Effect of Cu content on microstructure, morphology, and antibacterial properties of Ti-Cu alloy thin films

Ti-Cu alloy thin films exhibit considerable potential for the development of advanced antibacterial surfaces, particularly for biomedical applications. In this research, Ti-Cu binary alloy thin films with a wide range of Cu content from 25.8 at% to 77.8 at% were deposited using magnetron co-sputtering with pure Ti and Cu as the targets. The composition of Cu in the films can be controlled by the applied power of Cu targets. This study investigated the effect of Cu content on the microstructural, morphological, and antibacterial properties using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and plate-count method, respectively. Structural analysis using XRD revealed that Ti (Cu) solid solution is formed for the Ti-Cu coatings with the Cu contents of 25.8 at% and the films tended to form an amorphous structure embedded with Cu nanocrystals when the Cu content was 77.8 at%. Surface morphology showed that the films with higher Cu content exhibited increased surface roughness and the presence of Cu nano-granular features. Antibacterial evaluations against Escherichi coli showed that the films containing Cu in the range of 25.8 at% to 77.8 at%. This effect is attributed to both inherent antibacterial properties by Cu and the microstructural modifications that enhance bacterial inhibition.