First Principles Study On Electronic Structure Of Van Der Waals Heterostructures Based On Tin Dichalcogenides

Tin dichalcogenides are Earth-abundant layered metal dichalcogenides whose bulk crystal have long been investigated for photovoltaics and photoelectrochemistry.Driven by the exploration into low-dimensional limits,high-quality few-layer and monolayer tin dichalcogenides have been chemically and mechanically exfoliated from their layered-structure crystals and then used in electronic and optoelectronic applications.Recently,reports have also emerged on multilayer systems based on SnS₂ and SnSe₂.However,the studies to date of heterolayers based on tin dichalcogenides are still inadequate,and further possible structures and properties remain unknown and await exploration.Herein,we investigate six examples of vd W heterostructures based on tin dichalcogenides via first-principle calculations.These interfaces were constructed from combinations of SnS₂(SnSe₂)with graphene,Hf S₂,and Zr S₂.Our study shows that all the heterolayers behave as a semiconductor with an indirect bandgap,except those that contain graphene,which behave as a metal.Besides,to meet the various requirements of different devices,the tunable electronic properties of two-dimensional materials are of great importance to their applications,and applying strain to bilayer systems is a widely used means to achieve the goal.Consequently,we pay special attention to how an in-plane biaxial strain changes the material properties,and our results reveal that both tensile and compressive strain can effectively tune the band structures of semiconducting systems based on tin dichalcogenides.Specifically,reduced bandgaps due to compressive strain lead ultimately to a semiconductor-to-metal phase transition in all the heterolayers,and variations in band edges due to tensile strain alter the carrier effective masses appreciably.Analyzing the projected density of states(PDOS)and charge density difference indicates that these changes originate from the shifts in energy states and transfer of interlayer charges under the applied strain,which varies the inter-atomic distances and therefore changes the atomic orbital superimposition.Being able to tune the material properties in such a controlled manner makes heterostructures based on tin dichalcogenides promising candidates for use in nanoscale electronic and optoelectronic devices.