Reducing specific contact resistivity of V/Al/Ti/Au n-electrode on n-AlGaN with Al content over 80% for far-UVC LEDs

• Decreasing V thickness in V/Al/Ti/Au electrodes promotes Al diffusion to n-AlGaN surface, enhancing VN formation and local electron concentration, thereby reducing specific contact resistivity. • Increasing Al thickness inhibits Au diffusion to the n-AlGaN surface, suppressing Schottky barrier rise and further improving contact performance. • Optimized electrode stack V(10 nm)/Al(240 nm)/Ti(40 nm)/Au(50 nm) achieves a record-low specific contact resistivity of 7.30 × 10−4 Ω·cm2 on n-Al0.81Ga0.19N. • Application of the optimized n-electrode reduces the operating voltage of a 233.5 nm far-UVC LED, demonstrating practical viability.