A surface roughening scheme with Si3N4-coated GaN nanowire (NW) arrays is proposed to improve the light extraction efficiency of GaN-based vertical light-emitting diodes (VLEDs). The scheme allows a graded refractive index that varies from 2.5 (GaN) to 1.9-2.0 (Si3N 4) to 1 (air). Experimental results show that the use of 0.8-μm-long GaN NW arrays coated with a 250-nm-thick Si3N 4 film enhances the light output power by 28.7% at 350mA compared with that of regular VLEDs with a KOH-roughened surface. This enhancement is attributed to the Si3N4/GaN NW arrays effectively releasing total internal reflection and minimizing Fresnel loss.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)