Facile and quantitative estimation of strain in nanobubbles with arbitrary symmetry in 2D semiconductors verified using hyperspectral nano-optical imaging
Facile and quantitative estimation of strain in nanobubbles with arbitrary symmetry in 2D semiconductors verified using hyperspectral nano-optical imaging
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DOI：
10.1063/5.0012817
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发表时间：
2020-07-14
影响因子：
4.4
通讯作者：
Schuck, P. James
中科院分区：
文献类型：
--
作者：
Darlington, Thomas P.;Krayev, Andrey;Schuck, P. James
当通过剥离或粘弹性冲压沉积多层范德华材料时，有时会从聚集的捕获流体中产生纳米气泡。尽管纳米气泡可以被认为是一种麻烦，但它们本身就吸引了科学兴趣，因为它们能够产生巨大的面内应变梯度，导致丰富的光电现象，特别是在半导体过渡金属二卤化物中。测定纳米气泡内的应变是理解这些效应的关键，可以用弹性理论来近似。然而，描述变形薄板中应变的Foppl-von Karman方程是高度非线性的，通常需要假设圆对称才能获得解析解。在这里，我们提出了一种易于实现的数值方法来求解二维晶体中任意对称的纳米气泡的应变张量。该方法只需要原子力显微镜的地形信息和二维材料的泊松比。我们验证了这种方法重现了具有已知解析解的圆对称纳米气泡的应变。最后，我们用该方法对模板剥离的Au上的1L-WS2纳米气泡的E‘模的Gruneisen参数进行了重现，将所得应变与尖端增强拉曼光谱测量的拉曼位移进行了比较，证明了该方法用于估算二维晶体中局域应变的有效性。由AIP出版公司授权出版。
When layers of van der Waals materials are deposited via exfoliation or viscoelastic stamping, nanobubbles are sometimes created from aggregated trapped fluids. Though they can be considered a nuisance, nanobubbles have attracted scientific interest in their own right owing to their ability to generate large in-plane strain gradients that lead to rich optoelectronic phenomena, especially in the semiconducting transition metal dichalcogenides. Determination of the strain within the nanobubbles, which is crucial to understanding these effects, can be approximated using elasticity theory. However, the Foppl-von Karman equations that describe strain in a distorted thin plate are highly nonlinear and often necessitate assuming circular symmetry to achieve an analytical solution. Here, we present an easily implemented numerical method to solve for strain tensors of nanobubbles with arbitrary symmetry in 2D crystals. The method only requires topographic information from atomic force microscopy and the Poisson ratio of the 2D material. We verify that this method reproduces the strain for circularly symmetric nanobubbles that have known analytical solutions. Finally, we use the method to reproduce the Gruneisen parameter of the E ' mode for 1L-WS2 nanobubbles on template-stripped Au by comparing the derived strain with measured Raman shifts from tip-enhanced Raman spectroscopy, demonstrating the utility of our method for estimating localized strain in 2D crystals. Published under license by AIP Publishing.