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Title: Efficient phase contrast imaging in STEM using a pixelated detector. Part 1: Experimental demonstration at atomic resolution

In this paper, 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. In conclusion, 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.
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [1]
  1. Daresbury Lab. (United Kingdom). EPSRC SuperSTEM Facility; Univ. of Oxford (United Kingdom). Dept. of Materials
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  3. Univ. of Oxford (United Kingdom). Dept. of Materials
  4. Nion Co., Kirkland, WA (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC05-00OR22725; EP/K032518/1; 312483–ESTEEM2
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 151; Journal ID: ISSN 0304-3991
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Daresbury Lab. (United Kingdom)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Engineering and Physical Sciences Research Council (EPSRC) (United Kingdom); European Union (EU)
Contributing Orgs:
Univ. of Oxford (United Kingdom)
Country of Publication:
United States
36 MATERIALS SCIENCE; 47 OTHER INSTRUMENTATION STEM; Pixelated detectors; Ptycography; Phase contrast; Chromatic aberrations; DPC; ABF