Theoretical exploration of promising optoelectronic two-dimensional materials MSi2N4 (M=Cr, Mo, W)

The electronic properties of two-dimensional MSi2N4 (M = Cr, Mo, W) monolayer have been have systematically investigated by strain, electric field, bilayer heterostructures, and adsorption of environmental gas molecules. The results indicate that MSi2N4 have excellent thermodynamic, chemical stability and they are semiconductor materials with perfect absorption performance in the visible and ultraviolet regions. As the tensile strain increases, the band gap of MSi2N4 gradually decreases, and these two-dimensional monolayer materials undergo a phase transition from semiconductor to spin gapless semiconductor to half-metal to metal. The bilayer heterostructures and the external electric field can effectively regulate the band gap of the MSi2N4 monolayer. Some environmental gas molecules can be effectively adsorbed, and the vast majority of adsorption models do not affect the band gap of the MSi2N4. The diverse physical properties and adjustable bandgap characteristics exhibited by MSi2N4 mean that they are promising candidate for optoelectronic functional materials.