Light-Extraction Enhancement of Large-Area GaN-Based LEDs With Electrochemically Grown ZnO Nanorod Arrays

We reported the improvement in light-extraction efficiency of large-area InGaN/GaN blue light-emitting diodes (LEDs) with zinc oxide (ZnO) nanorod arrays (NRAs), together with theoretical analysis. The ZnO NRAs with high transmittance were grown on the indium-tin-oxide surface with a thin Al-doped ZnO seed layer by electrochemical deposition. The vertically well-aligned ZnO NRAs exhibited an excellent suppression of internal reflections as well as a good transmittance. For LEDs with optimized ZnO NRAs, the light output power was improved by ~20% at 350 mA compared to that of the conventional LED.