Scanning Transmission Electron Microscopy (STEM)

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

Scanning transmission electron microscopy (STEM) is a hybrid electron microscopy technique used for imaging and morphological characterization with atomic-scale resolution.

STEM is available on both Covalent’s FIB-SEM  instruments, as well as our TEM. All Covalent (S)TEM systems have fully integrated energy-dispersive x-ray spectrometers (EDS or EDX) for correlative elemental composition and mapping analysis.

Strengths

  • Atomic-level resolution limit – substantially improved over conventional SEM
  • Enables spatial correlation of advanced TEM signals:
    • Energy-dispersive X-ray Spectroscopy (EDS / EDX): elemental composition and mapping
    • Electron Energy Loss Spectroscopy (EELS): bonding state and light element analysis with some electrochemical insights
    • High-Angle Annular BF, and DF scattered beams (HAABF / HAADF): standard ultra-high-resolution imaging with additional atomic-number contrast for mapping applications
    • Kikuchi Bands: crystallographic analysis for electron diffraction patterns

Limitations

  • Requires extensive sample preparation to generate a thin-enough analytical window for the material to be electron-transmissive
  • High-energy, the highly-focused electron beam can cause sample damage

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Scanning Transmission Electron Microscopy Services

Scanning Transmission Electron Microscopy

Scanning transmission electron microscopy (STEM) is a hybrid electron microscopy technique used for imaging and morphological characterization with atomic-scale resolution.

STEM is available on both Covalent’s FIB-SEM  instruments, as well as our TEM. All Covalent (S)TEM systems have fully integrated energy-dispersive x-ray spectrometers (EDS or EDX) for correlative elemental composition and mapping analysis.

Sample Requirements

Example Outputs

High angle annular dark-field (HAADF) TEM image captured at an ROI for joint analysis with EDS.

Energy dispersive spectroscopy (EDS) map of element distribution across the interface imaged above. This image is a composite overlay of the measured signal intensities of 9 different elements.

Instruments Used

 JEOL JEM-F200 Microscope

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

ThermoFisher Scientific Talos F200X

  • STEM Resolution Limit: 0.16 nm
    (in High-Angle Annular Dark Field – HAADF – mode)
  • STEM Detectors:
    • HAADF
    • On-Axis Bright Field
    • On-Axis Dark Field
  • Maximum Alpha Tilt: ± 90°
    (with tomography holder)
  • Maximum Diffraction Angle: 24°
  • Electron Source: High-Brightness Field Emission Gun
View Instrument Brochure
ThermoFisher Scientific Helios 5 UC (x3)

ThermoFisher Scientific Helios 5 UC (x3)

  • Maximum Horizontal Field Width: 2.3 mm at 4 mm WD
  • Electron Beam:
    • Resolution Limit: 0.7 nm at 1 kV
    • Current Range: 0.8 pA to 100 nA
    • Accelerating Voltage Range: 350 V to 30 kV
  • Ion Beam:
  • Electron Beam:
    • Resolution Limit: 4.0 nm at 30 kV using preferred statistical method
    • Current Range: 1 pA to 100 nA
    • Accelerating Voltage Range: 500 V to 30kV
View Instrument Brochure
ThermoFisher Scientific  Scios

ThermoFisher Scientific Scios

Optimized to achieve best performance across a wide array of sample types.

  • Powerful charge neutralization
  • Enables analysis on magnetic samples
  • Able to operate above vacuum pressure

How STEM Works

Like SEM systems, STEM instruments use a narrow, focused electron beam spot to probe the sample, scanning it in a raster pattern over an analytical area of interest. The output image is produced by detecting the scattered signal intensity at each pixel as the beam scans.

In a STEM – as in a TEM – the detector is mounted underneath the sample and picks up electrons which are transmitted through it. As such, STEM can only be used when the sample is sufficiently thin to be electron-transmissive.

In Covalent’s (S)TEM-enabled instruments, STEM offers improved spatial resolution compared to an SEM, and improved spatial correlation (for element mapping) compared to normal TEM.