Fabrications And Studies Of Performance Oxide Thin-film Transistors And Inverters

With the TFTs expansion of application, people also want to have a good qulity flat-panel display with high resolution and large area based on the TFTs, which promotes the development of TFTs with a higher mobility ratio, smaller threshold voltage and larger optical transmittance. With the developing of the research, the oxide semiconductor TFTs get much attention and recognition of the researchers as the excellent performance and the simple preparation process. At present, some oxide TFTs in good performance get preliminary application in practice. For the oxide TFTs have many fabrication technology, we main used the magnetron sputtering to prepare n-type IZO-TFTs on the silicon substrates and the glass substrates. We prepared the transparent IZO-TFT with the zirconia（ZrO₂） film used as the insulating layer on the glass substrates. Based on this IZO-TFT devices, we prepared the high voltage gain of the resistor loaded inverters. We also prepared the p-type CuO-TFT by magnetron sputtering for preparation of the complementary inverters.First, this paper described the historical development of the TFTs, the silicon TFTs have a long history and have much mature preparation technology than the oxide TFTs. At present, the silicon TFTs have been applied widely, and the oxide TFTs have been applied gradually with the deepening of research. Then we described the advantages and disadvantages of the different classification and different structures of the transistors. The different TFT structures have different influence on TFTs performance. But different structure TFTs working principle are the same, we prepared the TFTs with a bottom gate electrode structure. In order to improve the TFTs performance, we prepared the high dielectric coefficient（high-k） of ZrO₂ film as the gate electrode insulating layer by sol-gel method. The high-k material as the insulating layer has a great influence on reducing the TFTs saturation voltage and the leakage current, and films were prepared by sol-gel with body solution after annealing in the air. As the films show amorphous states, little film grain boundary could reduce leakage current. We prepared completely transparent IZO–TFTs with the ZrO₂ film and ITO glass substrates. The devices have good optical transmittance and small saturation voltage, which could be applied in transparent low power circuits. We found the off-state current increased more obviously in high intensity ultraviolet radiation. We also used the transparent TFTs prepared a low input voltage resistor loaded inverter. At the same time, in order to fabricate the complementary circuits, we also prepared the IZO-TFTs and Cu O-TFTs on silicon substrates. The IZO-TFTs had a good saturation characteristic under 30 V and a high on-off ratio preppared at room temperature. But the CuO-TFT performance was not ideal prepared at room temperature, the performance of the CuO-TFTs had been improved after annealing at 500℃ in air, but not enough to apply in the complementary inverter circuit. We need to be further experimental studies.