离子束溅射外延h-BN二维原子晶体及其与石墨烯异质结构研究

六角氮化硼（h-BN）与石墨烯晶格常数匹配，可实现原子级的平整度，且其表面极少存在悬挂键和电荷陷阱，有利于保持本征石墨烯极高的载流子迁移率，因此石墨烯/h-BN异质结构成为近年来的研究热点。除了机械剥离，大部分实验研究采用化学气相沉积（CVD）制备h-BN薄层，但CVD生长过程复杂，各种生长参数相互关联，且选择合适的前驱体存在困难。离子束溅射是一种成熟且应用广泛的物理气相沉积技术，目前尚未有利用离子束溅射制备h-BN的报道。我们拟采用离子束溅射在Cu或Ni单晶薄膜上外延生长h-BN二维原子晶体，并结合CVD技术制备石墨烯/h-BN异质结构。通过直接沉积的方式可以获得大面积、任意形状的样品，而且可避免转移过程引入的污染，提高石墨烯/h-BN的界面质量。通过该项目的实施，期望实现高质量石墨烯/h-BN异质结构的可控制备，探明异质结构的成核和生长机制，为大面积石墨烯电子学的应用奠定基础。

Hexagonal boron nitride (h-BN) has the same atomic structure as graphite with a small lattice mismatch, and its lamellar nature provides it an atomically flat surface. Furthermore, owing to the absence of dangling bonds and charge traps at the surface of h-BN, using h-BN as substrate for graphene is favorable for keeping its outstanding intrinsic properties such as extremely high carrier mobility. Therefore, the graphene/h-BN heterostructure has attracted great attention for high-quality graphene electronics. Besides micromechanical exfoliation, few-layer h-BN films were prepared by chemical vapor deposition (CVD) in the most experiments. However, the complex set of interrelated growth parameters governs CVD processes, and a suitable precursor is not yet available. Physical vapor deposition, a scalable, industry-compatible process, can avoid these issues. In the present project, we firstly propose to grow few-layer h-BN epitaxial films on Cu (111) or Ni (111) substrates by ion beam sputtering, and the fabrication of graphene/h-BN heterostructure is realized by combining with CVD method. The direct deposition of the heterostructure not only offers the possibility of large-area synthesis of these materials, but also results in the high quality interfaces between graphene and h-BN, which is beneficial to the carrier transport in CVD graphene. The goal of the present project is realizing the controllable fabrication of high-quality graphene/h-BN heterostructure and elucidating the mechanism of heterogeneous nucleation and growth. This project is significant from the view of both fundamental research of growth of graphene heterostructure and applications of large-area graphene-based electronics.