Investigation of photo-induced hysteresis and off-current in amorphous In-Ga-Zn oxide thin-film transistors under UV light irradiation

We investigated the hysteresis and off-current (I_off) of amorphous In-Ga-Zn oxide thin-film transistors illuminated by 400 nm light at various intensities. Both hysteresis and I_off are induced by the ionized oxygen vacancy (Vo²⁺) that forms at the interface between the gate insulator and active layer. In our measurements, I_off was much less than the estimated photocurrent. I_off showed a rapid nonlinear increase with light intensity, while the photocurrent of a conventional crystalline semiconductor is expected to show a linear relationship. Furthermore, a numerical analysis suggested that the response time of Vo ²⁺ should be considered when analyzing the hysteresis of these devices.