There are two types of electron microscopes that are commonly used. They are transmission electron microscopy (TEM) and scanning electron microscopy (SEM).
TEM was first developed by Ernst Ruska and Max Knoll. They were two researchers from Germany in 1932. At that time, Ernst Ruska was a doctoral student and Max Knoll was his adviser. Because the findings were surprising in the world, Ernst Ruska was awarded the Nobel Prize in Physics in 1986.
As the name implied, TEM worked with the principle of firing electrons into a thin layer samples, then further information about the composition structure of the sample could be detected from the analysis of the nature of the collision, the reflection and the phase of electron beam that penetrated the thin layer. From the reflectance characteristic of the electron beam, you could also know the crystal structure and its direction.
Even, from a more detailed analysis, you could read row of atomic structure and absence of defects on the structure. Just kept in mind, for this TEM observation, the sample should be diluted, so that the thickness was thinner than 100 nanometers. And, this was not an easy job. In this case, you needed special expertise and equipment.
The objects that could not be thinned would be processed by the TEM difficultly. In the manufacture of electronic devices, TEM was often used to observe the cross section/ slice devices and the characteristics of crystal in these devices. In other cases, TEM was also used to observe the slice of surface of the device.
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