Swift heavy ion irradiation of metal containing tetrahedral amorphous carbon films

• ta-C films with Ni and Cu doping were grown using dual cathode filtered vacuum arc deposition.
• Conductive channels were found in the films by C-AFM after irradiation with 100 MeV Ag ions.
• SEM contrast found after irradiation strongly depends on kind of metal impurity in the film.
• Different chemical effect of Ni and Cu on transformation of carbon matrix under irradiation was revealed.

Thin carbon films were grown at room temperature on (0 0 1) n-Si substrate using dual cathode filtered vacuum arc deposition system. Graphite was used as a source of carbon atoms and separate metallic electrode was simultaneously utilized to introduce Ni or Cu atoms. Films were irradiated by 100 MeV Ag7+ ions to fluences in the range 1 × 1010–3 × 1011 cm−2. Rutherford backscattering spectroscopy, Raman scattering, scanning electron microscopy and atomic force microscopy in conductive mode were used to investigate film properties and structure change under irradiation. Some conductive channels having metallic conductivity type were found in the films. Number of such channels is less than number of impinged ions. Presence of Ni and Cu atoms increases conductivity of those conductive channels. Fluence dependence of all properties studied suggests different mechanisms of swift heavy ion irradiation-induced transformation of carbon matrix due to different chemical effect of nickel and copper atoms.