About the information depth of backscattered electron imaging.

Area of Science:

• Materials Science
• Electron Microscopy
• Surface Analysis

Background:

• Understanding the information depth of backscattered electrons (BSE) is crucial for accurate interpretation of scanning electron microscopy (SEM) images.
• Existing methods for estimating BSE information depth often rely on theoretical models or simulations, with limited direct experimental validation.

Purpose of the Study:

• To directly measure the information depth of BSE imaging in SEM.
• To compare experimental results with existing theoretical equations and Monte Carlo simulations.
• To provide recommendations for routine estimation of BSE information depths.

Main Methods:

• Direct measurement of BSE information depth using a steel sample with buried precipitates.
• Comparison of planar view SEM-BSE images with cross-sectional images obtained via Focused Ion Beam (FIB) milling.
• Determination of information depth across a range of electron energies (keV).

Main Results:

• Experimental BSE information depths were determined and compared against two published equations.
• Results were also compared with simulations performed using widely available Monte Carlo software.
• Discrepancies between experimental data and theoretical/simulated values were observed, highlighting the need for direct measurement.

Conclusions:

• Direct experimental measurement provides a more reliable method for determining BSE information depth.
• The study offers practical recommendations for routine BSE information depth estimations in SEM.
• Accurate information depth determination is essential for quantitative analysis and materials characterization using SEM-BSE imaging.