Bandgap Engineering of Strained Monolayer and Bilayer MoS2
Bandgap Engineering of Strained Monolayer and Bilayer MoS2
复制标题
DOI：
10.1021/nl4014748
复制
发表时间：
2013-08-01
期刊：
影响因子：
10.8
通讯作者：
Bolotin, Kirill I.
中科院分区：
文献类型：
--
作者：
Conley, Hiram J.;Wang, Bin;Bolotin, Kirill I.
本文报道了在0-2.2%范围内的单轴拉伸机械应变对单层和双层二硫化钼（MoS 2）二维晶体的声子谱和能带结构的影响。首先，我们采用拉曼光谱观察声子软化与应变增加，打破了在E'拉曼模式的二硫化钼的简并，并提取一个Gruneisen参数类似于1.06。第二，使用光致发光光谱，我们测量的光学带隙的MoS 2，这是近似线性的应变，类似于45毫电子伏/%的应变单层MoS 2和类似于120毫电子伏/%的应变双层MoS 2的减少。第三，我们观察到一个显着的应变引起的单层二硫化钼的光致发光强度的下降，这是指示的直接到间接的过渡的这种材料的光学带隙的字符在施加的应变类似于1%。这些观察构成了应变工程的带结构的新兴类的二维晶体，过渡金属二硫属化物的演示。
We report the influence of uniaxial tensile mechanical strain in the range 0-2.2% on the phonon spectra and bandstructures of monolayer and bilayer molybdenum disulfide (MoS2) two-dimensional crystals. First, we employ Raman spectroscopy to observe phonon softening with increased strain, breaking the degeneracy in the E' Raman mode of MoS2, and extract a Gruneisen parameter of similar to 1.06. Second, using photoluminescence spectroscopy we measure a decrease in the optical band gap of MoS2 that is approximately linear with strain, similar to 45 meV/% strain for monolayer MoS2 and similar to 120 meV/% strain for bilayer MoS2. Third, we observe a pronounced strain-induced decrease in the photoluminescence intensity of monolayer MoS2 that is indicative of the direct-to-indirect transition of the character of the optical band gap of this material at applied strain of similar to 1%. These observations constitute a demonstration of strain engineering the band structure in the emergent class of two-dimensional crystals, transition-metal dichalcogenides.