A computational design of AlGaN-based deep ultraviolet photonic crystal light-emitting diodes by tuning the band-edge resonance

Abstract

We propose a photonic crystal (PhC) design strategy for AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) using either air–hole or nanowire arrays to simultaneously enhance light extraction efficiency (LEE) and to enable vertical emission directionality. By selecting resonant modes at the Γ point and engineering their electric field distributions to avoid spatial overlap with the absorptive p-GaN contact layer, optical absorption is effectively suppressed. Both air–hole and nanowire photonic crystal structures generate vertical light emission through band-edge mode at the Γ point. The LEE of the air–hole configuration reached up to 56.5%, while that of the nanowire design reaches up to 76.1%, significantly outperforming conventional planar LEDs. Considering the reduced area of the active region in photonic crystals, the effective LEE is defined to evaluate the overall performance, evidencing the advantages of both the air–hole and the nanowire structures over the planar counterpart. By replacing the absorptive p-type GaN contact layer with a transparent p-type material, such as Al0.65Ga0.35N or h-BN, both photonic crystal designs exhibit much higher LEE boost compared to the planar counterpart. These results establish an effective approach to overcome the dual challenges of total internal reflection and light absorption in DUV LEDs.