Current-Induced Degradation of Nickel Ohmic Contacts to SiC

The stability of Ni ohmic contacts to p-type SiC under high current density was investigated. A test structure adapted from the four circular contacts method allowed for vertical stressing and the ability to extract a pre- and post-stressed specific contact resistance. The accuracy of the measured specific contact resistance was verified experimentally through comparisons with more widely used methods and the use of computer modeling. The growth of voids initially produced during the high-temperature ohmic contact anneal was found to be the degradation mechanism, effectively decreasing the area of the contact.