Q-carbon, an allotrope of carbon, exhibits exciting functional properties and robust mechanical strength. We propose that the surface of the Q-carbon can be functionalized by doping it with silicon to enhance its performance as a potential implant material. As such, a coating of silicon-doped Q-carbon (Si-Q-carbon) is shown to minimize the formation of biofilm, thus reducing the risk of microbial infection. We report the formation of Si-Q-carbon coatings of varied thicknesses (10nm and 20nm) through the plasma-enhanced chemical vapor deposition technique. The surface composition and the bonding characteristics of the thin films were evaluated by Raman spectroscopy, XPS, and EELS studies, which showed that the thinnest sample (10nm) has a high sp3 content of ∼85%. Furthermore, wettability and surface energy calculations were undertaken to investigate the surface characteristics of the coatings. The 10nm sample was found to be more hydrophilic with a water contact angle of 75.3° (± 0.6°). The antibacterial activity of Si-Q-carbon coatings was investigated using a Staphylococcus epidermidis agar plating technique, and the adhesion of bacteria was explained in terms of the surface properties of the thin films. We demonstrate that the Si-Q-carbon coating with the highest sp3 content is hydrophilic and showed a 57% reduction in adhered biofilm relative to a glass control. We envisage the potential application of Q-carbon in arthroplasty devices with enhanced mechanical strength and resistance to periprosthetic joint infections.