Study On Metal Contact Characteristics Of Layered Molybdenum Disulfide Film

Transition metal dihaloalkanes（TMDC）have attracted much attention due to their excellent properties and two-dimensional layered structure.Because of its ultra-thin,no hanging key and adjustable band gap,it has potential applications in the neighborhood of electronic science.To obtain high performance molybdenum disulfide devices,it is necessary to achieve good contact between the metal electrode and molybdenum disulfide.However,due to the large Schottky barrier between the metal electrode and molybdenum disulfide,the carrier injection efficiency is limited,the contact resistance increases,which affects the performance of the device and increases the useless power consumption.So it is very important to realize ohmic contact between metal and molybdenum disulfide.In general,the molybdenum sulfide prepared by CVD has n-type conductivity.It is an urgent problem for device and circuit applications to dope it effectively and obtain good p-type molybdenum disulfide metal semiconductor contact characteristics.In this paper,molybdenum disulfide films were prepared by CVD method,and doped effectively by plasma technology.The contact characteristics between different metals and p-type molybdenum disulfide films were studied,which laid a foundation for circuit application.The process of preparing Mo S₂thin film by CVD was optimized.The n-type Mo S2 thin film was analyzed by Raman spectrum and pl.the results show that the position of A_1gvibration mode is383.6cm^-1,the position of E_2gvibration mode is 404.2cm^-1,the difference between the two peaks is683.44nm（1.8e V）in PL spectrum.The position of A_1gmode and E_2gmode was 382.8cm^-1and405.8cm^-1,respectively.The difference between the two peaks increased to 22.97cm^-1and PL peak shifted to the right.The results show that the doped molybdenum disulfide is p-type.The Ti,Cr,Al,Ni metal electrodes were prepared by photolithography and electron beam evaporation.The test results show that the contact I-V curve of metal with n-type molybdenum disulfide is nonlinear and has obvious rectifying characteristics,while the contact I-V curve with p-type molybdenum disulfide is linear and ohmic contact is obtained.The contact characteristics of titanium,chromium,aluminum and nickel with molybdenum disulfide were studied.MS structure was prepared and I-V characteristics of MS structure were measured.The results show that the difference of metal semiconductor work function has a significant effect on the I-V curve.The contact resistance of Cr/Au is the smallest,Ti/Au is the second,and Ni and Al are the largest.When chromium/gold and titanium/gold are in contact with molybdenum disulfide,the contact characteristics are close to ohmic contact.This is of great significance to optimize the interface contact characteristics between metal and p-type molybdenum disulfide,reduce the contact resistance,achieve good ohmic contact and build a circuit based on molybdenum disulfide.