infocus #14 June 2009 SEM: Understanding & Optimising Scanning Electron Microscopy Performance

Steve Chapman explains the importance of understanding the basics of Scanning Electron Microscopy to get the best and most reliable data from your SEM.

DOI: 10.22443/rms.inf.1.45

Whilst the scanning electron microscope with the help of modern computing and sophisticated imaging systems has developed into an instrument capable of imaging almost any structure, the techniques used by operators have not always progressed at the same rate. Sophisticated computers and the user friendly interfaces may appear to simplify operation, but a basic understanding of the beam-specimen reaction is frequently ignored, possibly spoiling the information content of the image. For example the selection of accelerating voltage is extremely critical, it determines the level of penetration and the signal balance between the surface and the sub surface. The signal contributions that most satisfy the operator’s demands will also be related to the working distance selected; this will vary the mix of signals changing the information displayed.

Microscopists are scientists, who are defined as being people who experiment; therefore we should experiment with the parameters within the SEM. Once the instrument is optimised, adjustments to display the data with appropriate grey levels will further maximise the information.

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Author

Steve Chapman

Electron Microscopy Consultant

Steve Chapman formed Protrain in 1982 offering consultancy in electron microscopy worldwide. Steve first became involved with electron microscopes in 1964 at the Department of Physical Metallurgy, University of Birmingham, England. Moving on to working as an electron microscope service engineer in the UK his service activities as a senior engineer eventually took him throughout Europe. He then moved into instrument sales and marketing where he worked with a number of electron microscope and accessory manufacturers in the demonstration and application fields. Steve has been involved with the design of cryo systems and sputter coaters for scanning electron microscopy, as well as the design of transmission and scanning electron microscopes themselves. Steve runs his “in house” courses and consultancy in individual laboratories in many parts of the world, north and south of the equator. He also is the senior lecturer in a number of residential short courses in universities across Australia and South Africa. Steve also runs courses to train electron microscope service technicians across the range of manufacturers.