Low-Cost SiO ₂ Gate Insulator for Amorphous IGZO Thin-Film Transistors with Enhanced Electrical Performance

We report the deposition of high-quality SiO 2 gate insulator by atmospheric spray pyrolysis at 400 °C using tetraethyl orthosilicate (TEOS) for high-performance amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) followed by UV−O 3 and Ar/O 2 plasma treatment with prolonged air annealing. The SiO 2 exhibits a dielectric constant of ∼4.0, low leakage current (∼10 −7 A/cm 2 at 1 MV/cm), and high breakdown field (9.1 MV/cm). The SiO 2 /a-IGZO TFTs exhibit hysteresis-free transfer characteristics with a field effect-mobility of 22.73 cm 2 /Vs, I ON / I OFF drain current ratio >10 7, subthreshold swing 88 mV/dec, and V TH of −0.65 V. The TFT exhibits excellent bias stress stability with low interface state density (∼5 × 10 11 /cm 2 eV).