We present a simple and robust method to fabricate three-dimensional Ag reflectors on GaN light-emitting diodes (LEDs) using SiO2 nanospheres as the template. First, the hexagonal arrays of SiO2 nanosphere monolayer were spun-cast on a benzocyclobutene (BCB) layer, which was prepared on a sapphire surface. Then, the bottom half of the SiO2 nanospheres were embedded into the BCB layer after heating, resulting in arrays of "nano-lenses" that were in the shape of convex hemispheres. The concave-shaped hemisphere arrays were produced by etching the SiO2 nanospheres with an HF solution. Ag was deposited onto both patterns, concave and convex hemispheres, resulting in the formation of three-dimensional Ag reflectors. From the electroluminescence measurements, these Ag reflectors, which contained either concave or convex hemisphere patterns, were found to enhance the light output of GaN LEDs by as much as 29%-33%.
Bibliographical noteFunding Information:
Manuscript received January 13, 2009; revised February 21, 2009. First published March 16, 2009; current version published May 08, 2009. This work was supported by the Carbon Dioxide Reduction and Sequestration Center, a 21st Century Frontier R&D Program funded by the Ministry of Education, Science and Technology of Korea.
- Light extraction efficiency
- Light-emitting diodes (LEDs)
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering