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 × 10¹⁴÷3 × 10¹⁵ cm² 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. (paper)