Probe integrated scattering cross sections in the analysis of atomic resolution HAADF STEM images

E, H.; MacArthur, Katherine E.; Pennycook, Timothy J.; Okunishi, Eiji; D’Alfonso, Adrian J.; Lugg, Nathan; Allen, L. J.; Nellist, Peter D.

doi:10.1016/j.ultramic.2013.07.002

Cited by 127 publications

(52 citation statements)

References 48 publications

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“…From the HAADF image, atomic column intensities for Sr and Ti-O columns (I Sr and I Ti-O ) were measured by averaging intensities within a small disk, with a radius of one-fourth of a lattice constant of SrTiO 3 , around each atomic column position. This method has been demonstrated to be a very effective way to obtain quantitative structural information since the integrated intensity is robust to subtle changes in imaging parameters such as defocus, effective source size, convergence angle, image noise, and sample tilt, all of which are difficult to determine experimentally [30,31].…”

Section: Methodsmentioning

confidence: 99%

Direct Observation of Sr Vacancies inSrTiO3by Quantitative Scanning Transmission Electron Microscopy

et al. 2016

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Unveiling the identity, spatial configuration, and microscopic structure of point defects is one of the key challenges in materials science. Here, we demonstrate that quantitative scanning transmission electron microscopy (STEM) can be used to directly observe Sr vacancies in SrTiO 3 and to determine the atom column relaxations around them. By combining recent advances in quantitative STEM, including variableangle, high-angle annular dark-field imaging and rigid registration methods, with frozen phonon multislice image simulations, we identify which Sr columns contain vacancies and quantify the number of vacancies in them. Picometer precision measurements of the surrounding atom column positions show that the nearest-neighbor Ti atoms are displaced away from the Sr vacancies. The results open up a new methodology for studying the microscopic mechanisms by which point defects control materials properties.

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Section: Methodsmentioning

confidence: 99%

Direct Observation of Sr Vacancies inSrTiO3by Quantitative Scanning Transmission Electron Microscopy

et al. 2016

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“…Although ultrafast cameras89101112131415 are currently introduced to the field of low-angle STEM, our approach exhibits several advantages. As quantitative analyses of atomically resolved STEM intensities rely on Voronoi diagrams16, Gaussian mixture models1718 or probe integrated cross sections19, each atomic column must be sampled with a sufficient number of probe positions. Here, acquisition of the 2 K × 2 K data used for the measurement of composition, thickness and strain in GaNAs at atomic resolution took 5 min 40 s. Even with a pixelated, ultrafast detector operating at 2 kHz this recording would have taken 35 min and more than one hour at the more typical frame rate of 1 kHz.…”

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confidence: 99%

Materials characterisation by angle-resolved scanning transmission electron microscopy

Müller‐Caspary

Oppermann

Grieb

et al. 2016

Sci Rep

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Solid-state properties such as strain or chemical composition often leave characteristic fingerprints in the angular dependence of electron scattering. Scanning transmission electron microscopy (STEM) is dedicated to probe scattered intensity with atomic resolution, but it drastically lacks angular resolution. Here we report both a setup to exploit the explicit angular dependence of scattered intensity and applications of angle-resolved STEM to semiconductor nanostructures. Our method is applied to measure nitrogen content and specimen thickness in a GaNxAs1−x layer independently at atomic resolution by evaluating two dedicated angular intervals. We demonstrate contrast formation due to strain and composition in a Si- based metal-oxide semiconductor field effect transistor (MOSFET) with GexSi1−x stressors as a function of the angles used for imaging. To shed light on the validity of current theoretical approaches this data is compared with theory, namely the Rutherford approach and contemporary multislice simulations. Inconsistency is found for the Rutherford model in the whole angular range of 16–255 mrad. Contrary, the multislice simulations are applicable for angles larger than 35 mrad whereas a significant mismatch is observed at lower angles. This limitation of established simulations is discussed particularly on the basis of inelastic scattering.

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“…1(d)]. Unlike maximum column intensities, I col are insensitive to parameters that are difficult to determine, such as the effective source size, focus spread, scan noise, sample drift, and Debye-Waller factor [36], and thus allow for direct comparison of experimental I col to simulations [36]. [33]), shown as large filled circles in Fig.…”

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confidence: 99%

Three-Dimensional Imaging of Individual Dopant Atoms inSrTiO3

et al. 2013

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We report on three-dimensional (3D) imaging of individual Gd dopant atoms in a thin (∼2.3 nm) foil of SrTiO3, using quantitative scanning transmission electron microscopy. Uncertainties in the depth positions of individual dopants are less than 1 unit cell. The overall dopant concentration measured from atom column intensities agrees quantitatively with electrical measurements. The method is applied to analyze the 3D arrangement of dopants within small clusters containing 4-5 Gd atoms.

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Probe integrated scattering cross sections in the analysis of atomic resolution HAADF STEM images

Cited by 127 publications

References 48 publications

Direct Observation of Sr Vacancies inSrTiO3by Quantitative Scanning Transmission Electron Microscopy

Direct Observation of Sr Vacancies inSrTiO3by Quantitative Scanning Transmission Electron Microscopy

Materials characterisation by angle-resolved scanning transmission electron microscopy

Three-Dimensional Imaging of Individual Dopant Atoms inSrTiO3

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