Improvement of Amorphous InGaZnO Thin‐Film Transistor Using High‐k SrTa2O6 As Gate Insulator Deposited by Sputtering Method

In this paper, the InGaZnO‐based thin‐film transistors (TFT) with the sputtered high‐k SrTa2O6 (STA) as a gate insulator are fabricated. The IGZO‐TFT with STA show low voltage operation below 5 V with good TFT performances, i.e., filed effect mobility of 11.1 cm2 V−1 s−1, threshold voltage of 0.6 V, sub‐threshold swing of 163 mV/decade, and on/off ratio of 7.8 × 109. Compared to the thermally grown SiO2 gate insulator, the sub‐threshold swing is improved by use of STA gate insulator. In addition, the high on‐current and low gate leakage current are obtained. These characteristics are attributable to the sufficient electrical properties of STA, i.e., high dielectric constant of 30 and low leakage current density of 2.6 × 10−8 A cm−2 at 300 kV cm−1.