A sustainable deposition method for diamond-like nanocomposite coatings – Insights into the evolution of atomic structure and properties

Abstract

Silicon and oxygen-doped hydrogenated amorphous carbon (a-C:H:Si:O), typically termed as diamond-like nanocomposite (DLN), is amongst the most widely adapted coating materials for advanced applications. Traditionally, these coatings are deposited by plasma-enhanced chemical vapor deposition (PECVD) using organosilicon precursors, which not only restrict coating stoichiometry but also have a high environmental footprint. Here, we report the deposition of highly dense and microscopically defect-free a-C:H:Si:O coating using magnetron sputtering as a facile and sustainable deposition method that allows a fine stoichiometry control. Furthermore, we investigate the evolution of the atomic structure and the local-atomic environment when Si, O, and H atoms are successively doped into the amorphous carbon (a-C) matrix. Diffraction and spectroscopic analyses of doped coatings indicate the absence of any long-range order and an atomic-scale composite structure. The results also establish that doping of a-C leads to improved sp3 bonding, formation of Si–O-based networks, and termination of carbon dangling bonds, resulting in increased structural stability. The densification of the coating, combined with improved sp3 character, results in hardness and modulus exceeding those of PECVD-deposited coatings. These findings present a viable potential of magnetron sputtering as a straightforward and greener alternative to traditional PECVD-based methods for producing a promising coating material.