The effects of dopants on the chemistry and tribology of sputter-deposited MoS2 films

The fact that dopants improve the friction and wear properties of sputtered MoS 2 films is well known. However, the role of dopants in the mechanisms governing friction and wear are not well understood. The purpose of this work is to gain a fundamental understanding of their role by co-depositing a number of materials, i.e., Ni, Fe, Au, and Sb 2 O 3 , with MoS 2 and evaluating their effects on film chemistry, crystallinity, microstructure, and tribology. Friction and wear measurements were collected using ball-on-flat and dual-rub shoe tribometers. Other physical and chemical properties were obtained using SEM, XPS, XRD and Raman spectroscopy. Crystalline MoS 2 was seen in all of the films. In Sb 2 O 3 -doped films, an amorphous phase was also observed. The presence of dopants caused film densification and affected crystallite size. They had little effect on the overall crystallite orientation. In addition, dopants caused a reduction in the mean and variance of the friction coefficient and an increase in wear life. The correlation between dopants, film properties, and tribology is discussed in detail.