Assessments of surface composition and sputtering yield of Au-Cu alloys for Ar + ion bombardment

Abstract

The possible effect of current density on the outermost surface-layer composition of Au-Cu alloys under keV Ar + ion bombardment at steady state was examined through the mixed-ion beam ISS technique. Measurements of the sputtering yields with a quartz-oscillator mubalance were performed simultaneously. Results of the former measurements indicate that the composition of the outermost atomic layer does not depend on the current density of the primary ion beam in the range from ≈0.5 to ≈90 μA/cm 2, resulting in the enrichment of Au atoms at the outermost atomic layer. The latter have lead to the same result for the total sputtering yield for ion beam intensity ranging from tens of a μA/cm 2 to several hundreds μA/cm 2. Hence both the results lead to the conclusion that the ion enhanced subsurface re-distribution process of the outermost surface atoms under Ar + ion bombardment is much faster in time than the sputter removal rate of atoms from the surface.