EFFECT OF MOLYBDENUM CONTENT ON THE STRUCTURE AND TRIBOLOGICAL PROPERTIES OF DIAMOND-LIKE CARBON FILMS

Abstract

: Molybdenum doped amorphous diamond-like carbon thin films (Mo-DLC) were deposited on Si (100) substrates by magnetron sputtering. The graphite and the molybdenum cathode current were fixed at 1 A and 0.25 A, respectively. The deposition duration was 600 s, and the distance was 6 cm. During the deposition the Mo content was changed by increasing the opening of a shield mounted above the Mo target from 4 mm to 32 mm and at the end without shield. The elemental composition, surface morphology, structure, and friction forces of the films were investigated by energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (multimode 8 Bruker) and Raman spectroscopy. The EDS results indicated that the Mo content increased with the opening of the shield above the Mo target. Additionally, the Raman spectra of the films indicated that the sp² carbon sites fraction increased, and graphitization was induced. The average surface roughness R_a slightly increased from 1.3 to 2.7 nm with the rise of Mo content. The friction coefficient of the Mo doped DLC films depended on the structure and composition of the films.