Post-graphene 2D materials : successes and challenges

Since the breakthrough of graphene, two-dimensional (2D) materials have become a major field in material research, largely motivated by their outstanding electronic and optical properties that foresee their integration into a wide range of next-generation devices. In this context, 2D materials composed of post-carbon group 14 atoms, in particular silicon and germanium, have attracted a great deal of interest over the last fifteen years due to their valence electronic configuration similar to that of graphene and their widespread use in the semiconductor industry. Silicene, the silicon counterpart of graphene, has been particularly studied, both theoretically and experimentally. A key issue in exploiting the potential of silicene lies in its synthesis since no layered structure analogous to graphite exists for silicon. A state-of-the-art review on the different strategies developed to synthesize low-buckled Si honeycomb structures by epitaxial growth will be presented. The question of whether epitaxial silicene retains the peculiar electronic properties of free-standing silicene will be addressed. Finally, the reactivity and air-stability of silicene as well as the strategy devised to decouple epitaxial silicene from the underlying surface and its transfer to a target substrate will be discussed.

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