First-principles studies of SnS2, MoS2 and WS2 stacked van der Waals hetero-multilayers

Abstract

We present the energetics, structural and electronic properties of SnS 2 monolayer stacked with MoS 2 and WS 2 monolayers making the van der Waals heterolayers using the first-principles methods. The exchange-correlation functionals used are the LDA, GGA functionals as well as the newly developed variants of non local van der Waals (vdW) exchange-correlation functionals, namely vdW-DF-revPBE and vdW-DF2-C09. We also considered the combinations of hetero-layers that involve all the three SnS 2 , MoS 2 and WS 2 stacked together. All the investigated hetero-layers have a short decay (offset) of the equilibrium lattice parameters compared to the SnS 2 single layer one. Except for the GGA-PBE functional, all the functionals predict the interlayer distances closer to the previous theoretical and experimental studies. The hetero-layers that have relative low binding energies are indirect band gap semiconductors, while those with dramatically high binding energies are weakly or strongly metallic. This study gave another avenue of altering the energetics and electronic properties of SnS 2 monolayer through vertical stacking with MoS 2 and WS 2. The variation in band gap enables these newly predicted hetero-layers to be suitable candidates for designing novel devices for nanoelectronic and optoelectronic technology, which includes energy storage, photodetectors, thermophotovoltaic.