Diffraction contrast dependence on sample thickness and incident energy in on-axis Transmission Kikuchi Diffraction...

Area of Science:

• Materials Science
• Crystallography
• Electron Microscopy

Background:

• Automated orientation mapping in Scanning Electron Microscopy (SEM) traditionally relies on Electron Backscatter Diffraction (EBSD).
• The Transmission Kikuchi Diffraction (TKD) technique offers an alternative with improved spatial resolution.
• Previous TKD configurations utilized an
• off-axis
• detector setup.

Purpose of the Study:

• Introduce and evaluate a novel, TEM-like
• on-axis
• detector geometry for TKD.
• Investigate the diffraction contrast variations produced by this new configuration.
• Provide guidance for experimentalists to optimize TKD imaging parameters.

Main Methods:

• Implementation of a new
• on-axis
• detector configuration in SEM for TKD.
• Systematic variation of sample thickness, incident electron energy, atomic number, and scattering angle.
• Analysis of observed diffraction contrast features (spots, lines, bands).

Main Results:

• The
• on-axis
• TKD geometry generates a wide spectrum of diffraction contrasts.
• Diffraction contrast is sensitive to sample thickness, incident energy, atomic number, and scattering angle.
• A model based on plasmon and phonon scattering explains the disappearance of diffraction spots with increasing thickness and energy.

Conclusions:

• The new
• on-axis
• TKD configuration offers enhanced control over diffraction contrast.
• Understanding contrast mechanisms aids in selecting optimal microscope and sample parameters for orientation mapping.
• The study reviews the strengths and weaknesses of different diffraction features for orientation mapping applications.