Elements added diamond-like carbon films (hydrogen, fluorine,
and sulfur) were prepared on Si (100) wafers by the PBII technique.
The films were investigated in term of their structures, mechanical
properties, and tribological properties by using Raman spectroscopy,
nano-indentation hardness testing, contact angle measurement, and
ball-on-disk friction testing. It was observed that by increasing the C:H,
C:F, and C:S flow rate ratio, the hydrogen, fluorine, and sulfur contents
in the films decreases while the hardness and the elastic modulus
increases. The hardness and elastic modulus of H-DLC films can
increase values up to 11.2 GPa and 107 GPa with a C:H flowrate ratio of
2:1. Furthermore, the contact angle of all films tends to increase, while
the total surface energy gradually decreases with the hydrogen,
fluorine, and sulfur incorporation. H-DLC films at C:H flow rate ratio of
1:4 under ambient air shows a friction coefficient of 0.08, which is
considerable improvement in the tribological properties. This is due to
the formation of transfer films on the interface and high hydrogen
contents. The H-DLC films show lower friction coefficients and shorter
friction endurance under high vacuum than the S-DLC films, which is
because high hydrogen contents and C–H bonds are broken more
easily than C–S bonds. F-DLC and DLC-SP films show the friction
endurance was failed easily during tests due to low hydrogen contents.
The decrease in the friction coefficient is greater under high vacuum
than under ambient air.