A room-temperature flexible amorphous indium-gallium-zinc oxide thin film transistor (a-IGZO TFT) technology is developed on plastic substrates, in which both the gate dielectric and passivation layers of the TFTs are formed by an anodic oxidation (anodization) technique. While the gate dielectric Al2O3 is grown with a conventional anodization on an Al:Nd gate electrode, the channel passivation layer Al2O3 is formed using a localized anodization technique. The anodized Al2O3 passivation layer shows a superior passivation effect to that of PECVD SiO2. The room-temperature-processed flexible a-IGZO TFT exhibits a field-effect mobility of 7.5 cm2/V·s, a subthreshold swing of 0.44 V/dec, an on-off ratio of 3.1 × 108, and an acceptable gate-bias stability with threshold voltage shifts of 2.65 and -1.09 V under positive gate-bias stress and negative gate-bias stress, respectively. Bending and fatigue tests confirm that the flexible a-IGZO TFT also has a good mechanical reliability, with electrical performances remaining consistent up to a strain of 0.76% as well as after 1200 cycles of fatigue testing.
Keywords: amorphous indium−gallium−zinc oxide (a-IGZO); anodization; flexible; room temperature; thin film transistor (TFT).