Light extraction enhancement of InGaN light-emitting diode by roughening both undoped micropillar-structure GaN and p-GaN as well as employing an omnidirectional reflector

Light extraction enhancement of InGaN–GaN light-emitting diode (LED) is demonstrated with double-side roughening both on the p-GaN surface and the micropillar undoped GaN as well as an omnidirectional reflector via patterning sapphire substrate, wafer-bonding, laser lift-off, and chemical wet etching technologies. This device design enhances the light output power up to 77% compared to the conventional LED with a single roughened p-GaN on patterned sapphire substrate at an injection current of 350mA. Due to the employment of Si carrier, the junction temperature measurement at 350mA yields a 46.6°C lower than that of the conventional LEDs.