Scanning Electron Microscopy

Scanning Electron Microscopy is an excellent method for providing high spatial resolution images on a wide range of samples.  SEM provides high depth of focus images of 3 dimensional structures as well as compositional contrast images.  X-ray microanalysis to determine the actual composition of samples, and other spectroscopies are also possible if the instrument is fitted with additional hardware.

How it works – the sample is imaged with a finely focused electron beam that is scanned across the sample.  Various signals are generated as a result of the interaction of the electron beam with the sample.  These signals are collected with an appropriate detector. The most common signal used in an SEM is that from secondary electrons which display the sample morphology.

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Instrumentation Available

Key Attributes

  • Resolution 1nm
  • Accelerating voltage range 0.1 – 30kV
  • Typical Signals
    • Secondary Electrons
    • Back-scattered Electrons
    • Characteristic X-rays
    • Light
    • Absorbed Electrons
    • Transmitted Electrons


  • Straightforward sample preparation (samples generally must be vacuum compatible)
  • Large depth of focus
  • Nanometer scale spatial resolution
  • Can work with large samples (several
  • Signals can be mixed to form a composite image
  • Signals can provide information from the surface, or from the bulk a few microns deep.
  • Additional imaging and analysis capabilities easily added
    • X-ray microanalysis
    • Electron back-scattered diffraction
    • Electron beam lithography


  • Samples need to be vacuum compatible
  • Potential for beam damage of soft materials
  • More difficult to analyze insulating samples


  • High resolution imaging of a wide variety of properly prepared samples
  • Compositional analysis of samples
  • Feature size measurement
  • Electron beam lithography
  • Electron backscattered diffraction – crystallographic orientation mapping

Additional Reading