Impact of Plasma Treatment of n-Al0.87Ga0.13N:Si Surfaces on V/Al/Ni/Au Contacts in Far-UVC LEDs

We investigated the effect of treating the surface of n-Al
_0.87
Ga
_0.13
N:Si by O
₂
or SF
₆
plasma on the properties of subsequently deposited and annealed V/Al/Ni/Au contacts. Whereas an O
₂
plasma treatment increases the contact resistivity, an SF
₆
plasma treatment decreases it. The operating voltage of far-UVC LEDs emitting at 233 nm could thus be reduced by 2.2 V for a current of 50 mA. The results underline the detrimental impact of oxygen on the formation of low-resistance contacts on n-AlGaN surfaces with high Al mole fraction.