Halide-assisted Preparation And Application Properties Of Two-dimensional Tungsten Disulfide/Tungsten Diselenide

Two-dimensional transition metal chalcogenides not only possess the excellent properties shared by two-dimensional materials,but also have adjustable direct bandgap,flexibility,and high optical transparency.The applications of the fields have broad prospects in solid-state nanodevices,optoelectronics,sensing and functional films and so on.However,how to prepare high-quality and large-area two-dimensional transition metal chalcogenides simply and efficiently has been restricting the research process in this field.Chemical Vapor Deposition is a universally recognized method for industrial production the two-dimensional material on the solid substrate.Therefore,it is of great significance to study chemical vapor deposition to prepare two-dimensional transition metal chalcogenides.The tungsten oxide used for preparing two dimensional tungsten disulfide and tungsten diselenide is too low vapor pressure and difficult to vaporization.High temperature or ultra-low pressure is often required in experiment,which is a key problem to be solved in the related fields.In this dissertation,two dimensional tungsten disulfide and tungsten diselenide were selected as research objects.The large size and high quality target materials were successfully prepared by the halide-assisted chemical vapor deposition method.In this dissertation,we mainly explored the effects of experimental growth temperature and time,halide species and addition ratio,and carrier gas flow rate on material preparation.Large size and high quality tungsten disulfide and tungsten diselenide was prepared on the silicon dioxide substrate at relatively low temperature and mild experimental conditions.In this dissertation we use various characterization methods to determine the material has very good quality,such as Optical Microscope,Scanning Electron Microscope,Raman spectra,Photoluminescence spectroscopy,Transmission Electron Microscope,Atomic force microscope and so on.Through a series of experiments,we explored the mechanism of the preparation method and gave a more reasonable explanation.The PVA transfer technology was used to transfer the target material and the field effect transistor was constructed to check the electrical performances of the material.