Schottky-ohmic transition in nickel silicide/SiC-4H system: is it really a solved problem?

The transition from Schottky to ohmic contact in the nickel silicide/SiC system during annealing from 600 to 950 degreesC was investigated by measuring the electrical properties of the contact and by analyzing the microstructure of the silicide/SiC interface. The graphite clusters formed by carbon atoms during silicidation are uniformly distributed into the silicide layer after annealing at 600 degreesC and they agglomerate into a thin layer far from the silicide/SiC interface after annealing at 950 degreesC. At this temperature an increase of the Schottky barrier height was measured, while deep level transient spectroscopy evidences the absence of the 0.5 eV peak related to the carbon vacancies. (C) 2003 Elsevier B.V.. All rights reserved.