Ni-induced graphitization for enhanced long-term stability of ohmic contact to polycrystalline 3C-SiC

Stable metal contacts for SiC-based devices are required for high temperature microelectronics and microsensor devices. Ni-induced nanocrystalline graphitic carbon is introduced between Pt/Ti and n-type polycrystalline 3C-SiC as a means of forming contacts that are stable at high temperature. With the addition of an alumina protection layer, this metallization scheme is further improved and can maintain low contact resistivity after 500 h at 450 °C in air. The role of the graphitic layer in both the formation and long-term stability of the contact is investigated. Although the formation of an ohmic contact between Pt/Ti and polycrystalline 3C-SiC does not require the graphitic carbon, this interfacial layer is necessary for maintaining low contact resistivity during long-term exposure to elevated temperature.