Abstract
The nanowire geometry is favorable for the growth of ternary semiconductor materials, because the composition and properties can be tuned freely without substrate lattice matching. To achieve precise control of the composition in ternary semiconductor nanowires, a deeper understanding of the growth is required. One unknown aspect of seeded nanowire growth is how the composition of the catalyst nanoparticle affects the resulting composition of the growing nanowire. We report the first in situ measurements of the nanoparticle and InxGa1–xAs nanowire compositional relationship using an environmental transmission electron microscopy setup. The compositions were measured and correlated during growth, via X-ray energy dispersive spectroscopy. Contrary to predictions from thermodynamic models, the experimental results do not show a miscibility gap. Therefore, we construct a kinetic model that better predicts the compositional trends by suppressing the miscibility gap. The findings imply that compositional control of InxGa1–xAs nanowires is possible across the entire compositional range.
Highlights
The nanowire geometry is favorable for the growth of ternary semiconductor materials, because the composition and properties can be tuned freely without substrate lattice matching
One of the two most common ways to grow epitaxial III−V semiconductor nanowires is through metal organic vapor phase epitaxy (MOVPE) [the other being molecular beam epitaxy (MBE)]
The growth of InGaAs nanowires has been studied in situ using an environmental transmission electron microscope (TEM)
Summary
The experiments were carried out in a Hitachi HF3300S environmental TEM, integrated with a custom-built MOVPE system. Blaze software by Hitachi is used to resistively heat the central area of the chips during the experiments This area consists of a thin SiNx film, with circular openings in the material where the electron beam can pass through unobstructed. Because there is no substrate with which the direct electron beam can interact in the openings, most of the collected signal comes from the interaction between the electron beam and the nanowire or nanoparticle. This ensures the best spatial resolution when recording images and videos and the least stray X-ray signal from the surrounding film when recording spectra. Further details about the model, details about EDX data acquisition and treatment, and an error estimation of the experimental data shown in panels a and b of Figure 2 (PDF)
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