
Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM) are advanced methods for investigating materials at the atomic and subatomic level. At Fraunhofer IMWS, all three methods are used to examine materials and components at the micro and nano level.
Transmission electron microscopy (TEM)
In TEM, an electron beam is sent through the sample, producing a detailed image of the sample's internal structure. The sample must be very thin, typically in the range of 50 to 200 nanometers, to allow the electron beam to pass through. TEM enables the investigation of the crystal structure, lattice defects, chemical composition, and bonding structure of the sample.
Scanning electron microscopy (SEM)
In SEM, an electron beam is scanned across the surface of the sample and secondary electrons are generated. These secondary electrons are detected and assembled into an image of the surface. SEM allows the surface morphology, topography, and chemical composition of the sample to be examined. Unlike TEM, SEM can also be used to examine thicker samples.
Scanning transmission electron microscopy (STEM)
STEM combines the advantages of TEM and SEM. A converged electron beam is sent through the sample and both transmitted electrons and scattered electrons are detected. This enables the simultaneous acquisition of detailed information about the internal structure of the sample (similar to TEM) and the surface (similar to SEM). STEM enables the chemical composition, crystal structure, and morphology of the sample to be examined at a high level of resolution. These advanced microscopy techniques play an important role in materials science, nanotechnology, biology, semiconductor research, and many other areas of science and technology.