Sputtering from Binary Alloys - A Technique for Evaluating Change in Surface Binding Energy
In recent years computer simulations, experimental observations and analyses of the collected sputtered products from the interaction of ion beams on solid materials have demonstrated the sensitivity of the sputtering process to the surface characteristics of the material being investigated or modified. The usual characterization of the target material has been a post bombardment analysis of the surface for the relative concentration of the implanted atoms compared with the initial target components coupled with an examination of the profile of the implanted atoms in the surface region. Recent experiments have collected sputtered products during ion implantation and have compared the distribution of sputtered particles with theory. Techniques have been developed to measure the partial and net sputtering yields from the amount of material collected on the foils in these experiments. Typically the evaluation of the target material and the collected sputtered products has been reported for the steady state conditions during ion implantation. Our experimental group has chosen to evaluate the sputtering process from the onset of ion bombardment through the steady state condition. From these experiments models have been proposed for the behavior of the surface composition and the sputtering yields. Techniques developed for monitoring of the surface have provided data supporting the concept that the average surface binding energy of the bombarded target material is sensitive to the sputtering process. Calculating the manner in which the surface binding energy will change with the developing atomic surface fraction can qualitatively lead to more precise prediction of implantation requirements.