Practical Electron Microscopy and Database

An Online Book, Second Edition by Dr. Yougui Liao (2006)

Practical Electron Microscopy and Database - An Online Book

Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

Emission Depth of Secondary Electrons

The emission depth of secondary electrons (SEs)  is different from materials to materials, depending on escape depth of SEs. The emission depths for metals and insulators are 5 nm and 50 nm, respectively.

Constant-loss approximation [1 – 3] suggested that the energy dissipation of primary electrons (PE) within the material is approximately constant, the number of primary electrons would decrease linearly to a depth R. The number of SEs produced per unit path length would be a constant, given by,

           Constant-Loss Approximation on Process of Secondary Electron Generation ----------------- [4800]

where ξ -- Energy required to excite one SE inside the solid
R -- Maximum range of the PE.

 

 

 

 

[1] Joy DC (1987) J Microsc 147(1):51
[2] Dionne GF (1973) J Appl Phys 44(12):5361
[3] Lye RG, Dekker AJ (1957) Phys Rev 107(4):977