Atom‐Probe Tomography and Nanosciences

Abstract

The design of Atom probe tomography (APT) at Oxford and Rouen universities 25 years ago has been an outstanding breakthrough in the microscopy world. APT is the only analytical microscope able to provide 3D images of a material at the atomic scale [1]. Because of its ultimate spatial resolution (0.1 nm in depth, a few tenths of a nm at the sample surface), combined with its quantitativity in composition measurements, APT has played a major role for the investigation of the segregation of impurities to crystal defects or of the early stages of phase separation in solids. APT was the first to show Cottrell atmospheres (tiny clouds of impurity atoms around dislocations in crystals) at the atomic‐scale in the dimensions of space [2]. A new breakthrough has been achieved ten years ago with the implementation of ultrafast pulsed laser (duration < 1ps) to atom probe tomography [3]. This new generation of instrument, designed in our lab and abroad, has made it possible the analysis of semi‐conductors (figure 1) and oxides that are key materials in micro‐electronics and nanosciences [4]. This major innovation with the use of FIB ion milling (focused ion beam) to prepare samples in the region of interest opened a new insight in many fields of nanoscience related to nano‐wires [5], nanostructured magnetic thin films [6], heavily‐doped ultra‐shallow junctions in microelectronics [7]. One of the biggest challenge being the atomic‐scale reconstruction of MOSFET transistors [8,9]. Unique capabilities of atom probe tomography in nanoscience and salient findings will be highlighted on the basis of some selected illustrations. 3D APT reconstructions related to phase separation in GeMn self‐organised thin films (figure 2) will be confronted to atomistic Kinetic Monte Carlo simulations conducted on rigid lattice [6].