Strain-driven tunable electronic and optical properties of bilayer MoSi2N4: A many-body calculation

Abstract

Tunable electronic and optical properties in two-dimensional (2D) systems are of particular importance for their optoelectronic applications. Through first-principles calculations, stability and electro-optical properties of bilayer MoSi₂N₄ are mainly explored under biaxial strains. The bilayer MoSi₂N₄ has an energetic/dynamical stability by the binding energy/phonon dispersion. The bilayer is judged to be an indirect semiconductor and possesses a bandgap of 1.632 eV (PBE)/2.681 eV (G₀W₀). The bandgap can be greatly altered in a strain range from −5% (compressive) to +5 % (tensile), and indicates a transition of bandgap characteristics (indirect to direct) at a compressive strain of −2.9 %. Furthermore, biaxial tensile strain on MoSi₂N₄ bilayer significantly improves its light absorption in the visible region, causing a red-shift of the absorption spectrum, while compressive strain induces a blue-shift. These results suggest that MoSi₂N₄ bilayer is a promising candidate of strain-tuned optoelectronic devices.