Regensburg 2022 – scientific programme
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DS: Fachverband Dünne Schichten
DS 1: Thin Film Properties: Structure, Morphology and Composition (XRD, TEM, XPS, SIMS, RBS, AFM, ...) 1
DS 1.4: Talk
Monday, September 5, 2022, 10:15–10:30, H14
Scattergram analysis and filtering of differential phase contrast STEM images — •Julius Bürger1,2, Maja Groll1,2, Thomas Riedl1,2, and Jörg K. N. Lindner1,2 — 1Nanostructuring, Nanoanalysis and Photonic Materials Group, Dept. of Physics, Paderborn University, Paderborn, Germany — 2Center for Optoelectronics and Photonics Paderborn (CeOPP), Paderborn, Germany
Differential phase contrast (DPC) in scanning transmission electron microscopy allows the imaging and quantification of electric fields in solid specimen by measuring the transferred (first) momentum perpendicular to the optical axis imposed on the beam by the specimen's electrostatic potentials. Owing to the high-resolution capability of modern Cs-corrected transmission electron microscopes, electric fields and charge densities can be revealed with sub-atomic resolution. However, the requirements are very high, since the field distributions being measured by a position sensitive detector are drastically influenced by numerous factors, such as the lens aberrations, dynamic diffraction effects, noises, and the detector response function. We demonstrate how these influences can be readily detected in a DPC image using the so-called scattergram, which is a two-dimensional histogram of all transferred momenta, and particularly focus on the effect of noise and detector rotation by comparing DPC measurements and simulations for Si [110] performed with a segmented annular quadrant detector. In this regard, we introduce a novel method, the scattergram filtering, revealing the position of characteristic features in DPC images.