title: Anomalous Strain Relaxation in Core-Shell Nanowire Heterostructures via Simultaneous Coherent and Incoherent Growth.
abstract: Nanoscale substrates such as nanowires allow heterostructure design to venture well beyond the narrow lattice mismatch range restricting planar heterostructures, owing to misfit strain relaxing at the free surfaces and partitioning throughout the entire nanostructure. In this work, we uncover a novel strain relaxation process in GaAs/InxGa1-xAs core-shell nanowires that is a direct result of the nanofaceted nature of these nanostructures. Above a critical lattice mismatch, plastically relaxed mounds form at the edges of the nanowire sidewall facets. The relaxed mounds and a coherent shell grow simultaneously from the beginning of the deposition with higher lattice mismatches increasingly favoring incoherent mound growth. This is in stark contrast to Stranski-Krastanov growth, where above a critical thickness coherent layer growth no longer occurs. This study highlights how understanding strain relaxation in lattice mismatched nanofaceted heterostructures is essential for designing devices based on these nanostructures.
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Ryan B
authors.identifier: 0000-0002-7216-3541
authors.initials: RB
authors.lastname: Lewis
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Nicolai
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Hanno
authors.initials: H
authors.lastname: Küpers
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Manfred
authors.initials: M
authors.lastname: Ramsteiner
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Achim
authors.initials: A
authors.lastname: Trampert
authors.affiliation: Paul-Drude-Institut für Festkörperelektronik , Hausvogteiplatz 5-7, 10117 Berlin, Germany.
authors.forename: Lutz
authors.initials: L
authors.lastname: Geelhaar
keywords: GaAs; Nanowires; X-ray diffraction; core−shell; molecular beam epitaxy; semiconductor; strain relaxation; transmission electron microscopy