Performance Improvement And Application Of Indium Zinc-based Metal Oxide Field Effect Transistor

With the development of consumer electronics,the field effect transistor（FET）has become the switch and driving device of flat panel display.Traditional silicon-based FETs are faced with the disadvantages of low mobility,poor transparency and uniformity in visible light region,which limit their development in display industry.At present,metal oxide has become the main research object in the field of flat panel display due to its excellent charge transport characteristics,excellent electrical stability and high transparency in the visible region.Indium zinc oxide（IZO）has been widely used as the active layer of high-performance FETs among many metal oxide materials.Owing to the IZO channel layer contains many defects and oxygen vacancies,there will be some inherent defects in device operation.In the preparation of FET,electrospinning and sol-gel methods have attracted increasing attention because of their advantages such as low cost,simple preparation process and large-scale production.The performance improvement and application of indium zinc base oxide field effect transistor are studied,which can be divided into three parts.1.The IZO/HIZO double-layer thin film transistor（TFT）was prepared by spin coating method,in which indium hafnium zinc oxide（HIZO）layer was used as the passivation layer and back channel to isolate the external oxygen in IZO/HIZO TFT.It is confirmed that the hafnium（Hf）in the HIZO layer regulates the oxygen vacancy in the front and back channels by adsorbing oxygen ions in the IZO layer during the subsequent annealing process,which improves the field-effect mobility and positive bias stability of the device.The results show that the overall performance of IZO/HIZO TFT is best when the Hf doping concentration of HIZO layer is 15%Hf,including on/off current ratio of 2.3×10⁸,mobility of 7.08 cm²/V s and excellent positive bias stability.In addition,Zr O₂/IZO/HIZO/ITO TFT was successfully fabricated on indium tin oxide（ITO）glass substrate with zirconium dioxide（Zr O₂）dielectric,and a field-effect mobility of 20.64 cm²/V s.This work provides an effective way for low cost and high performance transparent TFT.2.HIZO nanofibers with different Hf doping concentrations were prepared by electrospinning and integrated into the FET.As the doping concentration of carrier inhibitor Hf increases,the carrier concentration of HIZO nanofibers FETs decreases and the switching ratio of the device increases.The results show that the concentration of oxygen vacancy in HIZO nanofibers can be reduced by Hf incorporation.In order to further reduce the operating voltage for low-power devices,the Al₂O₃ dielectric film prepared by atomic layer deposition is used as the insulation layer of HIZO nanofibers FETs.The threshold voltage is 0.24 V,the switching ratio is 10⁷,and the carrier mobility reaches 8.23cm²/V s.3.To explore the application of HIZO nanofibers prepared by electrospinning in the simulation of neuromorphic devices.Using H⁺/PVA electrolyte as gate medium and HIZO nanofibers as semiconductor layer,the electric-double-layer ion gate transistor was fabricated.The simulation of various synaptic plasticity under different intensity of pre-pulse stimulation provides a new idea for the subsequent development of neuromorphic devices.