  Two-dimensional (2D) materials with Dirac cones have been intrigued by many
unique properties, i.e., the effective masses of carriers close to zero and
Fermi velocity of ultrahigh, which yields a great possibility in
high-performance electronic devices. In this work, using first-principles
calculations, we have predicted a new Dirac cone material of silicon carbide
with the new stoichiometries, named g-SiC6 monolayer, which is composed of sp2
hybridized with a graphene-like structure. The detailed calculations have
revealed that g-SiC6 has outstanding dynamical, thermal, and mechanical
stabilities, and the mechanical and electronic properties are still isotropic.
Of great interest is that the Fermi velocity of g-SiC6 monolayer is the highest
in silicon carbide Dirac materials until now. The Dirac cone of the g-SiC6 is
controllable by an in-plane uniaxial strain and shear strain, which is promised
to realize a direct application in electronics and optoelectronics. Moreover,
we found that new stoichiometries AB6 (A, B = C, Si, and Ge) compounds with the
similar SiC6 monolayer structure are both dynamics stable and possess Dirac
cones, and their Fermi velocity was also calculated in this paper. Given the
outstanding properties of those new types of silicon carbide monolayer, which
is a promising 2D material for further exploring the potential applications.
