Measurement of local optomechanical properties of a direct bandgap 2D semiconductor
Measurement of local optomechanical properties of a direct bandgap 2D semiconductor
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DOI：
10.1063/1.5117259
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发表时间：
2019-10-01
期刊：
影响因子：
6.1
通讯作者：
Iorsh, I. V.
中科院分区：
文献类型：
--
作者：
Benimetskiy, F. A.;Sharov, V. A.;Iorsh, I. V.
应变工程是调节二维材料物理特性的强大工具，包括具有强激子响应的单层过渡金属二硫属化物 (TMD) 直接带隙半导体。 TMD 单层的变形可以引起激子势的调制，并最终在所需位置产生单光子发射器。此类系统的性能关键取决于激子能量分布和在局部冲击下直到单层破裂为止可以实现的最大可能激子能量转移。在这里，我们研究了在增量局部压痕直至破裂的情况下，MoSe2 单层中诱发的二维激子能量分布的演变。我们用原子力显微镜尖端可控地对薄片施加应力，并对压痕点附近的激子光致发光进行原位空间光谱测绘。为了准确地拟合实验数据，我们将数值模拟与局部激子响应的应变诱导修改的简单模型相结合，并仔细考虑了装置的光学分辨率。这使我们能够提取在每个压痕深度获得的变形、应变和激子能量分布。在 300 nm 压痕处实现的局部变形引起的最大激子能量位移达到 36.5 meV，对应于单层的 1.15% 应变。我们的方法是对具有强激子响应的二维直接带隙半导体的局部光机械特性进行原位表征的强大工具。 (C) 2019 年作者。
Strain engineering is a powerful tool for tuning physical properties of 2D materials, including monolayer transition metal dichalcogenides (TMDs)-direct bandgap semiconductors with strong excitonic response. Deformation of TMD monolayers allows inducing modulation of exciton potential and, ultimately, creating single-photon emitters at desired positions. The performance of such systems is critically dependent on the exciton energy profile and maximum possible exciton energy shift that can be achieved under local impact until the monolayer rupture. Here, we study the evolution of two-dimensional exciton energy profile induced in a MoSe2 monolayer under incremental local indentation until the rupture. We controllably stress the flake with an atomic force microscope tip and perform in situ spatiospectral mapping of the excitonic photoluminescence in the vicinity of the indentation point. In order to accurately fit the experimental data, we combine numerical simulations with a simple model of strain-induced modification of the local excitonic response and carefully account for the optical resolution of the setup. This allows us to extract deformation, strain, and exciton energy profiles obtained at each indentation depth. The maximum exciton energy shift induced by local deformation achieved at 300 nm indentation reaches the value of 36.5 meV and corresponds to 1.15% strain of the monolayer. Our approach is a powerful tool for in situ characterization of local optomechanical properties of 2D direct bandgap semiconductors with strong excitonic response. (C) 2019 Author(s).