Lattice Dynamics of the Rhenium and Technetium Dichalcogenides

Daniel Wolverson, Lewis Hart

OAI: oai:purehost.bath.ac.uk:publications/32c0778c-ff7a-4af7-9cac-21f3339d5e81 • DOI: https://doi.org/10.1186/s11671-016-1459-9

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 TcS2. 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 ReS2, TcS2 and ReSe2 in terms of the scaling of Raman frequency with the chalcogen mass.

Rhenium sulphide Technetium sulphide Rhenium selenide Transition metal dichalcogenide Raman spectroscopy