Secondary ion mass spectrometry (SIMS) has been utilized to study compositional gradients in compound-sputtered and annealed Cu2ZnSn(S,Se)4 (CZTSSe). SIMS image depth profiling shows a non-uniform spatial distribution of selenium and supports a mechanism where selenization is accompanied by grain growth rather than substitution of selenium for sulfur. Furthermore, SIMS depth profiles of S and Se using O2+ primary ions and detecting molecular ions of the MCs+ type using Cs+ primary ions have been compared, where a linear relationship between the sulfur and selenium concentration suitable for compositional analysis is observed for concentrations with an Se/(S+Se) ratio in the range from 0.25 to 0.65. 

[3D image of the spatial Se distribution in a 20 × 20 μm2 grid measured with SIMS image depth profiling.]