$6H$ $\{0001\}$表面末端的相对稳定性和通过Si蒸发形成石墨烯覆盖层
Relative stability of $6H$-SiC$\{0001\}$ surface terminations and formation of graphene overlayers by Si evaporation
摘要：
我们提出了密度泛函理论（DFT）计算6 H-SiC $\{0001\}$表面与不同的表面堆叠和终端。我们比较了不同的$(0001)$和$(000\bar1)$表面的表面自由能的相对稳定性。去除表面和亚表面的硅原子，我们模拟的石墨烯和石墨烯类覆盖层的形成硅蒸发。我们发现，具有不同性质的键合的覆盖层是优选的在两个非等效的表面取向。在$(0001)$，化学键合，高度应变和屈曲的膜被预测。在$(000\bar1)$中，优选范德华（vdW）键合的覆盖层。我们量化的vdW绑定，并表明它可以有一个掺杂效应的电子行为的覆盖层。
英文摘要：
We present density functional theory (DFT) calculations for 6H-SiC$\{0001\}$ surfaces with different surface stackings and terminations. We compare the relative stability of different $(0001)$ and $(000\bar1)$ surfaces in terms of their surface free energies. Removing surface and subsurface Si atoms, we simulate the formation of graphene and graphene-like overlayers by Si evaporation. We find that overlayers with a different nature of bonding are preferred at the two non-equivalent surface orientations. At $(0001)$, a chemically bonded, highly strained and buckled film is predicted. At $(000\bar1)$, a van der Waals (vdW) bonded overlayer is preferred. We quantify the vdW binding and show that it can have a doping effect on electron behavior in the overlayer.
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