SIMS — Secondary Ion Mass Spectrometry

Secondary ion mass spectroscopy (SIMS) is an ion beam analysis technique useful for characterising the top few micrometres of samples. Primary ions of energy 0.5–20 keV, commonly O₂+, Cs+, Ar+ but also ions such as Ga+, Xe+, O-, C _{m m} + and SF₆+ are used to erode the sample surface and the secondary elemental or cluster ions formed from the target atoms by the impact are extracted from the surface by an electric field and then energy and mass analyzed. The ions are then detected by a Faraday cup or electron multiplier and the resulting secondary ion distribution displayed as a function of mass, surface location or depth into the sample (Fig. 5.1).