Electronic Properties of Novel Two-Dimensional Si_xC_y568

a new type of two-dimensional (2D) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Si}_{X}\mathrm{C}_{\mathrm{y}}$</tex> semiconductor material with the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$sp^{2}+sp^{3}$</tex> hybridization is proposed in this paper. The crystal unit cell consists of pentagon, hexagon, and octagon rings, referred to as <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\mathrm{D}-\text{Si}_{X}\mathrm{C}_{y}568$</tex>. The stability in terms of energy and dynamics as well as structure parameters and basic electronic properties of the unit cell were investigated using first-principles calculation, based on the density functional theory (DFT). The results indicate that the proposed <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2\mathrm{D}\ \text{Si}_{1} \mathrm{C}_{12}568$</tex> is stable in terms of energy and dynamics, with an indirect bandgap of 0.97 e V. The conduction band minimum and the valence band maximum are located at the G and M points of the Brillouin Zone, respectively. The minimum effective mass of electrons is 0. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$44m\mathrm{o}$</tex>, it is close to the effective mass of C568, which suggests that it could be a semiconductor material with a very high mobility. The calculated result of the carriers' mobility indicates that the electron mobility is very high, reaching up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.44\times 10^{4}\text{cm}^{2}\mathrm{s}^{-1}\mathrm{V}^{-1}$</tex>.