Atom probe tomography is a unique characterization technique that facilitates three-dimensional visualization as well as in‐depth analysis of nano‐scale features at near‐atomic scale resolution (lateral resolution: 0.3-0.5 nm and depth resolution 0.1-0.3 nm), 3D information about the position of each atom in the analyzed sample and chemical sensitivity down to atomic parts per million. A sharp tip sample is prepared using Focused Ion Beam (FIB).

Prepared sample is then cooled to ~ 50K in the analysis chamber of the microscope. The tip is biased at high DC voltage (3-15 kV) and due to the sharpness of the tip, high electrostatic field can be generated. This field is sufficient to field evaporate atoms from the surface of the sample. By applying voltage pulse or laser pulse the field evaporated ions are projected on the position sensitive detector. Time (Time of flight measurement) taken by the ions to reach the detector is noted and the x, y position of the ions is detected. This allows to reconstruct the original position of the evaporated atoms in the analyzed sample.