Sputtering due to Coulomb explosion in highly charged ion bombardment

Sputtering processes of silicon in the bombardment of highly charged ions (HCIs) are studied using molecular dynamics simulation. Assuming the potential energy of the HCI transferred to target is stored as the electrostatic energy of Si atoms ionized by the HCI, the Si ions up to 375 are embedded on a Si(100) surface as an initial condition, resulting in Coulomb explosion. The dynamics of particle ejection (sputtering) from the surface and crater formation on the surface are simulated. The formation and propagation of shock wave and rapid increase of the sputtering yield are seen during relaxation process. Strong dependence of the sputtering yield on the HCIs potential energy is found and discussed in comparison with experiment.