One of the many things that were revealed with the isolation of graphene, was the pursuit of atomically thin forms of other materials: semiconductors, boron nitride and, more recently, Xenes, are offering endless possibilities not only to explore fundamental physics, but also to demonstrate improved or even entirely novel applications.
2D materials have a lot to offer in terms of optoelectronics applications and in a wide range of wavelengths (microwave to the visible), as they exhibit something that graphene does’t have: a bandgap. Tony Low, Frank Koppens and colleagues review the physics and applications of different kinds of polaritons (exciton-, plasmon- and phonon) in layered 2D materials.
Alessandro Molle, Deji Akinwande and collaborators offer a critical overview of the issues that remain open when it comes to Xenes, where atoms from the group IVA elements are organized into a single layered, honeycomb-like lattice. Several issues remain still under debate, such as their stability, while various theoretical studies are predicting a plethora of interesting topological properties.
A unique characteristic of 2D materials, however, is the possibility to easily form (horizontal or vertical) van der Waals heterostructures, following the stacking of layers of different materials and thicknesses. Such heterostructures however are not only limited to combinations of 2D materials; Deep Jariwala, Tobin Marks and Mark Hersam explain in their Review that 2D materials can be combined with non-2D materials, such as organic molecules and quantum dots (0D), carbon nanotubes (1D) and bulk Si, Ge, III–V and II–VI semiconductors (3D), that adhere primarily through non-covalent interactions.
Maria Maragkou (Nature Materials)