Preparation And Study Of Thin Film Transistors Based On Aqueous Ultra-thin ZrO 2 High ? Dielectric Layers

Since the emergence of flat-panel display technology in 20 th century,mankind has entered the information society.Therefore,a qualitative leap happened in the human society.The core element of the flat display is thin film transistor?TFT?.With the rapid development of science and technology,flat-panel display device has higher requirement on the performance of the TFT.Amorphous silicon TFT and polysilicon TFT play important roles in active matrix liquid crystal displays?AMLCD?and active matrix organic light emitting diode?AMOLED?.However,the traditional amorphous silicon TFT and polysilicon TFT exhibit several defects,such as low mobility,strong photosensitivity,complex preparation process and higher cost,which restrict their application in a wide field.Metal oxide TFTs have several merits that make them candidates in flat-panel displays,such as simple preparation technology,high stability,good transparency,high mobility and large scale production.It shows great application prospects.In this thesis,the as-prepared water-induced amorphous high-k zirconium oxide?ZrO₂?thin films were fabricated by a sequential process,including a UV-assisted photochemical treatment and thermal annealing process at temperatures lower than 300 oC.It is observed that the leakage current density of ZrO₂ thin film decreases,and the capacitance increases with increasing annealing temperature.To verify the application possibilities of ZrO₂ thin films as the gate dielectric in complementary metal-oxide semiconductor?CMOS?electronics,both n-type In₂O₃ and p-type NiO_x channel layers were integrated on ZrO₂ dielectrics and their corresponding electrical performances were examined.The In₂O₃/Zr O₂ TFT annealed at 250 oC exhibited a high electron mobility of 10.78 cm2/V s,a small subthreshold swing of 75 mV/dec,and large on-off current ratio?Ion/Ioff?of around 106.Moreover,the p-type NiO_x/ZrO₂ TFT exhibited an Ion/Ioff of 105 and a hole mobility of 4.8 cm2/V s.It is noted that both n-and p-channel oxide TFTs on ZrO₂ could be operated at voltages lower than 4 V.The low-temperature fabrication process represents a great step towards the further development of low-cost,all-oxide CMOS electronics on flexible substrate.