Improved Electrical Performance and Bias Stability of Solution-Processed Active Bilayer Structure of Indium Zinc Oxide based TFT

We fabricated active single- and bilayer structure thin film transistors (TFTs) with aluminum or gallium doped (IZO:Al or IZO:Ga) and undoped indium zinc oxide (IZO) thin film layers using an aqueous solution process. The electrical performance and bias stability of these active single- and bilayer structure TFTs were investigated and compared to reveal the effects of Al/Gal doping and bilayer structure. The single-layer structure IZO TFT shows a high mobility of 19 cm(2)/V.s with a poor positive bias stability (PBS) of Delta V-T + 3.4 V. However, Al/Ga doped in IZO TFT reduced mobility to 8.59.9 cm(2)/V.s but improved PBS to Delta V-T + 1.61.7 V due to the reduction of oxygen vacancy. Thus, it is found the bilayer structure TFTs with a combination of bottom- and top-layer compositions modify both the mobility and bias stability of the TFTs to be optimized. The bilayer structure TFT with an IZO:X bottom layer possess high mobility and an IZO bottom layer improves the PBS.