Screen-Printed Silver Source-Drain Electrodes for a Solution-Processed Zinc-Tin-Oxide Thin-Film Transistor

As a first step to achieve all-printing-processed oxide thin film transistors (TFTs), we prepared solution-processed zinc-tin oxide (ZTO) TFTs by screen printing electrodes for the first time. The source and drain were silver nanoparticles, and the channel length was patterned by using screen printing technology. Different silver nanoinks and process parameters were tested to find optimal source and drain contacts. A finely patterned channel layer of 100 μm in channel length was defined with a 4 μm thickness. The electrical characteristics of solution-processed ZTO with screen-printed source-drain electrodes were comparable to those of solution-processed ZTO with vacuum-deposited electrodes. Relatively good electrical properties of screen-printed solution-processed oxide TFT were obtained: a mobility of 2.3 cm²/V s, an on-off current ratio of 10⁶, a Vth of 17 V and a subthreshold swing of 3.2 V/dec. The bias stability was also characterized.  Because of the microstructure of the device, water and oxygen adsorption from the atmosphere affected the Vth shift and the subthreshold slope change under a gate bias stress.