We prepared Ni and Ni2Si Schottky contacts on lightly doped (5.5 x 10(15) cm(-3)) n-type 6H-SiC and evaluated their thermal degradation after annealing in the temperature range of 750-1150 degrees C. Ni contacts had Schottky behavior after annealing at 750 and 850 degrees C; they gradually degraded at 960 and 1065 degrees C, and achieved ohmic behavior at 1150 degrees C. Ni2Si contacts had higher values of saturation current density and lower Schottky barrier heights than Ni contacts after annealing at 750 and 850 degrees C, and an abrupt transition from Schottky behavior at 850 degrees C to ohmic behavior at 960 degrees C. We assume that the abrupt transition from Schottky to ohmic behavior in the case of Ni2Si metallization is caused by its low reactivity with silicon carbide, which was verified by XPS depth profiling. The results indicate that the discrepancy in the behavior of Ni contacts on lightly doped SiC reported in the literature might have been caused by non-equal processing or by inaccurate determination of the annealing temperature. (c) 2010 Elsevier B. V. All rights reserved.