Zonal structure of graphene-like 2D allotropes of silicon carbide

The study investigates the energy characteristics of low-dimensional structures based on monolayers of 2D silicon carbide (2D-SiC). From the entire variety of possible polytypic forms, a subclass of graphene-like structures with a number of layers from 1 to 4 is distinguished. As a result of the analysis of the obtained data, dependencies of the band gap width and the location of the zone boundaries on the type of packing were identified. It was established that in the studied range of the number of layers, with constant stoichiometry, the layer-by-layer growth of structures leads to a decrease in the band gap width, and a change in the mutual orientation of the layers in the structure leads to a shift of the extrema on the band diagram and the formation of both direct and indirect bandgap semiconductors. The results allowed us to substantiate the reasons for the observed patterns from a physical point of view. The discrete series of bandgap widths of the investigated subset of structures ranges from 0.82 to 2.15 eV, covering the spectrum from visible to the IR range. The change in the crystal lattice of the ABAB structure and the reduction of the bandgap width to near-zero is of interest.