Simulation of Silicon Irradiation with C60 Ions: Unveiling the Role of the Interaction Potential

Abstract

Molecular dynamic simulation was used to study the processes of molecular 2 to 14 keV C60 ion impact on the (100) Si surface at 0 to 1000 K. Tersoff-ZBL and Airebo interaction potentials were used, and electronic energy loss were taken into account as quasifriction force for fast particles. It is shown that, when single impact events are simulated, the target temperature does not affect the development of the displacement cascade but affects its thermalization and the formation of the crater on the surface. As the energy increases, the carbon penetration depth, the size of the formed crater, and the size of the rim increase. The sputtering coefficient of silicon atoms in this case increases linearly with energy, while for carbon atoms it reaches a steady-state value at 10 keV. A higher number of atomized carbon atoms in single impact events is found using the Tersoff potential compared to the Airebo potential. In the event of cumulative events, the formation of an etch pit is observed at the initial stage followed by carbon film growth. In the case of cumulative ion accumulation, the use of the Airebo potential yields a higher sputtering coefficient than the use of the Tersoff potential. The formation of carbide bonds in the crystal and the increase in their concentration with ion fluence slightly reduce the number of sputtered particles. Therefore, for the correct comparison of simulation results with experiment it is not enough to use the results of single impact event analysis. It is necessary to perform cumulative fluence accumulation simulation.