Effect of Aluminum and Gallium Doping on the Performance of Solution-Processed Indium Oxide Thin-Film Transistors

Thin-film transistors (TFTs) with indium gallium oxide and aluminum indium oxide as a channel layer were fabricated via an aqueous route with low temperature annealing. The effects of chemical composition on electrical performance were examined. The fabricated IGO and AIO TFTs exhibited mobility in the range of 3.9-10.7 cm ²·V^-1·s^-1 with an on-to-off current ratio over 10⁶ and a sub-threshold swing of below 0.7 V/dec at the optimized composition. The optimized IGO and AIO thin-films were in an amorphous phase, which has an advantage in large area uniformity. Finally, we performed a positive and negative bias test on the optimized IGO and AIO TFTs to understand the resistance to external bias stress. The turn-on voltage shift of the optimized IGO and AIO TFTs, annealed at 300 ^°C, were 1.45 V (negative bias stress), and 1.56 V (positive bias stress) with 3600 s stress, respectively.