Study of colors of diamond-like carbon films

Reflective and transmissive film interference colors were calculated for DLC films on the Si and SiO2 substrates. The calculated interference colors were compared with photographed colors of the prepared DLC samples. The observed film colors were found to match reasonably well with the corresponding calculated colors, indicating that DLC film colors come from interference instead of color center effects. Color charts for DLC films on the Si and SiO2 substrates with various optical gaps were constructed, and the relationship between interference color and film properties such as optical gap, thickness and substrate were investigated. Usefulness of the calculated color charts in estimating optical gap or thickness of DLC films were demonstrated.