Phase Separation Induced by Au Catalysts in Ternary InGaAs Nanowires

• Published in: Nano letters Vol. 13; no. 2; pp. 643 - 650
• Main Authors: Guo, Ya-Nan, Xu, Hong-Yi, Auchterlonie, Graeme J, Burgess, Tim, Joyce, Hannah J, Gao, Qiang, Tan, Hark Hoe, Jagadish, Chennupati, Shu, Hai-Bo, Chen, Xiao-Shuang, Lu, Wei, Kim, Yong, Zou, Jin
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.02.2013
• Subjects: Catalysis; Catalysts; Catalytic methods; Concentration (composition); Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electron states; Exact sciences and technology; Flow rate; Gallium arsenides; Gold; Materials science; Methods of electronic structure calculations; Methods of nanofabrication; Nanocrystalline materials; Nanoscale materials and structures: fabrication and characterization; Nanowires; Phase separation; Physics; Precursors; Quantum wires; In x Ga1‑x As; phase separation; ternary semiconductors; core−shell nanowires; III−V semiconductor nanowires; Gold; Gallium arsenides; Catalysts; Core shell structure; MOCVD; Precursor; Indium arsenides; III-V compound; Transmission electron microscopy; Phase separation; Growth mechanism; Density functional method; Alloying; Nanowires; Nanostructured materials; III-V semiconductors
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl304237b

We report a novel phase separation phenomenon observed in the growth of ternary In x Ga1‑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 Ga1‑x As nanowires high precursor flow rates generate ternary In x Ga1‑x As cores with In-rich shells, while low precursor flow rates produce binary GaAs cores with ternary In x Ga1‑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.