Impact of Plasma Treatment of n-Al<sub>0.87</sub>Ga<sub>0.13</sub>N:Si Surfaces on V/Al/Ni/Au Contacts in Far-UVC LEDs
Hyun Kyong Cho, Jens Raß, Anna Mogilatenko, K. Kunkel, Ralph-Stephan Unger, Marcel Schilling, Tim Wernicke, S. Einfeldt
Abstract
We investigated the effect of treating the surface of n-Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.87</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.13</sub> N:Si by O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> or SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> plasma on the properties of subsequently deposited and annealed V/Al/Ni/Au contacts. Whereas an O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma treatment increases the contact resistivity, an SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> 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.