GaN-based light emitting diodes with large area surface nano-structures patterned by anodic aluminum oxide templates

We demonstrate a manufacturing approach of nanostructures on the large surface area of GaN-based LED chip to improve the light extraction efficiency. We prepared the nanoporous anodic aluminum oxide (AAO) template on an aluminum foil by the conventional two-step anodization. Using the AAO template as etching mask, we successfully transferred the nanoporous structures to the surfaces of GaN-based LEDs by inductively coupled plasma dry etching. About a quarter of two-inch GaN-based LED chip was patterned by the nanostructures. The pore spacing was modulated from 100 nm to 400 nm. The improvement of light extraction efficiency of the device was achieved. A light output power enhancement of 42% was obtained from the p-side surface nanopatterned LEDs compared to the conventional LEDs on the same wafer at 20 mA. This approach offers a potential technique of nanostructures fabrication on GaNbased LEDs with the advantages of large area, rapid process and low cost.