CVD Preparation Of Two-dimensional Molybdenum Disulfide And The Study Of The Effect Of Strain On Raman Signal Of Two-dimensional Materials

As a typical representative of two-dimensional materials,graphene has attracted the interest of many scientists due to its special structure and physical and chemical properties.However,its zero-band gap characteristics limit its application field.As the most typical transition metal sulfur compound,molybdenum disulfide has good thermal and chemical stability,high mechanical strength,high flexibility,high transparency and high carrier mobility.Monolayer molybdenum disulfide is a direct bandgap semiconductor with extremely superior photoelectric characteristics and ultra-high device switching ratio,which makes it an ideal material for building the next generation of lighter,thinner,faster and more sensitive electronics and optoelectronics devices.In this paper,molybdenum disulfide was prepared by conventional atmospheric pressure CVD method,and the obtained samples showed the coexistence of onedimensional nanometer points,two-dimensional(or low-dimensional)films and threedimensional materials,which could not be distinguished from each other.These results show that the samples can not be further used in device synthesis.As an improvement,this paper adopts the method of double substrate superposition to realize nucleation and agglomeration of high temperature plasma in a narrow space within two substrates through a long reaction time.The experiment focused on the surface modification and pretreatment of the substrate.Through several experiments,it was found that the substrate treated by piranha solution was covered with OCA adhesive tape,so as to realize the distribution of dispersed seed layer and obtain high-quality two-dimensional molybdenum sulfide more easily.The results show that the molybdenum disulfide grown has reached a monolayer,and the transverse scale can reach millimeter in the specific area of the sample.In addition,the paper introduces the properties and applications of molybdenum disulfide in three dimensions,and explains the common characterization methods of nanometer materials and the preparation methods of layered molybdenum disulfide.Based on the previous calculation,the regulation of the electronic structure of molybdenum disulfide under different types of stress is summarized,and the strain mode of a new two-dimensional material,arsenate,and the Raman spectral changes during the strain process are derived by using functional density theory,normal form conservation pseudopotentials and gradient approximation.