EXAFS investigation of the thermally induced structuring of titanium-doped amorphous carbon films

Amorphous carbon layers doped with 8.5 at.% titanium (a-C:Ti) were produced by dual-source magnetron sputter deposition. To investigate the local atomic environment of Ti, EXAFS analysis was performed for as-deposited layers and after annealing to 700, 1100 and 1300 K, as well as for Ti and TiC bulk samples. After deposition of the a-C:Ti films, most Ti atoms are homogeneously distributed in an amorphous carbon matrix. Annealing to 700 K slightly increases the order in the Ti environment, but TiC-like crystallization is hardly existent. After annealing to 1100 K, clear correspondence to the TiC standard is observed. Annealing to 1300 K further increases the order and TiC crystallite size. Fitting of EXAFS data to a theoretical model was used to derive quantitative parameters for a-C:Ti layers, e.g., Ti–C and Ti–Ti distances and ordering parameters.