3D Atomic-Scale Insights into Anisotropic Core–Shell-Structured InGaAs Nanowires Grown by Metal–Organic Chemical Vapor Deposition

III–V ternary InGaAs nanowires have great potential for electronic and optoelectronic device applications; however, the 3D structure and chemistry at the atomic-scale inside the nanowires remain unclear, which hinders tailoring the nanowires for specific applications. Here, atom probe tomography is used in conjunction with a first-principles simulation to investigate the 3D structure and chemistry of InGaAs nanowires, and reveals i) the nanowires form a spontaneous core–shell structure with a Ga-enriched core and an In-enriched shell, due to different growth mechanisms in the axial and lateral directions; ii) the shape of the core evolves from hexagon into Reuleaux triangle and grows larger, which results from In outward and Ga inward interdiffusion occurring at the core–shell interface; and iii) the irregular hexagonal shell manifests an anisotropic growth rate on {112}A and {112}B facets. Accordingly, a model in terms of the core–shell shape and chemistry evolution is proposed, which provides fresh insights into the growth of these nanowires.

Spontaneous core–shell InGaAs nanowires are grown by metal–organic chemical vapor deposition and investigated with atom probe tomography, transmission electron microscopy, and density functional theory. The results reveal that a Ga-rich core coarsens from hexagonal to triangular due to species uphill interdiffusion, and an In-rich shell is owing to a surface catalyst effect, interdiffusion, and low formation energy. A hexagonal-shaped shell results from anisotropic growth on a {112}A and B facet.

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