| Annealing up to 1300K of metal-doped (Ti, V, W, Zr) amorphous carbon layers with metal content up to 20 at.% leads to carbide formation and grain growth (several nm). Composition, distribution, and diffusion of the metal in the carbon were investigated by Rutherford backscattering spectroscopy (RBS), showing homogeneity laterally and in depth and diffusion in a neighbouring a-C film of less than 20 nm. The layer and surface morphology was examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), and profilometry. X-ray absorption spectroscopic (XAS) analysis have shown how the local atomic environment of the metal and carbon was affected by thermal treatment up to 1300K from amorphous non-metallic bonding to carbidic ordering. The grain sizes obtained from X-ray diffraction (XRD) varied from 2 nm for W to 9 nm for V after annealing at 1300K. The experimental boundary conditions of film thickness (200-1800 nm) and substrate (Si, SiC, Cu) were varied to quantify the film hardness. The pure carbon films exhibited a hardness of ~13 GPa, which is only slightly increased up to ~14 GPa by the doping. No significant variation of hardness with dopant type (V, Zr), dopant concentration and annealing temperature (<1300K) was observed. |
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