Showing papers by "Ondrej L. Krivanek published in 2003"
TL;DR: A quadrupole/Octupole/octupole corrector of a new design is described, which will correct all fifth-order aberrations while introducing less than 0.2mm of additional C(c), which promises to lead to routine sub-A electron probes at 100kV, and to sub-0.5A probes at higher operating voltages.
165 citations
TL;DR: In this article, the sub-Angstrom probe of an aberration-corrected scanning transmission electron microscope was used to enable imaging and analysis of nanostructures and interfaces with unprecedented resolution and sensitivity.
Abstract: The sub-Angstrom probe of an aberration-corrected scanning transmission electron microscope will enable imaging and analysis of nanostructures and interfaces with unprecedented resolution and sensitivity. In conjunction with first-principles theory, new insights are anticipated into the atomistic processes of growth and the subtle link between structure and functionality. We present initial results from the aberration-corrected microscopes at Oak Ridge National Laboratory that indicate the kinds of studies that will become feasible in the near future. Examples include (1) the three-dimensional location and identification of individual dopant and impurity atoms in semiconductor interfaces, and their effect on local electronic structure; (2) the accurate reconstruction of surface atomic and electronic structure on nanocrystals, and the effect on optical properties; and (3) the ability to distinguish which configurations of catalyst atoms are active, and why.
20 citations
TL;DR: In this paper, an aberration correction on the VG Microscopes' HB603U STEM at Oak Ridge National Laboratory has brought immediate benefits through improved resolution, image contrast and signal to noise ratio.
Abstract: Installation of an aberration-corrector on the VG Microscopes’ HB603U STEM at Oak Ridge National Laboratory has brought immediate benefits through improved resolution, image contrast and signal to noise ratio [1]. Figure 1 shows the improvement predicted theoretically after correction of third order aberrations from an aberration limited 1.26Å probe to a 0.5 Å probe. The experimental Ronchigram indeed shows the anticipated expansion of the region of flat phase by a factor of ~ 2.5, but the image resolution is still limited by probe instabilities. Improved contrast is seen in the line trace of SiÆ110æ, and Fig. 2 shows contrast decreasing smoothly to 0.84 Å in the power spectrum of Æ1 1 00 æ SiC. Weak spurious spots are also present due to the probe instabilities, and it is hoped these will be cured in the near future.
9 citations
TL;DR: In this article, an atomic-resolution EELS elemental map was produced by using the inner-shell loss inelastic scattering, probed by electron energy-loss spectroscopy (EELS).
Abstract: Aberration correctors for scanning transmission electron microscopes (STEMs) now readily produce sub-Å resolution high-angle annular dark field (HAADF) images [1, 2]. They also make possible substantially increased currents in atom-sized probes. The improvement in the probe current brings forth the day when signals with cross-sections smaller than high-angle elastic scattering will be able to routinely produce atomic-resolution information. The foremost among such signals is inner-shell loss inelastic scattering, probed by electron energy-loss spectroscopy (EELS). This paper briefly reviews our efforts towards the production of atomic-resolution EELS elemental maps.
1 citations