Effects of Illumination on the Noise Behavior of Amorphous Indium Gallium Zinc Oxide Thin Film Transistors

In this paper, we investigate the response of low-frequency noise to the light for the amorphous indium gallium zinc oxide (a-IGZO) thin film transistors (TFTs). Compared with the case of nonillumination, the noise level increases with the light intensity. We find that the induced noise is more related to the drain current (I _D ) with or without illumination, even though the corresponding gate voltage can be different. With fixed light intensity, the noise induced at the same I _D keeps the same regardless of the illumination history. The noise mechanism is analyzed to be mainly the carrier mobility fluctuation, but carrier number fluctuation becomes important under illumination. We speculate that oxygen vacancies generated by light affect the trapping and releasing of carrier. It thus leads to the noise increasing with illumination.