Accurate Bloch function overlap integrals and anisotropic energy band structures derived from the same band structure calculations have been used for the first time in the computation of impact ionisation and Auger recombination rates for the ccch transition in InSb and In0.72Ga 0.28As0.6P0.4. The small-signal Auger lifetimes in InSb are shown to be more affected by the anisotropy of the energy bands than by the anisotropy of the overlap integrals. The large-signal lifetimes in InGaAsP are found to be greater by between one and two orders of magnitude than those obtained in previous theoretical calculations which had used approximate estimates for the overlap integrals. In impact ionisation the use of accurate overlap integrals introduces an additional degree of 'softness' into the threshold so that for a given direction the transition probability rate varies as (E-ET)3 for an electron of energy E near the threshold energy ET, and the direction-averaged probability rate varies as (E-ET(minimum))4.
