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Effects of Electron-ion Recombination on Contrast in ESEM Images

Published online by Cambridge University Press:  02 July 2020

M. Toth
Affiliation:
Polymers and Colloids Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 OHE, U.K
B. L. Thiel
Affiliation:
Polymers and Colloids Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 OHE, U.K
A. M. Donald
Affiliation:
Polymers and Colloids Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 OHE, U.K
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Abstract

We present experimental evidence for the effects of electron-ion recombination on contrast formation in secondary electron (SE) images obtained using an environmental scanning electron microscope (ESEM). Inclusion of the effects of SE-ion recombination in the theory of ESEM image formation accounts for contrast reversal observed, under appropriate conditions, in SE images of conductors (ie, in the absence of localized specimen charging) and of insulators that exhibit localized charging. Previously unexplained dynamic contrast caused by temporal charging can be understood if both conventional models of the effects of charging on SE emission, and the proposed role of SEion recombination in ESEM image formation are accounted for.

In an ESEM, the extent of charging exhibited by insulating specimens can be controlled by varying the type and pressure (P) of the imaging gas, and operating parameters that determine the extent to which the gas is ionized (eg, detector bias, VGSED, and working distance, WD).

Type
Technologists’ Forum: ESEM/Lv/Vp: Imaging at Low Vacuum (Organized by J. Killius)
Copyright
Copyright © Microscopy Society of America 2001

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References

References:

1.)Goldstein, J.I. et al, Scanning electron microscopy and x-ray microanalysis, Plenum Press, 1992.CrossRefGoogle Scholar
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3.)Toth, M. et al, Appl. Phys. Lett. 77(9), 13421344, 2000CrossRefGoogle Scholar