fs-laser preparation of half grid specimens for atom probe tomography and transmission electron microscopy

Michael Tkadletz, Maximilian Schiester, Helene Waldl, Georg Schusser, Michael Krause, Nina Schalk

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Abstract

For atom probe tomography (APT) and transmission electron microscopy (TEM) half grids are commonly applied as specimen carriers, serving as mount for focused ion beam (FIB) processed lift-outs. This technical note presents an alternative way to fabricate half grids directly from the material to be investigated using femtosecond (fs)-laser ablation. After cutting ∼200 µm thin in-plane and cross-plane slices from a TiN coated cemented carbide substrate using a precision cutting saw, two different half grid geometries, one suitable for APT and the other for TEM, were cut via fs-laser processing. Freestanding posts for APT were further sharpened and the areas intended for TEM were thinned top-down using the fs-laser system followed by final annular FIB milling of the APT and thinning of the TEM specimens. For proof of concept, the TiN APT half grid specimens in in- and cross-plane direction were successfully measured in voltage and laser-assisted mode, utilizing a local electrode atom probe, while electron transparency of the in- and cross-plane TEM half grid specimens was proven using a scanning electron microscope equipped with a scanning transmission electron microscopy (STEM) detector. The herein presented method is simple, fast and omits the necessity of a lift-out, reducing the complexity of FIB operations. Additionally, a frequently considered weak point of APT lift-out specimens, the Pt weld between specimen and half grid or microtip coupon is avoided, whilst a wide range of materials can be processed and consumables consumption is reduced. Thus, this work clearly demonstrates the great potential of fs-laser processing for APT and TEM specimen preparation.

Original languageEnglish
Article number108672
Number of pages6
JournalMaterials Today Communications
Volume39.2024
Issue numberJune
DOIs
Publication statusPublished - Jun 2024

Bibliographical note

Publisher Copyright: © 2024 The Authors

Keywords

  • APT
  • Coatings
  • Femtosecond laser ablation
  • Lift-out
  • TEM

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