Enhancement in Performance and Reliability of Fully Trans-Parent A-IGZO Top Gate Thin-Film Transistors by a Two-Step Annealing TreatmentEnhancement in Performance and Reliability of Fully Trans-Parent A-IGZO Top Gate Thin-Film Transistors by a Two-Step Annealing Treatment

A two-step annealing treatment was applied on a fully transparent amorphous InGaZnO4 (a-IGZO) top gate thin-film transistor (TG-TFT) to improve the device perfor-mance. The electrical properties and stabilities of a-IGZO TG TFTs were significantly im-proved as the 1st-annealing temperature increased from 150°C to 350°C with a 300°C 2nd-annealing treatment. The a-IGZO TG-TFT with the 300°C 1st-annealing treatment demonstrated the overall best performance, which has a mobility of 13.05 cm2/(V·s), a threshold voltage (Vth) of 0.33 V, a subthreshold swing of 130 mV/dec, and a Ion/Ioff of 1.73×108. The Vth deviation (ΔVth) was -0.032 V and -0.044 V, respectively, after a 7200 s positive and negative bias stress under the gate bias voltage VG = ± 3 V and VD = 0.1 V. The PL spectra results revealed that the distribution and the density of defects in a-IGZO films were changed after the 1st-annealing treatment, whereas, XPS results displayed that the contents of oxygen vacancy and Ga-O bond varied in annealed a-IGZO films. In addition, a-IGZO TG-TFT had achieved a transmittance of over 90%. Researches on effects of the 1st-annealing treatment will contribute the fabrication of highly stable top-gate TFTs in the fields of transparent flexible electronics.