GaN-based light emitting diodes on nano-hole patterned sapphire substrate prepared by three-beam laser inter- ference lithography

Nano-hole patterned sapphire substrates （NHPSSs） were successfully prepared using a low-cost and high-efficiency approach, which is the laser interference lithography （LIL） combined with reactive ion etching （RIE） and inductively coupled plasma （ICP） techniques. Gallium nitride （GaN）-based light emitting diode （LED） structure was grown on NHPSS by metal organic chemical vapor deposition （MOCVD）. Photoluminescence （PL） measurement was conducted to compare the luminescence efficiency of the GaN-based LED structure grown on NHPSS （＇NHPSS-LED） and that on unpatterned sapphire substrates （UPSS-LED）. Electroluminescence （EL） measurement shows that the output power of NHPSS-LED is 2.3 times as high as that of UPSS-LED with an injection current of 150 mA. Both PL and EL results imply that NHPSS has an advantage in improving the crystalline quality of Gab/epilayer and light extraction efficiency of LEDs at the same time.