Interlayer interaction controlling the properties of AB- and AA-stacked bilayer graphene-like BC14n and si2c14

Abstract

We model bilayer graphene-like materials with Si2C14 and BC14N stoichiometry, where the interlayer interactions play important roles shaping the physical properties of the systems. We find the interlayer interaction in Si2C14 to be repulsive due to the interaction of Si-Si atoms, and in BC14N it is attractive due to B and N atoms. The repulsive interlayer interaction opens up a bandgap in Si2C14 while the attractive interlayer interaction in BC14N induces a small indirect bandgap. Furthermore, the repulsive interaction decreases the Young modulus while the attractive interaction does not influence the Young modulus much. The stress-strain curves of both the AA- and the AB-stackings are suppressed compared to pure graphene bilayers. The optical response of Si2C14 is very sensitive to an applied electric field and an enrichment in the optical spectra is found at low energy. The enrichment is attributed to the bandgap opening and increased energy spacing between the π-π* bands. In BC14N, the optical spectra are reduced due to the indirect bandgap or the overlapping of the π-π* bands. Last, a high Seebeck coefficient is observed due to the presence of a direct bandgap in Si2C14, while it is not much enhanced in BC14N.