Au-free V/Al/Pt Contacts on n-Al_0.85Ga_0.15N:Si Surfaces of Far-UVC LEDs

The feasibility of replacing the V/Al/Ni/Au contact on n-Al 0.85 Ga 0.15 N:Si commonly used in far-UVC LEDs with a Au-free V/Al/Pt contact has been investigated. It is shown that the V and Pt layer thicknesses play an important role for achieving a low contact resistivity and a smooth contact surface at a low annealing temperature. The specific contact resistivity of V(10 nm)/Al(120 nm)/Pt(40 nm) annealed at 700 °C for 5 min is comparable with that of V(15 nm)/Al(120 nm)/Ni(20 nm)/Au(30 nm) annealed at 850 °C for 30 s. Furthermore, the root mean square roughness of the optimized V/Al/Pt contacts was 8.3 nm as compared to 30 nm for V/Al/Ni/Au.