Hardness and Stress of Amorphous Carbon Films Deposited by Glow Discharge and Ion Beam Assisting Deposition

The hardness and stress of amorphous carbon lms prepared by glow discharge and by ion beam assisting deposition are investigated. Relatively hard and almost stress free amorphous carbon lms were deposited by the glow discharge technique. On the other hand, by using the ion beam assisting deposition, hard lms were also obtained with a stress of the same order of those found in tetrahedral amorphous carbon lms. A structural analysis indicates that all lms are composed of a sp-rich network. These results contradict the currently accepted concept that both stress and hardness are only related to the concentration of sp sites. Furthermore, the same results also indicate that the sp sites may also contribute to the hardness of the lms.