GaN-Based LEDs With Air Voids Prepared by Laser Scribing and Chemical Etching

The authors report the formation of air-voids at the GaN/cone-shaped-patterned-sapphire-substrate interface by laser scribing and lateral etching with one-step growth. With 5- and 20-min lateral etching, it was found that pyramid-like air-void was formed with an average height of 0.98 and 1.9 μm, respectively, on top of each corn of the substrate. It was also found that we can enhance output power of GaN-based light-emitting diodes by 6.6% and 11.5%, respectively, by immersing the wafer in a mixture of H ₃PO₄ and H ₂SO₄ solution at 220 ^°C for 5 and 20 min, respectively.