High performance low temperature solution-processed zinc oxide thin film transistor

Amorphous zinc oxide thin films have been processed out of an aqueous solution applying a one step synthesis procedure. For this, zinc oxide containing crystalline water (ZnO⋅ × H2O) is dissolved in aqueous ammonia (NH3), making use of the higher solubility of ZnO⋅ × H2O compared with the commonly used zinc oxide. Characteristically, as-produced layers have a thickness of below 10 nm. The films have been probed in standard thin film transistor devices, using silicon dioxide as dielectric layer. Keeping the maximum process temperature at 125 °C, a device mobility of 0.25 cm2V− 1s− 1 at an on/off ratio of 106 was demonstrated. At an annealing temperature of 300 °C, the performance could be optimized up to a mobility of 0.8 cm2V− 1s− 1.