The diffusion of carbon and five other elements in amorphous carbon (a-C) films was studied. One set of samples were sp2 dominated a-C and the other set of samples were sp3dominated tetrahedral amorphous carbon (ta-C). The films were deposited using mass separated ion beam deposition under UHV conditions. The diffusion of 13C as well as that of hydrogen and deuterium was studied using high resolution elastic recoil detection analysis. No apparent self-diffusion could be detected using this technique. The diffusion of hydrogen was found to start at temperatures between 600 and 800C. For deuterium, activation energies of 3.34 and 3.39eV were found for diffusion in tetrahedral amorphous C and a-C, respectively. Tungsten, copper and silver were used to study the diffusion of metals in tetrahedral amorphous C. Up to annealing temperatures of 1000C no diffusion took place in the samples. During annealing at 1200C the tetrahedral amorphous C was converted into graphite, making diffusion into the carbon matrix possible. The fact that there was no diffusion of copper in tetrahedral amorphous C at temperatures below 1200C showed that tetrahedral amorphous C was a possible diffusion barrier between copper and silicon.

Diffusion in Diamond-Like Carbon. Kröger, H., Ronning, C., Hofsäss, H., Neumaier, P., Bergmaier, A., Görgens, L., Dollinger, G.: Diamond and Related Materials, 2003, 12[10-11], 2042-50