Heat treatment of tetrahedral amorphous carbon films grown by filtered cathodic vacuum-arc technique

Tetrahedral amorphous carbon (ta-C) is a potential low-cost substitute for diamond in Certain applications, but little is known of the temperature range over which its desirable properties are retained. The thermal stability of tetrahedral amorphous carbon: (ta-C) films has been investigated by heat treatment of the films at temperatures: from room temperature to 450 degrees C in high vacuum, low vacuum and oxygen ambient. It was found that heat treatment in oxygen ambient leads to a much more prominent variation in film thickness, stress and hardness than in both low and high vacuum. Raman studies, also show an increase of the G-band frequency to higher values, an increase of the integrated intensity ratio and a narrowing, of the G bands for films annealed in oxygen ambient with increasing temperature. By contrast, ta-C films exhibit a high resistance to degradation during treatment in low and high vacuum. They sustain their structure, thickness, stress and hardness for temperatures up to 400 degrees C. (C) 1999 Elsevier Science S.A. All rights reserved.