35‐4: High‐Mobility and High‐Negative Bias Illumination Stress Stability Based on ITZO/IGZO Bilayer Thin Film Transistors

In order to balance the stability and mobility of amorphous oxide semiconductor thin‐film transistors (AOS TFTs), we designate a stacked channel TFT structure incorporating an electron relaxation layer (CRL) and an electron transport layer (CTL). Rich In‐ITZO is chosen as the CTL, and a rich Ga‐IGZO material with a short photogenerated electron lifetime served as the CRL. Bilayer TFTs with CRL/CTL ratios of 5/20, 10/20, 15/20, 20/20, and 30/20 nm are prepared. The results reveal that the CRL/CTL stacked structure effectively enhances stability while maintaining high mobility. With an increase in CTL thickness, the TFT mobility also increases. Ultimately, three groups of devices with both high mobility and stability are fabricated: 10/20 TFT with a field‐effect mobility (μFE) of approximately 48.58 cm 2 V -1 s -1 and a negative bias illumination stress (NBIS) threshold voltage shift (|ΔV th |) of around ‐1.14 V; 15/20 TFT with µFE~54.08 cm 2 V -1 s -1 and NBIS |ΔV th |~ ‐2.35 V; and 20/20 TFT with µFE~65.98 cm 2 V -1 s -1 and NBIS |ΔV th |~ ‐2.07 V. This suggests that the CRL/CTL structure can achieve high‐performance TFTs suitable for various display applications.