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Noise in secondary electron emission: the low yield case
1Institute of Scientific Instruments ASCR, Královopolská 147, 61264 Brno, Czech Republic. ludek@isibrno.cz
Journal of Electron Microscopy
|August 27, 2005
Summary
This study examines the limits of using Poisson statistics for secondary electron (SE) emission in scanning electron microscopes. Results show when non-Poisson statistics are necessary for accurate SE emission analysis.
Area of Science:
- Materials Science
- Physics
- Electron Microscopy
Background:
- Accurate assessment of scanning electron microscope (SEM) image quality and secondary electron (SE) detector efficiency relies on understanding SE emission statistics.
- Previous studies predominantly used Poisson statistics, often failing to meet its underlying prerequisites.
Purpose of the Study:
- To investigate the limitations of applying Poisson statistics to SE emission.
- To define and derive a non-Poisson factor for SE emission variance.
Main Methods:
- Statistical analysis of SE emission.
- Derivation of a non-Poisson factor formula for low-yield scenarios.
- Consideration of primary electron (PE) and backscattered electron (BSE) interactions.
Main Results:
- Identified conditions where Poisson statistics are inadequate for SE emission.
- Derived a simple formula for the non-Poisson factor in low-yield cases.
- Determined that for light elements like carbon, the non-Poisson factor is negligible at PE energies above 10 keV.
Conclusions:
- Poisson statistics have limited applicability in SEM SE emission analysis.
- A non-Poisson factor is crucial for accurate statistical modeling in many SEM applications.
- The derived formula provides a basis for more precise SE emission analysis, especially for conductive, light-element specimens.