TEM illumination settings study for optimum spatial resolution and indexing reliability in crystal orientation...

Area of Science:

• Materials Science
• Physics
• Electron Microscopy

Background:

• Automated orientation and phase mapping tools are crucial for analyzing materials at the nanoscale.
• Transmission Electron Microscope (TEM) illumination settings significantly impact spatial resolution and data quality.

Purpose of the Study:

• To analyze the impact of different TEM illumination settings on spatial resolution and indexing quality.
• To compare microprobe and nanoprobe modes in terms of electron probe size, convergence angle, and mapping accuracy.

Main Methods:

• Utilized a FEI Tecnai F20 (S)TEM with a 10μm C2 aperture.
• Investigated two TEM configuration modes: microprobe (parallel illumination) and nanoprobe (convergent beam).
• Evaluated spatial resolution and the fraction of mis-indexed points for each mode.

Main Results:

• Nanoprobe mode achieved higher spatial resolution (~1nm) compared to microprobe mode (3nm).
• Nanoprobe mode resulted in a higher fraction of mis-indexed points (15%) versus microprobe mode (1%).
• Indexing errors in nanoprobe mode correlate with a threefold increase in convergence angle.

Conclusions:

• Spatial resolution in TEM mapping is intrinsically linked to indexing quality.
• The convergence angle is a critical parameter affecting the accuracy of automated orientation and phase mapping.
• Optimizing TEM settings requires careful consideration of the trade-off between spatial resolution and indexing accuracy.