Thermal stability and nano-structure of metal-doped carbon layers

Carbon layers doped with Ti, V, W, and Zr to about 15 at.% were produced by means of magnetron sputter deposition, which distributes metal atoms homogeneously in the amorphous carbon matrix. The effects of thermal annealing to temperatures of 500–1300 K on the phase, crystallinity and distribution of the dopant were determined. X-ray diffraction (XRD), MeV ion beam analysis (IBA), and extended X-ray absorption fine-structure spectroscopy (EXAFS) were used for characterization. The three techniques deliver complementary information on different length scales of the diffusion and crystallization. All four metal dopants are in carbidic state with crystallites on the nanometer scale after annealing to 1100 K. Dopant diffusion of no more than 20 nm, even after heating at 1300 K for 2 h, was observed.