Preparation and antibacterial properties of Ag-containing diamond-like carbon films prepared by a combination of magnetron sputtering and plasma source ion implantation

Ag-containing diamond-like carbon (DLC) films were prepared on austenitic type stainless steel SUS316L and silicon wafer substrates by a process combining reactive magnetron sputtering with plasma source ion implantation (PSII). An Ag disc was used as a target for the sputter source with an RF power of 100 W. A mixture of the gases Ar and C2H2 was introduced into the discharge chamber while a negative high voltage pulse was applied to the substrate holder. By changing the gas flow ratios the resulting Ag content of the films could be varied. The prepared films were composed of amorphous carbon with crystalline Ag, as observed by X-ray diffractometry and TEM. Additional sample characterizations were performed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry and Raman spectroscopy. The surface morphology was observed by scanning electron microscopy. The antibacterial activity was determined using Staphylococcus aureus bacteria. All Ag-containing diamond-like carbon films exhibited an antibacterial activity with only small variations depending on the Ag content.