Synthesis and characterization of kinked GaAs nanowires by Sb surfactant

Abstract In this study, GaAs/GaSb and GaAs/GaSb/GaAs heterostructure nanowires (NWs) were grown on Si (111) substrates by self-catalyzed vapor-liquid-solid (VLS) mechanism using the ultrahigh vacuum (UHV) molecular beam epitaxy (MBE) system. The GaAs/GaSb/GaAs heterojunction NWs may kink away from [111] to another crystallographic direction, as observed by electron microscopy. The smallest NWs prefer growth along the ⟨220⟩ axis, while the larger GaAs NWs chose either ⟨111⟩ or ⟨002⟩ axis, and the kink angles of 55°, 71°, 109°, 125°, and 145°, respectively. Moreover, significant lateral growth was observed at the GaSb segment in the GaAs/GaSb heterojunction NWs, and lateral growth was clearly evidenced by high-resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray (EDX) techniques. This behavior was attributed to the surfactant effect of Sb, leading to a significant change in the contact angle that ultimately caused the expansion of the Ga droplets. This study is also widely applicable to other III-V nanomaterials and provides conditions for the diversification of optoelectronic devices, such as photodetector or field-effect transistor.