Simulation of the sputtering of Si nanoclusters with diameters of (2–8) nm under bombardment with monatomic and cluster ions using the method of classical molecular dynamics

Abstract

The sputtering of Si nanoclusters with diameters of (2–8) nm under bombardment with Si1 ions and Si12 clusters with energies of 1 to 12 keV has been studied using the method of classical molecular dynamics. It is shown that the total sputtering yield is higher under the bombardment of nanoclusters with monatomic ions than in the case of the crystal plane surface mainly due to an increase in the contribution of the cluster component of the secondary-emission spectrum. In this case, in practice there is nonoccurrence of any correlation between the secondary-emission characteristics and the particle-projectile impact parameter. In the case of cluster bombardment, the cluster component of the spectrum of sputtered particles is dominant for large impact parameters (i.e., for glancing impact) and the sputtering yield and the probability of the ejection of large fragments (containing half of the initial-nanocluster atoms or more) increase significantly (as compared with similar values obtained under bombardment with monatomic particles). It is established that the main mechanism for the emission of large fragments is the co-called “recoil effect”, where the impinging particle-projectile causes the secondary emission of nanocluster-target atoms predominantly toward the substrate; as a result, the cluster-target acquires momentum in the opposite direction. It is shown that this “recoil effect” can lead to the desorption of the nanocluster, deposited onto a plane Si(111) substrate.