Hardness and stress of amorphous carbon films deposited by glow discharge and ion beam assisting deposition

The hardness and stress of amorphous carbon films prepared by glow discharg e and by ion beam assisting deposition are investigated. Relatively hard an d almost stress free amorphous carbon films were deposited by the glow disc harge technique. On the other hand, by using the ion beam assisting deposit ion, hard films were also obtained with a stress of the same order of those found in tetrahedral amorphous carbon films. A structural analysis indicat es that all films are composed of a sp(2)-rich network. These results contr adict the currently accepted concept that both stress and hardness are only related to the concentration Of sp(3) sites. Furthermore, the same results also indicate that the sp(2) sites may also contribute to the hardness of the films.