High-Performance Solution-Processed ZrInZnO Thin-Film Transistors

We report on the high performance and high stability of thin-film transistors (TFTs) using solution-processed Zr-In-Zn-O (ZIZO) as an active layer. The effects of adding Zr to In-Zn-O, particularly the electrical characteristics of their thin films and TFTs, were systematically investigated. The Zr effectively controlled the oxygen vacancies because of its low standard electrode potential, which was confirmed by modifications in the optical bandgap energy, carrier concentration, and oxygen-vacancy density of the ZIZO thin films. Consequently, we found that the “off” current decreased and the threshold voltage increased with the increasing Zr content. The optimal ZIZO TFT was obtained at a Zr/In/Zn mole ratio of 0.05 : 2 : 1, and its “on/off” ratio, channel mobility, and subthreshold swing voltage were ~ 10
⁹
, 6.23 cm
²
·V
^-1
·s
^-1
, and 0.19 V/dec, respectively, which are comparable to those of vacuum-processed oxide TFTs. Furthermore, the performance and bias-stress stability of the ZIZO TFTs were improved as a result of the reduced interface charge trapping.