Carbon diffusion in alumina from carbon and Ti2AlC thin films

Carbon diffusion is observed in single crystal α-Al2 O3 substrates from carbon and Ti2AlC thin films synthesized via pulsed cathodic arc deposition. Diffusion was found to occur at substrate temperatures of 570 °C and above. The diffusion coefficient of carbon in α-Al2 O3 is estimated to be of the order 3×10-13 cm2/s for deposition temperatures in the 570–770∘C range by examining elastic recoil detection analysis (ERDA) elemental depth profiles. It is suggested that an appropriate diffusion barrier may be useful when depositing carbon containing thin films on α-Al2 O3 substrates at high temperatures.