Contracted interlayer distance in graphene/sapphire heterostructure
Contracted interlayer distance in graphene/sapphire heterostructure
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DOI：
10.1007/s12274-014-0640-7
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发表时间：
2015-05-01
期刊：
影响因子：
9.9
通讯作者：
Sakai, Seiji
中科院分区：
文献类型：
--
作者：
Entani, Shiro;Antipina, Liubov Yu;Sakai, Seiji
石墨烯在绝缘体上的直接生长有望显著改善石墨烯基电子和自旋电子器件的性能。在这项研究中，我们成功地揭示了单层石墨烯和α-Al 2 O3（0001）的相干异质结构的原子排列和电子性质。对单层石墨烯在α-Al 2 O3（0001）上的原子排列的分析揭示了一个明显的矛盾。平面内分析表明，单层石墨烯生长的单晶外延的方式，而是在多晶的形式，具有两个强烈的明显的优选取向。这表明相对较弱的界面相互作用是有效的。然而，我们证明了石墨烯和α-Al 2 O3（0001）之间存在异常强的物理相互作用，这一点可以通过石墨烯和α-Al 2 O3（0001）表面之间的小间隔来证明。界面相互作用主要是石墨烯π体系中的静电力和α-Al 2 O3（0001）最顶层O层的不饱和电子，而不是货车范德华相互作用。这样的特征导致石墨烯空穴掺杂，并使石墨烯能够在α-Al 2 O3（0001）表面上滑动，尽管界面相互作用很强，但能量势垒很小。
Direct growth of graphene on insulators is expected to yield significant improvements in performance of graphene-based electronic and spintronic devices. In this study, we successfully reveal the atomic arrangement and electronic properties of a coherent heterostructure of single-layer graphene and alpha-Al2O3(0001). The analysis of the atomic arrangement of single-layer graphene on alpha-Al2O3(0001) revealed an apparentcontradiction. The in-plane analysis shows that single-layer graphene grows not in a single-crystalline epitaxial manner, but rather in polycrystalline form, with two strongly pronounced preferred orientations. This suggests relatively weak interfacial interactions are operative. However, we demonstrate that unusually strong physical interactions between graphene and alpha-Al2O3(0001) exist, as evidenced by the small separation between the graphene and the alpha-Al2O3(0001) surface. The interfacial interaction is shown to be dominated by the electrostatic forces involved in the graphene pi-system and the unsaturated electrons of the topmost O layer of alpha-Al2O3(0001), rather than the van der Waals interactions. Such features causes graphene hole doping and enable the graphene to slide on the alpha-Al2O3(0001) surface with only a small energy barrier despite the strong interfacial interactions.