  • light-emitting diodes (LEDs)
  • matched refractive index
  • microspheres

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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