Electrical characterization of inhomogeneous Ni2Si/SiC Schottky contacts

The electrical characterization of nickel silicide (Ni2Si) Schottky contacts on 4H-SiC is reported in this work. In spite of the nearly ideal behaviour observed at room temperature (n=1.05), a deviation from the ideality was observed at lower temperatures, thus suggesting that an inhomogeneous Schottky barrier has actually formed. The experimental results were described by the Tung's model on inhomogeneous Schottky barriers, which considers low barrier regions embedded in a uniform high barrier Ni2Si contact. The inhomogeneity of the barrier is responsible of the commonly observed discrepancy between the experimental values of the Richardson's constant A** (i.e. 2.6 A/cm(2)K(2) in our contacts) from its theoretical value of 146 A/cm(2)K(2) in 4H-SiC.