The effects of x-ray irradiation on a-IGZO TFTs used for active pixel sensor

In this paper, the behavior of the amorphous indium–gallium–zinc-oxide (a-IGZO) thin film transistors (TFTs) after X-ray irradiation is analyzed. With the increase of irradiation dose, the a-IGZO TFTs show more negative shifts of threshold voltage (Vth), while both the field effect mobility and subthreshold swing (S.S.) keep fairly constant. Not like being a switch in passive pixel sensor (PPS), the Vth shift of the TFT in active pixel sensor (APS) can result in variation in the output signal. With techniques of compensating Vth shift, a-IGZO TFTs are more suitable for the application of Xray image sensors from the viewpoint of stability.