Microstructural and surface properties of cobalt containing amorphous carbon thin film deposited by a filtered cathodic vacuum arc

Abstract

Cobalt containing tetrahedral amorphous carbon (ta-C:Co) films were deposited on silicon wafers at room temperature under various bias conditions by an off-plane double bend filtered cathodic vacuum arc technique. The microstructural and surface properties of the ta-C:Co films were systematically studied by XPS, Raman, and surface energy measurements via contact angle measurements. Incorporation of Co increases the contact angle sharply to 107.5° as compared to the value for pure ta-C of ∼80°. XPS measurements showed that an increase in negative substrate bias affects both the ${\mathrm{sp}}^3$ content as well as the Co oxidation state on the sample surface. Correlation between XPS and surface energy measurements showed that two different mechanisms might cause the overall decrease in surface free energy of the films.