Theory of donor-acceptor radiative and Auger recombination in simple semiconductors

Abstract

The donor-acceptor radiative and Auger transitions have been investigated theoretically for the simple model of a direct semiconductor with parabolic bands and a random distribu­tion of hydrogenic impurities. Both effects have been estimated as a function of donor-acceptor separation R , and expressions for the rates (when summed over all R ) have also been obtained. The results have been evaluated for GaAs at 80 K and for CdS at 1.6 K to facilitate comparison with experiment. The radiative calculations agree with the experimental results both as regards the numerical value in the limit R → 0 and also as regards the R -dependence. For the usual concentrations the radiative transitions are found to dominate in these materials. The Auger effect is likely to be a serious competitor only for electron collisions when n > 10 20 cm -3 .