SiC上石墨烯覆盖的铋烯的共振增强拉曼响应
Resonantly-enhanced Raman response in graphene-capped bismuthene on SiC
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中文总结 AI 辅助
该研究针对石墨烯覆盖铋烯封装确认依赖超高真空技术的问题，采用非原位快速拉曼表征，确认铋烯E₂g声子，发现共振增强拉曼响应，确立拉曼显微光谱为探测石墨烯保护量子材料的通用工具。
中文摘要 AI 辅助
基于原子单层的二维量子自旋霍尔绝缘体为无耗散电子学提供了有前景的途径，但其实际应用常受限于环境不稳定性。用石墨烯覆盖层封装该系统已被证实是防止氧化和降解的可靠方法，但成功封装的确认仍依赖超高真空技术，这极大地减缓了流程。本文中，我们对SiC上的铋烯（一种Bi的蜂窝状单层）进行了一种非原位、快速、无损且空间分辨的拉曼表征。通过与密度泛函微扰理论计算对比，在约122 cm⁻¹处观测到的显著拉曼散射峰被确认为铋烯的E₂g声子。我们利用激发能量和偏振依赖的拉曼测量明确归属光谱特征。当将激发能量调至接近原始铋烯的激子跃迁时，我们观测到拉曼响应的强增强及额外散射峰的出现；在此 regime 下，高阶声子特征以及铋烯与SiC衬底之间的界面模式变得可见，表明共振散射过程的参与。我们的研究确立了拉曼显微光谱作为探测石墨烯保护量子材料的通用工具，可用于获取晶格动力学和层间耦合信息。
英文摘要
Two-dimensional quantum spin Hall insulators based on atomic monolayers offer a promising route toward dissipationless electronics, yet their practical use is often limited by environmental instability. Encapsulating the system with a graphene capping layer has been shown to be a reliable method to prevent oxidation and degradation. However, the confirmation of a successful encapsulation still relies on ultra-high vacuum techniques, that considerably slow the process. Here, we present an ex situ, rapid, nondestructive and spatially resolved Raman characterization of graphene-capped bismuthene, a honeycomb monolayer of Bi on SiC. A pronounced Raman scattering peak at around 122 cm-1 is identified as the E2g phonon of bismuthene, via a comparison with density functional perturbation theory calculations. We use excitation-energy and polarization-dependent Raman measurements to enable an unambiguous assignment of the spectral features. Tuning the excitation energy close to the excitonic transition in pristine bismuthene, we observe a strong enhancement of the Raman response and the emergence of additional scattering peaks. In this regime, higher-order phonon features, as well as interfacial modes between bismuthene and the SiC substrate, become visible, suggesting the involvement of resonant scattering processes. Our results establish Raman micro-spectroscopy as a versatile tool for probing graphene-protected quantum materials, providing access to lattice dynamics and interlayer coupling.
