Post-removal for the deposited Au metal to increase the light extraction efficiency for AlGaN-based deep-ultraviolet light-emitting diodes

Ni/Au is employed to ensure a high-quality p-type ohmic contact for most AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs). However, the substantial absorptivity of ultraviolet light by Ni/Au significantly impacts the light extraction efficiency (LEE). In this work, to reduce the absorptivity of a Ni/Au electrode, we conduct wet-etching to the Ni/Au electrode after the formation of ohmic contact between Ni/Au and p-AlGaN. Experimental results show that the optical transmittance of the Ni/Au electrode can be improved from 35.2% to 42.68% after the Ni/Au is wet- etched for 5 min. When compared with the reference device, the optical power and the wall plug efficiency (WPE) of the proposed device are enhanced by 10.24% and 9.89% at an injection current of 100 mA, respectively. Although the proposed DUV LED exhibits a 0.30 V increase in forward voltage, this does not affect the device's stability after making a 1000-h lifetime test. This proposed method not only can improve the LEE but also is fully compatible with the mass production of DUV LEDs. (c) 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.