Research On The Preparation And Modification Of Indium-based Metal Oxide Thin Film Transistor

As the core component of flat panel display,thin film transistor（TFT）has broad application prospects in lighting,communication,sensor and other fields.The further development of traditional silicon-based TFT in the flat panel display industry is limited by the problems of low mobility,complex process,and poor stability.Compared with silicon-based TFT,metal oxide TFT has attracted much attention from researchers due to its excellent electrical properties,high transmittance in the visible light range,and lower preparation temperature.Indium oxide（In₂O₃）,as a representative material in oxide semiconductors,is widely used as the active layer of high performance TFT.However,the In₂O₃ TFT prepared by solution method at low temperature shows low carrier mobility and poor stability due to its excessive defect states in the In₂O₃thin film.In this paper,high performance indium-based TFT was prepared at low temperature by means of structural design（In₂O₃:F/In₂O₃homojunction）and process improvement（oxygen plasma treatment of ZrO₂）,and the neuromorphic application of In₂O₃ TFT was explored.The main work is as follows:1.The TFT based on In₂O₃:F/In₂O₃ homojunction was prepared by fluorine doping of In₂O₃ thin films using sol-gel method.The active layer consisted of a stacked structure of In₂O₃:F films with different doping concentrations of F.The electrical properties of In₂O₃:F/In₂O₃TFT could be precisely controlled by adjusting the height of the barrier between the active layers with the change of the work function of In₂O₃:F films.The TFT based on In₂O₃:F/In₂O₃homojunction showed the best performance when the F doping concentration of the front channel layer was 15%,including the carrier mobility of 5.69 cm²/Vs,the I_on/I_off of 10⁸ and good positive bias stability.In order to further improve carrier mobility of TFT devices,atomic layer deposition（ALD）was used to deposit alumina（Al₂O₃）as a high k-dielectric layer.The integrated Al₂O₃/In FO-15/In₂O₃ TFT devices achieved further performance enhancement.The switching ratio(I_on/I_off)was about 10⁸,and the threshold voltage(V_TH)was 1.4 V.And the field effect mobility(μ_FE)was 31.49 cm²/Vs,which was 6 times higher than that of In₂O₃:F/In₂O₃ TFT based on SiO₂ dielectric layer.This research can provide a new experimental basis for the preparation of high performance indium-based TFT at low temperature.2.The In₂O₃ TFT based on oxygen plasma treatment of ZrO₂ was prepared by sol-gel method.The defect states in the ZrO₂ films were reduced by the introduction of low cost and simple oxygen plasma treatment technology.It was found that the carrier mobility of In₂O₃TFT based on oxygen plasma treatment increased with the increase of oxygen plasma treatment power,indicating that the passivation effect of oxygen plasma treatment on ZrO₂thin films reduced the leakage current and the D_it of In₂O₃ TFT.It was found that the In₂O₃TFT integrated with ZrO₂ dielectric films treated by oxygen plasma of 80 W showed the best performance and could be applied to the design of high performance and low-power consumption flat panel displays.Theμ_FE was 3.34 cm²/Vs,and the V_TH was 0.63 V.Finally,the application of In₂O₃ TFT in the simulation of neuromorphic devices was explored.The polyvinyl alcohol（PVA）solution containing free protons was used as the ionic solution,and the In₂O₃ film was used as the channel layer.The simulation of various synaptic plasticity was successfully achieved,which provided a new idea for the development of low power neural devices.