First-principle Study Of Electronic Structure Of Surface Adsorptive Monolayer MoS₂ And Phosphorene

Molybdenum disulphide?MoS₂?, as a new-type transition metal compound, due to its excellent thermal stability and chemical stability, has been widely used in solid lubricant, reaction catalyst and electrode materials, etc. Monolayer MoS₂ as graphene-like transition metal compound, on account of its excellent electrical properties, is widely utilized and explored in transistor manufacture and the application of diluted magnetic semiconductor etc. At the same time, the properties such as high surface-to-volume ratio and semiconducting properties have also accelerated the development and application of monolayer MoS₂ as the chemical sensors. In recent years, it has been found that black phosphate is another new type of semiconductor materials following MoS₂. It has higher application potential owing to its high mobility and conductivity anisotropy in nanoelectronics, optoelectronic and other fields etc. This thesis, based on the density functional theory of VASP calculation software, systematically studied the electronic structure properties of MoS₂ and black phosphate. Research work mainly focused on the following three areas:?1? The electrical properties of pure and defective monolayer MoS₂ are investigated in aspect of the adsorption of volatile organic compounds before and after. The volatile organic compound is physical adsorption with the purity and S vacancy of MoS₂ substrate. The impurity level appeared in the band gap of MoS₂ after the adsorption of organic molecules, as well as showing the p type or n type doping property.?2? The electrical and magnetic properties of the different concentrations of the metal functional defects MoS₂ before and after the adsorption of volatile organic compounds are investigated. The volatile organic compound is chemical adsorption with the metal functional S vacancy of MoS₂ substrate. The band gap of MoS₂ further reduces and the number of the conduction band and valence band are increased significantly. The adsorption of volatile organic compounds in different metal atoms functionalization MoS₂ has a influence of magnetic moment. The magnetic moment is mainly focused on the doping of metal atoms. For adsorption system, Fe of ferromagnetic exchange can be the most stable.?3? The electronic properties of black phosphorus and carbon nanotube?BP-CNT? heterojunction are investigated. The carbon nanotubes are physical adsorption with black phosphorus. However, they formed a stable chemical adsorption after mixing the metal atoms, showing higher binding energy. The band gap value reduce after the adsorption of carbon nanotubes by black phosphorus. The introduction of the metal atoms makes the BP-CNT have magnetism. The BP-CNT heterojunction doped with Fe atoms shows ferromagnetism and doped with Co atoms shows antiferromagnetic.