Noise characteristics of the gas ionization cascade used in low vacuum scanning electron microscopy

Publication Type:
Journal Article
Citation:
Journal of Applied Physics, 2009, 106 (1)
Issue Date:
2009-07-27
Filename Description Size
Thumbnail2010004245OK.pdf412.25 kB
Adobe PDF
Full metadata record
The noise characteristics of gas cascade amplified electron signals in low vacuum scanning electron microscopy (LVSEM) are described and analyzed. We derive expressions for each component contributing to the total noise culminating in a predictive, quantitative model that can be used for optimization of LVSEM operating parameters. Signal and noise behavior is characterized experimentally and used to validate the model. Under most operating conditions, the noise is dominated by the excess noise generated in the gas amplification cascade. At high gains, the excess noise increases proportionally with gain such that the signal-to-noise ratio is constant. The effects of several instrument operating parameters, including working distance, gas pressure, beam current, and detector bias, are condensed and presented in the form of a master curve. © 2009 American Institute of Physics.
Please use this identifier to cite or link to this item: