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.