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Radiative recombination may be understood as the opposite of optical generation. This recombination takes place if a free electron drops out of the conduction band and recombine with a free hole in the valance band and a photon of energy equivalent to the difference in starting and ending energy states is released. For direct bandgap semiconductors, radiative recombination is very significant, but not as relevant for indirect semiconductors such as silicon, since a photon must also be absorbed or expelled for an electron to complete the transmission.

Due to radiative processes the net recombination rate is expressed as:

(1.52)

Where B is a material constant.

For n-type semiconductors under low injection (p₀ ≤ p ≪ n₀) the net rate of recombination can be given as:

(1.53)

The effective lifetime due to radiative recombination, τλ,p, is given by:

(1.54)