Improvement in Photo-Bias Stability of High-Mobility Indium Zinc Oxide Thin-Film Transistors by Oxygen High-Pressure Annealing

This letter examines the effect of oxygen (O
₂
) high-pressure annealing (HPA) on indium zinc oxide (IZO) thin-film transistors (TFTs) with a high-quality Al
₂
O
₃
passivation layer. The IZO TFTs anneal under an O
₂
atmosphere at 9 atm exhibits a high field-effect mobility, low subthreshold gate swing, moderate threshold voltage (Vth), and high I
_ON/OFF
ratio of 30.4 cm
²
/Vs, 0.10 V/decade, 0.79 V, and 10
⁸
, respectively. In addition, the O
₂
HPA-treated IZO TFT has superior reliability (ΔVth= -0.5 V) to that of the 0.2-atm-annealed device (ΔVth=-3.7 V) under negative bias illumination stress conditions. This improvement can be attributed to the reduced concentration of oxygen vacancy defects in the IZO channel layer during the O
₂
HPA treatment.