Enhanced Light Extraction Efficiency of GaN-Based LED with ZnO Nanorod Grown on Ga-Doped ZnO Seed Layer

High density and narrow zinc oxide nanorod (ZnO NR) arrays (aspect ratio ∼18.9) were hydrothermally grown on gallium-doped ZnO (GZO) seed layer (3 wt% Ga-doping). Light-emitting diode (LED) fabricated with ZnO NR arrays grown on GZO seed showed marked 19% and 70% increases in light output power at 20 mA of driving current compared to that of LED with ZnO NR arrays grown on ZnO seed layer and reference LED. The significant enhancement of light output power is attributed to high density and surface-to-volume ratios of NR arrays as well as to enhanced multiple photons scattering at the NR surface.