Raman spectrum of Janus transition metal dichalcogenide monolayers WSSe and MoSSe

Abstract

Janus transition metal dichalcogenides (TMDs) lose the horizontal mirror symmetry of ordinary TMDs, leading to the emergence of additional features, such as native piezoelectricity, Rashba effect, and enhanced catalytic activity. While Raman spectroscopy is an essential nondestructive, phase- and composition-sensitive tool to monitor the synthesis of materials, a comprehensive study of the Raman spectrum of Janus monolayers is still missing. Here, we discuss the Raman spectra of WSSe and MoSSe measured at room and cryogenic temperatures, near and off resonance. By combining polarization-resolved Raman data with calculations of the phonon dispersion and using symmetry considerations, we identify the four first-order Raman modes and higher-order two-phonon modes. Moreover, we observe defect-activated phonon processes, which provide a route toward a quantitative assessment of the defect concentration and, thus, the crystal quality of the materials synthesized. Our work establishes a solid background for future research on material synthesis, study, and application of Janus TMD monolayers.

arXiv comment12 pages, 7 figures, 2 tables

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Cited by in corpus (11)

• One pot chemical vapor deposition of high optical quality large area monolayer Janus transition metal dichalcogenides
• Exciton spectroscopy and diffusion in MoSe2-WSe2 lateral heterostructures encapsulated in hexagonal boron nitride
• Strain Anisotropy Driven Spontaneous Formation of Nanoscrolls from Two-Dimensional Janus Layers
• Nonlinear Dispersion Relation and Out-of-Plane Second Harmonic Generation in MoSSe and WSSe Janus Monolayers
• Breakdown of the static dielectric screening approximation of Coulomb interactions in atomically thin semiconductors
• Phonon anharmonicity and thermal conductivity of two-dimensional van der Waals materials: A review
• Abnormal Phonon Angular Momentum due to Off-diagonal Elements in Density Matrix induced by Temperature Gradient
• Spin-orbit correlations and exchange-bias control in twisted Janus dichalcogenide multilayers
• Utilizing the Janus MoSSe surface polarization in designing complementary metal-oxide-semiconductor field-effect transistors
• Atomically-precise synthesis and simultaneous integration of 2D transition metal dichalcogenides enabled by nano-confinement
• Raman Digital Twin of Monolayer Janus Transition Metal Dichalcogenides