We fabricated high-brightness GaN-based light-emitting diodes (LEDs) with highly refractive patterned structures by using a thermal nanoimprint lithography (NIL). A highly refractive ZnO-nanoparticle-dispersed resin (ZNDR) was used in NIL, and a submicron hole, a submicron high-aspect-ratio pillar, and microconvex arrays were fabricated on the indium tin oxide (ITO) top electrode of GaN-based LED devices. We analyzed the light extraction mechanism for each of the three types of patterns by using a finite element method simulation, and found that the high-aspect-ratio pillar had a great ability to improve light extraction owing to its waveguide effect and prominent scattering effect. As a result, the light output power, which was measured in an integrating sphere, of the LED device was enhanced by up to 19.6% when the high-aspect-ratio pillar array was formed on the top ITO electrode of the device. Further, the electrical properties of none of the patterned LED devices fabricated using ZNDR degraded in comparison to those of bare LED devices.
Bibliographical noteFunding Information:
This research was supported by the Nano Material Technology Development Program through the National Research Foundation of Korea (NRF) , funded by the Korean Ministry of Education, Science and Technology ( 2012M3A7B4035323 ) and LG Innotek—Korea University Nano-Photonics Program.
© 2015 Elsevier B.V. All rights reserved.
- Light extraction efficiency
- Light-emitting diodes (LEDs)
- Nanoimprint lithography (NIL)
- ZnO-nanoparticle-dispersed resin (ZNDR)
ASJC Scopus subject areas
- General Chemistry
- Condensed Matter Physics
- General Physics and Astronomy
- Surfaces and Interfaces
- Surfaces, Coatings and Films