Variation of the sputtering yield of gold with ion dose

Abstract

In an earlier publication¹ it was noted that the sputtering yields of gold varied considerably over an initial bombardment period during which approximately 6 × 10¹⁶ ions/cm² struck the target surface; above this dose yields became constant and agreed reasonably well with other sources of data. The present work describes a modified version of the original apparatus which allows up to one hundred experiments to be carried out in one evacuation under better U.H.V. conditions than previously attained. 0–600 eV Nitrogen (N₂) ions have been used and, as the present technique allows measurement of total yields as low as 10¹² atoms, a careful study of the sputtering yield-dose pattern has been possible. Scanning electron micrographs of the gold surface at various stages of the bombardment indicate only slight surface roughening. A model is proposed based on the development of dislocation loops which could explain the relatively long recovery time in the 600 eV yield which follows a short bombardment at a lower energy.