Studies of x-ray localization and thickness dependence in atomic-scale elemental mapping by STEM energy-dispersive x-ray spectroscopy using single-frame scanning method

Abstract

The delocalization of x-ray signals limits the spatial resolution in atomic-scale elemental mapping by scanning transmission electron microscopy (STEM) using energy-dispersive x-ray spectroscopy (EDS). In this study, using a SrTiO [001] single crystal, we show that the x-ray localization to atomic columns is strongly dependent on crystal thickness, and a thin crystal is critical for improving the spatial resolution in atomic-scale EDS mapping. A single-frame scanning technique is used in this study instead of the multiple-frame technique to avoid peak broadening due to tracking error. The strong thickness dependence is realized by measuring the full width at half maxima (FWHM) as well as the peak-to-valley (P/V) ratio of the EDS profiles for Ti K and Sr K + L, obtained at several crystal thicknesses. A FWHM of about 0.16 nm and a P/V ratio of greater than 7.0 are obtained for Ti K for a crystal thickness of less than 20 nm. With increasing crystal thickness, the FWHM and P/V ratio increases and decreases, respectively, indicating the advantage of using a thin crystal for high-resolution EDS mapping.

Atomic‐Scale Control of Electronic Structure and Ferromagnetic Insulating State in Perovskite Oxide Superlattices by Long‐Range Tuning of BO6 Octahedra

“…Chemical sharpness was ascertained using atomically resolved energy-dispersive X-ray spectroscopic (EDS) mapping across the LBMO/STO interfaces ( Figure S2b, Supporting Information). By considering geometrical roughness and projection effect, [37][38][39] the interfacial intermixing was determined to be around 1 uc.…”

Atomic structures of Ti‐doped α‐Al2O3 Σ13 grain boundary with a small amount of Si impurity

“…The relative cation concentrations of Al, Ti, and Si are estimated to be 89.5 cation %, 9.7 cation % (4.6 atoms/nm 2 ), and 0.8 cation % (0.4 atoms/ nm 2 ), respectively, where the values in atoms/nm 2 indicate the chemical excess at grain boundary plane calculated by referring the previous reports. 22,37 Note that the delocalization of the emitted X-ray signal from a sample is inevitable in atomic-scale STEM-EDS mapping, 38 and we therefore estimated the grain boundary cation concentration by averaging over within a sufficiently large width of 1 nm. As we have noted, the amount of Si impurity is small and therefore the type-I structure could be considered as a simple Ti segregated grain boundary by substituting the Al site of the G(O) structure.…”

Advances and Applications of Atomic-Resolution Scanning Transmission Electron Microscopy

“…A quantitative interpretation of atomic-resolution XEDS maps, however, require detailed simulations (Lugg et al, 2015 b ; Chen et al, 2016; MacArthur et al, 2017). Lu et al (2018) used a single-frame scanning technique rather than an averaging multiple-frame approach to avoid peak broadening (Fig. 24).…”