Abstract:
Scanning transmission electron microscopy (STEM) boosted by aberration-correction technology has made it possible to directly image atoms at localized volumes of many materials and devices especially at interface regions where very interesting properties emerges. In STEM imaging, a very finely focused electron probe is scanned across the specimen and the transmitted and/or scattered electrons at each raster position are detected by the post-specimen detector(s) to form images.
STEM image contrast is known to be strongly dependent on the detector geometries, and in turn we gain flexibility in determining the contrast characteristics of the STEM images by controlling the detector geometry. By elaborating special detector geometries, we can not only image atomic structures of materials, but also can image local electromagnetic fields inside materials through differential phase contrast (DPC) imaging techniques [1]. We have been continuously developing area detectors that are capable of atomic-resolution STEM imaging. By applying these area detectors, atomic-resolution DPC STEM imaging has been realized [2,3].
We found that DPC STEM imaging is very powerful to directly characterize many interesting internal electromagnetic structures such as pn junctions in semiconductor devices [4], polar oxide interfaces and magnetic Skyrmions [5] which cannot be observed by normal STEM imaging techniques using annular type detectors. In addition, new STEM development will be shown in the presentation.
Reference
[1] N. Shibata et al., Acc. Chem. Res., 50, 1502-1512 (2017).
[2] N. Shibata et al., Nature Phys., 8, 611-615 (2012).
[3] N. Shibata et al., Nature Comm. 8, 15631 (2017).
[4] N. Shibata et al., Sci. Rep., 5, 10040 (2015).
[5] T. Matsumoto et al., Sci. Adv. 2, e1501280 (2016)
Brief Bio:
Dr. Naoya Shibata received a PhD in Materials Science in 2003 at University of Tokyo. He was a JSPS Research Fellow at Oak Ridge National Laboratory (2003-2004). He was a Research Associate in Institute of Engineering Innovation at the University of Tokyo (2004-2007) and was an Assistant Professor (2007-2011) and an Associate Professor (2011-2017) and now is a Professor in the University of Tokyo. His research focuses on the development of new imaging techniques in scanning transmission electron microscopy and their application to grain boundaries and interfaces in oxide materials.