Annealing effect on the structural, mechanical and electrical properties of titanium-doped diamond-like carbon films

Titanium-doped diamond-like carbon (Ti-doped DLC) films with a Ti content of 1.1 at.% were synthesized on a Si substrate by a process that involves filtered cathodic vacuum arc (FCVA) and metal vapor vacuum arc (MeVVA) systems. The effect of annealing temperature on the microstructure, surface roughness, hardness and electrical resistivity of the resulting films was evaluated in this study. The Raman spectra revealed that the degree of graphitization of the Ti-doped DLC thin films was increased from 25 to 600 °C and the microstructure of the films is converted to a nano-crystalline graphite structure. The resulting films maintain a smooth surface after the annealing process. The hardness of the Ti-doped DLC films increases as the annealing temperature increases up to 400 °C because the induced defects and the inter-atomic bonds are repaired after the annealing process. But the hardness decreases at the higher temperature due to the increase of number and size of the nano-crystalline graphitic domains. Since the degree of graphitization of the thin films increases, the electrical resistivity of the Ti-doped DLC thin films decreases from 0.038 to 0.006 Ω cm.