声子辅助的发光和二维硅碳中的超快激子动力学
Phonon-Assisted Photoluminescence and Ultrafast Exciton Dynamics in Two-Dimensional Silicon Carbide
AI总结：
研究通过全自洽的多体微扰理论分析二维六方硅碳的声子辅助发射和激子动力学，发现高能光学TO LO声子主导侧带形成，并揭示了单层SiC在宽禁带二维半导体中的高效声子辅助发光平台。
摘要：
声子辅助发光为低维半导体中激子声子相互作用提供了直接窗口。利用完全的从头算多体微扰理论，包括有限动量贝叶斯-萨尔佩特计算，我们研究了二维六方硅碳（hSiC）中的声子辅助发射和激子动力学，并将其响应与二维六方氮化硼（hBN）进行基准比较。通过显式解析激子声子矩阵元，我们确定高能光学TO LO声子是侧带形成的主要贡献者，并量化了它们的谱权重。尽管hSiC的激子声子能量分离较小且解析的复制较少，但其声子辅助侧带仍与hBN相当。明亮的KK激子主导近紫外零声子发射，而谷间激子通过对称允许的光学声子耦合获得辐射特性。温度依赖的散射率揭示了在10K时约300fs的明亮激子寿命，突显了由内在声子通道驱动的快速激子弛豫。这些结果确立了单层SiC作为对称激活的高效、无应变声子辅助发光平台，并为宽禁带二维半导体中的超快激子动力学提供了定量框架。
英文摘要：
Phonon assisted photoluminescence provides a direct window into exciton phonon interactions in semiconductors. Using fully ab initio many-body perturbation theory, including finite momentum Bethe Salpeter calculations, we investigate phonon-assisted emission and exciton dynamics in two dimensional (2D) hexagonal silicon carbide (hSiC) and benchmark its response against 2D h boron nitride (hBN). By explicitly resolving exciton phonon matrix elements, we identify an electron-phonon scattering channel mediated by A$^\prime$ high energy longitudinal and transverse optical phonons as the dominant contributors to sideband formation and quantify their spectral weights. We find that h SiC exhibits pronounced phonon-assisted sidebands comparable to hBN, despite a smaller exciton phonon energy separation and fewer resolved replicas. The bright \textbf{K}\textbf{K} exciton governs near UV zero phonon emission, while intervalley excitons acquire radiative character through symmetry allowed optical phonon coupling. Temperature dependent scattering rates reveal an ultrashort bright exciton lifetime of approximately 300 fs at 10 K, highlighting rapid exciton relaxation driven by intrinsic phonon channels.
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