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

Journal Article · 01 March 2018 · Ultramicroscopy

DOI: https://doi.org/10.1016/j.ultramic.2017.12.003 · OSTI ID:1421612

Lu, Ping ^[1]; Moya, Jaime M. ^[1]; Yuan, Renliang ^[2]; Zuo, Jian Min  ^[2]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Materials Science and Engineering

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 SrTiO₃ [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. In conclusion, 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.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1421612
• Alternate ID(s): OSTI ID: 1548906
• Report Number(s): SAND-2017-8813J; 656319
• Journal Information: Ultramicroscopy, Vol. 186, Issue C; ISSN 0304-3991
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English