American Chemical Society, Chemistry of Materials, 9(27), p. 3408-3416, 2015
DOI: 10.1021/acs.chemmater.5b00697
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One-dimensional nanostructures with controllable morphologies and defects are appealing for use in nanowire devices. This paper details the influence of colloidal magnetite iron oxide nanoparticle seeds to regulate the radial dimension and twin boundary formation in Ge nanowires grown through a liquid-injection chemical vapor deposition process. Control over the mean nanowire diameter, even in the sub-10 nm regime, was achieved due to the minimal expansion and aggregation of iron oxide nanoparticles during the growth process. The uncommon occurrence of heterogeneously distributed multiple layer {111} twins, directed perpendicular to the nanowire growth axis, were also observed in <111>-directed Ge nanowires, especially those synthesized from patterned hemispherical Fe3O4 nanodot catalysts. Consecutive twin planes along <111>-oriented nanowires resulted in a local phase transformation from 3C diamond cubic to hexagonal 4H allotropes. Localized polytypic crystal phase heretostructures were also formed along <111>-oriented Ge nanowire using magnetite nanodot catalysts.