| AVS 61st International Symposium & Exhibition | |
| Atom Probe Tomography Focus Topic | Friday Sessions |
| Session AP+AS+NS+SS-FrM |
| Session: | Correlative Surface and Interface Analysis with APT |
| Presenter: | William Lefebvre, University of Rouen, France |
| Authors: | W. Lefebvre, University of Rouen, France D. Hernandez-Maldonado, University of Rouen, France F. Cuvilly, University of Rouen, France F. Moyon, University of Rouen, France |
| Correspondent: | Click to Email |
The geometry of atom probe tomography (APT) specimens strongly differs from standard scanning transmission electron microscopy (STEM) foils. Whereas the later are rather flat and thin, APT tips display a curved surface and a significantly larger thickness. As far as a correlative approach aims at analysing the same specimen by STEM and APT, it is mandatory to explore the limits and advantages imposed by the particular geometry of APT specimens to STEM.
High angle annular dark field (HAADF) in STEM provides a contrast related to atomic number and to the amount of atoms in a column. A complete analysis of a high resolution HAADF STEM image requires the identification of projected column positions, the calculation of integrated HAADF intensity for each column and, eventually, the estimation of a “background level” generated by the amorphous carbon or oxide layer present on the specimen surface. Then, by of a statistical analysis [1], the possibility of atomic counting in an APT specimen can be explored. For this purpose, we propose an image processing method which provides a complete analysis of HAADF STEM images, that was applied here to APT specimens. In order to estimate the advantages and limitations of the method for such a particular specimen geometry, simulations have been applied and confronted to experimental results. Illustrations will be given for specimens before and after field evaporation in APT.
[1] S. Van Aert et al. Phys. Rev. B 87 (2013) 064107