Effects of annealing temperature on the degree of inhomogeneity of nickel-silicide/SiC Schottky barrier

The electrical characteristics of nickel-silicide Schottky contacts on silicon carbide have been measured by using current-voltage technique in the temperature range of 120-700 K. Thermal annealing at 873 K formed the nickel silicide. The electrical behavior of the contact showed a deviation from linearity at low temperatures. Annealing at high temperature (1223 K) produces deep modifications in the electrical characteristics at low bias and low temperatures, which are consistent with the formation of an inhomogeneous barrier. The description of the experimental results by using Tung''''s model [R. T. Tung, Phys. Rev. B 45, 13509 (1992)] allowed us to determine the values of the average barrier height of 1.62 and 1.14 eV for the diode annealed at 873 and 1223 K, respectively.