Engineered Amorphous Indium Oxide Thin-Film Transistors for Electrical Performance Enhancement by Focused Oxygen Plasma Treatment

Amorphous In₂O₃ is an extensively studied semiconductor for transparent electronic applications because of its large area uniformity and high saturation mobility (μ_sat). Here, we have investigated the effect of focused oxygen plasma (FOP) treatment on solution-processed In₂O₃ thin films to determine the optimum treatment time and to assess the effect of the plasma on the chemical composition of the film. To analyze the effect of the FOP treatment time on the In₂O₃ thin-film transistors (TFTs), the thin films were exposed to energetic oxygen particles of the plasma for 3 min, 6 min, and 9 min. The performance of the In₂O₃ TFTs exposed to FOP for different times were compared to that of the TFT with a pristine oxide film. The results indicated that temporary exposure of the film surface to oxygen plasma improves the charge transport properties, thus optimizing the device performance. At 6 min of treatment, the μ_sat was improved from 1.35 cm²/Vs to 2.48 cm²/Vs, and the threshold voltage was reduced from 3.21 V to 0.51 V, while also improving the bias stress stability. However, the TFT performance degraded with longer treatment times. The device stability was also analyzed, which revealed that the 6-min treatment provides the optimal gate bias stability and long-term stability for the In₂O₃ active layers.