Preface on: 'Challenges and Opportunities for 2D Materials and Heterostructure Devices'

摘要

The quest for new physical and chemical properties to discover new phenomena has given birth to low-dimensional (nD; n=0,1, and 2) nanomaterials. Two-dimensional (2D) materials are atomically thin layers with an electronic band structure different from their bulk (3D) counterparts and possess extraordinary electrical, magnetic, optical, mechanical, catalytic, and chemical properties. Top-down chemical or physical exfoliation and bottom-up chemical vapor deposition approaches are used to prepare 2D materials with crystal sizes ranging from as small as few micrometers to as large as wafer scales. Since the discovery of graphene in 2004, the family of 2D materials is ever expanding and now includes a diverse group of 2D materials in the list including 2D insulators such as hexagonal boron nitride (h-BN) and 2D semiconductors such as a family of transition metal dichalcogenides (TMDs) and monochalcogenides. What is more interesting is to combine these 2D materials to create engineered heterostructures for exploiting the cooperative advantage of different 2D layers. Such 2D materials can be interfaced with other 2D materials through the van der Waals weak forces and without any requirements of lattice matching. Such engineered van der Waals heterostructure has shown to unveil unique phenomena such as bandgap opening in graphene when placed on h-BN, unconventional superconductivity in twisted heterostructures of bilayer graphene, and unconventional ferroelectricity in twisted bilayer h-BN. Furthermore, mixed-dimensional van der Waals heterostructures (2D + nD; n =0, 1, and 3) have revolutionized the application space as such as photovoltaic response in graphene-on-bulk semiconductor heterojunc-tions, field-effect transistor applications, and hybrid organic/ inorganic heterostructures.