Maximum applied voltage detector using amorphous In–Ga–Zn–O thin-film transistor exposed to ozone annealing

Abstract

We have developed a maximum applied voltage detector using an α-IGZO TFT exposed to ozone annealing. This TFT has an interesting property; the Ids–Vgs characteristic shifts positively and becomes steep when gate voltage is applied, whereas it recovers the initial one with a small threshold voltage and a large subthreshold swing upon light illumination. Therefore, this TFT can be used as a maximum applied voltage detector; first, light is irradiated to initialize the Ids–Vgs characteristic, next, changing external voltage is applied to the gate electrode, and finally, the maximum applied voltage is obtained from the final Ids–Vgs characteristic.