Low Voltage Driven, Stable Solution-Processed Zinc-Tin-Oxide TFT with HfOy and AlOx Stack Gate Dielectric

We report on low voltage driven, solution processed zinc-tin oxide (ZTO) transistors with a spin-coated hafnium oxide (HfO y ) and aluminum oxide (AlO x ) stack gate insulator (HfO y /AlO x ). The ZTO TFT with a HfO y /AlO x dielectric processed at the maximum temperature of 400°C exhibits the field-effect mobility of 3.84 cm 2 /V s, subthreshold swing of 117 mV/dec., and threshold voltage (V th ) of 0.84 V. The positive gate bias stress degradation of V th with time follows a stretched exponential behavior with a time constant of 1.13 × 10 7 s, indicating stable TFT.