Bismuth-surfactant-induced growth and structure of InAs/GaAs(110) quantum dots

Abstract

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 [110] direction is achieved by 90 pure-edge dislocations with dislocation lines running along [001]. In contrast, strain relief along [001] is by 60 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.

Coaxial GaAs/(In,Ga)As Dot-in-a-Well Nanowire Heterostructures for Electrically Driven Infrared Light Generation on Si in the Telecommunication O Band

“…Furthermore, for the same reason the actual shape of the QDs and details like possible intermixing cannot be deduced from these data. However, studies of Bi-induced QDs grown on GaAs(110) planar surfaces and NW side walls suggest the presence of a wetting layer and a QD shape with a much larger width than height. ,, The determination of the actual In content and distribution within the QDs introduced here, as well as their precise shape, would require additional advanced microstructural characterization beyond the scope of this work. , …”

“…We believe the corresponding optimization of the QD size distribution could possibly be achieved by modifying the way to induce QD formation with Bi. In particular, we recently reported that InAs QD formation can be triggered by exposing static InAs 2D layers to Bi, which induces a rearrangement of the strained layer into 3D islands on planar GaAs(110) surfaces …”

“…However, studies of Bi-induced QDs grown on GaAs(110) planar surfaces and NW side walls suggest the presence of a wetting layer and a QD shape with a much larger width than height. 21,26,27 The determination of the actual In content and distribution within the QDs introduced here, as well as their precise shape, would require additional advanced microstructural characterization beyond the scope of this work. 19,28 The luminescence of the DWELL NWs is first studied by CL spectroscopy as presented in the upper part of Figure 3 (Figure 3a−d).…”

“…In particular, we recently reported that InAs QD formation can be triggered by exposing static InAs 2D layers to Bi, which induces a rearrangement of the strained layer into 3D islands on planar GaAs(110) surfaces. 27…”

Growth of InAs(Bi)/GaAs Quantum Dots under a Bismuth Surfactant at High and Low Temperature

“…High QD uniformity is also desirable in these structures, particularly for laser applications in order to reduce threshold currents [5]. Surfactant deposition during QD growth has been shown to have a significant impact on the size and uniformity of InAs QDs as well as impacting QD density [14][15][16][17][18][19][20][21][22][23][24].…”