Ejection pattern of sputtered atoms from Cu(100) under 10 keV Ar + ion bombardment

Abstract

Sputtering of single crystalline Cu(100) has been studied in both experiment and theory. Ejection patterns of sputtered atoms from Cu(100) were observed for 10 keV Ar + ions and the result was compared with computer simulations with a modified MARLOWE code by including a disordering effect in the topmost atomic layer. In experiments, so called Wehner spots were clearly observed in the ejection patterns, suggesting that a crystalline structure remains in the surface region even though the topmost atomic layer seems to be disordered by ion bombardment. In theory the computer simulation has predicted that, when the crystalline structure of the topmost layer is disordered, the ejection pattern turns out to be almost the same as that of an amorphous target. Hence those experimental and theoretical results suggest that the atoms of the topmost layer will again occupy crystalline sites, even though the surface atoms undergo atomic mixing under 10 keV Ar + ion bombardment. A discussion on the choice of interatomic potential and the contribution of simultaneous collisions to the Wehner spot formation is also presented.