PNNL

Abstract

Accurate reconstruction of spatial positions of field evaporated ions from detector patterns depends on a correct understanding of the tip shape evolution and evaporation laws of component atoms. Reconstruction artifacts introduced in the heterogeneous tip can be contributed by the assumption on homogeneous evaporation behavior. A level set method based specimen shape evolution model is developed in this study to simulate the evaporation of synthetic layered-structured atom probe tip. The simulation results of the shape evolution by the present level set model agree well with the literature data using other numerical approaches, i.e. finite difference method. The asymmetric evolving shape predicted by the level set model demonstrates that the complex evaporation behavior of heterogeneous tips and interface curvature can potentially lead to the tip reconstruction distortion. Compared with other shape evaporation methods the new method provides considerably higher resolution and computational efficiency with the aid of the intrinsic subgrid scale accuracy.