期刊
ULTRAMICROSCOPY
卷 151, 期 -, 页码 160-167出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ultramic.2014.09.013
关键词
STEM; Pixelated detectors; Ptycography; Phase contrast; Chromatic aberrations; DPC; ABF
类别
资金
- EPSRC through the UK National Facility for Aberration-Corrected STEM (SuperSTEM)
- EPSRC [EP/K032518/1]
- Division of Materials Sciences and Engineering of the U.S. department of Energy
- European Union [312483]
- EPSRC [EP/K032518/1, EP/M010708/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/M010708/1, EP/K032518/1] Funding Source: researchfish
We demonstrate a method to achieve high efficiency phase contrast imaging in aberration corrected scanning transmission electron microscopy (STEM) with a pixelated detector. The pixelated detector is used to record the Ronchigram as a function of probe position which is then analyzed with ptychography. Ptychography has previously been used to provide super-resolution beyond the diffraction limit of the optics, alongside numerically correcting for spherical aberration. Here we rely on a hardware aberration corrector to eliminate aberrations, but use the pixelated detector data set to utilize the largest possible volume of Fourier space to create high efficiency phase contrast images. The use of ptychography to diagnose the effects of chromatic aberration is also demonstrated. Finally, the four dimensional dataset is used to compare different bright field detector configurations from the same scan for a sample of bilayer graphene. Our method of high efficiency ptychography produces the clearest images, while annular bright field produces almost no contrast for an in-focus aberration-corrected probe. (C) 2014 Elsevier B.V. All rights reserved
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