Study On The Electromechanical Properties Of Molybdenum Disulfide Layered Materials Based On Atomic Force Microscope

Ultrathin two-dimensional nanomaterials have broad application prospects in materials science,physics,chemistry and nanotechnology.Recent advances in the characterization of nanomaterials by atomic force microscopy have opened up new opportunities for the study of two-dimensional nanomaterials in the field of microelectronics and optoelectronics.Molybdenum disulfide?MoS₂?is a kind of material with layered structure.When it is made into monolayer material,it shows great physical properties different from bulk material.At present,MoS₂ has been used in a variety of devices,but few reports have studied its electromechanical performance from the microscopic point of view.This work is based on the atomic force microscope with a variety of modes in the study of materials,for the MoS₂ two-dimensional nanomaterial electrical and mechanical properties of characterization.Mainly through scanning kelvin probe microscopy,conductive atomic force microscope and bimodal atomic force microscopy study the electrical properties of MoS₂ in MoS₂/Si O2?MoS₂/Pt and MoS₂/Ba Ti O3 heterojunction,the electrical transport properties of MoS₂ in MoS₂/Pt heterojunction,the mechanics performance of MoS₂ in MoS₂/Si O2,MoS₂/Pt and MoS₂/Ba Ti O3 heterojunction,for research in micro-scale MoS₂ electromechanical properties to provide the experimental data.The research content of this paper is mainly divided into the following four aspects:Firstly,the preparation of MoS₂ nanosheet.The modified mechanical exfoliation method was used to prepare MoS₂ nanosheet with different layers on different substrates.The thickness of MoS₂ was measured by atomic force microscope,and the number of MoS₂ layers was confirmed by Raman spectroscopy.Secondly,scanning kelvin probe microscopy?SKPM?was used to study the electrical properties of MoS₂.Discuss the factors affecting SKPM test,and study the electrical properties of MoS₂ in MoS₂/Si O2,MoS₂/Pt and MoS₂/Ba Ti O3 heterojunction.The results show that the work function of MoS₂ decreases with the increase of the number of layers,and the work function of MoS₂ tends to a constant value due to the shielding effect when the thickness is close to the bulk.Thirdly,conducting atomic force microscopy?CAFM?was used to study the electrical transport performance of MoS₂.First,the conductivity of MoS₂ on MoS₂/Pt heterojunction was studied.It was found that with the increase of layer number,threshold voltage and barrier height increased,electron affinity decreased,and work function decreased.Secondly,the effect of voltage on the electrical transmission performance of MoS₂/Pt heterojunction is studied.These results show that the work function decreases with the increase of MoS₂ layer number,which is consistent with the results of scanning kelvin probe microscope.Fourthly,bimodal atomic force microscopy?AMFM?was used to study the mechanical properties of MoS₂.A new method for quantitative measurement of Young's modulus of two-dimensional layered materials by atomic force microscopy is proposed.The influence of heterojunction bonding force on Young's modulus of MoS₂ is discussed.Studies shown that the Young's modulus of MoS₂ has a great relationship with the heterojunction.The Young's modulus of monolayer MoS₂ in MoS₂/Si O2 is 83 ± 5 GPa,the Young's modulus of monolayer MoS₂ in MoS₂/Pt heterojunction is 263 ± 50 GPa,and the Young's modulus of monolayer MoS₂ in MoS₂/Ba Ti O3 heterojunction is 179 ± 5 GPa.The MoS₂/Si O2 and MoS₂/Ba Ti O3 heterojunctions have strong binding force,which has a great influence on the Young's modulus of MoS₂.The MoS₂/Pt heterojunction has weak binding force and has little effect on the Young's modulus of MoS₂.