Enhanced light extraction from GaN-based vertical light-emitting diodes with a nano-roughened N-GaN surface using dual-etch.

The effect of the dual-etch surface roughening method consisting of dry etching and wet etching on the enhancement of light extraction of vertical light emitting diodes (VLEDs) is investigated. The surface of a VLED was roughened by dry etching using SiO2 spheres as the mask while a KOH solution was used for wet etching. After the surface of the VLED was roughened by the dual-etch method, the luminous efficiency of the VLED increased due to the formation of uniform, nano-scale cone shapes and the decreased flat area ratio of the total GaN surface. The VLED roughened by dual etching showed about 9.3% higher emitted luminous efficiency than the VLED roughened using wet etching.