Effect of ion bombardment on the phase composition and mechanical properties of diamond-like carbon films

Abstract

It is established that the addition of hydrogen to methane in the reaction mixture upon the fabrication of diamond-like carbon films via the plasma-enhanced chemical vapor deposition method decreases residual stresses in the obtained films and significantly reduces their growth rate. The films were investigated via atomic force microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. Irradiation of the prepared films with P+ and PF 4 + ions results in strong sample swelling with increasing dose, as well as in a decrease in the compressive stress up to transition to tensile one reaching saturation. Moreover, the fraction of sp 3 bonds increases with increasing ion dose while the fraction of sp 2 bonds decreases symmetrically with the processes proceeding faster upon irradiation with molecular ions. Qualitative mechanisms explaining the experimental results are proposed.