Computer simulation of sputtering of Cu(111) and Ni(111) surfaces under the action of accelerated beams of ions and clusters

The self-sputtering of Cu(111) and Ni(111) surfaces under bombardment with CuN and NiN (1 ≤ N ≤ 55) atomic ions multiatomic clusters with energy per one incident atom (E/N = 500 eV/atom) is investigated by means of classical molecular dynamics method. As a result of performed simulation, a number of pronounced non-linear effects in sputtering (such as a non-additive increase of sputtering yield, late emission, change of energy-angular spectra of secondary emission) are observed in case of bombardment with clusters of more than 10 atoms. These effects take place due to formation of a dense collisional cascade and a post-cascade heat spike in the irradiated material. In the framework of the study the influence of electron deceleration and electron-phonon coupling on features of collisional cascade development and secondary emission is discussed/ It is shown that in spite of nearby atomic numbers of Cu and Ni, the influence of interaction between atoms and electronic subsystem of the target on secondary emission is more pronounced for Ni