Highly Strained InAs/GaAs Short Period Superlattices

Abstract

InAs/GaAs short period superlattices (SPS) are highly strained heterostructures (7% lattice mismatch between InAs and GaAs) which can be grown approximately lattice matched to InP. Such SPS thus constitute an ordered counterpart of the In_xGa_{l_x} As random alloy. A larger mobility (at low temperature mainly) can be surmized for this artificially layered structure due to the suppression of alloy scattering. Due to the change from a T_dcubic (in InGaAs) to a D_2d tetragonal symmetry in InAs/GaAs SPS), marked qualitative differences are also expected between these two materials’ band structures. An anisotropy of the electron effective mass, and a lifting of the valence band degeneracy are for example expected in the SPS. Both transport and optical properties might thus be quite different in these two materials, and open interesting opportunities for this ordered alloy in the field of devices. Among others, a larger spin-orbit splitting would reduce the efficiency of the Auger nonradiative process when compared to InGaAs.