Studies of surface composition of Ag-Au, Au-Cu, and Ag-Cu alloys after ion bombardment by Auger electron spectroscopy

Abstract

Changes in the surface composition of the single-phase binary alloy systems Ag-Au and Au-Cu and the two-phase system Ag-Cu after sputtering with 1-keV Ar+ ions have been studied by Auger electron spectroscopy. A different behavior was observed for single-phase and two-phase systems. For the single-phase systems no change in surface composition can be detected after stopping sputtering. Therefore, the results in surface composition agree with those obtained during sputtering. However, for the two-phase system Ag-Cu the surface becomes enriched in Ag within a few minutes after prolonged ion bombardment is stopped. Assuming surface diffusion a simple model shows that the surface becomes covered by about one to two atomic layers of Ag, independent of the Ag bulk concentration. Furthermore, experiments with a 40 at.% Ag-60 at.% Cu sample indirectly heated to 350 °C indicate that surface diffusion is enhanced by radiation damage produced by ion bombardment.