Enhanced light extraction of a high-power GaN-based light-emitting diode with a nanohemispherical hybrid backside reflector

A high-power GaN-based light-emitting diode (LED) with an inductively coupled plasma (ICP)-transferred nanohemispherical hybrid backside reflector is studied. A self-assembled 100 ± 5 nm SiO₂ nanosphere monolayer is drop-coated on the backside of a sapphire substrate as a mask to transfer nanohemispherical patterns onto the backside of the sapphire substrate by ICP. Nanohemispherical patterns could be transferred to the deposited backside reflector. Thus, reflected photons could be redirected and scattered into arbitrary directions for light extraction. As compared with a conventional LED without a backside reflector, at 350 mA, the studied device exhibits a 118.2% enhancement in light output power without the degradation of electrical properties. Note that the adhesion between an ICP-transferred sapphire substrate and the hybrid backside reflector is better than when directly inserting an SiO₂ nanosphere monolayer in the device. Thus, the process yield could be enhanced for applying in the solid-state lighting.