Effect of residual stress on the Raman-spectrum analysis of tetrahedral amorphous carbon films

Tetrahedral amorphous carbon (ta-C) films deposited by the filtered vacuum arc process have large compressive residual growth stresses that depend on the atomic-bond structure. We observed that the G peak of the Raman spectrum shifts to higher frequency by 4.1±0.5 cm−1/GPa due to the residual compressive stress. This value agrees well with the calculated Raman-peak shift of the graphite plane due to applied stress. By considering the effect of residual stress on the G-peak position, we also observe a similar dependence between the G-peak position and the atomic-bond structure in both ta-C and hydrogenated amorphous carbon (a-C:H) films; namely, that a higher sp2 bond content shifts the G-peak position to higher frequency.