The direct (radiative) recombination is of importance for direct bandgap
semiconductors. In Si, Ge, and GaP it is of no
significance for all possible conditions [188]. The recombination rate
is proportional to the carrier concentrations and is modeled using the
following equation

(3.151)

The coefficients
have constant values from Table 3.37.

Table 3.37:
Parameter values for the radiative recombination model