Recent developments of the tomographic atom probe

Abstract

Today material science requires the use of increasingly powerful tools in materials analysis. The last twenty years have witnessed the development of a number of analytical techniques. However, though the arsenal of these techniques is large today, only a few instruments allow both observation and analysis of materials at the nanometer level. One can mention secondary ions mass spectrometry technique (SIMS), scanning transmission electron microscopy coupled with electron energy loss spectrometry (STEM-EELS) and atomprobe techniques. In the SIMS technique, only in-depth spatial resolution can reach one nanometer since lateral spatial resolution is related to the incident ions beam diameter namelya few tenth of micrometers. On the contrary, in the STEM-EELS technique, the lateral spatial resolution can be as good as one nanometer while the in-depth spatial resolution is rather poor ; this last resolution is determined by the specimen thickness and therefore strongly depends on samples preparation.Atom-probe techniques makes it possible to investigate a material with both a high lateral and in-depth spatial resolution. Indeed, the spatial resolution reached with the atom-probe can be lower than one nanometer at the sample surface while being strictly equal to an atomic layer in-depth.