The Design Of ZnS-based Two Dimensional Structures And Quantum Properties

All of the computations are calculated using the density functional theory(DFT)method through first-principles calculations,as implemented in the VASP software under generalized gradient approximation(GGA).In our work,we investigate the electronic properties and band structures of two dimensional ZnS nanosheets and stanene materials.Firstly,Density-functional theory has been applied to investigate the electronic and optical properties of two-dimensional ZnS nanosheets.A calculation has been carried out within the PBE-GGA.The electronic properties of 2D-ZnS have been derived by the examination of the electronic band structures and density of states.The optical properties have been determined through the study of the dielectric function,the absorption index,reflectivity,refractive and electron loss function.A thorough study of the dielectric function has been performed so that the peaks and the transition bands have been specified.Secondly,we study on the electronic structure of the V,VI group atoms(N,P,As,Sb,O,Se,Te)doped two-dimensional ZnS nanosheets.The cmputational results show that the intrinsic ZnS nanosheets structure is a nonmagnetic wide band gap of the direct band-gap semiconductor material with a band gap of 2.733 eV.It is shown that when the V group atoms(N,P,As,Sb)are doped with ZnS,the single layer ZnS is spin-polarized to produce magnetic properties,while the VI group atoms(O,Se,Te)doping will make a single layer of ZnS structure to produce magnetic.In the experiment,we also found that V,VI group atoms doped ZnS system which still maintain the direct conductor semiconductor properties.we also calculated the electronic properties and magnetic properties of 3d transition metal atoms adsorbed by two-dimensional ZnS nanosheets.The calculated results indicate that the lowest energy position in the adsorption system is directly above the S atom in the ZnS nanosheets.In the case of atomic adsorption,Ni atoms form a covalent bond with ZnS nanosheets and belong to chemical adsorption.For the adsorption of Mn atoms and Fe atoms,there is no bonding with ZnS thin films,which belongs to physical adsorption.Then we further calculated the electronic properties and energy band structure of the three adsorbed atomic systems.We found that the Mn atom adsorption system is a magnetic semiconductor with a magnetic moment of 4μ.The Fe adsorption system is a semi-metallic property,And the magnetic moment is 5μ.For the system adsorbed by Ni atoms,the system exhibits a non-magnetic semiconducting property with a band gap of 0.667 eV due to the bond between the Ni atom and the ZnS thin film.Then,through the first-principles calculation,we hydrogenated the 2D ZnS structure,and studied two methods: double-sided hydrogenation and single-sided hydrogenation.By calculating the formation energy,we find that the double-sided hydrogenated ZnS structure is more stable,both of which are expressed as indirect band gap semiconductors.Further studies have shown that the band gap can become a direct band gap by applying biaxial stress.we study the geometrical and electronic properties of zinc sulfide / silicon(111)heterojunctions based on the first-principles.In both configurations,the interaction between the zinc sulfide film and the silicon(111)substrate is van der Waals force.The bandgap of the heterojunction is between the two-membered and is mainly derived from the silicon(111)substrate.In addition,the bandgap of the heterojunction can be well controlled by stress and interlayer spacing,and the transition of the indirect bandgap to the direct bandgap can be achieved,which ensures that it can be used in optics.Finally,we propose an adsorption way that in 2D arsenicene film decorated with-CN(AsCN).By activating the px and py orbitals of arsenicene with OFE,the band-gap of germanene decorated with-CN can be enhanced to 180 meV as a representative example.The physics of the QSHE can be identified by s–pxy band inversion,topological invariant Z2 = 1,and helical edge states in the bulk band-gap.It is noteworthy that AsCN films are intrinsic TIs over a wide range of strains.In addition,AsCN films on h-BN sheets have been obtained to support the QSHE,which contain a Dirac cone lying within the band gap.