Fabrication of photonic crystal structure on indium tin oxide electrode of GaN-based light-emitting diodes

Wafer-scale UV nanoimprint and dry etching processes were used to fabricate photonic crystal patterns on an indium tin oxide (ITO) top electrode of GaN-based green light-emitting diodes (LEDs). Photonic crystal patterns with pitches ranging from 600 to 900 nm were transferred to the entire 2-inch LED wafer. Plasma damage in the GaN crystal of the LED device was avoided because the GaN was covered by ITO layer and was not exposed to the etching plasma during the ITO dry etching process. Consequently, the electroluminescence intensity of the patterned LED devices was enhanced up to 25% at 20 mA of driving current, compared to the nonpatterned LED device, while the forward voltage was similar.