Semiconducting and Superconducting Properties of 2D Hexagonal Materials

The beginning of high interest in two-dimensional crystals dates back to the synthesis of graphene, which constitutes an exemplary monolayer material. This is due to the multiple extraordinary properties of graphene, particularly in the field of quantum electronic phenomena. However, there are electronic features that are notably missing in this material due to the inherent nature of its charge carriers. Of particular importance is the fact that pristine graphene does not exhibit semiconducting or superconducting properties, which prevents some applications. Certain modifications to graphene or even the synthesis of sibling materials are needed to obtain semiconducting and superconducting two-dimensional hexagonal materials. Here, the representative examples of such materials are discussed in detail, along with their expected properties. Special attention is paid to the unique semiconducting and superconducting phenomena found in these materials, e.g., the non-adiabatic superconductivity, spin- and valley-dependent conductivity, or the bulk-like Schottky-type potential barriers. The discussion is supplemented with some pertinent conclusions and perspectives for future work.