Amorphous Indium Gallium Zinc Oxide thin film transistors with interface modification layer

Large threshold voltage has been an issue of the amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) based thin film transistors (TFTs), leading to the electrical output characteristic called "Hard saturation". Therefore, a high positive voltage is required to induce the channel layer for achieving the on-state operation of TFT. In this work, the a-IGZO TFTs with dual stacks of gate dielectric layers consisted of SiOx and a buffer layer of Al₂O₃, HfO_x, and HMDS film are developed to improve the interface between a-IGZO layer and gate SiO_x insulator layer. The improvement can effectively suppress the hard saturation behaviors. Furthermore, with the buffer layer, the hysteresis effects of the TFTs are reduced obviously, compared to the counterpart of without the buffer layer. The experimental results clearly indicate the proposed stacked a-IGZO TFTs have great potential for the application for the advanced AMLCD technology.