SEM: Principles

• When the electron beam hits the sample, the interaction of the beam electrons from the filament and the sample atoms generates a variety of signals.

• Depending on the sample, these can include secondary electrons (electrons from the sample itself), backscattered electrons (beam electrons from the filament that bounce off nuclei of atoms in the sample), X-rays, light, heat, and even transmitted electrons (beam electrons that pass through the sample).

Figure 17.01: Schematic of SEM set up [1].

• Figure 17.01 shows the schematic representation of the SEM. The principle elements are electron gun, condenser lens, scanning or deflection coils.

Ref.[1]. http://www.rzuser.uni-heidelberg.de/~hb6/labor/rem/index_en.html.