Two-dimensional (2D) transition metal dichalcogenides (TMDs) offer unique optoelectronic capabilities due to their direct bandgap semiconductor nature in monolayer form. Atomically thin TMDs can be assembled in vertical stacks that are held together by van der Waals forces, enabling interlayer coupling between the layers. This creates new physical properties that depend on the relative orientation (twist angle) between the TMD monolayers. Accurate and fast measurement of the twist angle is therefore of utmost importance for characterizing a 2D TMD heterostructure. Here, we present a nonlinear imaging technique based on second harmonic generation (SHG) microscopy, that enables instantaneous mapping of the twist angle between the two stacked TMD monolayers. By using a polarization beam splitter in the detection path and two detectors measuring two orthogonal SHG polarization components, we acquire with a single-shot measurement the twist angle in a WS 2 /MoS 2 h...

中文翻译：

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过渡金属二卤化物异质双分子层扭曲角的实时空间分辨测定

二维（2D）过渡金属二硫化碳（TMD）由于具有单层形式的直接带隙半导体性质而具有独特的光电功能。原子薄的TMD可以组装成垂直堆叠，并通过范德华力保持在一起，从而实现层之间的层间耦合。这将创建新的物理属性，该属性取决于TMD单层之间的相对方向（扭转角）。因此，准确，快速地测量扭转角对于表征2D TMD异质结构至关重要。在这里，我们提出了一种基于二次谐波生成（SHG）显微镜的非线性成像技术，该技术能够即时映射两个堆叠的TMD单层之间的扭曲角。