GaN-Based Light-Emitting Diode With Three-Dimensional Silver Reflectors

We present a simple and robust method to fabricate three-dimensional Ag reflectors on GaN light-emitting diodes (LEDs) using SiO
₂
nanospheres as the template. First, the hexagonal arrays of SiO
₂
nanosphere monolayer were spun-cast on a benzocyclobutene (BCB) layer, which was prepared on a sapphire surface. Then, the bottom half of the SiO
₂
nanospheres were embedded into the BCB layer after heating, resulting in arrays of ldquonano-lensesrdquo that were in the shape of convex hemispheres. The concave-shaped hemisphere arrays were produced by etching the SiO
₂
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%.