Highly resolved analysis of the chemistry and mechanical properties of an a-C:H coating system by nanoindentation and auger electron spectroscopy

The small-angle cross-section method was applied to a multi-layered hydrogenated amorphous carbon coating (a-C:H) system deposited by plasma enhanced chemical vapour deposition. The investigated system consists of a silicon rich adhesion layer and an adjacent ramp layer with a graded chemical composition to the a-C:H coating. The mechanical properties and the corresponding chemical gradients of the coating system were analysed by a combination of the small-angle cross-section method together with auger electron spectroscopy and nanoindentation. Furthermore, energy filtered transmission electron microscopy on a thin lamella was used to check the reliability of the auger electron spectroscopy results. It was found that local gradients in the chemical composition within the coating relate well to gradients observed in the local mechanical properties. The used combination of the different methods enables to resolve the correlation between the microstructure, chemical composition and mechanical properties of thin film systems with high spatial resolution.