Al₂O₃ powder coating and surface texturing for high efficiency GaN-based light emitting diodes

For high efficiency GaN-based light-emitting diodes (LEDs), Al ₂O₃ powder coating and surface texturing were investigated using natural lithography and dry-etching methods to improve the light-output power of the GaN-based LED. The 300-nm-size Al₂O₃ powder is coated on the indium tin oxide (ITO) surface at various conditions using a spin-coating method. The morphologies of the ITO surface were observed using a scanning electron microscope. The Al₂O₃ powder is left on the ITO surface after surface-texturing to increase extraction efficiency. The light output powers of the surface-textured GaN-based LEDs coated with the Al₂O₃ powders are enhanced by ∼66% compared with the conventional LED at 20 mA.