Structure and Properties of Si Incorporated Tetrahedral Amorphous Carbon Films Prepared by Hybrid Filtered Vacuum Arc Process

Churl Seung Lee, Kwang-Ryeol Lee, Kwang Yong Eun, Ki Hyun Yoon and Jun Hee Han 

Mechanical properties and atomic bond structure of Si incorporated tetrahedral amorphous carbon (ta-C)  film were investigated. The  flms were deposited by filtered vacuum arc of graphite with simultaneous sputtering of Si. Si concentration in the film could be controlled by changing the flow rate of the Ar sputtering gas. It was observed that the incorporated Si preferentially substituted the carbon of sp³ bond when the Si concentration was less than 2.5 at.%. Since the Si-C bond generated by the substitution is weaker than C-C bond, the Si incorporation could cause the relaxation of nearby distorted C-C bonds by inducing large strain in the Si-C bond. This structural change resulted in a signi cant decrease in the residual compressive stress in this Si concentration range. In contrast, the incorporated Si which has only sp³ hybridization, generated the weaker Si-C bonds without breaking the three dimensional interlinks of the atomic bond structure. Hence, the hardness and the planes strain modulus gradually decreased with the Si incorporation. Saturated mechanical properties observed when the Si concentration was higher than about 10 at.% are due to the formation of large amount of SiC phase in the deposited film.