Analysis of light extraction efficiency enhancement for InGaN quantum wells light-emitting diodes with microspheres

Peng Zhao, Xuechen Jiao, Hongping Zhao

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther

3 Citations (Scopus)


The enhancement of light extraction efficiency for thin-film flip-chip (TFFC) InGaN quantum wells (QWs) light-emitting diodes (LEDs) with self-assembled microspheres on top of the n-GaN layer was studied. The light extraction efficiency of InGaN QWs LEDs for the three structures with 1) close-packed SiO 2 microlens; 2) close-packed SiO 2 / polystyrene microlens; and 3) GaN micro-hemispheres were calculated and compared to that of the conventional InGaN QWs LEDs with flat surface. Three dimensional finite difference time domain (3D-FDTD) method was used to calculate the light extraction efficiency for TFFC InGaN/GaN QWs LEDs emitting at 460nm. The effects of the microsphere/micro-hemisphere diameter and the p-GaN layer thickness on the light extraction efficiency were studied. Studies show that the p-GaN layer thickness is critical for optimizing the TFFC LED light extraction efficiency. Light extraction efficiency enhancement of 1.7 times and 1.85 times were obtained in the TFFC LEDs with SiO 2 microlens and SiO 2 /polystyrene microlens, respectively. More significant enhancement of the light extraction efficiency (>2.6 times) was achieved from LEDs with GaN micro-hemispheres with optimized micro-hemisphere diameter of D=1μm and p-GaN thickness of 195nm.

Original languageEnglish
Title of host publication2012 IEEE Energytech, Energytech 2012
Publication statusPublished - 12 Nov 2012
Externally publishedYes
Event2012 IEEE Energytech, Energytech 2012 - Cleveland, OH, United States of America
Duration: 29 May 201231 May 2012

Publication series

Name2012 IEEE Energytech, Energytech 2012


Conference2012 IEEE Energytech, Energytech 2012
Country/TerritoryUnited States of America
CityCleveland, OH


  • finite difference time domain
  • InGaN quantum wells
  • light extraction efficiency
  • Light-emitting diodes
  • self-assembled microspheres
  • thin-film flip-chip (TFFC)

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