石墨烯/六方氮化硼面内拼接超晶格结构的可控制备及物性研究

Graphene nanoribbons (GNRs), the quasi-one-dimensional strips of graphene, have attracted tremendous attention, due to their tunable band gap, which is crucial for future graphene-base electronics. Here, we propose to synthesize in-plane graphene-hexagnoal boron nitride (G-hBN) superlattice, which is expected to fulfill the requirements of both band structure engineering of graphene and scalable device fabrication. We plan to prepare in-plane G-hBN superlattice via a two-step “bottom-up” approach. In a first step, the precursor molecules of graphene will react with each other and form GNRs after deposition on clean high-index metal single-crystal surface and with sample heating in ultrahigh vacuum. These GNRs are expected to locate at the step edges of the substrate and exhibit long-range order. In a second step, hBN will be grown in between GNRs via deposition of precursor molecules consisting of B and N atoms. The seamless linking of hBN and GNRs will finally result in the formation of in-plane G-hBN superlattice. The structure, edge geometry, doping, electronic and magnetic properties of in-plane G-hBN superlattice will be studied by means of low temperature scanning tunneling microscopy. The success in fabrication of the proposed in-plane G-hBN superlattice will pave the way for application of graphene in future electronics.

本项目致力于发展一套有效的方法，实现石墨烯/六方氮化硼面内拼接超晶格结构的可控制备，优化石墨烯纳米带的能带调控工程，为将来基于石墨烯的微电子学、光电子学器件开发和应用开辟道路。为此，我们拟基于“自下而上”方法，采用两步法制备石墨烯/六方氮化硼面内拼接超晶格结构。我们将在超高真空环境下，首先利用高指数金属单晶表面作为模板，诱导石墨烯前驱物分子在模板表面生长石墨烯纳米带有序阵列；然后在石墨烯纳米带之间生长六方氮化硼，使其与石墨烯纳米带在面内拼接成一个完整的单原子层厚的薄膜，从而获得石墨烯/六方氮化硼面内拼接超晶格结构，并利用扫描隧道显微镜原位研究其微观结构和电学、磁学特性。

石墨烯/六方氮化硼面内拼接超晶格结构的薄膜材料，有望达到石墨烯能隙调控的要求，并且易于进行微纳米加工和器件制备，从而满足微电子领域的实用化需要。为了制备石墨烯/六方氮化硼面内拼接异质结构，我们利用超高真空分子束外延技术和极低温强磁场扫描隧道显微镜，首先研究了多种有机分子前驱物在Au(111)、Cu(110)、Ru(0001)、Au(788)等金属单晶表面的吸附和自组装；发现具有手性的hemifullerene分子吸附在Cu(110)表面发生手性识别，诱导Cu(110)表面发生手性再构，并且这种手性识别可用经典的三点接触模型描述；研究了Ru(0001)、Ni(111)、Pt(111)等金属单晶表面外延石墨烯的结构和物性；发现Ni(111)表面外延生长单层石墨烯中的皱褶可展现类似石墨烯纳米带中的自旋极化边缘态；发现Pt(111)表面外延生长的单层石墨烯可有效的屏蔽金属基底的自由电子，调控铅纳米岛的超导电性；在Ru(0001)表面实现了石墨烯/六方氮化硼面内拼接异质结构的可控制备；在Au(111)表面成功制备了含硫石墨烯纳米带和石墨烯/六方氮化硼面内拼接异质结构。这些结果对于未来石墨烯在纳米电子学期间中的应用有重要意义。完成了项目的研究内容，达到了预期目标。