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Electrical properties and microstructure of V/Al/Ni/Au contacts on n-Al0.65Ga0.35N:Si with different Au thicknesses and annealing temperature

H.K. Cho1, A. Mogilatenko1, N. Susilo2, I. Ostermay1, S. Seifert1, T. Wernicke2, M. Kneissl1,2 and S. Einfeldt1

Published in:

Semicond. Sci. Technol., vol. 37, no. 10, pp. 105016, doi:10.1088/1361-6641/ac8e8f (2022).

Abstract:

We investigated the formation of ohmic contacts as a result of intermetallic phase formation between V, Al, Ni, and Au in V/Al/Ni/Au metal stacks on n-Al0.65Ga0.35N:Si. In particular, the influence of Au metal thickness and annealing temperature was analysed. The lowest annealing temperature of 750°C for an ohmic contact with a smooth surface and a contact resistivity of about 2.4 × 10-5 Ωcm2 was achieved for V(15 nm)/Al(120 nm)/Ni(20 nm)/Au(40 nm). The lowest contact resistivity is accompanied by formation of two thin interfacial regions consisting of AlN and an Au-rich phase. We suggest that not only the formation of thin interfacial AlN layer is important for a low contact resistance, but also the formation of the Au-rich interface can have a favourable effect on the contact properties.

1 Ferdinand-Braun-Institut, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany
2 Technische Universität Berlin, Institute of Solid State Physics, Hardenberg-Str. 36, 10623 Berlin, Germany

Keywords:

ohmic contact, n-AlGaN, high Al mole fraction, UV LED, Au rich phase, AlN

© 2022 The Author(s). Published by IOP Publishing Ltd.
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