Van der Waals Heterostructures of 2D Materials

随着曼彻斯特大学发现石墨烯，2D材料(2DM)的出现在英国率先出现，为材料科学开辟了一条新的途径。2DM源于具有共价层内键和弱范德华(VDW)层间耦合的大块层状晶体，通过将不同的原子薄层组合成异质结构，提供了创造新的按需杂化材料的机会，其性能根据特定应用而量身定做。这类晶体的家族包括石墨烯、六方氮化硼(HBN)、磷烯、过渡金属二卤化物(TMD，如MoS2、MoSe2、WS2、WSe2、NbSe2等)、过渡后金属硫化物(InSe、Gase)、金属三卤化物(CrI3、CrBr3、CrCl3)，以及许多其他已通过机械剥离从大块晶体分离、或外延生长为单层或双层晶体的晶体。总的来说，这些范德华材料涵盖了广泛的性质，从导电到绝缘，从透明到不透明，从抗磁到铁磁，从机械刚性到顺应性，它们的异质结构已经被证明提供了各种吸引人的功能，包括隧道晶体管、发光二极管、光电探测器和各种传感器。这种新的材料发现方法创造的机会几乎是无穷无尽的，学术出版社每天发表的数十篇研究和概念验证出版物以及每年数百项专利都证明了这一点。为了加速新材料的发现并优化异质结构中的材料选择，在国家石墨烯研究所，我们使用“原子乐高”方法，通过创建从大块晶体提升的2D层的异质结构来了解它们的性质，然后创建定制的设备，其中几种功能(例如，光电或/和传感)结合在混合材料的几个纳米厚度内。这样，我们能够快速且经济高效地确定有前景的应用系统，以便以后可以通过自上而下的大规模生产方法(如从油墨打印、CVD或MBE生长)来研究这些系统。通过将NGI的独特专业知识和能力与C2 DM和CIQM的互补专业知识和能力相结合，NGI将在未来十年确保英国在2 DM S&T领域的世界领先地位。

The advent of 2D materials (2DM), pioneered in the UK with the discovery of graphene at the University of Manchester, has opened a new avenue in materials science. Derived from bulk layered crystals with covalent intra-layer bonds and a weak van der Waals (vdW) interlayer coupling, 2DM offer an opportunity to create new hybrid "materials on demand" with properties tailored to particular applications, by combining different atomically thin layers into heterostructures. The family of such crystals includes graphene, hexagonal boron nitride (hBN), phosphorene, transition metal dichalcogenides (TMD, such as MoS2, MoSe2, WS2,WSe2, NbSe2, etc), post-transition metal chalcogenides (InSe, GaSe), metal tri-halides (CrI3, CrBr3, CrCl3), among many others already separated from bulk crystals by mechanical exfoliation, or grown epitaxially in the form of monolayer or bilayer crystals. Collectively, these van der Waals materials cover a wide range of properties, from conductive to insulating, from transparent to opaque, from diamagnetic to ferromagnetic, from mechanically stiff to compliant, and their heterostructures have already been shown to offer various appealing functionalities including tunnelling transistors, light emitting diodes, photodetectors, and various sensors. The opportunities created by this new approach to materials discovery are almost endless, as proven by dozens of research and proof-of-concept publications appearing in academic press daily and hundreds of patents annually. In order to speed up the new materials discovery and optimise the choice of materials in heterostructures, at National Graphene Institute we use 'atomic LEGO' approach by creating heterostructures of 2D layers lifted from bulk crystals to understand their properties and, then, to create bespoke devices where several functionalities (e.g., optoelectronic or/and sensing) are combined within only few nanometre thickness of the hybrid material. This way, we are able to identify quickly and cost efficiently the promising systems for applications, so that those could be later studied subject to the top-down mass production methods (such as printing from inks, CVD or MBE growth). By combining the unique expertise and capability of NGI with complementary expertise and capabilities of C2DM and CIQM, NGI will secure UK's world-leading position in 2DM S&T for the next decade.