Phase separation induced by Au catalysts in ternary InGaAs nanowires.

Guo, Ya-Nan; Xu, Hong-Yi; Auchterlonie, Graeme J; Burgess, Tim; Joyce, Hannah J; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati et al. · Nano Lett · 2013

basic_science · Level V

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Abstract

We report a novel phase separation phenomenon observed in the growth of ternary In(x)Ga(1-x)As nanowires by metalorganic chemical vapor deposition. A spontaneous formation of core-shell nanowires is investigated by cross-sectional transmission electron microscopy, revealing the compositional complexity within the ternary nanowires. It has been found that for In(x)Ga(1-x)As nanowires high precursor flow rates generate ternary In(x)Ga(1-x)As cores with In-rich shells, while low precursor flow rates produce binary GaAs cores with ternary In(x)Ga(1-x)As shells. First-principle calculations combined with thermodynamic considerations suggest that this phenomenon is due to competitive alloying of different group-III elements with Au catalysts, and variations in elemental concentrations of group-III materials in the catalyst under different precursor flow rates. This study shows that precursor flow rates are critical factors for manipulating Au catalysts to produce nanowires of desired composition.