Theoretical insight on the effect of middle layer specifications on electronic properties of SnS₂/MX₂/SnS₂ Trilayer heterostructure (M = Mo, w; X = S, Se, Te)

Recently, the van der Waals (vdW) heterostructure design has gained paramount importance for realizing artificial two-dimensional (2D) material systems with tunable electronic/opto-electronic properties for different technological applications. Driven by this paradigm, in this work, a detailed theoretical analysis has been performed on the structural and electronic properties of different tri-layer van der Waals (vdW) heterostructure of SnS₂/MX₂/SnS₂ (M = Mo, W; X = S, Se, Te) via density functional theory(DFT) based Ab-initio calculation. Moreover, for individual vdW tri-layers, two characteristics of interlayer stacking configurations corresponding to natural stacking configurations of tri-layer SnS₂ and MX₂ have been considered. The structural properties are evaluated from the interlayer distance, bond angle, bond length, electrostatic difference potential, electron difference density, and Mulliken charge distributions. The electronic properties of different vdW tri-layers are assessed from the interlayer charge transfer, energy band structures, and the density of states profiles, which are quantified from the energy bandgap and effective masses, which are finally compared and benchmarked with homogenous tri-layer SnS₂. It has been observed that the chalcogen specification of the middle layer predominantly influences the interlayer interaction and thereby, structural/electronic properties of vdW tri-layers. The vdW tri-layers demonstrate metallic, semi-metallic, and semiconducting energy band structures (bandgap ranging from 0.138 to 0.729 eV, electron effective mass ranging from 0.286/0.286 m₀ to 1.299/0.342 m₀, hole effective mass ranging from 0.216/0.216 m₀ to 2.825/2.927 m₀) based on the middle layer MX₂ specifications and stacking orientations.