Enhanced light output of GaN-based vertical light-emitting diodes with superimposed circular protrusions and hexagonal cones

A method was demonstrated for surface texturing through integrating ablation etching by KrF excimer laser irradiation and chemical wet etching designed to improve the light-extraction efficiency of vertically structured GaN-based light-emitting diodes (VLEDs). The fabricated VLEDs with the proposed surface roughening scheme exhibited an increase in light output power by 119.3 and 107% at 350 and 750 mA, respectively, as compared to that of the flat-VLEDs. Such improvements could be attributed to the proposed method that creates a twofold surface roughness to maximize the angular randomization of photons at the emission surface significantly increases the surface area of VLEDs.