Effect of precursor flux on compositional evolution in InP1−xSbx nanowires grown via self-catalyzed vapor–liquid–solid process

We investigated the effect of high flow rates (> 10−5 mol/min) of metalorganic precursors on compositional evolution in indium phosphide antimonide (InP1−xSbx) nanowires grown via chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates maintained at ∼360 °C. The as-grown nanowire morphology, composition, and crystallinity are determined using scanning and transmission electron microscopies, selected-area electron diffraction, and x-ray energy dispersive spectroscopy. For all of the precursor flow rates, we obtain zinc blende structured InP1-xSbx wires that are tapered with wider tops, narrower bases, and In-rich In–Sb alloy tips—characteristic of the vapor–liquid–solid process. The Sb content within the InP1−xSbx wires is found to increase non-linearly with increasing Sb precursor flow rate. At the interfaces between the In–Sb alloy tips and the InP1-xSbx nanowires, we observe single-crystalline wurtzite-structured InSb segments whose volumes depend on the Sb precursor flow rate. We attribute this phenomenon to the rapid crystallization of InSb during cooling of the Sb-rich In–Sb alloy droplets.

► We used MOCVD to investigate the effect of high precursor flow rates on compositional evolution during the self-catalyzed growth of In(P,Sb) alloy nanowires.
► Detailed electron microscopy characterization was carried out.
► It was found that the Sb composition in the nanowires increased with increasing Sb flow rates.
► We observed a WZ-structured InSb crystalline segment at the nanowire–catalyst interface.
► We suggest that this phenomenon is a direct result of Sb supersaturation in the droplets.