Nanocrystals depth profiling by means of Cs+ in negative polarity with dual beam ToF-SIMS

We developed an empirical method to perform quantitative depth profiles of antimony nanocrystals embedded in silicon oxide with a dual beam ToF-SIMS using Cs+ in negative polarity. We assumed that the Cs concentration in the oxide layer is constant and the variation in signal intensities are due essentially to matrix effects related to changes in the oxidation state of antimony. A parameter that describes the oxidation state of the species of interest was established on the basis of the relative intensity of different antimony containing clusters. We developed a quantitative relationship between this parameter and the ionization probability. In this way it was possible to correct the Sb signal obtaining a matrix independent signal that give us the possibility to realize a quantitative depth profile.