A deep grasp of the properties of the interface between organic molecules and hexagonal boron nitride (h-BN) is essential for the full implementation of these two building blocks in the next generation of electronic devices. Here, using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), we report on the geometric and electronic features of C60 evaporated on a single layer of h-BN grown on a Rh(110) surface under ultra-high vacuum. Two different molecular assemblies of C60 on the h-BN/Rh(110) surface were observed. The first STM study at room temperature (RT) and at low temperatures (40 K) looked at the molecular orientation of C60 on a two-dimensional layered material. Intramolecular-resolution images demonstrate the existence of a phase transition of C60 over the h-BN/Rh(110) surface similar to that found on bulk solid C60. At RT molecules exhibit random orientations, while at 40 K such rotational disorder vanishes and they adopt a common orientation over the h-BN/Rh(110) surface. The decrease in thermal energy allows recognition between C60 molecules, and they become equally oriented in the configuration at which the van der Waals intermolecular interactions are optimized. Bias-dependent submolecular features obtained by means of high-resolution STM images are interpreted as the highest occupied and lowest unoccupied molecular orbitals. STS data showed that fullerenes are electronically decoupled from the substrate, with a negligible charge transfer effect if any. Finally, the very early stages of multilayer growth were also investigated.

中文翻译：

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分子间耦合诱导的 h-BN 上的 C60 自取向


深入掌握有机分子和六方氮化硼 (h-BN) 之间的界面特性对于在下一代电子设备中全面实现这两个构建模块至关重要。在这里，我们使用扫描隧道显微镜（STM）和扫描隧道光谱（STS），报告了超高真空下在Rh（110）表面上生长的单层h-BN上蒸发的C60的几何和电子特征。观察到 h-BN/Rh(110) 表面上两种不同的 C60 分子组装体。室温 (RT) 和低温 (40 K) 下的第一项 STM 研究着眼于二维层状材料上 C60 的分子取向。分子内分辨率图像表明 C60 在 h-BN/Rh(110) 表面上存在相变，类似于块状固体 C60 上的相变。在 RT 下，分子表现出随机方向，而在 40 K 下，这种旋转无序消失，并且它们在 h-BN/Rh(110) 表面上采用共同方向。热能的降低使得 C60 分子之间能够相互识别，并且它们在构型中变得相同取向，在该构型中范​​德华分子间相互作用得到优化。通过高分辨率 STM 图像获得的偏倚相关亚分子特征被解释为最高占据和最低未占据分子轨道。 STS 数据表明，富勒烯与基底发生电子解耦，电荷转移效应（如果有的话）可以忽略不计。最后，还研究了多层生长的早期阶段。