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

We have synthesized Ti–Si–C nanocomposite thin films by dc magnetron sputtering from a ${\mathrm{Ti}}_3\mathrm{Si}{\mathrm{C}}_2$ compound target in an Ar discharge on Si(100), ${\mathrm{Al}}_2{\mathrm{O}}_3\left(0001\right)$ , and Al substrates at temperatures from room temperature to $300°\mathrm{C}$ . Electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy showed that the films consisted of nanocrystalline $\left(\mathit{nc}\text{-}\right)$ TiC and amorphous $\left(a\text{-}\right)$ 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 $290\mathrm{GPa}$ , respectively. The electrical resistivity was $330\mu \Omega \mathrm{cm}$ for optimal Ar pressure $\left(4\mathrm{mTorr}\right)$ and substrate temperature $(300°\mathrm{C})$ . The resulting $\mathit{nc}\text{-}\mathrm{Ti}\mathrm{C}∕a\text{-}\mathrm{Si}\mathrm{C}$ films performed well as electrical contact material. These films’ electrical-contact resistance against Ag was remarkably low, $6\mu \Omega$ at a contact force of $800\mathrm{N}$ compared to $3.2\mu \Omega$ for Ag against Ag. The chemical stability of the $\mathit{nc}\text{-}\mathrm{Ti}\mathrm{C}∕a\text{-}\mathrm{Si}\mathrm{C}$ 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.