Studies On The Property Modulation Of Monolayer MoSe₂

With the development of modern technology,the material without artificial modulation often cannot exhibit versatile applications.Therefore,the flexible tuning of materials with various excellent properties has become a research hotspot.Since the discovery of two-dimensional materials,researchers have paid much attention to their remarkable electrical and optical properties due to their special structure.Two-dimensional Transition metal dichalcogenides（TMDs）is now playing increasingly important roles.In this paper,we select typical TMDs materials MoSe₂,and study its electronic properties.Aim to lay a foundation for the subsequent study on its application,we use Pt element to modulate its electronic structure through adsorption and alloying.Moreover,in cooperation with the experimental work of rare earth element Ce（Lu）substituted transition metal element doped monolayer WS₂（MoS₂）,the modulation of rare earth element introduction on its properties was studied by means of first-principles,which provided a theoretical basis for the experiment.The main work of this paper is as follows:In this paper,we prepare the monolayer MoSe₂ film by molecular beam epitaxy and the growth conditions of MoSe₂ was discussed.Further,the precious metal Pt element,which has application potential in catalysis and other aspects,was introduced into the film to adjust its electronic structure by adsorption and alloying.The pattern selective adsorption of Pt clusters on MoSe₂ line defects was successfully achieved.And Mo_xPt_1-xSe₂ monolayer alloy film was successfully prepared.The modulation of MoSe₂ electronic structure by the introduction of Pt element was studied by scanning tunneling microscopy and scanning tunneling spectroscopy,which laid a foundation for the subsequent research of TMDs.Moreover,the structural model of monolayer of WS₂（MoS₂）doped with rare earth Ce（Lu）substitution transition metal element is constructed.The effects of Ce on the electronic structure of WS₂ and Lu on the MoS₂ are studied by first principles calculation.The change of band structure is due to lattice distortion caused by doping and the introduction of multiple additional electronic states by doping elements are confirmed.The introduction of Ce element in monolayer WS₂ may lead to the transition from direct band gap to indirect,and the introduction of Lu element in MoS₂ may lead to a large change in the conduction band bottom,which provides assistance and theoretical reference for experimental.