Time-resolved acquisition technique for elemental mapping by energy-filtering TEM

Terada, Shohei; Aoyama, Takashi; Yano, Fumiko; Mitsui, Yasuhiro

doi:10.1093/jmicro/50.2.83

Cited by 13 publications

(12 citation statements)

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“…From the theoretical consideration there should only be an effect on the signal intensity in the interface region whereas the total sum of the intensity should stay the same. However, similar results for merged EFTEM images were reported by Terada et al [4]. Beside the change in signal intensity an increase in the inclination of the slopes can be observed, especially for the 2 nm layers.…”

Section: Resultssupporting

confidence: 90%

“…1). To avoid this and other detrimental effects caused by long acquisition times, one can divide the necessary exposure time, take several sub-images with shorter exposure times, and merge these a posteriori after drift-correction [3,4]. Due to the necessity for the position fitting of the sub-images with a potentially low signal-to-noise ratio (SNR), the drift-correction can be quite time consuming or error-prone, especially if a high number of subimages has to be merged [5].…”

Section: Introductionmentioning

confidence: 99%

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Optimization of EFTEM image acquisition by using elastically filtered images for drift correction

Heil

Kohl

2010

Ultramicroscopy

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Optimization of EFTEM image acquisition by using elastically filtered images for drift correction

Heil

Kohl

2010

Ultramicroscopy

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“…is not a true Ce elemental contrast. From the discussion presented above, it is evident that the best technique to acquire an elemental map at the intermediate-loss region is the EFTEM Spectrum Imaging (EFTEM SI) (Schaffer, et al, 2008;Schaffer, et al, 2006;Terada, et al, 2001;Watanabe & Allen, 2012). This technique involves acquiring a series of EFTEM images with a narrow slit, and with the spectrometer continuously stepping through energies (or energy-loss), from a region representing the edge to the background region prior to the edge onset.…”

Section: Resultsmentioning

confidence: 99%

Elemental Mapping of Labeled Biological Specimens at Intermediate Energy Loss in an Energy-Filtered TEM acquired using a Direct Detection Device

Ramachandra

Mackey

et al. 2020

Preprint

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The multi-color or single-color EM that was developed previously, by the pseudo-colored overlay of the core-loss or high-loss EFTEM elemental map/s of the lanthanide onto the conventional image, the lanthanide chelates conjugated to diaminobenzidine being sequentially deposited as a result of selective oxidization by orthogonal photosensitizers / peroxidases. The synthesis of the new second generation lanthanide DABs, which contains 4 times more lanthanide per DAB, gives significant signal amplification and enabling collection of elemental maps at much lower energy-loss regions more favorable. Under the same experimental conditions, acquiring EFTEM elemental maps for the lanthanides at the lower energy-loss of N4,5 edge instead of the core-loss M4,5 edge, provides ~4x increase in signal-to-noise and ~2x increase in resolution. The higher signal at the N4,5 edge, also allows for more sophisticated technique of EFTEM spectrum Image for the acquisition of elemental maps with very high signal fidelity.

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“…We have already reported a time-resolved technique for acquiring both 2D-EELS and spatially resolved EELS images using the TEM-EELS system in order to minimize the influences of the sample and energy drift on those images Terada et al, 2001Terada et al, , 2002!. In the case of 2D-EELS images, 10 energy-filtered images were taken at the three energy regions of post-edge, pre2-edge and pre1-edge, respectively.…”

Section: Time-resolved Technique Acquiring 2d-eels and Spatially Resomentioning

confidence: 99%

Searching Ultimate Nanometrology for AlOx Thickness in Magnetic Tunnel Junction by Analytical Electron Microscopy and X-ray Reflectometry

et al. 2005

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Practical analyses of the structures of ultrathin multilayers in tunneling magneto resistance (TMR) and Magnetic Random Access Memory (MRAM) devices have been a challenging task because layers are very thin, just 1-2 nm thick. Particularly, the thinness (approximately 1 nm) and chemical properties of the AlOx barrier layer are critical to its magnetic tunneling property. We focused on evaluating the current TEM analytical methods by measuring the thickness and composition of an AlOx layer using several TEM instruments, that is, a round robin test, and cross-checked the thickness results with an X-ray reflectometry (XRR) method. The thickness measured by using HRTEM, HAADF-STEM, and zero-loss images was 1.1 nm, which agreed with the results from the XRR method. On the other hand, TEM-EELS measurements showed 1.8 nm for an oxygen 2D-EELS image and 3.0 nm for an oxygen spatially resolved EELS image, whereas the STEM-EDS line profile showed 2.5 nm in thickness. However, after improving the TEM-EELS measurements by acquiring time-resolved images, the measured thickness of the AlOx layer was improved from 1.8 nm to 1.4 nm for the oxygen 2D-EELS image and from 3.0 nm to 2.0 nm for the spatially resolved EELS image, respectively. Also the observed thickness from the EDS line profile was improved to 1.4 nm after more careful optimization of the experimental parameters. We found that EELS and EDS of one-dimensional line scans or two-dimensional elemental mapping gave a larger AlOx thickness even though much care was taken. The reasons for larger measured values can be found from several factors such as sample drift, beam damage, probe size, beam delocalization, and multiple scattering for the EDS images, and chromatic aberration, diffraction limit due to the aperture, delocalization, alignment between layered direction in samples, and energy dispersion direction in the EELS instrument for EELS images. In the case of STEM-EDS mapping with focused nanoprobes, it is always necessary to reduce beam damage and sample drift while trying to maintain the signal-to-noise (S/N) ratio as high as possible. Also we confirmed that the time-resolved TEM-EELS acquisition technique improves S/N ratios of elemental maps without blurring the images.

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Time-resolved acquisition technique for elemental mapping by energy-filtering TEM

Cited by 13 publications

References 0 publications

Optimization of EFTEM image acquisition by using elastically filtered images for drift correction

Optimization of EFTEM image acquisition by using elastically filtered images for drift correction

Elemental Mapping of Labeled Biological Specimens at Intermediate Energy Loss in an Energy-Filtered TEM acquired using a Direct Detection Device

Searching Ultimate Nanometrology for AlOx Thickness in Magnetic Tunnel Junction by Analytical Electron Microscopy and X-ray Reflectometry

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