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Time Dependent Study of the Positive ion Current in the Environmental Scanning Electron Microscope (ESEM)

Published online by Cambridge University Press:  02 July 2020

S.W. Morgan  and
M.R. Phillips
S.W. Morgan
Affiliation:
Microstructural Analysis Unit, University of Technology, Sydney, PO Box 123, Broadway, New South Wales, Australia2007
M.R. Phillips
Affiliation:
Microstructural Analysis Unit, University of Technology, Sydney, PO Box 123, Broadway, New South Wales, Australia2007
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Abstract

The Environmental Scanning Electron Microscope (ESEM) is capable of image generation in a gaseous environment at sample chamber pressures of up to 20 torr. in an ESEM, low energy secondary electrons emitted from a sample surface, by virtue of the primary electron beam, are accelerated towards the positively biased metallic ring (typically +30 to +550V) Gaseous Secondary Electron Detector (GSED). As these electrons accelerate towards the ring they undergo ionizing collisions with gas molecules producing positive ions and additional electrons known as environmental secondary electrons. The environmental electrons further ionize the gas on their way to the ring producing a cascade amplification of the original signal. The amplified signal induced in the ring is used to form an image. The electric field generated between the GSED ring and the grounded stage causes the positive ions produced in the cascade to drift towards the sample, effectively neutralizing negative charge build up on the surface of a non-conducting sample.

Type
Technologists’ Forum: ESEM/Lv/Vp: Imaging at Low Vacuum (Organized by J. Killius)
Information
Microscopy and Microanalysis , Volume 7 , Issue S2: Proceedings: Microscopy & Microanalysis 2001, Microscopy Society of America 59th Annual Meeting, Microbeam Analysis Society 35th Annual Meeting, Long Beach, California August 5-9, 2001 , August 2001 , pp. 788 - 789
Copyright
Copyright © Microscopy Society of America 2001

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