Sputtering of the alloy systems AgAu, AuCu, and AgCu studied by Auger electron spectroscopy

Abstract

In the present work, preferential sputtering has been studied for the binary systems AgAu, AuCu, and AgCu. Several alloys of each system with given bulk compositions have been sputtered by 1 keV argon ions while the surface composition was analyzed by Auger electron spectroscopy. AgAu and AuCu are one-phase systems with a continuous series of solid solutions over the whole concentration range, whereas AgCu is a two-phase system with an eutectic point at 39.9 at% Cu. In the system AgAu sputtering yields an enrichment of Au caused by preferential sputtering of Ag. It is shown that the enrichment is larger in the topmost surface layer and decreases with increasing depth. The enrichment of Au is in qualitative agreement with the sputter coefficients of the pure elements. By sputtering AuCU alloys no enrichment of a component is detected in accordance with a ratio of one for the sputter coefficients of pure Au and pure Cu. The ratio of the sputter coefficients for the systems AgAu and AuCu was found to be essentially constant over the whole concentration range. All sputtered AgCu alloys show an enrichment in Cu.