How non-destructive is ISS?

Abstract

Ion scattering spectroscopy (ISS) is normally considered a non-destructive technique for surface analysis, while secondary ion mass spectrometry (SIMS) is intrinsically destructive. However, both SIMS and ISS use similar primary beams in the kilo-electron-volt region to perform surface analysis. Although energies and projectile mass are chosen in order to minimize or maximize sputtering for each technique, care should be taken when ISS is performed. Indeed, while sputtering is essential for SIMS, it is unwelcome in ISS. In this paper, we discuss how sputtering may become possible by light ions in the energy range of some 100 eV to some keV. We describe the mechanisms and threshold energies, what is preferential sputtering and how large the absolute value of the sputtering yields should be. We also give details about the emission anisotropy of the sputtered particles for single crystals. Finally, we suggest a way to evaluate the erosion rate under typical ISS conditions and we present examples of He + and Ar + on a Ba target.