Electrical characterization of TiC ohmic contacts to aluminum ion implanted 4H-silicon carbide

We report on the investigation of epitaxial TiC ohmic contacts to Al ion implanted 4H-SiC. TiC ohmic contacts were formed by coevaporation of Ti and C-60 at low temperature (< 500 degrees C). A sacrificial silicon nitride (Si3N4) layer was deposited on the silicon carbide substrate prior to Al implantation in order to reach a high Al dopant concentration at the surface while maintaining a low dose. The combination of epitaxially grown TiC and the silicon nitride layer resulted in a promising scheme to make low resistivity ohmic contacts. The lowest contact resistivity (rho(C)) and sheet resistance (R-s) of the implanted layer at 25 degrees C were as low as 2 x 10(-5) Ohm cm(2) and 0.6 k Ohm/square, respectively. (C) 2000 American Institute of Physics. [S0003-6951(00)01036-6].