Microscopic Description of Nanostructures Grown on (N11) Surfaces

Abstract

We report on a theoretical study of GaAs/InGaAs based nanostructures grown along the [N11] direction. The elastic deformations of the structures were calculated by means of the continuum elasticity theory, taking into account commensurability constraints at the interfaces. The strained atomic positions were derived, as well as the strain induced piezoelectric polarizations and electric fields. These data were used as an input for the calculation of the fundamental electronic transitions of our systems within the empirical tight-binding approach. These results are compared with the envelope function methods. We applied our approach to a (211) oriented InAs quantum dot embedded in a GaAs matrix, and to a (311) oriented InGaAs quantum wire, embedded in AlGaAs barriers. In both cases, we obtained a non-symmetric elastic deformation due to the lower symmetry of (N11)-oriented structures. Moreover, the atomic displacements and the strain induced piezoelectric potential induce a separation of the hole and electron wave functions, which are shifted from the dot center.