  The electrical, magnetic, thermal and optical characteristics of Gallium (Ga)
doped silicene are investigated using density functional theory (DFT). The
effect of doping is studied by tuning dopant concentrations as well as
examining varied doping distances, and atomic dopant interactions for the same
substitutional doping concentration. The results indicate that the Ga atoms
alter the band structure and the band gap in the silicene monolayer at various
concentrations, which can be referred back to to the repulsive interaction of
Ga-Ga atoms. The band gap is determined by the interaction strength of the
Ga-Ga atoms, the Coulomb repulsive force, and it does not always widen as
doping concentration increases. In addition, our spin-polarized DFT
calculations show that these monolayers behave like nonmagnetic semiconductors,
exhibiting symmetric spin-up and spin-down channels. The repulsive interaction
between the Ga atoms causes a symmetry breaking of the monolayers. As a
consequence, a Ga dopant can open the band gap, leading to better
thermoelectric properties such as the Seebeck coefficient and the figure of
merit, as well as an increase in the optical response. As a result of our
estimates, Ga doped silicene monolayers could be advantageous in thermoelectric
and optoelectronic devices.
