Research About Fabrication And Electronic Properties Of Back-gate Mos₂ Field-effect Transistor

MoS₂ membrane is an excellent two-dimensional nanomaterial with 1.3¹.8 eV adjustable bandgap.The MoS₂ field effect transistor?FET?owns reasonable electron mobility and superior on/off ratio?>10⁷?which is able to be the alternative materials of silicon-based semiconductor.Now,the two-dimensional field effect transistors are commonly fabricated by electron beam lithography,inducing the existence of residual at the interface of electrode and channel.In this work,the fabrication process and corresponding properties of MoS₂ field effect transistor by transferring electrodes with metal probe were elaborated detailedly.The modification mechanism of electronic properties of MoS₂ devices,which were treated by low temperature oxygen plasma,has been investigated.MoS₂ samples were prepared by mechanical exfoliation and chemical vapor deposition,respectively.The prefabricated patterning Au electrodes were transferred onto MoS₂ channel by metal probe with the assistance of high-resloution optical microscope,forming the field effect transistor.Raman spectra were uitilized to characterize the layer and quality of sample by observing E¹_2gand A_1gg characteristic peak and AFM was used to characterize the thickness and topography of sample.The electronic properties of MoS₂ field effect transistors based on above method were tested by semi-automatic probe station.The electronic measure indicates that the contact effect of transistor was benign and output characteristic curves were linear.Meanwhile,output characteristic can be modulated by gate voltage effectively.The transfer characteristic curves demonstrated that MoS₂ field effect transistor is N-type.The electronic property of monolayer MoS₂ transistor prepared by mechanical exfoliation is preferable.MoS₂ transistors can be fabricated by transferring electrodes with metal probe effectively.The contact properties of transistors were poor before anneal and output characteristic curves were nonlinear,indicating the existence of nonnegligible tunneling barrier.The electrical properties of transistors can be improved by 200?annealing at N₂ atmosphere after 30 minutes.The adsorption morphology between patterning electrodes and MoS₂ has been changed owing to the process of annealing,resulting in the enhancement of vdWs gap at the contact interface.Low temperature oxygen plasma was performed to modify MoS₂ transistors and the elecronical properties of transistors can be improved obviously after the treatment of low-power oxygen plasma.The vacancy of sulphur in MoS₂ can be modified by oxygen plasma effectively and short range scattering can be improved.However,the electronic properties of transistors declined after the treatment of high-power oxygen plasma.The high-energy oxygen particle collided with MoS₂ which results in the increase of defect.Raman spectra and X-ray spectra indicates that the structure of MoS₂ has been damaged and Molybdenum trioxide has been introduced.The SKPM module and SMM were employed to analyze the signal of surface potential difference and capacitance of samples after the treatment of oxygen plasma.The signals of surface potential difference and capacitance of chemical vapor deposition samples were heterogeneous.Combining with the features of mass adsorabtes at the boundary of triangular monocrystal,it can be interpreted that oxygen plasma will interact with the boundary of triangular monocrystal of MoS₂.