Characterizations on the Device Stabilities of the Oxide Thin Film Transistors Using In-Ga-Zn-O Channels Prepared by Atomic-Layer Deposition

We investigated the device stabilities of thin-film transistors using In-Ga-Zn-O (IGZO) channels prepared by atomic-layer deposition process when the channel thickness was varied to 10 and 6 nm. Even when the IGZO channel thickness was reduced to 6 nm, the device exhibited good performances with a high saturation mobility of 15.1 cm²/Vs and low subthreshold swing of 0.12 V/dec. The positive and negative bias stress stabilities were found to be excellent. Under positive bias temperature stress stability test at 60 °C for 10⁴ s, the threshold voltage shifts of the device were estimated to be as low as -2.2 and -1.8 V for the channel thicknesses with 10 and 6 nm, respectively. The time dependences of threshold voltage shift under various bias, temperature, and illumination stress conditions could be explained by a stretched-exponential equation.