Fabrication And Photodetection Application Of Molybdenum Sulfide Bipolar Junction Transistor

In recent years,transition metal chalcogenides(TMDCs)have become one of the research hotspots at home and abroad.These materials have the advantages of two-dimensional layered structure and adjustable band gap,and have broad application prospects in the fields of optoelectronics and integrated circuits.As a typical representative of transition metal chalcogenides,molybdenum disulfide not only possesses all the advantages of TMDCs,but also has high carrier mobility,which has attracted the attention of researchers.PN junction is the basic structure that composes various devices and circuits,but the preparation of excellent performance PN junction requires good film preparation technology and effective doping technology,which is also the current research focus of two-dimensional semiconductor materials.In this paper,we have conducted in-depth research on the large-area fabrication and effective doping of molybdenum disulfide,adjusted and optimized the process parameters of the fabrication of the film,and successfully prepared a large-area and continuous molybdenum disulfide film.The films were characterized and analyzed by Raman spectroscopy,photoluminescence and atomic force microscopy.In the Raman spectrum,the characteristic peak¹₂₂)of the film is located at 382.51 cm^-1,and the characteristic peak₁₂)is located at 403.94 cm^-1.In the PL spectrum,the peak is located at 682.31nm,and there are no multiple peaks,indicating that the prepared film is a single-layer molybdenum disulfide film.The AFM characterization results show that the uniformity of the film is good,and the film thickness is 0.7nm.In this paper,oxygen plasma is used for area-selective doping of the thin film,PN junction and PNP bipolar transistor structure are constructed on the thin film,and lateral homojunction and PNP bipolar transistor based on molybdenum disulfide film are successfully fabricated.The volt-ampere characteristic curve of the lateral homojunction shows that its rectification ratio reaches 10³,which indicates good PN junction rectification characteristics and effective doping effect.PNP-type bipolar transistors are constructed in the experiment.The bipolar transistors have obvious amplification characteristics in common-base connection and common-emitter connection.The maximum of common-base current gain(?)is 0.98,and the maximum of common-emitter current gain(?)is 750.The lateral homojunction can be used for photoelectric detection.The results show that the light responsivity is 47.55A/W,the response rising edge time is 0.1s,the response falling edge time is 0.04s,and the photodetection rate is 1.4×10¹⁰Jones.