Optimal experimental design for nano-particle atom-counting from high-resolution STEM images

Backer, Annick De; wael, Annelies De; Gonnissen, J.; Aert, Sandra Van

doi:10.1016/j.ultramic.2014.10.015

Cited by 42 publications

(44 citation statements)

References 45 publications

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“…Experimentally, smaller detector angles have been shown to demonstrate lower sensitivity to mis-tilt [28], which has been backed up by a statistical analysis of accuracy in atom assignments [29]. In this paper we show that it is possible to optimise the experimental parameters in order to minimise quantification errors should small sample mis-tilts occur.…”

Section: Introductionmentioning

confidence: 78%

Optimal ADF STEM imaging parameters for tilt-robust image quantification

et al. 2015

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An approach towards experiment design and optimisation is proposed for achieving improved accuracy of ADF STEM quantification. In particular, improved robustness to small sample mis-tilts can be achieved by optimising detector collection and probe convergence angles. A decrease in cross section is seen for tilted samples due to the reduction in channelling, resulting in a quantification error, if this is not taken into account. At a smaller detector collection angle the increased contribution from elastic scattering, which initially increases with tilt, can be used to offset the decrease in the TDS signal.

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Section: Introductionmentioning

confidence: 78%

Optimal ADF STEM imaging parameters for tilt-robust image quantification

et al. 2015

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“…Since each depth location corresponds to one hypothesis, multiple hypothesis tests have been used which quantify the overlap of multiple probability functions as compared to the binary case shown in Fig. 5 [20]. In this manner, the probability of error as a function of the incident electron dose is determined for the 5-, 10-and 20-atom-thick columns, shown in Fig.…”

Section: Possibilities To Locate the Depth Position Of A Au Impuritymentioning

confidence: 99%

The atomic lensing model: New opportunities for atom-by-atom metrology of heterogeneous nanomaterials

et al. 2019

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The atomic lensing model has been proposed as a promising method facilitating atom-counting in heterogeneous nanocrystals [1]. Here, image simulations will validate the model, which describes dynamical diffraction as a superposition of individual atoms focussing the incident electrons. It will be demonstrated that the model is reliable in the annular dark field regime for crystals having columns containing dozens of atoms. By using the principles of statistical detection theory, it will be shown that this model gives new opportunities for detecting compositional differences.

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“…Beyond around eight atoms, the peak intensity signal saturates and it becomes harder to distinguish between increasing number of atoms. Since the cross-section measure has shown a monotonic increment with respect to increasing number of atoms [29,31,32,37] and with respect to increasing average atomic column weight [27,28,30] and robust to probe parameters [30,33], we consider this a suitable measure for quantitative ADF analysis and use this through the remainder of this work.…”

Section: Measurement Of the Inner And Outer Angle Of The Detectormentioning

confidence: 99%

Quantitative STEM normalisation: The importance of the electron flux

et al. 2015

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Annular dark-field (ADF) scanning transmission electron microscopy (STEM) has become widely used in quantitative studies based on the opportunity to directly compare experimental and simulated images. This comparison merely requires the experimental data to be normalised and expressed in units of 'fractional beam-current'. However, inhomogeneities in the response of electron detectors can complicate this normalisation. The quantification procedure becomes both experiment and instrument specific, requiring new simulations for the particular response of each instrument's detector, and for every camera-length used. This not only impedes the comparison between different instruments and research groups, but can also be computationally very time consuming. Furthermore, not all image simulation methods allow for the inclusion of an inhomogeneous detector response. In this work, we propose an alternative method for normalising experimental data in order to compare these with simulations that consider a homogeneous detector response. To achieve this, we determine the electron flux distribution reaching the detector by means of a camera-length series or a so-called atomic column cross-section averaged convergent beam electron diffraction (XSACBED) pattern. The result is then used to determine the relative weighting of the detector response. Here we show that the results obtained by this new electron flux weighted (EFW) method are comparable to the currently used method, while considerably simplifying the needed simulation libraries. The proposed method also allows one to obtain a metric that describes the quality of the detector response in comparison with the 'ideal' detector response.

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Optimal experimental design for nano-particle atom-counting from high-resolution STEM images

Cited by 42 publications

References 45 publications

Optimal ADF STEM imaging parameters for tilt-robust image quantification

Optimal ADF STEM imaging parameters for tilt-robust image quantification

The atomic lensing model: New opportunities for atom-by-atom metrology of heterogeneous nanomaterials

Quantitative STEM normalisation: The importance of the electron flux

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