Laboratoire Charles Coulomb, UMR5221 CNRS-Université Montpellier II, Place Eugène Bataillon - cc074, 34095 Montpellier Cedex 5, France.
Nanoscale Res Lett. 2011 Jul 29;6(1):478. doi: 10.1186/1556-276X-6-478.
Micro-Raman and micro-transmission imaging experiments have been done on epitaxial graphene grown on the C- and Si-faces of on-axis 6H-SiC substrates. On the C-face it is shown that the SiC sublimation process results in the growth of long and isolated graphene ribbons (up to 600 μm) that are strain-relaxed and lightly p-type doped. In this case, combining the results of micro-Raman spectroscopy with micro-transmission measurements, we were able to ascertain that uniform monolayer ribbons were grown and found also Bernal stacked and misoriented bilayer ribbons. On the Si-face, the situation is completely different. A full graphene coverage of the SiC surface is achieved but anisotropic growth still occurs, because of the step-bunched SiC surface reconstruction. While in the middle of reconstructed terraces thin graphene stacks (up to 5 layers) are grown, thicker graphene stripes appear at step edges. In both the cases, the strong interaction between the graphene layers and the underlying SiC substrate induces a high compressive thermal strain and n-type doping.
已经在 C 面和 Si 面上的晶轴 6H-SiC 衬底上生长的外延石墨烯上进行了微拉曼和微传输成像实验。在 C 面上，SiC 的升华过程导致长而孤立的石墨烯带（长达 600μm）的生长，这些石墨烯带是应变弛豫的，并且轻度 p 型掺杂。在这种情况下，通过将微拉曼光谱的结果与微传输测量相结合，我们能够确定生长了均匀的单层带，并且还发现了伯纳尔堆叠和取向不同的双层带。在 Si 面上，情况则完全不同。尽管 SiC 表面的重构导致各向异性生长，但仍实现了 SiC 表面的完全石墨烯覆盖。在重构平台的中间生长了很薄的石墨烯层（多达 5 层），而在台阶边缘则出现了较厚的石墨烯条纹。在这两种情况下，石墨烯层与下面的 SiC 衬底之间的强烈相互作用会导致高压缩热应变和 n 型掺杂。
