Study On The Effects Of Argon Plasma Treatment On The Electrical Properties Of Two-Dimensional Semiconductors

In recent years,two-dimensional（2D）semiconductor nanomaterials,represented by graphene,have become a research hotspot in the field of new generation semiconductor nanomaterials with great potential for applications in microelectronics because of their excellent electrical,mechanical,thermal and optical properties.However,the variety of materials is,after all,limited,and it is necessary to introduce controlled doping in order to diversify and functionalize the properties of 2D materials.Here,we have explored the modification of 2D semiconductor materials by argon（Ar）plasma and its principles.The main work and conclusions of this thesis are as follows:（1）Controlled n-and p-type doping of tungsten diselenide（WSe₂）and molybdenum ditelluride（Mo Te₂）were achieved by controlling the Ar plasma treatment conditions.A short treatment time leads to an increase in the electron current in WSe₂and Mo Te₂,resulting in n-type doping.As the plasma treatment time increases,the electrical properties exhibited anomalous p-type doping with increased hole currents.The Raman and the XPS spectra showed the presence of oxygen-binding bonds（O-W,Mo,Se and Te）in WSe₂ and Mo Te₂.These results indicate that the Ar plasma treatment resulted in considerable vacancies and edge defects in the top layer of the material,which are immediately occupied by oxygen atoms or oxidized to introduce oxygen doping when it is exposed to air.Meanwhile,the increase in thickness further after treatment demonstrates the formation of uniform oxide films in the top layer of WSe₂and Mo Te₂.（2）Ar plasma modulates the electrical properties of other two-dimensional semiconductors（rhenium disulfide（ReS₂）and tellurium（Te））.With the increase of treatment time,the thickness of ReS₂ was thinned,and its current and electron mobility decreased and then increased without changing the properties of ReS₂ semiconductor.In addition,the sensitivity of treated ReS₂ to light was effectively improved.The electrical property curves of single-element two-dimensional Te under different pressure groups as a function of Ar plasma treatment time.The results showed that a pressure of 50 Pa was the most suitable for Te,and the treatment for 6 s introduces oxygen defects to form p-type doping leading to an increase in current,and the conductive channel of Te field-effect transistors（FETs）changes from the original strong n-type to the hole-dominated p-type semiconductor characteristic,and the on/off ratio is increased by 3 orders of magnitude,which effectively improves the current regulation of the gate.（3）Application study of two-dimensional semiconductors after Ar plasma treatment.On the one hand,a combination of CMOS inverters using doped n-type and p-type WSe₂ FETs devices was developed.The experimental results were accordance with the theoretical results of the inverter and showed fast and stable switching characteristics.On the other hand,the storage performance of the WSe₂/Mo Te₂heterojunction is investigated on the basis of Ar plasma introduction doping:a huge hysteresis window of 50 V is presented at a gate voltage±60 V sweep and the stability of data storage is enhanced to some extent.