Study On Performance Improvement Of Metal Oxide Thin Film Transistors Fabricated By Aqueous Solution Process

Oxide thin film transistors?TFTs?have a wide range of applications because of their advantages such as high electron mobility,high transparency,and good uniformity.Compared with traditional preparation methods such as vacuum deposition,the solution method has attracted great attention in the research of oxide TFTs due to its simple process,low cost,and no need for high temperature and high pressure.Nowadays,although the mobility of the solution-processed oxide TFT is comparable to that of the vacuum-processed oxide TFT,problems such as poor stability have become a key technical bottleneck restricting its application.In order to overcome these difficulties,Sr doping is proposed for suppressing oxygen vacancies,which greatly improves the stability of the aqueous In₂O₃-TFT device.However,the mobility of the device decreases at the same time.In order to solve the problem that the mobility and stability of TFT devices are mutually restricted,a novel anion-cation?Sr-N?co-doping system is constructed in this paper.Through the dual effect of Sr-N co-doping on the active layer of TFT,the mobility and stability of aqueous In₂O₃-TFT devices are simultaneously improced.In addition,in this paper,Gd₂O₃ was prepared as the dielectric of the oxide synapse transistor by aqueous route.The fully aqueous solution-processed In₂O₃/Gd₂O₃-TFT was prepared and successfully simulated the short-term plasticity of synapses.The main research contents and innovations of this article are as follows:?1?SrInO films and SrInO-TFT are prepared by the aqueous route.The effect of Sr doping on the electrical properties and stability of In₂O₃-TFTs were investigated.When the doping concentration of Sr is increased,although the electrical performance of SrInO-TFT would be deteriorated?the mobility decreases from 11.85 cm²/Vs to5.41cm²/Vs,the threshold voltage increases from 4.43 V to 7.71 V?,the bias,lllumination,and thermal stability of device are greatly enhanced.SrInO-TFT with Sr doping mol ratio of 2 mol%has shown the best stability.Under PBS and NBIS,the?35?V_TH value?Sr:2 mol%?of the device is 1.7 and-2.02 V,which are much smaller than the?35?V_TH value?3.37 and-5.07 V?of pure In₂O₃-TFT.It is found that the reason for this phenomenon is that the incorporation of Sr suppress the generation of oxygen-related defects in oxide film by forming stronger bonds with oxygen.?2?InSrNO films and InSrNO-TFT are prepared by the aqueous route.The effects of co-doping Sr and N on the electrical performance and stability of the device are studied.It is found that the N doping can simultaneously improve the stability and mobility of device.By controlling the content of Sr and N,the electrical stability under PBS/NBIS/TS are significantly improved.The optimized InSrNO-TFT?Sr:0.5mol%,N:5 mol%?shows relatively best electrical performance(?=16.38 cm²/Vs,V_TH=2.91 V,and SS=0.24 V/decade.The?35?V_TH of device after 3600 s PBS is 1.54 V,and-1.02 V after 3600 s NBIS.The results show that the Sr-N doping can effectively suppress the oxygen vacancy,reduce the defect density of state,and provide free electrons,which can improve the stability and mobility of the device at the same time.?3?Gd₂O₃ film prepared by aqueous route is used as the dielectric of the oxide synapse transistor.Gd₂O₃ films exhibit large unit capacitance?320 n F/cm² at 20 Hz?and typical characteristics of non-linear dielectrics.The fully aqueous solution-processed In₂O₃/Gd₂O₃-TFT exhibits an acceptable electrical performance with a V_TH of 1.24 V and a SS of 0.17 V/decade.In this chapter,aqueous solution-processed In₂O₃/Gd₂O₃-TFT successfully simulates the short-term plasticity and other synaptic behaviors.By adjusting the properties of pulses applied to the gate,the short-term memory of device response to presynaptic pulse stimulis is enhanced.In₂O₃/Gd₂O₃-TFT also shows application potential in high-frequency filtering and other applications.Moreover,the effects of light stress on the synaptic behavior of In₂O₃/Gd₂O₃-TFT are investigated.The results confirm that photon energy greater than the activation energy?E_a?required for oxygen vacancy ionization in Gd₂O₃ can enhance short-term memory of device.