Abstract text (incl. figure legends and references)

Optimizing ion species for specific (S)TEM sample preparation tasks is not only becoming common with multi-ion species plasma FIB, but rather, essential as our understanding from experience and simulation data grows. Xenon ions provide a high sputter yield and are excellent for large 3D-volume-data-acquisition and correlated microscopy applications. Reactive oxygen ion beam processing has proven to dramatically improve milling quality for carbon-carbon bonding materials by smoothing the cut-face very effectively during sputtering. In this presentation, recent progress of low-energy-focused-argon ion beam cleaning is explored from trials with a Helios 5 Hydra Plasma FIB for TEM specimen preparation. Argon ion beam can be used down to 500 eV for specimen preparation, which is producing lower damage in finished samples.

Ions species selection is critical for near "damage-free" TEM specimen preparation. Xenon plasma FIB first opened an opportunity for "gallium-free" TEM specimen preparation and had a benefit of lower amorphous layer thickness than gallium. However, Xenon ions induce higher vacancy-density in target materials. With conventional gallium FIB, there is a challenge to reduce or eliminate gallium in TEM specimen. Unfortunately, gallium implantation commonly leads to reactions and migration with many materials (e.g., steel, aluminum alloy, GaN/AlGN etc).

Experimentation with the Helios Hydra for making (S)TEM samples has confirmed that the focused argon ion beam is suitable for near damage-free TEM specimen preparation guided by the investigation of ion-solid interaction SRIM data [1]. With Plasma FIB argon ion energy at 500 eV, it is becoming routine to produce near "damage-free" TEM specimens of these reactive materials which opens new opportunities for better material structure-property-function investigation.

[1] C. Jiao, J. Graham, Xu Xu, T. Burnett, and B. van Leer. Low Energy 500 eV Focused Argon Ion Beam Provided by Multi-Ions Species Plasma FIB for Material Science Sample Preparations. Microsc.Microanal. 27 (Spupl 1). 2021