Edge phonons in layered orthorhombic GeS and GeSe monochalcogenides
Tipo
Artigo
Data de publicação
2019
Periódico
Physical Review B
Citações (Scopus)
20
Autores
Ribeiro H.B.
Ramos S.L.L.M.
Seixas L.
De Matos C.J.S.
Pimenta M.A.
Ramos S.L.L.M.
Seixas L.
De Matos C.J.S.
Pimenta M.A.
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Resumo
© 2019 American Physical Society.Germanium sulfide (GeS) and germanium selenide (GeSe) are layered orthorhombic crystals whose structure bears a strong resemblance with that of black phosphorus and, additionally, are expected to exhibit high piezoelectricity in the few layer domain. In this work, we investigate the Raman properties of exfoliated GeS and GeSe and show that their edges exhibit unusual polarized Raman features that were first observed in black phosphorus. The results include the activation in the spectra of otherwise not allowed modes at the edges of the sample, depending on the crystallographic direction of the edge and the polarization configuration used in the measurements. These features are attributed to atomic rearrangements at the crystal terminations, as well as their impact on phonon symmetries, similar to the case of black phosphorus. Our conclusions are further corroborated by using density functional theory and suggest that edge rearrangements, which will have an impact on the mechanical, electronic, and chemical properties of devices, is a general phenomenon of orthorhombic layered structures.
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Atomic rearrangements , Crystallographic directions , Germanium sulfide , High piezoelectricities , Layered orthorhombic , Layered Structures , Monochalcogenides , Raman properties