First-principles investigations of electronic property modulation in the FeCl ₃ /MoSi ₂ N ₄ heterojunction by strain, interlayer distance and vertical electric field variation

This study investigated the changes in the electronic properties of the FeCl₃/MoSi₂N₄ heterostructure by modulating interlayer distance, in-plane strain, and external electric field. The results indicated that the FeCl₃/MoSi₂N₄ van der Waals heterostructure (vdWH) is an indirect band gap semiconductor with a band gap of 1.21/2.21 eV, as determined by a PBE/HSE06 calculations, and forms a type-I heterojunction. The equilibrium interlayer distance (Δ<i>D</i>) is 3.35 Å and altering it results in a decrease in the band gap. Subsequently, a biaxial strain (<i>ε</i>) was applied to the heterostructure. With compressive strain, the band gap shows a linear decrease. When <i>ε</i> = -4%, the material changes from semiconductor to metallic state. Under tensile strains ranging from 1 to 3%, the band gap sharply decreases from 0.89 to 0.22 eV. Under a vertical external electric field in the -0.7 to 0.8 V Å^-1 range, the band gap stabilizes at around 0.9 eV. Notably, at -0.8 V Å^-1, the band gap reaches zero.