Predicting 2D silicon allotropes on SnS2

A first principles study on the stability and structural and electronic properties of two-dimensional silicon allotropes on a semiconducting layered metal-chalcogenide compound, namely SnS 2 , is performed. The interactions between the two-dimensional silicon layer, commonly known as silicene, and the layered SnS 2 template are investigated by analyzing different configurations of silicene. The calculated thermodynamic phase diagram suggests that the most stable configuration of silicene on SnS 2 belongs to a family of structures with Si atoms placed on three different planes; so-called dumbbell silicene. This particular dumbbell silicene structure preserves its atomic configuration on SnS 2 even at a temperature of 500 K or as a “flake” layer (i.e., a silicene cluster terminated by H atoms), thanks to the weak interactions between the silicene and the SnS 2 layers. Remarkably, an electric field can be used to tune the band gap of the silicene layer on SnS 2 , eventually changing its electronic behavior from semiconducting to (semi)metallic. The stability of silicene on SnS 2 is very promising for the integration of silicene onto semiconducting or insulating substrates. The tunable electronic behavior of the silicene/SnS 2 van der Walls heterostructure is very important not only for its use in future nanoelectronic devices, but also as a successful approach to engineering the bang-gap of layered SnS 2 , paving the way for the use of this layered compound in energy harvesting applications.