Applications of a novel electron energy filter combined with a hybrid-pixel direct electron detector for the analysis of functional oxides by STEM/EELS and energy-filtered imaging

Alicia Ruiz Caridad; Rolf Erni; Alexander Vogel; Marta D Rossell

doi:10.1016/j.micron.2022.103331

Applications of a novel electron energy filter combined with a hybrid-pixel direct electron detector for the analysis of functional oxides by STEM/EELS and energy-filtered imaging

Micron. 2022 Sep:160:103331. doi: 10.1016/j.micron.2022.103331. Epub 2022 Jul 21.

Authors

Alicia Ruiz Caridad¹, Rolf Erni², Alexander Vogel¹, Marta D Rossell¹

Affiliations

¹ Electron Microscopy Center, Empa - Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
² Electron Microscopy Center, Empa - Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland. Electronic address: rolf.erni@empa.ch.

PMID: 35882179
DOI: 10.1016/j.micron.2022.103331

Abstract

The performance and suitability of a new electron energy filter in combination with a hybrid pixel, direct electron detector for analytical (scanning) transmission electron microscopy are demonstrated using four examples. The STEM-EELS capabilities of the CEOS Energy Filtering and Imaging Device (CEFID) were tested with focus on weak signals and high spatio-temporal resolution. A multiferroic, multilayer structure of REMnO₃ (RE = Yb, Er, Tb, Y), grown on yttria-stabilized zirconia (YSZ), is used to exemplify that this new instrumental setup produces valuable electron energy-loss spectroscopy (EELS) data at high energy losses even when using short acquisition times, providing detailed chemical information about the interfaces in this complex multilayer sample. Another functional oxide, namely a ferromagnetic La₂NiMnO₆ thin film grown on SrTiO₃, demonstrates that atomically resolved spectrum images can be recorded, using short dwell times and moderate beam currents in order to warrant the integrity of the sample. In a third example, inhomogeneously Er-doped YSZ shows by EELS spectrum imaging that elements at low concentrations can be detected semi-quantitatively, uncovering the expected layered Er distribution but revealing substantial interdiffusion. In a final example, we simply demonstrate that the hybrid pixel detector in combination with the energy filter can also be used for energy-filtered imaging and thus for elemental mapping complementary to EELS in scanning transmission mode.

Keywords: Analytical scanning transmission electron microscopy; Electron energy-loss spectroscopy (EELS); Energy filter; Energy-filtered imaging (EFI); Functional oxides; Hybrid-pixel, direct electron detector.