Improvement in light-output efficiency of near-ultraviolet InGaN-GaN LEDs fabricated on stripe patterned sapphire substrates

InGaN/GaN multi-quantum wells near ultraviolet light-emitting diodes (LEDs) were fabricated on a patterned sapphire substrate (PSS) with parallel stripe along the 〈11¯00〉sapphire direction by using low-pressure metal-organic chemical vapor deposition (MOCVD). The forward- and reverse-bias electrical characteristics of the stripe PSS LEDs are, respectively, similar and better than those of conventional LEDs on sapphire substrate. The output power of the epoxy package of stripe PSS LED was 20% higher than that of the conventional LEDs. The enhancement of output power is due not only to the reduction of dislocation density but also to the release of the guided light in LEDs by the geometric shape of the stripe PSS, according to the ray-tracing analysis.