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

A systematic theoretical study of the electronic and optical properties of Ga1-xInxAs self-assembled quantum wires (QWRs) made of short-period superla ttices with strain-induced lateral ordering is presented. The theory is bas ed on the effective bond-orbital model combined with a valence-force-field (VFF) model. Valence-band anisotropy, band mixing, and effects due to local strain distribution at the atomistic level are all taken into account. Sev eral structure models with varying degrees of alloy mixing for lateral modu lation are considered. A VFF model is used to find the equilibrium atomic p ositions in the QWR structure by minimizing the lattice energy. The strain tensor at each atomic (In or Ga) site is then obtained and included in the calculation of electronic states and optical properties. It is found that d ifferent local arrangement of atoms leads to very different strain distribu tion, which in turn alters the optical properties. In particular, we find t hat in model structures with thick capping layer the electrons and holes ar e confined in the Ga-rich region and the optical anisotropy can be reversed due to the variation of lateral alloy mixing, while for model structures w ith thin capping layer the electrons and holes are confined in the In-rich region, and the optical anisotropy is much less sensitive to the lateral al loy mixing. (C) 2001 American Institute of Physics.