Atom probe trajectory mapping using experimental tip shape measurements

Abstract

SummaryAtom probe tomography is an accurate analytical and imaging technique which can reconstruct the complex structure and composition of a specimen in three dimensions. Despite providing locally high spatial resolution, atom probe tomography suffers from global distortions due to a complex projection function between the specimen and detector which is different for each experiment and can change during a single run. To aid characterization of this projection function, this work demonstrates a method for the reverse projection of ions from an arbitrary projection surface in 3D space back to an atom probe tomography specimen surface. Experimental data from transmission electron microscopy tilt tomography are combined with point cloud surface reconstruction algorithms and finite element modelling to generate a mapping back to the original tip surface in a physically and experimentally motivated manner. As a case study, aluminium tips are imaged using transmission electron microscopy before and after atom probe tomography, and the specimen profiles used as input in surface reconstruction methods. This reconstruction method is a general procedure that can be used to generate mappings between a selected surface and a known tip shape using numerical solutions to the electrostatic equation, with quantitative solutions to the projection problem readily achievable in tens of minutes on a contemporary workstation.

Quantifying Compositional Homogeneity in Pb(Zr,Ti)O3 Using Atom Probe Tomography

“…To further our understanding, finite element models are being developed to understand the complexity of the field and laser matter interactions in atom probe specimens. 62,63 Ultimately, it is known that absorption mechanisms are not only dependent on the bulk E g . Next, we turn our attention to the instrumental variables that can be controlled in an atom probe analysis.…”

Atom probe tomography spatial reconstruction: Status and directions

“…A natural goal would be to re-compute the exact trajectory of each ion based on an atomically-defined specimen inserted within a simulation model, and hence allow overcoming the distortions induced by the simplicity of the projection used in the current paradigm. Haley et al used a finite-element-based electrostatic computation of the distribution of the electric field generated by specimens [101], the shape of which had been extracted, in threedimensions, using electron tomography techniques [102,103]. They discussed the complexity of implementing such methods, which do not account for the detailed atomic structure of the emitting surface (near field).…”

Combining structural and chemical information at the nanometer scale by correlative transmission electron microscopy and atom probe tomography

“…After the introduction of TEM for the target preparation of grain boundaries in the apex of FIM samples by Papazian [29], Kraukauer and Seidman [18] developed a setup in the 1990s that enabled double-tilt TEM operation followed by onedimensional atom probe measurements on individual atom probe (AP) tips. More recent and sophisticated approaches have allowed for TEM tomography on individual AP tips prior to APT [13,2], for the purpose of optimization of the reconstruction parameters. In recent years, experimental setups capable of holding several atom probe tips at once have been developed, drastically increasing specimen throughput [11,12].…”