Reactive sputtering of CSx thin solid films using CS2 as precursor

Abstract

We deposit CSx thin solid films by reactive direct current magnetron sputtering of a C target in an argon plasma, using carbon disulfide (CS2) as a precursor to film growth. We investigate the influence of the partial pressure of the CS2 vapor introduced into the plasma on the composition, the chemical bonding structure, the structural, and the mechanical properties as determined by x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and nanoindentation for films deposited at 150 and 300 °C. The Raman and the XPS results indicate that S atoms are incorporated in mostly sp2 bonded C network. These results agree with previous ab-initio theoretical findings obtained by modeling of the CSx compound by the Synthetic Growth Concept. The microstructure of the films as well as the results of their Raman characterization and the nanomechanical testing results all point out that with the increasing S content some sp3 bonding is admixed in the predominantly sp2 bonded CSx network, leading to typical amorphous structure with short and interlocked graphene-like planes for S contents between 2% and 8%. We conclude that CSx thin solid films deposited by using CS2 as a precursor would be CSx films deposited at low temperature of ~150 °C and with an S content in the region of 6 at.% may be interesting candidates for applications as hard/elastic protective coatings.