Published online by Cambridge University Press: 28 January 2016
Single- and multi-layer amorphous carbon (a-C) films of varying thickness were deposited on Si(100) substrates by radio-frequency sputtering in a pure Ar atmosphere. The thickness, roughness, coefficient of friction, and residual stress of the a-C films were measured by profilometry, atomic force microscopy, surface force microscopy, and curvature method, respectively. The through-thickness nanostructure and elemental composition of the films were examined by cross-sectional transmission electron microscopy and electron energy loss spectroscopy. The multi-layer a-C films, consisting of alternating ∼10-nm-thick hard and soft a-C layers deposited under 0 and −200 V substrate bias, respectively, were found to exhibit lower roughness, coefficient of friction, and residual stress and slightly higher tetrahedral carbon atom hybridization than single-layer a-C films of similar thickness. The results of this study reveal a strong correlation of the friction characteristics with the surface roughness and nanostructure of single- and multi-layer a-C films.