Enhancing the p-type ohmic contact characteristics of deep ultraviolet light-emitting diodes through an Au sacrificial layer without deteriorating the reflectivity

Improving the wall-plug efficiency (WPE) of AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) requires the optimization of both the p-type ohmic contact and the reflectivity, which remains a significant challenge. In this study, we employ a simple and effective Au-sacrificial-layer process, achieving the lowest specific contact resistivity of 6.1 × 10 −6 Ω·cm² for the Ni/Rh/Ni/Au contact on p-GaN—6 times reduction compared to the reference device. This approach enhances the p-type ohmic contact via Ga vacancies generated by the annealed Au layer, while the wet-etching reduces optical absorption to preserve the high reflectivity of the p-contact. The DUV LEDs fabricated with the 10-nm Au-sacrificial-layer process exhibit 0.69 V reduction in operating voltage and 15.54% enhancement in WPE at an injection current of 100 mA, compared to the reference device. This research provides a cost-effective strategy to improve the WPE of mass-produced AlGaN-based DUV LEDs.