Improvement of light extraction efficiency in GaN-based light emitting diodes by random pattern of the p-GaN surface using a silica colloidal mask

A two-dimensional silica colloidal particle was used to etch a p-GaN surface. By treating the p-GaN surface with polyelectrolyte (PE), mono-dispersed silica colloidal particles, 500 nm in diameter, could be uniformly distributed on a 2-in. p-GaN surface. The patterns on the p-GaN surface were produced by a plasma etching process using these colloidal particles as a mask. Etching depths of 150 and 200 nm were produced on the p-GaN surface of LED samples and an increase in the optical output power of 46.7% was observed compared to a reference sample without patterns on the p-GaN surface.