First-Principles Study Of The Physical Properties Of Two-Dimensional Chalcogenides

Two-dimensional materials have attracted the attention of researchers for some time because of their unique physical and chemical properties and potential applications.In recent years,researchers have gradually enriched the two-dimensional material system and made their families to grow and develop.The transition metal chalcogenide,such as MoS2 and WS2,are important members of the two-dimensional material family.Studies have shown that doping some atoms into the two-dimensional MoS₂ can change some properties of the two-dimensional MoS2,but in the research they often neglect the semiconductor properties that are destroyed after doping,which limits the application of materials.Therefore,it is of great significance to control the related properties of materials by doping.This thesis used the first-principles calculation method based on density functional theory to calculate the two-dimensional MoS₂ and WS₂ supercell models of3?3?1.The calculation of the model showed that pure MoS₂ and WS₂ have good semiconductor properties,and no magnetic.By doping Mn,Fe,and Co atoms in the MoS2 and WS2,the system can obtain magnetic properties.However,the doping destroyed the semiconductor structure of the system and exhibited half-metallic properties.We also analyzed and compared the MoS2 and WS2systems doped by Mn,Fe,and Co atoms.Next,the thesis also studied the physical properties by doping non-magnetic atoms C,Si and Ge in WS2.Such WS2 system doped with C,Si and Ge can show the characteristics of a good narrow band gap two-dimensional material,but the system introduces impurity energy levels.Through analysis,we have selected Si and Mn atoms to doped in WS2.The doped system showed good semiconductor characteristics and magnetic properties.In addition,we also selected N and Fe to dope in WS2,which showed the half-metal properties by doping.And a semiconductor material with magnetic properties was obtained.