Effects of interdiffusion on the sub-band-edge structure of In0.53Ga0.47As/InP single quantum wells

Abstract

The disordering of In0.53Ga0.47As/InP single quantum wells has been studied using an error function distribution to model the compositional profile after interdiffusion. When considering interdiffusion on the group-III sublattice only, a large strain buildup results during the early stages of disordering. Details are presented showing how this interdiffusion and the effects of strain lead to an interesting carrier confinement profile which differs from that of disordered AlGaAs/GaAs and InGaAs/GaAs quantum-well structures. An abrupt confinement profile is maintained even after significant interdiffusion, with a well width equal to that of the as-grown quantum well. The combined effects of strain with the unstrained band-gap profile results in a potential buildup in the barrier near the interface, while it gives rise to two ‘‘miniwells’’ inside the potential wells. The sub-band-edge structure shows that the potential buildup can result in quasibound subband states, while the heavy-hole well can support the ground state within the miniwells. In contrast, when identical interdiffusion on both group-III and group-V sublattices is considered, the structure remains lattice matched, the confinement profile changes to that of a graded profile, and the ground-state transition energy shifts to shorter wavelengths.