Performance and Stability of Thin Film Transistors Made of Amorphous Indium Zinc Tungsten Oxides

The thin film transistors (TFTs), with channel layer made of magnetron-sputtered amorphous indium zinc tungsten oxides (a-IZWO), were fabricated on substrate of n-type thermal oxidized Si. The influence of the annealing conditions and channel width/length ratio on the performance and stability of TFTs was investigated. The results show that the width/length ratio and annealing time has a major impact. To be specific, annealed at 200℃ for 120 min in air, the optimized properties of TFT with channel width/length ratio of 400 μm:400 μm included:a field effect mobility of 7. 29 cm²/Vs, a threshold voltage of -2. 86 V, a current on/off ratio over 10⁷, and a subthreshold swing of 0. 13 V/decade. As the annealing time and width/length ratio increased, the intrinsic oxygen vacancy density in the channel layer and adsorbed O^-2/H₂O⁺ ions on the backchannel surfaces considerably decreased, resulting in an increasing enhancement of the gate bias stability.