Increased light extraction from vertical GaN light-emitting diodes with ordered, cone-shaped deep-pillar nanostructures

Ho Myoung An, Jae In Sim, Ki Seob Shin, Yun Mo Sung, Tae Geun Kim

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


In this paper, improved light extraction using cone-shaped deep-pillar nanostructures is demonstrated on the Honeycomb-type vertical GaN light-emitting diodes (VLEDs). In order to produce ordered, cone-shaped deep-pillar patterns on the surface of an n-type GaN, double-layered polystyrene (PS) nanospheres of 500-nm size were coated onto the n-GaN layer by a simple spin-coating. Then, immediately after the O 2 plasma ashing for double-layered PS beads, the Ni metal was deposited and lifted off to form a hard mask for deep pillar etching. Then, the three VLEDsthe reference VLED with no patterns and the two VLEDs with ordered, cone-shaped pillar patterns of 1.0 and 1.5 μ m depth on the n-type GaN surfacewere prepared for comparison. As a result, the output power for the proposed VLEDs with 1.0-and 1.5-μ m-deep cone-shaped patterns has been increased by 200% and 214%, respectively, at 350 mA as compared to the reference VLED. There was a slight sacrifice of operational voltage and leakage current. The improved optical properties are attributed to the multiple scattering of light from the sidewall of the cone-shaped patterns and the increased surface dimension.

Original languageEnglish
Article number6183454
Pages (from-to)891-896
Number of pages6
JournalIEEE Journal of Quantum Electronics
Issue number7
Publication statusPublished - 2012

Bibliographical note

Funding Information:
Manuscript received January 5, 2012; revised February 21, 2012; accepted March 6, 2012. Date of current version May 8, 2012. This work was supported in part by the National Research Foundation of Korea Grant funded by the Korean Government (MEST) under Grant 2011-0028769, the Technology Innovation Program (Industrial Strategic Technology Development Program, 10035430, Development of High Efficiency Light Emitting Diode for Illumination) funded by the Ministry of Knowledge Economy, Korea.

Copyright 2012 Elsevier B.V., All rights reserved.


  • Cone-shaped
  • Double layer coating
  • Gallium nitride
  • Honeycomb-type
  • Nanosphere lithography
  • Vertical light emitting diode

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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