Enhanced sputtering yield of nanostructured samples under Ar⁺ cluster bombardment

Ar₂₉₀₀ clusters with energy in the range of 10.4–69 keV were used to bombard the surface of pressed Si nanopowder targets. High nonmonotonic sputtering yield is observed within the energy range of 10.4–34.5 keV, which is considered as enhanced by the finite size effect of the target particles. The cluster bombardment results in the sputtering of Si nanoparticles with a mean size of ca. 12 nm. The number of the sputtered nanoparticles is correlated with the sputtering yield within the energy range of 10.4–34.5 keV. Hence, their formation is associated with the finite size effect. Scanning electron microscopy revealed the formation of debris on the target surface starting at the cluster energy of 15.3 keV, which results in reducing the finite size effect and consequently the sputtering yield. Individual impacts of the argon clusters are observed as craters of 3–6 nm in diameter on the Si particles surface. The crater formation is considered to be responsible for the sputtering at the cluster energy in the range of 15.3–69 keV.