Study of GaN-based LEDs with hybrid SiO₂ microsphere/nanosphere antireflection coating as a passivation layer by a rapid convection deposition

A hybrid SiO₂ micro/nanospheres antireflection coating, deposited by a rapid convection deposition, acting as a passivation layer of GaN-based light-emitting diodes (LEDs) is studied in this paper. Since the critical angle could be enlarged by antireflection coating, Fresnel reflection could be reduced. In addition, due to the roughened surface of hybrid SiO₂ microsphere/nanosphere antireflection coating, the scattering effect could be increased. Thus, the light extraction efficiency could be further enhanced. As compared with a conventional LED (device A), at 20 mA, the studied device C exhibits 18.7% enhancement in light output power without any degradation of electrical properties. Reduced leakage current could also be achieved. Therefore, the use of hybrid SiO₂ microsphere/nanosphere antireflection coating could effectively improve the performance of GaN-based LEDs.