Relationship between bonding structure and mechanical properties of amorphous carbon containing silicon

Unhydrogenated amorphous carbon films with different silicon concentrations were synthesized by magnetron sputtering, and the corresponding evolution of inter-atomic bonding configurations, surface roughness and mechanical properties like hardness, modulus and stress was analyzed. Introducing silicon into amorphous carbon not only reduced the sp2-hybridized carbon bonding, it also helped to reduce residual stress. Both the hardness and elastic modulus suffered degradation when the silicon concentration was low. But these properties recovered when silicon dosage increased. Surface roughness increased when silicon concentration was low, but decreased when the silicon dosage increased. Such changes in the mechanical properties were closely related to the carbon and silicon inter-atomic interaction. The amorphous carbon network was modified by silicon, and affected by deposition kinetics. The mismatch in the atomic size and bond length, and the alteration of the carbon hybridization were determined to be the basis for the changes in the mechanical properties.