Impact ionization

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In impact ionization , an atom or molecule is ionized or an additional pair of charge carriers is generated in a semiconductor. The collision partner is typically an electron or ion accelerated in an external electric field . High-energy electromagnetic radiation or, if the temperature is high enough, an electron, ion or neutral atom can also lead to impact ionization as a result of their disordered temperature movement. In semiconductors, holes can also cause impact ionization. Subsequent recombination can result in luminous phenomena in the visible area.

Impact ionization can lead to a chain reaction , also known as the avalanche effect in semiconductors , if the released charge carriers, before they recombine, cause more than one further ionization process on average. This current-boosting effect can be desirable ( counter tube , gas discharge lamp ) or undesirable ( lightning strike , NEMP ).


Individual evidence

  1. ^ Wolfgang Karl Ernst Finkelnburg: Introduction to Atomic Physics . Springer-Verlag, 2013, ISBN 978-3-662-28827-6 , pp. 20 ( limited preview in Google Book search).