Transmission Electron Microscopy (TEM)

This TEM micrograph shows the same interface as above, captured at 410kx magnification. At this level of magnification, it is possible to see individual columns of atoms in within the crystalline domains of the materials.

Transmission electron microscopy (TEM) is the highest-resolution imaging technique available today. It is used to visualize sample features with atomic-level spatial resolution limits to characterize the morphology of complex nanostructures.

“These are incredible images. Thanks for the preview.
It is so satisfying to get definitive answers to our questions!”
– Brad Aitchison, Sr. Process Engineer, Redlen Technologies

Strengths

Highest possible spatial resolution: limit is atomic-scale
Bright Field and Dark Field imaging
Distinct imaging modes allow isolation of certain types of contrast information
Compatible with chemical (EDS) analysis and electrochemical analysis (EELS) techniques
Tomography and 3D reconstruction

Limitations

Requires extensive sample prep (normally performed with a FIB-SEM)
Specimens can be damaged if low dose techniques are not employed
Minimal topographical sensitivity
Typically only able to image a very small portion of the sample

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Example Outputs Instruments Used How TEM Works

Sample Requirements

Samples must be very thin (electron transmissive): < 100 nm thick
- Covalent provides sample preparation for TEM analysis
Specialized lamella prepared and mounted on TEM sample holder

TEM Example Outputs

Ultra high resolution brightfield TEM image captured with the 4k Gatan OneView camera.

HAADF (High-Angle Annular Dark Field) STEM image of a MiM (Metal – Insulator – Metal) capacitor structure within an integrated circuit.

TEM micrograph capturing the interface between two layers of distinct materials with various crystalline phases. This image was shot at low mag (35kx magnification).

This TEM micrograph shows the same interface as above, captured at 410kx magnification. At this level of magnification, it is possible to see individual columns of atoms in within the crystalline domains of the materials.

TEM Instruments Used

JEOL JEM-F200 Microscope

Cold-Field-Emission Gun (CFEG) Electron Source
- Accelerating Voltage: 80 kV or 200 kV
- High current and beam stability = ultra-high spatial resolution
- TEM Point Resolution: 0.19 nm
- STEM-HAADF Resolution: 0.14 nm
High Energy Resolution: 0.3 eV
High-res Electron Energy Loss Spectroscopy (EELS)
- Fine Structure/Oxidation State Determination
- Plasmon Resonance Analysis (CFEG supports zero-loss peak)
Gatan GIF Continuum ER Image Filter for Energy Filtered TEM (EFTEM) for light-element materials
Dual SDD Energy Dispersive X-ray Spectroscopy (EDX/EDS) detectors

View Instrument Brochure

ThermoFisher Scientific Talos F200X (S)TEM

TEM Line Resolution: ≤ 0.10 nm
TEM Information Limit: ≤ 0.12 nm
Maximum Alpha Tilt: ± 90°
(with tomography holder)
Maximum Diffraction Angle: 24°
Electron Source: High-Brightness Field Emission Gun
Gatan OneView CCD: 16MP 4K camera
Quad-EDS Detectors for enhanced sensitivity and detection limits

View Instrument Brochure

In a TEM, a high-energy electron beam is applied to a very-thin sample (a lamella), which is prepared to be electron-transmissive i.e. typically 20 to 50 nm thick.

As the beam passes through the sample, scattering interactions occur between its electrons and the atoms present which alter the transmitted beam intensity. These scattering events can produce several types of contrast in the final image, including: amplitude contrast (arising from atomic number and mass/thickness) phase contrast (from quantum phase shifting due to multiple scattered beams’ interference), diffraction contrast (from crystal structure and orientation), and more.

Different imaging modes on the TEM can target certain types of contrast over others, facilitating specialized analysis of relevant information.

The electron beams transmitted through the sample are focused by the TEM objective lens to form an image below it. This image is then magnified through a final series of electromagnetic optics, and detected by a specialized CCD camera.

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