Enhanced light extraction in n-GaN-based light-emitting diodes with three-dimensional semi-spherical structure

Three-dimensional (3D) periodic micro/nanostructures can have a remarkable enhancement effect on light-emitting diodes (LEDs). However, simple, high-throughput and large-area fabrication of 3D periodic micro/nanostructures with a high duty ratio is difficult. In this Letter, high-duty-ratio 3D semi-spherical structures were fabricated on the surface of n-GaN-based vertical-structure LEDs by under-exposure ultraviolet lithography and dry etching. The resulting LEDs provide about 200% more light output power than those with a flat surface. This method of fabricating high-duty-ratio 3D semi-spherical structures could be used in other optical devices and shows potential for industrial production and commercialization. (C) 2014 AIP Publishing LLC.