Auger recombination at double donors

Double donors are deep impurities which are favourable for Auger recombination. The cross section of this recombination process and its temperature dependence are calculated for double donors in indirect-band-gap semiconductors (for instance S, Se and Te in Si). Because of the uncertainty of the impurity wavefunction, the cross section covers a wide range (10 -14 -10 -19 cm 2 ). The temperature dependence is only in agreement with experiments if the influence of lattice relaxation is taken into account. A remarkable point is the independence of this process with respect to the carrier density which is also observed in other cases. The analogous problem of a double acceptor (Zn in Si) is discussed.