Light extraction efficiency enhancement of deep ultraviolet light-emitting diodes using wafer-scale SiO2-based patterned dielectric nanostructures.

The progress of AlGaN-based deep ultraviolet light-emitting diodes is significantly limited by their unideal light extraction efficiency. In this work, a cost-efficient nanosphere lithography technique is utilized to fabricate wafer-scale SiO₂-based patterned dielectric nanostructures on the backside of sapphire substrates. Mapping results and statistical analyses demonstrate a uniform optical power enhancement across the entire chip, and the average power can be increased by 16.7% with almost identical peak wavelength and slightly enhanced operating voltage. The light output power of the LEDs with the patterned film exhibits a substantial enhancement of 34.0% compared to conventional LEDs at an injected current of 330 mA, accompanied by a 1.34-fold increase in light extraction efficiency. Finite-difference time-domain simulations indicate that the nanostructures on the patterned film effectively weakened total internal reflection at the sapphire/air interface. The above results validate the scalability of this method for industrial mass production of high-power DUV LEDs.