Surface composition changes in Au-Cu alloys: interplay of mass-related preferential sputtering and bombardment-induced segregation

Abstract

The surface composition changes caused by heating and ion sputtering were studied in five Au–Cu alloys using the AES calibration curve method. A new phenomenon was found in ion-sputtered alloys: component enrichment at the near-surface region (beneath the topmost layer) is strongly related to the bulk composition. For copper-riched alloys, gold will be enriched at the near-surface region; for gold-riched alloys, copper will be enriched at the near-surface region. This phenomenon does not occur in heated alloys, so the factors governing thermo-activated segregation are excluded. Concerning the factors relating to ion sputtering, we suggest a combination of bombardment-induced Gibbsian segregation (BIGS) and mass-related preferential sputtering, both of which are related to bulk composition. Copyright © 1999 John Wiley & Sons, Ltd.