Preparation And Properties Of In₂O₃-Based Thin Film Transistor By Solution Spinning

Since the IGZO TFT appeared in 2004,the technology of metal oxide thin film transistor(TFT)has been developed rapidly,and a great progress has been made in plane display technology.The TFT,as the core control component of the display,has thus attracted wide attention.With the advantages of ultra-high carrier concentration,good stability and enabling preparation by various methods,metal oxide semiconductors have become the current research hotspot used in TFT.However,the traditional vacuum system preparation method has the disadvantages of high cost and is difficult to prepare in a large-area scale.On the contrary,the sol-gel method has the advantages of simple operation,low price of equipment,high efficiency,large area preparation,good uniformity and can be processed in atmospheric environment,which thus has been extensively studied.Secondly,the insulating layer of the TFT also plays an important role in the performance of the device.With the miniaturization of the size of transistors,there is an urgent need for high-performance dielectric layer materials to meet the requirements of high-performance TFT devices.In order to solve the problems of low cost,miniaturization of size and high performance of thin film transistors,this thesis mainly focuses on how to prepare high dielectric insulating layer ZrO₂ thin films and In₂O₃ thin film transistors by a solution method.Then,high performance thin film transistors were prepared by In₂O₃doping Mg and continuous spin coating.Thus,the following results were obtained:(1)High performance ZrO₂ insulating film were prepared and characterized.The precursor solution was prepared by sol-gel method,and the ZrO₂ thin films was prepared by spincoating technology.In order to promote the densification of the thin films,ultraviolet(UV)activation was used to reduce the annealing temperature,and ZrO₂ gate dense films was obtained by an annealing treatment at 300?.The spin-coated ZrO₂ thin films have ultra-high capacitance per unit area(800 nF/cm² at 20 Hz),smooth surface(root mean square roughness less than 0.5 nm),low leakage current(1 nA/cm²)and high breakdown voltage(5.5 MV/cm).High-quality gate insulation film is the premise and key to obtain transistors with excellent performance.(2)The leakage current of the TFT device were probed and the In₂O₃-Mg TFT was systematically studied.The phenomenon of edge leakage current caused by spin coating technology in the preparation of TFT devices was explored.Then,an experimental scheme that high performance In₂O₃ TFTs can be prepared by Mg doping and UV light annealing technology,was proposed and In₂O₃-Mg TFT devices were successfully fabricated.When the Mg doping ratio is 3%,the device has the best comprehensive performance,with a current switch ratio of 10⁵ and a mobility as high as 15 cm²/Vs.The threshold voltage V_th=1.5 V.The scheme was successfully confirmed.(3)In₂O₃/ZnO heterojunction TFT was fabricated and its preperty was explored.In₂O₃/ZnO heterojunction TFT devices was fabricated by a continuous spin coating technique.The device has a saturation current as high as 1 mA,a current switch ratio as high as 10⁵,a carrier mobility of 8 cm²/Vs and a subthreshold swing of 0.3 V/dec,which are of great significance for the preparation of heterojunction TFT by solution method.