Charge pumping method for photosensor application by using amorphous indium-zinc oxide thin film transistors

The study investigated the photoreaction behavior of amorphous indium-zinc oxide thin film transistor (a-IZO TFT), which was thought to be insensitive to visible light. The obvious threshold voltage shift was observed after light illumination, and it exhibited slow recovery while returning to initial status. The photoreaction mechanism is well explained by the dynamic equilibrium of charge exchange reaction between O2 (g) and O2- in a-IZO layer. A charge pumping technique is used to confirm the mechanism and accelerate recoverability. Using knowledge of photoreaction behavior, an operation scheme of photosensing elements consist of a-IZO TFT is also demonstrated in this work.