Enhancement of light extraction efficiency of GaN-based light-emitting diode using ZnO sol-gel direct imprinting

Seong Hwan Lee, Kyeong Jae Byeon, Hyoungwon Park, Joong Yeon Cho, Ki Yeon Yang, Heon Lee

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


ZnO nano-structures were formed on transparent conducting oxide layer of GaN LED device on non-patterned (non-PSS) and patterned sapphire substrates (PSS). Since ZnO nano-structures were formed by sol-gel direct imprinting process, plasma etching process, which may create the plasma induced damage, was not used. Due to the ZnO nano-structures, light extracted from active layer was coupled with ZnO nano-structures and thus total internal reflection at the ITO layer was suppressed. According to electroluminescence measurement, the emission intensities of GaN LED devices with ZnO nano-structures, on both non-PSS and PSS sapphire substrates were increased by 20.5% and 19.0%, respectively, compared to GaN LED devices without ZnO nano-structures, due to the suppression of total internal reflection. Moreover, it is confirmed that there is no decrease of light extraction on side direction due to light focusing to vertical axis by nanostructure. Electrical performance of GaN LED devices were not degraded by ZnO sol-gel direct imprinting process.

Original languageEnglish
Pages (from-to)3278-3281
Number of pages4
JournalMicroelectronic Engineering
Issue number11
Publication statusPublished - 2011 Nov

Bibliographical note

Funding Information:
This work is the outcome of a Manpower Development Program for Energy and Resources supported by the Ministry of Knowledge and Economy (MKE). This work was partly supported by the IT R&D program of MKE/IITA ( 2009-F-025-01 , Development of Core Technology for High Efficiency Light Emitting Diode based on New Concepts).


  • EL measurement
  • Light emitting diode
  • Light extraction efficiency
  • PSS substrate
  • Sol-gel direct imprinting
  • ZnO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering


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