Light-induced bias stability of crystalline indium-tin-zinc-oxide thin film transistors

Crystalline Indium–Tin–Zinc-Oxide (c-ITZO) thin films transistors (TFTs) are investigated to confirm the device performance and analyze the device reliability of c-ITZO under positive/negative bias stress with/without illumination. The deposited ITZO thin film is controlled by adjusting the annealing temperature to obtain the crystal structure. We observe the transition from an amorphous to a crystalline structure at a temperature above 700 °C. As a result, the c-ITZO TFTs were confirmed to exhibit a high electron mobility when compared with amorphous ITZO (a-ITZO) TFTs. The considerable enhancement in device reliability for c-ITZO TFTs is particularly measured under negative bias stress and negative bias illumination stress without degradation in the electron mobility, and this is related to the decrease in defects after a phase change from amorphous to crystalline. These results suggest that the c-ITZO TFT can be applied in next-generation displays.