Effects of Ion Energy Control on Production of Nitrogen–C 60 Compounds by Ion Implantation

Nitrogen–C 60 compounds such as azafullerene (C 59 N) and nitrogen-atom-encapsulated fullerene (N@C 60 ) are produced by implanting nitrogen ions into C 60 thin films on a substrate immersed in an electron cyclotron resonance plasma under a mirror magnetic field. Each compound is found to be synthesized, depending on the ion energy provided by the potential difference between the substrate and the plasma. The optimum energy for C 59 N synthesis is approximately 40–50 eV, and the amount of C 59 N decreases in an ion energy range larger than 50 eV. In contrast, an ion energy larger than 20 eV is required for N@C 60 synthesis.