Enhancement of Electrical Stability in Solution Processed In2O3 TFT by an Oxygen Plasma-Assisted Treatment

Solution processing is a promising alternative to fabricate transparent metal oxide layers for display applications. One drawback is poor bias stability of the devices with as-deposited films. Here, we report on the postdeposition treatment of solution-processed indium oxide (In2O3) thin-film transistors (TFTs) performed by a helical-focused plasma source. The RF generator power of the plasma source is varied to optimize the treatment conditions. The electrical performance of the In2O3 TFTs showed improvement after treatment at lower and medium RF power, but when increased to 180 W, no transistor operation was observed. The best bias stability based on current deterioration and threshold voltage shift was observed when the RF power of the plasma generator was set to 60 W. The oxide films were further studied by measuring the optical absorbance, performing atomic force microscopy to analyze the surface roughness, and measuring the water contact angle to assess the hydrophilicity. A resistive load-type inverter was constructed by connecting optimized In2O3 TFTs with a resistor of 20 \text{M}\Omega and the inversion characteristics were assessed.