Interpreting Atom Probe Data from Oxide–Metal Interfaces

Abstract

Understanding oxide-metal interfaces is crucial to the advancement of materials and components for many industries, most notably for semiconductor devices and power generation. Atom probe tomography provides three-dimensional, atomic scale information about chemical composition, making it an excellent technique for interface analysis. However, difficulties arise when analyzing interfacial regions due to trajectory aberrations, such as local magnification, and reconstruction artifacts. Correlative microscopy and field simulation techniques have revealed that nonuniform evolution of the tip geometry, caused by heterogeneous field evaporation, is partly responsible for these artifacts. Here we attempt to understand these trajectory artifacts through a study of the local evaporation field conditions. With a better understanding of the local evaporation field, it may be possible to account for some of the local magnification effects during the reconstruction process, eliminating these artifacts before data analysis.

How solute atoms control aqueous corrosion of Al-alloys

“…Segregation of Zn and Cu is shown at the oxide/metal interface with Zn up to 28 at.% and Cu up to 6 at.%, which is far beyond the solubility limit of Zn (0.85 at.%) and Cu (0.02 at.%) 26 in Al at room temperature. We note that the field change at the oxide/metal interface might induce elemental diffusion at the interface in the APT experiments, a phenomenon that has been reported for light elements such as H, N, C, and O 27,28 . Given the significant amounts observed here of the heavy metals Zn (28 at.%) and Cu (6 at.%), we are inclined to believe that evaporation-induced migration might not have or only very moderately altered the elemental distribution features at the oxide interface.…”

Atom Probe Tomography of Encapsulated Hydroxyapatite Nanoparticles

“…[ 13b–e ] However, the materials used for ALD in most labs are typically limited to oxides. An oxide matrix can generate undesirably complex mass spectra in APT with high chance of peak overlap, [ 16 ] whereas a high atomic mass and/or simple spectrum metal matrix such as gold would exhibit an advantage in the mass spectrum analysis incorporating a NP with multiple low mass to charge ratio (M/Z) peaks. Yet, simultaneously, large field differences between materials lead to undesirable ion trajectory aberrations and hence questionable reconstructed APT data at the heterogeneous interfaces between the encapsulating matrix and the embedded NPs.…”

Interpreting the Presence of an Additional Oxide Layer in Analysis of Metal Oxides–Metal Interfaces in Atom Probe Tomography

“…Numerous examples of APT analyses of oxide/metal interfaces can be found in the literature, examples of devices with Fe/MgO/Fe multilayers − or Co-doped ZnO, oxidation studies with RhO 2 formation from a Pt–Rh alloy, , or oxide dispersion-strengthened (ODS) steels, , oxides grown in a Ni-supper alloy, or switching behavior in a TiO 2 /NbO 2 /Ta structure . The challenges in reconstruction of interfacial regions in APT due to trajectory aberrations due to local magnification are well documented. ,− However, one might wonder about the chemistry of the oxide/metal interfaces in these selected examples and how the measurements might modify the structures.…”