Coupling Effect And Defect Of Single-layer Transition Metal Disulfide,? Main Group Element And Metal Substrate

Two-dimensional materials such as graphene have a large specific surface area,and quantum confinement effects cause the separation of energy levels,which has led researchers to research on other two-dimensional atomic crystals of graphene-like structures.The atomic masses of silicon,germanium and tin with the same family of carbon are larger,and the spin-orbit coupling of corresponding two-dimensional single-layer is stronger,which is beneficial to induce the quantum spin Hall effect.Different from the semi-metallic nature of the above two-dimensional materials,the energy gap of single-layer transition metal disulfide?TMD?is in the range of 1?2 eV,which is advantageous in field effect transistor applications.In order to realize the industrial application value of single-layer IV main element and TMD materials,this paper calculate the coupling mechanism between the two materials and the metal substrate and the influence of defects,providing important reference value for the experimental preparation of large-scale and high-quality two-dimensional materials.Applying the principle of first principles,it is pointed out that the magnetic properties of monolayer molybdenum disulfide?MoS2?are regulated by the method of defect engineering.The extensive structural defects in single-layer MoS2 samples pose a greater threat to material properties.In this paper,the effects of different types of grain boundary and antisite defects on energy stability and electromagnetic properties in single-layer MoS2 are systematically studied.It was found that the stability and magnetic properties of the defect single layer are closely related to the number and type of chemical bonds of the same element.One of the types of unsaturated bonds constitutes a ferromagnetic grain boundary with a magnetic moment of up to 1.10 ?B/nm.The grain boundary structure composed of the same number of Mo-Mo bonds and S-S bonds exhibits antiferromagnetic properties.In addition,the introduction of antisite defects in the grain boundaries can improve the stability of the system and have little effect on the original magnetism.The use of defect engineering methods to control the magnetic properties of single-layer TMD provides a new way for experimental workers.Considering the practical application of TMD in field effect transistors?FETs?,combined with fir-st-principles calculations and quantum transport simulations,we studied the contact characteristics of bismuth disulfide?ReS2?and a series of metal electrode materials?silicene,borophene,Al,Ni,Cu metal and Ti3C2,Hf3C2 transition metal carbide?,it is clear that these electrode materials form a n-type Schottky contact with a single layer of ReS2.Through the calculation of binding energy and electronic properties,we found that the coupling strength of different systems is different.Among them,the strong interfacial interaction between Ti3C2 and Hf3C2 electrodes and single-layer ReS2 and relatively low work function can form an ohmic contact with ReS2.These theoretical studies have facilitated the experimental synthesis of high-performance electronic devices consisting of ReS2.As an extension of the single-layer TMD material,we also systematically studied the interfacial coupling mechanism of silicene,germanene,stanene and common metal substrates in the single-layer material of the ? main group.Different from the sp2 hybridization of carbon atoms in graphene,Si,Ge,and Sn are more inclined to sp3.Therefore,selecting a suitable metal substrate to stabilize the above materials is a prerequisite for synthesizing high-quality two-dimensional single-layer materials.By simulating the scanning tunneling microscope?STM?image and calculating the differential charge density and the local electronic state density,it is found that a moderate interaction intensity of 0.6-0.7 eV/atom is beneficial to the growth of high quality silicene and germanene.Accordingly,we predict that the Al?111?surface may be suitable for epitaxially growing low buckled two-dimensional stanene.In addition,combined with the experimental data,we found that the stanene grown on the Au?111?substrate has a large tensile strain due to the strong interaction between the stanene and Au substrate interfaces.On the other hand,a large tensile strain can significantly enhance the electron phonon coupling.When the Sn coverage is low,the Sn-Au surface alloy is first formed.As the coverage of Sn atoms increases,a3^1/2×7^1/2phase stanene superstructure is finally formed.The Raman spectrum of the experiment and the first-principles calculation of the dynamic density of the vibration indicate that the unique phonon vibration mode of the3^1/2×7^1/2phase stanene is closely related to the tensile strain.The combination of our theoretical and experimental results provides important guidance for studying the peculiar properties of strained two-dimensional materials.