Improvement of high temperature stability of nickel contacts on n-type 6H–SiC

Abstract

The structural and electrical characterisation of nickel contacts on n-type silicon carbide was performed to improve the ohmic behaviour at high temperatures. The formation of nickel silicide (Ni 2Si) was observed after annealing in vacuum of Ni/SiC samples at 600 °C, as well as after rapid thermal annealing (RTA) in N 2 at 700 for 60 s. The carbon was almost uniformly distributed inside the Ni 2Si layer, as monitored by energy dispersion X-ray analysis (EDX). The specific contact resistance ρ c was determined by the transmission line method (TLM) for different values of the substrate carrier concentration N D. Ohmic contacts with ρ c =3.9×10 −5 Ω cm 2 were obtained for substrates with N D =7.4×10 18 cm −3 after RTA in N 2 at 950 °C. The optimised contacts maintain their electrical stability even after annealing in N 2 up to 1000 °C.