Effect of aluminum and Indium composition on the bias-illumination-stress stability of solution-processed transparent Al-In-Zn-O thin-film transistors

The effect of aluminum and Indium composition on the negative bias-illumination-stress (NBIS) stability was investigated for the In-Zn-O (IZO) and Al-In-Zn-O (AIZO) thin-film transistors (TFTs). The fabricated TFTs with top-gate bottom-contact structure showed distinct variations in the threshold voltage shift (ΔV_th) under the NBIS at blue wavelength with changing the channel layer composition. The ΔV_th for the IZO TFT were suppressed by incorporating Al from 2.44 to 1.82 V under the NBIS conditions for 10⁴ s. The incorporation of Al composition was confirmed to enhance the NBIS stability at the cost of decrease in mobility. These composition dependent NBIS instabilities mainly originated from the photo-induced excitation from [V_o] to [V_o²⁺].