Light Extraction Efficiency Improvement by Curved GaN Sidewalls in InGaN-Based Light-Emitting Diodes

Polygonal GaN sidewalls are fabricated using a laser scriber and a wet-etching process. After a two-step laser scribing process and a hot acid etching treatment, curved GaN sidewalls are formed consisting of the chemically stable (10-1-2) crystallographic plane of GaN epilayer and the laser-cutting facets. Compared to light-emitting diodes (LEDs) with vertical and inclined GaN sidewalls, light output power of LEDs with these curved GaN sidewalls exhibits an improvement of 10.2% and 6.8%, respectively. I-V curve shows that there is no deterioration to the curved-sidewall LEDs´ electronic properties. This enhancement of light output power is also confirmed by numerical simulations using the ray-tracing method.