Improvement of photon extraction efficiency of GaN-based LED using micro and nano complex polymer structures

• Published in: Nanoscale research letters Vol. 6; no. 1; p. 578
• Main Authors: Cho, Joong-Yeon, Byeon, Kyeong-Jae, Park, Hyoungwon, Kim, Jinseung, Kim, Hyeong-Seok, Lee, Heon
• Format: Journal Article
• Language: English
• Published: New York Springer New York 31-10-2011; BioMed Central Ltd; Springer; SpringerOpen
• Subjects: Chemistry and Materials Science; Materials Science; Molecular Medicine; Nano Express; Nanochemistry; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Light Extraction Efficiency; Lead Device; Total Internal Reflection; PDMS; External Quantum Efficiency
• ISSN: 1556-276X; 1931-7573; 1556-276X
• DOI: 10.1186/1556-276X-6-578

A micro- and nanoscale complex structure made of a high refractive index polymer (
n
= 2.08) was formed on the ITO electrode layer of an edge-emitting type GaN blue light-emitting diode (LED), in order to improve the photon extraction efficiency by suppressing total internal reflection of photons. The nanoimprint lithography process was used to form the micro- and nanoscale complex structures, using a polymer resin with dispersed TiO
2
nano-particles as an imprint resin. Plasma processing, such as reactive ion etching, was used to form the micro- and nano-scale complex structure; thus, plasma-induced damage to the LED device can be avoided. Due to the high refractive index polymeric micro- and nanostructure on the ITO layer, the electroluminescence emission was increased up to 20%, compared to an identical LED that was grown on a patterned sapphire substrate to improve photon extraction efficiency.