Structural modification of Ga+ and N+ ion implanted ta-C films

Thin-film samples (d ~ 40 nm) of tetrahedral amorphous carbon (ta-C) deposited by filtered cathodic vacuum arc (FCVA) were implanted with Ga+ at ion energy E = 20 keV and ion fluences D = 3×10^14÷3×10^15 cm-2 and N+ with the same energy and a dose D = 3×1014 cm-2. The Ga+ ion beam induced a structural modification of the implanted material. This resulted in a considerable change of its structural properties, manifested as the formation of a new phase under non-equilibrium conditions, which could be accompanied by considerable changes in the ta-C films optical properties. The N+ implantation also resulted in a modification of the surface structure. These effects were explored using transmission (TEM) and scanning (SEM) electron microscopy.