title: Sharpening the Interfaces of Axial Heterostructures in Self-Catalyzed AlGaAs Nanowires: Experiment and Theory.
abstract: The growth of III-III-V axial heterostructures in nanowires via the vapor-liquid-solid method is deemed to be unfavorable because of the high solubility of group III elements in the catalyst droplet. In this work, we study the formation by molecular beam epitaxy of self-catalyzed GaAs nanowires with AlxGa1-xAs insertions. The composition profiles are extracted and analyzed with monolayer resolution using high-angle annular dark-field scanning transmission electron microscopy. We test successfully several growth procedures to sharpen the heterointerfaces. For a given nanowire geometry, prefilling the droplet with Al atoms is shown to be the most efficient way to reduce the width of the GaAs/AlxGa1-xAs interface. Using the thermodynamic data available in the literature, we develop numerical and analytical models of the composition profiles, showing very good agreement with experiments. These models suggest that atomically sharp interfaces are attainable for catalyst droplets of small volumes.
authors: Laboratoire de Photonique et de Nanostructures, CNRS, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France.
authors: Giacomo
authors: G
authors: Priante
authors: Laboratoire de Photonique et de Nanostructures, CNRS, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France.
authors: Frank
authors: F
authors: Glas
authors: Laboratoire de Photonique et de Nanostructures, CNRS, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France.
authors: Gilles
authors: G
authors: Patriarche
authors: Laboratoire de Photonique et de Nanostructures, CNRS, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France.
authors: Konstantinos
authors: K
authors: Pantzas
authors: Laboratoire de Photonique et de Nanostructures, CNRS, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France.
authors: Fabrice
authors: F
authors: Oehler
authors: Laboratoire de Photonique et de Nanostructures, CNRS, Université Paris-Saclay , Route de Nozay, 91460 Marcoussis, France.
authors: Jean-Christophe
authors: JC
authors: Harmand
keywords: AlGaAs; HAADF; Nanowires; heterostructure; interfaces; self-catalyzed