Comparative Studies of Long-Term Ambiance and Electrical Stress Stability of IGZO Thin-Film Transistors Annealed Under Hydrogen and Nitrogen Ambiance

The stability of hydrogenated indium-gallium-zincoxide (IGZO) thin-film transistors (TFTs) was investigated. Hydrogenation of the IGZO TFTs was carried out by high-pressure hydrogen annealing. The IGZO TFTs annealed under nitrogen (N
₂
) ambiance were also fabricated for the comparative studies. The devices were kept in the air ambiance, and their performance was periodically measured to investigate their longterm stability. The long-term stability of the hydrogenated TFTs was better than that of the N
₂
-annealed TFTs. Electrical bias stress was applied to both the types of the IGZO TFTs to study the electrical robustness of the devices. Under positive gate-bias stress, the optimized hydrogenated IGZO TFTs exhibited better reliability than those annealed in N
₂
ambiance in terms of threshold voltage (V
_th
) and saturation mobility (μ
_sat
).