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

Abstract

A systematic theoretical study of the electronic and optical properties of Ga 1−x In x As self-assembled quantum-wires (QWR's) made of short-period superlattices (SPS) with strain-induced lateral ordering is presented. The theory is based on the effective bond-orbital model (EBOM) 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. Several structure models with varying degrees of alloy mixing for lateral modulation are considered. A valence force field model is used to find the equilibrium atomic positions 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 different local arrangement of atoms leads to very different strain distribution, which in turn alters the optical properties. In particular, we found that in model structures with thick capping layer the electron and hole are confined in the Ga-rich region and the optical anisotropy can be reversed due to the variation of lateral alloying mixing, while for model structures with thin capping layer the electron and hole are confined in the In-rich region, and the optical anisotropy is much less sensitive to the lateral alloy mixing.

The Electronic Structure and Transmission Characteristics of Disordered AlGaAs Nanowires

“…Most often the theoretical approach is of the effective-mass or k.p-type due to the computationally challenging nature of nanowire calculations [1]- [5]. Recently, however, more complete, multiband calculations based on methods such as pseudopotentials [6], tight-binding [7]- [10], or the bond-orbital model [11], [12] have appeared. Regardless of the theoretical method employed, two broad classes of calculation are important for nanowires: transport and bandstructure.…”

“…Because the virtual-crystal approximation (VCA) can accurately reproduce some bulk gaps and masses it is generally used for bandstructure and transport calculations [7], [8], [11], [12]. When evaluating the VCA (in any of its various formulations) for use in nanostructures it must be remembered that under it, all primitive cells are the same, being composed of identical pseudoatoms chosen to mimic bulk behavior.…”