  We explore the Bi-surfactant-directed self-assembly and structure of InAs
quantum dots grown on GaAs(110) by molecular beam epitaxy. The addition of a Bi
flux during InAs deposition changes the InAs growth mode from two-dimensional
(2D) Frank-van der Merwe to Stranski-Krastanov, resulting in the formation of
three-dimensional (3D) InAs islands on the surface. Furthermore, exposing
static InAs 2D layers to Bi induces a rearrangement of the strained layer into
3D islands. We explore the effect of varying the InAs thickness and Bi flux for
these two growth approaches, observing a critical thickness for 3D island
formation in both cases. Characterization of (110) InAs quantum dots with
high-resolution transmission electron microscopy reveals that larger islands
grown by the Stranski-Krastanov mode are plastically relaxed, while small
islands grown by the on-demand approach are coherent. Strain relaxation along
the [1-10] direction is achieved by 90 degree pure-edge dislocations with
dislocation lines running along [001]. In contrast, strain relief along [001]
is by 60 degree misfit dislocations. This behaviour is consistent with
observations of planar (In,Ga)As/GaAs(110) layers. These results illustrate how
surfactant Bi can provoke and control quantum dot formation where it normally
does not occur.
