Preparation And Properties Of Metal Oxide Films And Transistors

Oxide thin film transistors play important roles in next generation active matrix liquid crystal displays(AMLCD) and active matrix organic light emitting diode(AMOLED). As the development of the science and the improvement of the technology, the requirements of the flat panel display devices to every aspect of the TFTs become higher. TFTs with different semiconductors have different performances, thus TFTs made of different materials are studied, including amorphous silicon TFTs, polycrystalline silicon TFTs, microcrystalline silicon TFTs, organic TFTs and oxide TFTs. Traditional amorphous silicon TFT can be fabricated at low temperature but exhibits low field effect mobility and high optical sensitivity. The field effect mobility of polycrystalline silicon TFTs have been improved, however, due to the complex fabrication craft and the high cost, it cannot be massively used. Organic materials can decrease the cost of the TFT, but it’s hard to increase its carrier mobility. Oxide TFTs can be fabricated at room temperature, be manufactured in large scale. Oxide TFTs also have high field effect mobility, good stability, high transmittance. Thus oxide TFTs become a hot research topic all around the world.In this paper, In2O3 TFTs based on SiO2 dielectric were fabricated. The channel thickness dependence of In2O3 TFTs was investigated. In view of the limitation of the traditional dielectric SiO2, high-k aluminum oxide dielectrics were fabricated by sol-gel method. The effects of thickness and annealing temperature on the properties of the thin films were studied. The results demonstrate that spin-coating three times and 550 oC annealing were appropriate. A bottom gate top contact TFT was fabricated. The semiconductor layer of ITZO was fabricated by magnetron sputtering. The performance of the TFT was proved to be excellent with an operating voltage of 5 V, field effect mobility of 23.7 cm2/Vs, threshold voltage of 1.5 V, subthreshold swing of 0.22 V/decade, on/off current ratio of 106. The results demonstrate the feasibility of sol-gel method in TFT, and laid a solid foundation of application in transparent electronics and flexible devices.