Comparison of Illumination Effect on Amorphous Indium Gallium Zinc Oxide and a-Si Thin Film Transistors

The effect of illumination on the characteristics of an amorphous indium-gallium-zinc-oxide thin film transistor (a-IGZO TFT) fabricated at low temperature was investigated in comparison with the characteristics of an amorphous silicon (a-Si) TFT. The a-IGZO TFT exhibited excellent performance with a mobility of 10.5 cm −2 V −1 s −1 and was free of hysteresis when the gate bias swept both forward and reverse. After illumination with white light emitting diode (LED), the shift of threshold voltage (V th ) and hysteresis was not observed, indicating that the devices have potential application for transparent electronics. The a-IGZO TFT was highly susceptible to ultraviolet (UV) light illumination, negative V th shift was observed under UV illumination. V th shift increased by the illumination time, and the V th shift values were −2.1 V, −1.4 V and 0.3 V at UV LED illumination time of 10 min, 5 min and 1 min, respectively. Persistent photo-induced current vanished when gate bias switched off.