Stress reduction dependent on incident angles of carbon ions in ultrathin tetrahedral amorphous carbon films

摘要

We presented the combined experimental and simulation study on stress evolution as a function of incident angles of carbon ions for the ultrathin tetrahedral amorphous carbon films (ta-C). The residual stress was found about 3.6 ±0.1 GPa for the incident angle of C ions with range of 0°-30°, while it decreased significantly to 2.8 GPa with the incident angle of 60°. Different with the previous reports, noted that in this case both the sp~3 content and mechanical properties of film were not deteriorated. Taking molecular dynamics simulation, it was in particularly concluded that the critical relaxation of distorted C-sp~3 bond lengths and bond angles played key role on the unusual stress reduction mechanism. The results provide a route to fabricate the ultrathin ta-C films with low stress and high hardness for the precision wear resistant applications.