Fabrication And Performance Study Of Junction Type Field Effect Transistor Of Molybdenum Sulfide

In recent years,Two-dimensional(2D)transition metal dichalcogenides(TMDCs)have become a research hotspot at home and abroad due to their extremely thin size,natural band gap and excellent photoelectric properties.Molybdenum sulfide(Mo S₂)is one of the most typical TMDCs,with its high mobility,high transparency,excellent mechanical ductility and photoelectric properties,which has attracted extensive attention in many fields.Therefore,it is of great significance to prepare high quality and large size molybdenum sulfide films and field effect tubes with excellent properties..In this paper,the forming energy of N⁺and N₂⁺ion doped Mo S₂is calculated,and the feasibility of doping is verified by theoretical calculation.The first principle is used to calculate the energy band diagram and state density diagram of the stable structure of Nitrogen-doped Mo S₂,and the p-type conductive characteristic of the nitrogen-doped Mo S₂film is obtained.In order to verify whether the molybdenum sulfide PN junction with this structure has good rectification characteristics,Scaps software was used to establish the molybdenum sulfide PN junction model to calculate the I-V characteristic curve,and it was found that the molybdenum sulfide PN junction has good rectification characteristics.Based on chemical vapor deposition(CVD),the"reverse reaction method"was proposed to prepare the molybdenum sulfide film,and the temperature parameters were optimized.The size and quality of the film were larger.Molybdenum sulfide homogeneous junction type field effect transistor(JFET)was prepared by micro-nano processing technology,and the molybdenum sulfide film was characterized by AFM,Raman and PL spectra,proving that the prepared molybdenum sulfide film was less layered and the molybdenum sulfide film after nitrogen doping was the electrical characteristics of P type.The electrical properties of the prepared molybdenum sulfide homogeneous junction were tested and analyzed,and it was found that the junction had better rectifier properties.The above characterization and test results are also verified with the previous simulation calculation.Finally,several molybdenum sulfide homogeneous junction devices were tested and analyzed:(1)the output current Ids of molybdenum sulfide homogeneous junction JFET with Ti/Au electrode was small,which was related to the ohmic contact between metal electrode and molybdenum sulfide film and the influence of nitrogen plasma doping.Its electron mobility=0.387cm²/Vs and threshold voltage is about 13V.(2)The output current Ids of JFET with Cr/Au as electrode is 10²larger than that with Ti/Au as electrode,with electron mobility=24.554cm²/Vs and threshold voltage of about 5V.Both the mobility and the output current are much higher,because Cr has a strong interaction with molybdenum sulfide,so the contact resistance is much lower.(3)The effect of annealing process on JFET properties of molybdenum sulfide homogeneous junction was studied.The characteristic curve of JFET in the doped molybdenum sulfide homojunction with annealing process was tested,and the electron mobility was calculated as=69.940cm²/Vs.The threshold voltage was about 13V,and the mobility was much larger than that of the devices without annealing process.Because of annealing process,the molybdenum sulfide film can be recrystallized to repair the damaged molybdenum sulfide lattice.