Department of Materials Science and Engineering, University of California, Berkeley, California 94720, United States.
Nano Lett. 2010 Dec 8;10(12):4890-6. doi: 10.1021/nl102788f. Epub 2010 Oct 27.
We have observed the growth of monolayer graphene on Cu foils using low-energy electron microscopy. On the (100)-textured surface of the foils, four-lobed, 4-fold-symmetric islands nucleate and grow. The graphene in each of the four lobes has a different crystallographic alignment with respect to the underlying Cu substrate. These "polycrystalline" islands arise from complex heterogeneous nucleation events at surface imperfections. The shape evolution of the lobes is well explained by an angularly dependent growth velocity. Well-ordered graphene forms only above ∼790 °C. Sublimation-induced motion of Cu steps during growth at this temperature creates a rough surface, where large Cu mounds form under the graphene islands. Strategies for improving the quality of monolayer graphene grown on Cu foils must address these fundamental defect-generating processes.
我们使用低能电子显微镜观察到单层石墨烯在 Cu 箔上的生长。在箔的（100）织构表面上，四叶、四对称的岛开始形核并生长。每个四叶中的石墨烯相对于下面的 Cu 衬底具有不同的晶体取向。这些“多晶”岛是由表面缺陷处的复杂非均匀形核事件引起的。叶瓣的形状演化可以很好地用角相关的生长速度来解释。只有在大约 790°C 以上，才能形成有序的石墨烯。在这个温度下，生长过程中 Cu 台阶的升华诱导运动导致表面粗糙，在石墨烯岛下形成大的 Cu 丘。提高在 Cu 箔上生长的单层石墨烯质量的策略必须解决这些产生缺陷的基本过程。
