Ohmic Contact Behavior of Carbon Films on SiC

We demonstrate ohmic contacts to SiC using carbon films after thermal annealing. Carbon films are deposited on 4H-SiC and 6H-SiC substrates using a radio frequency sputtering method. The carbon/SiC samples convert from Schottky behavior to ohmic behavior after annealing in the temperature range from 1150 to 1350°C. Nanosize graphitic flakes are identified after annealing by Raman spectroscopy and are associated with the ohmic behavior of the contacts. The contact behavior of carbon films on 4H-SiC and 6H-SiC after annealing are compared and the polytype of the SiC has no effects on the structural evolution of the carbon films during annealing. This study reveals that the structural evolution of carbon is associated with formation of ohmic contacts on SiC and that nanosize graphitic flakes play a determinative role in the formation of ohmic contacts. © 2003 The Electrochemical Society. All rights reserved.