Scanning electron microscopy

The scanning electron microscope (SEM) is an extremely versatile tool for the study of surfaces and fine structures. Where the light microscope is reaching the limits of resolution, that's where the use of the SEM starts. At ALPS different SEMs are available. A PHENOM XL for fast and routine operation, and a Zeiss High Resolution SEM. The HR instrument equipped with Schottky emitter allows magnifications up to 1'000'000 times with a resolution of 1.5 to 3 nm. The sample to be investigated is scanned under vacuum using an electron beam. At the same time an image of the prepared surface is recorded. Additional information about the material structure (material contrast) and composition (X-ray microanalysis, EDS) can be obtained as well.

SEM operates under vacuum or slightly elevated pressures of  3 Pa to 133Pa. These elevated pressure is useful to avoid the development of surface charges on non-conducting materials.  This enables us to analyze non or very poorly conductive samples without coating at highest image possible image quality.

Applications of SEM in Images

#1/ Dentist tool

#2 / wood section / spruce

#3 / Multi ceramics

#4 / various examples

#5 / Gewaltbruch

#6 / Molybdenon oxyd

#7 / Molybdenon oxyd zoom

#8 / mould

#9 / mould

typical application of SEM:

  • fracture surface analysis in cases of damage
  • investigation of surfaces and surface defects as well as
  • traces of wear examination of small objects (for example particles, powders, microstructures)
  • topography measurements (3-D representations, roughness studies)
  • analysis of contamination, corrosion products, coatings, inclusions
  • structural analysis of very fine-grained materials (ceramics, hard metals)
  • failure analysis of electronic components (whisker formation, cracking)

In the scanning electron microscope the X-rays emitted by a sample can be detected. For objects of about 2µm lateral extent and 10 microns thickness the elemental composition can be determined from the X-ray spectrum. The spectrum can also be evaluated quantitatively. However the presence of light elements (C, O, N) with expected low levels (<1%) one has to expect a large measurement error.

 Introduction to electron microscopy



GD-OES a complementary method