Phase Inhomogeneity and Electrical Characteristics of Nickel Silicide Schottky Contacts Formed on 4H-SiC

Nikitina, I; Vassilevski, K; Horsfall, A; Wright, N; O'Neill, AG; Ray, SK; Johnson, CM

doi:10.4028/www.scientific.net/MSF.615-617.577

Phase Inhomogeneity and Electrical Characteristics of Nickel Silicide Schottky Contacts Formed on 4H-SiC

Lookup NU author(s): Irina Nikitina, Dr Konstantin Vasilevskiy ORCiD, Dr Alton Horsfall, Professor Nick Wright, Professor Anthony O'Neill, Dr Christopher Johnson

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Abstract

Nickel silicide Schottky contacts were formed on 4H-SiC by consecutive deposition of a titanium adhesion layer, 4 nm thick, and nickel, 100 nm thick. followed by annealing, at temperatures from 600 to 750 degrees C. It was found that contacts with barrier heights of 1.45 eV, consisting mainly of NiSi phase, formed in the 600-660 degrees C temperature range, while annealing at around 750 degrees C led to the formation of Ni2Si phase with barrier heights of 1.1 eV. Annealing at intermediate temperatures resulted in the nucleation of Ni2Si grains embedded in the NiSi film which were directly observed by micro-Raman mapping. It was concluded that the thermodynamically unfavourable NiSi phase appeared in the 600-660 degrees C temperature range due to the fact that the solid state chemical reaction between Ni and SiC at these temperatures is controlled by nickel diffusion through the titanium barrier.