Speaker
Description
Three-dimensional elemental mapping at nanometer-scale resolution by atom probe tomography (APT)
M. Dialameh1, J. Scheerder1, R. Morris1, and C. Fleischmann1,2
1 imec, Kapeldreef 75, 3001 Leuven, Belgium
2 KU Leuven, Department of Physics and Astronomy, Quantum Solid-State Physics, 3001 Leuven, Belgium
masoud.dialameh@imec.be
Advances in atom probe tomography (APT) have expanded its capabilities beyond conventional applications in metal alloys, enabling diverse types of analyses across a broader range of material systems, including complex semiconductors, advanced catalysts, battery and sustainable energy materials, each highly relevant to the circular economy. The developments are driven by the unique capability of APT to combine three-dimensional nanometer-scale spatial resolution with isotopically precise elemental identification of both heavy and light elements, including hydrogen [1]. These strengths enable diverse types of materials analysis, including voxel-based 3D compositional mapping with a sensitivity approaching parts-per-million level depending on the voxel volume [1]; detection and characterization of solute clusters, precipitates, and segregated regions as small as ~1 nm [2]; nearest-neighbour distribution analysis; and proximity histograms for quantitative interface characterization.
APT operates on the principle of controlled field evaporation from a needle-shaped specimen. During analysis, surface atoms are sequentially ionized, accelerated in a strong electric field, and detected by a position-sensitive detector coupled with time-of-flight mass spectrometry. Subsequent data analysis and three-dimensional reconstruction of the detected ions allow the original atomic arrangement within the specimen to be resolved, under ideal conditions. This provides atomic-scale insights from local, nanometer-sized regions of a material, in contrast to most X-ray based techniques that yield ensemble-averaged measurements. In practice, however, accurate APT analysis of complex material systems faces several challenges, including reliable specimen preparation, preferential ion evaporation in heterogeneous systems, and data reconstruction artifacts.
This presentation will provide a brief introduction to the fundamentals of APT, covering field evaporation, specimen preparation, and three-dimensional data reconstruction. A selected case studies of APT analysis on semiconductors and metal alloys will be presented, with the emphasis on potentials and the challenges of applying APT to such material systems.
References
[1] Gault, Baptiste, et al. "Atom probe tomography." Nature Reviews Methods Primers 1.1 (2021): 51.
[2] De Geuser, Frédéric, and Baptiste Gault. "Metrology of small particles and solute clusters by atom probe tomography." Acta Materialia 188 (2020): 406-415.
