过渡金属二硫族化物单层中共振拉曼谱的理论：谷间声子散射引起的干涉效应
Theory of resonance Raman profiles in transition metal dichalcogenide monolayers: Interference effects due to inter-valley phonon scattering
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- University of Münster（明斯特大学）
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中文总结 AI 辅助
本文通过微观模型研究单层TMDCs中谷间散射和应变对共振拉曼散射的影响，发现WSe₂中K-Q谷间散射导致一阶与三阶拉曼过程相消干涉，抑制入射共振，与实验一致。
中文摘要 AI 辅助
单层过渡金属二硫族化物（TMDCs）的光学性质受到激子-声子耦合的强烈影响，尤其是在钨基材料中，谷间散射尤为显著。结合K-Q谷间能量分离的应变可调性，这类材料为半导体光力学提供了一个平台。本文利用基于有效形变势耦合的微观模型描述激子-声子相互作用，研究了单层TMDCs中谷间散射和应变对共振拉曼散射的影响。以hBN封装的单层WSe$_2$中A$_1$模式的共振拉曼谱为例，我们发现电子K谷和Q谷之间的谷间散射会导致一阶和三阶拉曼过程之间的相消干涉。因此，我们得到了WSe$_2$中入射共振的抑制，这与最近发表的实验数据一致。
英文摘要
The optical properties of monolayer transition metal dichalcogenides (TMDCs) are strongly impacted by exciton-phonon coupling, especially inter-valley scattering in the case of tungsten-based materials. Together with strain-tunability of the energetic K-Q valley separation this material class therefore provides a platform for semiconductor optomechanics. Here we investigate the influence of inter-valley scattering and strain on resonance Raman scattering in monolayer TMDCs using a microscopic model based on an effective deformation potential coupling for the exciton-phonon interaction. Considering exemplarily the resonance Raman profile of the A$_1$-mode in hBN-encapsulated monolayer WSe$_2$, we find that inter-valley scattering between the electronic K- and Q-valley leads to destructive interference between a first order and a third order Raman process. As a result we obtain a suppression of the incoming resonance in WSe$_2$, consistent with recently published experimental data.
