Influence of Al doping concentration and annealing parameters on TiAl based Ohmic contacts on 4H-SiC

TLM structures on Al-implanted regions with different implanted Al concentrations and different annealing temperatures were processed and characterized by electrical measurements in order to determine the influence of these parameters on the ohmic resistivity. Based on these results, a TCAD model was developed that considers the carrier concentration of the implanted region, the effective density of states for holes and the hole tunneling mass at the Ti3SiC2-SiC interface. It could be shown that Ti3SiC2 allows to form ohmic contacts on Al implanted samples with an effective doping concentration down to 3·1017 1/cm³. Furthermore the effective density of states for holes in Ti3SiC2 was determined to 8.5·1018 1/cm³ and the hole tunneling mass in SiC and Ti3SiC2 in the range of 2·10-34 kg to 6·10-33 kg depending on the sample.