High Mobility Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistor by Aluminum Oxide Passivation Layer

This letter demonstrates a high-mobility amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) with aluminum oxide (Al ₂ O ₃ ) passivation layer by radio frequency (RF) magnetron sputtering and copper (Cu) source/drain electrodes. The fabricated a-IGZO TFT exhibited 20 times higher saturation mobility (142.0 cm ² /Vs) than the reference device without Al ₂ O ₃ passivation layer. The generation of metallic indium at the back-channel interface caused by the bombardment of the sputtered Al ₂ O ₃ is the main principle for the remarkable enhancement of saturation mobility. Furthermore, the a-IGZO TFT maintains high mobility and air-ambient-stable characteristics up to four months in ambient conditions.