Study of the electronic and optical properties of doped gallium sulfide monolayer by first principles calculations

The present paper investigates the electronic and optical behavior of monolayer gallium sulfide as a transition metal monochalcogenide, doped with IV and V group atoms of the periodic table. The calculations are performed in the SIESTA software package based on density functional theory using the exchange correlation function and the generalized gradient approximations. Analysis of the electronic structure of this material shows that the pure gallium sulfide monolayer has an indirect band gap of 2.3 eV. In order to investigate the effects of impurities on this structure, the impurity atoms of groups IV and V were applied in the position of sulfur and gallium atoms. The impurity concentration of doped structures is 1.14%. The simulation results show that the presence of this impurity, depending on the type of impurity atom and its location, leads to a transition from semiconductor to metal, indirect to direct semiconductor or non-magnetic to magnetic state in this structure. For example, when Sb is doped to the gallium sulfide monolayer in the position of the sulfur atom, this system is magnetic with a direct band gap, while its replacement by the gallium atom preserves the semiconductor nature of the indirect band gap structure with less gap energy. In addition to the electronic properties, the optical properties of the alloyed structure were also analyzed. The results show that the GaS structure of the alloyed alloy with elements of the fourth and fifth groups opens the way for nanoelectronics, optoelectronics and spintronics applications.