GaAs nanowires were grown by molecular-beam epitaxy on (111)B oriented surfaces, after the deposition of Au nanoparticles. Different growth durations and different growth terminations were tested. After the growth of the nanowires, the structure and the composition of the metallic particles were analyzed by transmission electron microscopy and energy dispersive x-ray spectroscopy. We identified three different metallic compounds: the hexagonal β′Au7Ga2 structure, the orthorhombic AuGa structure, and an almost pure Au face centered cubic structure. We explain how these different solid phases are related to the growth history of the samples. It is concluded that during the wire growth, the metallic particles are liquid, in agreement with the generally accepted vapor-liquid-solid mechanism. In addition, the analysis of the wire morphology indicates that Ga adatoms migrate along the wire sidewalls with a mean length of about 3μm.

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This work reports on the influence of the InP cap-layer growth rate on the structural and optical properties of InAs∕InP quantum dots (QDs) grown by metal-organic vapor phase epitaxy. A careful correlation between the structural and optical properties of the QDs completed by a modeling of their interband transition energy evidences the presence of different QD families with heights varying by monolayer steps. The analysis of transmission electron microscopy images and photoluminescence spectra demonstrates a drastic decrease of the QD height during the growth of the InP cap layer, due to As∕P exchange. The efficiency of this erosion mechanism is shown to be strongly related to the QD exposure time to PH3, depending on the growth rate of the InP cap layer.

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