Fabrication Of Solution-Driven High Performance Indium-Based Thin Film Transistors And Its Application

As the crucial switching components of flat panel display devices,the importance of thin film transistor?TFT?is self-evident.At present,TFT based on metal oxide semiconductors have received extensively attention from commercial and research fields due to their higher optical transmittance,higher mobility and excellent stability.At the same time,replacing SiO₂with hafnium-based oxide materials having a high dielectric constant can not only reduce the leakage current density of gate dielectric layer,but also decrease the driving voltage and power consumption of TFT devices.In this thesis,by using low-cost solution-driven method,indium-based oxide thin films and hafnium-based gate dielectric layer were prepared,low-voltage-driven high performance indium-based TFT devices were also successfully constructed;the inverter were constructed based on TFT devices,and its gain characteristics and response behaviors were investigated.The detailed contents and results of this paper are listed as following:1.The novel HfGdO_x gate dielectric thin films were prepared by eco-friendly aqueous solution method,and the influences of annealing temperature on the physical properties and chemical components of HfGdO_x thin films were investigated.Based on HfGdO_x thin films,the low-voltage-driven In₂O₃/HfGdO_x TFT device was constructed by using aqueous solution method,which exhibits a mobility of 11.2 cm² V^-1 s^-1 and an ON/OFF-state current ratio of4.1×10⁶.Based on the In₂O₃/HfGdO_x TFT,the inverter for logic circuits was constructed,which exhibits high gain and good full swing characteristics.Experimental results manifest that solution-driven HfGdO_x thin films have attractive application prospects in the fields of low-voltage-driven TFT and inverters.2.InZnO thin films were prepared via environmental friendly aqueous solution method,and the influences of elemental molar ratio?In:Zn?on the optical properties,micro-structure and chemical components of InZnO thin films were systematically investigated.Based on the analysis of electrical performances of InZnO/SiO₂ TFT devices,the optimal elemental molar ratio of InZnO thin films was obtained.Based on the optimal elemental molar ratio,the low-voltage-driven InZnO/HfO_x TFT device with a mobility of 9.1 cm² V^-1 s^-1 and an ON/OFF-state current ratio of 1.5×10⁷ was constructed.On the basis of the InZnO/HfO_x TFT,the inverter with a high gain of 8.8 was constructed.Those superior electrical parameters exhibit that solution-driven InZnO thin films have the potential application in the fields of low-cost,low-power consumption electron devices.3.Ca doped In₂O₃ thin films were prepared by solution-driven method,and the effects of Ca-doping concentration on the optical properties,surface morphology,micro-structure and chemical components of In₂O₃ thin films were investigated.X-ray photoelectron spectroscopy measurement indicates that Ca-doping can effectively regulate the oxygen vacancies of In₂O₃thin films.Tests of InCaO_x/HfGdO_x TFT devices indicate that 0.5%Ca-doping can effectively modulate the mobility,ON/OFF-state current ratio and bias stability of TFT devices,leading to the optimized performances.The inverter based on the InCaO_x/HfGdO_x TFT shows a gain of 6.0,which is sufficient to drive continuous signal propagation in integrated circuits.All the results indicate that there is a great application prospects for In₂O₃ thin films with appropriate Ca doping in the fields of TFT and inverters.