Research On Design And Preparation Of MoS₂ Lateral P-N Homojunctions Photodetector

In recent years,two-dimensional transition metal chalcogenides（TMDCs）have attracted much attention due to their atomic thickness and excellent electrical and optical properties.Molybdenum disulfide（MoS₂）,one of the most widely studied TMDCs,is an ideal material in photodetector due to its high carrier mobility,optical absorption properties and adjustable band gap.PN junction is the basic structure in photodiode.Doping technology is the key to preparing high-performance PN junctions.The layout of lateral p-n homojunctions photodiode was design by L-edit.It includes field effect transistors and PN junctions with different channel lengths,bipolar junction transistor with different base widths and amplifier circuits connecting the PN junctions and NPN Transistor.In addition,the accuracy of the alignment marks has been optimized in the layout design.MoS₂ films were prepared by using the optimized parameters of CVD.The difference of peak value of₁₂)and¹₂₂)in Raman spectrum is 18.09 cm^-1 and the peak of PL spectrum is located at 683.23nm（1.81e V）.The thickness of the MoS₂ measured by AFM is0.68 nm.Therefore,the MoS₂ films we prepared are monolayer.After the steps of photolithography,nitrogen plasma doping and electron beam evaporation,the lateral p-n homojunctions photodiode and amplifying circuit based on MoS₂ were prepared.the rectification ratio of lateral p-n homojunctions is 10².When the reverse bias voltage is 10V,the ratio of the photocurrent to the dark current of the lateral p-n homojunctions photodiode is above 10²,and the photoresponsivity is 4.85A/W,response time is 0.02s.furthermore,the current of the photodiode can be amplified 100 times by the bipolar transistor.In this paper,nitrogen plasma is used to achieve selective doping of MoS₂,and MoS₂lateral homojunction photodetectors are prepared,which provides useful exploration for the design and preparation of two-dimensional transition metal chalcogenide lateral homojunction devices and circuits.