Characterization of Ohmic Ni/Ti/Al and Ni Contacts to 4H-SiC from -40°C to 500°C

Extreme temperature measurements of Ni/Ti/Al contacts to p-type SiC (Na = 1∙1018cm-3), with a specific contact resistivity ρc = 6.75∙10-4 Ωcm2 at 25 °C, showed a five time increase of the specific contact resistivity at -40 °C (ρc = 3.16∙10-3 Ωcm2), and a reduction by almost a factor 10 at 500 °C (ρc = 7.49∙10-5 Ωcm2). The same response of ρc to temperature was seen for contacts on lower doped epitaxial layer. Also N-type nickel contacts improved with higher operational temperature but with a considerably smaller variation over the same temperature interval. No degradation of the performance was seen to either the Ni/Ti/Al or the Ni contacts due to the high temperature measurements.