Electron Microscopy Nest:

The Electron Microscopy Nest is a platform designed for sharing fundamental knowledge of Electron Microscopy, along with the latest advancements in Electron Microscopy Analysis and Characterization Technology within the field.

Electron Microscopy in Materials Science and Engineering

Scanning Electron Microscopy

In basic scanning electron microscopy (SEM), a beam of highly energetic (0.1-50 keV) electrons is focused on a sample surface. This can produce several interactions including the emission of secondary electrons, backscattered electrons, photons, and X-rays; excitation of phonons; and diffraction under specific conditions.

Because the bombarding electron beam is scanned in the X-Y plane, an image for each of these different processes can be mapped with a suitable detector. A detector for secondary electrons, standard to all basic SEMs, records topography of the surface under observation with resolution on the order of 1-2 nm and magnification range from 10x to 500,000x. In addition, information on composition, phase, electrical, optical, thermal, and other properties can be mapped with excellent resolution with appropriate detectors. The basic SEM is probably the most versatile instrument in materials science. Beyond being an isolated instrument, it also represents a platform. When combined with other accessories, the electron microscope can be used to further control manipulation of nanostructures or select an area for observation with high precision. In situ phase transitions can be seen when cryogenic or heating stages are installed in the chamber. The combination with a focused ion beam is used for other applications such as sample preparation for transmission electron microscopy.

Focused-Ion-Beam

The Focused-Ion-Beam (FIB) workstation integrates a dual-beam setup comprising a FIB column and a scanning electron microscope (SEM) column on a single platform. Its functionalities encompass ion milling, metal deposition, ion and electron imaging at both micro and nanoscale levels, particularly applied to advanced photovoltaic materials and devices.

Furthermore, the dual-beam FIB facilitates the integration of other analytical tools such as Transmission Electron Microscopy (TEM) and enables precise, site-specific sample preparation for TEM, SEM, and complementary sample evaluations.

The FIB system also features capabilities for acquiring chemical spectra and elemental maps through energy-dispersive spectroscopy (EDS). Additionally, it enables the generation of three-dimensional chemical reconstructions by combining controlled ion milling with chemical mapping. The system is equipped with a gas injection system (GIS) for platinum metal deposition, which can be employed in conjunction with either ion-beam-assisted or electron-beam-assisted chemical vapor deposition techniques.

Moreover, utilizing a digital patterning generator enables the complete FIB milling or deposition of intricate structures, with parameters supplied by software or directly input via bitmap files.

Transmission/Scanning Transmission Electron Microscopy

Transmission/Scanning Transmission Electron Microscopy (TEM/STEM) involves the bombardment of a thin sample, typically less than 200 nm thick, by a tightly focused beam of single-energy electrons. These electrons possess sufficient energy to pass through the sample, and the resulting transmitted or scattered electron signal is significantly amplified by a sequence of electromagnetic lenses. This amplified signal can be observed through electron diffraction, amplitude-contrast imaging such as diffraction contrast, or phase-contrast imaging such as high-resolution TEM.

Transmission electron diffraction patterns aid in determining the crystallographic structure of a material, while amplitude-contrast images provide insights into the material's chemistry, microstructure, and defects. Phase-contrast imaging or high-resolution (HR) TEM imaging offers detailed information about the material's microstructure and defects at an atomic scale.

In scanning transmission electron microscopy (STEM), a highly focused electron probe scans across the material, collecting various types of scattering data as a function of position. Transmitted electrons at high scattering angles can be gathered to generate high-resolution, chemically sensitive images with atomic number (Z-) contrast. Additionally, the x-rays generated can be captured using an energy-dispersive X-ray spectroscopy (EDS) detector to create high spatial resolution compositional maps. Electron energy losses can also be detected using a Gatan image filter (GIF) to map the compositional and electronic properties of materials.

Applications

Crystallography

Electron diffraction is used to determine the crystallographic structure of materials on a fine scale.

Microstructure

Diffraction-contrast and high-resolution TEM yields information on the composition, microstructure, and atomic structure of materials and defects. High-resolution STEM Z-contrast imaging provides directly interpretable, chemically sensitive images of the structure of materials, defects, and interfaces in samples with atomic resolution.

Composition

EDS and EELS provide quantitative and qualitative compositional analysis of materials to sub-nm spatial resolution for almost any element. STEM EDS and EELS enable elemental mapping with nm-scale resolution. EELS also provides information on the electronic properties of materials. A GIF enables elemental mapping by energy-filtered TEM with high-spatial resolution.

Cross-sectional Analysis

Investigates the structure, composition, and perfection of multilayer films and interfaces.

The following table is a condensed listing of equipment, techniques, applications, and properties of instrumentation for Transmission/Scanning Transmission Electron Microscopy.