Spike effects in heavy-ion sputtering of Ag, Au and Pt thin films

Sputtering yields of Ag, Au and Pt have been measured for monatomic and polyatomic ions of P, As, Sb and Bi over the energy range 10–250 keV. Large enhancements of the measured sputtering yields over those predicted by cascade theory occur for the very heavy ion bombardments. These enhancements become much larger for polyatomic ion bombardment and are strongly non-linear with the number of atoms comprising the molecule. The high sputtering yields are consistent with a major contribution due to a highly disrupted surface region and an associated reduction in the surface binding energy. They cannot be explained using a thermal spike model in which the enhancement results from a localized evaporation.