Interlayer breathing and shear modes in few-trilayer MoS2 and WSe2.
By Yanyuan Zhao, Xin Luo, Hai Li, Jun Zhang, P. T. Araujo, C. Gan, Jumiati Wu, Hua Zhang, S. Y. Quek, Mildred S. Dresselhaus and 1 more. Nano letters (Print), 2013
638 citations recorded by the source corpus.
Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have recently attracted tremendous interest as potential valleytronic and nanoelectronic materials, in addition to being well-known as excellent lubricants in the bulk. The interlayer van der Waals (vdW) coupling and low-frequency phonon modes and how they evolve with the number of layers are important for both the mechanical and the electrical properties of 2D TMDs. Here we uncover the ultralow frequency interlayer breathing and shear modes in few-layer MoS2 and WSe2, prototypical layered TMDs, using both Raman spectroscopy and first principles calculations. Remarkably, the frequencies of these modes can be perfectly described using a simple linear chain model with only nearest-neighbor interactions. We show that the derived in-plane (shear) and out-of-plane (breathing) force constants from experiment remain the same from two-layer 2D crystals to the bulk materials, suggesting that the nanoscale interlayer frictional characteristics of these excellent lubricants should be independent of the number of layers.
Subfields: Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/7bcd661ecef632c5b4810a4b02f209142520715c
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Citations in the corpus
- Raman Techniques: Fundamentals and Frontiers (2019, methodology): “ing and shear modes [19], in-plane anisotropy [20], doping [21–23], disorder [10, 24–26], thermal conductivity [11], strain [27] and phonon modes [14, 16, 28] can be extracted using Raman spectroscopy.”
- Few-layer MoS2: a promising layered semiconductor. (2014, background): “There also exist low-frequency interlayer breathing (B2g (2)) and shear (E2g (2)) modes (see Figure 2b,d,e), which are functions of the layer number and can be used to examine the structural properties of few-layer MoS2 flakes and determine layer number.(65,75,76) The shear mode E2g 2 is found to un”
- Interlayer interactions in anisotropic atomically thin rhenium diselenide (2015, background): “2 cm–1, respectively [38], which are higher than those in bilayer ReSe2.”