Fabrication And Performance Optimization Of Molybdenum Disulfide Based Field Effect Transistor

In recent years,two-dimensional semiconductor atomic crystal materials have attracted extensive research attention due to their unique properties and wide application prospects.Molybdenum disulfide(MoS₂),as a typical material in two-dimensional materials,has a broad application prospect in electronic devices,photoelectric devices,sensors and energy devices due to its band gap varying with the number of layers,atomic-level surface flatness,stability and high surface-area-volume ratio.However,in MoS₂ MOSFET,impurities and Fermi Level Pinning effect at the MoS₂/metal contact interface severely limit device performance.Therefore,it is of great significance to optimize the fabrication process and study the contact characteristics of MoS₂ devices.In this paper,it is proposed to improve the interface contact condition of MoS₂ by oxygen plasma treatment,aiming at the problem that the impurities introduced in the fabrication of MoS₂ and its devices will have a serious impact on performance.The fabrication technology of high performance MoS₂ devices was studied by means of photoelectron spectroscopy,and the effect of oxygen plasma on the properties of MoS₂ materials and the mechanism of action were analyzed.Finally,device performance is improved.The main conclusions are as follows:(1)The physical and chemical states of molybdenum disulfide surface are changed by oxygen plasma treatment.With the increase of treatment time,the surface roughness of monolayer MoS₂ prepared by chemical vapor deposition method also increased,from 0.37nm to 1.10 nm after 30 s treatment.Oxygen plasma can oxidize the top layer of MoS₂,and the generated MoO₃ can protect the lower m MoS₂ from being etched and oxidized,but it cannot prevent oxygen ions from being inserted into the lower MoS₂ lattice,thus affecting its lattice vibration.(2)The surface treatment of MoS₂ in contact area by oxygen plasma can improve the performance of MoS₂ transistor.After oxygen plasma treatment,the surface roughness of the contact interface was reduced from 0.53 nm to 0.17 nm,which effectively removed the organic impurities on the interface and reduced the carrier scattering degree of the impurities at the interface.The MoO₃ generated by oxygen plasma oxidation of surface MoS₂ forms a tunneling layer at MoS₂/metal interface and eliminates the Fermi Level Pinning effect,thus greatly improving the performance of the device.(3)Oxygen plasma treatment can form p-type doping of the channel,and the doping comes from the insertion of oxygen ions in the lattice of MoS₂.When the channel is thick,the scattering of impurities on the channel surface to carriers is the main factor affecting the performance of the device.When the channel is thin,the doping of oxygen ions on the channel becomes the main factor affecting the performance of the device,and the p-type doping degree of the device is related to the processing time.