Interface-Mediated Resonant Raman Enhancement for Shear Modes in a 2D Polar Metal
Interface-Mediated Resonant Raman Enhancement for Shear Modes in a 2D Polar Metal
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DOI：
10.1021/acs.jpcc.2c04433
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Wen-Yu He;Maxwell T. Wetherington;K. Ulman;J. Robinson;S. Y. Quek
中科院分区：
文献类型：
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作者：
Wen-Yu He;Maxwell T. Wetherington;K. Ulman;J. Robinson;S. Y. Quek
通过限制异质外延在SiC/石墨烯界面处合成的2D极性金属共价结合到SiC衬底。在这项工作中，我们阐明了SiC衬底的重要性，特别是Ga/Si界面上的低频共振拉曼光谱的二维镓SiC。在二维Ga中，低频拉曼模主要是面内剪切模。我们表明，这些剪切模式的频率被修改的存在下，基板的几层Ga和这些剪切模式强烈耦合到对应于界面Ga和Si原子的电子态。因此，共振拉曼增强发生在与涉及这些界面Ga和Si状态的带间光学跃迁共振的激光入射能量处。这种共振拉曼增强是在激光能量依赖的测量中观察到的，这是这些2D极性金属中存在的强电子-声子耦合的实验特征。
2D polar metals synthesized by confinement heteroepitaxy at the SiC/graphene interface are covalently bound to the SiC substrate. In this work, we elucidate the importance of the SiC substrate, and specifically the Ga/Si interface, on the low-frequency resonant Raman spectra of 2D Ga on SiC. The low-frequency Raman modes are dominated by in-plane shear modes in 2D Ga. We show that the frequency of these shear modes is modified by the presence of the substrate for few-layer Ga and that these shear modes couple strongly to the electronic states corresponding to the interface Ga and Si atoms. Consequently, resonant Raman enhancement occurs at laser incident energies that are resonant with the interband optical transitions involving these interface Ga and Si states. This resonant Raman enhancement is observed in laser-energy-dependent measurements, an experimental signature of the strong electron–phonon coupling present in these 2D polar metals.