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Lattice Dynamics of the Rhenium and Technetium Dichalcogenides

The rhenium and technetium dichalcogenides are layered van der Waals semiconductors which show a large number of Raman-active zone-centre phonon modes as a result of their unusually large unit cells and deviation from hexagonal symmetry. They thus offer the possibility of introducing in-plane anisot...

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Detalles Bibliográficos
Autores principales: Wolverson, Daniel, Hart, Lewis S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer US 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4870478/
https://www.ncbi.nlm.nih.gov/pubmed/27178055
http://dx.doi.org/10.1186/s11671-016-1459-9
Descripción
Sumario:The rhenium and technetium dichalcogenides are layered van der Waals semiconductors which show a large number of Raman-active zone-centre phonon modes as a result of their unusually large unit cells and deviation from hexagonal symmetry. They thus offer the possibility of introducing in-plane anisotropy into composite heterostructures based on van der Waals materials, and Raman spectroscopy is generally used to determine their in-plane orientation. We show that first-principles calculations give a good description of the lattice dynamics of this family of materials and thus predict the zone-centre phonon frequencies and Raman activities of TcS(2). We consider the distribution of the phonon modes in frequency and their atomic displacements and give a unified understanding of the phonon frequencies and Raman spectra of ReS(2), TcS(2) and ReSe(2) in terms of the scaling of Raman frequency with the chalcogen mass.