Title: Computational insights and the observation of SiC nanograin assembly: towards 2D silicon carbide,
Abstract: While an increasing number of two-dimensional (2D) materials, including
graphene and silicene, have already been realized, others have only been
predicted. An interesting example is the two-dimensional form of silicon
carbide (2D-SiC). Here, we present an observation of atomically thin and
hexagonally bonded nanosized grains of SiC assembling temporarily in graphene
oxide pores during an atomic resolution scanning transmission electron
microscopy experiment. Even though these small grains do not fully represent
the bulk crystal, simulations indicate that their electronic structure already
approaches that of 2D-SiC. This is predicted to be flat, but some doubts have
remained regarding the preference of Si for sp$^{3}$ hybridization. Exploring a
number of corrugated morphologies, we find completely flat 2D-SiC to have the
lowest energy. We further compute its phonon dispersion, with a Raman-active
transverse optical mode, and estimate the core level binding energies. Finally,
we study the chemical reactivity of 2D-SiC, suggesting it is like silicene
unstable against molecular absorption or interlayer linking. Nonetheless, it
can form stable van der Waals-bonded bilayers with either graphene or hexagonal
boron nitride, promising to further enrich the family of two-dimensional
materials once bulk synthesis is achieved.