GaN-based light-emitting diodes with step graded-refractive index (ZnO x(SiO2)1-x micropillar array

Hung Ming Chang, Ya Yu Yang, Wei Chi Lai, Shuguang Li, Yu Ruh Lin, Zhi Yong Jiao, Shoou Jinn Chang

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Step graded-refractive index (SGRI) (ZnO)x(SiO2) 1-x micropillar multilayers have been introduced and demonstrated on GaN-based LEDs combined with the mesh ITO. The SGRI (ZnO)x(SiO 2)1-x micropillars were produced by controlling the Zn/Zn+Si ratio of co-sputtered ZnO and SiO2. The introduced three-layered SGRI (ZnO)x(SiO2)1-x micropillars improved both critical angle inside GaN LEDs and Fresnel transmittance coefficient (ηFr) as well as had better light coupling into the micropillars. Moreover, a high number of layers of the SGRI micropillars would aid the light coupled in the pillars to escape from the side wall of the pillar. LEDs with three-layered SGRI (ZnO)x(SiO2)1-x micropillars exhibited output power enhancements of 12.2% with a 20 mA V f of 3.19 V. The output power of the mesh ITO LEDs with SGRI (ZnO)x(SiO2)1-x micropillars was further enhanced to 15.3% by improving the current spreading.

Original languageEnglish
Article number6308728
Pages (from-to)353-358
Number of pages6
JournalIEEE/OSA Journal of Display Technology
Issue number5
Publication statusPublished - 2013

All Science Journal Classification (ASJC) codes

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

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