Ion induced secondary electron imaging is a technique used to capture the surface information of a solid sample. The process involves beaming ions to a sample which cause an ejection of electrons and materialfrom the sample. The electrons are ejected from the sample due to two driving forces of the ions, potential electron emission (PEE) and kinetic electron emission (KEE). PEE is caused by the potential energy characteristic of the type of ion that is beamed; ion charge would be considered potential energy. PEE is similar to the potential energy that objects have when raised off the ground. KEE is characterized by the speed, kinetic energy, at which the ions strike the sample.
Both of these energies cause electrons to eject from the sample; these electrons are called secondary electrons. Alongside the secondary electrons, the ions also cause sample material to be ejected. This material is the cause of what is called sputtering and is neutral or positively charged. The secondary electrons and the sputtered material are analyzed to produce images of the sample. The images produced can have a resolution up to 5 nanometers and reveal chemical differences, morphology, and topography of the sample.
Undergraduate Senior Student
Department of Chemical Engineering, Virginia Tech