Post-field ionization of Si clusters in atom probe tomography: A joint theoretical and experimental study

A major challenge for atom probe tomography (APT) quantification is the inability to decouple ions that possess same mass–charge (m/n) ratio but a different mass. For example, 75As+ and 75As22+ at ∼75 Da or 14N+ 28Si2+ ∼14 cannot be differentiated without additional knowledge of their kinetic energy significant improvement mass resolving power. Such peak overlaps lead ambiguities in assignment, resulting compositional uncertainty an incorrect labeling atoms reconstructed volume. In absence practical technology measuring field-evaporated ions, we propose then explore applicability post-experimental analytical approach resolve this problem based on fundamental process governs production multiply charged molecular ions/clusters APT, i.e., post-field ionization (PFI). The ability predict PFI behavior as function operating conditions could offer first step toward overlap minimizing uncertainty. We possibility by comparing field dependence charge-state-ratio Si clusters (Si2, Si3, Si4) with theoretical predictions using widely accepted Kingham theory. discuss model parameters may affect quality fit possible ways which APT can better understood. Finally, test transferability proposed material systems outline forward achieving more reliable results.