A Brief Overview of Atom Probe Tomography Research

Abstract

Atom probe tomography (APT) has been fast rising in prominence over the past decade as a key tool for nanoscale analytical characterization of a range of materials systems. APT provides three-dimensional mapping of the atom distribution in a small volume of solid material. The technique has evolved, with the incorporation of laser pulsing capabilities, and, combined with progress in specimen preparation, APT is now able to analyse a very range of materials, beyond metals and alloys that used to be its core applications. The present article aims to provide an overview of the technique, providing a brief historical perspective, discussing recent progress leading to the state-of-the-art, some perspectives on its evolution, with targeted examples of applications.Key Words: Atom probe tomography, Field evaporation, Materials characterization, Microscopy, Nanoscale Gault B 118The specimen is progressively destroyed, almost atom-byatom, and the atom probe microscope collects the timeof-flight and impact position of each ion. Processing of the data translates the time-of-flight into a mass-to-charge ratio, and the position is used to build a tomographic, atomically resolved image of the evaporated volume (Bas et al., 1995;Larson et al., 2013), represented as a point-cloud where every point is an atom that has been elementally identified and repositioned with a high degree of precision (Gault et al., 2010b). INSTRUMENTAL DESIGNEarly designs of the technique, usually referred to as atomprobe field ion microscopes or one-dimensional (1D) atom probe (Miller, 2000;Müller et al., 1968), had a very narrow field-of-view and really only provided linear compositional measurement in the depth of the sample, within a region of interest located by field-ion microscopy (Brenner & Goodman, 1971). APT was truly enabled by the implementation of position-sensitive, time-resolved particle detectors by Cerezo et al. (1988) followed by Blavette et al. (1993), and modern microscopes are equipped with delayline detectors (Da Costa et al., 2005; Jagutzki et al., 2002). The incorporation of micro-channel plates (MCPs) in the design of such detectors, to convert the impact of a single-ion into a cascade of up to millions of electrons, limits the efficiency approximately to the open area of the MCPs, so between 50%~80%. The MCPs are operated in saturated mode, which ensures almost no mass or atomic number sensitivity for ions in the range of 2~3 kV up to 15~20 kV up to several hundreds of Da, and the loss of ions is therefore nonspecific and assumed to be random and hence not affecting the technique's capacity to precisely measure the elemental composition. In order to increase the mass resolution of the technique, limited by the energy spread of the emitted ions, reflectron-lenses were fitted onto atom probes (Bémont et al., 2003;Cerezo et al., 1998;Panayi, 2006). A reflectron acts as an electrostatic mirror: ions penetrate inside a region containing a well-defined electric field in which ions are progressively slowed down until they are returne...

Chalcogenide Thermoelectrics Empowered by an Unconventional Bonding Mechanism

“…Indeed, a study of bond breaking using atom probe tomography [53,54] supports the idea of an exceptional bonding mechanism. To this end, laser-assisted atom probe tomography has been utilized to study bond rupture.…”

Correlative Spectromicroscopy and Tomography for Biomedical Applications Involving Electron, Ion, and Soft X-ray Microscopies

“…Atom probe tomography (APT) is a 4D tomographic technique capable of mapping element distributions with atomic spatial resolution and parts per million chemical sensitivity. This technique is based on the evaporation of surface atoms triggered by a pulsed electric field [14]. With the incorporation of laser pulsing and improvements in sample preparation, APT has expanded its application base from metal and semiconductor materials to non-conductive biomaterials and minerals [15,16].…”

Identification of core/shell structure in Cd‐Zn‐Se QDs inside silicate glasses using 3D elemental distribution analysis

“…17,18 Atom probe tomography (APT) can provide three-dimensional analytical mapping of materials with atomic scale resolution around 0.1-0.3 nm in depth and 0.3-0.5 nm in lateral direction. [19][20][21] This tomographic reconstruction imaging derived from field ionization can give information such as atomic clustering, short-range order, interface, structure, and composition in various materials. [22][23][24] However, a conventional voltage-pulsed atom probe method has limitation for insulators since their low electrical conductivity seriously distorts the evaporation of ions from the specimens.…”

“…Atom probe tomography (APT) can provide three‐dimensional analytical mapping of materials with atomic scale resolution around 0.1‐0.3 nm in depth and 0.3‐0.5 nm in lateral direction 19‐21 . This tomographic reconstruction imaging derived from field ionization can give information such as atomic clustering, short‐range order, interface, structure, and composition in various materials 22‐24 .…”