Thermal Stability of Amorphous InGaZnO Thin-Film Transistors With Different Oxygen-Contained Active Layers

Effect of the oxygen flow rate for active-layer deposition on the thermal stability of amorphous InGaZnO thin film transistors (a-IGZO TFTs) was investigated. The transfer characteristics of a-IGZO TFTs were measured at temperatures ranging from 298 to 398 K and a simple analytical model was used to relate the threshold voltage (Vth) decrease with increasing temperature to the formation of the point defects in a-IGZO films. Lower oxygen flow rate for active-layer deposition was proved to improve the thermal stability of a-IGZO TFTs, as was confirmed to be due to the increase in defect formation energy with the oxygen flow rate decreasing by the related theoretical analysis and XPS measurements.