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Threefold rotational symmetry in hexagonally shaped core–shell (In,Ga)As/GaAs nanowires revealed by coherent X-ray diffraction imaging

Coherent X-ray diffraction imaging at symmetric hhh Bragg reflections was used to resolve the structure of GaAs/In(0.15)Ga(0.85)As/GaAs core–shell–shell nanowires grown on a silicon (111) substrate. Diffraction amplitudes in the vicinity of GaAs 111 and GaAs 333 reflections were used to reconstruct...

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Detalles Bibliográficos
Autores principales: Davtyan, Arman, Krause, Thilo, Kriegner, Dominik, Al-Hassan, Ali, Bahrami, Danial, Mostafavi Kashani, Seyed Mohammad, Lewis, Ryan B., Küpers, Hanno, Tahraoui, Abbes, Geelhaar, Lutz, Hanke, Michael, Leake, Steven John, Loffeld, Otmar, Pietsch, Ullrich
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5458586/
https://www.ncbi.nlm.nih.gov/pubmed/28656032
http://dx.doi.org/10.1107/S1600576717004149
Descripción
Sumario:Coherent X-ray diffraction imaging at symmetric hhh Bragg reflections was used to resolve the structure of GaAs/In(0.15)Ga(0.85)As/GaAs core–shell–shell nanowires grown on a silicon (111) substrate. Diffraction amplitudes in the vicinity of GaAs 111 and GaAs 333 reflections were used to reconstruct the lost phase information. It is demonstrated that the structure of the core–shell–shell nanowire can be identified by means of phase contrast. Interestingly, it is found that both scattered intensity in the (111) plane and the reconstructed scattering phase show an additional threefold symmetry superimposed with the shape function of the investigated hexagonal nanowires. In order to find the origin of this threefold symmetry, elasticity calculations were performed using the finite element method and subsequent kinematic diffraction simulations. These suggest that a non-hexagonal (In,Ga)As shell covering the hexagonal GaAs core might be responsible for the observation.