Formation of graphene atop a Si adlayer on the C-face of SiC
Formation of graphene atop a Si adlayer on the C-face of SiC
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DOI：
10.1103/physrevmaterials.3.084006
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发表时间：
2019-05
影响因子：
3.4
通讯作者：
Jun Li;Qingxiao Wang;Guowei He;M. Widom;L. Nemec;V. Blum;Moon J. Kim;P. Rinke;R. Feenstra
中科院分区：
文献类型：
--
作者：
Jun Li;Qingxiao Wang;Guowei He;M. Widom;L. Nemec;V. Blum;Moon J. Kim;P. Rinke;R. Feenstra
研究了在二硅烷(Si2H6)气体环境中，碳化硅(000-1)表面的结构，即{0001}碳化硅表面的C面结构随温度和压力的变化关系。在有或没有覆盖石墨烯层(在足够高的温度下自发形成)的情况下，观察到了各种表面重建。基于横截面扫描电子显微镜测量，发现在石墨烯存在下形成的界面结构包含1.4-1.7个单分子层(ML)的硅，这在一定程度上是一个有悖于直觉的结果，因为当石墨烯形成时，体系实际上处于富碳条件下。用从头算热力学方法证明了存在一类富硅表面，它含有约1.3ML的硅，在400K以上的温度下(即使在富C条件下)也是稳定的。这样形成的结构是由硅原子在碳化硅C面上的硅附着层上形成的，无论有没有覆盖石墨烯的存在。
The structure of the SiC(000-1) surface, the C-face of the {0001} SiC surfaces, is studied as a function of temperature and of pressure in a gaseous environment of disilane (Si2H6). Various surface reconstructions are observed, both with and without the presence of an overlying graphene layer (which spontaneously forms at sufficiently high temperatures). Based on cross-sectional scanning transmission electron microscopy measurements, the interface structure that forms in the presence of the graphene is found to contain 1.4 - 1.7 monolayers (ML) of Si, a somewhat counter-intuitive result since, when the graphene forms, the system is actually under C-rich conditions. Using ab initio thermodynamics, it is demonstrated that there exists a class of Si-rich surfaces containing about 1.3 ML of Si that are stable on the surface (even under C-rich conditions) at temperatures above about 400 K. The structures that thus form consist of Si adatoms atop a Si adlayer on the C-face of SiC, with or without the presence of overlying graphene.