Combined STEM-EDS tomography of nanowire structures

Abstract

The 3D spatial resolution, the material contrast and the evolution of the noise are analyzed in the reconstructed volume of a combined scanning transmission electron microscopy (HAADF-STEM) and energy dispersive x-ray spectroscopy (EDS) tomography experiment. Standard simultaneous iterative reconstruction technique and HAADF-EDS bimodal tomographic reconstruction are considered for the +/−90°tomography series of a pillar shaped sample embedding a full nanowire device. With a high number of iterations, a spatial resolution for both HAADF and EDS down to 5 nanometer can be reached for this volume. Best material's contrast and minimum noise are obtained for medium number of iterations. Improvement of the signal-tonoise and contrast can be obtained by filtering the EDS data while the spatial resolution is not impacted. A fast and reliable preparation methodology for rectangularly shaped pillar samples for tomography analysis is discussed.

Applications of Transmission Electron Microscopy in Phase Engineering of Nanomaterials

“…The simultaneous 3D structural and compositional determination of multielemental nanomaterials is particularly challenging due to the complex interplay of different factors affecting image contrast. Despite the attempts to employ correlative tomography with HAADF-STEM and EDX-STEM for this purpose, the resolution achieved using this approach is typically limited to a few nanometers, primarily because of the high noise level of the X-ray signals. , Atom counting, which is based on image simulations assuming the linear relationship between EDX-STEM and ADF-STEM signals, is another potential method for achieving atomic-resolution 3D structural and compositional visualization . However, this approach is computationally intensive.…”

A Tabletop X-Ray Tomography Instrument for Nanometer-Scale Imaging: Reconstructions

“…While promising, FIB-based approaches consume the sample during the measurement, which prevents follow-up analysis with other tools. A combined Scanning Transmission Electron Microscope (STEM) and Energy-Dispersive Spectrometer (EDS) has been used recently to create material-specific 3D reconstructions of a nanowire 20 . Laboratory systems are also being developed that combine x-ray tube sources with x-ray focusing optics.…”

Spatial distribution of silica fillers in phase‐separated rubber blends investigated by three‐dimensional elemental mapping

“…The recently developed multidetector energy dispersive X‐ray spectrometry (EDX) system, in which four silicon‐drift detectors (SDDs) are placed symmetrically around the optical axis near the specimen, can solve this drawback of traditional STEM‐EDX systems. The use of a multidetector EDX system allows for the acquisition of elemental maps with equal quality and high‐detection efficiency over the entire range of tilt angles 28–30 …”