Impact of constant bias stress on reliability of IGZO thin-film transistors on softening polymer

Abstract

This study analyzed the electrical behavior of indium‑gallium‑zinc-oxide (IGZO) thin-film transistors (TFTs) under different applied voltages. The IGZO TFTs were fabricated on a polymer substrate using full photolithographic processes. The electrical performance was monitored under constant bias stress for 10,000 s and the analysis revealed relatively high field-effect mobility (>10 cm²/Vs) when higher voltages (>5 V) were applied to the IGZO TFTs. Furthermore, the experimental results demonstrated shifts in the threshold voltage (V_TH), mobility, and saturation drain current, exhibiting a strong dependence on the applied voltage. After 10,000 s of bias stress, the threshold voltage shift varied by 0.5 V for the lowest applied voltage and exceeded 5 V for the higher values. Moreover, the electrical analysis indicated a significant reduction in the lifetime of IGZO TFTs when the applied voltage exceeded 15 V. These findings enable a comparative analysis of the impact of bias stress on mobility, V_TH, and driving current, offering a pathway to optimize the electrical performance of TFTs-based flexible applications. Furthermore, by exploring the mechanism behind the changes induced by the constant electric field at the gate contact, this work provides insights for predicting the reliability and lifetime of novel devices tailored for wearable, flexible, and biomedical technologies.