II. Physikalisches Institut, Universität zu Köln , Zülpicher Straße 77, 50937 Köln, Germany.
Institut für Materialphysik, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Straße 10, 48149 Münster, Germany.
ACS Nano. 2016 Dec 27;10(12):11012-11026. doi: 10.1021/acsnano.6b05819. Epub 2016 Nov 21.
Using the X-ray standing wave method, scanning tunneling microscopy, low energy electron diffraction, and density functional theory, we precisely determine the lateral and vertical structure of hexagonal boron nitride on Ir(111). The moiré superstructure leads to a periodic arrangement of strongly chemisorbed valleys in an otherwise rather flat, weakly physisorbed plane. The best commensurate approximation of the moiré unit cell is (12 × 12) boron nitride cells resting on (11 × 11) substrate cells, which is at variance with several earlier studies. We uncover the existence of two fundamentally different mechanisms of layer formation for hexagonal boron nitride, namely, nucleation and growth as opposed to network formation without nucleation. The different pathways are linked to different distributions of rotational domains, and the latter enables selection of a single orientation only.
使用 X 射线驻波法、扫描隧道显微镜、低能电子衍射和密度泛函理论，我们精确地确定了六方氮化硼在 Ir(111)上的横向和纵向结构。莫尔超晶格导致了强烈化学吸附谷的周期性排列，而在原本较为平坦、弱物理吸附的平面上则形成了莫尔超晶格。莫尔单元的最佳准共形近似是（12×12）氮化硼单元位于（11×11）衬底单元上，这与之前的几项研究不同。我们揭示了六方氮化硼形成层的两种根本不同的机制，即成核和生长，而不是没有成核的网络形成。不同的途径与旋转畴的不同分布有关，而后者仅能选择单一的取向。
