Two-dimensional type-II XSi2P4/MoTe2 (X = Mo, W) van der Waals heterostructures with tunable electronic and optical properties

Abstract

Recently, the synthesized two-dimensional (2D) MoSi₂P₄ monolayer with excellent environmental stability and suitable bandgap has attracted considerable attention. Here, we systematically investigated the structural, electronic and optical properties of the XSi₂P₄/MoTe₂ (X = Mo, W) van der Waals heterostructures (vdWHs) based on first-principles calculations. Our results demonstrate that the type-II MoSi₂P₄/MoTe₂ (WSi₂P₄/MoTe₂) possesses a direct bandgap of 0.258 eV (0.363 eV) at the PBE level. The biaxial strain and external electric field can effectively modulate the band alignment of the heterostructures from type-II to type-I and achieve a semiconductor–metal transition. Additionally, WSi₂P₄/MoTe₂ exhibits superior optical adsorption compared to their individual components in the visible-light region. The adsorption coefficient of MoSi₂P₄/MoTe₂ reached up to 10⁶ cm⁻¹ in the ultraviolet region. The work provides a valuable theoretical guidance for the design of optoelectronic devices based on XSi₂P₄/MoTe₂ vdWHs and indicates that the XSi₂P₄/MoTe₂ vdWHs show promising application in the nanoelectronic and optoelectronic fields.