Scanning Precession Electron Tomography (SPET) for Structural Analysis of Thin Films along Their Thickness

Accurate structure analysis of epitaxial perovskite thin films is a fundamental step towards the ability to tune their physical properties as desired. Precession-assisted electron diffraction tomography (PEDT) has proven to be an effective technique for performing ab initio structure solutions and refinements for this class of materials. As the film thickness or the region of interest (ROI) decrease in size, the capacity to collect PEDT data with smaller electron beams is a key parameter and ROI tracking becomes a major issue. To circumvent this problem, we considered here an alternative approach to acquiring data by combining PEDT with a scan over an area, extracting the intensities collected at different positions and using them to perform accurate structure refinements. As a proof of concept, a Scanning Precession Electron Tomography (SPET) experiment is performed on a 35 nm thick perovskite PrVO3(PVO) film deposited on a SrTiO3 (STO) substrate. This way, it was possible to detect small changes in the PVO structure along the film thickness, from the variation in unit cell parameters to atomic positions. We believe that SPET has the potential to become the standard procedure for the accurate structure analysis of ROIs as small as 10 nm.

Automated summary

Accurate structure analysis of epitaxial perovskite thin films is achieved through Scanning Precession Electron Tomography (SPET), which combines PEDT with area scanning to extract intensity information and refine the structure. The SPET experiment successfully detects small changes in the structure of a 35 nm thick perovskite film, showcasing its potential as a standard procedure for accurate structure analysis of ROIs as small as 10 nm.