Strain Engineering and Raman Spectroscopy of Monolayer Transition Metal Dichalcogenides
Strain Engineering and Raman Spectroscopy of Monolayer Transition Metal Dichalcogenides
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DOI：
10.1021/acs.chemmater.8b01672
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发表时间：
2018-08-14
影响因子：
8.6
通讯作者：
Pasupathy, A. N.
中科院分区：
文献类型：
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作者：
Dadgar, A. M.;Scullion, D.;Pasupathy, A. N.
我们描述了一种基于聚合物包封的简单技术，将百分之几（>5%）的可控应变施加到单层和少层过渡金属二硫属化物（TMD）上。我们使用这种技术来研究晶格响应应变通过偏振拉曼光谱在单层WSe 2和WS 2。应变的应用导致模式相关的红移，与较大的移位率观察面内模式。我们观察到分裂的平面E'模式的简并在这两种材料和测量的Gruneisen参数。在大应变下，我们观察到晶体对称性的降低可以导致WS 2中A'模式的偏振响应的变化。虽然WSe 2和WS 2的声子结构随着应变表现出类似的定性变化，但我们观察到WS 2的模式位置和强度随着应变发生更大的变化。这些差异可以简单地用金属-硫属元素键的象似性程度来解释。
We describe a facile technique based on polymer encapsulation to apply several percent (>5%) controllable strains to monolayer and few-layer transition metal dichalcogenides (TMDs). We use this technique to study the lattice response to strain via polarized Raman spectroscopy in monolayer WSe2 and WS2. The application of strain causes mode-dependent red shifts, with larger shift rates observed for in-plane modes. We observe a splitting of the degeneracy of the in-plane E' modes in both materials and measure the Gruneisen parameters. At large strain, we observe that the reduction of crystal symmetry can lead to a change in the polarization response of the A' mode in WS2. While both WSe2 and WS2 exhibit similar qualitative changes in the phonon structure with strain, we observe much larger changes in mode positions and intensities with strain in WS2. These differences can be explained simply by the degree of iconicity of the metal-chalcogen bond.