BilayerSnS2: Tunable stacking sequence by charging and loading pressure

Abstract

Employing density functional theory-based methods, we investigate monolayer and bilayer structures of hexagonal SnS 2 , which is a recently synthesized monolayer metal dichalcogenide. Comparison of the 1H and 1T phases of monolayer SnS 2 confirms the ground state to be the 1T phase. In its bilayer structure we examine different stacking configurations of the two layers. It is found that the interlayer coupling in bilayer SnS 2 is weaker than that of typical transition-metal dichalcogenides so that alternative stacking orders have similar structural parameters and they are separated with low energy barriers. A possible signature of the stacking order in the SnS 2 bilayer has been sought in the calculated absorbance and reflectivity spectra. We also study the effects of the external electric field, charging, and loading pressure on the characteristic properties of bilayer SnS 2 . It is found that (i) the electric field increases the coupling between the layers at its preferred stacking order, so the barrier height increases, (ii) the bang gap value can be tuned by the external E field and under sufficient E field, the bilayer SnS 2 can become a semimetal, (iii) the most favorable stacking order can be switched by charging, and (iv) a loading pressure exceeding 3 GPa changes the stacking order. The E-field tunable band gap and easily tunable stacking sequence of SnS 2 layers make this 2D crystal structure a good candidate for field effect transistor and nanoscale lubricant applications.

Vacancy‐ and doping‐dependent electronic and magnetic properties of monolayer SnS2

“…The bond length near the vacant site reduces to 2.55 Å and 2.54 Å for the Sn‐ and S‐vacant systems (Figure B,C), respectively, which indicates that the neighboring Sn or S atoms move away from the vacant position. Our computed structure parameters are in agreement with the other reported values of SnS 2 with and without vacancy …”

“…For pristine monolayer SnS 2 , the lattice constant and the bond distance between Sn and S are estimated to be 3.69 Å and 2.59 Å, respectively. We extend the unit cell to a supercell of 4 × 4 × 1 to create vacancy at the Sn and S sites, as shown in Figure B,C.…”

“…Before going to see the effects of vacancy and M / X doping in monolayer SnS 2 , first, we have discussed the properties of its pristine form. The DOS of pristine monolayer SnS 2 is depicted in Figure , indicating the band gap of 2.43 eV . The valence band maximum (VBM) mostly consists of S‐3 p states while the hybridization of S‐3 p and Sn‐5 s states is dominated in the conduction band minimum (CBM).…”

Low‐Temperature Wafer‐Scale Deposition of Continuous 2D SnS2 Films

“…Commercial ALD equipment exists for coating 12″ wafers or even larger substrates as well as batches of over 100 wafers, which allow further upscaling of the present process. The as‐deposited SnS 2 films were amorphous, and crystallized upon annealing forming smooth, continuous films with the expected layered SnS 2 structure (Figure c,d) …”

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

“…In this work, all the calculations were performed on the most stable phase of SnS 2 , MoS 2 and WS 2 [8,25,48], showing a layered CdI 2 -type structure in which the metallic atom is sandwiched between two S atoms in a hexagonal closed packed lattice shown in Figure 1. Using the GGA-PBE functional only, we performed the structural optimization of SnS 2 , MoS 2 and WS 2 isolated monolayers to calculate the equilibrium in-plane lattice constants, and thereafter their band structures were plotted to examine the electronic properties.…”