The authors investigated the photoresponse of a double-layer oxide semiconductor
(GaInZnO–InZnO) thin-film transistor (TFT) under illumination, where the photocurrent in the
negative gate bias region increased significantly without a negative shift in the threshold
voltage. In particular, in the forward gate bias sweep direction (from− VG to+ VG), the
hysteresis of the transfer curves of the photosensor TFT became pronounced when the
negative gate bias and its duration were increased. Additionally, the photocurrent level of …