Nanocharacterization Using Secondary Ion Mass Spectrometry (SIMS)

Secondary Ion Mass Spectrometry (SIMS) using ultralow energy beams (<1keV) gives the capability to measure structures within films as thin as 1nm. By measuring SiO2 calibration films of known thickness and extrapolating back to zero thickness, we can calculate the ion mixing depth of the SIMS measurements. These data show that SIMS can achieve depth resolution of less than 1nm using beams of 700-300eV. By using an inorganic elemental tag, an isotopic tag or staining, low energy depth profiling can also discern the structure of planar organic films. We give examples of Zn-doped layers of tetraphenylporphyrin (TPP) and a self-ordered polystyrene/polybutadiene copolymer film stained using OsO4. Standard SIMS measurements have also been carried out on doped Si nanowires to measure boron doping levels.