Raman spectrum of Janus transition metal dichalcogenide monolayers WSSe and MoSSe

Marko M. Petrić, Malte Kremser, Matteo Barbone, Ying Qin, Yasir Sayyad, Yuxia Shen, Sefaattin Tongay, Jonathan J. Finley, Andrés R. Botello-Méndez, Kai Müller

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


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. Our work establishes a solid background for future research on material synthesis, study, and application of Janus TMD monolayers.

Original languageEnglish (US)
Article number035414
JournalPhysical Review B
Issue number3
StatePublished - Jan 15 2021

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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