Two-dimensional silicon phosphide: low effective mass and direct band gap for future devices applications

The band engineering using strain and electric field of monolayer silicon phosphide (2D-SiP) has been investigated byfirst-principlecalculation. The biaxial strain is used to tune the electronic band gap from 1.91 to 0.7eV by applying compressive strain 0-10% and 1.91-1.0eV by tensile strain from 0 to 12%. Furthermore, SiP shows metallic behaviour beyond 12% of compressive strain and 14% of tensile strain. However, the negligible effect of the external electric field on the electronic band structure of 2D SiP shows the sustainability of the monolayer. The stress vs strain curve shows the excellent mechanical stability of the monolayer SiP. 2D SiP also shows low electron effective mass for higher carrier mobility. Further, optical properties of the monolayer show the UV region absorption. Our results provide insights to possible mechanical tuning of SiP monolayer by applying external strain for nano-electronic and nano-optoelectronic device application.