Geometric and Electronic Structures of Two-Dimensional SiC3 Compound

Although graphene is an unconventional semimetallic nanosheet, the graphene-like binary sheets, such as BN and SIC with 1:1 stoichiometry, usually discard the semimetallicity. Here, we report the geometric structures and electronic properties of the two-dimensional SiC3 sheet by the particle-swarm optimization method and density functional calculations. The unbiased global search reveals three lowest-energy structures for SiC3 ones, all of which are Si-graphene hybrid honeycomb lattices with robust dynamical stabilities. Depending on the ordered arrangement of Si atoms, the SiC3 sheets could be direct-band-gap semiconductors or zero-band-gap semimetals. More interestingly, the semiconducting SiC3 sheet has a strong adsorption ability in the visible-light region, and the semimetallic one even possesses a distorted Dirac cone, which induces an anisotropic Fermi velocity. These rich electronic properties of SiC3 nanosheets endow the system with promising applications in nanoelectronics and photovoltaics.