Preparation And Optical Properties Of Two-dimensional MoS₂/Bi₂Se₃ Heterostructure

In recent years,as graphene-like materials have emerged as the most likely alter-native to silicon-based semiconductors,more and more researchers have devoted themselves in this field.Among those materials,monolayer MoS₂has a direct band gap of about 1.85 eV,and Bi₂Se₃can produce topological and non-topological phase transition at 5 layers and below,thus showing special physical and chemical properties.Scholars have carried out in depth and systematic studies on the preparation methods,energy band structure,photoelectric properties,sensing properties,interface effects,catalytic properties of the two materials.It has been proved that MoS₂has great application potential in transistors,photodetectors,sensors,batteries and other fields.Bi₂Se₃has great potential in semiconductor detectors and spin quantum devices.In this paper,based on the current research status of graphene like molybdenum disulfide and bismuth selenide and the development prospect of van der Waals heterostructure,we focus on the preparation and growth mechanism of large-area,high-quality,continuous MoS₂and Bi₂Se₃thin films,the preparation method of MoS₂/Bi₂Se₃heterostructure,and their optical and photoluminescence properties.This paper mainly covers the following aspects:1.The growth conditions of MoS₂and Bi₂Se₃were systematically studied by controlling the growth temperature,growth area and carrier gas flow rate in the vapor deposition method.MoS₂/Bi₂Se₃heterostructure was successfully prepared by PS（Polystyrene）transfer method.Optical microscopy,AFM（Atomic Force Microscope）,SEM（Scanning Electron Microscope）,SHG（Second Harmonic Generation）,and Raman spectroscopy were used to detect the thickness,flatness and interface coupling quality of the heterostructure.The results show that the two materials of the heterostructure have good flatness after stacking,and the transfer method used is efficient and non-pollution.No additional stress was introduced when the two materials were stacked,and the obtained heterostructures show good interfacial coupling quality.2.The exciton luminescence,interfacial interaction and charge transfer in the two heterostructure were studied by photoluminescence（PL）.It was found that PL was significantly enhanced in the MoS₂/Bi₂Se₃heterostructure based on 5-layer Bi₂Se₃.However,PL of MoS₂/Bi₂Se₃heterostructure based on Bi₂Se₃with more than5 layers is obviously weakened.The results show that the surface state of two-dimensional Bi₂Se₃,which varies with the number of layers,has a significant modulation effect on the optical properties of MoS₂.