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 degrees C had a large threshold voltage (V-th) shift under gate voltage sweep, while the devices annealed at 400 degrees C were quite stable. The S value of the transfer characteristic curve was effectively reduced after 400 degrees C annealing as compared to 300 degrees 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 degrees 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. (C) 2014 American Vacuum Society.