Pnictogen Atom Substitution to Modify the Electronic and Magnetic Properties of SiS2 Monolayer: A DFT Study

The density functional theory (DFT) is employed to study the modulation of electronic and magnetic properties of ${\mathrm{SiS}}_2$ monolayer through doping with pnictogen (P and As) atoms. ${\mathrm{SiS}}_2$ monolayer is intrinsically non-magnetic, exhibiting the semiconductor nature with indirect bandgap of 1.39(2.26) eV provided by standard(hybrid) functional. This 2D material is metallized under effects of single Si vacancy, single S vacancy, and pair Si─S vacancies. In the latter case, significant magnetism with a total magnetic moment of 1.55 ${\mu }_B$ is produced mainly by S atoms around the vacancy sites. The monolayer metallization takes place also when doping with P and As atoms at Si sublattice, preserving the nonmagnetic nature. Meanwhile, P and As substitution leads to the emergence of magnetism with total magnetic moments of 0.93 and 0.99 ${\mu }_B$, respectively. Herein, magnetic properties are produced mainly by the outermost $p$ orbital of pnictogen impurities. Interestingly, the results assert the emergence of the half-metallicity, which gives evidence of new highly spin-polarized 2D materials. Further, doping with pair P/P, As/As, and P/As atoms are also considered with different doping configurations. It is found that the nonmagnetic semiconductor nature is preserved upon doping with pair pnictogen atoms, however, the indirect-to-direct gap transition is induced. Moreover, the energy gap exhibits large reduction between 51.80% and 77.70%. The findings in this work may suggest the formation of prospective optoelectronic and spintronic 2D materials by doping ${\mathrm{SiS}}_2$ monolayer with pnictogen atoms.