LAUSR

Previous studies showed that cobalt silicide can form ohmic contacts to p-type 6H-SiC by directly reacting cobalt with 6H-SiC. Similar results can be achieved on 4H-SiC, given the similarities between the different silicon carbide polytypes. However, previous studies using multilayer deposition of silicon/cobalt on 4H-SiC gave ohmic contacts to n-type. In this study, we investigated the cobalt silicide/4H-SiC system to answer two research questions. Can cobalt contacts be self-aligned to contact holes to 4H-SiC? Are the self-aligned contacts ohmic to n-type, p-type, both or neither? Using x-ray diffraction, it was found that a mixture of silicides ($$\hbox {Co}_2\hbox {Si}$$Co2Si and CoSi) was reliably formed at 800$$^\circ $$∘C using rapid thermal processing. The cobalt silicide mixture becomes ohmic to epitaxially grown n-type ($$1\times 10^{19} \hbox {cm}^{-3}$$1×1019cm-3) if annealed at 1000$$^\circ $$∘C, while it shows rectifying properties to epitaxially grown p-type ($$1\times 10^{19} \hbox {cm}^{-3}$$1×1019cm-3) for all tested anneal temperatures in the range 800–1000$$^\circ $$∘C. The specific contact resistivity ($$\rho _\mathrm{C}$$ρC) to n-type was $$4.3 \times 10^{-4}$$4.3×10-4 $$\mathrm {\Omega }$$Ω$$\,\hbox {cm}^{2}$$cm2. This work opens the possibility to investigate other self-aligned contacts to silicon carbide.