Bilayer SnS2: Easy-tunable Stacking Sequence by Charging and Loading Pressure

Physical Review B 93, 125403 (2016)

Bilayer SnS2: Easy-tunable Stacking Sequence by Charging and Loading Pressure

C. Bacaksiz,S. Cahangirov,A. Rubio,R. T. Senger, F. M. Peeters, H. Sahin

Employing density functional theory-based methods, we investigate monolayer and bilayer struc- tures of hexagonal SnS2, which is recently synthesized monolayer metal dichalcogenide. Comparison of 1H and 1T phases of monolayer SnS2 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 inter- layer coupling in bilayer SnS2 is weaker than that of typical transition-metal dichalcogenides (TMDs) so that alternative stacking orders have similar structural parameters and they are separated with low energy barriers. Possible signature of the stacking order in SnS2 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 SnS2. It is found that (i) the electric field increases the coupling between the layers at its prefered 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 SnS2 can become semi-metal, (iii) the most favorable stacking order can be switched by charging and (iv) a loading pressure exceeding 3 GPa changes the stacking order. E-field tunable bandgap and easy-tunable stacking sequence of SnS2 layers make this 2D crystal structure a good candidate for field effect transistor and nanoscale lubricant applications.

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This work was supported by the bilateral project between TUBITAK (through Grant No. 113T050) and the Flemish Science Foundation (FWO-Vl). The calculations were performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). CB, HS, and RTS acknowledge the support from TUBITAK Project No 114F397. supported by a FWO Pegasus Marie Curie Fellow- ship. SC and AR acknowledges financial support from the Marie Curie grant FP7-PEOPLE-2013-IEF Project No. 628876, the European Research Council (ERC-2010-AdG-267374), Spanish grant, Grupos Consolidados (IT578-13). SC acknowledges support from The Scientific and Technological Research Council of Turkey (TUBITAK) under the project number 115F388.

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