The Fabrication And Investigation Of High-Performance Metal Oxide Thin-Film Transistor Based On Solution Process

Oxide semiconductor thin film transistor?TFT?has the advantages of high mobility,good conductivity and high optical transparency,which can well meet the requirement of large-area display driver circuit.It has great development potential in the field of the next generation of flat panel display and is very promising as the foundation of the next generation of electronic devices.Moreover,oxide semiconductor TFT has the advantages of low cost,large area production,low temperature preparation and good compatibility with flexible substrate,which opens up a new way for portable flexible flat panel display.Among many thin-film growth technologies,solution method is more suitable for low-temperature processing on large-area flexible substrate due to its simple preparation process and low production cost.Therefore,it has great application prospects in the field of large-area low-cost flexible display,wearable flexible electronics.In this paper,different high performance oxide TFTs were prepared by traditional solution method.The main research contents and results are as follows:1.In₂O₃ TFT was prepared by aqueous solution method and solution self-combustion method at annealing temperatures of 180°C,210°C and 250°C.The surface roughness of In₂O₃ thin films prepared by the two methods was measured by atomic force microscopy?AFM?.It was found that the surface roughness of In₂O₃ thin films was at nanometer level,showing smooth and uniform characteristics,which was conducive to the acquisition of high-performance devices.With the increase of annealing temperature,the saturation mobility of the device increased.When the annealing temperature was 250°C,the saturated mobility of In₂O₃ TFT prepared by aqueous solution method was 1.5 cm²V^-1s^-1,the threshold voltage was 6 V,the on/off current ratio was 5.5×10³,and the saturated mobility of In₂O₃TFT prepared by solution self-combustion method was 0.3 cm²V^-1s^-1,the threshold voltage was 1 V,and the on/off current ratio was 2.3×10³.It was found that In₂O₃ TFT prepared by solution self-combustion method at low temperature had more stable performance,while In₂O₃ TFT prepared by aqueous solution method at high temperature had better performance.2.Heterojunction TFT based on In₂O₃ and IZO were fabricated by aqueous solution method at annealing temperature of 300°C.Firstly,In₂O₃ TFT and IZO TFT of single channel layer were prepared to form control group.It was found that heterojunction structure could effectively improve the electrical performance of devices.Among several kinds of heterojunction TFTs,In₂O₃/IZO heterojunction TFT had the best electrical performance.Its saturation mobility was 31 cm²V^-1s^-1,the threshold voltage was 12 V,and the on/off current ratio was 1.48×10⁶.By analyzing the surface morphology and high resolution XPS spectra of the thin film,it was found that the surface roughness and interface defects of In₂O₃/IZO heterojunction thin film were the least,which further proved the conclusion that In₂O₃/IZO heterojunction TFT had the best performance.In₂O₃/IZO heterojunction TFT was fabricated under the annealing temperature of 250°C and 300°C.The effect of annealing temperatures on device performance were investigated.It was found that increasing annealing temperature could effectively reduce the defects in the films and improve the performance of In₂O₃/IZO heterojunction TFT.3.ZnO TFT was prepared by aqueous solution method under low temperature?300°C?,and the properties and electrical properties of the ZnO thin film were analyzed.The electrical properties of ZnO thin film surface treated by PCBA were improved significantly,because the interface modification layer effectively reduced the interface state defects and contact resistance of the device.Moreover,the interfacial modification layer could effectively passivate the surface of ZnO thin films and improve the shelf-life stability and bias stress stability of devices.ZnO TFT with high work-function Ag as source/drain electrodes was obtained under the same preparation conditions.It was found that the interface modification layer could effectively reduce the contact resistance and enhance electron injection,optimize the interface contact between source/drain electrodes and ZnO channel layer,and then improve the performance of TFT devices.