Structure, Optical And Mechanical Performance of Silver-Doped Diamond-Like Carbon Composite Film

The aim of this work is to study the effect of Ag concentration on the structure, mechanical and optical properties of carbon film. Knowing these values (transmission spectra, refractive index and bang gap) will allow us to develop the design of a a-C:Ag with a different Ag content. a-C:Ag films was deposited on Si and Ge substrates use the vacuum pulsed cathode arc deposition method. The concentration of silver in the a-C films was changed by using cathodes with different silver-to-carbon ratios. The concentration of elements in the coating, the chemical composition, and the structure of the resulting coatings were investigated by XPS, Raman, TEM, SEM, IR spectroscopy and laser ellipsometry. The results of TEM studies have shown that with the same thickness of the coating (about 150 nm) with increasing silver concentration, its structure changes from amorphous to the polycrystal structure. At the same time, with the increase in the silver content, the infrared transmittance of the a-C:Ag coatings gradually increases, and the area with a high transmission expands from 500 cm
_-1
to 4000 cm
_-1
. In the sample with the highest silver content, the average transmittance is above 95%. It was found that the increase in the silver content changes the interaction mechanism between carbon atoms, and increase destruction of carbonyl and hydroxyl groups, which weaken the resonance absorbance of diamond-like carbon films in the infrared light. The a-C:Ag coating has good adhesion, high hardness and a friction coefficient of about 0.3.