Systematic study of Ga1−xInxAs self-assembled quantum wires with varying interfacial strain relaxation

A systematic theoretical study of the electronic and optical properties ofGa$_{1-x}$In$_x$As self-assembled quantum-wires (QWR's) made of short-periodsuperlattices (SPS) with strain-induced lateral ordering is presented. Thetheory is based on the effective bond-orbital model (EBOM) combined with avalence-force field (VFF) model. Valence-band anisotropy, band mixing, andeffects due to local strain distribution at the atomistic level are all takeninto account. Several structure models with varying degrees of alloy mixing forlateral modulation are considered. A valence force field model is used to findthe equilibrium atomic positions in the QWR structure by minimizing the latticeenergy. The strain tensor at each atomic (In or Ga) site is then obtained andincluded in the calculation of electronic states and optical properties. It isfound that different local arrangement of atoms leads to very different straindistribution, which in turn alters the optical properties. In particular, wefound that in model structures with thick capping layer the electron and holeare confined in the Ga-rich region and the optical anisotropy can be reverseddue to the variation of lateral alloying mixing, while for model structureswith thin capping layer the electron and hole are confined in the In-richregion, and the optical anisotropy is much less sensitive to the lateral alloymixing.Comment: 23 pages, and 8 figure