Stability of amorphous InAlZnO thin-film transistors

The stability of thin-film transistors (TFTs) with amorphous InAlZnO (a-IAZO) thin films as the channel layers was investigated. The devices annealed at 300 °C had a large threshold voltage (Vth) shift under gate voltage sweep, while the devices annealed at 400 °C were quite stable. The S value of the transfer characteristic curve was effectively reduced after 400 °C annealing as compared to 300 °C annealing. X-ray photo-electron spectroscopy results also showed oxygen deficiencies decreased as the annealing temperature increased. The improvement of TFTs stability might attribute to the reduction of trap states related to oxygen deficiencies. The 400 °C annealed a-IAZO TFTs exhibited small positive shift of threshold voltages under bias stress conditions, suggesting the a-IAZO might be a promising candidate for application in TFTs.