IGBT Modules - Technologies, Driver and Application (Second Edition) - page 24

The impurity is introduced by doping, for example. SRH recombination has a
greater level of probability than band-to-band recombination, as the direct
transition is not via the total bandgap but exclusively via band levels, so that
less energy is required for each transition. SRH recombinations are frequently
seen in lowdoped zones of semiconductors.
Auger recombination
. In Auger recombination, this is achieved by a
transition of the charge carrier going directly from the conduction band to the
valence band. However, in this case the energy of the charge carrier is not
emitted in the form of a photon. Instead, the energy is transferred to a third
charge carrier, which remains in the conduction band. This third charge carrier
relieves the accepted energy via lattice vibrations. As three particles are
involved in Auger recombination, this variant plays amajor role in highly doped
Fig. 1.8
As with recombinations, the effects on generation of charge carriers can be described
Generation by photons
Generation by high-energy particles
Generation by impact ionisation
Generation by photons can be regarded as the counterpart of band-to-band
recombination. Generation by charge carriers can occur through the energy of a photon
if its energy is sufficient to raise the charge carriers from the valence band to the
conduction band. The energy must therefore be greater than the bandgap energy E
Generation by high-energy particles is similar to that of photons, with the difference that
considerably more energy is supplied, which means that numerous new free charge
carriers are elicited. Generation by impact ionisation is the reverse of the Auger
recombination process. A charge carrier that has high energy (e.g. because it is
accelerated by an electrical field) can create a new electron-hole pair by releasing this
Named after the French physicist Pierre Victor Auger (1899 - 1993). Also known as Auger-Meitner
recombination, as Austrianphysicist LiseMeitner (1878 - 1968) had alreadydescribed the same effect.
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