Atomistic simulations of field assisted evaporation in atom probe tomography

Atom probe tomography (APT) is an extremely powerful technique for determining the three-dimensional structure and chemical composition of a given sample. Although it is designed to provide images of material structure with atomic scale resolution, reconstruction artifacts, well-known to be present in reconstructed images, reduce their accuracy. No existing simulation technique has been able to describe the origin of these artifacts. Here we develop a simulation technique which allows for atomistic simulations of the atom emission process in the presence of high electric fields in APT experiments. Our code combines hybrid concurrent electrodynamics—molecular dynamics and a Monte Carlo approach. We use this technique to demonstrate the atom-level origin of artifacts in APT image reconstructions on examples of inclusions and voids in investigated samples. The results show that even small variations in the surface topology give rise to distortions in the local electric field, limiting the accuracy of conventional APT reconstruction algorithms.