Published online by Cambridge University Press: 10 February 2011
In order to interpret the projection range and to reveal the mechanism of damage formation by cluster ion impact, molecular dynamics simulations of a fullerene carbon cluster (C60) impacting on diamond (001) surfaces were performed. When the kinetic energy of C60 is as low as 200eV/atom, C60 implants into the substrate deeper than a monomer ion with the same energy per atom because of the clearing-way effect. The kinetic energy of the cluster disperses isotropically because of the multiple-collision effect, and then a large hemispherical damage region is formed. When the energy of the cluster is as high as 2keV/atom, the cluster dissociates in the substrate, and then cascade damage is formed like in a case of a monomer ion impact. The projection range of incident atoms becomes similar to that of the monomer with the same energy per atom. However, the number of displacements of C60 is larger than the summation of 60 monomer carbons. The displacement yield of fullerene is 4 to 7 times higher than that of monomer carbon. This result agrees with the measurement of the displacements made on sapphire substrates with C60 and C2 irradiation.