Richardson's constant in inhomogeneous silicon carbide Schottky contacts

The electrical characterization of nickel silicide Schottky contacts on silicon carbide (4H-SiC) is reported in this article. In spite of the nearly ideal behavior of the contact at room temperature (n=1.05), the electrical behavior monitored in a wide temperature range exhibited a deviation from the ideality at lower temperatures, thus suggesting that. an inhomogeneous barrier has actually formed. A description of the experimental results by the Tung's model, i.e., considering an effective area of the inhomogeneous contact, provided a procedure for a correct determination of the Richardson's constant A**. An effective area lower than the geometric area of the diode is responsible for the commonly observed discrepancy in the experimental values of A** from its theoretical value in silicon carbide. The same method was applied to Ti/4H-SiC contacts.