| Two dimensional transition metal sulfide(MS2)is a kind of lamellar material with single/multi atom thickness.Its excellent physical,chemical,optical,electronic and mechanical properties have attracted extensive attention in the field of science.MoS2 and WS2,as two-dimensional materials discovered earlier,have stronger research potential than graphene in optoelectronic applications,while Pt S2 has less related research,showing great potential in optoelectronic field.However,due to the limitations of current preparation methods and technologies,these two-dimensional materials have low production efficiency,large fluctuation of quality level,and high cost,so it is difficult to realize their comprehensive application in all fields.Under this background,we have successfully prepared large area and high quality continuous MS2 thin films of over 100?m by chemical vapor deposition using metal oxide source and metal source as precursors,and tested the optical and electrical properties of the films.The main results are as follow:(1)We prepared large area MoS2 films by MoO3 powder source.The effects of heating temperature of molybdenum source,heating temperature of sulfur source,distance between substrate and molybdenum source,quality of molybdenum source,growth time,flow rate of argon and concentration of halide solution on the preparation of MoS2 films by CVD were systematically studied.Then,we fabricated MoS2 thin film transistor(MoS2-TFT)by surface treatment,photolithography,coating and thermal annealing.The electrical properties of MoS2-TFT were tested.The results show that the MoS2-TFT device has a high gate voltage tunability with a carrier transfer rate of 0.032 cm2·V-1·S-1 and a switching ratio of 4×104.(2)We prepared large area WS2 films by WO3powder source.The effects of gas source type,heating temperature and growth time on WS2 films prepared by CVD were systematically studied.The optimum experimental conditions were obtained as follows:Ar/H2(5%H2)mixture,850?,15 min.The higher the temperature is,the weaker the peak intensity is,and the greater the red shift of the peak position is.After further heating,the luminescence intensity of WS2 at low temperature is significantly higher than that without heating,which shows the excellent optical properties of WS2on high-k gate dielectric Sr TiO3,and analyzes the influence mechanism of low temperature on the photoluminescence of WS2 on high-k gate dielectric Sr TiO3.(3)We prepared large area continuous MoS2 thin films by direct sulfurization with metal Mo source.The effects of heat treatment with or withoutO2 and heating temperature of Mo source on the preparation of MoS2 thin films by CVD were systematically studied.The MoS2 film withO2 heat treatment is more continuous,which can effectively reduce the appearance of irregular morphology.The optimum heating temperature of molybdenum source is 650?.(4)Platinum films with different thickness were pre deposited on Si/SiO2substrates,and large area continuous Pt S2 films were successfully prepared by direct sulfurization.The films were characterized by optical microscopy,Raman spectroscopy,scanning electron microscopy and atomic force microscopy.Then Pt S2thin film transistors were fabricated,and the electrical properties of Pt S2 thin film transistors with different thickness were tested.(5)Large area continuous monolayer MoS2 thin films can be successfully prepared by confined space method using metal Mo source as precursor.The optimum experimental conditions are as follows:the number of auxiliary substrates is three(1.56 cm),the heating temperature of molybdenum source is 750?,the pressure is 7.5×104 Pa,the temperature of s temperature region is 260?,and the gas flow rate is 80 sccm.MoS2 thin film transistors(MoS2-TFT)with bottom gate top contact were fabricated by surface treatment,photolithography,coating and thermal annealing.The electrical properties of MoS2-TFT were tested.The carrier mobility of MoS2-TFT was 0.043 cm2·V-1·S-1and the switching ratio is 105,which is higher than MoS2 thin films from powder source,and the gate voltage is more adjustable. |
PDF Full Text Request