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Extraordinary Phonon Displacement and Giant Resonance Raman Enhancement in WSe2/WS2 Moiré Heterostructures
ACS Nano ( IF 15.8 ) Pub Date : 2022-11-28 , DOI: 10.1021/acsnano.2c10092 Sharidya Rahman 1 , Xueqian Sun 1 , Yi Zhu 2 , Yuerui Lu 1, 3
ACS Nano ( IF 15.8 ) Pub Date : 2022-11-28 , DOI: 10.1021/acsnano.2c10092 Sharidya Rahman 1 , Xueqian Sun 1 , Yi Zhu 2 , Yuerui Lu 1, 3
Affiliation
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Twisted van der Waals heterostructures are known to induce surprisingly diverse and intriguing phenomena, such as correlated electronic phase and unconventional optical properties. This can be realized by controlled rotation of adjacent atomic planes, which provides an uncommon way to manipulate inelastic light–matter interactions. Here, we discover an extraordinary blue shift of 5–6 wavenumbers for high-frequency phonon modes in WS2/WSe2 twisted heterobilayers, captured meticulously using Raman spectroscopy. Phonon spectra displace rapidly over a subtle change in interlayer twist angle owing to heterostrain and atomic reconstruction from the Moiré pattern. First-order linear coefficients of the phonon modes in twisted heterostructures are further found to increase largely compared to their monolayer counterpart and vary immensely with the twist angle. Exceptional and extravagant enhancement of up to 50-fold is observed in the Raman vibrational intensity at a specific twist angle; this is largely influenced by the resonance process derived from a simple critical twist angle model. In addition, we depict how the resonance can be modulated by changing the thermal conditions and also the stacking angle. Therefore, our work further highlights the twist-driven phonon dynamics in pristine two-dimensional heterostructures, adding vital insight into Moiré physics and promoting comprehensive understanding of structural and optical properties in Moiré superlattices.
中文翻译：
WSe2/WS2 莫尔异质结构中的非凡声子位移和巨共振拉曼增强
众所周知，扭曲的范德瓦尔斯异质结构会引起令人惊讶的多样化和有趣的现象，例如相关的电子相位和非常规的光学特性。这可以通过相邻原子平面的受控旋转来实现，这提供了一种不常见的方式来操纵非弹性光-物质相互作用。在这里，我们发现 WS 2 /WSe 2中高频声子模式的 5-6 波数的异常蓝移扭曲的异质双分子层，使用拉曼光谱精心捕获。由于莫尔图案的异质应变和原子重建，声子光谱在层间扭曲角的细微变化上迅速发生位移。进一步发现，与单层对应物相比，扭曲异质结构中声子模式的一阶线性系数大幅增加，并且随扭曲角变化很大。在特定扭转角的拉曼振动强度中观察到高达 50 倍的异常和过度增强；这在很大程度上受到源自简单临界扭转角模型的共振过程的影响。此外，我们描述了如何通过改变热条件和堆叠角度来调制共振。所以，
更新日期：2022-11-28
中文翻译：
WSe2/WS2 莫尔异质结构中的非凡声子位移和巨共振拉曼增强
众所周知，扭曲的范德瓦尔斯异质结构会引起令人惊讶的多样化和有趣的现象，例如相关的电子相位和非常规的光学特性。这可以通过相邻原子平面的受控旋转来实现，这提供了一种不常见的方式来操纵非弹性光-物质相互作用。在这里，我们发现 WS 2 /WSe 2中高频声子模式的 5-6 波数的异常蓝移扭曲的异质双分子层，使用拉曼光谱精心捕获。由于莫尔图案的异质应变和原子重建，声子光谱在层间扭曲角的细微变化上迅速发生位移。进一步发现，与单层对应物相比，扭曲异质结构中声子模式的一阶线性系数大幅增加，并且随扭曲角变化很大。在特定扭转角的拉曼振动强度中观察到高达 50 倍的异常和过度增强；这在很大程度上受到源自简单临界扭转角模型的共振过程的影响。此外，我们描述了如何通过改变热条件和堆叠角度来调制共振。所以，
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