Effects of the surface structure and cluster bombardment on the self-sputtering of molybdenum

The understanding of different features of the sputtering of materials lies in understanding the factors contributing to the emission of atoms from a regular crystal structure at the surface. Although the sputtering of fcc crystals has received much attention, the database on bcc materials is still scarce. We use molecular dynamics simulations to study the self-sputtering of the (100), (110), (111) and (112) surfaces of molybdenum. Single atoms as well as Mo2 and Mo4 clusters are used as the irradiation projectiles, in the cluster energy range of 0.125–4 keV. Contrary to the usual assumption, enhanced (nonlinear) sputtering yields are observed for the cluster bombardments at both ends of the energy range studied. The enhancements can be explained with lower threshold energies for sputtering at low energies and with a decreased fraction of channelled projectile atoms in the kiloelectronvolt energy range.