Sample Surface Charge Elimination

  • Patrick Echlin

11.1 Introduction

More than 60 years ago, Knoll (1941) discovered that a piece of mica examined in an early predecessors of the commercial scanning electron microscopes, appeared bright while the surrounding regions appeared dark. This phenomenon was referred to as charging and is a common feature of most secondary electron images of non-conducting specimens. This is because the secondary electrons are emitted with such low energies, 5–50 eV, that local potentials due to charging can have a large effect on the collection of the SE signal detector, which typically has a potential of +300 V. Table 11.1 shows the wide range of electrical resistivity of the six general types of specimens studied in the SEM together with some of the materials used as conductive coating layers.
Table 11.1

Electrical resistivity of samples from each of the six different categories of specimens considered in this book. Resistivity expressed as Ω.cm at 300K



Hard dry inorganic





Coating Layer Target Material High Purity Argon Incident Beam Energy Disposable Glove 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Cambridge Analytical MicroscopyUK

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