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Microcalorimeter Energy Dispersive Spectrometry for Low Voltage SEM

Published online by Cambridge University Press:  02 July 2020

D. A. Wollman
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
Dale E. Newbury
Affiliation:
National Institute of Standards and Technology, Gaithersburg, MD20899
G. C. Hilton
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
K. D. Irwin
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
D. A. Rudman
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
L. L. Dulcie
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
N. F. Bergren
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
John M. Martinis
Affiliation:
National Institute of Standards and Technology, Boulder, CO80303
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Extract

Microanalysis performed at low electron beam energies (≤ 5 keV) is limited by the physics of x-ray generation and the performance of existing semiconductor energy dispersive spectrometry (EDS) and wavelength dispersive spectrometry (WDS). Low beam energy restricts the atomic shells that can be excited for elements of intermediate and high atomic number, forcing the analyst to consider using unconventional M- and N-shells for elements such as Sn and Au. Unfortunately, these shells have very low fluorescent yield, which results in inherently low spectral peak-to-background ratios. The modest energy resolution of semiconductor EDS leads to poor limits of detection for these weakly emitted photons. The situation is further complicated by the inevitable interferences with the much more strongly excited K-shell x-rays of the light elements, particularly carbon and oxygen. WDS has the spectral resolution to overcome the resolution limitations of semiconductor EDS. However, WDS has a low geometric efficiency, and because of its narrow instantaneous spectral transmission, spectral scanning is required to detect and analyze x-ray peaks. Moreover, the high resolution field-emission-gun scanning electron microscope (FEG-SEM) provides only a few nanoamperes of beam current.

Type
Low Voltage (1-5 kv) X-ray Microanalysis
Copyright
Copyright © Microscopy Society of America

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References

references

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