Structural, electrical, and mechanical properties of nc-TiC/a-SiC nanocomposite thin films

摘要

We have synthesized Ti-Si-C nanocomposite thin films by dc magnetron sputtering from a Ti_3SiC_2 compound target in an Ar discharge on Si(100), Al_2O_3(0001), and Al substrates at temperatures from room temperature to 300℃. Electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy showed that the films consisted of nanocrystalline (nc-) TiC and amorphous (a-) SiC, with the possible presence of a small amount of noncarbidic C. The growth mode was columnar, yielding a nodular film-surface morphology. Mechanically, the films exhibited a remarkable ductile behavior. Their nanoindentation hardness and E-modulus values were 20 and 290 GPa, respectively. The electrical resistivity was 330 μΩ cm for optimal Ar pressure (4 mTorr) and substrate temperature (300℃). The resulting nc-TiC/a-SiC films performed well as electrical contact material. These films' electrical-contact resistance against Ag was remarkably low, 6 μΩ at a contact force of 800 N compared to 3.2 μΩ for Ag against Ag. The chemical stability of the nc-TiC/a-SiC films was excellent, as shown by a Battelle flowing mixed corrosive-gas test, with no N, Cl, or S contaminants entering the bulk of the films.