Sputtering of Au (1 1 1) by 64 keV/atom Au clusters

Abstract

Using molecular-dynamics simulation, we study the sputtering of a Au (111) surface due to impact of Aun clusters (n=1,2,4,8,13) with an energy of 64keV/atom. We measure the initial sputter yield Yinit at the time when the maximum number of atoms energized to above the cohesive energy of the material has been generated; this time is roughly 0.5ps after projectile impact. Yinit is proportional to the energy deposited near the surface, FD. We correlate FD to the final sputter yield Yfinal, measured at roughly 100ps after projectile impact. The good correlation between the deposited energy and the final sputter yield proves that sputter yield fluctuations mainly originate from the early phase of energy deposition. An overview over the available sputter yield simulations of Au cluster impact into Au shows a rough proportionality of the final yield to the total cluster energy. Deviations occur for small clusters and are believed to be due to range straggling, which induces a variation of the deposited energy at the surface.