论文标题
Janus过渡金属二甲基元素单层WSSE和MOSSE的拉曼光谱
Raman spectrum of Janus transition metal dichalcogenide monolayers WSSe and MoSSe
论文作者
论文摘要
Janus过渡金属二分法（TMDS）失去了普通TMD的水平镜像对称性，导致出现其他特征，例如天然压电，RashBA效应和增强的催化活性。虽然拉曼光谱法是监测材料合成的必不可少，相位和组成敏感的工具，但仍缺少对Janus单层拉曼光谱的全面研究。在这里，我们讨论了在靠近共鸣的房间和低温温度下测量的WSSE和MOSSE的拉曼光谱。通过将极化分辨的拉曼数据与声子分散体的计算结合并使用对称考虑因素，我们确定了四种一阶拉曼模式和高阶两阶段模式。此外，我们观察到缺陷激活的声子过程，该过程为缺陷浓度进行定量评估提供了途径，从而提供了合成的材料的晶体质量。我们的工作为janus TMD单层的材料合成，研究和应用的未来研究建立了坚实的背景。
Janus transition metal dichalcogenides (TMDs) lose the horizontal mirror symmetry of ordinary TMDs, leading to the emergence of additional features, such as native piezoelectricity, Rashba effect, and enhanced catalytic activity. While Raman spectroscopy is an essential nondestructive, phase- and composition-sensitive tool to monitor the synthesis of materials, a comprehensive study of the Raman spectrum of Janus monolayers is still missing. Here, we discuss the Raman spectra of WSSe and MoSSe measured at room and cryogenic temperatures, near and off resonance. By combining polarization-resolved Raman data with calculations of the phonon dispersion and using symmetry considerations, we identify the four first-order Raman modes and higher-order two-phonon modes. Moreover, we observe defect-activated phonon processes, which provide a route toward a quantitative assessment of the defect concentration and, thus, the crystal quality of the materials synthesized. Our work establishes a solid background for future research on material synthesis, study, and application of Janus TMD monolayers.
