SIMS is the most sensitive surface analysis technique, being able to detect elements present in the parts per billion ranges. A focused primary ion beam is sputtered on the sample surface and the secondary ions are ejected out. Such charged secondary ions are collected by the detector with a mass analyzer to determine the elemental, isotopic, or molecular composition. The dopant profile and atomic concentration can be estimated from the SIMS spectra.

Nanolab has a PHI D-SIMS 6600 system, equipped with two focused primary ion beam, O₂ and Ce, which can eject the secondary ions with positive or negative charges. There is also one electron gun to provide high energy electron beam for TV imaging and neutralization. A quadrupole mass analyzer separates the masses by resonant electric fields, where only masses of choice are able to pass and be detected by the detector. The chamber was kept in the vacuum of low 10^-10 Torr by a standard ion pump. A small load lock with a turbo pump is used to transfer the samples.

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