Effect of Inductively Coupled Plasma Etching Parameters on n-Al0.5Ga0.5N Ohmic Contact

High-Al-content n-AlGaN ohmic contact is very important for deep ultraviolet optoelectrical devices. However, it often suffers from the etching damages formed in inductively coupled plasma (ICP) etching. In this paper, the effects of ICP etching parameters on n-Al_0.5Ga_0.5N ohmic contact, including RF power, ICP power, and etching gas, were systematically investigated and analyzed by X-ray photoelectron spectroscopy and circular transmission line model. Finally, n-Al_0.5Ga_0.5N ohmic contact was achieved with a low specific contact resistivity of 8.7×10^-4 Ω·cm², and AlGaN-based UVC light-emitting diodes (LEDs) showed a low operation voltage of only 5.6 V at the injection current density of 16 A/cm².