The Preparation And Performance Improvement Of New ZnO-based Thin Film Transistor

Thin film transistors(TFTs), as the core components of liquid crystal display, play an important part in improving display quality and enlarging display domain of plat panel display devices. Traditional TFTs use hydrogenated amorphous silicon as active layer, which is not compatible with the need of modern display field. Hydrogenated amorphous silicon TFTs has low mobility (～1cm2/Vs) and high price, in addition, sensitive to visible light. These drawbacks make it is urgent to develop new TFTs adapted to modern life.In this research, firstly, the study progress and status of the thin film transistor (TFT) were included, the structure and working principle of TFT also were explained in detail. Furthermore, there are also some problems to be solved. In the production stage of a simple thin-film transistor (TFT),this paper make a deep study from the optimum thickness of the active layer and the insulating layer, and the optimal annealing time three aspects, ultimately determined the optimal thickness of the active layer ZnO and the insulating layer Ta2O5were50nm and250nm, respectively, the optimal annealing time is15min. What is more, we got a better device performance:the threshold voltage of8.8V, subthreshold swing of4.38V/decade, the current on-off ratio is2.4×10.Further, we used HfO2as the insulation layer and then got better performance than the former, we got a better device performance:the threshold voltage of3V, subthreshold swing of1.78V/decade, the current on-off ratio is1.7×104. Meanwhile, we had done a comparative study of two kind different electrode materials (Au and Al), the results showed that:device performance of aluminum electrodes is better than the gold electrode.Finally, the TFT of a sandwich structure with Al2O3-Ta2O5-Al2O3as the insulating layer also was produced, expecting a better performance than the former thin film transistor. The threshold voltage of the device is3V, the current ratio is greater than1.7×101, the device performance did not improve, the reasons may be the Al2O3layer of the middle is too thin, resulting in the leakage current increases.