Enhancement of near-UV GaN LED light extraction efficiency by GaN/sapphire template patterning

Abstract

We present near-UV GaN light-emitting diodes (LEDs) grown on patterned GaN/sapphire templates with improved material quality and light extraction efficiency. Enhancement of light extraction efficiency is attributed to voids generated at the GaN/sapphire interface. The sidewall inclination angle of the voids can be controlled from nearly vertical (∼ 85°) to fully inclined (∼ 60°) by changing the initial patterning dimensions. Light extraction efficiency and material quality improve with a decreasing void sidewall angle. A 20% increase in the light output is observed at 20 mA of input current for LED structures with ∼60° inclined sidewall voids.