  With the reported synthesis of a fully planar 2D silicon carbide (SiC)
allotrope, the possibilities of its technological applications are enormous.
Recently, several authors have computationally studied the structures and
electronic properties of a variety of novel infinite periodic SiC monolayers,
in addition to the honeycomb one. In this work, we perform a systematic
first-principles investigation of the geometry, electronic structure,
vibrational, and optical absorption spectra of several finite, but, fully
planar structures of SiC, i.e., 0D quantum dots (QDs). The sizes of the studied
structures are in the 1.20--2.28 nm range, with their computed HOMO(H)-LUMO(L)
gaps ranging from 0.66 eV to 4.09 eV, i.e., from the IR to the UV region of the
spectrum. The H-L gaps in the SiC QDs are larger as compared to the band gaps
of the corresponding monolayers, confirming the quantum confinement effects. In
spite of covalent bonding in the QDs, Mulliken charge analysis reveals that Si
atoms exhibit positive charges, whereas the C atoms acquire negative charges,
due to the different electron affinities of the two atoms. Furthermore, a
strong structure property relationship is observed with fingerprints both in
the vibrational and optical spectra. The wide range of H-L gaps in different
SiC QDs makes them well-suited for applications in fields such as
photocatalysis, light-emitting diodes, and solar cells.
