Electronic Sputtering with Swift Heavy Ions

Abstract

Swift heavy ions of energies where electronic processes dominate the slowing down process in matter induce sputtering mainly by inelastic effects, and not by elastic collision cascades. Given by the high energy input per incident ion, the measurements of sputtering yields include specific problems and require different techniques than for nuclear sputtering. Electronic sputtering shows a strong dependence on material properties, therefore experimental results are presented for metals, oxides, and ionic crystals separately. The sputtering yields vary by more than four orders of magnitude and the shape of the angular distribution can be almost isotropic or exhibit a jet-like contribution. In a general accepted picture for damage creation induced by swift heavy ions, the projectiles create hot zones of molten or even vaporized material resulting in the ejection of surface atoms. The inelastic thermal spike model based on this picture reproduces quantitatively the measured sputtering yields in oxides, and indicates a synergetic effect between nuclear and electronic energy loss for metals and a non-thermal mechanism for ionic crystals.