Atomic-scale characterization of the interfacial phonon in graphene/SiC
Atomic-scale characterization of the interfacial phonon in graphene/SiC
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DOI：
10.1103/physrevb.96.155431
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发表时间：
2017-10-11
影响因子：
3.7
通讯作者：
Komeda, Tadahiro
中科院分区：
文献类型：
--
作者：
Minamitani, Emi;Arafune, Ryuichi;Komeda, Tadahiro
SiC上的外延石墨烯在绝缘衬底上提供晶片级和高质量的石墨烯片，是实现石墨烯基纳米器件的一种有前途的材料。绝缘衬底的存在通过界面声子改变了独立石墨烯的物理性质，例如，限制了流动性。尽管对材料性能有这样的已知影响，但缺少完整的微观图像。在这里，我们报告原子分辨非弹性电子隧穿光谱（IETS）与扫描隧道显微镜上生长的4 H-SiC（0001）的外延石墨烯。我们的数据揭示了IETS光谱中强烈的空间依赖性，这不能用石墨烯的固有特性来解释。我们表明，这种变化的IETS光谱起源于本地化的低能量振动的界面Si原子与悬挂键通过从头计算电子和声子态计算。这种见解可以通过界面控制帮助推进石墨烯器件性能。
Epitaxial graphene on SiC that provideswafer-scale and high-quality graphene sheets on an insulating substrate is a promising material to realize graphene-based nanodevices. The presence of the insulating substrate changes the physical properties of free-standing graphene through the interfacial phonon, e.g., limiting the mobility. Despite such known impacts on the material properties, a complete and microscopic picture is missing. Here, we report on atomically resolved inelastic electron tunneling spectroscopy (IETS) with a scanning tunneling microscope for epitaxial graphene grown on 4H-SiC(0001). Our data reveal a strong spatial dependence in the IETS spectrum, which cannot be explained by intrinsic graphene properties. We show that this variation in the IETS spectrum originates from a localized low-energy vibration of the interfacial Si atom with a dangling bond via ab initio electronic and phononic state calculations. This insight may help advancing graphene device performance through interfacial control.