A spherical-aberration-corrected 200kV transmission electron microscope

Haider, Max; Rose, H.; Uhlemann, Stephan; Schwan, Eugen; Kabius, B.; Urban, K.

doi:10.1016/s0304-3991(98)00048-5

Cited by 407 publications

(211 citation statements)

References 13 publications

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“…Modern transmission electron microscopes (TEM) allow imaging materials at a single atom resolution with acceleration voltages in the range of 20-300 kV [1][2][3] , foremost thanks to the practical realization of aberration correctors (AC) for transmission electron microscopy 4,5 . However, high electron doses are required for achieving a high enough signal to noise ratio for accurate detection of the atom position in the image.…”

Section: Introductionmentioning

confidence: 99%

Electron radiation damage mechanisms in 2D MoSe2

Lehnert¹,

Lehtinen²,

Algara‐Siller³

et al. 2017

Applied Physics Letters

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The contributions of different damage mechanisms in single-layer MoSe 2 were studied by investigating different MoSe 2 /graphene heterostructures by aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) at 80 keV. The damage cross-sections were determined by direct counting of atoms in the AC-HRTEM images. The contributions of damage mechanisms such as knock-on damage or ionization effects were estimated by comparing the damage rates in different heterostructure configurations, similarly to what has been earlier done with MoS 2 . The behaviour of MoSe 2 was found to be nearly identical to that of MoS 2 , which is an unexpected result, as the knock-on mechanism should be suppressed in MoSe 2 due to the high mass of Se as compared to S.

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Section: Introductionmentioning

confidence: 99%

Electron radiation damage mechanisms in 2D MoSe2

Lehnert¹,

Lehtinen²,

Algara‐Siller³

et al. 2017

Applied Physics Letters

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“…Applications of these techniques in the area of catalytic materials, functional oxides and electronic materials have emerged since the first aberrationcorrected microscopes were developed over 10 years ago [1][2][3][4][5]. New developments in commercial instruments have, furthermore, made it possible to significantly broaden the impact of these new technological developments.…”

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confidence: 99%

Applications of Aberration-corrected TEM and STEM in Complex Oxides and Nanostructured Materials

Lazar

Chang²,

Gunawan

et al. 2009

Microsc Microanal

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Aberration-corrected microscopy and new generations of instruments have the potential of significantly improving the development of new materials by providing superior imaging resolution, stability and spectroscopic capabilities. Applications of these techniques in the area of catalytic materials, functional oxides and electronic materials have emerged since the first aberrationcorrected microscopes were developed over 10 years ago [1][2][3][4][5]. New developments in commercial instruments have, furthermore, made it possible to significantly broaden the impact of these new technological developments. Here we report on example where aberration-corrected instruments have provided significant benefits in various areas of applications related to the study of electronic properties of complex oxides and nanoscale materials such as carbon nanotubes.Experiments were carried out with a FEI Titan 80-300 Cubed equipped with two aberration correctors and a monochromator. This instrument achieved an information limit of 0.65-0.6Å, a STEM information transfer of better than 0.7Å and an energy resolution in EELS of 0.13eV. STEM imaging of the multiferroic compound Bi 2 Fe x Cr y O 6 has revealed the well-resolved transition metal sites between Bi bi-layers suggesting, directly from the High-Angle Annular Dark-Field HAADF images, similarities with an Aurivillius-type structure for this material (figure 1) that provides new insight on the magnetic properties of the thin films [6]. Energy-loss spectroscopy measurements at the CrL 2-3 and FeL 2-3 edges were also used to determine the valence of the Fe and Cr atoms. Phase contrast images also revealed additional information on the layer-by-layer growth mechanism of the films and the nature of defects at the interface with the SrRuO 3 substrate.With highly stable instrumentation, detailed information on the structure and roughness of interfaces can be provided by HAADF STEM. For example, in (Ba 0.4 Sr 0.6 )(Ti 0.5 Nb 0.5 )O 3 metallic oxide thin films deposited on MgAl 2 O 4 substrates, HAADF imaging (figure 2) provides direct evidence of lateral roughness at the level of few atomic cells. Combined with complementary focal series reconstruction of the phase contrast images, the STEM data provides detailed information necessary to understand the electronic structure changes of the first few atomic layers of these metallic oxide thin films in perfect epitaxial registry with the substrate (and less than 0.5% lattice mismatch). EELS data demonstrated the subtle changes in the Ti L 23 edges as compared to reference compounds with nominally similar Ti 3+ valence (Figure 3). These results suggest that strain can induce valence changes.Examples demonstrating the benefits of aberration-corrected low accelerating voltage microscopy in the study of carbon-based nanostructures show that it is possible to visualize single polymer chains wrapped around nanotubes (Figure 4) through the process of supramolecular functionalization [7] and other approaches [8,9].

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“…About two years later a spherical aberration corrected 200 kV TEM could be finished [2] and a Cscorrected STEM was completed [3] again one year later. The first installations of spherical aberration corrected EMs have shown new results and have proven the possibility to improve the resolution of an EM by means of an aberration corrector [4]. These developments are, however, not finished and the current state and possible future directions will be discussed.…”

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confidence: 99%

Is there a Road Map of Aberration Correction towards Ultra-High Rsolution in TEM and STEM?

Haider

Mueller

2005

MAM

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Until the mid of the nineties it was assumed aberration correction is too complicated to be ever used for routine work. However, with the emergence of aberration correctors for high-resolution electron microscopes a new generation of microscopes has been made available. This stimulating development of aberration correctors was first successful with a dedicated Low Voltage Scanning Electron Microscope for which the chromatic and the spherical aberration have been cancelled [1]. About two years later a spherical aberration corrected 200 kV TEM could be finished [2] and a Cscorrected STEM was completed [3] again one year later. The first installations of spherical aberration corrected EMs have shown new results and have proven the possibility to improve the resolution of an EM by means of an aberration corrector [4]. These developments are, however, not finished and the current state and possible future directions will be discussed.In addition to these exciting developments several groups demonstrated the reduction of the energy spread of the electron beam by means of a monochromator. This has proven to further improve the information limit of a TEM equipped with a Schottky-emitter as has been shown by [5] and recently by ZEISS [6]. Additionally, aberration corrected energy filters with increased dispersion became available for spectroscopy and spectroscopic imaging during the last years.Today, after the installation of the first generation of Cs-corrected TEMs and STEMs the question arises: What are the next developments and how will the future microscope look like? The "Road Map" splits in two trends for the future: On one side the improvement of the ultimate resolving power is always the driving parameter for future developments and on the other side the extended applicability with, for example, larger pole-pieces gaps will become at least as equally important.The availability of Cs-correctors for TEM and STEM already had a strong impact on the imaging science. For TEM bright-field imaging, for example, the imaging of light elements and, furthermore, the measurement of the occupancy of oxygen in ceramics [7] with a precision of about 10% has been demonstrated. Delocalisation effects at interfaces are no longer present and TEM dark-field imaging with atomic resolution is now possible. The improved resolving power of a Cs-corrected STEM helps to image single atoms with improved contrast [8], since the beam current at a given probe size is increased by about one order of magnitude, owing to the increased illumination cone.After having demonstrated the possibilities and advantages of spherical aberration correction in electron microscopes it was immediately clear that the achievable resolution is now set by the instrument itself. Unfortunately, the information limit of the currently existing modern instruments set by the incoherent perturbations, for example internal and external time varying fields and chromatic image blur, has not improved as dramatically as their electron-optical properties have. It turns out, th...

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A spherical-aberration-corrected 200kV transmission electron microscope

Cited by 407 publications

References 13 publications

Electron radiation damage mechanisms in 2D MoSe2

Electron radiation damage mechanisms in 2D MoSe2

Applications of Aberration-corrected TEM and STEM in Complex Oxides and Nanostructured Materials

Is there a Road Map of Aberration Correction towards Ultra-High Rsolution in TEM and STEM?

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