Large electronically mediated sputtering in gold films

Electronically mediated sputtering in thin gold films, bombarded with 200-MeV Ag ions, has been observed by ex-situ thickness measurements of the film using x-ray reflectivity technique. The observed sputter yield depends upon the film thickness and is about 410 atoms per incident ion for films of thickness 150 Angstrom and 235 atoms per incident ion in 450-Angstrom -thick film. This sputtering rate is a few orders of magnitude higher as compared to that normally encountered in the regime of elastic collisions. Reduced mobility of the electrons due to scattering from the surface and the grain boundaries plays an important role in enhancing the effects of electronic excitations. Sputtering is accompanied by a significant smoothening of the film surface and smearing of the boundaries between the grains.