| Layered MoS2is a material with adjustable band gap and graphene-like layered structure.It is a research hotspot of layered materials and has great potential for applications in electronic devices and lubrication.However,the preparation method and process of large-area continuous layered MoS2films are still immature and have important research significance.In this thesis,continuous layered MoS2films were prepared by two methods:magnetron sputtering combined with annealing and two-step sulfurization,and the preparation conditions and characteristics of the films were studied.Continuous multilayer MoS2films were prepared by magnetron sputtering and annealing.Firstly,the effects of work pressure and sputtering power on the preparation of as-grown MoS2films were studied,and the optimal process conditions 1.0 Pa and 30 W were obtained.The surface of the as-grown films prepared under this condition is smooth and compact with a high deposition rate.Then,the effect of annealing temperature on the preparation of layered MoS2films was studied.With the increase of temperature,the film gradually changed to a continuous film state,and the crystallinity also increased.When the annealing temperature is 950°C,a continuous MoS2film with good crystallinity is formed,and the FWHM of the X-ray diffraction peak is only 0.384°.The Raman shift difference of the continuous film is about 26 cm-1,which indicates that the prepared film is multi-layered,and the multilayer structure leads to the weakening of the light-emitting characteristics of the film.The two-step sulfurization method was used to prepare a continuous layer of MoS2film.Firstly,molybdenum films were prepared by electron beam evaporation,and the effect of evaporation time on the deposition rate and surface morphology of the molybdenum film was studied.As the evaporation time increases,the average deposition rate of the molybdenum film increases,and the surface becomes more compact and the roughness decreases.The reason is that increasing the evaporation time will increase the temperature of the substrate and enhance the ability of particles to migrate and diffuse,which is conducive to the formation of compact films.To prevent pressure changes from affecting the results,as the evaporation time increases,the electron beam current must also be appropriately increased.This will increase the energy of the evaporated particles,which will help reduce the loss of particles before they reach the substrate,thereby increasing the average deposition rate of the molybdenum film.Then,continuous few-layer MoS2films were prepared by CVD.The effects of reaction temperature,thickness of Mo film and surface impurities on the growth of MoS2films were studied.Due to the high temperature required for the reaction,the molybdenum film will be evaporated during the reaction.When the molybdenum film on the sapphire substrate is about 10 nm,triangular MoS2crystal domains will be formed due to the evaporation of molybdenum after sulfurization.When the reaction temperature is low,the crystal domain size is large,and the film has good continuity;when the reaction temperature is high,the crystal domain size is small,and the film is poor in continuity.MoS2film with two layers and good continuity was obtained at 600°C.Increasing the thickness of the molybdenum film can make up for the loss of evaporation and meet the needs of the reaction,thereby forming continuous few-layer MoS2films.When the thickness of the molybdenum film is about 20 nm,a continuous few-layer MoS2film with significantly reduced number of crystal domains is obtained.Impurities exist on the surface of the film,and multilayer or bulk MoS2domains and crystal grains are generated at the positions of the surface impurities and around them,which is not conducive to the growth of continuous few-layer MoS2 films. |
