Effect of strain on CHSH Auger recombination in strained In0.53+xGa0.47-xAs on InP

We calculate the |conduction, heavy hole⟩- |split-off hole, heavy hole⟩ (CHSH) Auger rates in strained In_0.53+xGa _0.47-xAs on InP, a widely used material system for quantum well lasers. The bandstructure is obtained from an eight-band tight binding model with spin-orbit coupling, strain effects being included via the deformation potential theory. Adding excess In decreases the hole density of states: this effect acts to decrease the Auger rates. The excess In also decreases the bandgap, however, and increases the split-off gap: these effects act to increase the Auger rates. When we include both of these effects we find that the reduction in the net bandgap dominates; hence, the Auger rates increase with excess In for a fixed carrier concentration. We include these Anger rates in the threshold current calculation for a strained layer multi quantum well laser. We find that for x<0.15 the strain-induced reduction in the threshold carrier concentration is able to offset the higher Auger rates; thus, the threshold current decreases rapidly with x. For x>0.15, however, the threshold carrier concentration changes little and the Anger rates continue to increase; thus, the threshold current begins to increase rapidly with x