1. Fabrication of core-shell nanostructures via silicon on insulator dewetting and germanium condensation: towards a strain tuning method for SiGe-based heterostructures in a three-dimensional geometry
- Author
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Abdelmalek Benkouider, Antoine Ronda, Luc Favre, Martiane Cabié, Marco Abbarchi, Meher Naffouti, Thomas David, Isabelle Berbezier, Institut des Matériaux, de Microélectronique et des Nanosciences de Provence (IM2NP), Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU), and Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Nanostructure ,Materials science ,Silicon on insulator ,chemistry.chemical_element ,Bioengineering ,Nanotechnology ,Germanium ,02 engineering and technology ,01 natural sciences ,7. Clean energy ,Monocrystalline silicon ,0103 physical sciences ,General Materials Science ,Dewetting ,[SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics ,Electrical and Electronic Engineering ,010302 applied physics ,Thermal oxidation ,business.industry ,Mechanical Engineering ,Heterojunction ,General Chemistry ,021001 nanoscience & nanotechnology ,chemistry ,Mechanics of Materials ,Optoelectronics ,0210 nano-technology ,business ,Molecular beam epitaxy - Abstract
International audience; We report on a novel method for the implementation of core-shell SiGe-based nanocrystals combining silicon on insulator dewetting in a molecular beam epitaxy reactor with an ex situ Ge condensation process. With an in situ two-step process (annealing and Ge deposition) we produce two families of islands on the same sample: Si-rich, formed during the first step and, all around them, Ge-rich formed after Ge deposition. By increasing the amount of Ge deposited on the annealed samples from 0 to 18 monolayers, the islands' shape in the Si-rich zones can be tuned from elongated and flat to more symmetric and with a larger vertical aspect ratio. At the same time, the spatial extension of the Ge-rich zones is progressively increased as well as the Ge content in the islands. Further processing by ex situ rapid thermal oxidation results in the formation of a core-shell composition profile in both Si and Ge-rich zones with atomically sharp heterointerfaces. The Ge condensation induces a Ge enrichment of the islands' shell of up to 50% while keeping a pure Si core in the Si-rich zones and a similar to 25% SiGe alloy in the Ge-rich ones. The large lattice mismatch between core and shell, the absence of dislocations and the islands' monocrystalline nature render this novel class of nanostructures a promising device platform for strain-based band-gap engineering. Finally, this method can be used for the implementation of ultralarge scale meta-surfaces with dielectric Mie resonators for light manipulation at the nanoscale.
- Published
- 2016