Preparation Of Two Dimensional Materials At Low Temperature

The discovery of graphene filled a blank space in the field of two-dimensional materials.It has long been viewed as an ideal material for flexible electronic device because of its excellent electrical,mechanical,optical and other properties,due to its special atomic structure.It has become a research hotspot of many researchers and has aroused the research boom of academics.At the same time,it has also promoted the discovery and preparation of other two-dimensional materials.For example,the molybdenum disulfide,the relatively mature study in tansition metal dichalcogenide materials,is widely used in electronic device field such as transistors because of its wide band gap.In recent years,the preparation of two-dimensional materials has been rapidly developed.Mechanical exfoliation,liquid-phase exfoliation and chemical vapor deposition(CVD)is the main synthetic methods of two-dimensional materials.Among them,chemical vapor deposition is concerned by many researchers in the field of twodimensional materials because of its relatively low production cost and convenient operation.However,this method requires high temperature condition,which is a big limitation for industrial production,so further development methods are needed to reduce the temperature required to meet the requirement of industrial production.In this paper,a monolayer graphene film is synthesized on a copper substrate by plasma enhanced chemical vapor deposition(PECVD).The plasma is used to activate the reaction precursors at normal atmospheric temperature,and then deposited at a lower reaction temperature to form a graphene film.Meanwhile,the shielding effect of the copper tube is used to reduce the ions bombardment effect on the formed graphene film caused by plasma to make the defects of graphene film much less and effectively suppresses the growth in the vertical direction,thereby a uniform continuous large area monolayer graphene film could be synthesized at a low temperature.In addition,we investigated the effects of hydrogen flow rate,copper substrate position,presence or absence of copper tube,reaction temperature and excitation power on the quality of graphene,then discussed the mechanism of synthesizing graphene films at low temperature.We also have studied the preparation of molybdenum disulfide at low temperature using molten salt-assisted atmospheric pressure chemical vapor deposition,and it was found that the domains of the molybdenum disulfide in the edge regions silicon wafer with low nucleation density and small number of layers were larger than that of the directly deposited region.By investigating the influence of the mass of molybdenum trioxide and sodium chloride and the flow rate of carrier gas on the growth results,a monolayer of molybdenum disulfide with a crystal domain of about 400?m was synthesized.Then,the mechanism of synthesizing large crystalline domains of molybdenum was described,which could provide ideas for further synthesis of continuous monolayer molybdenum disulfide.