Transmission sputtering of gold by heavy ions in the lower keV energy region

Abstract

Transmission and back-sputtering yields have been measured from epitaxially grown (100) and (111) gold single crystals of 40 A to 400 A thickness, bombarded with Ar⁺, Kr⁺ and Xe⁺ ions in the energy range 250 eV to 8 keV and at target temperatures between 80 K and 400 K. Combined Electron Microscopy and Microprobe Analysis (EMMA) was used to analyse the sputtered material, which was collected on thin carbon fdms substrates, as well as the gold fdms before and after bombardment. Substantial transmission sputtering is found far beyond the predicted range of the random collision cascade. transmission sputtering yields are shown to be consistent with a model assuming channelled ions to be responsible for sputtering beyond the random range, rather than long range focussed collision sequences. The experiment sets an upper limit of about 50 A (or about 17 collision steps) for the range of a (110) focussed collision sequence in gold, which contribute to transmission sputtering in the temperature range investigated.