Carrier gas and ion beam parameter effects on the structure and properties of a-C:H/SiOx films deposited employing closed drift ion beam source

In the present study closed drift ion beam source was used to deposit SiOx containing amorphous hydrogenated carbon films (a-C:H/SiOx) employing hexamethyldisiloxane and H2 or He carrier gas. The structure, optical and mechanical properties of a-C:H/SiOx films deposited using different ion beam energies (300-800 eV) and ion beam current densities (20-80 μA/cm2) were analyzed. Raman spectroscopy has shown that the structure of a-C:H/SiOx films deposited using different carrier gas differs. In the case of H2 carrier gas I(D)/I(G) ratio decreased from 1.1 to 1 with the increase of ion beam energy from 300 eV to 500 eV. It is shown that the increase tendency observed for I(D)/I(G) ratio dependence on the ion beam current density was influenced by the structural changes (Si-H bonds formation) observed in FTIR analysis. The films with maximum hardness (12.8 GPa for He and 11.9 GPa for H2 carrier gas) were formed at 500 eV ion beam energy for both carrier gas. The band gap and B parameter of the films (formed at 500 eV with H2 carrier gas) increase almost linearly with the ion beam current density.