AI 中文总结
本研究通过EELS和从头计算揭示SiC上外延石墨烯缓冲层中四分之一碳原子与硅成键诱导sp³杂化，淬灭π态并破坏对称性，为低能耗晶体管界面设计提供定量基础。
AI 中文摘要
在碳化硅（SiC）界面上生长的外延石墨烯一直是大量研究工作的焦点，这些研究旨在控制其电子输运性质，以推动石墨烯电子器件的应用。本文利用像差校正扫描透射电子显微镜（STEM）中的单色电子能量损失谱（EELS），在原子尺度上研究了SiC(0001)上外延石墨烯缓冲层的电子结构。C K边展现出与独立石墨烯层截然不同的精细谱结构，为键合环境的改变提供了直接实验证据。从头计算提供了位点分辨的轨道特征探针，以阐明这些谱特征的起源：缓冲层中四分之一的碳原子与衬底硅原子之间的共价键合诱导了部分sp³杂化，淬灭了面外π态并破坏了界面层的π共轭。衬底强加的对称性破缺进一步解除了面内轨道的简并性。这一基于π态淬灭和位点特异性对称性破缺的轨道工程框架，为定制石墨烯-衬底界面以应用于下一代低能耗晶体管奠定了定量基础。
英文摘要
The epitaxial graphene grown on SiC interface has been the subject of tremendous research efforts to control its electronic transport properties in the quest for graphene electronic applications. The electronic structure of the epitaxial graphene buffer layer on SiC(0001) is investigated at the atomic scale using monochromated electron energy loss spectroscopy (EELS) in an aberration-corrected scanning transmission electron microscope (STEM). The C $K$-edge reveals spectral fine structures distinctly different from free-standing graphene layer, providing direct experimental evidence of a modified bonding environment. Ab initio calculations providing a site-resolved probe of orbital character to elucidate the origin of these spectral features: covalent bonding between one-quarter of the buffer-layer carbon atoms and the substrate silicon atoms induces partial $\mathrm{sp}^3$ hybridization, quenching the out-of-plane $π$ states and disrupting $π$-conjugation across the interfacial layer. Substrate-imposed symmetry breaking further lifts the in-plane orbital degeneracy. This orbital-engineering framework, rooted in $π$-state quenching and site-specific symmetry breaking, establishes a quantitative basis for tailoring graphene-substrate interfaces toward next-generation low-energy transistor applications.
Comments23 pages (main text), 3 main figures; includes Supporting Information
