Nanoscale Localization of an Atom Probe Tip through Electric Field Mapping

摘要

This work concerns one of the main challenges in atom probe tomography (APT) of heterogeneous systems, that is, the reliable placement of evaporated atoms in the reconstructed volume with subnanometer precision. The accurate determination of the nanoscale needle specimen shape constitutes an essential requirement to overcome this challenge as it enables one to include the details of the tip shape in the reconstruction algorithms distortions. Recently, scanning probe microscopy (SPM) has been pioneered as a promising approach to capture the topography of the APT specimen in three dimensions. However, reaching the unusual tip-on-tip measurement configuration requires approaching the specimen with the SPM probe in a highly controlled manner to avoid any damage to probe or specimen. Here, we propose a new method to align the SPM probe with an APT tip through a measurement of the electrostatic interaction between both. The method is free of any mechanical interaction between both tips prior to surface imaging and is applicable for all possible probe geometries. Additional insights into the resolution through a simulation of the electrostatic interaction between the SPM probe and a biased APT tip are provided. In prospect, this study opens doors to probe the electric field around an APT tip in three dimensions.