Development of a Practicable Digital Pulse Read-Out for Dark-Field STEM.

Area of Science:

• Materials Science
• Electron Microscopy
• Nanotechnology

Background:

• Low-dose techniques are crucial for imaging beam-sensitive materials in scanning transmission electron microscopy (STEM).
• Conventional methods using reduced beam current or faster rastering lead to artifacts like signal-streaking and poor signal-to-noise ratios (SNRs).

Purpose of the Study:

• To present an alternative digital approach for capturing annular dark-field (ADF) STEM images.
• To demonstrate the elimination of analog artifacts and achieve high-SNR images at low electron doses.

Main Methods:

• Utilizing pulse-counting of individual electrons scattered to the ADF detector.
• Implementing digital image formation immune to analog detector artifacts.
• Comparing digital results with conventional analog recordings on ThermoFisher Titan G2 and Nion UltraSTEM200 instruments.

Main Results:

• Digital pulse-counting produces images free from streaking and afterglow artifacts.
• High-SNR images are achievable even with low beam currents.
• Demonstrated effectiveness on both 300 kV and 200 kV STEM instruments.

Conclusions:

• Digital electron counting offers a superior method for low-dose STEM imaging of sensitive materials.
• This technique significantly enhances image quality and reliability in electron microscopy.
• The method provides a robust solution for preserving sample integrity during characterization.