Study On Synthesis And Photoelectric Properties Of Two-dimensional Transition Metal Chalcogenides

Since graphene and graphene-like transition metal dichacogenides are discovered,they have set off a wave of research at home and abroad because of their unique optical,mechanical,thermal,and electrical properties.However,the zero band gap of graphene limites its application in the field of electronic devices,as a representative of two-dimensional transition metal dichacogenides,single-layer tungsten disulfide?WS₂? not only possesses the high mechanical strength and high electron mobility,but also the direct band gap width of 2.1eV of single layer WS₂ overcomes the disadvantage of zero band gap of graphene,which makes it have a broad application prospect in the field of electronics.The preparation of WS₂ is the premise and basis for expanding its application,and it is one of the current research hotspots.In this thesis,a single layer WS₂ is prepared by chemical vapor deposition?CVD?method,and it is studied by optical microscopy,Raman spectrometer,and photoluminescence spectroscopy.The main research contents are:?1?WS₂ was prepared on a SiO₂/Sisubstrate by atmospheric pressure chemical vapor deposition method,and discussed separately from five growth parameters of gas flow rate,sulfur quality,tungsten trioxide quality,growth temperature,and distance between precursor.The influence of the preparation on the product obtained and the morphology of the prepared product were analyzed,and the growth parameters were continuously optimized to obtain the conditions for the preparation of single layer and regular-shaped triangular WS₂ films.?2?The single layer WS₂ thin film prepared by CVD was annealed.Firstly,it is annealed in a vacuum environment,and then the WS₂ annealed at different temperatures was characterized by photoluminescence,scanning electron microscopy and Raman spectroscopy,finally,it was found by analysis that annealing at a temperature of 300? can cause the fluorescence intensity enhancement several times,indicating that annealing can improve the optical performance of the single layer WS₂ film to a certain extent.?3?A single layer WS₂ thin film device based on CVD was prepared by laser direct writing technology and the electrical and optical characteristics of the WS₂ thin film device were studied.The output curve and transfer curve of the WS₂ thin film device were tested,the graph analysis showed that the thin film device has N-type and excellent gate control characteristics,at the same time,under the irradiation of the laser,it was found that the WS₂ thin film device have a photocurrent generation,and the light response time was obtained from the light response curve of the device,that shows that the WS₂ thin film device has excellent photoelectric properties.