The chemical vapor deposition of CH4 on Ge(001) results in the anisotropic synthesis of graphene nanoribbons that are aligned to Ge⟨110⟩ and have faceted armchair edges, sub-10 nm widths, and lengths greater than 100 nm. The utilization of small graphene seeds to initiate nanoribbon synthesis provides control over the nanoribbon placement and orientation. However, in order to exclusively grow nanoribbons and suppress the concomitant growth of lower aspect ratio crystals, it is imperative to control the crystallographic orientation of the seeds with respect to the Ge lattice. Here, we demonstrate that when seeds are less than 18 nm in diameter, they are able to rotate upon annealing at 910 °C prior to nanoribbon synthesis. The effect of this rotation on the resulting nanoribbons’ orientation is characterized as a function of the diameter and initial crystallographic orientation of the seeds. The seeds preferentially rotate to an orientation in which an armchair direction of their lattice is parallel to Ge⟨110⟩—subsequently maximizing the anisotropy in growth kinetics. By exploiting this seed rotation phenomenon, we demonstrate the fabrication of seamless nanoribbon meshes and gain understanding that will affect future efforts to create arrays of unidirectionally aligned nanoribbons.

中文翻译：

---

用于通过化学气相沉积在 Ge(001) 上合成纳米带的石墨烯种子的旋转自对准

CH4 在 Ge(001) 上的化学气相沉积导致石墨烯纳米带的各向异性合成，石墨烯纳米带与 Ge⟨110⟩ 对齐，并具有多面的扶手椅边缘，宽度低于 10 nm，长度大于 100 nm。利用小石墨烯种子启动纳米带合成提供了对纳米带放置和取向的控制。然而，为了专门生长纳米带并抑制低纵横比晶体的伴随生长，必须控制种子相对于 Ge 晶格的晶体取向。在这里，我们证明当种子直径小于 18 nm 时，它们能够在纳米带合成之前在 910 °C 退火时旋转。这种旋转对所得纳米带取向的影响被表征为种子直径和初始结晶取向的函数。种子优先旋转到其晶格的扶手椅方向平行于 Ge⟨110⟩ 的方向 - 随后最大化生长动力学的各向异性。通过利用这种种子旋转现象，我们展示了无缝纳米带网格的制造，并获得了理解，这将影响未来创建单向对齐纳米带阵列的努力。