Ohmic contacts to n-type polycrystalline SiC for high-temperature micromechanical applications

Highly doped n-type polycrystalline 3C-SiC films were examined for further use in high-temperature applications. The specific contact resistance of TiW contacts was determined using the circular transmission line method by Marlow and Das. The TiW-SiC interface was investigated by means of auger electron spectroscopy (AES) depth-profiles and atomic force microscopy (AFM) surface scans. In addition n-type 6H-SiC was used for reference purposes. It was found that these polycrystalline films were extremely rough (up to 70 nm) and therefore have a wide metal SiC interface, so that no certain statement about interface reaction could be made. The reference samples showed no interface reaction. TiW shows a good ohmic contact behaviour with a specific contact resistance of ρc = 7.8 × 10−5 Ω cm2 to polycrystalline 3C-SiC and with a ρc = 3.4 × 10−4 Ω cm2 to 6H-SiC.