Controlling the morphology, composition and crystal structure in gold-seeded GaAs_1-xSb_x nanowires

While III-V binary nanowires are now well controlled and their growth mechanisms reasonably well understood, growing ternary nanowires, including controlling their morphology, composition and crystal structure remains a challenge. However, understanding and control of ternary alloys is of fundamental interest and critical to enable a new class of nanowire devices. Here, we report on the progress in understanding the complex growth behaviour of gold-seeded GaAs_1-xSb_x nanowires grown by metalorganic vapour phase epitaxy. The competition between As and Sb atoms for incorporation into the growing crystal leads to a tunability of the Sb content over a broad range (x varies from 0.09 to 0.6), solely by changing the AsH₃ flow. In contrast, changing TMSb flow is more effective in affecting the morphology and crystal structure of the nanowires. Inclined faults are found in some of these nanowires and directly related to the kinking of the nanowires and controlled by TMSb flow. Combined with the observed sharp increase of wetting angle between the Au seed and nanowire, the formation of inclined faults are attributed to the Au seed being dislodged from the growth front to wet the sidewalls of the nanowires, and are related to the surfactant role of Sb. The insights provided by this study should benefit future device applications relying on taper- and twin-free ternary antimonide III-V nanowire alloys and their heterostructures.