Auger study of preferred sputtering on binary alloy surfaces

Auger Electron Spectroscopy has been used to investigate the preferred sputtering behavior on homogeneous Cu/Ni alloy surfaces. Measurements were made on a range of alloy compositions with Ar⁺ sputter ions of 0.5 to 2 keV energy. A kinetic model has been formulated to describe the time variation of the surface composition during sputtering. Based on this model, we were able to determine the individual sputter yields for Cu and Ni atoms in the alloy and the depth of the surface layer where the composition is altered by sputtering. The sputter yields were found to be relatively independent of the alloy composition but increased almost linearly with energy. The depth of the altered layer was comparable to the Auger sampling depth with its value increasing from 10 Å to more than 20 Å when ion energy increased from 0.5 to 2 keV.