Imaging columns of the light elements carbon, nitrogen and oxygen with sub Ångstrom resolution

Kisielowski, Christian; Hetherington, C. J. D.; Wang, Y.C.; Kilaas, R.; O’Keefe, Michael A.; Thust, A.

doi:10.1016/s0304-3991(01)00090-0

Cited by 147 publications

(93 citation statements)

References 41 publications

(44 reference statements)

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“…Further, the resolution in reconstructed exit wave images is given by the microscopes information limit, which can exceed the Scherzer point resolution by a factor of more than 2 [26]. Therefore, sub-Ångstrom resolution can be achieved [27,28] and dislocation cores in <110> oriented semiconductors can be imaged with truly atomic resolution, which was not possible before since their dumbbell spacing in <110> projection is often smaller (< 0.15 nm) than the typical 0.18 nm Scherzer point resolution of traditional phase contrast microscopes [27]. Moreover, residual lens aberration can be corrected by numerical phase plates in the exit wave reconstruction process [24].…”

Section: Instrumental Improvementsmentioning

confidence: 99%

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Sub-angstrom imaging of dislocation core structures: how well are experiments comparable with theory?

Kisielowski

Freitag²,

et al. 2006

Philosophical Magazine

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During the past 50 years Transmission Electron Microscopy (TEM) has evolved from an imaging tool to a quantitative method that approaches the ultimate goal of understanding the atomic structure of materials atom by atom in three dimensions both experimentally and theoretically. Today's TEM abilities are tested in the special case of a Ga terminated 30 degree partial dislocation in GaAs:Be where it is shown that a combination of highresolution phase contrast imaging, Scanning TEM, and local Electron Energy Loss Spectroscopy allows for a complete analysis of dislocation cores and associated stacking faults. We find that it is already possible to locate atom column positions with picometer precision in directly interpretable images of the projected crystal structure and that chemically different elements can already be identified together with their local electronic structure. In terms of theory, the experimental results can be quantitatively compared with ab initio electronic structure total energy calculations. By combining elasticity theory methods with atomic theory an equivalent crystal volume can be addressed. Therefore, it is already feasible to merge experiments and theory on a picometer length scale. While current experiments require the utilization of different, specialized instruments it is foreseeable that the rapid improvement of electron optical elements will soon generate a next generation of microscopes with the ability to image and analyze single atoms in one instrument with deep sub Ångstrom spatial resolution and an energy resolution better than 100 meV.

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Section: Instrumental Improvementsmentioning

confidence: 99%

“…If defects are imaged with sub-Ångstrom resolution they must reside in crystals that are thinner than 10 nm [27]. Consequently, only a few thousand atoms are in the proximity of the defect.…”

Section: Instrumental Improvementsmentioning

confidence: 99%

Sub-angstrom imaging of dislocation core structures: how well are experiments comparable with theory?

Kisielowski

Freitag²,

et al. 2006

Philosophical Magazine

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“…Figure 9 depicts the phase of the electron exit wave function for the disconnection r b 3 / 4 . In one part of the image, the atomic columns of oxygen and aluminum are clearly distinguished (inserted magnification) at a spacing of 85 pm [12]. In the vicinity of the disconnection, the (Fig.…”

Section: -3-disconnection Core Structurementioning

confidence: 96%

“…The sample was finally annealed under high vacuum (10 -6 Torr) in order to prevent further contamination under the electron beam in the microscope. reconstructed from a focal series of 20 lattice images recorded on a CM300 FEG/UT instrument with a 0.8 Å information limit [12]. The image simulations were performed by multislice calculations with the MacTempas and CrystalKit software packages [13].…”

Section: -Experimentalmentioning

confidence: 99%

Disconnection arrays in a rhombohedral twin in α-alumina

Lartigue-Korinek¹,

Hagège²,

Kisielowski³

et al. 2008

Philosophical Magazine

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International audienceInterfacial defects such as grain boundary dislocations are known to play an important role in the creep behavior of alumina. In the present work interfacial defects are analyzed in detail using a Volterra approach without a reference to a near-coincidence description. We investigate disconnections (boundary steps with dislocation character) in a diffusion-bonded alumina bicrystal with a misorientation close to the rhombohedral twin by conventional and atomic resolution electron microscopy. The bicrystal contains two arrays of parallel disconnections with Burgers vectors that have alternating equal and opposite twist components, so there is no long-range stress field. This configuration is discussed in terms of the stability of different grain boundary disconnection arrangements. The complex core structure of the defects is revealed by high resolution electron microscopy using exit wave reconstruction. It is shown that the defects are dissociated into two partials that delimit grain boundary segments with alternating structures

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“…For conventional TEM imaging, aberration correction is achieved with a double hexapole system and utilizes a tilt series of diffractograms, again relying on the availability of a thin amorphous film [14]. Aberration correction can also be tackled using a posteriori methods, such as exit-wave reconstruction based on through-focal image-series [7,8]. Similar resolution enhancements have been achieved using atomic-resolution electron holography [15].…”

mentioning

confidence: 99%

Progress and Perspectives for Atomic-Resolution Electron Microscopy

Smith

2005

MAM

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The atomic-resolution capabilities of the electron microscope, which first became widely accessible in the 1980s, have had a major impact across many disciplines [1]. With carefully prepared samples and correct operating conditions, assisted by quantitative image recording and processing, image characteristics can be interpreted directly in terms of individual atomic columns. With improvements in hardware and special attention to microscope environment, resolving powers close to or exceeding the one Ångstrom (0.1nm) barrier have been achieved by the latest generation of high-voltage HREMs [2][3][4]. Similar performance levels have been reached by dedicated scanning and conventional medium-voltage instruments [5,6], while sub-Ångstrom electron microscopy to resolutions of close to 0.8 nm has since been achieved using exit-wave retrieval [7,8]. Meanwhile, after a relatively dormant period during much of the 1990s, the last several years have witnessed a veritable explosion of further instrumentation hardware, including the successful implementation of aberration correctors for both conventional [9] and scanning [10] TEMs, as well as the design of electron monochromators which provide reduced energy spread and hence improved source coherence [11]. These latest developments have generated great interest and enthusiasm within the microscopy community, as well as attracting much attention from the broader materials community, especially for potential applications related to the rapidly emerging fields of nanoscience and nanotechnology.All electron lenses suffer from performance-limiting aberrations that must be removed in order to attain theoretical resolution limits. Two-fold astigmatism and third-order axial coma can be corrected manually by an experienced operator but for improved reliability and greater accuracy, online computer control or 'autotuning' of the microscope based, for example, on automated diffractogram analysis is recommended [12]. With the advent of aberration correctors, digital acquisition via slowscan CCD cameras has become indispensable. Computer analysis and control of corrector power supplies is essential for determining and then correcting most aberrations up to fourth order, including three-fold objective lens astigmatism and spherical aberration [13,14]. In the case of the probe-forming lens of the STEM, correction of the aberrations is done using multiple quadrupoleoctopole elements following analysis of a Ronchigram or shadow image obtained from a thin amorphous film [10,13]. For conventional TEM imaging, aberration correction is achieved with a double hexapole system and utilizes a tilt series of diffractograms, again relying on the availability of a thin amorphous film [14]. Aberration correction can also be tackled using a posteriori methods, such as exit-wave reconstruction based on through-focal image-series [7,8]. Similar resolution enhancements have been achieved using atomic-resolution electron holography [15]. Chromatic aberration remains as a serious obstacle to achievement of d...

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Imaging columns of the light elements carbon, nitrogen and oxygen with sub Ångstrom resolution

Cited by 147 publications

References 41 publications

Sub-angstrom imaging of dislocation core structures: how well are experiments comparable with theory?

Sub-angstrom imaging of dislocation core structures: how well are experiments comparable with theory?

Disconnection arrays in a rhombohedral twin in α-alumina

Progress and Perspectives for Atomic-Resolution Electron Microscopy

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