Detection of Single Atoms and Buried Defects in Three Dimensions by Aberration-Corrected Electron Microscope with 0.5-Å Information Limit

Abstract

The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances in aberration-correcting electron optics have led to greatly enhanced instrument performance and new techniques of electron microscopy. The development of an ultrastable electron microscope with aberration-correcting optics and a monochromated high-brightness source has significantly improved instrument resolution and contrast. In the present work, we report information transfer beyond 50 pm and show images of single gold atoms with a signal-to-noise ratio as large as 10. The instrument's new capabilities were exploited to detect a buried Sigma3 {112} grain boundary and observe the dynamic arrangements of single atoms and atom pairs with sub-angstrom resolution. These results mark an important step toward meeting the challenge of determining the three-dimensional atomic-scale structure of nanomaterials.

Background, status and future of the Transmission Electron Aberration-corrected Microscope project

“…First-order aberrations, C 1 and A 1 , are manually optimized. Adapted from Kisielowski et al (2008 spread of 0.8 eV (full width at half maximum; FWHM), the brightness of the gun exceeds 4.5 × 10 9 A cm −2 srad −1 at 300 kV. A Wien-filter-type monochromator (Tiemeijer 1999) is capable of reducing the energy spread to 0.13 and 0.08 eV at 300 and 80 kV, respectively.…”

“…The arrows on the right point out 13 two-atom columns, some of which disappear in the following image due to the influence of the electron beam. Adapted from Kisielowski et al (2008). Figure 8.…”

High-energy-resolution monochromator for aberration-corrected scanning transmission electron microscopy/electron energy-loss spectroscopy

“…A corrector of spherical aberration (C s ≡ C 3 ) for a VG Microscopes 120 kV cold field emission (CFE) scanning transmission electron microscope (STEM) produced sub-ångström resolution high-angle annular dark field (HAADF) images less than 4 years later (Batson et al 2002). The probe size was improved to 0.78 Å (at 300 kV primary voltage) soon after (Nellist et al 2004) and is now around 0.5 Å, also at 300 kV (Sawada et al 2007(Sawada et al , 2008; Kisielowski et al 2008). The currents available in atomic sized probes have also grown remarkably, to approximately 1 nA in 1.5 Å diameter probes at 100 kV (Krivanek et al 2008a) and by similar amounts at 300 kV (Watanabe et al 2006).…”

Towards production of novel catalyst powders from supported size-selected clusters by multilayer deposition and dicing

“…To test the method, an 8-sandwich sample was produced (using identical deposition conditions for each sandwich trilayer) on a TEM grid for aberration-corrected STEM analysis. This measurement technique has been successfully employed to obtain 3D information on dopants, buried defects and even single atoms using through-focal analysis [31][32][33][34]. An illustrative schematic of the through-focal method and the corresponding experimental HAADF STEM images are shown in figure 2.…”