Low-Operating-Voltage Solution-Processed InZnO Thin-Film Transistors Using High-kSrTa₂O₆

Abstract

In this research, an InZnO channel layer and a high-k SrTa2O6 gate insulator were both fabricated using a solution process for the application of thin film transistors (TFTs). A low turn-on voltage of -1.2 V, a low threshold voltage of 0.8 V, a high on/off current ratio of 5×106 at a low voltage of 5 V, and a saturation mobility of 0.24 cm2/(V·s) were obtained. The diffusion of oxygen from the high-k SrTa2O6 gate insulator to the InZnO channel layer through the interface was effective for decreasing the concentration of impurities in solution-processed InZnO TFTs and subsequently enhancing mobility. Furthermore, a very low subthreshold swing value of 0.1 V/decade was obtained. This low value was due to the very smooth surface and the voltage-independent high dielectric constant of 36 for the SrTa2O6 thin film.