Low-Frequency Raman Fingerprints of Two-Dimensional Metal Dichalcogenide Layer Stacking Configurations

Alexander A. Puretzky, Liangbo Liang, Xufan Li, Kai Xiao, Kai Wang, Masoud Mahjouri-Samani, Leonardo Basile, Juan Carlos Idrobo, Bobby G. Sumpter, Vincent Meunier, David B. Geohegan

Research output: Contribution to journalArticlepeer-review

152 Scopus citations

Abstract

The tunable optoelectronic properties of stacked two-dimensional (2D) crystal monolayers are determined by their stacking orientation, order, and atomic registry. Atomic-resolution Z-contrast scanning transmission electron microscopy (AR-Z-STEM) and electron energy loss spectroscopy (EELS) can be used to determine the exact atomic registration between different layers, in few-layer 2D stacks; however, fast optical characterization techniques are essential for rapid development of the field. Here, using two- and three-layer MoSe2 and WSe2 crystals synthesized by chemical vapor deposition, we show that the generally unexplored low frequency (LF) Raman modes (<50 cm-1) that originate from interlayer vibrations can serve as fingerprints to characterize not only the number of layers, but also their stacking configurations. Ab initio calculations and group theory analysis corroborate the experimental assignments determined by AR-Z-STEM and show that the calculated LF mode fingerprints are related to the 2D crystal symmetries.

Original languageEnglish
Pages (from-to)6333-6342
Number of pages10
JournalACS Nano
Volume9
Issue number6
DOIs
StatePublished - Jun 23 2015

Funding

FundersFunder number
Rensselaer Polytechnic Institute

    Keywords

    • first-principles calculations
    • low-frequency Raman spectroscopy
    • stacking configurations
    • transition metal dichalcogenides
    • two-dimensional materials

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